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+The Project Gutenberg EBook of Handbook of Medical Entomology, by 
+William Albert Riley and Oskar Augustus Johanssen
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Handbook of Medical Entomology
+
+Author: William Albert Riley
+        Oskar Augustus Johanssen
+
+Release Date: November 11, 2010 [EBook #34279]
+
+Language: English
+
+Character set encoding: UTF-8
+
+*** START OF THIS PROJECT GUTENBERG EBOOK HANDBOOK OF MEDICAL ENTOMOLOGY ***
+
+
+
+
+Produced by Bryan Ness, Iris Schimandle, Brownfox and the
+Online Distributed Proofreading Team at http://www.pgdp.net
+(This file was produced from images generously made
+available by The Internet Archive/American Libraries.)
+
+
+
+
+
+Transcriber's Note: Barring some obvious typos, the text has been left
+as printed. Discrepancies identified are listed at the end of the text.
+
+
+
+
+[Illustration: Some early medical entomology. Athanasius Kircher's
+illustration of the Italian tarantula and the music prescribed as an
+antidote for the poison of its bite. (1643).]
+
+
+
+
+HANDBOOK OF MEDICAL
+
+ENTOMOLOGY
+
+WM. A. RILEY, PH.D.
+
+Professor of Insect Morphology and Parasitology, Cornell University
+
+and
+
+O. A. JOHANNSEN, PH.D.
+
+Professor of Biology, Cornell University
+
+[Illustration]
+
+ITHACA, NEW YORK
+
+THE COMSTOCK PUBLISHING COMPANY
+
+1915
+
+
+COPYRIGHT, 1915
+
+BY THE COMSTOCK PUBLISHING COMPANY,
+
+ITHACA, N. Y.
+
+
+Press of W. F. Humphrey
+Geneva, N. Y.
+
+
+
+
+PREFACE
+
+
+The Handbook of Medical Entomology is the outgrowth of a course of
+lectures along the lines of insect transmission and dissemination of
+diseases of man given by the senior author in the Department of
+Entomology of Cornell University during the past six years. More
+specifically it is an illustrated revision and elaboration of his "Notes
+on the Relation of Insects to Disease" published January, 1912.
+
+Its object is to afford a general survey of the field, and primarily to
+put the student of medicine and entomology in touch with the discoveries
+and theories which underlie some of the most important modern work in
+preventive medicine. At the same time the older phases of the
+subject--the consideration of poisonous and parasitic forms--have not
+been ignored.
+
+Considering the rapid shifts in viewpoint, and the development of the
+subject within recent years, the authors do not indulge in any hopes
+that the present text will exactly meet the needs of every one
+specializing in the field,--still less do they regard it as complete or
+final. The fact that the enormous literature of isolated articles is to
+be found principally in foreign periodicals and is therefore difficult
+of access to many American workers, has led the authors to hope that a
+summary of the important advances, in the form of a reference book may
+not prove unwelcome to physicians, sanitarians and working
+entomologists, and to teachers as a text supplementing lecture work in
+the subject.
+
+Lengthy as is the bibliography, it covers but a very small fraction of
+the important contributions to the subject. It will serve only to put
+those interested in touch with original sources and to open up the
+field. Of the more general works, special acknowledgment should be made
+to those of Banks, Brumpt, Castellani and Chalmers, Comstock, Hewitt,
+Howard, Manson, Mense, Neveau-Lemaire, Nuttall, and Stiles.
+
+To the many who have aided the authors in the years past, by suggestions
+and by sending specimens and other materials, sincerest thanks is
+tendered. This is especially due to their colleagues in the Department
+of Entomology of Cornell University, and to Professor Charles W. Howard,
+Dr. John Uri Lloyd, Mr. A. H. Ritchie, Dr. I. M. Unger, and Dr. Luzerne
+Coville.
+
+They wish to express indebtedness to the authors and publishers who have
+so willingly given permission to use certain illustrations. Especially
+is this acknowledgment due to Professor John Henry Comstock, Dr. L. O.
+Howard, Dr. Graham-Smith, and Professor G. H. T. Nuttall. Professor
+Comstock not only authorized the use of departmental negatives by the
+late Professor M. V. Slingerland (credited as M. V. S.), but generously
+put at their disposal the illustrations from the MANUAL FOR THE STUDY OF
+INSECTS and from the SPIDER BOOK. Figures 5 and 111 are from Peter's
+"Der Arzt und die Heilkunst in der deutschen Vergangenheit." It should
+be noted that on examining the original, it is found that Gottfried's
+figure relates to an event antedating the typical epidemic of dancing
+mania.
+
+                                                  WM. A. RILEY.
+                                                  O. A. JOHANNSEN.
+
+  CORNELL UNIVERSITY,
+  January, 1915.
+
+
+
+
+ADDITIONS AND CORRECTIONS
+
+vi line 11, for Heilkunft read Heilkunst.
+
+18 line 2, for tarsi read tarsus.
+
+32 line 21, and legend under fig. 23, for C. (Conorhinus) abdominalis
+      read Melanolestes abdominalis.
+
+47 legend under figure for 33c read 34.
+
+92 line 22 and 25, for sangiusugus read sanguisugus.
+
+116 legend under fig. 83, for Graham-Smith read Manson.
+
+136 line 10, from bottom, insert "ring" after "chitin".
+
+137 line 3, for meditatunda read meditabunda.
+
+145 line 7, from bottom, for Rs read R_5.
+
+158 line 20, for have read has.
+
+212 after the chapter heading insert "continued".
+
+219 line 10, from bottom, for Cornohinus read Conorhinus.
+
+266 line 1, fig. 158j refers to the female.
+
+272 line 5, insert "palpus" before "and leg".
+
+281 line 6, for discodial read discoidal.
+
+281 last line, insert "from" before "the".
+
+284 line 5, for "tubercle of" read "tubercle or".
+
+305 lines 19, 28, 44, page 306 lines 1, 9, 22, 27, 30, page 307 line 7,
+      page 309 lines 8, 11, for R_{4+5} read M_{1+2}.
+
+309 legend under fig. 168 add Bureau of Entomology.
+
+312 line 36, for "near apex" read "of M_{1+2}".
+
+313 running head, for Muscidæ read Muscoidea.
+
+314 line 29, for "distal section" read "distally M_{1+2}".
+
+315 legend under fig. 172, for Pseudopyrellia read Orthellia, for
+      Lyperosia read Hæmatobia, for Umbana read urbana.
+
+323 and 325 legends under the figures, add "After Dr. J. H. Stokes".
+
+328 line 7 from bottom for Apiochæta read Aphiochæta.
+
+
+
+
+CONTENTS
+
+
+CHAPTER I
+
+INTRODUCTION                                                  1-5
+
+  Early suggestions regarding the transmission of disease by
+    insects.
+  The ways in which arthropods may affect the health of man.
+
+
+CHAPTER II
+
+ARTHROPODS WHICH ARE DIRECTLY POISONOUS                       6-56
+
+  The Araneida, or Spiders.
+    The tarantulas. Bird spiders. Spiders of the genus
+      Latrodectus. Other venomous spiders. Summary.
+  The Pedipalpida, or whip-scorpions.
+  The Scorpionida, or true scorpions.
+  The Solpugida, or solpugids.
+  The Acarina, or mites and ticks.
+  The Myriapoda, or centipedes and millipedes.
+  The Hexapoda, or true insects.
+    Piercing or biting insects poisonous to man.
+      Hemiptera, or true bugs.
+        The Notonectidæ or back-swimmers. Belostomidæ or giant
+          water-bugs. Reduviidæ, or assassin bugs. Other
+          Hemiptera reported as poisonous to man.
+      Diptera; the midges, mosquitoes and flies.
+    Stinging insects.
+      Apis mellifica, the honey bee. Other stinging forms.
+    Nettling insects.
+      Lepidoptera, or butterflies and moths. Relief from
+        poisoning by nettling larvæ.
+    Vescicating insects and those possessing other poisons
+      in their blood plasma. The blister beetles. Other
+      cryptotoxic insects.
+
+
+CHAPTER III
+
+PARASITIC ARTHROPODS AFFECTING MAN                            57-130
+
+  Acarina, or mites.
+    The Trombidiidæ, or harvest mites.
+    The Ixodoidea, or ticks.
+      Argasidæ. Ixodidæ. Treatment of tick bites.
+    The mites.
+      Dermanyssidæ. Tarsonemidæ. Sarcoptidæ, the itch mites.
+        Demodecidæ, the follicle mites.
+  Hexapoda, or true insects.
+    Siphunculata, or sucking lice.
+    Hemiptera.
+    The bed-bug. Other bed-bugs.
+  Parasitic Diptera, or flies.
+    Psychodidæ, or moth flies. Phlebotominæ. Culicidæ, or
+      mosquitoes. Simuliidæ, or black-flies. Chironomidæ, or
+      midges. Tabanidæ, or horse-flies. Leptidæ or
+      snipe-flies. Oestridæ, or bot-flies. Muscidæ, the
+      stable-fly and others.
+  Siphonaptera, or fleas.
+    The fleas affecting man, the dog, cat, and rat.
+    The true chiggers, or chigoes.
+
+CHAPTER IV
+
+ACCIDENTAL OR FACULTATIVE PARASITES                           131-143
+
+  Acarina, or mites.
+  Myriapoda, or centipedes and millipedes.
+  Lepidopterous larvæ.
+  Coleoptera, or beetles.
+  Dipterous larvæ causing myiasis.
+    Piophila casei, the cheese skipper. Chrysomyia macellaria,
+      the screw-worm fly. Calliphorinæ, the bluebottles.
+      Muscinæ, the house or typhoid fly, and others.
+      Anthomyiidæ, the lesser house-fly and others.
+      Sarcophagidæ, the flesh-flies.
+
+
+CHAPTER V
+
+ARTHROPODS AS SIMPLE CARRIERS OF DISEASE                      144-163
+
+  The house or typhoid fly as a carrier of disease.
+  Stomoxys calcitrans, the stable-fly.
+  Other arthropods which may serve as simple carriers of
+    pathogenic organisms.
+
+
+CHAPTER VI
+
+ARTHROPODS AS DIRECT INOCULATORS OF DISEASE GERMS             164-174
+
+  Some illustrations of direct inoculations of disease germs
+    by arthropods.
+  The rôle of fleas in the transmission of the plague.
+
+
+CHAPTER VII
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC ORGANISMS         175-185
+
+  Insects as intermediate hosts of tape-worms.
+  Arthropods as intermediate hosts of nematode worms.
+    Filariasis and mosquitoes.
+  Other nematode parasites of man and animals.
+
+
+CHAPTER VIII
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA          186-211
+
+  Mosquitoes and malaria.
+  Mosquitoes and yellow fever.
+
+
+CHAPTER IX
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA          212-229
+
+  Insects and trypanosomiases.
+    Fleas and lice as carriers of Trypanosoma lewisi.
+    Tsetse-flies and nagana.
+    Tsetse-flies and sleeping sickness in man.
+    South American trypanosomiasis.
+    Leishmanioses and insects.
+  Ticks and diseases of man and animals.
+    Cattle tick and Texas fever.
+    Ticks and Rocky Mountain Spotted fever of man.
+
+
+CHAPTER X
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA
+(CONTINUED)                                                   230-240
+
+  Arthropods and Spirochætoses of man and animals.
+    African relapsing fever of man.
+    European relapsing fever.
+    North African relapsing fever of man.
+    Other types of relapsing fever of man.
+    Spirochætosis of fowls.
+    Other spirochæte diseases of animals.
+  Typhus fever and lice.
+
+
+CHAPTER XI
+
+SOME POSSIBLE, BUT IMPERFECTLY KNOWN CASES OF
+ARTHROPOD TRANSMISSION OF DISEASE                             241-256
+
+  Infantile paralysis, or acute anterior poliomyelitis.
+  Pellagra. Leprosy. Verruga peruviana. Cancer.
+
+
+CHAPTER XII
+
+KEYS TO THE ARTHROPODS NOXIOUS TO MAN                         257-317
+
+  Crustacea.
+  Myriapoda, or centipedes and millipedes.
+  Arachnida (Orders of).
+    Acarina or ticks.
+  Hexapoda (Insecta).
+    Siphunculata and Hemiptera (lice and true bugs).
+    Diptera (mosquitoes, midges, and flies).
+    Siphonaptera (fleas).
+
+
+APPENDIX
+
+Hydrocyanic acid gas against household insects                318-320
+  Proportion of ingredients. A single room as an example.
+    Fumigating a large house. Precautions.
+
+Lesions produced by the bite of the black-fly                 321-326
+
+
+BIBLIOGRAPHY                                                  327-340
+
+
+INDEX                                                         341-348
+
+
+
+
+CHAPTER I.
+
+INTRODUCTION
+
+EARLY SUGGESTIONS REGARDING THE TRANSMISSION OF DISEASE BY INSECTS
+
+
+Until very recent years insects and their allies have been considered as
+of economic importance merely in so far as they are an annoyance or
+direct menace to man, or his flocks and herds, or are injurious to his
+crops. It is only within the past fifteen years that there has sprung
+into prominence the knowledge that in another and much more insiduous
+manner, they may be the enemy of mankind, that they may be among the
+most important of the disseminators of disease. In this brief period,
+such knowledge has completely revolutionized our methods of control of
+certain diseases, and has become an important weapon in the fight for
+the conservation of health.
+
+It is nowhere truer than in the case under consideration that however
+abrupt may be their coming into prominence, great movements and great
+discoveries do not arise suddenly. Centuries ago there was suggested the
+possibility that insects were concerned with the spread of disease, and
+from time to time there have appeared keen suggestions and logical
+hypotheses along this line, that lead us to marvel that the
+establishment of the truths should have been so long delayed.
+
+One of the earliest of these references is by the Italian physician,
+Mercurialis, who lived from 1530 to 1607, during a period when Europe
+was being ravaged by the dread "black death", or plague. Concerning its
+transmission he wrote: "There can be no doubt that flies feed on the
+internal secretions of the diseased and dying, then, flying away, they
+deposit their excretions on the food in neighboring dwellings, and
+persons who eat of it are thus infected."
+
+It would be difficult to formulate more clearly this aspect of the facts
+as we know them to-day, though it must always be borne in mind that we
+are prone to interpret such statements in the light of present-day
+knowledge. Mercurialis had no conception of the animate nature of
+contagion, and his statement was little more than a lucky guess.
+
+Much more worthy of consideration is the approval which was given to his
+view by the German Jesuit, Athanasius Kircher in 1658. One cannot read
+carefully his works without believing that long before Leeuwenhook's
+discovery, Kircher had seen the larger species of bacteria. Moreover, he
+attributed the production of disease to these organisms and formulated,
+vaguely, to be sure, a theory of the animate nature of contagion. It has
+taken two and a half centuries to accumulate the facts to prove his
+hypothesis.
+
+The theory of Mercurialis was not wholly lost sight of, for in the
+medical literature of the eighteenth century there are scattered
+references to flies as carriers of disease. Such a view seems even to
+have been more or less popularly accepted, in some cases. Gudger (1910),
+has pointed out that, as far back as 1769, Edward Bancroft, in "An Essay
+on the Natural History of Guiana in South America," wrote concerning the
+contagious skin-disease known as "Yaws": "It is usually believed that
+this disorder is communicated by the flies who have been feasting on a
+diseased object, to those persons who have sores, or scratches, which
+are uncovered; and from many observations, I think this is not
+improbable, as none ever receive this disorder whose skins are whole."
+
+Approaching more closely the present epoch, we find that in 1848, Dr.
+Josiah Nott, of Mobile, Alabama, published a remarkable article on the
+cause of yellow fever, in which he presented "reasons for supposing its
+specific cause to exist in some form of insect life." As a matter of
+fact, the bearing of Nott's work on present day ideas of the insect
+transmission of disease has been very curiously overrated. The common
+interpretation of his theory has been deduced from a few isolated
+sentences, but his argument appears quite differently when the entire
+article is studied. It must be remembered that he wrote at a period
+before the epoch-making discoveries of Pasteur and before the
+recognition of micro-organisms as factors in the cause of disease. His
+article is a masterly refutation of the theory of "malarial" origin of
+"all the fevers of hot climates," but he uses the term "insect" as
+applicable to the lower forms of life, and specific references to
+"mosquitoes," "aphids," "cotton-worms," and others, are merely in the
+way of similes.
+
+But, while Nott's ideas regarding the relation of insects to yellow
+fever were vague and indefinite, it was almost contemporaneously that
+the French physician, Louis Daniel Beauperthuy argued in the most
+explicit possible manner, that yellow fever and various others are
+transmitted by mosquitoes. In the light of the data which were available
+when he wrote, in 1853, it is not surprising that he erred by thinking
+that the source of the virus was decomposing matter which the mosquito
+took up and accidentally inoculated into man. Beauperthuy not only
+discussed the rôle of mosquitoes in the transmission of disease, but he
+taught, less clearly, that house-flies scatter pathogenic organisms. It
+seems that Boyce (1909) who quotes extensively from this pioneer work,
+does not go too far when he says "It is Dr. Beauperthuy whom we must
+regard as the father of the doctrine of insect-borne disease."
+
+In this connection, mention must be made of the scholarly article by the
+American physician, A. F. A. King who, in 1883, brought together an all
+but conclusive mass of argument in support of his belief that malaria
+was caused by mosquitoes. At about the same time, Finley, of Havana, was
+forcefully presenting his view that the mosquito played the chief rôle
+in the spread of yellow fever.
+
+To enter more fully into the general historical discussion is beyond the
+scope of this book. We shall have occasion to make more explicit
+references in considering various insect-borne diseases. Enough has been
+said here to emphasize that the recognition of insects as factors in the
+spread of disease was long presaged, and that there were not wanting
+keen thinkers who, with a background of present-day conceptions of the
+nature of disease, might have been in the front rank of investigators
+along these lines.
+
+
+THE WAYS IN WHICH ARTHROPODS MAY AFFECT THE HEALTH OF MAN
+
+When we consider the ways in which insects and their allies may affect
+the health of man, we find that we may treat them under three main
+groups:
+
+A. They may be directly poisonous. Such, for example, are the scorpions,
+certain spiders and mites, some of the predaceous bugs, and stinging
+insects. Even such forms as the mosquito deserve some consideration from
+this viewpoint.
+
+B. They may be parasitic, living more or less permanently on or in the
+body and deriving their sustenance from it.
+
+Of the parasitic arthropods we may distinguish, first, the _true
+parasites_, those which have adopted and become confirmed in the
+parasitic habit. Such are the itch mites, the lice, fleas, and the
+majority of the forms to be considered as parasitic.
+
+In addition to these, we may distinguish a group of _accidental_, or
+_facultative parasites_, species which are normally free-living, feeding
+on decaying substances, but which when accidentally introduced into the
+alimentary canal or other cavities of man, may exist there for a greater
+or less period. For example, certain fly larvæ, or maggots, normally
+feeding in putrifying meat, have been known to occur as accidental or
+facultative parasites in the stomach of man.
+
+C. Finally, and most important, arthropods may be transmitters and
+disseminators of disease. In this capacity they may function in one of
+three ways; as _simple carriers_, as _direct inoculators_, or as
+_essential hosts_ of disease germs.
+
+As simple carriers, they may, in a wholly incidental manner, transport
+from the diseased to the healthy, or from filth to food, pathogenic
+germs which cling to their bodies or appendages. Such, for instance, is
+the relation of the house-fly to the dissemination of typhoid.
+
+As direct inoculators, biting or piercing species may take up from a
+diseased man or animal, germs which, clinging to the mouth parts, are
+inoculated directly into the blood of the insect's next victim. It it
+thus that horse-flies may occasionally transmit anthrax. Similarly,
+species of spiders and other forms which are ordinarily perfectly
+harmless, may accidentally convey and inoculate pyogenic bacteria.
+
+It is as essential hosts of disease germs that arthropods play their
+most important rôle. In such cases an essential part of the life cycle
+of the pathogenic organism is undergone in the insect. In other words,
+without the arthropod host the disease-producing organism cannot
+complete its development. As illustrations may be cited the relation of
+the Anopheles mosquito to the malarial parasite, and the relation of the
+cattle tick to Texas fever.
+
+A little consideration will show that this is the most important of the
+group. Typhoid fever is carried by water or by contaminated milk, and in
+various other ways, as well as by the house-fly. Kill all the
+house-flies and typhoid would still exist. On the other hand, malaria is
+carried only by the mosquito, because an essential part of the
+development of the malarial parasite is undergone in this insect.
+Exterminate all of the mosquitoes of certain species and the
+dissemination of human malaria is absolutely prevented.
+
+Once an arthropod becomes an essential host for a given parasite it may
+disseminate infection in three different ways:
+
+1. By infecting man or animals who ingest it. It is thus, for example,
+that man, dog, or cat, becomes infected with the double-pored dog
+tapeworm, _Dipylidium caninum_. The cysticercoid stage occurs in the
+dog louse, or in the dog or cat fleas, and by accidentally ingesting the
+infested insect the vertebrate becomes infested. Similarly, _Hymenolepis
+diminuta_, a common tapeworm of rats and mice, and occasional in man,
+undergoes part of its life cycle in various meal-infesting insects, and
+is accidentally taken up by its definitive host. It is very probable
+that man becomes infested with _Dracunculus (Filaria) medinensis_
+through swallowing in drinking water, the crustacean, _Cyclops_,
+containing the larvæ of this worm.
+
+2. By infecting man or animals on whose skin or mucous membranes the
+insect host may be crushed or may deposit its excrement. The pathogenic
+organism may then actively penetrate, or may be inoculated by
+scratching. The causative organism of typhus fever is thus transmitted
+by the body louse.
+
+3. By direct inoculation by its bite, the insect host may transfer the
+parasite which has undergone development within it. The malarial
+parasite is thus transferred by mosquitoes; the Texas fever parasite by
+cattle ticks.
+
+
+
+
+CHAPTER II.
+
+ARTHROPODS WHICH ARE DIRECTLY POISONOUS
+
+
+Of all the myriads of insects and related forms, a very few are of
+direct use to man, some few others have forced his approbation on
+account of their wonderful beauty, but the great hordes of them are
+loathed or regarded as directly dangerous. As a matter of fact, only a
+very small number are in the slightest degree poisonous to man or to the
+higher animals. The result is that entomologists and lovers of nature,
+intent upon dissipating the foolish dread of insects, are sometimes
+inclined to go to the extreme of discrediting all statements of serious
+injury from the bites or stings of any species.
+
+Nevertheless, it must not be overlooked that poisonous forms do exist,
+and they must receive attention in a consideration of the ways in which
+arthropods may affect the health of man. Moreover, it must be recognized
+that "what is one man's meat, is another man's poison," and that in
+considering the possibilities of injury we must not ignore individual
+idiosyncrasies. Just as certain individuals may be poisoned by what, for
+others, are common articles of food, so some persons may be abnormally
+susceptible to insect poison. Thus, the poison of a bee sting may be of
+varying severity, but there are individuals who are made seriously sick
+by a single sting, regardless of the point of entry. Some individuals
+scarcely notice a mosquito bite, others find it very painful, and so
+illustrations of this difference in individuals might be multiplied.
+
+In considering the poisonous arthropods, we shall take them up by
+groups. The reader who is unacquainted with the systematic relationship
+of insects and their allies is referred to Chapter XII. No attempt will
+be made to make the lists under the various headings exhaustive, but
+typical forms will be discussed.
+
+
+ARANEIDA OR SPIDERS
+
+Of all the arthropods there are none which are more universally feared
+than are the spiders. It is commonly supposed that the majority, if not
+all the species are poisonous and that they are aggressive enemies of
+man and the higher animals, as well as of lower forms.
+
+That they really secrete a poison may be readily inferred from the
+effect of their bite upon insects and other small forms. Moreover, the
+presence of definite and well-developed poison glands can easily be
+shown. They occur as a pair of pouches (fig. 1) lying within the
+cephalothorax and connected by a delicate duct with a pore on the claw
+of the chelicera, or so-called "mandible" on the convex surface of the
+claw in such a position that it is not plugged and closed by the flesh
+of the victim.
+
+[Illustration: 1. Head of a spider showing poison gland (_c_) and its
+relation to the chelicera (_a_).]
+
+The glands may be demonstrated by slowly and carefully twisting off a
+chelicera and pushing aside the stumps of muscles at its base. By
+exercising care, the chitinous wall of the chelicera and its claw may be
+broken away and the duct traced from the gland to its outlet. The inner
+lining of the sac is constituted by a highly developed glandular
+epithelium, supported by a basement membrane of connective tissue and
+covered by a muscular layer, (fig. 2). The muscles, which are striated,
+are spirally arranged (fig. 1), and are doubtless under control of the
+spider, so that the amount of poison to be injected into a wound may be
+varied.
+
+[Illustration: 2. Section through a venom gland of Latrodectus
+13-guttatus showing the peritoneal, muscular and epithelial layers.
+After Bordas.]
+
+The poison itself, according to Kobert (1901), is a clear, colorless
+fluid, of oily consistency, acid reaction, and very bitter taste. After
+the spider has bitten two or three times, its supply is exhausted and
+therefore, as in the case of snakes, the poison of the bite decreases
+quickly with use, until it is null. To what extent the content of the
+poison sacs may contain blood serum or, at least, active principles of
+serum, in addition to a specific poison formed by the poison glands
+themselves, Kobert regards as an open question. He believes that the
+acid part of the poison, if really present, is formed by the glands and
+that, in the case of some spiders, the ferment-like, or better, active
+toxine, comes from the blood.
+
+[Illustration: 3. Chelicera of a spider.]
+
+But there is a wide difference between a poison which may kill an insect
+and one which is harmful to men. Certain it is that there is no lack of
+popular belief and newspaper records of fatal cases, but the evidence
+regarding the possibility of fatal or even very serious results for man
+is most contradictory. For some years, we have attempted to trace the
+more circumstantial newspaper accounts, which have come to our notice,
+of injury by North American species. The results have served, mainly, to
+emphasize the straits to which reporters are sometimes driven when there
+is a dearth of news. The accounts are usually vague and lacking in any
+definite clue for locating the supposed victim. In the comparatively few
+cases where the patient, or his physician, could be located, there was
+either no claim that the injury was due to spider venom, or there was no
+evidence to support the belief. Rarely, there was evidence that a
+secondary blood poisoning, such as might be brought about by the prick
+of a pin, or by any mechanical injury, had followed the bite of a
+spider. Such instances have no bearing on the question of the venomous
+nature of these forms.
+
+[Illustration: 4. The Italian tarantula (Lycosa tarantula). After
+Kobert.]
+
+The extreme to which unreasonable fear of the bites of spiders
+influenced the popular mind was evidenced by the accepted explanation of
+the remarkable dancing mania, or tarantism, of Italy during the Middle
+Ages. This was a nervous disorder, supposed to be due to the bite of a
+spider, the European tarantula (fig. 4), though it was also, at times,
+attributed to the bite of the scorpion. In its typical form, it was
+characterized by so great a sensibility to music that under its
+influence the victims indulged in the wildest and most frenzied dancing,
+until they sank to the ground utterly exhausted and almost lifeless. The
+profuse perspiring resulting from these exertions was supposed to be the
+only efficacious remedy for the disease. Certain forms of music were
+regarded as of especial value in treating this tarantism, and hence the
+name of "tarantella" was applied to them. Our frontispiece, taken from
+Athanasius Kircher's _Magnes sive de Arte Magnetica_, 1643 ed.,
+represents the most commonly implicated spider and illustrates some of
+what Fabre has aptly designated as "medical choreography."
+
+The disease was, in reality, a form of hysteria, spreading by sympathy
+until whole communities were involved, and was paralleled by the
+outbreaks of the so-called St. Vitus's or St. John's dance, which swept
+Germany at about the same time (fig. 5). The evidence that the spider
+was the cause of the first is about as conclusive as is that of the
+demoniacal origin of the latter. The true explanation of the outbreaks
+is doubtless to be found in the depleted physical and mental condition
+of the people, resulting from the wars and the frightful plagues which
+devastated all Europe previous to, and during these times. An
+interesting discussion of these aspects of the question is to be found
+in Hecker.
+
+[Illustration: 5. Dancing mania. Illustration from Johann Ludwig
+Gottfried's Chronik. 1632.]
+
+So gross has been the exaggeration and so baseless the popular fear
+regarding spiders that entomologists have been inclined to discredit all
+accounts of serious injury from their bites. Not only have the most
+circumstantial of newspaper accounts proved to be without foundation but
+there are on record a number of cases where the bite of many of the
+commoner species have been intentionally provoked and where the effect
+has been insignificant. Some years ago the senior author personally
+experimented with a number of the largest of our northern species, and
+with unexpected results. The first surprise was that the spiders were
+very unwilling to bite and that it required a considerable effort to get
+them to attempt to do so. In the second place, most of those
+experimented with were unable to pierce the skin of the palm or the back
+of the hand, but had to be applied to the thin skin between the fingers
+before they were able to draw blood. Unfortunately, no special attempt
+was made to determine, at the time, the species experimented with, but
+among them were _Theridion tepidariorum_, _Miranda aurantia_
+(_Argiopa_), _Metargiope trifasciata_, _Marxia stellata_, _Aranea
+trifolium_, _Misumena vatia_, and _Agelena nævia_. In no case was the
+bite more severe than a pin prick and though in some cases the sensation
+seemed to last longer, it was probably due to the fact that the mind was
+intent upon the experiment.
+
+[Illustration: 6. An American tarantula (Eurypelma hentzii). Natural
+size. After Comstock.]
+
+Similar experiments were carried out by Blackwell (1855), who believed
+that in the case of insects bitten, death did not result any more
+promptly than it would have from a purely mechanical injury of equal
+extent. He was inclined to regard all accounts of serious injury to man
+as baseless. The question cannot be so summarily dismissed, and we shall
+now consider some of the groups which have been more explicitly
+implicated.
+
+
+THE TARANTULAS.--In popular usage, the term "tarantula" is loosely
+applied to any one of a number of large spiders. The famous tarantulas
+of southern Europe, whose bites were supposed to cause the dancing
+mania, were Lycosidæ, or wolf-spiders. Though various species of this
+group were doubtless so designated, the one which seems to have been
+most implicated was _Lycosa tarantula_ (L.), (fig. 4). On the other
+hand, in this country, though there are many Lycosidæ, the term
+"tarantula" has been applied to members of the superfamily Avicularoidea
+(fig. 6), including the bird-spiders.
+
+Of the Old World Lycosidæ there is no doubt that several species were
+implicated as the supposed cause of the tarantism. In fact, as we have
+already noted, the blame was sometimes attached to a scorpion. However,
+there seems to be no doubt that most of the accounts refer to the spider
+known as _Lycosa tarantula_.
+
+There is no need to enter into further details here regarding the
+supposed virulence of these forms, popular and the older medical
+literature abound in circumstantial accounts of the terrible effects of
+the bite. Fortunately, there is direct experimental evidence which bears
+on the question.
+
+Fabre induced a common south European wolf-spider, _Lycosa narbonensis_,
+to bite the leg of a young sparrow, ready to leave the nest. The leg
+seemed paralyzed as a result of the bite, and though the bird seemed
+lively and clamored for food the next day, on the third day it died. A
+mole, bitten on the nose, succumbed after thirty-six hours. From these
+experiments Fabre seemed justified in his conclusion that the bite of
+this spider is not an accident which man can afford to treat lightly.
+Unfortunately, there is nothing in the experiments, or in the symptoms
+detailed, to exclude the probability that the death of the animals was
+the result of secondary infection.
+
+As far back as 1693, as we learn from the valuable account of Kobert,
+(1901), the Italian physician, Sanguinetti allowed himself to be bitten
+on the arm by two tarantulas, in the presence of witnesses. The
+sensation was equivalent to that from an ant or a mosquito bite and
+there were no other phenomena the first day. On the second day the wound
+was inflamed and there was slight ulceration. It is clear that these
+later symptoms were due to a secondary infection. These experiments have
+been repeated by various observers, among whom may be mentioned Leon
+Dufour, Josef Erker and Heinzel, and with the similar conclusion that
+the bite of the Italian tarantula ordinarily causes no severe symptoms.
+In this conclusion, Kobert, though firmly convinced of the poisonous
+nature of some spiders, coincides. He also believes that striking
+symptoms may be simulated or artificially induced by patients in order
+to attract interest, or because they have been assured that the bite,
+under all circumstances, caused tarantism.
+
+The so-called Russian tarantula, _Trochosa singoriensis_ (fig. 7), is
+much larger than the Italian species, and is much feared. Kobert carried
+out a series of careful experiments with this species and his results
+have such an important bearing on the question of the venomous nature of
+the tarantula that we quote his summary. Experimenting first on nearly a
+hundred living specimens of _Trochosa singoriensis_ from Crimea he says
+that:
+
+"The tarantulas, no matter how often they were placed on the skin,
+handled, and irritated, could not be induced to bite either myself, the
+janitor, or the ordinary experimental animals. The objection that the
+tarantulas were weak and indifferent cannot stand, for as soon as I
+placed two of them on the shaved skin of a rabbit, instead of an attack
+on the animal, there began a furious battle between the two spiders,
+which did not cease until one of the two was killed."
+
+[Illustration: 7. Trochosa singoriensis. After Kobert.]
+
+"Since the spiders would not bite, I carefully ground up the fresh
+animals in physiological salt solution, preparing an extract which must
+have contained, in solution, all of the poisonous substance of their
+bodies. While in the case of _Latrodectus_, as we shall see, less than
+one specimen sufficed to yield an active extract, I have injected the
+filtered extract of six fresh Russian tarantulas, of which each one was
+much heavier than an average _Latrodectus_, subcutaneously and into the
+jugular vein of various cats without the animals dying or showing any
+special symptoms. On the basis of my experiments I can therefore only
+say that the quantity of the poison soluble in physiological salt
+solution, even when the spiders are perfectly fresh and well nourished,
+is very insignificant. That the poison of the Russian tarantula is not
+soluble in physiological salt solution, is exceedingly improbable.
+Moreover, I have prepared alcoholic extracts and was unable to find them
+active. Since the Russian spider exceeds the Italian in size and in
+intensity of the bite, it seems very improbable to me that the
+pharmacological test of the Italian tarantula would yield essentially
+other results than those from the Russian species."
+
+To the AVICULAROIDEA belong the largest and most formidable appearing of
+the spiders and it is not strange that in the New World they have fallen
+heir to the bad reputation, as well as to the name of the tarantula of
+Europe. In this country they occur only in the South or in the far West,
+but occasionally living specimens are brought to our northern ports in
+shipments of bananas and other tropical produce, and are the source of
+much alarm. It should be mentioned, however, that the large spider most
+frequently found under such circumstances is not a tarantula at all, but
+one of the Heteropodidæ, or giant crab-spiders, (fig. 8).
+
+[Illustration: 8. The giant crab-spider or banana spider (Heteropoda
+venatoria). Natural size. After Comstock.]
+
+In spite of their prominence and the fear which they arouse there are
+few accurate data regarding these American tarantulas. It has often been
+shown experimentally that they can kill small birds and mammals, though
+it is doubtful if these form the normal prey of any of the species, as
+has been claimed. There is no question but that the mere mechanical
+injury which they may inflict, and the consequent chances of secondary
+infection, justify, in part, their bad reputation. In addition to the
+injury from their bite, it is claimed that the body hairs of several of
+the South American species are readily detached and are urticating.
+
+Recently, Phisalix (1912) has made a study of the physiological effects
+of the venom of two Avicularoidea, _Phormictopus carcerides_ Pocock,
+from Haiti and _Cteniza sauvagei_ Rossi, from Corsica. The glands were
+removed aseptically and ground up with fine, sterilized sand in
+distilled water. The resultant liquid was somewhat viscid, colorless,
+and feebly alkaline. Injected into sparrows and mice the extract of
+_Phormictopus_ proved very actively poisonous, that from a single spider
+being sufficient to kill ten sparrows or twenty mice. It manifested
+itself first and, above all, as a narcotic, slightly lowering the
+temperature and paralyzing the respiration. Muscular and cardiac
+weakening, loss of general sensibility, and the disappearance of
+reflexes did not occur until near the end. The extract from _Cteniza_
+was less active and, curiously enough, the comparative effect on
+sparrows and on mice was just reversed.
+
+
+SPIDERS OF THE GENUS LATRODECTUS.--While most of the popular accounts of
+evil effects from the bites of spiders will not stand investigation, it
+is a significant fact that, the world over, the best authenticated
+records refer to a group of small and comparatively insignificant
+spiders belonging to the genus _Latrodectus_, of the family Theridiidæ.
+The dread "Malmigniatte" of Corsica and South Europe, the "Karakurte" of
+southeastern Russia, the "Katipo" of New Zealand, the "Mena-vodi" and
+"Vancoho" of Madagascar, and our own _Latrodectus mactans_, all belong
+to this genus, and concerning all of these the most circumstantial
+accounts of their venomous nature are given. These accounts are not mere
+fantastic stories by uneducated natives but in many cases are reports
+from thoroughly trained medical men.
+
+The symptoms produced are general, rather than local. As summarized by
+Kobert (1901) from a study of twenty-two cases treated in 1888, in the
+Kherson (Russia) Government Hospital and Berislaw (Kherson) District
+Hospital the typical case, aside from complications, exhibits the
+following symptoms. The victim suddenly feels the bite, like the sting
+of a bee. Swelling of the barely reddened spot seldom follows. The
+shooting pains, which quickly set in, are not manifested at the point of
+injury but localized at the joints of the lower limb and in the region
+of the hip. The severity of the pain forces the victim to the hospital,
+in spite of the fact that they otherwise have a great abhorrence of it.
+The patient is unable to reach the hospital afoot, or, at least, not
+without help, for there is usually inability to walk. The patient, even
+if he has ridden, reaches the hospital covered with cold sweat and
+continues to perspire for a considerable period. His expression
+indicates great suffering. The respiration may be somewhat dyspnœic,
+and a feeling of oppression in the region of the heart is common. There
+is great aversion to solid food, but increasing thirst for milk and tea.
+Retention of urine, and constipation occur. Cathartics and, at night,
+strong narcotics are desired. Warm baths give great relief. After three
+days, there is marked improvement and usually the patient is dismissed
+after the fifth. This summary of symptoms agrees well with other
+trustworthy records.
+
+It would seem, then, that Riley and Howard (1889), who discussed a
+number of accounts in the entomological literature, were fully justified
+in their statement that "It must be admitted that certain spiders of the
+genus _Latrodectus_ have the power to inflict poisonous bites, which may
+(probably exceptionally and depending upon exceptional conditions) bring
+about the death of a human being."
+
+And yet, until recently the evidence bearing on the question has been
+most conflicting. The eminent arachnologist, Lucas, (1843) states that
+he himself, had been repeatedly bitten by the Malmigniatte without any
+bad effects. Dr. Marx, in 1890, gave before the Entomological Society of
+Washington, an account of a series of experiments to determine whether
+the bite of _Latrodectus mactans_ is poisonous or not. He described the
+poison glands as remarkably small[A] and stated that he had introduced
+the poison in various ways into guinea-pigs and rabbits without
+obtaining any satisfactory results. Obviously, carefully conducted
+experiments with the supposed venom were needed and fortunately they
+have been carried out in the greatest detail by Kobert (1901).
+
+This investigator pointed out that there were two factors which might
+account for the discrepancies in the earlier experiments. In the first
+place, the poison of spiders, as of snakes, might be so exhausted after
+two or three bites that further bites, following directly, might be
+without visible effect. Secondly, the application of the poison by means
+of the bite, is exceedingly inexact, since even after the most careful
+selection of the point of application, the poison might in one instance
+enter a little vein or lymph vessel, and in another case fail to do so.
+Besides, there would always remain an incalculable and very large amount
+externally, in the nonabsorptive epithelium. While all of these factors
+enter into the question of the effect of the bite in specific instances,
+they must be as nearly as possible obviated in considering the question
+of whether the spiders really secrete a venom harmful to man.
+
+Kobert therefore sought to prepare extracts which would contain the
+active principles of the poison and which could be injected in definite
+quantities directly into the blood of the experimental animal. For this
+purpose various parts of the spiders were rubbed up in a mortar with
+distilled water, or physiological salt solution, allowed to stand for an
+hour, filtered, and then carefully washed, by adding water drop by drop
+for twenty-four hours. The filtrate and the wash-water were then united,
+well mixed and, if necessary, cleared by centrifuging or by exposure to
+cold. The mixture was again filtered, measured, and used, in part, for
+injection and, in part, for the determination of the organic materials.
+
+Such an extract was prepared from the cephalothoraces of eight dried
+specimens of the Russian _Latrodectus_ and three cubic centimeters of
+this, containing 4.29 mg. of organic material, were injected into the
+jugular vein of a cat weighing 2450 grams. The previously very active
+animal was paralyzed and lay in whatever position it was placed. The
+sensibility of the skin of the extremities and the rump was so reduced
+that there was no reaction from cutting or sticking. There quickly
+followed dyspnœa, convulsions, paralysis of the respiratory muscles
+and of the heart. In twenty-eight minutes the cat was dead, after having
+exhibited exactly the symptoms observed in severe cases of poisoning of
+man from the bite of this spider.
+
+These experiments were continued on cats, dogs, guinea pigs and various
+other animals. Not only extracts from the cephalothorax, but from other
+parts of the body, from newly hatched spiders, and from the eggs were
+used and all showed a similar virulence. Every effort was made to avoid
+sources of error and the experiments, conducted by such a recognized
+authority in the field of toxicology, must be accepted as conclusively
+showing that this spider and, presumably, other species of the genus
+_Latrodectus_ against which the clinical evidence is quite parallel,
+possess a poison which paralyzes the heart and central nervous system,
+with or without preliminary stimulus of the motor center. If the
+quantity of the poison which comes into direct contact with the blood is
+large, there may occur hæmolysis and thrombosis of the vessels.
+
+On the other hand, check experiments were carried out, using similar
+extracts of many common European spiders of the genera _Tegenaria_,
+_Drassus_, _Agelena_, _Eucharia_ and _Argyroneta_, as well as the
+Russian tarantula, _Lycosa singoriensis_. In no other case was the
+effect on experimental animals comparable to the _Latrodectus_ extract.
+
+Kobert concludes that in its chemical nature the poison is neither an
+alkaloid, nor a glycoside, nor an acid, but a toxalbumen, or poisonous
+enzyme which is very similar to certain other animal poisons, notably
+that of the scorpion.
+
+[Illustration: 9. Latrodectus mactans; (_a_) female, x 3; (_b_) venter
+of female; (_c_) dorsum of male. After Comstock.]
+
+The genus _Latrodectus_ is represented in the United States by at least
+two species, _L. mactans_ and _L. geometricus_. Concerning _L. mactans_
+there are very circumstantial accounts of serious injury and even death
+in man[B]. _Latrodectus mactans_ is coal black, marked with red or
+yellow or both. It has eight eyes, which are dissimilar in color and
+are distinctly in front of the middle of the thorax, the lateral eyes of
+each side widely separate. The tarsus of the fourth pair of legs has a
+number of curved setæ in a single series. It has on the ventral side of
+its abdomen an hour-glass shaped spot. The full-grown female is about
+half an inch in length. Its globose abdomen is usually marked with one
+or more red spots dorsally along the middle line. The male is about half
+as long but has in addition to the dorsal spots, four pairs of stripes
+along the sides. Immature females resemble the male in coloring (fig.
+9).
+
+Regarding the distribution of _Latrodectus mactans_, Comstock states
+that: "Although it is essentially a Southern species, it occurs in
+Indiana, Ohio, Pennsylvania, New Hampshire, and doubtless other of the
+Northern States." _L. geometricus_ has been reported from California.
+
+
+OTHER VENOMOUS SPIDERS--While conclusive evidence regarding the venomous
+nature of spiders is meager and relates almost wholly to that of the
+genus _Latrodectus_, the group is a large one and we are not justified
+in dismissing arbitrarily, all accounts of injury from their bites.
+Several species stand out as especially needing more detailed
+investigation.
+
+_Chiracanthium nutrix_ is a common European species of the family
+Clubionidæ, concerning which there is much conflicting testimony. Among
+the reports are two by distinguished scientists whose accounts of
+personal experiences cannot be ignored. A. Forel allowed a spider of
+this species to bite him and not only was the pain extreme, but the
+general symptoms were so severe that he had to be helped to his house.
+The distinguished arachnologist, Bertkau reports that he, himself, was
+bitten and that an extreme, burning pain spread almost instantaneously
+over the arm and into the breast. There were slight chills the same day
+and throbbing pain at the wound lasted for days. While this particular
+species is not found in the United States, there are two other
+representatives of the genus and it is possible that they possess the
+same properties. We are unaware of any direct experimental work on the
+poison.
+
+_Epeira diadema_, of Europe, belongs to a wholly different group, that
+of the orb-weavers, but has long been reputed venomous. Kobert was able
+to prepare from it an extract whose effects were very similar to that
+prepared from _Latrodectus_, though feebler in its action. Under
+ordinary circumstances this spider is unable to pierce the skin of man
+and though Kobert's results seem conclusive, the spider is little to be
+feared.
+
+_Phidippus audax_ (_P. tripunctatus_) is one of our largest Attids, or
+jumping spiders. The late Dr. O. Lugger describes a case of severe
+poisoning from the bite of this spider and though details are lacking,
+it is quite possible that this and other large species of the same
+group, which stalk their prey, may possess a more active poison than
+that of web-building species.
+
+
+SUMMARY--It is clearly established that our common spiders are not to be
+feared and that the stories regarding their virulence are almost wholly
+without foundation. On the other hand, the chances of secondary
+infection from the bites of some of the more powerful species are not to
+be ignored.
+
+Probably all species possess a toxin secreted by the poison gland,
+virulent for insects and other normal prey of the spiders, but with
+little or no effect on man.
+
+There are a very few species, notably of the genus _Latrodectus_, and
+possibly including the European _Chiracanthium nutrix_ and _Epeira
+diadema_, which possess, in addition, a toxalbumen derived from the
+general body tissue, which is of great virulence and may even cause
+death in man and the higher animals.
+
+[Illustration: 10. A whip-scorpion (Mastigoproctus giganteus). Half
+natural size. After Comstock.]
+
+
+THE PEDIPALPIDA OR WHIP-SCORPIONS
+
+The tailed whip-scorpions, belonging to the family Thelyphonidæ, are
+represented in the United States by the giant whip-scorpion
+_Mastigoproctus giganteus_ (fig. 10), which is common in Florida, Texas
+and some other parts of the South. In Florida, it is locally known as
+the "grampus" or "mule-killer" and is very greatly feared. There is no
+evidence that these fears have any foundation, and Dr. Marx states that
+there is neither a poison gland nor a pore in the claw of the
+chelicera.
+
+
+THE SCORPIONIDA, OR TRUE SCORPIONS
+
+The true scorpions are widely distributed throughout warm countries and
+everywhere bear an evil reputation. According to Comstock (1912), about
+a score of species occur in the Southern United States. These are
+comparatively small forms but in the tropics members of this group may
+reach a length of seven or eight inches. They are pre-eminently
+predaceous forms, which lie hidden during the day and seek their prey by
+night.
+
+[Illustration: 11. A true scorpion. After Comstock.]
+
+The scorpions (fig. 11) possess large pedipalpi, terminated by strongly
+developed claws, or chelæ. They may be distinguished from all other
+Arachnids by the fact that the distinctly segmented abdomen is divided
+into a broad basal region of seven segments and a terminal, slender,
+tail-like division of five distinct segments.
+
+The last segment of the abdomen, or telson, terminates in a
+ventrally-directed, sharp spine, and contains a pair of highly developed
+poison glands. These glands open by two small pores near the tip of the
+spine. Most of the species when running carry the tip of the abdomen
+bent upward over the back, and the prey, caught and held by the
+pedipalpi, is stung by inserting the spine of the telson and allowing it
+to remain for a time in the wound.
+
+The glands themselves have been studied in _Prionurus citrinus_ by
+Wilson (1904). He found that each gland is covered by a sheet of muscle
+on its mesal and dorsal aspects, which may be described as the
+_compressor muscle_. The muscle of each side is inserted by its edge
+along the ventral inner surface of the chitinous wall of the telson,
+close to the middle line, and by a broader insertion laterally. A layer
+of fine connective tissue completely envelops each gland and forms the
+basis upon which the secreting cells rest. The secreting epithelium is
+columnar; and apparently of three different types of cells.
+
+1. The most numerous have the appearance of mucous cells, resembling the
+goblet cells of columnar mucous membranes. The nucleus, surrounded by a
+small quantity of protoplasm staining with hæmatoxylin, lies close to
+the base of the cell.
+
+2. Cells present in considerable numbers, the peripheral portions of
+which are filled with very numerous fine granules, staining with acid
+dyes such as methyl orange.
+
+3. Cells few in number, filled with very large granules, or irregular
+masses of a substance staining with hæmatoxylin.
+
+The poison, according to Kobert (1893), is a limpid, acid-reacting
+fluid, soluble in water but insoluble in absolute alcohol and ether.
+There are few data relative to its chemical nature. Wilson (1901) states
+that a common Egyptian species, _Buthus quinquestriatus_, has a specific
+gravity of 1.092, and contains 20.3% of solids and 8.4% ash.
+
+The venom of different species appears to differ not only quantitatively
+but qualitatively. The effects of the bite of the smaller species of the
+Southern United States may be painful but there is no satisfactory
+evidence that it is ever fatal. On the other hand, certain tropical
+species are exceedingly virulent and cases of death of man from the bite
+are common.
+
+In the case of _Buthus quinquestriatus_, Wilson (1904) found the
+symptoms in animals to be hypersecretion, salivation and lachrymation,
+especially marked, convulsions followed by prolonged muscular spasm;
+death from asphyxia. The temperature shows a slight, rarely
+considerable, rise. Rapid and considerable increase of blood-pressure
+(observed in dogs) is followed by a gradual fall with slowing of the
+heart-beat. The coagulability of the blood is not affected.
+
+An interesting phase of Wilson's work was the experiments on desert
+mammals. The condition under which these animals exist must frequently
+bring them in contact with scorpions, and he found that they possess a
+degree of immunity to the venom sufficient at least to protect them from
+the fatal effects of the sting.
+
+As far as concerns its effect on man, Wilson found that much depended
+upon the age. As high as 60 per cent of the cases of children under
+five, resulted fatally. Caroroz (1865), states that in a Mexican state
+of 15,000 inhabitants, the scorpions were so abundant and so much feared
+that the authorities offered a bounty for their destruction. A result
+was a large number of fatalities, over two hundred per year. Most of the
+victims were children who had attempted to collect the scorpions.
+
+The treatment usually employed in the case of bites by the more
+poisonous forms is similar to that for the bite of venomous snakes.
+First, a tight ligature is applied above the wound so as to stop the
+flow of blood and lymph from that region. The wound is then freely
+excised and treated with a strong solution of permanganate of potash, or
+with lead and opium lotion.
+
+In recent years there have been many attempts to prepare an antivenom,
+or antiserum comparable to what has been used so effectively in the case
+of snake bites. The most promising of these is that of Todd (1909),
+produced by the immunization of suitable animals. This antivenom proved
+capable of neutralizing the venom when mixed _in vitro_ and also acts
+both prophylactically and curatively in animals. Employed curatively in
+man, it appears to have a very marked effect on the intense pain
+following the sting, and the evidence so far indicates that its prompt
+use greatly reduces the chance of fatal results.
+
+
+THE SOLPUGIDA, OR SOLPUGIDS
+
+The SOLPUGIDA are peculiar spider-like forms which are distinguished
+from nearly all other arachnids by the fact that they possess no true
+cephalothorax, the last two leg-bearing segments being distinct,
+resembling those of the abdomen in this respect. The first pair of legs
+is not used in locomotion but seemingly functions as a second pair of
+pedipalpi. Figure 12 illustrates the striking peculiarities of the
+group. They are primarily desert forms and occur in the warm zones of
+all countries. Of the two hundred or more species, Comstock lists twelve
+as occurring in our fauna. These occur primarily in the southwest.
+
+[Illustration: 12. A solpugid (Eremobates cinerea). After Comstock.]
+
+The Solpugida have long borne a bad reputation and, regarding virulence,
+have been classed with the scorpions. Among the effects of their bites
+have been described painful swelling, gangrene, loss of speech, cramps,
+delirium, unconsciousness and even death. Opposed to the numerous loose
+accounts of poisoning, there are a number of careful records by
+physicians and zoölogists which indicate clearly that the effects are
+local and though they may be severe, they show not the slightest symptom
+of direct poisoning.
+
+More important in the consideration of the question is the fact that
+there are neither poison glands nor pores in the fangs for the exit of
+any poisonous secretion. This is the testimony of a number of prominent
+zoölogists, among whom is Dr. A. Walter, who wrote to Kobert at length
+on the subject and whose conclusions are presented by him.
+
+However, it should be noted that the fangs are very powerful and are
+used in such a manner that they may inflict especially severe wounds.
+Thus, there may be more opportunity for secondary infection than is
+usual in the case of insect wounds.
+
+The treatment of the bite of the Solpugida is, therefore, a matter of
+preventing infection. The wound should be allowed to bleed freely and
+then washed out with a 1:3000 solution of corrosive sublimate, and, if
+severe, a wet dressing of this should be applied. If infection takes
+place, it should be treated in the usual manner, regardless of its
+origin.
+
+
+THE ACARINA, OR MITES AND TICKS
+
+A number of the parasitic Acarina evidently secrete a specific poison,
+presumably carried by the saliva, but in most cases its effect on man is
+insignificant. There is an abundant literature dealing with the
+poisonous effect of the bite of these forms, especially the ticks, but
+until recently it has been confused by failure to recognize that various
+species may transmit diseases of man, rather than produce injury through
+direct poisoning. We shall therefore discuss the Acarina more especially
+in subsequent chapters, dealing with parasitism and with disease
+transmission.
+
+Nevertheless, after the evidence is sifted, there can be no doubt that
+the bites of certain ticks may occasionally be followed by a direct
+poisoning, which may be either local or general in its effects. Nuttall
+(1908) was unable to determine the cause of the toxic effect, for, in
+_Argas persicus_, the species most often implicated, he failed to get
+the slightest local or general effect on experimental animals, from the
+injection of an emulsion prepared by crushing three of the ticks.
+
+It seems clearly established that the bite of certain ticks may cause a
+temporary paralysis, or even complete paralysis, involving the organs of
+respiration or the heart, and causing death. In 1912, Dr. I. U. Temple,
+of Pendleton, Oregon, reported several cases of what he called "acute
+ascending paralysis" associated with the occurrence of ticks on the head
+or the back of the neck. A typical severe case was that of a six year
+old child, who had retired in her usual normal health. The following
+morning upon arising she was unable to stand on her feet. She exhibited
+paralysis extending to the knees, slight temperature, no pain, sensory
+nerves normal, motor nerves completely paralyzed, reflexes absent. The
+following day the paralysis had extended to the upper limbs, and before
+night of the third day the nerves of the throat (hypoglossal) were
+affected. The thorax and larynx were involved, breathing was labored,
+she was unable to swallow liquids, phonation was impossible and she
+could only make low, guttural sounds. At this stage, two ticks, fully
+distended with blood, were found over the junction of the spinal column
+with the occipital bones in the hollow depression. They were removed by
+the application of undiluted creoline. Though the child's life was
+despaired of, by the following morning she was very much improved. By
+evening she was able to speak. The paralysis gradually receded,
+remaining longest in the feet, and at the end of one week the patient
+was able to go home.
+
+There was some doubt as to the exact species of tick implicated in the
+cases which Dr. Temple reported, although the evidence pointed strongly
+to _Dermacentor venustus_.[C] Somewhat later, Hadwen (1913) reported
+that "tick paralysis" occurs in British Columbia, where it affects not
+only man, but sheep and probably other animals. It is caused by the
+bites of _Dermacentor venustus_ and was experimentally produced in lambs
+and a dog (Hadwen and Nuttall, 1913). It is only when the tick begins to
+engorge or feed rapidly, some days after it has become attached, that
+its saliva produces pathogenic effects.
+
+Ulceration following tick bite is not uncommon. In many of the instances
+it is due to the file-like hypostome, with its recurved teeth, being
+left in the wound when the tick is forcibly pulled off.
+
+
+THE MYRIAPODA, OR CENTIPEDES AND MILLIPEDES
+
+The old class, Myriapoda includes the DIPLOPODA, or millipedes, and the
+CHILOPODA, or centipedes. The present tendency is to raise these groups
+to the rank of classes.
+
+
+The Diplopoda
+
+The DIPLOPODA, or millipedes (fig. 13), are characterized by the
+presence of two pairs of legs to a segment. The largest of our local
+myriapods belong to this group. They live in moist places, feeding
+primarily on decaying vegetable matter, though a few species
+occasionally attack growing plants.
+
+[Illustration: 13. A millipede. After Comstock.]
+
+The millipedes are inoffensive and harmless. _Julus terrestris_, and
+related species, when irritated pour out over the entire body a
+yellowish secretion which escapes from cutaneous glands. It is volatile,
+with a pungent odor, and Phisalix (1900) has shown that it is an active
+poison when injected into the blood of experimental animals. This,
+however, does not entitle them to be considered as poisonous arthropods,
+in the sense of this chapter, any more than the toad can be considered
+poisonous to man because it secretes a venom from its cutaneous glands.
+
+
+The Chilopoda
+
+[Illustration: 14. Two common centipedes.
+
+(_a_) Lithobius forficatus. After Comstock.
+
+(_b_) Scutigera forceps. Natural size; after Howard.]
+
+The CHILOPODA, or centipedes (fig. 14), unlike the millipedes, are
+predaceous forms, and possess well developed poison glands for killing
+their prey. These glands are at the base of the first pair of legs
+(fig. 15), which are bent forward so as to be used in holding their
+prey. The legs terminate in a powerful claw, at the tip of which is the
+outlet of the poison glands.
+
+The poison is a limpid, homogeneous, slightly acid fluid, which
+precipitates in distilled water. Briot (1904) extracted it from the
+glands of _Scolopendra morsitans_, a species common in central France,
+and found that it was actively venomous for the ordinary experimental
+animals. A rabbit of two kilograms weight received an injection of three
+cubic centimeters in the vein of the ear and died in a minute. A white
+rat, weighing forty-eight grams, received one and a half cubic
+centimeters in the hind leg. There was an almost immediate paralysis of
+the leg and marked necrosis of the tissues.
+
+[Illustration: 15. Mandible of Scolopendra cingulata showing venom
+gland. After Dubosq.]
+
+As for the effect on man, there is little foundation for the fear with
+which centipedes are regarded. Our native species produce, at most,
+local symptoms,--sometimes severe local pain and swelling,--but there is
+no authentic record of fatal results. In the tropics, some of the
+species attain a large size, _Scolopendra gigantea_ reaching a length of
+nearly a foot. These forms are justly feared, and there is good evidence
+that death sometimes, though rarely, results from their bite.
+
+One of the most careful accounts of death from the sting of the scorpion
+is that of Linnell, (1914), which relates to a comparatively small
+Malayan species, unfortunately undetermined. The patient, a coolie, aged
+twenty, was admitted to a hospital after having been stung two days
+previously on the left heel. For cure, the other coolies had made him
+eat the head of the scorpion. On admission, the patient complained of
+"things creeping all over the body". Temp. 102.8°. On the fourth day he
+had paralysis of the legs, and on the fifth day motor paralysis to the
+umbilicus, sensation being unaltered. On the sixth day there was
+retention of the urine and on the ninth day (first test after third day)
+sugar was present. On the thirteenth day the patient became comatose,
+but could be roused to eat and drink. The temperature on the following
+day fell below 95° and the patient was still comatose. Death fifteenth
+day.
+
+Examination of the spinal (lumbar) cord showed acute disseminated
+myelitis. In one part there was an acute destruction of the anterior
+horn and an infiltration of round cells. In another portion Clarke's
+column had been destroyed. The perivascular sheaths were crowded with
+small round cells and the meninges were congested. Some of the cells of
+the anterior horn were swollen and the nuclei eccentric; chromatolysis
+had occurred in many of them.
+
+As for treatment, Castellani and Chalmers (1910), recommend bathing the
+part well with a solution of ammonia (one in five, or one in ten). After
+bathing, apply a dressing of the same alkali or, if there is much
+swelling and redness, an ice-bag. If necessary, hypodermic injections of
+morphine may be given to relieve the pain. At a later period
+fomentations may be required to reduce the local inflammation.
+
+
+THE HEXAPODA OR TRUE INSECTS
+
+There are a number of HEXAPODA, or true insects, which are, in one way
+or another, poisonous to man. These belong primarily to the orders
+Hemiptera, or true bugs; Lepidoptera, or butterflies and moths (larval
+forms); Diptera, or flies; Coleoptera, or beetles; and Hymenoptera, or
+ants, bees, and wasps. There are various ways in which they may be
+poisonous.
+
+1. _Piercing_ or _biting_ forms may inject an irritating or poisonous
+saliva into the wound caused by their mouth-parts.
+
+2. _Stinging forms_ may inject a poison, from glands at the caudal end
+of the abdomen, into wounds produced by a specially modified ovipositer,
+the _sting_.
+
+3. _Nettling_ properties may be possessed by the hairs of the insect.
+
+4. _Vescicating_, or _poisonous blood plasma_, or _body fluids_ are
+known to exist in a large number of species and may, under exceptional
+circumstances, affect man.
+
+For convenience of discussion, we shall consider poisonous insects under
+these various headings. In this, as in the preceding discussion, no
+attempt will be made to give an exhaustive list of the poisonous forms.
+Typical instances will be selected and these will be chosen largely from
+North American species.
+
+
+PIERCING OR BITING INSECTS POISONOUS TO MAN
+
+
+HEMIPTERA
+
+Several families of the true bugs include forms which, while normally
+inoffensive, are capable of inflicting painful wounds on man. In these,
+as in all of the Hemiptera, the mouth-parts are modified to form an
+organ for piercing and sucking. This is well shown by the accompanying
+illustration (fig. 16).
+
+The upper lip, or _labrum_, is much reduced and immovable, the lower
+lip, or _labium_, is elongated to form a jointed sheath, within which
+the lance-like mandibles and maxillæ are enclosed. The mandibles are
+more or less deeply serrate, depending on the species concerned.
+
+[Illustration: 16. Beak of hemipteron.]
+
+The poison is elaborated by the salivary glands, excepting, possibly, in
+_Belostoma_ where Locy is inclined to believe that it is secreted by the
+maxillary glands. The salivary glands of the Hemiptera have been the
+subject of much study but the most recent, comprehensive work has been
+done by Bugnion and Popoff, (1908 and 1910) to whose text the reader is
+referred for details.
+
+The Hemiptera have two pairs of salivary glands: the _primary gland_, of
+which the efferent duct leads to the salivary syringe, and the
+_accessory gland_, of which the very long and flexuous duct empties into
+the primary duct at its point of insertion. Thus, when one observes the
+isolated primary gland it appears as though it had efferent ducts
+inserted at the same point. In _Nepa_ and the _Fulgoridæ_ there are two
+accessory glands and therefore apparently three ducts at the same point
+on the primary gland. The _ensemble_ differs greatly in appearance in
+different species but we shall show here Bugnion and Popoff's figure of
+the apparatus of _Notonecta maculata_, a species capable of inflicting a
+painful bite on man (fig. 17).
+
+[Illustration: 17. Salivary glands of Notonecta maculata. After Bugnion
+and Popoff.]
+
+[Illustration: 18. Pharyngeal syringe or salivary pump of Fulgora
+maculata. After Bugnion and Popoff.]
+
+[Illustration: 19. Heteroptera, (_a_) Melanolestes picipes; (_b_)
+Notonecta undulata; (_c_, _d_) Aradus robustus (_c_) adult, (_d_) nymph,
+much enlarged; (_e_) Arilus cristatus; (_f_) Belostoma americana; (_g_)
+Nabis (Coriscus) subcoleoptratus, enlarged; (_h_) Cimex lectularius,
+(_i_) Oeciacus vicarius, much enlarged; (_j_) Lyctocoris fitchii, much
+enlarged. After Lugger.]
+
+Accessory to the salivary apparatus there is on the ventral side of the
+head, underneath the pharynx, a peculiar organ which the Germans have
+called the "Wanzenspritze," or syringe. The accompanying figure of the
+structure in _Fulgora maculata_ (fig. 18) shows its relation to the
+ducts of the salivary glands and to the beak. It is made up of a
+dilatation forming the body of the pump, in which there is a chitinous
+piston. Attached to the piston is a strong retractor muscle. The
+function of the salivary pump is to suck up the saliva from the salivary
+ducts and to force it out through the beak.
+
+Of the Hemiptera reported as attacking man, we shall consider briefly
+the forms most frequently noted.
+
+
+The NOTONECTIDÆ, or _back swimmers_, (fig. 19_b_) are small, aquatic
+bugs that differ from all others in that they always swim on their
+backs. They are predaceous; feeding on insects and other small forms.
+When handled carelessly they are able to inflict a painful bite, which
+is sometimes as severe as the sting of a bee. In fact, they are known in
+Germany as "Wasserbienen."
+
+
+The BELOSTOMATIDÆ, or _giant water bugs_, (fig. 19_f_) include the
+largest living Hemiptera. They are attracted to lights and on account of
+the large numbers which swarm about the electric street lamps in some
+localities they have received the popular name "electric light bugs."
+Our largest representatives in the northern United States belong to the
+two genera _Belostoma_ and _Banacus_, distinguished from each other by
+the fact that _Belostoma_ has a groove on the under side of the femur of
+the front leg, for the reception of the tibia.
+
+The salivary glands of Belostoma were figured by Leidy (1847) and later
+were studied in more detail by Locy (1884). There are two pairs of the
+glands, those of one pair being long and extending back as far as the
+beginning of the abdomen, while the others are about one-fourth as long.
+They lie on either side of the Å“sophagus. On each side of the
+Å“sophagus there is a slender tube with a sigmoid swelling which may
+serve as a poison reservoir. In addition to this salivary system, there
+is a pair of very prominent glands on the ventral side of the head,
+opening just above the base of the beak. These Locy has called the
+"cephalic glands" and he suggests that they are the source of the
+poison. They are the homologues of the maxillary glands described for
+other Hemiptera, and it is by no means clear that they are concerned
+with the production of venom. It seems more probable that in
+_Belostoma_, as in other Hemiptera, it is produced by the salivary
+glands, though the question is an open one.
+
+The Belostomatidæ feed not only on insects, but on small frogs, fish,
+salamanders and the like. Matheson (1907) has recorded the killing of a
+good-sized bird by _Belostoma americana_. A woodpecker, or flicker, was
+heard to utter cries of distress, and fluttered and fell from a tree. On
+examination it was found that a bug of this species had inserted its
+beak into the back part of the skull and was apparently busily engaged
+in sucking the blood or brains of the bird. Various species of
+_Belostoma_ have been cited as causing painful bites in man. We can
+testify from personal experience that the bite of _Belostoma americana_
+may almost immediately cause severe, shooting pains that may extend
+throughout the arm and that they may be felt for several days.
+
+[Illustration: 20. Reduvius (Opsicœtus) personatus. (×2).]
+
+Relief from the pain may be obtained by the use of dilute ammonia, or a
+menthol ointment. In the not uncommon case of secondary infection the
+usual treatment for that should be adopted.
+
+[Illustration: 21. (_a_) Reduvius personatus, nymph. Photograph by M. V.
+S.]
+
+
+The REDUVIIDÆ, or _assassin-bugs_ are capable of inflicting very painful
+wounds, as most collectors of Hemiptera know to their sorrow. Some
+species are frequently to be found in houses and outhouses and Dr.
+Howard suggests that many of the stories of painful spider bites relate
+to the attack of these forms.
+
+[Illustration: 21. (_b_) Reduvius personatus, adult (×2) Photograph by
+M. V. S.]
+
+An interesting psychological study was afforded in the summer of 1899,
+by the "kissing-bug" scare which swept over the country. It was reported
+in the daily papers that a new and deadly bug had made its appearance,
+which had the unpleasant habit of choosing the lips or cheeks for its
+point of attack on man. So widespread were the stories regarding this
+supposedly new insect that station entomologists all over the country
+began to receive suspected specimens for identification. At Cornell
+there were received, among others, specimens of stone-flies, may-flies
+and even small moths, with inquiries as to whether they were
+"kissing-bugs."
+
+[Illustration: 22. Rasahus biguttatus. (×2). After Howard.]
+
+Dr. L. O. Howard has shown that the scare had its origin in newspaper
+reports of some instances of bites by either _Melanolestes picipes_
+(fig. 19a) or _Opsicoetes personatus_ (fig. 20), in the vicinity of
+Washington, D. C. He then discusses in considerable detail the more
+prominent of the Reduviidæ which, with greater or less frequency pierce
+the skin of human beings. These are _Opsicoetes personatus_,
+_Melanolestes picipes_, _Coriscus subcoleoptratus_ (fig. 19_g_),
+_Rasahus thoracicus_, _Rasahus biguttatus_ (fig. 22), _Conorhinus
+sanguisugus_ (fig. 71), and _Melanolestes abdominalis_ (fig. 23).
+
+[Illustration: 23. Melanolestes abdominalis (×2). After Marlatt.]
+
+One of the most interesting of these species is _Reduvius personatus_,
+(= _Opsicœtus personatus_), which is popularly known as the "masked
+bed-bug hunter." It owes this name to the fact that the immature nymphs
+(fig. 21) have their bodies and legs completely covered by dust and
+lint, and that they are supposed to prey upon bed-bugs. LeConte is
+quoted by Howard as stating that "This species is remarkable for the
+intense pain caused by its bite. I do not know whether it ever willingly
+plunges its rostrum into any person, but when caught, or unskilfully
+handled it always stings. In this case the pain is almost equal to the
+bite of a snake, and the swelling and irritation which result from it
+will sometimes last for a week."
+
+A species which very commonly attacks man is _Conorhinus sanguisugus_,
+the so-called "big bed-bug" of the south and southern United States. It
+is frequently found in houses and is known to inflict an exceedingly
+painful bite. As in the case of a number of other predaceous Hemiptera,
+the salivary glands of these forms are highly developed. The effect of
+the bite on their prey and, as Marlatt has pointed out, the constant and
+uniform character of the symptoms in nearly all cases of bites in man,
+clearly indicate that their saliva contains a specific substance. No
+satisfactory studies of the secretions have been made. On the other
+hand, Dr. Howard is doubtless right in maintaining that the very serious
+results which sometimes follow the bite are due to the introduction of
+extraneous poison germs. This is borne out by the symptoms of most of
+the cases cited in literature and also by the fact that treatment with
+corrosive sublimate, locally applied to the wound, has yielded favorable
+results.
+
+
+OTHER HEMIPTERA REPORTED AS POISONOUS TO MAN--A large number of other
+Hemiptera have been reported as attacking man. Of these, there are
+several species of Lygæidæ, Coreidæ, and Capsidæ. Of the latter, _Lygus
+pratensis_, the tarnished plant-bug, is reported by Professor Crosby as
+sucking blood. _Orthotylus flavosparsus_ is another Capsid which has
+been implicated. _Empoasca mali_ and _Platymetopius acutus_ of the
+Jassidæ have also been reported as having similar habits.
+
+Whenever the periodical cicada or "seventeen-year locust" becomes
+abundant, the newspapers contain accounts of serious results from its
+bites. The senior author has made scores of attempts to induce this
+species to bite and only once successfully. At that time the bite was in
+no wise more severe than a pin-prick. A student in our department
+reports a similar experience. There is no case on record which bears
+evidence of being worthy of any credence, whatsoever.
+
+Under the heading of poisonous Hemiptera we might consider the bed-bugs
+and the lice. These will be discussed later, as parasites and as
+carriers of disease, and therefore need only be mentioned here.
+
+
+DIPTERA
+
+Several species of blood-sucking Diptera undoubtedly secrete a saliva
+possessing poisonous properties. Chief among these are the Culicidæ, or
+mosquitoes, and the Simuliidæ, or black-flies. As we shall consider
+these forms in detail under the heading of parasitic species and
+insects transmitting disease, we shall discuss here only the poison of
+the mosquitoes.
+
+It is well known that mosquitoes, when they bite, inject into the wound
+a minute quantity of poison. The effect of this varies according to the
+species of mosquito and also depends very much on the susceptibility of
+the individual. Soon after the bite a sensation of itching is noticed
+and often a wheal, or eminence, is produced on the skin, which may
+increase to a considerable swelling. The scratching which is induced may
+cause a secondary infection and thus lead to serious results. Some
+people seem to acquire an immunity against the poison.
+
+The purpose of this irritating fluid may be, as Reaumur suggested, to
+prevent the coagulation of the blood and thus not only to cause it to
+flow freely when the insect bites but to prevent its rapid coagulation
+in the stomach. Obviously, it is not developed as a protective fluid,
+and its presence subjects the group to the additional handicap of the
+vengeance of man.
+
+[Illustration: 24. Diagram of a longitudinal section of a mosquito.]
+
+As to the origin of the poison, there has been little question, until
+recent years, that it was a secretion from the salivary glands.
+Macloskie (1888) showed that each gland is subdivided into three lobes,
+the middle of which differs from the others in having evenly granulated
+contents and staining more deeply than the others (fig. 24). This middle
+lobe he regarded as the source of the poison. Bruck, (1911), by the use
+of water, glycerine, chloroform, and other fluids, extracted from the
+bodies of a large number of mosquitoes a toxine which he calls
+_culicin_. This he assumes comes from the salivary glands. Animal
+experimentation showed that this extract possessed hemolytic powers.
+Inoculated into the experimenter's own skin it produced lesions which
+behaved exactly as do those of mosquito bites.
+
+Similarly, most writers on the subject have concurred with the view that
+the salivary glands are the source of the poison. However, recent work,
+especially that of Nuttall and Shipley (1903), and Schaudinn (1904), has
+shown that the evidence is by no means conclusive. Nuttall dissected out
+six sets (thirty-six acini) of glands from freshly killed _Culex
+pipiens_ and placed them in a drop of salt solution. The drop was
+allowed to dry, it being thought that the salt crystals would facilitate
+the grinding up of the glands with the end of a small glass rod, this
+being done under microscopic control. After grinding up, a small drop of
+water was added of the size of the original drop of saline, and an equal
+volume of human blood taken from the clean finger-tip was quickly mixed
+therewith, and the whole drawn up into a capillary tube. Clotting was
+not prevented and no hemolysis occurred. Salivary gland emulsion added
+to a dilute suspension of corpuscles did not lead to hemolysis. This
+experiment was repeated a number of times, with slight modification, but
+with similar results. The data obtained from the series "do not support
+the hypothesis that the salivary glands, at any rate in _Culex pipiens_,
+contain a substance which prevents coagulation."
+
+Much more detailed, and the more important experiments made along this
+line, are those of Schaudinn (1904). The results of these experiments
+were published in connection with a technical paper on the alternation
+of generations and of hosts in _Trypanosoma_ and _Spirochæta_, and for
+this reason seem to have largely escaped the notice of entomologists.
+They are so suggestive that we shall refer to them in some detail.
+
+Schaudinn observed that the three Å“sophageal diverticula (commonly,
+but incorrectly, known as the "sucking stomach") (fig. 24) usually
+contain large bubbles of gas and in addition, he always found yeast
+cells. On the ground of numerous observations, Schaudinn was convinced
+that these yeast plants are normal and constant commensals of the
+insect. He regarded them as the cause of the gas bubbles to be found in
+diverticula. It was found that as the insect fed, from time to time the
+abdomen underwent convulsive contractions which resulted in the emptying
+of the Å“sophageal diverticula and the salivary glands through blood
+pressure.
+
+In order to test the supposed toxic action of the salivary glands,
+Schaudinn repeatedly introduced them under his skin and that of his
+assistant, in a drop of salt solution, and never obtained a suggestion
+of the irritation following a bite of the insect, even though the glands
+were carefully rubbed to fragments after their implantation. Like
+Nuttall, he failed to get satisfactory evidence that the secretion of
+the salivary glands retarded coagulation of the blood.
+
+He then carefully removed the Å“sophageal diverticula with their
+content of yeast and introduced them into an opening in the skin of the
+hand. Within a few seconds there was noticeable the characteristic
+itching irritation of the mosquito bite; and in a short time there
+appeared reddening and typical swelling. This was usually much more
+severe than after the usual mosquito bite, and the swelling persisted
+and itched longer. This was because by the ordinary bite of the mosquito
+most of the yeast cells are again sucked up, while in these experiments
+they remained in the wound. These experiments were repeated a number of
+times on himself, his assistant and others, and always with the same
+result. From them Schaudinn decided that the poisonous action of the
+mosquito bite is caused by an enzyme from a commensal fungus. These
+conclusions have not, as yet, been satisfactorily tested.
+
+Relief from the effect of the mosquito bite may be obtained by bathing
+the swellings with weak ammonia or, according to Howard, by using moist
+soap. The latter is to be rubbed gently on the puncture and is said to
+speedily allay the irritation. Howard also quotes from the _Journal of
+Tropical Medicine and Hygiene_ to the effect that a few drops of a
+solution of thirty to forty grains of iodine to an ounce of saponated
+petroleum rubbed into the mosquito bite, or wasp sting, allay the pain
+instantaneously.
+
+Methods of mosquito control will be discussed later, in considering
+these insects as parasites and as carriers of disease.
+
+
+STINGING INSECTS
+
+The stinging insects all belong to the order HYMENOPTERA. In a number of
+families of this group the ovipositor is modified to form a sting and is
+connected with poison-secreting glands. We shall consider the apparatus
+of the honey-bee and then make briefer reference to that of other forms.
+
+
+APIS MELLIFICA, THE HONEY BEE--The sting of the worker honey-bee is
+situated within a so-called sting chamber at the end of the abdomen.
+This chamber is produced by the infolding of the greatly reduced and
+modified eighth, ninth and tenth abdominal segments into the seventh.[D]
+From it the dart-like sting can be quickly exserted.
+
+The sting (fig. 25) is made up of a central shaft, ventro-laterad of
+which are the paired _lancets_, or darts, which are provided with sharp,
+recurved teeth. Still further laterad lie the paired whitish,
+finger-like _sting palpi_. Comparative morphological as well as
+embryological studies have clearly established that these three parts
+correspond to the three pairs of gonopophyses of the ovipositor of more
+generalized insects.
+
+[Illustration: 25. Sting of a honey bee. _Psn Sc_, base of acid poison
+gland; _B Gl_, alkaline poison gland; _Stn Plp_, sting palpi; _Sh B_,
+bulb of sting; _Sh A_, basal arm; _Lct_, lancets or darts; _Sh s_, shaft
+of sting. Modified from Snodgrass.]
+
+[Illustration: 26. Poison apparatus of a honey bee. Modified from
+Snodgrass.]
+
+An examination of the internal structures (fig. 26) reveals two distinct
+types of poison glands, the acid-secreting and the alkaline-secreting
+glands, and a prominent poison reservoir. In addition, there is a small
+pair of accessory structures which have been called lubricating glands,
+on account of the supposed function of their product. The acid-secreting
+gland empties into the distal end of the poison reservoir which in turn
+pours the secretion into the muscular bulb-like enlargement at the base
+of the shaft. The alkaline secreting gland empties into the bulb ventrad
+of the narrow neck of the reservoir.
+
+The poison is usually referred to as formic acid. That it is not so
+easily explained has been repeatedly shown and is evidenced by the
+presence of the two types of glands. Carlet maintains that the product
+of either gland is in itself innocent,--it is only when they are
+combined that the toxic properties appear.
+
+The most detailed study of the poison of the honey-bee is that of Josef
+Langer (1897), who in the course of his work used some 25,000 bees.
+Various methods of obtaining the active poison for experimental purposes
+were used. For obtaining the pure secretion, bees were held in the
+fingers and compressed until the sting was exserted, when a clear drop
+of the poison was visible at its tip. This was then taken up in a
+capillary tube or dilute solutions obtained by dipping the tip of the
+sting into a definite amount of distilled water.
+
+An aqueous solution of the poison was more readily obtained by pulling
+out the sting and poison sacs by means of forceps, and grinding them up
+in water. The somewhat clouded fluid was then filtered one or more
+times. For obtaining still greater quantities, advantage was taken of
+the fact that while alcohol coagulates the poison, the active principle
+remains soluble in water. Hence the stings with the annexed glands where
+collected in 96 per cent alcohol, after filtering off of the alcohol
+were dried at 40° C., then rubbed to a fine powder and this was
+repeatedly extracted with water. Through filtering of this aqueous
+extract there was obtained a yellowish-brown fluid which produced the
+typical reactions, according to concentration of the poison.
+
+The freshly expelled drop of poison is limpid, of distinct acid
+reaction, tastes bitter and has a delicate aromatic odor. On
+evaporation, it leaves a sticky residue, which at 100 degrees becomes
+fissured, and suggests dried gum arabic. The poison is readily soluble
+in water and possesses a specific gravity of 1.1313. On drying at room
+temperature, it leaves a residue of 30 per cent, which has not lost in
+poisonous action or in solubility. In spite of extended experiments,
+Langer was unable to determine the nature of the active principle. He
+showed that it was not, as had been supposed, an albuminous body, but
+rather an organic base.
+
+The pure poison, or the two per cent aqueous solution, placed on the
+uninjured skin showed absolutely no irritating effect, though it
+produced a marked reaction on the mucus membrane of the nose or eye. A
+single drop of one-tenth per cent aqueous solution of the poison brought
+about a typical irritation in the conjunctiva of the rabbit's eye. On
+the other hand, the application of a drop of the poison, or its
+solution, to the slightest break in the skin, or by means of a needle
+piercing the skin, produced typical effects. There is produced a local
+necrosis, in the neighborhood of which there is infiltration of
+lymphocytes, œdema, and hyperæmia.
+
+The effect of the sting on man (fig. 27) is usually transitory but there
+are some individuals who are made sick for hours, by a single sting.
+Much depends, too, on the place struck. It is a common experience that
+an angry bee will attempt to reach the eye of its victim and a sting on
+the lid may result in severe and prolonged swelling. In the case of a
+man stung on the cheek, Legiehn observed complete aphonia and a breaking
+out of red blotches all over the body. A sting on the tongue has been
+known to cause such collateral Å“dema as to endanger life through
+suffocation. Cases of death of man from the attacks of bees are rare but
+are not unknown. Such results are usually from a number of stings but,
+rarely, death has been known to follow a single sting, entering a blood
+vessel of a particularly susceptible individual.
+
+[Illustration: Effect of bee stings. After Root.]
+
+It is clearly established that partial immunity from the effects of the
+poison may be acquired. By repeated injections of the venom, mice have
+been rendered capable of bearing doses that certainly would have killed
+them at first. It is a well-known fact that most bee-keepers become
+gradually hardened to the stings, so that the irritation and the
+swelling become less and less. Some individuals have found this immunity
+a temporary one, to be reacquired each season. A striking case of
+acquired immunity is related by the Roots in their "A B C and X Y Z of
+Bee Culture." The evidence in the case is so clear that it should be
+made more widely available and hence we quote it here.
+
+A young man who was determined to become a bee-keeper, was so
+susceptible to the poison that he was most seriously affected by a
+single sting, his body breaking out with red blotches, breathing growing
+difficult, and his heart action being painfully accelerated. "We finally
+suggested taking a live bee and pressing it on the back of his hand
+until it merely pierced his skin with the sting, then immediately
+brushing off both bee and sting. This was done and since no serious
+effect followed, it was repeated inside of four or five days. This was
+continued for some three or four weeks, when the patient began to have a
+sort of itching sensation all over his body. The hypodermic injections
+of bee-sting poison were then discontinued. At the end of a month they
+were repeated at intervals of four or five days. Again, after two or
+three weeks the itching sensation came on, but it was less pronounced.
+The patient was given a rest of about a month, when the doses were
+repeated as before." By this course of treatment the young man became so
+thoroughly immunized that neither unpleasant results nor swelling
+followed the attacks of the insects and he is able to handle bees with
+the same freedom that any experienced bee-keeper does.
+
+In an interesting article in the _Entomological News_ for November,
+1914, J. H. Lovell calls attention to the fact that "There has been a
+widespread belief among apiarists that a beekeeper will receive more
+stings when dressed in black than when wearing white clothing. A large
+amount of evidence has been published in the various bee journals
+showing beyond question that honey-bees under certain conditions
+discriminate against black. A few instances may be cited in
+illustration. Of a flock of twelve chickens running in a bee-yard seven
+black ones were stung to death, while five light colored ones escaped
+uninjured. A white dog ran among the bee-hives without attracting much
+attention, while at the same time a black dog was furiously assailed by
+the bees. Mr. J. D. Byer, a prominent Canadian beekeeper, relates that a
+black and white cow, tethered about forty feet from an apiary, was one
+afternoon attacked and badly stung by bees. On examination it was found
+that the black spots had five or six stings to one on the white. All
+noticed this fact, although no one was able to offer any explanation. A
+white horse is in much less danger of being stung, when driven near an
+apiary, than a black one. It has, indeed, been observed repeatedly that
+domestic animals of all kinds, if wholly or partially black, are much
+more liable to be attacked by bees, if they wander among the hives, than
+those which are entirely white."
+
+In order to test the matter experimentally, the following series of
+experiments was performed. In the language of the investigator:
+
+"On a clear, warm day in August I dressed wholly in white with the
+exception of a black veil. Midway on the sleeve of my right arm there
+was sewed a band of black cloth ten inches wide. I then entered the
+bee-yard and, removing the cover from one of the hives, lifted a piece
+of comb with both hands and gently shook it. Instantly many of the bees
+flew to the black band, which they continued to attack as long as they
+were disturbed. Not a single bee attempted to sting the left sleeve,
+which was of course entirely white, and very few even alighted upon it."
+
+"This experiment was repeated a second, third and fourth time; in each
+instance with similar results. I estimated the number of bees on the
+band of black cloth at various moments was from thirty to forty; it was
+evident from their behavior that they were extremely irritable. To the
+left white sleeve and other portions of my clothing they paid very
+little attention; but the black veil was very frequently attacked."
+
+"A few days later the experiments were repeated, but the band of black
+cloth, ten inches wide, was sewed around my left arm instead of around
+the right arm as before. When the bees were disturbed, after the hive
+cover had been removed, they fiercely attacked the band of black cloth
+as in the previous experiences; but the right white sleeve and the white
+suit were scarcely noticed. At one time a part of the black cloth was
+almost literally covered with furiously stinging bees, and the black
+veil was assailed by hundreds. The bees behaved in a similar manner when
+a second hive on the opposite side of the apiary was opened."
+
+"A white veil which had been procured for this purpose, was next
+substituted for the black veil. The result was most surprising, for,
+whereas in the previous experiments hundreds of bees had attacked the
+black veil, so few flew against the white veil as to cause me no
+inconvenience. Undoubtedly beekeepers will find it greatly to their
+advantage to wear white clothing when working among their colonies of
+bees and manipulating the frames of the hives."
+
+When a honey-bee stings, the tip of the abdomen, with the entire sting
+apparatus, is torn off and remains in the wound. Here the muscles
+continue to contract, for some minutes, forcing the barbs deeper and
+deeper into the skin, and forcing out additional poison from the
+reservoir.
+
+Treatment, therefore, first consists in removing the sting without
+squeezing out additional poison. This is accomplished by lifting and
+scraping it out with a knife-blade or the fingernail instead of grasping
+and pulling it out. Local application of alkalines, such as weak
+ammonia, are often recommended on the assumption that the poison is an
+acid to be neutralized on this manner, but these are of little or no
+avail. They should certainly not be rubbed in, as that would only
+accelerate the absorption of the poison. The use of cloths wrung out in
+hot water and applied as hot as can be borne, affords much relief in the
+case of severe stings. The application of wet clay, or of the end of a
+freshly cut potato is sometimes helpful.
+
+In extreme cases, where there is great susceptibility, or where there
+may have been many stings, a physician should be called. He may find
+strychnine injections or other treatment necessary, if general symptoms
+develop.
+
+[Illustration: 28. The poison apparatus of Formica. Wheeler, after
+Forel.]
+
+
+OTHER STINGING FORMS--Of the five thousand, or more, species of bees,
+most possess a sting and poison apparatus and some of the larger forms
+are capable of inflicting a much more painful sting than that of the
+common honey-bee. In fact, some, like the bumble bees, possess the
+advantage that they do not lose the sting from once using it, but are
+capable of driving it in repeatedly. In the tropics there are found many
+species of stingless bees but these are noted for their united efforts
+to drive away intruders by biting. Certain species possess a very
+irritating saliva which they inject into the wounds.
+
+The ants are not ordinarily regarded as worthy of consideration under
+the heading of "stinging insects" but as a matter of fact, most of them
+possess well developed stings and some of them, especially in the
+tropics, are very justly feared. Even those which lack the sting possess
+well-developed poison glands and the parts of the entire stinging
+apparatus, in so far as it is developed in the various species, may
+readily be homologized with those of the honey-bee.
+
+The ants lacking a sting are those of the subfamily CAMPONOTINÆ, which
+includes the largest of our local species. It is an interesting fact
+that some of these species possess the largest poison glands and
+reservoir (fig. 28) and it is found that when they attack an enemy they
+bring the tip of the abdomen forward and spray the poison in such a way
+that it is introduced into the wound made by the powerful mandibles.
+
+[Illustration: 29. A harmless, but much feared larva, the "tomato worm."
+Natural size. Photograph by M. V. S.]
+
+More feared than any of the other Hymenoptera are the hornets and wasps.
+Of these there are many species, some of which attain a large size and
+are truly formidable. Phisalix (1897), has made a study of the venom of
+the common hornet and finds that, like the poison of the honey-bee, it
+is neither an albuminoid nor an alkaloid. Its toxic properties are
+destroyed at 120° C. Phisalix also says that the venom is soluble in
+alcohol. If this be true, it differs in this respect from that of the
+bee. An interesting phase of the work of Phisalix is that several of her
+experiments go to show that the venom of hornets acts as a vaccine
+against that of vipers.
+
+
+NETTLING INSECTS
+
+So far, we have considered insects which possess poison glands connected
+with the mouth-parts or a special sting and which actively inject their
+poison into man. There remain to be considered those insects which
+possess poisonous hairs or body fluids which, under favorable
+circumstances, may act as poisons. To the first of these belong
+primarily the larvæ of certain Lepidoptera.
+
+
+LEPIDOPTERA
+
+[Illustration: 30. Another innocent but much maligned caterpillar, the
+larva of the Regal moth. Photograph by M. V. S.]
+
+When we consider the reputedly poisonous larvæ of moths and butterflies,
+one of the first things to impress us is that we cannot judge by mere
+appearance. Various species of Sphingid, or hawk-moth larvæ, bear at the
+end of the body a chitinous horn, which is often referred to as a
+"sting" and regarded as capable of inflicting dangerous wounds. It would
+seem unnecessary to refer to this absurd belief if it were not that each
+summer the newspapers contain supposed accounts of injury from the
+"tomato worm" (fig. 29) and others of this group. The grotesque, spiny
+larva (fig. 30) of one of our largest moths, _Citheronia regalis_ is
+much feared though perfectly harmless, and similar instances could be
+multiplied.
+
+[Illustration: 31. The flannel moth (Lagoa crispata). (_a_) Poisonous
+larva.]
+
+[Illustration: 31. (_b_) Adult. Enlarged. Photographs by M. V. S.]
+
+But if the larvæ are often misjudged on account of their ferocious
+appearance, the reverse may be true. A group of most innocent looking
+and attractive caterpillars is that of the flannel-moth larvæ, of which
+_Lagoa crispata_ may be taken as an example. Its larva (fig. 31) has a
+very short and thick body, which is fleshy and completely covered and
+hidden by long silken hairs of a tawny or brown color, giving a convex
+form to the upper side. Interspersed among these long hairs are
+numerous short spines connected with underlying hypodermal poison
+glands. These hairs are capable of producing a marked nettling effect
+when they come in contact with the skin. This species is found in our
+Atlantic and Southern States. Satisfactory studies of its poisonous
+hairs and their glands have not yet been made.
+
+[Illustration: 32 The poisonous saddle back caterpillar. Empretia
+(Sibine) stimulea. Photograph by M. V. S.]
+
+[Illustration: 33_a_. Io moth larvæ on willow. Photograph by M. V. S.]
+
+_Sibine stimulea (Empretia stimulea)_, or the saddle-back caterpillar
+(fig. 32), is another which possesses nettling hairs. This species
+belongs to the group of Eucleidæ, or slug caterpillars. It can be
+readily recognized by its flattened form, lateral, bristling spines and
+by the large green patch on the back resembling a saddle-cloth, while
+the saddle is represented by an oval, purplish-brown spot. The small
+spines are venomous and affect some persons very painfully. The larva
+feeds on the leaves of a large variety of forest trees and also on
+cherry, plum, and even corn leaves. It is to be found throughout the
+Eastern and Southern United States.
+
+[Illustration: 33_b_. Io moth. Full grown larva. Photograph by M. V. S.]
+
+[Illustration: 34. Io moth. Adult. Photograph by M. V. S.]
+
+_Automeris io_ is the best known of the nettling caterpillars. It is the
+larva of the Io moth, one of the Saturniidæ. The mature caterpillar,
+(fig. 33), which reaches a length of two and one-half inches, is of a
+beautiful pale green with sublateral stripes of cream and red color and
+a few black spines among the green ones. The green radiating spines give
+the body a mossy appearance. They are tipped with a slender chitinous
+hair whose tip is readily broken off in the skin and whose poisonous
+content causes great irritation. Some individuals are very susceptible
+to the poison, while others are able to handle the larvæ freely without
+any discomfort. The larvæ feed on a wide range of food plants. They are
+most commonly encountered on corn and on willow, because of the
+opportunities for coming in contact with them.
+
+[Illustration: 35. Larva of brown-tail moth. (Natural size). Photograph
+by M. V. S.]
+
+The larvæ of the brown-tail moth (_Euproctis chrysorrhœa_) (fig. 35
+and 36), where they occur in this country, are, on account of their
+great numbers, the most serious of all poisonous caterpillars. It is not
+necessary here, to go into details regarding the introduction of this
+species from Europe into the New England States. This is all available
+in the literature from the United States Bureau of Entomology and from
+that of the various states which are fighting the species. Suffice to
+say, there is every prospect that the pest will continue to spread
+throughout the Eastern United States and Canada and that wherever it
+goes it will prove a direct pest to man as well as to his plants.
+
+Very soon after the introduction of the species there occurred in the
+region where it had gained a foothold, a mysterious dermatitis of man.
+The breaking out which usually occurred on the neck or other exposed
+part of the body was always accompanied by an intense itching. It was
+soon found that this dermatitis was caused by certain short, barbed
+hairs of the brown-tail caterpillars and that not only the caterpillars
+but their cocoons and even the adult female moths might harbor these
+nettling hairs and thus give rise to the irritation. In many cases the
+hairs were wafted to clothing on the line and when this was worn it
+might cause the same trouble. Still worse, it was found that very
+serious internal injury was often caused by breathing or swallowing the
+poisonous hairs.
+
+[Illustration: 36. Browntail moths. One male and two females. Photograph
+by M. V. S.]
+
+The earlier studies seemed to indicate that the irritation was purely
+mechanical in origin, the result of the minute barbed hairs working into
+the skin in large numbers. Subsequently, however, Dr. Tyzzer (1907)
+demonstrated beyond question that the trouble was due to a poison
+contained in the hairs. In the first place, it is only the peculiar
+short barbed hairs which will produce the dermatitis when rubbed on the
+skin, although most of the other hairs are sharply barbed. Moreover, it
+was found that in various ways the nettling properties could be
+destroyed without modifying the structure of the hairs. This was
+accomplished by baking for one hour at 110° C, by warming to 60° C in
+distilled water, or by soaking in one per cent. or in one-tenth per
+cent. of potassium hydrate or sodium hydrate. The most significant part
+of his work was the demonstration of the fact that if the nettling
+hairs are mingled with blood, they immediately produce a change in the
+red corpuscles. These at once become coarsely crenated, and the roleaux
+are broken up in the vicinity of the hair (fig. 37_b_). The corpuscles
+decrease in size, the coarse crenations are transformed into slender
+spines which rapidly disappear, leaving the corpuscles in the form of
+spheres, the light refraction of which contrasts them sharply with the
+normal corpuscles. The reaction always begins at the basal sharp point
+of the hair. It could not be produced by purely mechanical means, such
+as the mingling of minute particles of glass wool, the barbed hairs of a
+tussock moth, or the other coarser hairs of the brown-tail, with the
+blood.
+
+[Illustration: 37. (_a_) Ordinary hairs and three poison hairs of
+subdorsal and lateral tubercles of the larva of the browntail moth.
+Drawing by Miss Kephart.]
+
+The question of the source of the poison has been studied in our
+laboratory by Miss Cornelia Kephart. She first confirmed Dr. Tyzzer's
+general results and then studied carefully fixed specimens of the larvæ
+to determine the distribution of the hairs and their relation to the
+underlying tissues.
+
+[Illustration: 37. (_b_) Effect of the poison on the blood corpuscles of
+man. After Tyzzer.]
+
+The poison hairs (fig. 37), are found on the subdorsal and lateral
+tubercles (fig. 38), in bunches of from three to twelve on the minute
+papillæ with which the tubercles are thickly covered. The underlying
+hypodermis is very greatly thickened, the cells being three or four
+times the length of the ordinary hypodermal cells and being closely
+crowded together. Instead of a pore canal through the cuticula for each
+individual hair, there is a single pore for each papillæ on a tubercle,
+all the hairs of the papilla being connected with the underlying cells
+through the same pore canal, (figs. 39 and 40).
+
+[Illustration: 38. Cross section of the larva of the browntail moth
+showing the tubercles bearing the poison hairs. Drawing by Miss
+Kephart.]
+
+The hypodermis of this region is of two distinct types of cells. First,
+there is a group of slender fusiform cells, one for each poison hair on
+the papilla, which are the trichogen, or hair-formative cells. They are
+crowded to one side and towards the basement membrane by a series of
+much larger, and more prominent cells (fig. 40), of which there is a
+single one for each papilla. These larger cells have a granular
+protoplasm with large nuclei and are obviously actively secreting. They
+are so characteristic in appearance as to leave no question but that
+they are the true poison glands.
+
+[Illustration: 39. Epithelium underlying poison hairs of the larva of
+the browntail moth. Drawing by Miss Kephart.]
+
+Poisonous larvæ of many other species have been reported from Europe and
+especially from the tropics but the above-mentioned species are the more
+important of those occurring in the United States and will serve as
+types. It should be noted in this connection that through some curious
+misunderstanding GÅ“ldi (1913) has featured the larva of _Orgyia
+leucostigma_, the white-marked tussock moth, as the most important of
+the poisonous caterpillars of this country. Though there are occasional
+reports of irritation from its hairs such cases are rare and there is no
+evidence that there is any poison present. Indeed, subcutaneous
+implantation of the hairs leads to no poisoning, but merely to temporary
+irritation.
+
+[Illustration: 40. Same as figure 39, on larger scale.]
+
+Occasionally, the hairs of certain species of caterpillars find
+lodgement in the conjunctiva, cornea, or iris of the eye of man and give
+rise to the condition known as _opthalmia nodosa_. The essential feature
+of this trouble is a nodular conjunctivitis which simulates tuberculosis
+of the conjunctiva and hence has been called _pseudo-tubercular_. It may
+be distinguished microscopically by the presence of the hairs.
+
+[Illustration: 41. (_a_) Nodular conjunctivitis in the eye of a child.
+De Schweinitz and Shumway.]
+
+Numerous cases of opthalmia nodosa are on record. Of those from this
+country, one of the most interesting is reported by de Schweinitz and
+Shumway (1904). It is that of a child of fifteen years whose eye had
+become inflamed owing to the presence of some foreign body. Downward and
+inward on the bulbar conjunctiva were a number of flattened,
+grayish-yellow nodules, between which was a marked congestion of the
+conjunctival and episcleral vessels (fig. 41_a_). Twenty-seven nodules
+could be differentiated, those directly in the center of the collection
+being somewhat confluent and assuming a crescentic and circular
+appearance. The nodules were excised and, on sectioning, were found to
+be composed of a layer of spindle cells and round cells, outside of
+which the tissue was condensed into a capsule. The interior consisted of
+epithelioid cells, between which was a considerable intercellular
+substance. Directly in the center of a certain number of nodules was
+found the section of a hair (fig. 41_b_). The evidence indicated that
+the injury had resulted from playing with caterpillars of one of the
+Arctiid moths, _Spilosoma virginica_. Other reported cases have been
+caused by the hairs of larvæ of _Lasiocampa rubi_, _L. pini_,
+_Porthetria dispar_, _Psilura monacha_ and _Cnethocampa processionea_.
+
+[Illustration: 41_b_. Section through one of the nodules showing the
+caterpillar hair. De Schweinitz and Shumway.]
+
+
+RELIEF FROM POISONING BY NETTLING LARVÆ--The irritation from nettling
+larvæ is often severe and, especially in regions where the brown-tail
+abounds, inquiries as to treatment arise. In general, it may be said
+that cooling lotions afford relief, and that scratching, with the
+possibilities of secondary infection, should be avoided, in so far as
+possible.
+
+Among the remedies usually at hand, weak solutions of ammonia, or a
+paste of ordinary baking soda are helpful. Castellani and Chalmers
+recommend cleaning away the hairs by bathing the region with an alkaline
+lotion, such as two per cent solution of bicarbonate of soda, and then
+applying an ointment of ichthyol (10%).
+
+In the brown-tail district, there are many proprietary remedies of which
+the best ones are essentially the following, as recommended by Kirkland
+(1907):
+
+    Carbolic acid    ½ drachm.
+    Zinc oxide       ½ oz.
+    Lime water       8 oz.
+
+Shake thoroughly and rub well into the affected parts.
+
+In some cases, and especially where there is danger of secondary
+infection, the use of a weak solution of creoline (one teaspoonful to a
+quart of water), is to be advised.
+
+
+VESCICATING INSECTS AND THOSE POSSESSING OTHER POISONS IN THEIR BLOOD
+PLASMA
+
+We have seen that certain forms, for example, the poisonous spiders, not
+only secrete a toxine in their poison glands, but that such a substance
+may be extracted from other parts of their body, or even their eggs.
+There are many insects which likewise possess a poisonous blood plasma.
+Such forms have been well designated by Taschenberg as _cryptotoxic_
+(κ�υπτοσ = hidden). We shall consider a few representative
+forms.
+
+[Illustration: 42_a_. Blister beetle.]
+
+[Illustration: 42_b_. An American blister beetle. Meloe angusticollis.
+Photograph by M. V. S.]
+
+
+THE BLISTER BEETLES--Foremost among the cryptotoxic insects are the
+_Meloidæ_ or "blister beetles," to which the well-known "Spanish fly"
+(fig. 42_a_), formerly very generally used in medical practice, belongs.
+The vescicating property is due to the presence in the blood plasma of a
+peculiar, volatile, crystalline substance known as _cantharidin_, which
+is especially abundant in the reproductive organs of the beetle.
+According to Kobert, the amount of this varies in different species from
+.4 or .5% to 2.57% of the dry weight of the beetle.
+
+While blister beetles have been especially used for external
+application, they are also at times used internally as a stimulant and a
+diuretic. The powder or extract was formerly much in vogue as an
+aphrodisiac, and formed the essential constituent of various philters,
+or "love powders". It is now known that its effects on the reproductive
+organs appear primarily after the kidneys have been affected to such an
+extent as to endanger life, and that many cases of fatal poison have
+been due to its ignorant use.
+
+There are many cases on record of poisoning and death due to internal
+use, and in some instances from merely external application. There are
+not rarely cases of poisoning of cattle from feeding on herbage bearing
+a large number of the beetles and authentic cases are known of human
+beings who have been poisoned by eating the flesh of such cattle. Kobert
+states that the beetles are not poisonous to birds but that the flesh of
+birds which have fed on them is poisonous to man, and that if the flesh
+of chickens or frogs which have fed on the cantharidin be fed to cats it
+causes in them the same symptoms as does the cantharidin.
+
+Treatment of cases of cantharidin poison is a matter for a skilled
+physician. Until he can be obtained, emetics should be administered and
+these should be followed by white of egg in water. Oils should be
+avoided, as they hasten the absorption of the poison.
+
+
+OTHER CRYPTOTOXIC INSECTS--Though the blister beetles are the best known
+of the insects with poisonous blood plasma, various others have been
+reported and we shall refer to a few of the best authenticated.
+
+One of the most famous is the Chrysomelid beetle, _Diamphidia simplex_,
+the body fluids of whose larvæ are used by certain South African bushmen
+as an arrow poison. Its action is due to the presence of a toxalbumin
+which exerts a hæmolytic action on the blood, and produces inflammation
+of the subcutaneous connective tissue and mucous membranes. Death
+results from general paralysis. Krause (1907) has surmised that the
+active principle may be a bacterial toxin arising from decomposition of
+the tissues of the larva, but he presents no support of this view and it
+is opposed by all the available evidence.
+
+In China, a bug, _Heuchis sanguinea_, belonging to the family Cicadidæ,
+is used like the Meloidæ, to produce blistering, and often causes
+poisoning. It has been assumed that its vescicating properties are due
+to cantharidin, but the presence of this substance has not been
+demonstrated.
+
+Certain Aphididæ contain a strongly irritating substance which produces,
+not merely on mucous membranes but on outer skin, a characteristic
+inflammation.
+
+It has been frequently reported that the larvæ of the European cabbage
+butterfly, _Pieris brassicæ_, accidentally eaten by cows, horses, ducks,
+and other domestic animals, cause severe colic, attempts to vomit,
+paralysis of the hind legs, salivation, and stomatitis. On _postmortem_
+there are to be found hæmorrhagic gastro-enteritis, splenitis, and
+nephritis. Kobert has recently investigated the subject and has found a
+poisonous substance in the blood of not only the larvæ but also the
+pupæ.
+
+
+FOOTNOTES:
+
+[A] This is diametrically opposed to the findings of Bordas (1905) in
+the case of the European _Latrodectus 13-guttatus_, whose glands are
+"much larger than those of other spiders." From a considerable
+comparative study, we should also unhesitatingly make this statement
+regarding the glands of our American species, _L. mactans_.
+
+[B] Dr. E. H. Coleman (Kellogg, 1915) has demonstrated its virulence by
+a series of experiments comparable with those of Kobert.
+
+[C] According to Stiles, the species occurring in the Northwest which is
+commonly identified as _D. venustus_ should be called _D. andersoni_
+(see footnote, chapter 12).
+
+[D] It should be remembered that in all the higher Hymenoptera the first
+abdominal segment is fused with the thorax and that what is apparently
+the sixth segment is, in reality, the seventh.
+
+
+
+
+CHAPTER III
+
+PARASITIC ARTHROPODA AFFECTING MAN
+
+
+The relation of insects to man as simple parasites has long been
+studied, and until very recent years the bulk of the literature of
+medical entomology referred to this phase of the subject. This is now
+completely overshadowed by the fact that so many of these parasitic
+forms are more than simple parasites, they are transmitters of other
+microscopic parasites which are pathogenic to man. Yet the importance of
+insects as parasites still remains and must be considered in a
+discussion of the relation of insects to the health of man. In taking up
+the subject we shall first consider some general features of the
+phenomenon of animal parasitism.
+
+Parasitism is an adaptation which has originated very often among living
+organisms and in widely separated groups. It would seem simple to define
+what is meant by a "parasite" but, in reality, the term is not easily
+limited. It is often stated that a parasite is "An organism which lives
+at the expense of another," but this definition is applicable to a
+predatory species or, in its broadest sense, to all organisms. For our
+purpose we may say with Braun: "A parasite is an organism which, for the
+purpose of obtaining food, takes up its abode, temporarily or
+permanently, on or within another living organism".
+
+Thus, parasitism is a phase of the broad biological phenomenon of
+_symbiosis_, or living together of organisms. It is distinguished from
+_mutualism_, or symbiosis in the narrow sense, by the fact that only one
+party to the arrangement obtains any advantage, while the other is to a
+greater or less extent injured.
+
+Of parasites we may distinguish on the basis of their location on or in
+the host, _ecto-parasites_, which live outside of the body; and
+_endo-parasites_, which live within the body. On account of their method
+of breathing the parasitic arthropods belong almost exclusively to the
+first of these groups.
+
+On the basis of relation to their host, we find _temporary parasites_,
+those which seek the host only occasionally, to obtain food; and the
+_stationary_ or _permanent_ parasites which, at least during certain
+stages, do not leave their host.
+
+_Facultative parasites_ are forms which are not normally parasitic, but
+which, when accidentally ingested, or otherwise brought into the body,
+are able to exist for a greater or less period of time in their unusual
+environment. These are generally called in the medical literature
+"pseudoparasites" but the term is an unfortunate one.
+
+We shall now take up the different groups of arthropods, discussing the
+more important of the parasitic forms attacking man. The systematic
+relationship of these forms, and key for determining important species
+will be found in Chapter XII.
+
+
+ACARINA OR MITES
+
+The ACARINA, or _mites_, form a fairly natural group of arachnids,
+characterized, in general, by a sac-like, unsegmented body which is
+generally fused with the cephalothorax. The mouth-parts have been united
+to form a beak or rostrum.
+
+The representatives of this group undergo a marked metamorphosis.
+Commonly, the larvæ on hatching from the egg, possess but three pairs of
+legs, and hence are called _hexapod larvæ_. After a molt, they transform
+into nymphs which, like the adult, have four pairs of legs and are
+called _octopod nymphs_. These after a period of growth, molt one or
+more times and, acquiring external sexual organs, become adult.
+
+Most of the mites are free-living, but there are many parasitic species
+and as these have originated in widely separated families, the Acarina
+form an especially favorable group for study of the origin of
+parasitism. Such a study has been made by Ewing (1911), who has reached
+the following conclusions:
+
+"We have strong evidence indicating that the parasitic habit has
+originated independently at least eleven times in the phylogeny of the
+Ararina. Among the zoophagous parasites, the parasitic habit has been
+developed from three different types of free-living Acarina: (a)
+predaceous forms, (b) scavengers, (c) forms living upon the juices of
+plants."
+
+Ewing also showed that among the living forms of Acarina we can trace
+out all the stages of advancing parasitism, semiparasitism, facultative
+parasitism, even to the fixed and permanent type, and finally to
+endoparasitism.
+
+Of the many parasitic forms, there are several species which are serious
+parasites of man and we shall consider the more important of these.
+Infestation by mites is technically known as _acariasis_.
+
+[Illustration: 43. Effect of the harvest mites on the skin of man.
+Photograph by J. C. Bradley.]
+
+
+The Trombidiidæ, or Harvest Mites
+
+In many parts of this country it is impossible for a visitor to go into
+the fields and, particularly, into berry patches and among tall weeds
+and grass in the summer or early fall without being affected by an
+intolerable itching, which is followed, later, by a breaking out of
+wheals, or papules, surrounded by a bright red or violaceous aureola,
+(fig. 43). It is often regarded as a urticaria or eczema, produced by
+change of climate, an error in diet, or some condition of general
+health.
+
+Sooner or later, the victim finds that it is due to none of these, but
+to the attacks of an almost microscopic red mite, usually called
+"jigger" or "chigger" in this country. As the term "chigger" is applied
+to one of the true fleas, _Dermatophilus penetrans_, of the tropics,
+these forms are more correctly known as "harvest mites." Natives of an
+infested region may be so immune or accustomed to its attacks as to be
+unaware of its presence, though such immunity is by no means possessed
+by all who have been long exposed to the annoyance.
+
+[Illustration: 44. Harvest mites. (Larvæ of Trombidium). After C. V.
+Riley.]
+
+The harvest mites, or chiggers, attacking man are larval forms,
+possessing three pairs of legs (fig. 44). Their systematic position was
+at first unknown and they were classed under a special genus _Leptus_, a
+name which is very commonly still retained in the medical literature. It
+is now known that they are the larval forms of various species of the
+genus _Trombidium_, a group of predaceous forms, the adults of which
+feed primarily on insects and their eggs. In this country the species
+best known are those to be found late in summer, as larvæ at the base of
+the wings of houseflies or grasshoppers.
+
+There is much uncertainty as to the species of the larvæ attacking man
+but it is clear that several are implicated. Bruyant has shown that in
+France the larvæ _Trombidium inapinatum_ and _Trombidium holosericeum_
+are those most frequently found. The habit of attacking man is abnormal
+and the larvæ die after entering the skin. Normally they are parasitic
+on various insects.
+
+Most recent writers agree that, on man, they do not bore into the skin,
+as is generally supposed, but enter a hair follicle or sebaceous gland
+and from the bottom of this, pierce the cutis with their elongate
+hypopharynx. According to Braun, there arises about the inserted
+hypopharynx a fibrous secretion--the so-called "beak" which is, in
+reality, a product of the host. Dr. J. C. Bradley, however, has made
+careful observations on their method of attack, and he assures us that
+the mite ordinarily remains for a long time feeding on the surface of
+the skin, where it produces the erythema above described. During this
+time it is not buried in the skin but is able to retreat rapidly into it
+through a hair follicle or sweat gland. The irritation from the mites
+ceases after a few days, but not infrequently the intolerable itching
+leads to so much scratching that secondary infection follows.
+
+Relief from the irritation may be afforded by taking a warm salt bath as
+soon as possible after exposure or by killing the mites by application
+of benzine, sulphur ointment or carbolized vaseline. When they are few
+in number, they can be picked out with a sterile needle.
+
+Much may be done in the way of warding off their attacks by wearing
+gaiters or close-woven stockings extending from ankle to the knee. Still
+more efficacious is the sprinkling of flowers of sulphur in the
+stockings and the underclothes from a little above the knee, down. The
+writers have known this to make it possible for persons who were
+especially susceptible to work with perfect comfort in badly infested
+regions. Powdered naphthalene is successfully used in the same way and
+as Chittenden (1906) points out, is a safeguard against various forms of
+man-infesting tropical insect pests.
+
+The question of the destruction of the mites in the field is sometimes
+an important one, and under some conditions, is feasible. Chittenden
+states that much can be accomplished by keeping the grass, weeds, and
+useless herbage mowed closely, so as to expose the mites to the sun. He
+believes that in some cases good may be done by dusting the grass and
+other plants, after cutting, with flowers of sulphur or by spraying with
+dilute kerosene emulsion in which sulphur has been mixed. More recently
+(1914) he calls attention to the value of cattle, and more especially
+sheep, in destroying the pests by tramping on them and by keeping the
+grass and herbage closely cropped.
+
+
+IXODOIDEA OR TICKS
+
+Until recently, the ticks attracted comparatively little attention from
+entomologists. Since their importance as carriers of disease has been
+established, interest in the group has been enormously stimulated and
+now they rank second only to the mosquitoes in the amount of detailed
+study that has been devoted to them.
+
+[Illustration: 45_a_. Argus persicus. Capitulum of male. After Nuttall
+and Warburton.]
+
+The ticks are the largest of the Acarina. They are characterized by the
+fact that the hypostome, or "tongue" (fig. 45) is large and file-like,
+roughened by sharp teeth. They possess a breathing pore on each side of
+the body, above the third or fourth coxæ (fig. 45_b_).
+
+[Illustration: 45_b_. Left spiracle of nymph of _Argas persicus_. After
+Nuttall and Warburton.]
+
+There are two distinct families of the IXODOIDEA, differing greatly in
+structure, life-history and habits. These are the ARGASIDÆ and the
+IXODIDÆ. We shall follow Nuttall (1908) in characterizing these two
+families and in pointing out their biological differences, and shall
+discuss briefly the more important species which attack man. The
+consideration of the ticks as carriers of disease will be reserved for a
+later chapter.
+
+
+Argasidæ
+
+In the ticks belonging to the family ARGASIDÆ, there is comparatively
+little sexual dimorphism, while this is very marked in the Ixodidæ. The
+capitulum, or so-called "head" is ventral, instead of terminal; the
+palpi are leg-like, with the segments subequal; the scutum, or dorsal
+shield, is absent; eyes, when present, are lateral, on supracoxal folds.
+The spiracles are very small; coxæ unarmed; tarsi without ventral
+spurs, and the pulvilli are absent or rudimentary.
+
+In habits and life history the Argasidæ present striking
+characteristics. In the first place, they are long-lived, a factor which
+counts for much in the maintenance of the species. They are intermittent
+feeders, being comparable with the bed-bug in this respect. There are
+two or more nymphal stages, and they may molt after attaining maturity.
+The female lays comparatively few eggs in several small batches.
+
+Nuttall (1911) concludes that "The Argasidæ represent the relatively
+primitive type of ticks because they are less constantly parasitic than
+are the Ixodidæ. Their nymphs and adults are rapid feeders and chiefly
+infest the habitat of their hosts. * * * Owing to the Argasidæ infesting
+the habitats of their hosts, their resistance to prolonged starvation
+and their rapid feeding habits, they do not need to bring forth a large
+progeny, because there is less loss of life in the various stages, as
+compared with the Ixodidæ, prior to their attaining maturity."
+
+[Illustration: 46. Argus persicus. Dorsal and ventral aspects. (×4).
+After Hassell.]
+
+Of the Argasidæ, we have in the United States, several species which
+have been reported as attacking man.
+
+_Argas persicus_, the famous "Miana bug" (fig. 46), is a very widely
+distributed species, being reported from Europe, Asia, Africa, and
+Australia. It is everywhere preeminently a parasite of fowls. According
+to Nuttall it is specifically identical with _Argas americanus_ Packard
+or _Argas miniatus_ Koch, which is commonly found on fowls in the United
+States, in the South and Southwest. Its habits are comparable to those
+of the bed-bug. It feeds intermittently, primarily at night, and instead
+of remaining on its host, it then retreats to cracks and crevices.
+Hunter and Hooker (1908) record that they have found the larva to remain
+attached for five or eight days before dropping. Unlike the Ixodidæ, the
+adults oviposit frequently.
+
+[Illustration: 47. Otiobius (Ornithodoros) megnini, head of nymph. After
+Stiles.]
+
+[Illustration: 48. Otiobius (Ornithodoros) megnini, male. (_a_) dorsal,
+(_b_) ventral aspect. After Nuttall and Warburton.]
+
+The most remarkable feature of the biology of this species is the great
+longevity, especially of the adult. Hunter and Hooker report keeping
+larvæ confined in summer in pill boxes immediately after hatching for
+about two months while under similar conditions those of the Ixodid,
+_Boophilus annulatus_ lived for but two or three days. Many writers have
+recorded keeping adults for long periods without food. We have kept
+specimens in a tin box for over a year and a half and at the end of that
+time a number were still alive. Laboulliene kept unfed adults for over
+three years. In view of the effectiveness of sulphur in warding off the
+attacks of Trombidiidæ, it is astonishing to find that Lounsbury has
+kept adults of _Argas persicus_ for three months in a box nearly filled
+with flowers of sulphur, with no apparent effect on them.
+
+We have already called attention to the occasional serious effects of
+the bites of this species. While such reports have been frequently
+discredited there can be no doubt that they have foundation in fact. The
+readiness with which this tick attacks man, and the extent to which old
+huts may be infested makes it especially troublesome.
+
+_Otiobius (Ornithodoros) megnini_, the "spinose ear-tick" (figs. 47,
+48), first described from Mexico, as occurring in the ears of horses, is
+a common species in our Southwestern States and is recorded by Banks as
+occurring as far north as Iowa.
+
+The species is remarkable for the great difference between the spiny
+nymph stage and the adult. The life history has been worked out by
+Hooker (1908). Seed ticks, having gained entrance to the ear, attach
+deeply down in the folds, engorge, and in about five days, molt; as
+nymphs with their spinose body they appear entirely unlike the larvæ. As
+nymphs they continue feeding sometimes for months. Finally the nymph
+leaves the host, molts to form the unspined adult, and without further
+feeding is fertilized and commences oviposition.
+
+The common name is due to the fact that in the young stage the ticks
+occur in the ear of their hosts, usually horses or cattle. Not
+uncommonly it has been reported as occurring in the ear of man and
+causing very severe pain. Stiles recommends that it be removed by
+pouring some bland oil into the ear.
+
+Banks (1908) reports three species of _Ornithodoros_--_O. turicata_,
+_coriaceus_ and _talaje_--as occurring in the United States. All of
+these attack man and are capable of inflicting very painful bites.
+
+
+Ixodidæ
+
+The ticks belonging to the family IXODIDÆ (figs. 49 and 50) exhibit a
+marked sexual dimorphism. The capitulum is anterior, terminal, instead
+of ventral as in the Argasidæ; the palpi are relatively rigid (except in
+the subfamily Ixodinæ), with rudimentary fourth segment; scutum present;
+eyes, when present, dorsal, on side of scutum. The spiracles are
+generally large, situated well behind the fourth coxæ; coxæ generally
+with spurs; pulvilli always present.
+
+In habits and life history the typical Ixodidæ differ greatly from the
+Argasidæ. They are relatively short-lived, though some recent work
+indicates that their longevity has been considerably under-estimated.
+Typically, they are permanent feeders, remaining on the host, or hosts,
+during the greater part of their life. They molt twice only, on leaving
+the larval and the nymphal stages. The adult female deposits a single,
+large batch of eggs. Contrasting the habits of the Ixodidæ to those of
+the Argasidæ, Nuttall (1911) emphasizes that the Ixodidæ are more highly
+specialized parasites. "The majority are parasitic on hosts having no
+fixed habitat and consequently all stages, as a rule, occur upon the
+host."
+
+[Illustration: 49. Ixodes ricinus; male, ventral aspect. After Braun and
+Luehe.]
+
+As mere parasites of man, apart from their power to transmit disease,
+the Ixodidæ are much less important than the Argasidæ. Many are reported
+as occasionally attacking man and of these the following native species
+may be mentioned.
+
+[Illustration: 50. Ixodes ricinus, var. scapularis, female. Capitulum
+and scutum; ventral aspect of capitulum; coxæ; tarsus 4; spiracle;
+genital and anal grooves. After Nuttall and Warburton.]
+
+_Ixodes ricinus_, the European castor bean tick (figs. 49, 50), is a
+species which has been often reported from this country but Banks (1908)
+has shown that, though it does occur, practically all of the records
+apply to _Ixodes scapularis_ or _Ixodes cookei_. In Europe, _Ixodes
+ricinus_ is very abundant and very commonly attacks man. At the point
+of penetration of the hypostome there is more or less inflammation but
+serious injury does not occur unless there have been introduced
+pathogenic bacteria or, unless the tick has been abruptly removed,
+leaving the capitulum in the wound. Under the latter circumstances,
+there may be an abscess formed about the foreign body and occasionally,
+serious results have followed. Under certain conditions the tick, in
+various stages, may penetrate under the skin and produce a tumor, within
+which it may survive for a considerable period of time.
+
+_Ixodes cookei_ is given by Banks as "common on mammals in the Eastern
+States as far west as the Rockies." It is said to affect man severely.
+
+_Amblyomma americanum_, (fig. 158c), the "lone star tick," is widely
+distributed in the United States. Its common name is derived from the
+single silvery spot on the scutum of the female. Hunter and Hooker
+regard this species as, next to _Boophilus annulatus_, the most
+important tick in the United States. Though more common on cattle, it
+appears to attack mammals generally, and "in portions of Louisiana and
+Texas it becomes a pest of considerable importance to moss gatherers and
+other persons who spend much time in the forests."
+
+_Amblyomma cajennense_, noted as a pest of man in central and tropical
+America, is reported from various places in the south and southwestern
+United States.
+
+_Dermacentor variabilis_ is a common dog tick of the eastern United
+States. It frequently attacks man, but the direct effects of its bite
+are negligible.
+
+The "Rocky Mountain spotted fever tick" (_Dermacentor andersoni_
+according to Stiles, _D. venustus_ according to Banks) is, from the
+viewpoint of its effects on man, the most important of the ticks of the
+United States. This is because, as has been clearly established, it
+transmits the so-called "spotted fever" of man in our northwestern
+states. This phase of the subject will be discussed later and it need
+merely be mentioned here, that this species has been reported as causing
+painful injuries by its bites. Dr. Stiles states that he has seen cases
+of rather severe lymphangitis and various sores and swellings developing
+from this cause. In one case, of an individual bitten near the elbow,
+the arm became very much swollen and the patient was confined in bed for
+several days. The so-called tick paralysis produced by this species is
+discussed in a preceding chapter.
+
+There are many other records of various species of ticks attacking man,
+but the above-mentioned will serve as typical and it is not necessary to
+enter into greater detail.
+
+
+TREATMENT OF TICK BITES--When a tick attaches to man the first thing to
+be done is to remove it without leaving the hypostome in the wound to
+fester and bring about secondary effects. This is best accomplished by
+applying to the tick's body some substance which will cause it to more
+readily loosen its hold. Gasoline or petroleum, oil or vaseline will
+serve. For removing the spinose ear-tick, Stiles recommends pouring some
+bland oil into the ear. Others have used effectively a pledget of cotton
+soaked in chloroform.
+
+In general, the treatment recommended by Wellman for the bites of
+_Ornithodoros moubata_ will prove helpful. It consists of prolonged
+bathing in very hot water, followed by the application of a strong
+solution of bicarbonate of soda, which is allowed to dry upon the skin.
+He states that this treatment is comforting. For severe itching he
+advises smearing the bites with vaseline, which is slightly impregnated
+with camphor or menthol. Medical aid should be sought when complications
+arise.
+
+The DERMANYSSIDÆ are Gamasid mites which differ from others of the group
+in that they are parasitic on vertebrates. None of the species normally
+attack man, but certain of them, especially the poultry mite, may be
+accidental annoyances.
+
+[Illustration: 51. Dermanyssus gallinæ, female. After Delafond.]
+
+_Dermanyssus gallinæ_ (fig. 51), the red mite of poultry, is an
+exceedingly common and widespread parasite of fowls. During the day it
+lives in cracks and crevices of poultry houses, under supports of
+roosts, and in litter of the food and nests, coming out at night to
+feed. They often attack people working in poultry houses or handling
+and plucking infested fowls. They may cause an intense pruritis, but
+they do not produce a true dermatosis, for they do not find conditions
+favorable for multiplication on the skin of man.
+
+
+Tarsonemidæ
+
+The representatives of the family TARSONEMIDÆ are minute mites, with the
+body divided into cephalothorax and abdomen. There is marked sexual
+dimorphism. The females possess stigmata at the anterior part of the
+body, at the base of the rostrum, and differ from all other mites in
+having on each side, a prominent clavate organ between the first and
+second legs. The larva, when it exists, is hexapodous and resembles the
+adult. A number of the species are true parasites on insects, while
+others attack plants. Several of them may be accidental parasites of
+man.
+
+[Illustration: 52. Pediculoides ventricosus, female. After Webster.]
+
+[Illustration: 53. Pediculoides ventricosus, gravid female. (×80).
+After Webster.]
+
+_Pediculoides ventricosus_ (fig. 52 and 53) is, of all the Tarsonemidæ
+reported, the one which has proved most troublesome to man. It is a
+predaceous species which attacks a large number of insects but which has
+most commonly been met with by man through its fondness for certain
+grain-infesting insects, notably the Angoumois grain moth, _Sitotroga
+cerealella_, and the wheat straw-worm, _Isosoma grande_. In recent years
+it has attracted much attention in the United States and its
+distribution and habits have been the object of detailed study by
+Webster (1901).
+
+[Illustration: 54. Pediculoides ventricosus, male. After Braun.]
+
+There is a very striking sexual dimorphism in this species. The
+non-gravid female is elongate, about 200µ by 70µ (fig. 52), with the
+abdomen slightly striated longitudinally. The gravid female (fig. 53)
+has the abdomen enormously swollen, so that it is from twenty to a
+hundred times greater than the rest of the body. The species is
+viviparous and the larvæ undergo their entire growth in the body of the
+mother. They emerge as sexually mature males and females which soon
+pair. The male (fig. 54) is much smaller, reaching a length of only 320µ
+but is relatively broad, 80µ, and angular. Its abdomen is very greatly
+reduced.
+
+As far back as 1850 it was noted as causing serious outbreaks of
+peculiar dermatitis among men handling infested grain. For some time the
+true source of the difficulty was unknown and it was even believed that
+the grain had been poisoned. Webster has shown that in this country (and
+probably in Europe as well) its attacks have been mistaken for those of
+the red bugs or "chiggers" (larval Trombiidæ). More recently a number of
+outbreaks of a mysterious "skin disease" were traced to the use of straw
+mattresses, which were found to be swarming with these almost
+microscopic forms which had turned their attentions to the occupants of
+the beds. Other cases cited were those of farmers running wheat through
+a fanning mill, and of thrashers engaged in feeding unthrashed grain
+into the cylinder of the machine.
+
+[Illustration: 55. Lesions produced by the attacks of Pediculoides
+ventricosus. After Webster.]
+
+The medical aspects of the question have been studied especially by
+Schamberg and Goldberger and from the latter's summary (1910) we derive
+the following data. Within twelve to sixteen hours after exposure,
+itching appears and in severe cases, especially where exposure is
+continued night after night by sleeping on an infested bed, the itching
+may become almost intolerable. Simultaneously, there appears an eruption
+which characteristically consists of wheals surrounded by a vesicle
+(fig. 55). The vesicle as a rule does not exceed a pin head in size but
+may become as large as a pea. Its contents rapidly become turbid and in
+a few hours it is converted into a pustule. The eruption is most
+abundant on the trunk, slight on the face and extremities and almost
+absent on the feet and hands. In severe cases there may be
+constitutional disturbances marked, at the outset, by chilliness,
+nausea, and vomiting, followed for a few days by a slight elevation of
+temperature, with the appearance of albumin in the urine. In some cases
+the eruption may simulate that of chicken-pox or small-pox.
+
+Treatment for the purpose of killing the mites is hardly necessary as
+they attach feebly to the surface and are readily brushed off by
+friction of the clothes. "Antipruritic treatment is always called for;
+warm, mildly alkaline baths or some soothing ointment, such as zinc
+oxide will be found to fulfil this indication." Of course, reinfestation
+must be guarded against, by discarding, or thoroughly fumigating
+infested mattresses, or by avoiding other sources. Goldberger suggests
+that farm laborers who must work with infested wheat or straw might
+protect themselves by anointing the body freely with some bland oil or
+grease, followed by a change of clothes and bath as soon as their work
+is done. We are not aware of any experiments to determine the effect of
+flowers of sulphur, but their efficiency in the case of "red bugs"
+suggests that they are worth a trial against _Pediculoides_.
+
+Various species of TYROGLYPHIDÆ (fig. 150_f_) may abound on dried fruits
+and other products and attacking persons handling them, may cause a
+severe dermatitis, comparable to that described above for _Pediculoides
+ventricosus_. Many instances of their occurrence as such temporary
+ectoparasites are on record. Thus, workers who handle vanilla pods are
+subject to a severe dermatitis, known as vanillism, which is due to the
+attacks of _Tyroglyphus siro_, or a closely related species. The
+so-called "grocer's itch" is similarly caused by mites infesting various
+products. Castellani has shown that in Ceylon, workers employed in the
+copra mills, where dried cocoanut is ground up for export, are much
+annoyed by mites, which produce the so-called "copra itch." The skin of
+the hands, arms and legs, and sometimes of the whole body, except the
+face, is covered by fairly numerous, very pruriginous papules, often
+covered by small, bloody crusts due to scratching. The condition is
+readily mistaken for scabies. It is due to the attacks of _Tyroglyphus
+longior castellanii_ which occur in enormous numbers in some samples of
+the copra.
+
+
+Sarcoptidæ
+
+The SARCOPTIDÆ are minute whitish mites, semi-globular in shape, with a
+delicate transversely striated cuticula. They lack eyes and tracheæ. The
+mouth-parts are fused at the base to form a cone which is usually
+designated as the head. The legs are short and stout, and composed of
+five segments. The tarsi may or may not possess a claw and may terminate
+in a pedunculated sucker, or simple long bristle, or both. The presence
+or absence of these structures and their distribution are much used in
+classification. The mites live on or under the skin of mammals and
+birds, where they produce the disease known as scabies, mange, or itch.
+Several species of the Sarcoptidæ attack man but the most important of
+these, and the one pre-eminent as the "itch mite" is _Sarcoptes
+scabiei_.
+
+The female of _Sarcoptes scabiei_, of man, is oval and yellowish white;
+the male more rounded and of a somewhat reddish tinge, and much smaller.
+The body is marked by transverse striæ which are partly interrupted on
+the back. There are transverse rows of scales, or pointed spines, and
+scattered bristles on the dorsum.
+
+[Illustration: 56_a_. Sarcoptes scabiei, male. (×100). After
+Fürstenberg.]
+
+The male (fig. 56) which is from 200-240µ in length, and 150-200µ in
+breadth, possesses pedunculated suckers on each pair of legs except the
+third, which bears, instead, a long bristle. The female (fig. 56)
+300-450µ in length and 250-350µ in breadth, has the pedunculated suckers
+on the first and second pairs of legs, only, the third and fourth
+terminating in bristles.
+
+[Illustration: 56_b_. Sarcoptes scabiei, female. (×100.) After
+Fürstenberg.]
+
+The mite lives in irregular galleries from a few millimeters to several
+centimeters in length, which it excavates in the epidermis (fig. 57). It
+works especially where the skin is thin, such as between the fingers, in
+the bend of the elbows and knees, and in the groin, but it is by no
+means restricted to these localities. The female, alone, tunnels into
+the skin; the males remain under the superficial epidermal scales, and
+seldom are found, as they die soon after mating.
+
+As she burrows into the skin the female deposits her eggs, which measure
+about 150 × 100µ. Fürstenberg says that each deposits an average of
+twenty-two to twenty-four eggs, though Gudden reports a single burrow as
+containing fifty-one. From these there develop after about seven days,
+the hexapod larvæ. These molt on the sixteenth day to form an octopod
+nymph, which molts again the twenty-first day. At the end of the fourth
+week the nymphs molt to form the sexually mature males and the so-called
+pubescent females. These pair, the males die, and the females again cast
+their skin, and become the oviparous females. Thus the life cycle is
+completed in about twenty-eight days.
+
+The external temperature exercises a great influence on the development
+of the mites and thus, during the winter, the areas of infestation not
+only do not spread, but they become restricted. As soon as the
+temperature rises, the mites increase and the infestation becomes much
+more extensive.
+
+[Illustration: 57. Sarcoptes scabiei. Diagrammatic representation of the
+course in the skin of man.]
+
+In considering the possible sources of infestation, and the chances of
+reinfestation after treatment, the question of the ability of the mite
+to live apart from its host is a very important one. Unfortunately there
+are few reliable data on this subject. Gerlach found that, exposed in
+the dry, warm air of a room they became very inactive within twenty-four
+hours, that after two days they showed only slight movement, and that
+after three or four days they could not be revived by moisture and
+warming. The important fact was brought out that in moist air, in folded
+soiled underwear, they survived as long as ten days. Bourguignon found
+that under the most favorable conditions the mites of _Sarcoptes scabiei
+equi_ would live for sixteen days.
+
+The disease designated the "itch" or "scabies," in man has been known
+from time immemorial, but until within less than a hundred years it was
+almost universally attributed to malnutrition, errors of diet, or "bad
+blood." This was in spite of the fact that the mite was known to Mouffet
+and that Bonomo had figured both the adult and the egg and had declared
+the mite the sole cause of the disease. In 1834 the Corsican medical
+student, Francis Renucci, demonstrated the mite before a clinic in Saint
+Louis Hospital in Paris and soon thereafter there followed detailed
+studies of the life history of the various itch mites of man and
+animals.
+
+[Illustration: 58. Scabies on the hand. From portfolio of Dermochromes
+by permission of Rebman & Co., of New York. Publishers.]
+
+The disease is a cosmopolitan one, being exceedingly abundant in some
+localities. Its spread is much favored where large numbers of people are
+crowded together under insanitary conditions and hence it increases
+greatly during wars and is widely disseminated and abundant immediately
+afterwards. Though more commonly to be met with among the lower classes,
+it not infrequently appears among those of the most cleanly, careful
+habits, and it is such cases that are most liable to wrong diagnosis by
+the physician.
+
+Infection occurs solely through the passage, direct or indirect, of the
+young fertilized females to the skin of a healthy individual. The adult,
+oviparous females do not quit their galleries and hence do not serve to
+spread the disease. The young females move about more or less at night
+and thus the principal source of infestation is through sleeping in the
+same bed with an infested person, or indirectly through bedclothes, or
+even towels or clothing. Diurnal infestation through contact or clothing
+is exceptional. Many cases are known of the disease being contracted
+from animals suffering from scabies, or mange.
+
+When a person is exposed to infestation, the trouble manifests itself
+after eight or ten days, though there usually elapses a period of twenty
+to thirty days before there is a suspicion of anything serious. The
+first symptom is an intense itching which increases when the patient is
+in bed. When the point of irritation is examined the galleries may
+usually be seen as characteristic sinuous lines, at first whitish in
+color but soon becoming blackish because of the contained eggs and
+excrement. The galleries, which may not be very distinct in some cases,
+may measure as much as four centimeters in length. Little vesicles, of
+the size of a pin head are produced by the secretions of the feeding
+mite; they are firm, and projecting, and contain a limpid fluid. Figures
+58 and 59 show the typical appearance of scabies on the hands, while
+figure 60 shows a severe general infestation. The intolerable itching
+induces scratching and through this various complications may arise. The
+lesions are not normally found on the face and scalp, and are rare on
+the back.
+
+[Illustration: 59. Scabies on the hand. After Duhring.]
+
+[Illustration: 60. Generalized infection of Scabies. After Morrow.]
+
+Formerly, scabies was considered a very serious disease, for its cause
+and method of treatment were unknown, and potentially it may continue
+indefinitely. Generation after generation of the mites may develop and
+finally their number become so great that the general health of the
+individual is seriously affected. Now that the true cause of the disease
+is known, it is easily controlled.
+
+Treatment usually consists in softening the skin by friction with soap
+and warm water, followed by a warm bath, and then applying some
+substance to kill the mites. Stiles gives the following directions,
+modified from Bourguignon's, as "a rather radical guide, to be modified
+according to facilities and according to the delicacy of the skin or
+condition of the patient":
+
+1. The patient, stripped naked, is energetically rubbed all over (except
+the head) for twenty minutes, with green soap and warm water. 2. He is
+then placed in a warm bath for thirty minutes, during which time the
+rubbing is continued. 3. The parasiticide is next rubbed in for twenty
+minutes and is allowed to remain on the body for four or five hours; in
+the meantime the patient's clothes are sterilized, to kill the eggs or
+mites attached to them. 4. A final bath is taken to remove the
+parasiticide.
+
+The parasiticide usually relied on is the officinal sulphur ointment of
+the United States pharmacopœia. When infestation is severe it is
+necessary to repeat treatment after three or four days in order to kill
+mites which have hatched from the eggs.
+
+The above treatment is too severe for some individuals and may, of
+itself, produce a troublesome dermatitis. We have seen cases where the
+treatment was persisted in and aggravated the condition because it was
+supposed to be due to the parasite. For delicate-skinned patients the
+use of balsam of Peru is very satisfactory, and usually causes no
+irritation whatever. Of course, sources of reinfection should be
+carefully guarded against.
+
+_Sarcoptes scabiei crustosæ_, which is a distinct variety, if not
+species, of the human itch mite, is the cause of so-called Norwegian
+itch. This disease is very contagious, and is much more resistant than
+the ordinary scabies. Unlike the latter, it may occur on the face and
+scalp.
+
+_Sarcoptes scabiei_ not only attacks man but also occurs on a large
+number of mammals. Many species, based on choice of host, and minute
+differences in size and secondary characters, have been established, but
+most students of the subject relegate these to varietal rank. Many of
+them readily attack man, but they have become sufficiently adapted to
+their normal host so that they are usually less persistent on man.
+
+_Notoedres cati_ (usually known as _Sarcoptes minor_) is a species of
+itch mites which produce an often fatal disease of cats. The body is
+rounded and it is considerably smaller than _Sarcoptes scabiei_, the
+female (fig. 61) measuring 215-230µ long and 165-175µ wide; the males
+145-150µ by 120-125µ. The most important character separating
+_Notoedres_ from _Sarcoptes_ is the position of the anus, which is
+dorsal instead of terminal. The mite readily transfers to man but does
+not persist, the infestation usually disappearing spontaneously in about
+two weeks. Infested cats are very difficult to cure, unless treatment is
+begun at the very inception of the outbreak, and under ordinary
+circumstances it is better to kill them promptly, to avoid spread of the
+disease to children and others who may be exposed.
+
+[Illustration: 61. Notoedres cati, male and female. After Railliet.]
+
+
+Demodecidæ
+
+The DEMODECIDÆ are small, elongate, vermiform mites which live in the
+hair follicles of mammals. The family characteristics will be brought
+out in the discussion of the species infesting man, _Demodex
+folliculorum_.
+
+[Illustration: 62. Demodex folliculorum. (×200) After Blanchard.]
+
+_Demodex folliculorum_ (fig. 62) is to be found very commonly in the
+hair follicles and sebaceous glands of man. It is vermiform in
+appearance, and with the elongate abdomen transversely striated so as to
+give it the appearance of segmentation. The female is 380-400µ long by
+45µ; the male 300µ by 40µ. The three-jointed legs, eight in number, are
+reduced to mere stubs in the adult. The larval form is hexopod. These
+mites thus show in their form a striking adaptation to their
+environment. In the sebaceous glands and hair follicles they lie with
+their heads down (fig. 63). Usually there are only a few in a gland, but
+Gruby has counted as many as two hundred.
+
+[Illustration: 63. Demodex folliculorum. Section through skin showing
+the mites in situ. Magnification of Nos. 1, 2, 6 and 7, ×150; Nos, 3,
+4, 5, ×450. After Megnin.]
+
+The frequency with which they occur in man is surprising. According to
+European statistics they are found in 50 per cent to 60 per cent or even
+more. Gruby found them in forty out of sixty persons examined. These
+figures are very commonly quoted, but reliable data for the United
+States seem to be lacking. Our studies indicate that it is very much
+less common in this country than is generally assumed.
+
+The Demodex in man does not, as a rule, cause the slightest
+inconvenience to its host. It is often stated that they give rise to
+comedons or "black-heads" but there is no clear evidence that they are
+ever implicated. Certain it is that they are not the usual cause. A
+variety of the same, or a very closely related species of _Demodex_, on
+the dog gives rise to the very resistant and often fatal follicular
+mange.
+
+
+HEXAPODA OR TRUE INSECTS
+
+The HEXAPODA, or true insects, are characterized by the fact that the
+adult possesses three pairs of legs. The body is distinctly segmented
+and is divided into head, thorax, and abdomen.
+
+The mouth-parts in a generalized form, consist of an upper lip, or
+_labrum_, which is a part of the head capsule, and a central unpaired
+_hypopharynx_, two _mandibles_, two _maxillæ_ and a lower lip, or
+_labium_, made up of the fused pair of second maxillæ. These parts may
+be greatly modified, dependent upon whether they are used for biting,
+sucking, piercing and sucking, or a combination of biting and sucking.
+
+Roughly speaking, insects may be grouped into those which undergo
+_complete metamorphosis_ and those which have _incomplete
+metamorphosis_. They are said to undergo complete metamorphosis when the
+young form, as it leaves the egg, bears no resemblance to the adult. For
+example, the maggot changes to a quiescent pupa and from this emerges
+the winged active fly. They undergo incomplete metamorphosis, when the
+young insect, as it leaves the egg, resembles the adult to a greater or
+less extent, and after undergoing a certain number of molts becomes
+sexually mature.
+
+Representatives of several orders have been reported as accidental or
+faculative parasites of man, but the true parasites are restricted to
+four orders. These are the Siphunculata; the Hemiptera, the Diptera and
+the Siphonaptera.
+
+
+SIPHUNCULATA
+
+The order SIPHUNCULATA was established by Meinert to include the true
+sucking lice. These are small wingless insects, with reduced
+mouth-parts, adapted for sucking; thorax apparently a single piece due
+to indistinct separation of its three segments: the compound eyes
+reduced to a single ommatidium on each side. The short, powerful legs
+are terminated by a single long claw. Metamorphosis incomplete.
+
+There has been a great deal of discussion regarding the structure of the
+mouth-parts, and the relationships of the sucking lice, and the
+questions cannot yet be regarded as settled. The conflicting views are
+well represented by Cholodkovsky (1904 and 1905) and by Enderlein
+(1904).
+
+[Illustration: 64. Pediculus showing the blind sac (_b_) containing the
+mouth parts (_a_) beneath the alimentary canal (_p_). After Pawlowsky.]
+
+Following Graber, it is generally stated that the mouth-parts consist of
+a short tube furnished with hooks in front, which constitutes the lower
+lip, and that within this is a delicate sucking tube derived from the
+fusion of the labrum and the mandibles. Opposed to this, Cholodkovsky
+and, more recently, Pawlowsky, (1906), have shown that the piercing
+apparatus lies in a blind sac under the pharynx and opening into the
+mouth cavity (fig. 64). It does not form a true tube but a furrow with
+its open surface uppermost. Eysell has shown that, in addition, there is
+a pair of chitinous rods which he regards as the homologues of the
+maxillæ.
+
+When the louse feeds, it everts the anterior part of the mouth cavity,
+with its circle of hooks. The latter serve for anchoring the bug, and
+the piercing apparatus is then pushed out.
+
+[Illustration: 65. Pediculus humanus, ventral aspect of male. (×10)]
+
+Most writers have classed the sucking lice as a sub-order of the
+Hemiptera, but the more recent anatomical and developmental studies
+render this grouping untenable. An important fact, bearing on the
+question, is that, as shown by Gross, (1905), the structure of the
+ovaries is radically different from that of the Hemiptera.
+
+Lice infestation and its effects are known medically as _pediculosis_.
+Though their continued presence is the result of the grossest neglect
+and filthiness, the original infestation may be innocently obtained and
+by people of the most careful habits.
+
+Three species commonly attack man. Strangely enough, there are very few
+accurate data regarding their life history.
+
+_Pediculus humanus_ (fig. 65), the head louse, is the most widely
+distributed. It is usually referred to in medical literature as
+_Pediculus capitis_, but the Linnean specific name has priority. In
+color it is of a pale gray, blackish on the margins. It is claimed by
+some authors that the color varies according to the color of the skin of
+the host. The abdomen is composed of seven distinct segments, bearing
+spiracles laterally. There is considerable variation in size. The males
+average 1.8 mm. and the females 2.7 mm. in length.
+
+The eggs, fifty to sixty in number, stick firmly to the hairs of the
+host and are known as nits. They are large and conspicuous, especially
+on dark hair and are provided with an operculum, or cap, at the free
+end, where the nymphs emerge. They hatch in about six days and about the
+eighteenth day the young lice are sexually mature.
+
+[Illustration: 66. Pediculosis of the head. The illustration shows the
+characteristic indications of the presence of lice, viz: the occipital
+eczema gluing the hairs together, the swollen cervical glands, and the
+porrigo, or eruption of contagious pustules upon the neck. After Fox.]
+
+The head lice live by preference on the scalp of their host but
+occasionally they are found on the eyelashes and beard, or in the pubic
+region. They may also occur elsewhere on the body. The penetration of
+the rostrum into the skin and the discharge of an irritating saliva
+produce a severe itching, accompanied by the formation of an eczema-like
+eruption (fig. 66). When the infestation is severe, the discharge from
+the pustules mats down the hair, and scabs are formed, under which the
+insects swarm. "If allowed to run, a regular carapace may form, called
+_trichoma_, and the head exudes a fœtid odor. Various low plants may
+grow in the trichoma, the whole being known as _plica
+palonica_."--Stiles.
+
+Sources of infestation are various. School children may obtain the lice
+from seatmates, by wearing the hats or caps of infested mates, or by the
+use, in common, of brushes and combs. They may be obtained from infested
+beds or sleeper berths. Stiles reports an instance in which a large
+number of girls in a fashionable boarding school developed lousiness a
+short time after traveling in a sleeping car.
+
+Treatment is simple, for the parasites may readily be controlled by
+cleanliness and washing the head with a two per cent solution of
+carbolic acid or even kerosene. The latter is better used mixed with
+equal parts of olive oil, to avoid irritation. The treatment should be
+applied at night and followed the next morning by a shampoo with soap
+and warm water. It is necessary to repeat the operation in a few days.
+Xylol, used pure, or with the addition of five per cent of vaseline, is
+also very efficacious. Of course, the patient must be cautioned to stay
+away from a lighted lamp or fire while using either the kerosene or
+xylol. While these treatments will kill the eggs or nits, they will not
+remove them from the hairs. Pusey recommends repeated washings with
+vinegar or 25 per cent of acetic acid in water, for the purpose of
+loosening and removing the nits.
+
+Treatment of severe infestations in females is often troublesome on
+account of long hair. For such cases the following method recommended by
+Whitfield (1912) is especially applicable:
+
+The patient is laid on her back on the bed with her head over the edge,
+and beneath the head is placed a basin on a chair so that the hair lies
+in the basin. A solution of 1 in 40 carbolic acid is then poured over
+the hair into the basin and sluiced backwards and forwards until the
+whole of the hair is thoroughly soaked with it. It is especially
+necessary that care should be taken to secure thorough saturation of the
+hair over the ears and at the nape of the neck, since these parts are
+not only the sites of predilection of the parasites but they are apt to
+escape the solution. This sluicing is carried out for ten minutes by the
+clock. At the end of ten minutes the hair is lifted from the basin and
+allowed to drain, but is not dried or even thoroughly wrung out. The
+whole head is then swathed with a thick towel or better, a large piece
+of common house flannel, which is fastened up to form a sort of turban,
+and is allowed to remain thus for an hour. It can then be washed or
+simply allowed to dry, as the carbolic quickly disperses. At the end of
+this period every pediculus and what is better, every ovum is dead and
+no relapse will occur unless there is exposure to fresh contagion.
+Whitfield states that there seem to be no disadvantages in this method,
+which he has used for years. He has never seen carboluria result from
+it, but would advise first cutting the hair of children under five years
+of age.
+
+_Pediculus corporis_ (= _P. vestimenti_) the body louse, is larger than
+the preceding species, the female measuring 3.3 mm., and the male 3 mm.
+in length. The color is a dirty white, or grayish. _P. corporis_ has
+been regarded by some authorities as merely a variety of _P. humanus_
+but Piaget maintains there are good characters separating the two
+species.
+
+The body louse lives in the folds and seams of the clothing of its host,
+passing to the skin only when it wishes to feed. Brumpt states that he
+has found enormous numbers of them in the collars of glass-ware or
+grains worn by certain naked tribes in Africa.
+
+Exact data regarding the life-history of this species have been
+supplied, in part, by the work of Warburton (1910), cited by Nuttall. He
+found that _Pediculus corporis_ lives longer than _P. humanus_ under
+adverse conditions. This is doubtless due to its living habitually on
+the clothing, whereas _humanus_ lives upon the head, where it has more
+frequent opportunities of feeding. He reared a single female upon his
+own person, keeping the louse enclosed in a cotton-plugged tube with a
+particle of cloth to which it could cling. The tube was kept next to his
+body, thus simulating the natural conditions of warmth and moisture
+under which the lice thrive. The specimen was fed twice daily, while it
+clung to the cloth upon which it rested. Under these conditions she
+lived for one month. Copulation commenced five days after the female had
+hatched and was repeated a number of times, sexual union lasting for
+hours. The female laid one hundred and twenty-four eggs within
+twenty-five days.
+
+The eggs hatched after eight days, under favorable conditions, such as
+those under which the female was kept. They did not hatch in the cold.
+Eggs kept near the person during the day and hung in clothing by the
+bedside at night, during the winter, in a cold room, did not hatch until
+the thirty-fifth day. When the nymphs emerge from the eggs, they feed at
+once, if given a chance to do so. They are prone to scatter about the
+person and abandon the fragment of cloth to which the adult clings.
+
+The adult stage is reached on the eleventh day, after three molts, about
+four days apart. Adults enter into copulation about the fifth day and as
+the eggs require eight days for development, the total cycle, under
+favorable conditions, is about twenty-four days. Warburton's data differ
+considerably from those commonly quoted and serve to emphasize the
+necessity for detailed studies of some of the commonest of parasitic
+insects.
+
+Body lice are voracious feeders, producing by their bites and the
+irritating saliva which they inject, rosy elevations and papules which
+become covered with a brownish crust. The intense itching provokes
+scratching, and characteristic white scars (fig. 67) surrounded by
+brownish pigment (fig. 68) are formed. The skin may become thickened and
+take on a bronze tinge. This melanoderma is especially marked in the
+region between the shoulders but it may become generalized, a prominent
+characteristic of "vagabond's disease." According to Dubre and Beille,
+this melanoderma is due to a toxic substance secreted by the lice, which
+indirectly provokes the formation of pigment.
+
+[Illustration: 67. Pediculosis in man caused by the body louse. After
+Morrow.]
+
+Control measures, in the case of the body louse, consist in boiling or
+steaming the clothes or in some cases, sterilizing by dry heat. The
+dermatitis may be relieved by the use of zinc-oxide ointment, to which
+Pusey recommends that there be added, on account of their parasiticidal
+properties, sulphur and balsam of Peru, equal parts, 15 to 30 grains to
+the ounce.
+
+_Phthirius pubis_ (= _P. inguinalis_), the pubic louse, or so-called
+"crab louse," differs greatly from the preceding in appearance. It is
+characterized by its relatively short head which fits into a broad
+depression in the thorax. The latter is broad and flat and merges into
+the abdomen. The first pair of legs is slender and terminated by a
+straight claw. The second and third pairs of legs are thicker and are
+provided with powerful claws fitted for clinging to hairs. The females
+(fig. 69) measure 1.5 to 2 mm. in length by 1.5 mm. in breadth. The male
+averages a little over half as large. The eggs, or nits, are fixed at
+the base of the hairs. Only a few, ten to fifteen are deposited by a
+single female, and they hatch in about a week's time. The young lice
+mature in two weeks.
+
+The pubic louse usually infests the hairs of the pubis and the perineal
+region. It may pass to the arm pits or even to the beard or moustache.
+Rarely, it occurs on the eyelids, and it has even been found, in a very
+few instances, occurring in all stages, on the scalp. Infestation may be
+contracted from beds or even from badly infested persons in a crowd. We
+have seen several cases which undoubtedly were due to the use of public
+water closets. It produces papular eruption and an intense pruritis.
+When abundant, there occurs a grayish discoloration of the skin which
+Duguet has shown is due to a poisonous saliva injected by the louse, as
+is the melanoderma caused by the body louse.
+
+[Illustration: 68. Melanoderma caused by the body louse. From Portfolio
+of Dermochromes, by permission of Rebman & Co., New York, Publishers.]
+
+The pubic louse may be exterminated by the measures recommended for the
+head louse, or by the use of officinal mercurial ointment.
+
+[Illustration: 69. Phthirius pubis. Ventral aspect of female. (×12).]
+
+
+HEMIPTERA
+
+Several species of HEMIPTERA-HETEROPTERA are habitual parasites of man,
+and others occur as occasional or accidental parasites. Of all these,
+the most important and widespread are the bed-bugs, belonging to the
+genus _Cimex_ (= _Acanthia_).
+
+
+THE BED-BUGS--The bed-bugs are characterized by a much flattened oval
+body, with the short, broad head unconstricted behind, and fitting into
+the strongly excavated anterior margin of the thorax. The compound eyes
+are prominent, simple eyes lacking. Antennæ four-jointed, the first
+segment short, the second long and thick, and the third and fourth
+slender. The tarsi are short and three segmented.
+
+It is often assumed in the literature of the subject that there is but a
+single species of _Cimex_ attacking man, but several such species are to
+be recognized. These are distinguishable by the characters given in
+Chapter XII. We shall consider especially _Cimex lectularius_, the most
+common and widespread species.
+
+_Cimex lectularius_ (= _Acanthia lectularia_, _Clinocoris
+lectularius_), is one of the most cosmopolitan of human parasites but,
+like the lice, it has been comparatively little studied until recent
+years, when the possibility that it may be concerned with the
+transmission of various diseases has awakened interest in the details of
+its life-history and habits.
+
+[Illustration: 70. Cimex lectularius adult and eggs. Photograph by M. V.
+S.]
+
+The adult insect (fig. 70) is 4-5 mm. long by 3 mm. broad, reddish brown
+in color, with the beak and body appendages lighter in color. The short,
+broad and somewhat rectangular head has no neck-like constriction but
+fits into the broadly semilunar prothorax. The four segmented labium or
+proboscis encloses the lancet-like maxillæ and mandibles. The distal of
+the four antennal segments is slightly club-shaped. The prothorax is
+characteristic of the species, being deeply incised anteriorly and with
+its thin lateral margins somewhat turned up. The mesothorax is
+triangular, with the apex posteriorly, and bears the greatly atrophied
+first pair of wings. There is no trace of the metathoracic pair. The
+greatly flattened abdomen has eight visible segments, though in reality
+the first is greatly reduced and has been disregarded by most writers.
+The body is densely covered with short bristles and hairs, the former
+being peculiarly saber-shaped structures sharply toothed at the apex and
+along the convex side (fig. 159_b_).
+
+The peculiar disagreeable odor of the adult bed-bug is due to the
+secretion of the stink glands which lie on the inner surface of the
+mesosternum and open by a pair of orifices in front of the metacoxæ,
+near the middle line. In the nymphs, the thoracic glands are not
+developed but in the abdomen there are to be found three unpaired dorsal
+stink glands, which persist until the fifth molt, when they become
+atrophied and replaced by the thoracic glands. The nymphal glands occupy
+the median dorsal portion of the abdomen, opening by paired pores at the
+anterior margin of the fourth, fifth and sixth segments. The secretion
+is a clear, oily, volatile fluid, strongly acid in reaction. Similar
+glands are to be found in most of the Hemiptera-Heteroptera and their
+secretion is doubtless protective, through being disagreeable to the
+birds. In the bed-bug, as Marlatt points out, "it is probably an
+illustration of a very common phenomenon among animals, i.e., the
+persistence of a characteristic which is no longer of any special value
+to the possessor." In fact, its possession is a distinct disadvantage to
+the bed-bug, as the odor frequently reveals the presence of the bugs,
+before they are seen.
+
+The eggs of the bed-bug (fig. 70) are pearly white, oval in outline,
+about a millimeter long, and possess a small operculum or cap at one
+end, which is pushed off when the young hatches. They are laid
+intermittently, for a long period, in cracks and crevices of beds and
+furniture, under seams of mattresses, under loose wall paper, and
+similar places of concealment of the adult bugs. Girault (1905) observed
+a well-fed female deposit one hundred and eleven eggs during the
+sixty-one days that she was kept in captivity. She had apparently
+deposited some of her eggs before being captured.
+
+The eggs hatch in six to ten days, the newly emerged nymphs being about
+1.5 mm. in length and of a pale yellowish white color. They grow slowly,
+molting five times. At the last molt the mesathoracic wing pads appear,
+characteristic of the adult. The total length of the nymphal stage
+varies greatly, depending upon conditions of food supply, temperature
+and possibly other factors. Marlatt (1907) found under most favorable
+conditions a period averaging eight days between molting which, added to
+an equal egg period, gave a total of about seven weeks from egg to adult
+insect. Girault (1912) found the postembryonic period as low as
+twenty-nine days and as high as seventy days under apparently similar
+and normal conditions of food supply. Under optimum and normal
+conditions of food supply, beginning August 27, the average nymphal life
+was 69.9 days; average number of meals 8.75 and the molts 5. Under
+conditions allowing about half the normal food supply the average
+nymphal life was from 116.9 to 139 days. Nymphs starved from birth lived
+up to 42 days. We have kept unfed nymphs, of the first stage, alive in a
+bottle for 75 days. The interesting fact was brought out that under
+these conditions of minimum food supply there were sometimes six molts
+instead of the normal number.
+
+The adults are remarkable for their longevity, a factor which is of
+importance in considering the spread of the insect and methods of
+control. Dufour (1833) (not De Geer, as often stated) kept specimens for
+a year, in a closed vial, without food. This ability, coupled with their
+willingness to feed upon mice, bats, and other small mammals, and even
+upon birds, accounts for the long periods that deserted houses and camps
+may remain infested. There is no evidence that under such conditions
+they are able to subsist on the starch of the wall paper, juices of
+moistened wood, or the moisture in the accumulations of dust, as is
+often stated.
+
+There are three or four generations a year, as Girault's breeding
+experiments have conclusively shown. He found that the bed-bug does not
+hibernate where the conditions are such as to allow it to breed and that
+breeding is continuous unless interrupted by the lack of food or, during
+the winter, by low temperature.
+
+Bed-bugs ordinarily crawl from their hiding places and attack the face
+and neck or uncovered parts of the legs and arms of their victims. If
+undisturbed, they will feed to repletion. We have found that the young
+nymph would glut itself in about six minutes, though some individuals
+fed continuously for nine minutes, while the adult required ten to
+fifteen minutes for a full meal. When gorged, it quickly retreats to a
+crack or crevice to digest its meal, a process which requires two or
+three days. The effect of the bite depends very greatly on the
+susceptibility of the individual attacked. Some persons are so little
+affected that they may be wholly ignorant of the presence of a large
+number of bugs. Usually the bite produces a small hard swelling, or
+wheal, whitish in color. It may even be accompanied by an edema and a
+disagreeable inflammation, and in such susceptible individuals the
+restlessness and loss of sleep due to the presence of the insects may be
+a matter of considerable importance. Stiles (1907) records the case of a
+young man who underwent treatment for neurasthenia, the diagnosis being
+agreed upon by several prominent physicians; all symptoms promptly
+disappeared, however, immediately following a thorough fumigation of
+his rooms, where nearly a pint of bed-bugs were collected.
+
+It is natural to suppose that an insect which throughout its whole life
+is in such intimate relationship with man should play an important rôle
+in the transmission of disease. Yet comparatively little is definitely
+known regarding the importance of the bed-bug in this respect. It has
+been shown that it is capable of transmitting the bubonic plague, and
+South American trypanosomiasis. Nuttall succeeded in transmitting
+European relapsing fever from mouse to mouse by its bite. It has been
+claimed that Oriental sore, tuberculosis, and even syphilis may be so
+carried. These phases of the subject will be considered later.
+
+The sources of infestation are many, and the invasion of a house is not
+necessarily due to neglect, though the continued presence of the pests
+is quite another matter. In apartments and closely placed houses they
+are known to invade new quarters by migration. They are frequently to be
+met with in boat and sleeper berths, and even the plush seats of day
+coaches, whence a nucleus may be carried in baggage to residences. They
+may be brought in the laundry or in clothes of servants.
+
+Usually they are a great scourge in frontier settlements and it is
+generally believed that they live in nature under the bark of trees, in
+lumber, and under similar conditions. This belief is founded upon the
+common occurrence of bugs resembling the bed-bug, in such places. As a
+matter of fact, they are no relation to bed-bugs but belong to
+plant-feeding forms alone (fig. 19 _c_, _d_).
+
+It is also often stated that bed-bugs live in poultry houses, in
+swallows nests, and on bats, and that it is from these sources that they
+gain access to dwellings. These bugs are specifically distinct from the
+true bed-bug, but any of them may, rarely, invade houses. Moreover,
+chicken houses are sometimes thoroughly infested with the true _Cimex
+lectularius_.
+
+Control measures consist in the use of iron bedsteads and the reduction
+of hiding places for the bugs. If the infestation is slight they may be
+exterminated by a vigilant and systematic hunt, and by squirting
+gasoline or alcohol into cracks and crevices of the beds, and furniture.
+Fumigation must be resorted to in more general infestations.
+
+The simplest and safest method of fumigation is by the use of flowers of
+sulphur at the rate of two pounds to each one thousand cubic feet of
+room space. The sulphur should be placed in a pan, a well made in the
+top of the pile and a little alcohol poured in, to facilitate burning.
+The whole should be placed in a larger pan and surrounded by water so as
+to avoid all danger of fire. Windows should be tightly closed, beds,
+closets and drawers opened, and bedding spread out over chairs in order
+to expose them fully to the fumes. As metal is tarnished by the sulphur
+fumes, ornaments, clocks, instruments, and the like should be removed.
+When all is ready the sulphur should be fired, the room tightly closed
+and left for twelve to twenty-four hours. Still more efficient in large
+houses, or where many hiding places favor the bugs, is fumigation with
+hydrocyanic acid gas. This is a deadly poison and must be used under
+rigid precautions. Through the courtesy of Professor Herrick, who has
+had much experience with this method, we give in the Appendix, the clear
+and detailed directions taken from his bulletin on "Household Insects."
+
+Fumigation with formaldehyde gas, either from the liquid or "solid"
+formalin, so efficient in the case of contagious diseases, is useless
+against bed-bugs and most other insects.
+
+
+OTHER BED-BUGS--_Cimex hemipterus_ (= _C. rotundatus_) is a tropical and
+subtropical species, occurring in both the old and new world. Patton and
+Cragg state that it is distributed throughout India, Burma, Assam, the
+Malay Peninsula, Aden, the Island of Mauritius, Reunion, St. Vincent and
+Porto Rico. "It is widely distributed in Africa, and is probably the
+common species associated there with man." Brumpt also records it for
+Cuba, the Antilles, Brazil, and Venezuela.
+
+This species, which is sometimes called the Indian bed-bug, differs from
+_C. lectularius_ in being darker and in having a more elongate abdomen.
+The head also is shorter and narrower, and the prothorax has rounded
+borders.
+
+It has the same habits and practically the same life cycle as _Cimex
+lectularius_. Mackie, in India, has found that it is capable of
+transmitting the Asiatic type of recurrent fever. Roger suggested that
+it was also capable of transmitting Kala-azar and Patton has described
+in detail the developmental stages of _Leishmania_, the causative
+organism of Kala-azar, in the stomach of this bug, but Brumpt declares
+that the forms described are those of a common, non-pathogenic
+flagellate to be found in the bug, and have nothing to do with the
+human disease. Brumpt has shown experimentally that _Cimex hemipterus_
+may transmit _Trypanosoma cruzi_ in its excrement.
+
+_Cimex boueti_, occurring in French Guinea, is another species attacking
+man. Its habits and general life history are the same as for the above
+species. It is 3 to 4.5 mm. in length, has vestigial elytra, and much
+elongated antennæ and legs. The extended hind legs are about as long as
+the body.
+
+_Cimex columbarius_, a widely distributed species normally living in
+poultry houses and dove cotes, _C. inodorus_, infesting poultry in
+Mexico, _C. hirundinis_, occurring in the nests of swallows in Europe
+and _Oeciacus vicarius_ (fig. 19i) occurring in swallows' nests in this
+country, are species which occasionally infest houses and attack man.
+
+[Illustration: 71. Conorhinus sanguisugus.]
+
+_Conorhinus sanguisugus_, the cone-nosed bed-bug. We have seen in our
+consideration of poisonous insects, that various species of Reduviid
+bugs readily attack man. Certain of these are nocturnal and are so
+commonly found in houses that they have gained the name, of "big
+bed-bugs." The most noted of these, in the United States, is _Conorhinus
+sanguisugus_ (fig. 71), which is widely distributed in our Southern
+States.
+
+Like its near relatives, _Conorhinus sanguisugus_ is carnivorous in
+habit and feeds upon insects as well as upon mammalian and human blood.
+It is reported as often occurring in poultry houses and as attacking
+horses in barns. The life history has been worked out in considerable
+detail by Marlatt, (1902), from whose account we extract the following.
+
+[Illustration: 72. Beak of Conorhinus sanguisugus. After Marlatt.]
+
+The eggs are white, changing to yellow and pink before hatching. The
+young hatch within twenty days and there are four nymphal stages. In all
+these stages the insect is active and predaceous, the mouth-parts (fig.
+72) being powerfully developed. The eggs are normally deposited, and the
+early stages are undoubtedly passed, out of doors, the food of the
+immature forms being other insects. Immature specimens are rarely found
+indoors. It winters both in the partly grown and adult stage, often
+under the bark of trees or in any similar protection, and only in its
+nocturnal spring and early summer flights does it attack men. Marlatt
+states that this insect seems to be decidedly on the increase in the
+region which it particularly infests,--the plains region from Texas
+northward and westward. In California a closely related species of
+similar habits is known locally as the "monitor bug."
+
+The effect of the bite of the giant bed-bug on man is often very severe,
+a poisonous saliva apparently being injected into the wound. We have
+discussed this phase of the subject more fully under the head of
+poisonous insects.
+
+_Conorhinus megistus_ is a Brazilian species very commonly attacking
+man, and of special interest since Chagas has shown that it is the
+carrier of a trypanosomiasis of man. Its habits and life history have
+been studied in detail by Neiva, (1910).
+
+This species is now pre-eminently a household insect, depositing its
+eggs in cracks and crevices in houses, though this is a relatively
+recent adaptation. The nymphs emerge in from twenty to forty days,
+depending upon the temperature. There are five nymphal stages, and as in
+the case of true bed-bugs, the duration of these is very greatly
+influenced by the availability of food and by temperature. Neiva reckons
+the entire life cycle, from egg to egg, as requiring a minimum of three
+hundred and twenty-four days.
+
+The nymphs begin to suck blood in three to five days after hatching.
+They usually feed at night and in the dark, attacking especially the
+face of sleeping individuals. The bite occasions but little pain. The
+immature insects live in cracks and crevices in houses and invade the
+beds which are in contact with walls, but the adults are active flyers
+and attack people sleeping in hammocks. The males as well as the females
+are blood suckers.
+
+Like many blood-sucking forms, _Conorhinus megistus_ can endure for long
+periods without food. Neiva received a female specimen which had been
+for fifty-seven days alive in a tightly closed box. They rarely feed on
+two consecutive days, even on small quantities of blood, and were never
+seen to feed on three consecutive days.
+
+Methods of control consist in screening against the adult bugs, and the
+elimination of crevices and such hiding places of the nymphs. Where the
+infestation is considerable, fumigation with sulphur is advisable.
+
+
+PARASITIC DIPTERA OR FLIES
+
+Of the DIPTERA or two-winged flies, many species occasionally attack
+man. Of these, a few are outstanding pests, many of them may also serve
+to disseminate disease, a phase of our subject which will be considered
+later. We shall now consider the most important of the group from the
+viewpoint of their direct attacks on man.
+
+
+Psychodidæ or Moth-Flies
+
+The PSYCHODIDÆ or Moth-flies, include a few species which attack man,
+and at least one species, _Phlebotomus papatasii_, is known to transmit
+the so-called "three-day fever" of man. Another species is supposed to
+be the vector of Peruvian verruga.
+
+The family is made up of small, sometimes very small, nematocerous
+Diptera, which are densely covered with hairs, giving them a moth-like
+appearance. The wings are relatively large, oval or lanceolate in shape,
+and when at rest are held in a sloping manner over the abdomen, or are
+held horizontally in such a way as to give the insect a triangular
+outline. Not only is the moth-like appearance characteristic, but the
+venation of the wings (fig. 163, d) is very peculiar and, according to
+Comstock, presents an extremely generalized form. All of the
+longitudinal veins separate near the base of the wing except veins R_2
+and R_3 and veins M_1 and M_2. Cross veins are wanting in most cases.
+
+Comparatively little is known regarding the life-history and habits of
+the Psychodidæ, but one genus, _Phlebotomus_, contains minute,
+blood-sucking species, commonly known as sand-flies. The family is
+divided into two subfamilies, the PSYCHODINÆ and the PHLEBOTOMINÆ. The
+second of these, the PHLEBOTOMINÆ, is of interest to us.
+
+
+THE PHLEBOTOMINÆ--The Phlebotominæ differ from the Psychodinæ in that
+the radical sector branches well out into the wing rather than at the
+base of the wing. They are usually less hairy than the Psychodinæ. The
+ovipositor is hidden and less strongly chitinized. The species attacking
+man belong to the genus _Phlebotomus_, small forms with relatively
+large, hairy wings which are held upright, and with elongate proboscis.
+The mandibles and maxillæ are serrated and fitted for biting.
+
+According to Miss Summers (1913) there are twenty-nine known species of
+the genus _Phlebotomus_, five European, eleven Asiatic, seven African
+and six American. One species only, _Phlebotomus vexator_, has been
+reported for the United States. This was described by Coquillett,
+(1907), from species taken on Plummer's Island, Maryland. It measures
+only 1.5 mm. in length. As it is very probable that this species is much
+more widely distributed, and that other species of these minute flies
+will be found to occur in our fauna, we quote Coquillett's description.
+
+_Phlebotomus vexator_, Coq.: Yellow, the mesonotum brown, hairs chiefly
+brown; legs in certain lights appear brown, but are covered with a white
+tomentum; wings hyaline, unmarked; the first vein (R_1) terminates
+opposite one-fifth of the length of the first submarginal cell (cell
+R_2); this cell is slightly over twice as long as its petiole; terminal,
+horny portion of male claspers slender, bearing many long hairs; the
+apex terminated by two curved spines which are more than one-half as
+long as the preceding part, and just in front of these are two similar
+spines, while near the middle of the length of this portion is a fifth
+spine similar to the others. Length 1.5 mm.
+
+The life-history of the Phlebotomus flies has been best worked out for
+the European _Phlebotomus papatasii_ and we shall briefly summarize the
+account of DÅ“rr and Russ (1913) based primarily on work on this
+species. The European Phlebotomus flies appear at the beginning of the
+warm season, a few weeks after the cessation of the heavy rains and
+storms of springtime. They gradually become more abundant until they
+reach their first maximum, which in Italy is near the end of July
+(Grassi). They then become scarcer but reach a second maximum in
+September. At the beginning of winter they vanish completely,
+hibernating individuals not being found.
+
+After fertilization there is a period of eight to ten days before
+oviposition. The eggs are then deposited, the majority in a single mass
+covered by a slimy secretion from the sebaceous glands. The larvæ emerge
+in fourteen to twenty days. There is uncertainty as to the length of
+larval life, specimens kept in captivity remaining fifty or more days
+without transforming. Growth may be much more rapid in nature. The larvæ
+do not live in fluid media but in moist detritus in dark places. Marett
+believes that they live chiefly on the excrement of pill-bugs (Oniscidæ)
+and lizards. Pupation always occurs during the night. The remnants of
+the larval skin remain attached to the last two segments of the
+quiescent pupa and serve to attach it to the stone on which it lives.
+The pupal stage lasts eleven to sixteen days, the adult escaping at
+night.
+
+Only the females suck blood. They attack not only man but all
+warm-blooded animals and, according to recent workers, also cold-blooded
+forms, such as frogs, lizards, and larvæ. Indeed, Townsend (1914)
+believes that there is an intimate relation between _Phlebotomus_ and
+lizards, or other reptiles the world over. The Phlebotomus passes the
+daylight hours within the darkened recesses of the loose stone walls and
+piles of rock in order to escape wind and strong light. Lizards inhabit
+the same places, and the flies, always ready to suck blood in the
+absence of light and wind, have been found more prone to suck reptilian
+than mammalian blood.
+
+On hot summer nights, when the wind is not stirring, the Phlebotomus
+flies, or sand-flies, as they are popularly called, invade houses and
+sleeping rooms in swarms and attack the inmates. As soon as light begins
+to break the flies either escape to the breeding places, or cool, dark
+places protected from the wind, or a part of them remain in the rooms,
+hiding behind pictures, under garments, and in similar places. Wherever
+the Phlebotomus flies occur they are an intolerable nuisance. On account
+of their small size they can easily pass through the meshes of ordinary
+screens and mosquito curtains. They attack silently and inflict a very
+painful, stinging bite, followed by itching. The ankles, dorsum of the
+feet, wrists, inner elbow, knee joint and similar places are favorite
+places of attack, possibly on account of their more delicate skin.
+
+Special interest has been attracted to these little pests in recent
+years, since it has been shown that they transmit the European
+"pappatici fever" or "three day fever." More recently yet, it appears
+that they are the carriers of the virus of the Peruvian "verruga." This
+phase of the subject will be discussed later.
+
+Control measures have not been worked out. As Newstead says, "In
+consideration of the facts which have so far been brought to light
+regarding the economy of Phlebotomus, it is clearly evident that the
+task of suppressing these insects is an almost insurmountable one. Had
+we to deal with insects as large and as accessible as mosquitoes, the
+adoption of prophylactic measures would be comparatively easy, but owing
+to the extremely minute size and almost flea-like habits of the adult
+insects, and the enormous area over which the breeding-places may occur,
+we are faced with a problem which is most difficult of solution." For
+these reasons, Newstead considers that the only really prophylactic
+measures which can at present be taken, are those which are considered
+as precautionary against the bites of the insects.
+
+Of repellents, he cites as one of the best a salve composed of the
+following:
+
+  Ol. Anisi                                                    3 grs.
+  Ol. Eucalypti                                                3 grs.
+  Ol. Terebenth                                                3 grs.
+  Unq. Acid Borac.
+
+Of sprays he recommends as the least objectionable and at the same time
+one of the most effective, formalin. "The dark portions and angles of
+sleeping apartments should be sprayed with a one per cent. solution of
+this substance every day during the season in which the flies are
+prevalent. A fine spraying apparatus is necessary for its application
+and an excessive amount must not be applied. It is considered an
+excellent plan also to spray the mosquito curtains regularly every day
+towards sunset; nets thus treated are claimed to repel the attacks of
+these insects." This effectiveness of formalin is very surprising for,
+as we have seen, it is almost wholly ineffective against bed-bugs,
+mosquitoes, house flies and other insects, where it has been tried.
+
+A measure which promises to be very effective, where it can be adopted,
+is the use of electric fans so placed as to produce a current of air in
+the direction of the windows of sleeping apartments. On account of the
+inability of the Phlebotomus flies to withstand even slight breezes, it
+seems very probable that they would be unable to enter a room so
+protected.
+
+
+Culicidæ or Mosquitoes
+
+From the medical viewpoint, probably the most interesting and important
+of the blood-sucking insects are the mosquitoes. Certainly this is true
+of temperate zones, such as those of the United States. The result is
+that no other group of insects has aroused such widespread interest, or
+has been subjected to more detailed study than have the mosquitoes,
+since their rôle as carriers of disease was made known. There is an
+enormous literature dealing with the group, but fortunately for the
+general student, this has been well summarized by a number of workers.
+The most important and helpful of the general works are those of Howard
+(1901), Smith (1904), Blanchard (1905), Mitchell (1907), and especially
+of Howard, Dyar, and Knab, whose magnificent monograph is still in
+course of publication.
+
+Aside from their importance as carriers of disease, mosquitoes are
+notorious as pests of man, and the earlier literature on the group is
+largely devoted to references to their enormous numbers and their
+blood-thirstiness in certain regions. They are to be found in all parts
+of the world, from the equator to the Arctic and Antarctic regions.
+Linnæus, in the "Flora Lapponica," according to Howard, Dyar and Knab,
+"dwells at some length upon the great abundance of mosquitoes in Lapland
+and the torments they inflicted upon man and beast. He states that he
+believes that nowhere else on earth are they found in such abundance and
+he compares their numbers to the dust of the earth. Even in the open,
+you cannot draw your breath without having your mouth and nostrils
+filled with them; and ointments of tar and cream or of fish grease are
+scarcely sufficient to protect even the case-hardened cuticle of the
+Laplander from their bite. Even in their cabins, the natives cannot take
+a mouthful of food or lie down to sleep unless they are fumigated almost
+to suffocation." In some parts of the Northwestern and Southwestern
+United States it is necessary to protect horses working in the fields by
+the use of sheets or burlaps, against the ferocious attacks of these
+insects. It is a surprising fact that even in the dry deserts of the
+western United States they sometimes occur in enormous numbers.
+
+Until comparatively recent years, but few species of mosquitoes were
+known and most of the statements regarding their life-history were based
+upon the classic work of Reaumur (1738) on the biology of the rain
+barrel mosquito, _Culex pipiens_. In 1896, Dr. Howard refers to
+twenty-one species in the United States, now over fifty are known;
+Giles, in 1900, gives a total of two hundred and forty-two for the world
+fauna, now over seven hundred species are known. We have found eighteen
+species at Ithaca, N. Y.
+
+All of the known species of mosquitoes are aquatic in the larval stage,
+but in their life-histories and habits such great differences occur that
+we now know that it is not possible to select any one species as typical
+of the group. For our present purpose we shall first discuss the general
+characteristics and structure of mosquitoes, and shall then give the
+life-history of a common species, following this by a brief
+consideration of some of the more striking departures from what have
+been supposed to be the typical condition.
+
+The CULICIDÆ are slender, nematocerous Diptera with narrow wings,
+antennæ plumose in the males, and usually with the proboscis much longer
+than the head, slender, firm and adapted for piercing in the female.
+The most characteristic feature is that the margins of the wings and, in
+most cases, the wing veins possess a fringe of scale-like hairs. These
+may also cover in part, or entirely, the head, thorax, abdomen and legs.
+The females, only, suck blood.
+
+On account of the importance of the group in this country and the
+desirability of the student being able to determine material in various
+stages, we show in the accompanying figures the characters most used in
+classification.
+
+The larvæ (fig. 73) are elongate, with the head and thorax sharply
+distinct. The larval antennæ are prominent, consisting of a single
+cylindrical and sometimes curved segment. The outer third is often
+narrower and bears at its base a fan-shaped tuft of hairs, the
+arrangement and abundance of which is of systematic importance. About
+the mouth are the so-called rotary mouth brushes, dense masses of long
+hairs borne by the labrum and having the function of sweeping food into
+the mouth. The form and arrangement of thoracic, abdominal, and anal
+tufts of hair vary in different species and present characteristics of
+value. On either side of the eighth abdominal segment is a patch of
+scales varying greatly in arrangement and number and of much value in
+separating species. Respiration is by means of tracheæ which open at the
+apex of the so-called anal siphon, when it is present. In addition,
+there are also one or two pairs of tracheal gills which vary much in
+appearance in different species. On the ventral side of the anal siphon
+is a double row of flattened, toothed spines whose number and shape are
+likewise of some value in separating species. They constitute the comb
+or pecten.
+
+[Illustration: 73. Culex larva showing details of external structure.]
+
+The pupa (fig. 139, b) unlike that of most insects, is active, though it
+takes no food. The head and thorax are not distinctly separated, but the
+slender flexible abdomen in sharply marked off. The antennæ,
+mouth-parts, legs, and wings of the future adult are now external, but
+enclosed in chitinous cases. On the upper surface, near the base of the
+wings are two trumpets, or breathing tubes, for the pupal spiracles are
+towards the anterior end instead of at the caudal end, as in the larva.
+At the tip of the abdomen is a pair of large chitinous swimming paddles.
+
+As illustrative of the life cycle of a mosquito we shall discuss the
+development of a common house mosquito, _Culex pipiens_, often referred
+to in the Northern United States as the rain barrel mosquito. Its life
+cycle is often given as typical for the entire group, but, as we have
+already emphasized, no one species can serve this purpose.
+
+The adults of _Culex pipiens_ hibernate throughout the winter in
+cellars, buildings, hollow trees, or similar dark shelters. Early in the
+spring they emerge and deposit their eggs in a raft-like mass. The
+number of eggs in a single mass is in the neighborhood of two hundred,
+recorded counts varying considerably. A single female may deposit
+several masses during her life time. The duration of the egg stage is
+dependent upon temperature. In the warm summer time the larvæ may emerge
+within a day. The larvæ undergo four molts and under optimum conditions
+may transform into pupæ in about a week's time. Under the same favorable
+conditions, the pupal stage may be completed in a day's time. The total
+life cycle of _Culex pipiens_, under optimum conditions, may thus be
+completed in a week to ten days. This period may be considerably
+extended under less favorable conditions of temperature and food supply.
+
+_Culex pipiens_ breeds continuously throughout the summer, developing in
+rain barrels, horse troughs, tin cans, or indeed in any standing water
+about houses, which lasts for a week or more. The catch basins of sewers
+furnish an abundant supply of the pests under some conditions. Such
+places, the tin gutters on residences, and all possible breeding places
+must be considered in attempts to exterminate this species.
+
+Other species of mosquitoes may exhibit radical departures from _Culex
+pipiens_ in life-history and habits. To control them it is essential
+that the biological details be thoroughly worked out for, as Howard,
+Dyar, and Knab have emphasized, "much useless labor and expense can be
+avoided by an accurate knowledge of the habits of the species." For a
+critical discussion of the known facts the reader is referred to their
+monograph. We shall confine ourselves to a few illustrations.
+
+The majority of mosquitoes in temperate climates hibernate in the egg
+stage, hatching in the spring or even mild winter days in water from
+melting snow. It is such single-brooded species which appear in
+astounding numbers in the far North. Similarly, in dry regions the eggs
+may stand thorough dessication, and yet hatch out with great promptness
+when submerged by the rains. "Another provision to insure the species
+against destruction in such a case, exists in the fact * * * that not
+all the eggs hatch, a part of them lying over until again submerged by
+subsequent rains." In temperate North America, a few species pass the
+winter in the larval state. An interesting illustration of this is
+afforded by _Wyeomia smithii_, whose larvæ live in pitcher plants and
+are to be found on the coldest winter days imbedded in the solid ice.
+Late in the spring, the adults emerge and produce several broods during
+the summer.
+
+In the United States, one of the most important facts which has been
+brought out by the intensive studies of recent years is that certain
+species are migratory and that they can travel long distances and become
+an intolerable pest many miles from their breeding places. This was
+forcibly emphasized in Dr. Smith's work in New Jersey, when he found
+that migratory mosquitoes, developing in the salt marshes along the
+coast, are the dominant species largely responsible for the fame of the
+New Jersey mosquito. The species concerned are _Aedes sollicitans_, _A.
+cantator_ and _A. tæniorhynchus_. Dr. Smith decided that the first of
+these might migrate at least forty miles inland. It is obvious that
+where such species are the dominant pest, local control measures are a
+useless waste of time and money. Such migratory habits are rare,
+however, and it is probable that the majority of mosquitoes do not fly
+any great distance from their breeding places.
+
+While mosquitoes are thought of primarily as a pest of man, there are
+many species which have never been known to feed upon human or mammalian
+blood, no matter how favorable the opportunity. According to Howard,
+Dyar, and Knab, this is true of _Culex territans_, one of the common
+mosquitoes in the summer months in the Northern United States. There are
+some species, probably many, in which the females, like the males, are
+plant feeders. In experimental work, both sexes are often kept alive for
+long periods by feeding them upon ripe banana, dried fig, raisins, and
+the like, and in spite of sweeping assertions that mosquitoes must have
+a meal of blood in order to stimulate the ovaries to development, some
+of the common blood-sucking species, notably _Culex pipiens_, have been
+bred repeatedly without opportunity to feed upon blood.
+
+The effect of the bite varies greatly with different species and depends
+upon the susceptibility of the individual bitten. Some persons are
+driven almost frantic by the attacks of the pests when their companions
+seem almost unconscious of any inconvenience. Usually, irritation and
+some degree of inflammation appear shortly following the bite. Not
+infrequently a hardened wheal or even a nodule forms, and sometimes
+scratching leads to secondary infection and serious results.
+
+The source of the poison is usually supposed to be the salivary glands
+of the insect. As we have already pointed out, (p. 34), Macloskie
+believed that one lobe of the gland, on each side, was specialized for
+forming the poison, while a radically different view is that of
+Schaudinn, who believed that the irritation is due to the expelled
+contents of the Å“sophageal diverticula, which contain a gas and a
+peculiar type of fungi or bacteria. In numerous attempts, Schaudinn was
+unable to produce any irritation by applying the triturated salivary
+glands to a wound, but obtained the typical result when he used the
+isolated diverticula.
+
+The irritation of the bite may be relieved to some extent by using
+ammonia water, a one per cent. alcoholic solution of menthol, or
+preparations of cresol, or carbolic acid. Dr. Howard recommends rubbing
+the bite gently with a piece of moist toilet soap. Castellani and
+Chalmers recommend cleansing inflamed bites with one in forty carbolic
+lotion, followed by dressing with boracic ointment. Of course,
+scratching should be avoided as much as possible.
+
+Repellents of various kinds are used, for warding off the attacks of the
+insects. We have often used a mixture of equal parts of oil of
+pennyroyal and kerosene, applied to the hands and face. Oil of
+citronella is much used and is less objectionable to some persons. A
+recommended formula is, oil of citronella one ounce, spirits of camphor
+one ounce, oil of cedar one-half ounce. A last resort would seem to be
+the following mixture recommended by Howard, Dyar, and Knab for use by
+hunters and fishermen in badly infested regions, against mosquitoes and
+blackflies.
+
+Take 2¼ lbs. of mutton tallow and strain it. While still hot add ½
+lb. black tar (Canadian tar). Stir thoroughly and pour into the
+receptacle in which it is to be contained. When nearly cool stir in
+three ounces of oil of citronella and 1¼ oz. of pennyroyal.
+
+At night the surest protection is a good bed net. There are many types
+of these in use, but in order to be serviceable and at the same time
+comfortable it should be roomy and hung in such a way as to be stretched
+tightly in every direction. We prefer one suspended from a broad, square
+frame, supported by a right-angled standard which is fastened to the
+head of the bed. It must be absolutely free from rents or holes and
+tucked in securely under the mattress or it will serve merely as a
+convenient cage to retain mosquitoes which gain an entrance. While such
+nets are a convenience in any mosquito ridden community, they are
+essential in regions where disease-carrying species abound. Screening of
+doors, windows and porches, against the pests is so commonly practiced
+in this country that its importance and convenience need hardly be
+urged.
+
+Destruction of mosquitoes and prevention of breeding are of fundamental
+importance. Such measures demand first, as we have seen, the correct
+determination of the species which is to be dealt with, and a knowledge
+of its life-history and habits. If it prove to be one of the migratory
+forms, it is beyond mere local effort and becomes a problem demanding
+careful organization and state control. An excellent illustration of the
+importance and effectiveness of work along these lines is afforded by
+that in New Jersey, begun by the late Dr. John B. Smith and being pushed
+with vigor by his successor, Dr. Headlee.
+
+In any case, there is necessity for community action. Even near the
+coast, where the migratory species are dominant, there are the local
+species which demand attention and which cannot be reached by any
+measures directed against the species of the salt marshes. The most
+important of local measures consist in the destruction of breeding
+places by filling or draining ponds and pools, clearing up of more
+temporary breeding places, such as cans, pails, water barrels and the
+like. Under conditions where complete drainage of swamps is
+impracticable or undesirable, judicious dredging may result in a pool or
+series of steep-sided pools deep enough to maintain a supply of fish,
+which will keep down the mosquito larvæ. Where water receptacles are
+needed for storage of rain water, they should be protected by careful
+screening or a film of kerosene over the top of the water, renewed every
+two weeks or so, so as to prevent mosquitoes from depositing their eggs.
+When kerosene is used, Water drawn from the bottom of the receptacle
+will not be contaminated by it to any injurious extent. Where ponds
+cannot be drained much good will be accomplished by spraying kerosene
+oil on the surface of the water, or by the introduction of fish which
+will feed on the larvæ.
+
+Detailed consideration of the most efficient measures for controlling
+mosquitoes is to be found in Dr. Howard's Bulletin No. 88 of the Bureau
+of Entomology, "Preventive and remedial work against mosquitoes" or, in
+more summarized form, in Farmers' Bulletin No. 444. One of these should
+be obtained by any person interested in the problems of mosquito control
+and public health.
+
+[Illustration: 74. Mouth parts of Simulium. After Grünberg.]
+
+
+The Simuliidæ, or Black Flies
+
+The SIMULIIDÆ, or black flies, are small, dark, or black flies, with a
+stout body and a hump-back appearance. The antennæ are short but
+eleven-segmented, the wings broad, without scales or hairs, and with the
+anterior veins stout but the others very weak. The mouth-parts (fig. 74)
+are fitted for biting.
+
+The larvæ of the Simuliidæ (fig. 75) are aquatic and, unlike those of
+mosquitoes, require a well ærated, or swiftly running water. Here they
+attach to stones, logs, or vegetation and feed upon various
+micro-organisms. They pupate in silken cocoons open at the top. Detailed
+life-histories have not been worked out for most of the species. We
+shall consider as typical that of _Simulium pictipes_, an inoffensive
+species widely distributed in the Eastern United States, which has been
+studied especially at Ithaca, N.Y. (Johannsen, 1903).
+
+[Illustration: 75. Larva of Simulium, (×8). After Garman.]
+
+The eggs are deposited in a compact yellowish layer on the surface of
+rock, on the brinks of falls and rapids where the water is flowing
+swiftly. They are elongate ellipsoidal in shape, about .4 by .18 mm. As
+myriads of females deposit in the same place the egg patches may be
+conspicuous coatings of a foot or much more in diameter. When first laid
+they are enveloped in a yellowish white slime, which becomes darker,
+until finally it becomes black just before the emerging of the larvæ.
+The egg stage lasts a week.
+
+The larvæ (fig. 75) are black, soft skinned, somewhat cylindrical in
+shape, enlarged at both ends and attenuated in the middle. The posterior
+half is much stouter than the anterior part and almost club-shaped. The
+head bears two large fan-shaped organs which aid in procuring food.
+Respiration is accomplished by means of three so-called blood gills
+which are pushed out from the dorsal part of the rectum. The larvæ occur
+in enormous numbers, in moss-like patches. If removed from their natural
+habitat and placed in quiet water they die within three or four hours.
+Fastened to the rock by means of a disk-like sucker at the caudal end of
+the body, they ordinarily assume an erect position. They move about on
+the surface of the rocks, to a limited extent, with a looping gait
+similar to that of a measuring worm, and a web is secreted which
+prevents their being washed away by the swiftly flowing water. They feed
+chiefly upon algæ and diatoms.
+
+The complete larval stage during the summer months occupies about four
+weeks, varying somewhat with the temperature and velocity of the water.
+At the end of this period they spin from cephalic glands, boot-shaped
+silken cocoons within which they pupate. The cocoon when spun is firmly
+attached to the rock and also to adjacent cocoons. Clustered
+continuously over a large area and sometimes one above another, they
+form a compact, carpet-like covering on the rocks, the reddish-brown
+color of which is easily distinguishable from the jet-black appearance
+of the larvæ. The pupal stage lasts about three weeks. The adult fly,
+surrounded by a bubble of air, quickly rises to the surface of the water
+and escapes. The adults (fig. 76) are apparently short lived and thus
+the entire life cycle, from egg to egg is completed in approximately
+eight weeks.
+
+[Illustration: 76. Simulium venustum, (×8). After Garman.]
+
+In the case of _Simulium pictipes_ at Ithaca, N. Y., the first brood of
+adults emerges early in May and successive generations are produced
+throughout the summer and early autumn. This species winters in the
+larval condition. Most of the other species of _Simulium_ which have
+been studied seem to be single brooded.
+
+While _Simulium pictipes_ does not attack man, there are a number of the
+species which are blood-sucking and in some regions they are a veritable
+scourge. In recent years the greatest interest in the group has been
+aroused by Sambon's hypothesis that they transmit pellagra from man to
+man. This has not been established, and, indeed, seems very doubtful,
+but the importance of these insects as pests and the possibility that
+they may carry disease make it urgent that detailed life-histories of
+the hominoxious species be worked out.
+
+As pests a vivid account of their attacks is in Agassiz's "Lake
+Superior" (p. 61), quoted by Forbes (1912).
+
+"Neither the love of the picturesque, however, nor the interests of
+science, could tempt us into the woods, so terrible were the black
+flies. This pest of flies which all the way hither had confined our
+ramblings on shore pretty closely to the rocks and the beach, and had
+been growing constantly worse, here reached its climax. Although
+detained nearly two days, * * * we could only sit with folded hands, or
+employ ourselves in arranging specimens, and such other operations as
+could be pursued in camp, and under the protection of a 'smudge.' One,
+whom scientific ardor tempted a little way up the river in a canoe,
+after water plants, came back a frightful spectacle, with blood-red
+rings round his eyes, his face bloody, and covered with punctures. The
+next morning his head and neck were swollen as if from an attack of
+erysipelas."
+
+There are even well authenticated accounts on record of death of humans
+from the attacks of large swarms of these gnats. In some regions, and
+especially in the Mississippi Valley in this country, certain species of
+black flies have been the cause of enormous losses to farmers and
+stockmen, through their attacks on poultry and domestic animals. C. V.
+Riley states that in 1874 the loss occasioned in one county in Tennessee
+was estimated at $500,000.
+
+The measures of prevention and protection against these insects have
+been well summarized by Forbes (1912). They are of two kinds: "the use
+of repellents intended to drive away the winged flies, and measures for
+the local destruction of the aquatic larvæ. The repellents used are
+either smudges, or surface applications made to keep the flies from
+biting. The black-fly will not endure a dense smoke, and the well-known
+mosquito smudge seems to be ordinarily sufficient for the protection of
+man. In the South, leather, cloth, and other materials which will make
+the densest and most stifling smoke, are often preserved for this use in
+the spring. Smudges are built in pastures for the protection of stock,
+and are kept burning before the doors of barns and stables. As the
+black-flies do not readily enter a dark room, light is excluded from
+stables as much as possible during the gnat season. If teams must be
+used in the open field while gnats are abroad, they may be protected
+against the attacks of the gnats by applying cotton-seed oil or axle
+grease to the surface, especially to the less hairy parts of the
+animals, at least twice a day. A mixture of oil and tar and, indeed,
+several other preventives, are of practical use in badly infested
+regions; but no definite test or exact comparison has been made with any
+them in a way to give a record of the precise results."
+
+"It is easy to drive the flies from houses or tents by burning pyrethrum
+powder inside; this either kills the flies or stupifies them so that
+they do not bite for some time thereafter." * * * "Oil of tar is
+commonly applied to the exposed parts of the body for the purpose of
+repelling the insects, and this preparation is supplied by the Hudson
+Bay Company to its employees. Minnesota fishermen frequently grease
+their faces and hands with a mixture of kerosene and mutton tallow for
+the same purpose." We have found a mixture of equal parts of kerosene
+and oil of pennyroyal efficient.
+
+Under most circumstances very little can be done to destroy this insect
+in its early stage, but occasionally conditions are such that a
+larvicide can be used effectively. Weed (1904), and Sanderson (1910)
+both report excellent results from the use of phinotas oil, a
+proprietary compound. The first-mentioned also found that in some places
+the larvæ could be removed by sweeping them loose in masses with stiff
+stable brooms and then catching them downstream on wire netting
+stretched in the water.
+
+
+Chironomidæ or Midges
+
+The flies of this family, commonly known as midges, resemble mosquitoes
+in form and size but are usually more delicate, and the wing-veins,
+though sometimes hairy, are not fringed with scales. The venation is
+simpler than in the mosquitoes and the veins are usually less distinct.
+
+These midges, especially in spring or autumn, are often seen in immense
+swarms arising like smoke over swamps and producing a humming noise
+which can be heard for a considerable distance. At these seasons they
+are frequently to be found upon the windows of dwellings, where they are
+often mistaken for mosquitoes.
+
+The larvæ are worm-like, but vary somewhat in form in the different
+genera. Most of them are aquatic, but a few live in the earth, in
+manure, decaying wood, under bark, or in the sap of trees, especially in
+the sap which collects in wounds.
+
+[Illustration: 77. Culicoides guttipennis; (_a_) adult, (×15); (_b_)
+head of same; (_c_) larva; (_d_) head; (_e_) pupa. After Pratt.]
+
+Of the many species of CHIRONOMIDÆ, (over eight hundred known), the vast
+majority are inoffensive. The sub-family Ceratopogoninæ, however, forms
+an exception, for some of the members of this group, known as sandflies,
+or punkies, suck blood and are particularly troublesome in the
+mountains, along streams, and at the seashore. Most of these have been
+classed under the genus _Ceratopogon_, but the group has been broken up
+into a number of genera and _Ceratopogon_, in the strict sense, is not
+known to contain any species which sucks the blood of vertebrates.
+
+THE CERATOPOGONINÆ--The Ceratopogoninæ are among the smallest of the
+Diptera, many of them being hardly a millimeter long and some not even
+so large. They are Chironomidæ in which the thorax is not prolonged over
+the head. The antennæ are filiform with fourteen (rarely thirteen)
+segments in both sexes, those of the male being brush-like. The basal
+segment is enlarged, the last segment never longer than the two
+preceding combined, while the last five are sub-equal to, or longer than
+the preceding segment. The legs are relatively stouter than in the other
+Chironomidæ. The following three genera of this subfamily are best known
+as blood suckers in this country.
+
+Of the genus _Culicoides_ there are many species occurring in various
+parts of the world. A number are known to bite man and animals and it is
+probable that all are capable of inflicting injury. In some localities
+they are called punkies, in others, sand-flies, a name sometimes also
+applied to the species of _Simulium_ and _Phlebotomus_. Owing to their
+very small size they are known by some tribes of Indians as No-see-ums.
+The larvæ are found in ponds, pools, water standing in hollow tree
+stumps, and the like. Though probably living chiefly in fresh water, we
+have found a species occurring in salt water. The larvæ are small,
+slender, legless, worm-like creatures (fig. 77_c_) with small brown head
+and twelve body segments. The pupæ (fig. 77_e_) are slender, more
+swollen at the anterior end and terminating in a forked process. They
+float nearly motionless in a vertical position, the respiratory tubes in
+contact with the surface film. The adults are all small, rarely
+exceeding 2¼ mm. in length. The wings are more or less covered with
+erect setulæ or hairs and in many species variously spotted and marked
+with iridescent blotches. The antennæ have fourteen segments, the palpi
+usually five. The wing venation and mouth-parts are shown in figures 77
+and 78. Of the twenty or more species of this genus occurring in the
+United States the following are known to bite: _C. cinctus_, _C.
+guttipennis_, _C. sanguisuga_, _C. stellifer_, _C. variipennis_, _C.
+unicolor_.
+
+[Illustration: 78. Culicoides guttipennis; mouth parts of adult. After
+Pratt.]
+
+One of the most widely distributed and commonest species in the Eastern
+States is _C. guttipennis_ (fig. 77a). It is black with brown legs, a
+whitish ring before the apex of each femur and both ends of each tibia;
+tarsi yellow, knobs of halteres yellow. Mesonotum opaque, brown, two
+vittæ in the middle, enlarging into a large spot on the posterior half,
+also a curved row of three spots in front of each wing, and the narrow
+lateral margins, light gray pruinose. Wings nearly wholly covered with
+brown hairs, gray, with markings as shown in the figure. Length one mm.
+
+_Johannseniella_ Will. is a wide-spread genus related to the foregoing.
+Its mouth-parts are well adapted for piercing and it is said to be a
+persistent blood sucker, particularly in Greenland. This genus is
+distinguished from _Culicoides_ by its bare wings, the venation (fig.
+163, c), and the longer tarsal claws. There are over twenty North
+American species.
+
+[Illustration: 79. Chrysops univittatus, (×4). After Osborn.]
+
+In the Southwestern United States, _Tersesthes torrens_ Towns. occurs, a
+little gnat which annoys horses, and perhaps man also, by its bite. It
+is related to _Culicoides_ but differs in the number of antennal
+segments and in its wing venation (fig. 163, e). The fly measures but
+two mm. in length and is blackish in color. The antennæ of the female
+have thirteen segments, the palpi but three, of which the second is
+enlarged and swollen.
+
+
+Tabanidæ or Horse-Flies
+
+The TABANIDÆ,--horse-flies, ear-flies, and deer-flies,--are well-known
+pests of cattle and horses and are often extremely annoying to man. The
+characteristics of the family and of the principal North American genera
+are given in the keys of Chapter XII. There are over 2500 recorded
+species. As in the mosquitoes, the females alone are blood suckers. The
+males are flower feeders or live on plant juices. This is apparently
+true also of the females of some of the genera.
+
+The eggs are deposited in masses on water plants or grasses and sedges
+growing in marshy or wet ground. Those of a common species of _Tabanus_
+are illustrated in figure 80, _a_. They are placed in masses of several
+hundred, light colored when first deposited but turning black. In a week
+or so the cylindrical larvæ, tapering at both ends (fig. 80, _b_),
+escape to the water, or damp earth, and lead an active, carnivorous
+life, feeding mainly on insect larvæ, and worms. In the forms which have
+been best studied the larval life is a long one, lasting for months or
+even for more than a year. Until recently, little was known concerning
+the life-histories of this group, but the studies of Hart (1895), and
+Hine (1903 +) have added greatly to the knowledge concerning North
+American forms.
+
+Many of the species attack man with avidity and are able to inflict
+painful bites, which may smart for hours. In some instances the wound is
+so considerable that blood will continue to flow after the fly has left.
+We have seen several cases of secondary infection following such bites.
+
+[Illustration: 80. (_a_) Eggs of Tabanus. Photograph by J. T. Lloyd.]
+
+[Illustration: 80. (_b_) Larva of Tabanus. Photograph by M. V. S.]
+
+The horse-flies have been definitely convicted of transferring the
+trypanosome of surra from diseased to healthy animals and there is good
+evidence that they transfer anthrax. The possibility of their being
+important agents in the conveyal of human diseases should not be
+overlooked. Indeed, Leiper has recently determined that a species of
+_Chrysops_ transfers the blood parasite _Filaria diurna_.
+
+
+Leptidæ or Snipe-Flies
+
+The family LEPTIDÆ is made up of moderate or large sized flies,
+predaceous in habit. They are sufficiently characterized in the keys of
+Chapter XII. Four blood-sucking species belonging to three genera have
+been reported. Of these _Symphoromyia pachyceras_ is a western species.
+Dr. J. C. Bradley, from personal experience, reports it as a vicious
+biter.
+
+[Illustration: 80. (_c_) Mouth parts of Tabanus. After Grünberg.]
+
+
+Oestridæ or Bot-flies
+
+To the family OESTRIDÆ belong the bot and warble-flies so frequently
+injurious to animals. The adults are large, or of medium size, heavy
+bodied, rather hairy, and usually resemble bees in appearance.
+
+The larvæ live parasitically in various parts of the body of mammals,
+such as the stomach (horse bot-fly), the subcutaneous connective tissue
+(warble-fly of cattle), or the nasal passage (sheep bot-fly or head
+maggot).
+
+There are on record many cases of the occurrence of the larvæ of
+Oestridæ as occasional parasites of man. A number of these have been
+collected and reviewed in a thesis by Mme. Pètrovskaia (1910). The
+majority of them relate to the following species.
+
+_Gastrophilus hæmorrhoidalis_, the red tailed bot-fly, is one of the
+species whose larvæ are most commonly found in the stomach of the horse.
+Schoch (1877) cites the case of a woman who suffered from a severe case
+of chronic catarrh of the stomach, and who vomited, and also passed from
+the anus, larvæ which apparently belonged to this species. Such cases
+are exceedingly rare but instances of subcutaneous infestation are
+fairly numerous. In the latter type these larvæ are sometimes the cause
+of the peculiar "creeping myasis." This is characterized at its
+beginning by a very painful swelling which gradually migrates, producing
+a narrow raised line four to twenty-five millimeters broad. When the
+larva is mature, sometimes after several months, it becomes stationary
+and a tumor is formed which opens and discharges the larva along with
+pus and serum.
+
+_Gastrophilus equi_ is the most widespread and common of the horse
+bot-flies. Portschinsky reports it as commonly causing subcutaneous
+myasis of man in Russia.
+
+_Hypoderma bovis_ (= _Oestrus bovis_), and _Hypoderma lineata_ are the
+so-called warble-flies of cattle. The latter species is the more common
+in North America but Dr. C. G. Hewitt has recently shown that _H. bovis_
+also occurs. Though warbles are very common in cattle in this country,
+the adult flies are very rarely seen. They are about half an inch in
+length, very hairy, dark, and closely resemble common honey-bees.
+
+They deposit their eggs on the hairs of cattle and the animals in
+licking themselves take in the young larvæ. These pass out through the
+walls of the Å“sophagus and migrate through the tissues of the animal,
+to finally settle down in the subcutaneous tissue of the back. The
+possibility of their entering directly through the skin, especially in
+case of infestation of man, is not absolutely precluded, although it is
+doubtful.
+
+For both species of _Hypoderma_ there are numerous cases on record of
+their occurrence in man. Hamilton (1893) saw a boy, six years of age,
+who had been suffering for some months from the glands on one side of
+his neck being swollen and from a fetid ulceration around the back teeth
+of the lower jaw of the same side. Three months' treatment was of no
+avail and the end seemed near; one day a white object, which was seen to
+move, was observed in the ulcer at the root of the tongue, and on being
+extracted was recognized as a full grown larva of _Hypoderma_. It was of
+usual tawny color, about half an inch long when contracted, about one
+third that thickness, and quite lively. The case resulted fatally. The
+boy had been on a dairy farm the previous fall, where probably the egg
+(or larva) was in some way taken into his mouth, and the larva found
+between the base of the tongue and the jaw suitable tissue in which to
+develop.
+
+Topsent (1901) reports a case of "creeping myasis" caused by _H.
+lineata_ in the skin of the neck and shoulders of a girl eight years of
+age. The larva travelled a distance of nearly six and a half inches. The
+little patient suffered excruciating pain in the place occupied by the
+larva.
+
+_Hypoderma diana_ infests deer, and has been known to occur in man.
+
+_Oestris ovis_, the sheep bot-fly, or head maggot, is widely distributed
+in all parts of the world. In mid-summer the flies deposit living
+maggots in the nostrils of sheep. These larvæ promptly pass up the nasal
+passages into the frontal and maxillary sinuses, where they feed on the
+mucous to be found there. In their migrations they cause great
+irritation to their host, and when present in numbers may cause vertigo,
+paroxysms, and even death. Portschinsky in an important monograph on
+this species, has discussed in detail its relation to man. He shows that
+it is not uncommon for the fly to attack man and that the minute living
+larvæ are deposited in the eyes, nostrils, lips, or mouth. A typical
+case in which the larvæ were deposited in the eye was described by a
+German oculist Kayser, in 1905. A woman brought her six year old
+daughter to him and said that the day before, about noontime, a flying
+insect struck the eye of the child and that since then she had felt a
+pain which increased towards evening. In the morning the pain ceased but
+the eye was very red. She was examined at about noon, at which time she
+was quiet and felt no pain. She was not sensitive to light, and the only
+thing noticed was a slight congestion and accumulation of secretion in
+the corner of the right eye. A careful examination of the eye disclosed
+small, active, white larvæ that crawled out from the folds of the
+conjunctiva and then back and disappeared. Five of these larvæ were
+removed and although an uncomfortable feeling persisted for a while, the
+eye became normal in about three weeks.
+
+Some of the other recorded cases have not resulted so favorably, for the
+eyesight has been seriously affected or even lost.
+
+According to Edmund and Etienne Sergent (1907), myasis caused by the
+larvæ of _Oestris ovis_ is very common among the shepherds in Algeria.
+The natives say that the fly deposits its larvæ quickly, while on the
+wing, without pause. The greatest pain is caused when these larvæ
+establish themselves in the nasal cavities. They then produce severe
+frontal headaches, making sleep impossible. This is accompanied by
+continuous secretion from the nasal cavities and itching pains in the
+sinuses. If the larvæ happen to get into the mouth, the throat becomes
+inflamed, swallowing is painful, and sometimes vomiting results. The
+diseased condition may last for from three to ten days or in the case of
+nasal infection, longer, but recovery always follows. The natives remove
+the larvæ from the eye mechanically by means of a small rag. When the
+nose is infested, tobacco fumigations are applied, and in case of throat
+infestation gargles of pepper, onion, or garlic extracts are used.
+
+_Rhinœstrus nasalis_, the Russian gad-fly, parasitizes the
+nasopharyngeal region of the horse. According to Portschinsky, it not
+infrequently attacks man and then, in all the known cases deposits its
+larvæ in the eye, only. This is generally done while the person is
+quiet, but not during sleep. The fly strikes without stopping and
+deposits its larva instantaneously. Immediately after, the victim
+experiences lancinating pains which without intermission increase in
+violence. There is an intense conjunctivitis and if the larvæ are not
+removed promptly the envelopes of the eye are gradually destroyed and
+the organ lost.
+
+[Illustration: 81. Larvæ of Dermatobia cyaniventris. After Blanchard.]
+
+[Illustration: 82. Young larva of Dermatobia cyaniventris. After
+Surcouf.]
+
+_Dermatobia cyaniventris_--This fly (fig. 83) is widely distributed
+throughout tropical America, and in its larval stage is well known as a
+parasite of man. The larvæ (figs. 81 and 82) which are known as the "ver
+macaque," "torcel," "ver moyocuil" or by several other local names,
+enter the skin and give rise to a boil-like swelling, open at the top,
+and comparable with the swelling produced by the warble fly larvæ, in
+cattle. They cause itching and occasional excruciating pain. When
+mature, nearly an inch in length, they voluntarily leave their host,
+drop to the ground and complete their development. The adult female is
+about 12 mm. in length. The face is yellow, the frons black with a
+grayish bloom; antennæ yellow, the third segment four times as long as
+the second, the arista pectinate. The thorax is bluish black with
+grayish bloom; the abdomen depressed, brilliant metallescent blue with
+violet tinge. The legs are yellowish, the squamæ and wings brownish.
+
+The different types of larvæ represented in figure 81 were formerly
+supposed to belong to different species but Blanchard regards them as
+merely various stages of the same species. It is only very recently that
+the early stage and the method by which man becomes infested were made
+known.
+
+[Illustration: 83. Dermatobia cyaniventris (×1¾). After
+Manson.]
+
+[Illustration: 84. Mosquito carrying eggs of Dermatobia cyaniventris.
+After Surcouf.]
+
+About 1900, Blanchard observed the presence of packets of large-sized
+eggs under the abdomen of certain mosquitoes from Central America; and
+in 1910, Dr. Moralès, of Costa Rica, declared that the Dermatobia
+deposited its eggs directly under the abdomen of the mosquito and that
+they were thus carried to vertebrates. Dr. Nunez Tovar observed the
+mosquito carriers of the eggs and placing larvæ from this source on
+animals, produced typical tumors and reared the adult flies. It remained
+for Surcouf (1913) to work out the full details. He found that the
+Dermatobia deposits its eggs in packets covered by a very viscid
+substance, on leaves. These become attached to mosquitoes of the species
+_Janthinosoma lutzi_ (fig. 84) which walk over the leaves. The eggs
+which adhere to the abdomen, remain attached and are thus transported.
+The embryo develops, but the young larva (fig. 82) remains in the egg
+until it has opportunity to drop upon a vertebrate fed upon by the
+mosquito.
+
+
+Muscidæ
+
+The following MUSCIDÆ, characterized elsewhere, deserve special mention
+under our present grouping of parasitic species. Other important species
+will be considered as facultative parasites.
+
+_Stomoxys calcitrans_, the stable-fly, or the biting house-fly, is often
+confused with _Musca domestica_ and therefore is discussed especially in
+our consideration of the latter species as an accidental carrier of
+disease. Its possible relation to the spread of infantile paralysis is
+also considered later.
+
+The _tsetse flies_, belonging to the genus _Glossina_, are African
+species of blood-sucking Muscidæ which have attracted much attention
+because of their rôle in transmitting various trypanosome diseases of
+man and animals. They are characterized in Chapter XII and are also
+discussed in connection with the diseases which they convey.
+
+_Chrysomyia macellaria_, (= _Compsomyia_), the "screw worm"-fly is one
+of the most important species of flies directly affecting man, in North
+America. It is not normally parasitic, however, and hence will be
+considered with other facultative parasites in Chapter IV.
+
+[Illustration: 85. Larva of Auchmeromyia luteola. After Graham-Smith.]
+
+[Illustration: 86. Auchmeromyia luteola (×4). After Graham-Smith.]
+
+_Auchmeromyia luteola_, the Congo floor maggot. This is a muscid of
+grewsome habits, which has a wide distribution throughout Africa. The
+fly (fig. 86) deposits its eggs on the ground of the huts of the
+natives. The whitish larvæ (fig. 85) on hatching are slightly flattened
+ventrally, and each segment bears posteriorly three foot-pads
+transversely arranged. At night the larvæ find their way into the low
+beds or couches of the natives and suck their blood. The adult flies do
+not bite man and, as far as known, the larvæ do not play any rôle in the
+transmission of sleeping sickness or other diseases.
+
+This habit of blood-sucking by muscid larvæ is usually referred to as
+peculiar to _Auchmeromyia luteola_ but it should be noted that the larvæ
+of _Protocalliphora_ frequent the nests of birds and feed upon the
+young. Mr. A. F. Coutant has studied especially the life-history and
+habits of _P. azurea_, whose larvæ he found attacking young crows at
+Ithaca, N.Y. He was unable to induce the larvæ to feed on man.
+
+[Illustration: 87. Cordylobia anthropophaga (×3). After Fülleborn.]
+
+[Illustration: 88. Larva of Cordylobia anthropophaga. After Blanchard.]
+
+_Cordylobia anthropophaga_, (_Ochromyia anthropophaga_), or Tumbu-fly
+(fig. 87) is an African species whose larvæ affect man much as do those
+of _Dermatobia cyniventris_, of Central and South America. The larva
+(fig. 88), which is known as "ver du Cayor" because it was first
+observed in Cayor, in Senegambia, develops in the skin of man and of
+various animals, such as dogs, cats, and monkeys. It is about 12 mm. in
+length, and of the form of the larvæ of other muscids. Upon the
+intermediate segments are minute, brownish recurved spines which give to
+the larva its characteristic appearance. The life-history is not
+satisfactorily worked out, but Fuller (1914), after reviewing the
+evidence believes that, as a rule, it deposits its young in the sleeping
+places of man and animals, whether such be a bed, a board, the floor, or
+the bare ground. In the case of babies, the maggots may be deposited on
+the scalp. The minute maggots bore their way painlessly into the skin.
+As many as forty parasites have been found in one individual and one
+author has reported finding more than three hundred in a spaniel puppy.
+Though their attacks are at times extremely painful, it is seldom that
+any serious results follow.
+
+
+THE SIPHONAPTERA OR FLEAS
+
+The SIPHONAPTERA, or fleas (fig. 89) are wingless insects, with highly
+chitinized and laterally compressed bodies. The mouth-parts are formed
+for piercing and sucking. Compound eyes are lacking but some species
+possess ocelli. The metamorphosis is complete.
+
+This group of parasites, concerning which little was known until
+recently, has assumed a very great importance since it was learned that
+fleas are the carriers of bubonic plague. Now over four hundred species
+are known. Of these, several species commonly attack man. The most
+common hominoxious species are _Pulex irritans_, _Xenopsylla cheopis_,
+_Ctenocephalus canis_, _Ctenocephalus felis_, _Ceratophyllus fasciatus_
+and _Dermatophilus penetrans_, but many others will feed readily on
+human blood if occasion arises.
+
+[Illustration: 89. Xenopsylla cheopis, male (×25). After Jordan and
+Rothschild.]
+
+We shall treat in this place of the general biology and habits of the
+hominoxious forms and reserve for the systematic section the discussion
+of the characteristics of the different genera.
+
+The most common fleas infesting houses in the Eastern United States are
+the cosmopolitan dog and cat fleas, _Ctenocephalus canis_ (fig. 90) and
+_C. felis_. Their life cycles will serve as typical. These two species
+have until recently been considered as one, under the name _Pulex
+serraticeps_. See figure 92.
+
+[Illustration: 90. Dog flea (×15). After Howard.]
+
+The eggs are oval, slightly translucent or pearly white, and measure
+about .5 mm. in their long diameter. They are deposited loosely in the
+hairs of the host and readily drop off as the animal moves around.
+Howard found that these eggs hatch in one to two days. The larvæ are
+elongate, legless, white, worm-like creatures. They are exceedingly
+active, and avoid the light in every way possible. They cast their first
+skin in from three to seven days and their second in from three to four
+days. They commenced spinning in from seven to fourteen days after
+hatching and the imago appeared five days later. Thus in summer, at
+Washington, the entire life cycle may be completed in about two weeks.
+(cf. fig. 91, 92).
+
+Strickland's (1914) studies on the biology of the rat flea,
+_Ceratophyllus fasciatus_, have so important a general bearing that we
+shall cite them in considerable detail.
+
+[Illustration: 91. Larva of Xenopsylla cheopis. After Bacot and
+Ridewood.]
+
+He found, to begin with, that there is a marked inherent range in the
+rate of development. Thus, of a batch of seventy-three eggs, all laid in
+the same day and kept together under the same conditions, one hatched in
+ten days; four in eleven days; twenty-five in twelve days; thirty-one in
+thirteen days; ten in fourteen days; one in fifteen days; and one in
+sixteen days. Within these limits the duration of the egg period seems
+to depend mainly on the degree of humidity. The incubation period is
+never abnormally prolonged as in the case of lice, (Warburton) and
+varying conditions of temperature and humidity have practically no
+effect on the percentage of eggs which ultimately hatch.
+
+The same investigator found that the most favorable condition for the
+larva is a low temperature, combined with a high degree of humidity; and
+that the presence of rubbish in which the larva may bury itself is
+essential to its successful development. When larvæ are placed in a
+bottle containing either wood-wool soiled by excrement, or with feathers
+or filter paper covered with dried blood they will thrive readily and
+pupate. They seem to have no choice between dried blood and powdered rat
+feces for food, and also feed readily on flea excrement. They possess
+the curious habit of always devouring their molted skins.
+
+[Illustration: 92. Head and pronotum of (_a_) dog flea; (_b_) of cat
+flea; (_c_) of hen flea. After Rothschild. (_d_) Nycteridiphilus
+(Ischnopsyllus) hexactenus. After Oudemans.]
+
+An important part of Strickland's experiments dealt with the question of
+duration of the pupal stage under the influence of temperature and with
+the longevity and habits of the adult. In October, he placed a batch of
+freshly formed cocoons in a small dish that was kept near a white rat in
+a deep glass jar in the laboratory. Two months later one small and
+feeble flea had emerged, but no more until February, four months after
+the beginning of the experiment. Eight cocoons were then dissected and
+seven more found to contain the imago fully formed but in a resting
+state. The remainder of the batch was then placed at 70° F. for one
+night, near a white rat. The next day all the cocoons were empty and the
+fleas were found on the white rat.
+
+Thus, temperature greatly influences the duration of the pupal period,
+which in _Ceratophyllus fasciatus_ averages seventeen days. Moreover,
+when metamorphosis is complete a low temperature will cause the imago to
+remain within the cocoon.
+
+Sexually mature and ovipositing fleas, he fed at intervals and kept
+alive for two months, when the experiment was discontinued. In the
+presence of rubbish in which they could bury themselves, unfed rat fleas
+were kept alive for many months, whereas in the absence of any such
+substratum they rarely lived a month. In the former case, it was found
+that the length of life is influenced to some degree by the temperature
+and humidity. In an experiment carried out at 70° F. and 45 per cent
+humidity, the fleas did not live for more than four months, while in an
+experiment at 60° F. and 70 per cent humidity they lived for at least
+seventeen months. There was no indication that fleas kept under these
+conditions sucked moisture from surrounding objects, and those kept in
+bell jars, with an extract of flea-rubbish on filter paper, did not live
+any longer than those which were not so supplied.
+
+Curiously enough, although the rat is the normal host of _Ceratophyllus
+fasciatus_, it was found that when given the choice these fleas would
+feed upon man in preference to rats. However, none of the fleas laid
+eggs unless they fed on rat blood.
+
+The experiments of Strickland on copulation and oviposition in the rat
+flea showed that fleas do not copulate until they are sexually mature
+and that, at least in the case of _Ceratophyllus fasciatus_, the
+reproductive organs are imperfectly developed for some time (more than a
+week) after emerging from the pupa. When mature, copulation takes place
+soon after the fleas have fed on their true host--the rat--but not if
+they have fed on a facultative host only, such as man. Copulation is
+always followed by oviposition within a very short time.
+
+The effect of the rat's blood on the female with regard to egg-laying,
+Strickland concludes, is stimulating rather than nutritive, as fleas
+that were without food for many months were observed to lay eggs
+immediately after one feed. Similarly, the male requires the stimulus of
+a meal of rat's blood before it displays any copulatory activity.
+
+Mitzmain (1910) has described in detail the act of biting on man, as
+observed in the squirrel flea, _Ceratophyllus acutus_. "The flea when
+permitted to walk freely on the arm selects a suitable hairy space where
+it ceases abruptly in its locomotion, takes a firm hold with the tarsi,
+projects its proboscis, and prepares to puncture the skin. A puncture is
+drilled by the pricking epipharynx, the saw-tooth mandibles
+supplementing the movement by lacerating the cavity formed. The two
+organs of the rostrum work alternately, the middle piece boring, while
+the two lateral elements execute a sawing movement. The mandibles, owing
+to their basal attachments, are, as is expressed by the advisory
+committee on plague investigations in India (_Journal of Hygiene_, vol.
+6, No. 4, p. 499), 'capable of independent action, sliding up and down
+but maintaining their relative positions and preserving the lumen of the
+aspiratory channel.' The labium doubles back, the V-shaped groove of
+this organ guiding the mandibles on either side."
+
+"The action of the proboscis is executed with a forward movement of the
+head and a lateral and downward thrust of the entire body. As the
+mouth-parts are sharply inserted, the abdomen rises simultaneously. The
+hind and middle legs are elevated, resembling oars. The forelegs are
+doubled under the thorax, the tibia and tarsi resting firmly on the
+epidermis serve as a support for the body during the feeding. The
+maxillary palpi are retracted beneath the head and thorax. The labium
+continues to bend, at first acting as a sheath for the sawing mandibles,
+and as these are more deeply inserted, it bends beneath the head with
+the elasticity of a bow, forcing the mandibles into the wound until the
+maxillæ are embedded in the skin of the victim. When the proboscis is
+fully inserted, the abdomen ceases for a time its lateral swinging."
+
+"The acute pain of biting is first felt when the mandibles have not
+quite penetrated and subsequently during each distinct movement of the
+abdomen. The swinging of the abdomen gradually ceases as it becomes
+filled with blood. The sting of the biting gradually becomes duller and
+less sensitive as feeding progresses. The movements of the elevated
+abdomen grow noticeably feebler as the downward thrusts of the springy
+bow-like labium becomes less frequent."
+
+"As the feeding process advances one can discern through the translucent
+walls of the abdomen a constant flow of blood, caudally from the
+pharynx, accompanied by a peristaltic movement. The end of the meal is
+signified in an abrupt manner. The flea shakes its entire body, and
+gradually withdraws its proboscis by lowering the abdomen and legs and
+violently twisting the head."
+
+"When starved for several days the feeding of the rat fleas is conducted
+in a rather vigorous manner. As soon as the proboscis is buried to the
+full length the abdomen is raised and there ensues a gradual lateral
+swaying motion, increasing the altitude of the raised end of the abdomen
+until it assumes the perpendicular. The flea is observed at this point
+to gain a better foothold by advancing the fore tarsi, and then,
+gradually doubling back the abdomen, it turns with extreme agility,
+nearly touching with its dorsal side the skin of the hand upon which it
+is feeding. Meanwhile, the hungry parasite feeds ravenously."
+
+"It is interesting to note the peculiar nervous action which the rodent
+fleas exhibit immediately when the feeding process is completed or when
+disturbed during the biting. Even while the rostrum is inserted to the
+fullest the parasite shakes its head spasmodically; in a twinkling the
+mouth is withdrawn and then the flea hops away."
+
+A habit of fleas which we shall see is of significance in considering
+their agency in the spread of bubonic plague, is that of ejecting blood
+from the anus as they feed.
+
+Fleas are famous for their jumping powers, and in control measures it is
+of importance to determine their ability along this line. It is often
+stated that they can jump about four inches, or, according to the Indian
+Plague Commission _Xenopsylla cheopis_ cannot hop farther than five
+inches. Mitzmain (1910) conducted some careful experiments in which he
+found that the human flea, _Pulex irritans_, was able to jump as far as
+thirteen inches on a horizontal plane. The mean average of five
+specimens permitted to jump at will was seven and three-tenths inches.
+The same species was observed to jump perpendicularly to a height of at
+least seven and three-fourths inches. Other species were not able to
+equal this record.
+
+The effect of the bite of fleas on man varies considerably according to
+the individual susceptibility. According to Patton and Cragg, this was
+borne out in a curious manner by the experiments of Chick and Martin.
+"In these, eight human hosts were tried; in seven, little or no
+irritation was produced, while in one quite severe inflammation was set
+up around each bite." Of two individuals, equally accustomed to the
+insects, going into an infested room, one may be literally tormented by
+them while the other will not notice them. Indeed it is not altogether
+a question of susceptibility, for fleas seem to have a special
+predilection for certain individuals. The typical itching wheals
+produced by the bites are sometimes followed, especially after
+scratching, by inflammatory papules.
+
+The itching can be relieved by the use of lotions of carbolic acid (2-3
+per cent), camphor, menthol lotion, or carbolated vaseline. If forced to
+sleep in an infested room, protection from attacks can be in a large
+measure gained by sprinkling pyrethrum, bubach, or California insect
+powder between the sheets. The use of camphor, menthol, or oil of
+eucalyptus, or oil of pennyroyal is also said to afford protection to a
+certain extent.
+
+In the Eastern United States the occurrence of fleas as household pests
+is usually due to infested cats and dogs which have the run of the
+house. We have seen that the eggs are not attached to the host but drop
+to the floor when they are laid. Verrill, cited by Osborn, states that
+on one occasion he was able to collect fully a teaspoonful of eggs from
+the dress of a lady in whose lap a half-grown kitten had been held for a
+short time. Patton and Cragg record seeing the inside of a hat in which
+a kitten had spent the night, so covered with flea eggs that it looked
+"as if it had been sprinkled with sugar from a sifter." It is no wonder
+that houses in which pets live become overrun with the fleas.
+
+One of the first control measures, then, consists in keeping such
+animals out of the house or in rigorously keeping them free from fleas.
+The latter can best be accomplished by the use of strong tar soap or
+Armour's "Flesope," which may be obtained from most druggists. The use
+of a three per cent solution of creolin, approximately four teaspoonfuls
+to a quart of warm water, has also been recommended. While this is
+satisfactory in the case of dogs, it is liable to sicken cats, who will
+lick their fur in an effort to dry themselves. Howard recommends
+thoroughly rubbing into the fur a quantity of pyrethrum powder. This
+partially stupifies the fleas which should be promptly swept up and
+burned.
+
+He also recommends providing a rug for the dog or cat to sleep on and
+giving this rug a frequent shaking and brushing, afterwards sweeping up
+and burning the dust thus removed.
+
+Since the larvæ of fleas are very susceptible to exposure, the use of
+bare floors, with few rugs, instead of carpets or matting, is to be
+recommended. Thorough sweeping, so as to allow no accumulation of dust
+in cracks and crevices will prove efficient. If a house is once
+infested it may be necessary to thoroughly scrub the floors with hot
+soapsuds, or to spray them with gasoline. If the latter method is
+adopted, care must be taken to avoid the possibility of fire.
+
+To clear a house of fleas Skinner recommends the use of flake
+naphthalene. In a badly infested house he took one room at a time,
+scattering on the floor five pounds of flake naphthalene, and closed it
+for twenty-four hours. It proved to be a perfect and effectual remedy
+and very inexpensive, as the naphthalene could be swept up and
+transferred to other rooms. Dr. Skinner adds, "so far as I am concerned,
+the flea question is solved and if I have further trouble I know the
+remedy. I intend to keep the dog and cat."
+
+The late Professor Slingerland very effectively used hydrocyanic acid
+gas fumigation in exterminating fleas in houses. In one case, where
+failure was reported, he found on investigation that the house had
+become thoroughly reinfested from pet cats, which had been left
+untreated. Fumigation with sulphur is likewise efficient.
+
+The fact that adult fleas are usually to be found on the floor, when not
+on their hosts, was ingeniously taken advantage of by Professor S. H.
+Gage in ridding an animal room at Cornell University of the pests. He
+swathed the legs of a janitor with sticky fly-paper and had him walk
+back and forth in the room. Large numbers of the fleas were collected in
+this manner.
+
+In some parts of the southern United States hogs are commonly infested
+and in turn infest sheds, barns and even houses. Mr. H. E. Vick informs
+us that it is a common practice to turn sheep into barn-lots and sheds
+in the spring of the year to collect in their wool, the fleas which
+abound in these places after the hogs have been turned out.
+
+It is a common belief that adult fleas are attracted to fresh meat and
+that advantage of this can be taken in trapping them. Various workers,
+notably Mitzman (1910), have shown that there is no basis for such a
+belief.
+
+
+THE TRUE CHIGGERS--The chigoes, or true chiggers, are the most
+completely parasitic of any of the fleas. Of the dozen or more known
+species, one commonly attacks man. This is _Dermatophilus penetrans_,
+more commonly known as _Sarcopsylla penetrans_ or _Pulex penetrans_.
+
+This species occurs in Mexico, the West Indies, Central and South
+America. There are no authentic records of its occurrence in the United
+States although, as Baker has pointed out, there is no reason why it
+should not become established in Florida and Texas. It is usually
+believed that Brazil was its original home. Sometime about the middle of
+the nineteenth century it was introduced into West Africa and has spread
+across that continent.
+
+The males and the immature females of _Dermatophilus penetrans_ (fig.
+93) closely resemble those of other fleas. They are very active little
+brown insects about 1-1.2 mm. in size, which live in the dust of native
+huts and stables, and in dry, sandy soil. In such places they often
+occur in enormous numbers and become a veritable plague.
+
+[Illustration: 93. Dermatophilus penetrans. Much enlarged. After
+Karsten.]
+
+They attack not only man but various animals. According to Castellani
+and Chalmers, "Perhaps the most noted feature is the way in which it
+attacks pigs. On the Gold Coast it appeared to be largely kept in
+existence by these animals. It is very easily captured in the free state
+by taking a little pig with a pale abdomen, and placing it on its back
+on the ground on which infected pigs are living. After watching a few
+moments, a black speck will appear on the pig's abdomen, and quickly
+another and another. These black specks are jiggers which can easily be
+transferred to a test tube. On examination they will be found to be
+males and females in about equal numbers."
+
+Both the males and females suck blood. That which characterizes this
+species as distinguished from other fleas attacking man is that when the
+impregnated female attacks she burrows into the skin and there swells
+until in a few days she has the size and appearance of a small pea (fig.
+94). Where they are abundant, hundreds of the pests may attack a single
+individual (fig. 95). Here they lie with the apex of the abdomen
+blocking the opening. According to Fülleborn (1908) they do not
+penetrate beneath the epidermis. The eggs are not laid in the flesh of
+the victim, as is sometimes stated, but are expelled through this
+opening. The female then dies, withers and falls away or is expelled by
+ulceration. According to Brumpt, she first quits the skin and then,
+falling to the ground, deposits her eggs. The subsequent development in
+so far as known, is like that of other fleas.
+
+[Illustration: 94. Dermatophilus penetrans, gravid female. After
+Moniez.]
+
+[Illustration: 95. Chiggers in the sole of foot of man. Manson's
+Tropical Diseases. Permission of Cassell and Co.]
+
+The chigoe usually enters between the toes, the skin about the roots of
+the nails, or the soles of the feet, although it may attack other parts
+of the body. Mense records the occurrence in folds of the epidermis, as
+in the neighborhood of the anus. They give rise to irritation and unless
+promptly and aseptically removed there often occurs pus formation and
+the development of a more or less serious abscess. Gangrene and even
+tetanus may ensue.
+
+Treatment consists in the careful removal of the insect, an operation
+more easily accomplished a day or two after its entrance, than at first,
+when it is unswollen. The ulcerated point should then be treated with
+weak carbolic acid, or tincture of iodine, or dusted thoroughly with an
+antiseptic powder.
+
+[Illustration: 96. Echidnophaga gallinacea.]
+
+[Illustration: 97. Echidnophaga gallinacea infesting head of chicken.
+After Enderlein.]
+
+Castellani and Chalmers recommend as prophylactic measures, keeping the
+house clean and keeping pigs, poultry, and cattle away therefrom. "High
+boots should be used, and especial care should be taken not to go to a
+ground floor bathroom with bare feet. The feet, especially the toes, and
+under the nails, should be carefully examined every morning to see if
+any black dots can be discovered, when the jigger should be at once
+removed, and in this way suppuration will be prevented. It is
+advisable, also, to sprinkle the floors with carbolic lotion, Jeyes'
+fluid, or with pyrethrum powder, or with a strong infusion of native
+tobacco, as recommended by Law and Castellani."
+
+_Echidnophaga gallinacea_ (fig. 96) is a widely distributed Hectopsyllid
+attacking poultry (fig. 97). It occurs in the Southern and Southwestern
+United States and has been occasionally reported as attacking man,
+especially children. It is less highly specialized than _Dermatophilus
+penetrans_, and does not ordinarily cause serious trouble in man.
+
+
+
+
+CHAPTER IV
+
+ACCIDENTAL OR FACULTATIVE PARASITES
+
+
+In addition to the many species of Arthropods which are normally
+parasitic on man and animals, there is a considerable number of those
+which may be classed as _accidental_ or _facultative_ parasites.
+
+Accidental or facultative parasites are species which are normally
+free-living, but which are able to exist as parasites when accidentally
+introduced into the body of man or other animal. A wide range of forms
+is included under this grouping.
+
+
+ACARINA
+
+A considerable number of mites have been reported as accidental or even
+normal, endoparasites of man, but the authentic cases are comparatively
+few.
+
+In considering such reports it is well to keep in mind von Siebold's
+warning that in view of the universal distribution of mites one should
+be on his guard. In vessels in which animal and other organic fluids and
+moist substances gradually dry out, mites are very abundantly found. If
+such vessels are used without very careful preliminary cleaning, for the
+reception of evacuations of the sick, or for the reception of parts
+removed from the body, such things may be readily contaminated by mites,
+which have no other relation whatever to them.
+
+Nevertheless, there is no doubt but that certain mites, normally
+free-living, have occurred as accidental parasites of man. Of these the
+most commonly met with is _Tyroglyphus siro_, the cheese-mite.
+
+_Tyroglyphus siro_ is a small mite of a whitish color. The male measures
+about 500µ long by 250µ wide, the female slightly larger. They live in
+cheese of almost any kind, especially such as is a little decayed. "The
+individuals gather together in winter in groups or heaps in the hollows
+and chinks of the cheese and there remain motionless. As soon as the
+temperature rises a little, they gnaw away at the cheese and reduce it
+to a powder. The powder is composed of excrement having the appearance
+of little grayish microscopic balls; eggs, old and new, cracked and
+empty; larvæ, nymphs, and perfect mites, cast skins and fragments of
+cheese, to which must be added numerous spores of microscopic
+fungi."--Murray.
+
+_Tyroglyphus siro_, and related species, have been found many times in
+human feces, under conditions which preclude the explanation that the
+contamination occurred outside of the body. They have been supposed to
+be the cause of dysentery, or diarrhœa, and it is probable that the
+_Acarus dysenteriæ_ of Linnæus, and Latreille, was this species.
+However, there is little evidence that the mites cause any noteworthy
+symptoms, even when taken into the body in large numbers.
+
+_Histiogaster spermaticus_ (fig. 152) is a Tyroglyphid mite which was
+reported by Trouessart (1902) as having been found in a cyst in the
+groin, adherent to the testis. When the cyst was punctured, it yielded
+about two ounces of opalescent fluid containing spermatozoa and numerous
+mites in all stages of development. The evidence indicated that a
+fecundated female mite had been introduced into the urethra by means of
+an unclean catheter. Though Trouessart reported the case as that of a
+Sarcoptid, Banks places the genus _Histiogaster_ with the Tyroglyphidæ.
+He states that our species feeds on the oyster-shell bark louse,
+possibly only after the latter is dead, and that in England a species
+feeds within decaying reeds.
+
+_Nephrophages sanguinarius_ is a peculiarly-shaped, angular mite which
+was found by Miyake and Scriba (1893) for eight successive days in the
+urine of a Japanese suffering from fibrinuria. Males, .117 mm. long by
+.079 mm. wide, females .36 mm. by. 12 mm., and eggs were found both in
+the spontaneously emitted urine and in that drawn by means of a
+catheter. All the mites found were dead. The describers regarded this
+mite as a true endoparasite, but it is more probable that it should be
+classed as an accidental parasite.
+
+
+MYRIAPODA
+
+There are on record a number of cases of myriapods occurring as
+accidental parasites of man. The subject has been treated in detail by
+Blanchard (1898 and 1902), who discussed forty cases. Since then at
+least eight additions have been made to the list.
+
+Neveau-Lamaire (1908) lists thirteen species implicated, representing
+eight different genera. Of the _Chilognatha_ there are three, _Julus
+terrestris_, _J. londinensis_ and _Polydesmus complanatus_. The
+remainder are _Chilopoda_, namely, _Lithobius forficatus_, _L.
+malenops_, _Geophilus carpophagus_, _G. electricus_, _G. similis_, _G.
+cephalicus_, _Scutigera coleoptrata_, _Himantarium gervaisi_,
+_Chætechelyne vesuviana_ and _Stigmatogaster subterraneus_.
+
+The majority of the cases relate to infestation of the nasal fossæ, or
+the frontal sinus, but intestinal infestation also occurs and there is
+one recorded case of the presence of a species in _Julus_ (fig. 13) in
+the auditory canal of a child.
+
+In the nose, the myriapods have been known to live for months and
+according to some records, even for years. The symptoms caused by their
+presence are inflammation, with or without increased flow of mucus,
+itching, more or less intense headache, and at times general symptoms
+such as vertigo, delirium, convulsions, and the like. These symptoms
+disappear suddenly when the parasites are expelled.
+
+In the intestine of man, myriapods give rise to obscure symptoms
+suggestive of infestation by parasitic worms. In a case reported by
+Verdun and Bruyant (1912), a child twenty months of age had been
+affected for fifteen days by digestive disturbances characterized by
+loss of appetite, nausea and vomiting. The latter had been particularly
+pronounced for three days, when there was discovered in the midst of the
+material expelled a living myriapod of the species _Chætechelyne
+vesuviana_. Anthelminthics had been administered without result. In some
+of the other cases, the administration of such drugs had resulted in the
+expulsion of the parasite through the anus.
+
+One of the extreme cases on record is that reported by Shipley (1914).
+Specimens of _Geophilus gorizensis_ (= _G. subterraneus_) "were vomited
+and passed by a woman of 68 years of age. Some of the centipedes emerged
+through the patient's nose, and it must be mentioned that she was also
+suffering from a round worm. One of her doctors was of the opinion that
+the centipedes were certainly breeding inside the lady's intestines, and
+as many as seven or eight, sometimes more, were daily leaving the
+alimentary canal."
+
+"According to her attendant's statements those centipedes had left the
+body in some hundreds during a period of twelve or eighteen months.
+Their presence produced vomiting and some hæmatemesis, and treatment
+with thymol, male-fern and turpentine had no effect in removing the
+creatures."
+
+The clinical details, as supplied by Dr. Theodore Thompson were as
+follows:
+
+"Examined by me July, 1912, her tongue was dry and glazed. There was
+bleeding taking place from the nose and I saw a living centipede she had
+just extracted from her nostril. Her heart, lungs and abdomen appeared
+normal. She was not very wasted, and did not think she had lost much
+flesh, nor was there any marked degree of anemia."
+
+Shipley gives the following reasons for believing it impossible that
+these centipedes could have multiplied in the patient's intestine. "The
+breeding habits of the genus _Geophilus_ are peculiar, and ill adapted
+for reproducing in such a habitat. The male builds a small web or nest,
+in which he places his sperm, and the female fertilizes herself from
+this nest or web, and when the eggs are fertilized they are again laid
+in a nest or web in which they incubate and in two or three weeks hatch
+out. The young _Geophilus_ differ but very little from the adult, except
+in size. It is just possible, but improbable, that a clutch of eggs had
+been swallowed by the host when eating some vegetables or fruit, but
+against this is the fact that the _Geophilus_ does not lay its eggs upon
+vegetables or fruit, but upon dry wood or earth. The egg-shell is very
+tough and if the eggs had been swallowed the egg-shells could certainly
+have been detected if the dejecta were examined. The specimens of the
+centipede showed very little signs of being digested, and it is almost
+impossible to reconcile the story of the patient with what one knows of
+the habits of the centipedes."
+
+In none of the observed cases have there been any clear indications as
+to the manner of infestation. It is possible that the myriapods have
+been taken up in uncooked fruit or vegetables.
+
+
+LEPIDOPTEROUS LARVÆ
+
+SCHOLECIASIS--Hope (1837) brought together six records of infestation of
+man by lepidopterous larvæ and proposed to apply the name scholeciasis
+to this type of parasitism. The clearest case was that of a young boy
+who had repeatedly eaten raw cabbage and who vomited larvæ of the
+cabbage butterfly, _Pieris brassicæ_. Such cases are extremely rare, and
+there are few reliable data relative to the subject. In this connection
+it may be noted that Spuler (1906) has described a moth whose larvæ live
+as ectoparasites of the sloth.
+
+
+COLEOPTERA
+
+CANTHARIASIS--By this term Hope designated instances of accidental
+parasitism by the larvæ or adults of beetles. Reports of such cases are
+usually scouted by parasitologists but there seems no good basis for
+wholly rejecting them. Cobbold refers to a half dozen cases of
+accidental parasitism by the larvæ of _Blaps mortisaga_. In one of
+these cases upwards of 1200 larvæ and several perfect insects were said
+to have been passed _per annum_. French (1905) reports the case of a man
+who for a considerable period voided adult living beetles of the species
+_Nitidula bipustulata_. Most of the other cases on record relate to the
+larvæ of _Dermestidæ_ (larder beetles _et al._) or _Tenebrionidæ_ (meal
+infesting species). Infestation probably occurs through eating raw or
+imperfectly cooked foods containing eggs or minute larvæ of these
+insects.
+
+[Illustration: 98. Larva of Piophila casei. Caudal aspect of larva.
+Posterior stigmata.]
+
+Brumpt cites a curious case of accidental parasitism by a coleopterous
+larva belonging to the genus _Necrobia_. This larva was extracted from a
+small tumor, several millimeters long, on the surface of the conjunctiva
+of the eye. The larvæ of this genus ordinarily live in decomposing flesh
+and cadavers.
+
+
+DIPTEROUS LARVÆ
+
+[Illustration: 99. Piophila casei. After Graham-Smith.]
+
+MYASIS--By this term (spelled also myiasis, and myiosis), is meant
+parasitism by dipterous larvæ. Such parasitism may be normal, as in the
+cases already described under the heading parasitic Diptera, or it may
+be facultative, due to free-living larvæ being accidentally introduced
+into wounds or the body-cavities of man. Of this latter type, there is a
+multitude of cases on record, relating to comparatively few species. The
+literature of the subject, like that relating to facultative parasitism
+in general, is unsatisfactory, for most of the determinations of species
+have been very loose. Indeed, so little has been known regarding the
+characteristics of the larvæ concerned that in many instances they could
+not be exactly determined. Fortunately, several workers have undertaken
+comparative studies along this line. The most comprehensive publication
+is that of Banks (1912), entitled "The structure of certain dipterous
+larvæ, with particular reference to those in human food."
+
+Without attempting an exhaustive list, we shall discuss here the more
+important species of Diptera whose larvæ are known to cause myasis,
+either external or internal. The following key will serve to determine
+those most likely to be encountered. The writers would be glad to
+examine specimens not readily identifiable, if accompanied by exact data
+relative to occurrence.
+
+_a._ Body more or less flattened, depressed; broadest in the middle,
+    each segment with dorsal, lateral, and ventral fleshy processes, of
+    which the laterals, at least, are more or less spiniferous (fig.
+    101). _Fannia_ (= _Homalomyia_).
+
+  In _F. canicularis_ the dorsal processes are nearly as long as the
+      laterals; in _F. scalaris_ the dorsal processes are short spinose
+      tubercles.
+
+_aa._ Body cylindrical, or slender conical tapering toward the head;
+    without fleshy lateral processes (fig. 105).
+
+_b._ With the posterior stigmata at the end of shorter or longer
+    tubercles, or if not placed upon tubercles, then not in pit; usually
+    without a "marginal button" and without a chitinous ring surrounding
+    the three slits; the slits narrowly or broadly oval, not bent (fig.
+    171 i). _Acalyptrate muscidæ_ and some species of _Anthomyiidæ_. To
+    this group belong the cheese skipper (_Piophila casei_, figs. 98,
+    99), the pomace-fly (_Drosophila ampelophila_), the apple maggot
+    (_Rhagoletis pomonella_), the cherry fruit fly (_Rhagoletis
+    cingulata_), the small dung fly (_Sepsis violacea_, fig. 170), the
+    beet leaf-miner (_Pegomyia vicina_, fig. 171 i), the cabbage, bean
+    and onion maggots (_Phorbia_ spp.) et. al.
+
+_bb._ Posterior stigmata of various forms, if the slits are narrowly
+    oval (fig. 171) then they are surrounded by a chitin ring which may
+    be open ventro-mesally.
+
+_c._ Integument leathery and usually strongly spinulose; larvæ
+    hypodermatic or endoparasitic. Bot flies (fig. 171, f, g,
+    k).--_Oestridæ_
+
+_cc._ Integument not leathery and (except in _Protocalliphora_) spinulæ
+    restricted to transverse patches near the incisures of the segments.
+
+_d._ The stigmal plates in a pit; the lip-like margin of the pit with a
+    number of fleshy tubercles; chitin ring of the stigma not complete;
+    open ventro-mesally, button absent (fig. 171 e). Flesh
+    flies.--_Sarcophaga_
+
+_dd._ Stigmata not in a pit.
+
+_e._ The chitin ring open ventra-mesally; button absent (fig. 171 c).
+    Screw-worm fly. _Chrysomyia_
+
+_ee._ The chitin ring closed.
+
+_f._ Slits of the posterior stigmata straight; marginal "button" present
+    (fig. 171 b); two distinct mouth hooks, fleshy tubercles around the
+    anal area. _Phormia_ (fig. 171 f), _Lucilia_ and _Calliphora_ (fig.
+    172, a, b), _Protocalliphora_ (fig. 171, j), _Cynomyia_ (fig. 171,
+    a). Blow flies, bluebottle flies. _Calliphorinæ_
+
+_ff._ Slits of the posterior stigmata sinuous or bent. Subfamily
+    Muscinæ.
+
+_g._ Slits of the posterior stigmata bent; usually two mouth hooks.
+    _Muscina stabulans_ (fig. 171, l), _Muscina similis_, _Myiospila
+    meditabunda_ (fig. 172, i), and some of the higher _Anthomyiidæ_.
+
+_gg._ Slits of the posterior stigmata sinuous; mouth hooks usually
+    consolidated into one. The house-fly (_Musca domestica_ fig. 171,
+    d), the stable fly (_Stomoxys calcitrans_), the horn fly (_Lyperosia
+    irritans_), _Pyrellia_, _Pseudopyrellia_, _Morellia_, _Mesembrina_.
+    _Polietes_, et. al. (fig. 172 in part).
+
+_Eristalis_--The larvæ of _Eristalis_ are the so-called rat-tailed
+maggots, which develop in foul water. In a few instances these larvæ
+have been known to pass through the human alimentary canal uninjured.
+Hall and Muir (1913) report the case of a boy five years of age, who had
+been ailing for ten weeks and who was under treatment for indigestion
+and chronic constipation. For some time he had vomited everything he
+ate. On administration of a vermifuge he voided one of the rat-tailed
+maggots of _Eristalis_. He admitted having drunk water from a ditch full
+of all manner of rotting matter. It was doubtless through this that he
+became infested. It is worth noting that the above described symptoms
+may have been due to other organisms or substances in the filthy water.
+
+_Piophila casei_, the cheese-fly (fig. 99), deposits its eggs not only
+in old cheeses, but on ham, bacon, and other fats. The larvæ (fig. 98)
+are the well-known cheese skippers, which sometimes occur in great
+abundance on certain kinds of cheese. Indeed, some people have a
+comfortable theory that such infested cheese is especially good. Such
+being the case, it is small wonder that this species has been repeatedly
+reported as causing intestinal myasis. Thebault (1901) describes the
+case of a girl who, shortly after consuming a large piece of badly
+infested cheese, became ill and experienced severe pains in the region
+of the navel. Later these extended through the entire alimentary canal,
+the excrement was mixed with blood and she suffered from vertigo and
+severe headaches. During the four following days the girl felt no
+change, although the excretion of the blood gradually diminished and
+stopped. On the fourth day she voided two half-digested larvæ and,
+later, seven or eight, of which two were alive and moving.
+
+That these symptoms may be directly attributed to the larvæ, or
+"skippers," has been abundantly shown by experimental evidence.
+Portschinsky cites the case of a dog fed on cheese containing the larvæ.
+The animal suffered much pain and its excrement contained blood. On
+_post mortem_ it was found that the small intestine throughout almost
+its entire length was marked by bloody bruises. The papillæ on these
+places were destroyed, although the walls were not entirely perforated.
+In the appendix were found two or three dead larvæ. Alessandri (1910)
+has likewise shown that the larvæ cause intestinal lesions.
+
+According to Graham-Smith, Austen (1912) has recorded a case of myasis
+of the nose, attended with a profuse watery discharge of several weeks
+duration and pain, due to the larvæ of _Piophila casei_.
+
+
+ANTHYOMYIIDÆ--The characteristic larvæ of two species of _Fannia_ (=
+_Homalomyia_ or _Anthomyia_, in part) (fig. 101) are the most commonly
+reported of dipterous larvæ causing intestinal myasis. Hewitt (1912) has
+presented a valuable study of the bionomics and of the larvæ of these
+flies, a type of what is needed for all the species concerned in myasis.
+We have seen two cases of their having been passed in stools, without
+having caused any special symptoms. In other instances their presence in
+the alimentary canal has given rise to symptoms vaguely described as
+those of tapeworm infestation, or helminthiasis. More specifically, they
+have been described as causing vertigo, severe headache, nausea and
+vomiting, severe abdominal pains, and in some instances, bloody
+diarrhœa.
+
+[Illustration: 100. Fannia canicularis (×4). After Graham-Smith.]
+
+One of the most striking cases is that reported by Blankmeyer (1914), of
+a woman whose illness began fourteen years previously with nausea and
+vomiting. After several months of illness she began passing larvæ and
+was compelled to resort to enemas. Three years previous to the report,
+she noticed frequent shooting pains in the rectal region and at times
+abdominal tenderness was marked. There was much mucus in the stools and
+she "experienced the sensation of larvæ crawling in the intestine."
+Occipital headaches were marked, with remissions, and constipation
+became chronic. The appetite was variable, there was a bad taste in the
+mouth, tongue furred and ridged, and red at the edges. Her complexion
+was sallow, and general nervousness was marked. As treatment, there were
+given doses of magnesium sulphate before breakfast and at 4 P. M., with
+five grain doses of salol four times a day. The customary parasiticides
+yielded no marked benefit. At the time of the report the patient passed
+from four to fifty larvæ per day, and was showing some signs of
+improvement. The nausea had disappeared, her nervousness was less
+evident, and there was a slight gain in weight.
+
+The case was complicated by various other disorders, but the symptoms
+given above seem to be in large part attributable to the myasis. There
+is nothing in the case to justify the assumption that larvæ were
+continuously present, for years. It seems more reasonable to suppose
+that something in the habits of the patient favored repeated
+infestation. Nevertheless, a study of the various cases of intestinal
+myasis caused by these and other species of dipterous larvæ seems to
+indicate that the normal life cycle may be considerably prolonged under
+the unusual conditions.
+
+The best authenticated cases of myasis of the urinary passage have been
+due to larvæ of _Fannia_. Chevril (1909) collected and described twenty
+cases, of which seven seemed beyond doubt. One of these was that of a
+woman of fifty-five who suffered from albuminuria, and urinated with
+much difficulty, and finally passed thirty to forty larvæ of _Fannia
+canicularis_.
+
+It is probable that infestation usually occurs through eating partially
+decayed fruit or vegetables on which the flies have deposited their
+eggs. Wellman points out that the flies may deposit their eggs in or
+about the anus of persons using outside privies and Hewitt believes that
+this latter method of infection is probably the common one in the case
+of infants belonging to careless mothers. "Such infants are sometimes
+left about in an exposed and not very clean condition, in consequence of
+which flies are readily attracted to them and deposit their eggs."
+
+[Illustration: 101. Larva of Fannia scalaris.]
+
+
+MUSCINÆ--The larvæ of the common house-fly, _Musca domestica_, are
+occasionally recorded as having been passed with the feces or vomit of
+man. While such cases may occur, it is probable that in most instances
+similar appearing larvæ of other insects have been mistakenly
+identified.
+
+_Muscina stabulans_ is regarded by Portschinsky (1913) as responsible
+for many of the cases of intestinal myasis attributed to other species.
+He records the case of a peasant who suffered from pains in the lower
+part of the breast and intestines, and whose stools were mixed with
+blood. From November until March he had felt particularly ill, being
+troubled with nausea and vomiting in addition to the pain in his
+intestines. In March, his physician prescribed injections of a
+concentrated solution of tannin, which resulted in the expulsion of
+fifty living larvæ of _Muscina stabulans_. Thereafter the patient felt
+much better, although he suffered from intestinal catarrh in a less
+severe form.
+
+[Illustration: 102 Muscina stabulans (×4). After Graham-Smith.]
+
+
+CALLIPHORINÆ--Closely related to the Sarcophagidæ are the
+_Calliphorinæ_, to which group belong many of the so-called "blue
+bottle" flies. Their larvæ feed upon dead animals, and upon fresh and
+cooked meat. Those of _Protocalliphora_, already mentioned, are
+ectoparasitic on living nestling birds. Larva of _Lucilia_, we have
+taken from tumors on living turtles. To this sub-family belongs also
+_Aucheromyia luteola_, the Congo floor maggot. Some of these, and at
+least the last mentioned, are confirmed, rather than faculative
+parasites. Various species of Calliphorinæ are occasionally met with as
+facultative parasites of man.
+
+[Illustration: 103. Lucilia cæsar, (×3). After Howard.]
+
+_Chrysomyia macellaria_, the screw worm fly (fig. 107), is the fly which
+is responsible for the most serious cases of human myasis in the United
+States. It is widely distributed in the United States but is especially
+abundant in the south. While the larvæ breed in decaying matter in
+general, they so commonly breed in the living flesh of animals that they
+merit rank as true parasites. The females are attracted to open wounds
+of all kinds on cattle and other animals and quickly deposit large
+numbers of eggs. Animals which have been recently castrated, dehorned,
+or branded, injured by barbed wire, or even by the attacks of ticks are
+promptly attacked in the regions where the fly abounds. Even the navel
+of young calves or discharges from the vulva of cows may attract the
+insect.
+
+[Illustration: 104. Calliphora erythrocephala, (×6). After
+Graham-Smith.]
+
+Not infrequently the fly attacks man, being attracted by an offensive
+breath, a chronic catarrh, or a purulent discharge from the ears. Most
+common are the cases where the eggs are deposited in the nostrils. The
+larvæ, which are hatched in a day or two, are provided with strong
+spines and proceed to bore into the tissues of the nose, even down into
+or through the bone, into the frontal sinus, the pharynx, larynx, and
+neighboring parts.
+
+Osborn (1896) quotes a number of detailed accounts of the attacks of the
+_Chrysomyia_ on man. A vivid picture of the symptomology of rhinal
+myasis caused by the larvæ of this fly is given by Castellani and
+Chalmers: "Some couple of days after a person suffering from a chronic
+catarrh, foul breath, or ozæna, has slept in the open or has been
+attacked by a fly when riding or driving,--_i.e._, when the hands are
+engaged--signs of severe catarrh appear, accompanied with inordinate
+sneezing and severe pain over the root of the nose or the frontal bone.
+Quickly the nose becomes swollen, and later the face also may swell,
+while examination of the nose may show the presence of the larvæ. Left
+untreated, the patient rapidly becomes worse, and pus and blood are
+discharged from the nose, from which an offensive odor issues. Cough
+appears as well as fever, and often some delirium. If the patient lives
+long enough, the septum of the nose may fall in, the soft and hard
+palates may be pierced, the wall of the pharynx may be destroyed. By
+this time, however, the course of the disease will have become quite
+evident by the larvæ dropping out of the nose, and if the patient
+continues to live all the larvæ may come away naturally."
+
+For treatment of rhinal myasis these writers recommend douching the nose
+with chloroform water or a solution of chloroform in sweet milk (10-20
+per cent), followed by douches of mild antiseptics. Surgical treatment
+may be necessary.
+
+[Illustration: 105. Larva of a flesh fly (Sarcophaga). Caudal aspect.
+Anterior stigmata. Pharyngeal skeleton.]
+
+
+SARCOPHAGIDÆ--The larvæ (fig. 105) of flies of this family usually feed
+upon meats, but have been found in cheese, oleomargerine, pickled
+herring, dead and living insects, cow dung and human feces. Certain
+species are parasitic in insects. Higgins (1890) reported an instance of
+"hundreds" of larvæ of _Sarcophaga_ being vomited by a child eighteen
+months of age. There was no doubt as to their origin for they were
+voided while the physician was in the room. There are many other reports
+of their occurrence in the alimentary canal. We have recorded elsewhere
+(Riley, 1906) a case in which some ten or twelve larvæ of _Sarcophaga_
+were found feeding on the diseased tissues of a malignant tumor. The
+tumor, a melanotic sarcoma, was about the size of a small walnut, and
+located in the small of the back of an elderly lady. Although they had
+irritated and caused a slight hæmorrhage, neither the patient nor others
+of the family knew of their presence. Any discomfort which they had
+caused had been attributed to the sarcomatous growth. The infestation
+occurred in mid-summer. It is probable that the adult was attracted by
+the odor of the discharges and deposited the living maggots upon the
+diseased tissues.
+
+[Illustration: 106. A flesh fly (Sarcophaga), (×4). After Graham-Smith.]
+
+According to Küchenmeister, _Sarcophaga carnaria_ (fig. 106), attracted
+by the odor, deposits its eggs and larvæ in the vagina of girls and
+women when they lie naked in hot summer days upon dirty clothes, or when
+they have a discharge from the vagina. In malignant inflammations of the
+eyes the larvæ even nestle under the eyelids and in Egypt, for example,
+produce a very serious addition to the effects of small-pox upon the
+cornea, as according to Pruner, in such cases perforation of the cornea
+usually takes place.
+
+[Illustration: 107. Chrysomyia macellaria, (×3).]
+
+_Wohlfartia magnifica_ is another Sarcophagid which commonly infests man
+in the regions where it is abundant. It is found in all Europe but is
+especially common in Russia, where Portschinsky has devoted much
+attention to its ravages. It deposits living larvæ in wounds, the nasal
+fossæ, the ears and the eyes, causing injuries even more revolting than
+those described for _Chrysomyia_.
+
+
+
+
+CHAPTER V
+
+ARTHROPODS AS SIMPLE CARRIERS OF DISEASE
+
+
+The fact that certain arthropods are poisonous, or may affect the health
+of man as direct parasites has always received attention in the medical
+literature. We come now to the more modern aspect of our subject,--the
+consideration of insects and other arthropods as transmitters and
+disseminators of disease.
+
+The simplest way in which arthropods may function in this capacity is as
+_simple carriers_ of pathogenic organisms. It is conceivable that any
+insect which has access to, and comes in contact with such organisms and
+then passes to the food, or drink, or to the body of man, may in a
+wholly accidental and incidental manner convey infection. That this
+occurs is abundantly proved by the work of recent years. We shall
+consider as typical the case against the house-fly, which has attracted
+so much attention, both popular and scientific. The excellent general
+treatises of Hewitt (1910), Howard (1911), and Graham-Smith (1913), and
+the flood of bulletins and popular literature render it unnecessary to
+consider the topic in any great detail.
+
+
+THE HOUSE-FLY AS A CARRIER OF DISEASE
+
+Up to the past decade the house-fly has usually been regarded as a mere
+pest. Repeatedly, however, it had been suggested that it might
+disseminate disease. We have seen that as far back as the sixteenth
+century, Mercurialis suggested that it was the agent in the spread of
+bubonic plague, and in 1658, Kircher reiterated this view. In 1871,
+Leidy expressed the opinion that flies were probably a means of
+communicating contagious diseases to a greater degree than was generally
+suspected. From what he had observed regarding gangrene in hospitals, he
+thought flies should be carefully excluded from wounds. In the same
+year, the editor of the _London Lancet_, referring to the belief that
+they play a useful rôle in purifying the air said, "Far from looking
+upon them as dipterous angels dancing attendance on Hygeia, regard them
+rather in the light of winged sponges spreading hither and thither to
+carry out the foul behests of Contagion."
+
+These suggestions attracted little attention from medical men, for it is
+only within very recent years that the charges have been supported by
+direct evidence. Before considering this evidence, it is necessary that
+we define what is meant by "house-fly" and that we then consider the
+life-history of the insect.
+
+There are many flies which are occasionally to be found in houses, but
+according to various counts, from 95 per cent to 99 per cent of these in
+warm weather in the Eastern United States belong to the one species
+_Musca domestica_ (fig. 108). This is the dominant house-fly the world
+over and is the one which merits the name. It has been well
+characterized by Schiner (1864), whose description has been freely
+translated by Hewitt, as follows:
+
+"Frons of male occupying a fourth part of the breadth of the head.
+Frontal stripe of female narrow in front, so broad behind that it
+entirely fills up the width of the frons. The dorsal region of the
+thorax dusty grey in color with four equally broad longitudinal stripes.
+Scutellum gray with black sides. The light regions of the abdomen
+yellowish, transparent, the darkest parts at least at the base of the
+ventral side yellow. The last segment and a dorsal line blackish brown.
+Seen from behind and against the light, the whole abdomen shimmering
+yellow, and only on each side of the dorsal line on each segment a dull
+transverse band. The lower part of the face silky yellow, shot with
+blackish brown. Median stripe velvety black. Antennæ brown. Palpi black.
+Legs blackish brown. Wings tinged with pale gray with yellowish base.
+The female has a broad velvety back, often reddishly shimmering frontal
+stripe, which is not broader at the anterior end than at the bases of
+the antennæ, but become so very much broader above that the light
+dustiness of the sides is entirely obliterated. The abdomen gradually
+becoming darker. The shimmering areas on the separate segments generally
+brownish. All the other parts are the same as in the male."
+
+The other species of flies found in houses in the Eastern United States
+which are frequently mistaken for the house or typhoid fly may readily
+be distinguished by the characters of the following key:
+
+_a._ Apical cell (R_5) of the wide wing open, i.e., the bounding veins
+    parallel or divergent (fig. 100). Their larvæ are flattened, the
+    intermediate body segments each fringed with fleshy, more or less
+    spinose, processes. _Fannia_
+
+  b. Male with the sides of the second and third abdominal segments
+      translucent yellowish. The larva with three pairs of nearly equal
+      spiniferous appendages on each segment, arranged in a
+      longitudinal series and in addition two pairs of series of smaller
+      processes (fig. 100) _F. canicularis_
+
+  bb. Male with blackish abdomen, middle tibia with a tubercle beyond
+      the middle. The larva with spiniferous appendages of which the
+      dorsal and ventral series are short, the lateral series long and
+      feathered (fig. 101) _F. scalaris_
+
+aa. Apical cell (R) of the wing more or less narrowed in the margin; i.
+    e., the bounding veins more or less converging (fig. 108).
+
+  b. The mouth-parts produced and pointed, fitted for piercing.
+
+    c. Palpi much shorter than the proboscis; a brownish gray fly, its
+        thorax with three rather broad whitish stripes; on each border
+        of the middle stripe and on the mesal borders of the lateral
+        stripes is a blackish brown line. Abdomen yellowish brown; on
+        the second, third and fourth segments are three brown spots
+        which may be faint or even absent. The larvæ live in dung. The
+        stable-fly (fig. 110) _Stomoxys calcitrans_
+
+    cc. Palpi nearly as long as the proboscis. Smaller species than the
+        house-fly. The horn-fly (fig. 167) _Hæmatobia irritans_
+
+  bb. Mouth-parts blunt, fitted for lapping.
+
+    c. Thorax, particularly on the sides and near the base of the wings
+        with soft golden yellow hairs among the bristles. This fly is
+        often found in the house in very early spring or even in the
+        winter. The cluster-fly, _Pollenia rudis_
+
+    cc. Thorax without golden yellow hairs among the bristles.
+
+      d. The last segment of the vein M with an abrupt angle. (fig.
+          108). The larvæ live in manure, etc. House-fly, _Musca
+          domestica_
+
+      dd. The last segment of vein M with a broad, gentle curve (fig.
+          102).
+
+        e. Eyes microscopically hairy; each abdominal segment with two
+            spots. Larvæ in dung. _Myiospila meditabunda_
+
+        ee. Eyes bare; abdomen gray and brown marbled. _Muscina_
+
+          f. With black legs and palpi. _M. assimilis_
+
+          ff. With legs more or less yellowish; palpi yellow. Larvæ in
+              decaying vegetable substances, dung, etc. _M. stabulans_
+
+It is almost universally believed that the adults of _Musca domestica_
+hibernate, remaining dormant throughout the winter in attics, around
+chimneys, and in sheltered but cold situations. This belief has been
+challenged by Skinner (1913), who maintains that all the adult flies die
+off during the fall and early winter and that the species is carried
+over in the pupal stage, and in no other way. The cluster-fly, _Pollenia
+rudis_, undoubtedly does hibernate in attics and similar situations and
+is often mistaken for the house-fly. In so far as concerns _Musca
+domestica_, the important question as to hibernation in the adult stage
+is an open one. Many observations by one of the writers (Johannsen) tend
+to confirm Dr. Skinner's conclusion, in so far as it applies to
+conditions in the latitude of New York State. Opposed, is the fact that
+various experimenters, notably Hewitt (1910) and Jepson (1909) wholly
+failed to carry pupæ through the winter.
+
+[Illustration: 108. The house or typhoid fly (Musca domestica (×4)).
+After Howard.]
+
+The house-fly breeds by preference in horse manure. Indeed, Dr. Howard,
+whose extensive studies of the species especially qualify him for
+expressing an opinion on the subject, has estimated that under ordinary
+city and town conditions, more than ninety per cent of the flies present
+in houses have come from horse stables or their vicinity. They are not
+limited to such localities, by any means, for it has been found that
+they would develop in almost any fermenting organic substance. Thus,
+they have been bred from pig, chicken, and cow manure, dirty waste
+paper, decaying vegetation, decaying meat, slaughter-house refuse,
+sawdust-sweepings, and many other sources. A fact which makes them
+especially dangerous as disease-carriers is that they breed readily in
+human excrement.
+
+The eggs are pure white, elongate ovoid, somewhat broader at the
+anterior end. They measure about one millimeter (1-25 inch) in length.
+They are deposited in small, irregular clusters, one hundred and twenty
+to one hundred and fifty from a single fly. A female may deposit as many
+as four batches in her life time. The eggs hatch in from eight to
+twenty-four hours.
+
+The newly hatched larva, or maggot (fig. 108), measures about two
+millimeters (1-12 inch) in length. It is pointed at the head end and
+blunt at the opposite end, where the spiracular openings are borne. It
+grows rapidly, molts three times and reaches maturity in from six to
+seven days, under favorable conditions.
+
+The pupal stage, like that of related flies, is passed in the old larval
+skin which, instead of being molted, becomes contracted and heavily
+chitinized, forming the so-called _puparium_ (fig. 108). The pupal stage
+may be completed in from three to six days.
+
+Thus during the warm summer months a generation of flies may be produced
+in ten to twelve days. Hewitt at Manchester, England, found the minimum
+to be eight days but states that larvæ bred in the open air in horse
+manure which had an average daily temperature of 22.5° C., occupied
+fourteen to twenty days in their development, according to the air
+temperature.
+
+After emergence, a period of time must elapse before the fly is capable
+of depositing eggs. This period has been tuned the _preoviposition_
+period. Unfortunately we have few exact data regarding this period.
+Hewitt found that the flies became sexually mature in ten to fourteen
+days after their emergence from the pupal state and four days after
+copulation they began to deposit their eggs; in other words the
+preoviposition stage was fourteen days or longer. Griffith (1908) found
+this period to be ten days. Dr. Howard believes that the time "must
+surely be shorter, and perhaps much shorter, under midsummer conditions,
+and in the freedom of the open air." He emphasizes that the point is of
+great practical importance, since it is during this period that the
+trapping and other methods of destroying the adult flies, will prove
+most useful.
+
+Howard estimates that there may be nine generations of flies a year
+under outdoor conditions in places comparable in climate to Washington.
+The number may be considerably increased in warmer climates.
+
+The rate at which flies may increase under favorable conditions is
+astounding. Various writers have given estimates of the numbers of flies
+which may develop as the progeny of a single individual, providing all
+the eggs and all the individual flies survived. Thus, Howard estimates
+that from a single female, depositing one hundred and twenty eggs on
+April 15th, there may be by September 10th, 5,598,720,000,000 adults.
+Fortunately, living forms do not produce in any such mathematical manner
+and the chief value of the figures is to illustrate the enormous
+struggle for existence which is constantly taking place in nature.
+
+Flies may travel for a considerable distance to reach food and shelter,
+though normally they pass to dwellings and other sources of food supply
+in the immediate neighborhood of their breeding places. Copeman, Howlett
+and Merriman (1911) marked flies by shaking them in a bag containing
+colored chalk. Such flies were repeatedly recovered at distances of
+eight to one thousand yards and even at a distance of seventeen hundred
+yards, nearly a mile.
+
+Hindle and Merriman (1914) continued these experiments on a large scale
+at Cambridge, England. They "do not think it likely that, as a rule,
+flies travel more than a quarter of a mile in thickly-housed areas." In
+one case a single fly was recovered at a distance of 770 yards but a
+part of this distance was across open fen-land. The surprising fact was
+brought out that flies tend to travel either _against_ or across the
+wind. The actual direction followed may be determined either directly by
+the action of the wind (positive anemotropism), or indirectly owing to
+the flies being attracted by any odor that it may convey from a source
+of food. They conclude that it is likely that the chief conditions
+favoring the disposal of flies are fine weather and a warm temperature.
+The nature of the locality is another considerable factor. Hodge (1913)
+has shown that when aided by the wind they may fly to much greater
+distances over the water. He reports that at Cleveland, Ohio, the cribs
+of the water works, situated a mile and a quarter, five miles, and six
+miles out in Lake Erie are invaded by a regular plague of flies when the
+wind blows from the city. Investigation showed that there was absolutely
+nothing of any kind in which flies could breed on the crib.
+
+The omnivorous habits of the house-fly are matters of everyday
+observation. From our view point, it is sufficient to emphasize that
+from feeding on excrement, on sputum, on open sores, or on putrifying
+matter, the flies may pass to the food or milk upon the table or to
+healthy mucous membranes, or uncontaminated wounds. There is nothing in
+its appearance to tell whether the fly that comes blithely to sup with
+you is merely unclean, or whether it has just finished feeding upon
+dejecta teeming with typhoid bacilli.
+
+[Illustration: 100. Pulvillus of foot of house-fly, showing glandular
+hairs.]
+
+The method of feeding of the house-fly has an important bearing on the
+question of its ability to transmit pathogenic organisms. Graham-Smith
+(1910) has shown that when feeding, flies frequently moisten soluble
+substances with "vomit" which is regurgitated from the crop. This is, of
+course, loaded with bacteria from previous food. When not sucked up
+again these drops of liquid dry, and produce round marks with an opaque
+center and rim and an intervening less opaque area. Fly-specks, then,
+consist of both vomit spots and feces. Graham-Smith shows a photograph
+of a cupboard window where, on an area six inches square, there were
+counted eleven hundred and two vomit marks and nine fecal deposits.
+
+From a bacteriologist's viewpoint a discussion of the possibility of a
+fly's carrying bacteria would seem superfluous. Any exposed object,
+animate or inanimate, is contaminated by bacteria and will transfer them
+if brought into contact with suitable culture media, whether such
+substance be food, or drink, open wounds, or the sterile culture media
+of the laboratory. A needle point may convey enough germs to produce
+disease. Much more readily may the house-fly with its covering of hairs
+and its sponge-like pulvilli (fig. 109) pick up and transfer bits of
+filth and other contaminated material.
+
+For popular instruction this inevitable transfer of germs by the
+house-fly is strikingly demonstrated by the oft copied illustration of
+the tracks of a fly on a sterile culture plate. Two plates of gelatine
+or, better, agar medium are prepared. Over one of these a fly (with
+wings clipped) is allowed to walk, the other is kept as a check. Both
+are put aside at room temperature, to be examined after twenty-four to
+forty-eight hours. At the end of that time, the check plate is as clear
+as ever, the one which the fly has walked is dotted with colonies of
+bacteria and fungi. The value in the experiment consists in emphasizing
+that by this method we merely render visible what is constantly
+occurring in nature.
+
+A comparable experiment which we use in our elementary laboratory work
+is to take three samples of _clean_ (preferably, sterile) fresh milk in
+sterile bottles. One of them is plugged with a pledget of cotton, into
+the second is dropped a fly from the laboratory and into the third is
+dropped a fly which has been caught feeding upon garbage or other filth.
+After a minute or two the flies are removed and the vials plugged as was
+number one. The three are then set aside at room temperature. When
+examined after twenty-four hours the milk in the first vial is either
+still sweet or has a "clean" sour odor; that of the remaining two is
+very different, for it has a putrid odor, which is usually more
+pronounced in the case of sample number three.
+
+Several workers have carried out experiments to determine the number of
+bacteria carried by flies under natural conditions. One of the most
+extended and best known of these is the series by Esten and Mason
+(1908). These workers caught flies from various sources in a sterilized
+net, placed them in a sterile bottle and poured over them a known
+quantity of sterilized water, in which they were shaken so as to wash
+the bacteria from their bodies. They found the number of bacteria on a
+single fly to range from 550 to 6,600,000. Early in the fly season the
+numbers of bacteria on flies are comparatively small, while later the
+numbers are comparatively very large. The place where flies live also
+determines largely the numbers that they carry. The lowest number, 550,
+was from a fly caught in the bacteriological laboratory, the highest
+number, 6,600,000 was the average from eighteen swill-barrel flies.
+Torrey (1912) made examination of "wild" flies from a tenement house
+district of New York City. He found "that the surface contamination of
+these 'wild' flies may vary from 570 to 4,400,000 bacteria per insect,
+and the intestinal bacterial content from 16,000 to 28,000,000."
+
+Less well known in this country is the work of Cox, Lewis, and Glynn
+(1912). They examined over four hundred and fifty naturally infected
+house-flies in Liverpool during September and early October. Instead of
+washing the flies they were allowed to swim on the surface of sterile
+water for five, fifteen, or thirty minutes, thus giving natural
+conditions, where infection occurs from vomit and dejecta of the flies,
+as well as from their bodies. They found, as might be expected, that
+flies from either insanitary or congested areas of the city contain far
+more bacteria than those from the more sanitary, less congested, or
+suburban areas. The number of aerobic bacteria from the former varied
+from 800,000 to 500,000,000 per fly and from the latter from 21,000 to
+100,000. The number of intestinal forms conveyed by flies from
+insanitary or congested areas was from 10,000 to 333,000,000 as compared
+with from 100 to 10,000 carried by flies from the more sanitary areas.
+
+Pathogenic bacteria and those allied to the food poisoning group were
+only obtained from the congested or moderately congested areas and not
+from the suburban areas, where the chances of infestation were less.
+
+The interesting fact was brought out that flies caught in milk shops
+apparently carry and obtain more bacteria than those from other shops
+with exposed food in a similar neighborhood. The writers explained this
+as probably due to the fact that milk when accessible, especially during
+the summer months, is suitable culture medium for bacteria, and the
+flies first inoculate the milk and later reinoculate themselves, and
+then more of the milk, so establishing a vicious circle.
+
+They conclude that in cities where food is plentiful flies rarely
+migrate from the locality in which they are bred, and consequently the
+number of bacteria which they carry depends upon the general standard
+of cleanliness in that locality. Flies caught in a street of modern,
+fairly high class, workmen's dwellings forming a sanitary oasis in the
+midst of a slum area, carried far less bacteria than those caught in the
+adjacent neighborhood.
+
+Thus, as the amount of dirt carried by flies in any particular locality,
+measured in the terms of bacteria, bears a definite relation to the
+habits of the people and to the state of the streets, it demonstrates
+the necessity of efficient municipal and domestic cleanliness, if the
+food of the inhabitants is to escape pollution, not only with harmless
+but also with occasional pathogenic bacteria.
+
+The above cited work is of a general nature, but, especially in recent
+years, many attempts have been made to determine more specifically the
+ability of flies to transmit pathogenic organisms. The critical reviews
+of Nuttall and Jepson (1909), Howard (1911), and Graham-Smith (1913)
+should be consulted by the student of the subject. We can only cite here
+a few of the more striking experiments.
+
+Celli (1888) fed flies on pure cultures of _Bacillus typhosus_ and
+declared that he was able to recover these organisms from the intestinal
+contents and excrement.
+
+Firth and Horrocks (1902), cited by Nuttall and Jepson, "kept _Musca
+domestica_ (also bluebottles) in a large box measuring 4 × 3 × 3 feet,
+with one side made of glass. They were fed on material contaminated with
+cultures of _B. typhosus_. Agar plates, litmus, glucose broth and a
+sheet of clean paper were at the same time exposed in the box. After a
+few days the plates and broth were removed and incubated with a positive
+result." Graham-Smith (1910) "carried out experiments with large numbers
+of flies kept in gauze cages and fed for eight hours on emulsions of _B.
+typhosus_ in syrup. After that time the infested syrup was removed and
+the flies were fed on plain syrup. _B. typhosus_ was isolated up to 48
+hours (but not later) from emulsions of their feces and from plates over
+which they walked."
+
+Several other workers, notably Hamilton (1903), Ficker (1903),
+Bertarelli (1910) Faichnie (1909), and Cochrane (1912), have isolated
+_B. typhosus_ from "wild" flies, naturally infected. The papers of
+Faichnie and of Cochrane we have not seen, but they are quoted in
+_extenso_ by Graham-Smith (1913).
+
+On the whole, the evidence is conclusive that typhoid germs not only may
+be accidentally carried on the bodies of house-flies but may pass
+through their bodies and be scattered in a viable condition in the feces
+of the fly for at least two days after feeding. Similar, results have
+been reached in experiments with cholera, tuberculosis and yaws, the
+last-mentioned being a spirochæte disease. Darling (1913) has shown that
+murrina, a trypanosome disease of horses and mules in the Canal zone is
+transmitted by house-flies which feed upon excoriated patches of
+diseased animals and then pass to cuts and galls of healthy animals.
+
+Since it is clear that flies are abundantly able to disseminate viable
+pathogenic bacteria, it is important to consider whether they have
+access to such organisms in nature. A consideration of the method of
+spread of typhoid will serve to illustrate the way in which flies may
+play an important rôle.
+
+Typhoid fever is a specific disease caused by _Bacillus typhosus_, and
+by it alone. The causative organism is to be found in the excrement and
+urine of patients suffering from the disease. More than that, it is
+often present in the dejecta for days, weeks, or even months and years,
+after the individual has recovered from the disease. Individuals so
+infested are known as "typhoid carriers" and they, together with those
+suffering from mild cases, or "walking typhoid," are a constant menace
+to the health of the community in which they are found.
+
+Human excrement is greedily visited by flies, both for feeding and for
+ovipositing. The discharges of typhoid patients, or of chronic
+"carriers," when passed in the open, in box privies, or camp latrines,
+or the like, serve to contaminate myriads of the insects which may then
+spread the germ to human food and drink. Other intestinal diseases may
+be similarly spread. There is abundant epidæmiological evidence that
+infantile diarrhœa, dysentery, and cholera may be so spread.
+
+Stiles and Keister (1913) have shown that spores of _Lamblia
+intestinalis_, a flagellate protozoan living in the human intestine, may
+be carried by house-flies. Though this species is not normally
+pathogenic, one or more species of _Entamœba_ are the cause of a type
+of a highly fatal tropical dysentery. Concerning it, and another
+protozoan parasite of man, they say, "If flies can carry _Lamblia_
+spores measuring 10 to 7µ, and bacteria that are much smaller, and
+particles of lime that are much larger, there is no ground to assume
+that flies may not carry _Entamœba_ and _Trichomonas_ spores."
+
+Tuberculosis is one of the diseases which it is quite conceivable may be
+carried occasionally. The sputum of tubercular patients is very
+attractive to flies, and various workers, notably Graham-Smith, have
+found that _Musca domestica_ may distribute the bacillus for several
+days after feeding on infected material.
+
+A type of purulent opthalmia which is very prevalent in Egypt is often
+said to be carried by flies. Nuttall and Jepson (1909) consider that the
+evidence regarding the spread of this disease by flies is conclusive and
+that the possibility of gonorrhœal secretions being likewise conveyed
+cannot be denied.
+
+Many studies have been published, showing a marked agreement between the
+occurrence of typhoid and other intestinal diseases and the prevalence
+of house-flies. The most clear-cut of these are the studies of the Army
+Commission appointed to investigate the cause of epidemics of enteric
+fever in the volunteer camps in the Southern United States during the
+Spanish-American War. Though their findings as presented by Vaughan
+(1909), have been quoted very many times, they are so germane to our
+discussion that they will bear repetition:
+
+"Flies swarmed over infected fecal matter in the pits and fed upon the
+food prepared for the soldiers in the mess tents. In some instances
+where lime had recently been sprinkled over the contents of the pits,
+flies with their feet whitened with lime were seen walking over the
+food." Under such conditions it is no wonder that "These pests had
+inflicted greater loss upon American soldiers than the arms of Spain."
+
+Similar conditions prevailed in South Africa during the Boer War. Seamon
+believes that very much of the success of the Japanese in their fight
+against Russia was due to the rigid precautions taken to prevent the
+spread of disease by these insects and other means.
+
+Veeder has pointed out that the characteristics of a typical fly-borne
+epidemic of typhoid are that it occurs in little neighborhood epidemics,
+extending by short leaps from house to house, without regard to water
+supply or anything else in common. It tends to follow the direction of
+prevailing winds (cf. the conclusions of Hindle and Merriman). It occurs
+during warm weather. Of course, when the epidemic is once well under
+way, other factors enter into its spread.
+
+In general, flies may be said to be the chief agency in the spread of
+typhoid in villages and camps. In cities with modern sewer systems they
+are less important, though even under the best of such conditions, they
+are important factors. Howard has emphasized that in such cities there
+are still many uncared-for box privies and that, in addition, the
+deposition of feces overnight in uncared-for waste lots and alleys is
+common.
+
+Not only unicellular organisms, such as bacteria and protozoa, but also
+the eggs, embryos and larvæ of parasitic worms have been found to be
+transported by house-flies. Ransom (1911) has found that _Habronema
+muscæ_, a nematode worm often found in adult flies, is the immature
+stage of a parasite occurring in the stomach of the horse. The eggs or
+embryos passing out with the feces of the horse, are taken up by fly
+larvæ and carried over to the imago stage.
+
+Grassi (1883), Stiles (1889), Calandruccio (1906), and especially Nicoll
+(1911), have been the chief investigators of the ability of house-flies
+to carry the ova and embryos of human intestinal parasites. Graham-Smith
+(1913) summarizes the work along this line as follows:
+
+"It is evident from the investigations that have been quoted that
+house-flies and other species are greatly attracted to the ova of
+parasitic worms contained in feces and other materials, and make great
+efforts to ingest them. Unless the ova are too large they often succeed,
+and the eggs are deposited uninjured in their feces, in some cases up to
+the third day at least. The eggs may also be carried on their legs or
+bodies. Under suitable conditions, food and fluids may be contaminated
+with the eggs of various parasitic worms by flies, and in one case
+infection of the human subject has been observed. Feces containing
+tape-worm segments may continue to be a source of infection for as long
+as a fortnight. Up to the present, however, there is no evidence to show
+what part flies play in the dissemination of parasitic worms under
+natural conditions."
+
+Enough has been said to show that the house-fly must be dealt with as a
+direct menace to public health. Control measures are not merely matters
+of convenience but are of vital importance.
+
+Under present conditions the speedy elimination of the house-fly is
+impossible and the first thing to be considered is methods of protecting
+food and drink from contamination. The first of these methods is the
+thorough screening of doors and windows to prevent the entrance of
+flies. In the case of kitchen doors, the flies, attracted by odors, are
+likely to swarm onto the screen and improve the first opportunity for
+gaining an entrance. This difficulty can be largely avoided by
+screening-in the back porch and placing the screen door at one end
+rather than directly before the door.
+
+The use of sticky fly paper to catch the pests that gain entrance to the
+house is preferable to the various poisons often used. Of the latter,
+formalin (40 per cent formaldehyde) in the proportion of two
+tablespoonfuls to a pint of water is very efficient, if all other
+liquids are removed or covered, so that the flies must depend on the
+formalin for drink. The mixture is said to be made more attractive by
+the addition of sugar or milk, though we have found the plain solution
+wholly satisfactory, under proper conditions. It should be emphasized
+that this formalin mixture is not perfectly harmless, as so often
+stated. There are on record cases of severe and even fatal poisoning
+from the accidental drinking of solutions.
+
+When flies are very abundant in a room they can be most readily gotten
+rid of by fumigation with sulphur, or by the use of pure pyrethrum
+powder either burned or puffed into the air. Herrick (1913) recommends
+the following method: "At night all the doors and windows of the kitchen
+should be closed; fresh powder should be sprinkled over the stove, on
+the window ledges, tables, and in the air. In the morning flies will be
+found lying around dead or stupified. They may then be swept up and
+burned." This method has proved very efficaceous in some of the large
+dining halls in Ithaca.
+
+The writers have had little success in fumigating with the vapors of
+carbolic acid, or carbolic acid and gum camphor, although these methods
+will aid in driving flies from a darkened room.
+
+All of these methods are but makeshifts. As Howard has so well put it,
+"the truest and simplest way of attacking the fly problem is to prevent
+them from breeding, by the treatment or abolition of all places in which
+they can breed. To permit them to breed undisturbed and in countless
+numbers, and to devote all our energy to the problem of keeping them out
+of our dwellings, or to destroy them after they have once entered in
+spite of all obstacles, seems the wrong way to go about it."
+
+We have already seen that _Musca domestica_ breeds in almost any
+fermenting organic material. While it prefers horse manure, it breeds
+also in human feces, cow dung and that of other animals, and in refuse
+of many kinds. To efficiently combat the insect, these breeding places
+must be removed or must be treated in some such way as to render them
+unsuitable for the development of the larvæ. Under some conditions
+individual work may prove effective, but to be truly efficient there
+must be extensive and thorough coöperative efforts.
+
+Manure, garbage, and the like should be stored in tight receptacles and
+carted away at least once a week. The manure may be carted to the fields
+and spread. Even in spread manure the larvæ may continue their
+development. Howard points out that "it often happens that after a lawn
+has been heavily manured in early summer the occupants of the house will
+be pestered with flies for a time, but finding no available breeding
+place these disappear sooner or later. Another generation will not breed
+in the spread manure."
+
+Hutchinson (1914) has emphasized that the larvæ of houseflies have
+deeply engrained the habit of migrating in the prepupal stage and has
+shown that this offers an important point of attack in attempts to
+control the pest. He has suggested that maggot traps might be developed
+into an efficient weapon in the warfare against the house-fly. Certain
+it is that the habit greatly simplifies the problem of treating the
+manure for the purpose of killing the larvæ.
+
+There have been many attempts to find some cheap chemical which would
+destroy fly larvæ in horse manure without injuring the bacteria or
+reducing the fertilizing values of the manure. The literature abounds in
+recommendations of kerosene, lime, chloride of lime, iron sulphate, and
+other substances, but none of them has met the situation. The whole
+question has been gone into thoroughly by Cook, Hutchinson and Scales
+(1914), who tested practically all of the substances which have been
+recommended. They find that by far the most effective, economical, and
+practical of the substances is borax in the commercial form in which it
+is available throughout the country.
+
+"Borax increases the water-soluble nitrogen, ammonia and alkalinity of
+manure and apparently does not permanently injure the bacterial flora.
+The application of manure treated with borax at the rate of 0.62 pound
+per eight bushels (10 cubic feet) to soil does not injure the plants
+thus far tested, although its cumulative effect, if any, has not been
+determined."
+
+As their results clearly show that the substances so often recommended
+are inferior to borax, we shall quote in detail their directions for
+treating manure so as to kill fly eggs and maggots.
+
+"Apply 0.62 pound borax or 0.75 pound calcined colemanite to every 10
+cubic feet (8 bushels) of manure immediately on its removal from the
+barn. Apply the borax particularly around the outer edges of the pile
+with a flour sifter or any fine sieve, and sprinkle two or three gallons
+of water over the borax-treated manure.
+
+"The reason for applying the borax to the fresh manure immediately after
+its removal from the stable is that the flies lay their eggs on the
+fresh manure, and borax, when it comes in contact with the eggs,
+prevents their hatching. As the maggots congregate at the outer edge of
+the pile, most of the borax should be applied there. The treatment
+should be repeated with each addition of fresh manure, but when the
+manure is kept in closed boxes, less frequent applications will be
+sufficient. When the calcined colemanite is available, it may be used at
+the rate of 0.75 pound per 10 cubic feet of manure, and is a cheaper
+means of killing the maggots. In addition to the application of borax to
+horse manure to kill fly larvæ, it may be applied in the same proportion
+to other manures, as well as to refuse and garbage. Borax may also be
+applied to the floors and crevices in barns, stables, markets, etc., as
+well as to street sweepings, and water should be added as in the
+treatment of horse manure. After estimating the amount of material to be
+treated and weighing the necessary amount of borax, a measure may be
+used which will hold the proper amount, thus avoiding the subsequent
+weighings.
+
+"While it can be safely stated that no injurious action will follow the
+application of manure treated with borax at the rate of 0.62 pound for
+eight bushels, or even larger amounts in the case of some plants,
+nevertheless the borax-treated manure has not been studied in connection
+with the growth of all crops, nor has its cumulative effect been
+determined. It is therefore recommended that not more than 15 tons per
+acre of the borax-treated manure should be applied to the field. As
+truckmen use considerably more than this amount, it is suggested that
+all cars containing borax-treated manure be so marked, and that
+public-health officials stipulate in their directions for this treatment
+that not over 0.62 pound for eight bushels of manure be used, as it has
+been shown that larger amounts of borax will injure most plants. It is
+also recommended that all public-health officials and others, in
+recommending the borax treatment for killing fly eggs and maggots in
+manure, warn the public against the injurious effects of large amounts
+of borax on the growth of plants."
+
+"The amount of manure from a horse varies with the straw or other
+bedding used, but 12 or 15 bushels per week represent the approximate
+amount obtained. As borax costs from five to six cents per pound in
+100-pound lots in Washington, it will make the cost of the borax
+practically one cent per horse, per day. And if calcined colemanite is
+purchased in large shipments the cost should be considerably less."
+
+Hodge (1910) has approached the problem of fly extermination from
+another viewpoint. He believes that it is practical to trap flies out of
+doors during the preoviposition period, when they are sexually immature,
+and to destroy such numbers of them that the comparatively few which
+survive will not be able to lay eggs in sufficient numbers to make the
+next generation a nuisance. To the end of capturing them in enormous
+numbers he has devised traps to be fitted over garbage cans, into stable
+windows, and connected with the kitchen window screens. Under some
+conditions this method of attack has proved very satisfactory.
+
+One of the most important measures for preventing the spread of disease
+by flies is the abolition of the common box privy. In villages and rural
+districts this is today almost the only type to be found. It is the
+chief factor in the spread of typhoid and other intestinal diseases, as
+well as intestinal parasites. Open and exposed to myriads of flies which
+not only breed there but which feed upon the excrement, they furnish
+ideal conditions for spreading contamination. Even where efforts are
+made to cover the contents with dust, or ashes, or lime, flies may
+continue to breed unchecked. Stiles and Gardner have shown that
+house-flies buried in a screened stand-pipe forty-eight inches under
+sterile sand came to the surface. Other flies of undetermined species
+struggled up through seventy-two inches of sand.
+
+So great is the menace of the ordinary box privy that a number of
+inexpensive and simple sanitary privies have been designed for use where
+there are not modern sewer systems. Stiles and Lumsden (1911) have given
+minute directions for the construction of one of the best types, and
+their bulletin should be obtained by those interested.
+
+Another precaution which is of fundamental importance in preventing the
+spread of typhoid, is that of disinfecting all discharges from patients
+suffering with the disease. For this purpose, quick-lime is the cheapest
+and is wholly satisfactory. In chamber vessels it should be used in a
+quantity equal to that of the discharge to be treated. It should be
+allowed to act for two hours. Air-slaked lime is of no value whatever.
+Chloride of lime, carbolic acid, or formalin may be used, but are more
+expensive. Other intestinal diseases demand similar precautions.
+
+
+STOMOXYS CALCITRANS, THE STABLE-FLY--It is a popular belief that
+house-flies bite more viciously just before a rain. As a matter of
+fact, the true house-flies never bite, for their mouth-parts are not
+fitted for piercing. The basis of the misconception is the fact that a
+true biting fly, _Stomoxys calcitrans_ (fig. 110), closely resembling
+the house-fly, is frequently found in houses and may be driven in in
+greater numbers by muggy weather. From its usual habitat this fly is
+known as the "stable-fly" or, sometimes as the "biting house-fly."
+
+_Stomoxys calcitrans_ may be separated from the house-fly by the use of
+the key on p. 145. It may be more fully characterized as follows:
+
+The eyes of the male are separated by a distance equal to one-fourth of
+the diameter of the head, in the female by one-third. The frontal stripe
+is black, the cheeks and margins of the orbits silvery-white. The
+antennæ are black, the arista feathered on the upper side only. The
+proboscis is black, slender, fitted for piercing and projects forward in
+front of the head. The thorax is grayish, marked by four conspicuous,
+more or less complete black longitudinal stripes; the scutellum is
+paler; the macrochætæ are black. The abdomen is gray, dorsally with
+three brown spots on the second and third segments and a median spot on
+the fourth. These spots are more pronounced in the female. The legs are
+black, the pulvilli distinct. The wings are hyaline, the vein M_{1+2}
+less sharply curved than in the house-fly, the apical cell being thus
+more widely open (cf. fig. 110). Length 7 mm.
+
+[Illustration: 110. Stomoxys calcitrans; adult, larva, puparium and
+details, (×5). After Howard.]
+
+This fly is widely distributed, being found the world over. It was
+probably introduced into the United States, but has spread to all parts
+of the country. Bishopp (1913) regards it as of much more importance as
+a pest of domestic animals in the grain belt than elsewhere in the
+United States. The life-history and habits of this species have assumed
+a new significance since it has been suggested that it may transmit the
+human diseases, infantile paralysis and pellagra. In this country, the
+most detailed study of the fly is that of Bishopp (1913) whose data
+regarding the life cycle are as follows:
+
+The eggs like those of the house-fly, are about one mm. in length. Under
+a magnifying glass they show a distinct furrow along one side. When
+placed on any moist substance they hatch in from one to three days after
+being deposited.
+
+The larva or maggots (fig. 110) have the typical shape and actions of
+most maggots of the Muscid group. They can be distinguished from those
+of the house-fly as the stigma-plates are smaller, much further apart,
+with the slits less sinuous. Development takes place fairly rapidly when
+the proper food conditions are available and the growth is completed
+within eleven to thirty or more days.
+
+The pupa (fig. 110), like that of related flies, undergoes its
+development within the contracted and hardened last larval skin, or
+puparium. This is elongate oval, slightly thicker towards the head end,
+and one-sixth to one-fourth of an inch in length. The pupal stage
+requires six to twenty days, or in cool weather considerably longer.
+
+The life-cycle of the stable-fly is therefore considerably longer than
+that of _Musca domestica_. Bishopp found that complete development might
+be undergone in nineteen days, but that the average period was somewhat
+longer, ranging from twenty-one to twenty-five days, where conditions
+are very favorable. The longest period which he observed was forty-three
+days, though his finding of full grown larvæ and pupæ in straw during
+the latter part of March, in Northern Texas, showed that development may
+require about three months, as he considered that these stages almost
+certainly developed from eggs deposited the previous December.
+
+The favorite breeding place, where available, seems to be straw or
+manure mixed with straw. It also breeds in great numbers in
+horse-manure, in company with _Musca domestica_.
+
+Newstead considers that in England the stable-fly hibernates in the
+pupal stage. Bishopp finds that in the southern part of the United
+States there is no true hibernation, as the adults have been found to
+emerge at various times during the winter. He believes that in the
+northern United States the winter is normally passed in the larval and
+pupal stages, and that the adults which have been observed in heated
+stables in the dead of winter were bred out in refuse within the warm
+barns and were not hibernating adults.
+
+Graham-Smith (1913) states that although the stable-fly frequents stable
+manure, it is probably not an important agent in distributing the
+organisms of intestinal diseases. Bishopp makes the important
+observation that "it has never been found breeding in human excrement
+and does not frequent malodorous places, which are so attractive to the
+house-fly. Hence it is much less likely to carry typhoid and other germs
+which may be found in such places."
+
+Questions of the possible agency of _Stomoxys calcitrans_ in the
+transmission of infantile paralysis and of pellagra, we shall consider
+later.
+
+
+OTHER ARTHROPODS WHICH MAY SERVE AS SIMPLE CARRIERS OF PATHOGENIC
+ORGANISMS--It should be again emphasized that any insect which has
+access to, and comes in contact with, pathogenic organisms and then
+passes to the food, or drink, or the body of man, may serve as a simple
+carrier of disease. In addition to the more obvious illustrations, an
+interesting one is the previously cited case of the transfer of
+_Dermatobia cyaniventris_ by a mosquito (fig. 81-84). Darling (1913) has
+shown that in the tropics, the omnipresent ants may be important factors
+in the spread of disease.
+
+
+
+
+CHAPTER VI
+
+ARTHROPODS AS DIRECT INOCULATORS OF DISEASE GERMS
+
+
+We have seen that any insect which, like the house-fly, has access to
+disease germs and then comes into contact with the food or drink of man,
+may serve to disseminate disease. Moreover, it has been clearly
+established that a contaminated insect, alighting upon wounded or
+abraded surfaces, may infect them. These are instances of mere
+accidental, mechanical transfer of pathogenic organisms.
+
+Closely related are the instances of direct inoculation of disease germs
+by insects and other arthropods. In this type, a blood-sucking species
+not only takes up the germs but, passing to a healthy individual, it
+inserts its contaminated mouth-parts and thus directly inoculates its
+victim. In other words, the disease is transferred just as blood
+poisoning may be induced by the prick of a contaminated needle, or as
+the laboratory worker may inoculate an experimental animal.
+
+Formerly, it was supposed that this method of the transfer of disease by
+arthropods was a very common one and many instances are cited in the
+earlier literature of the subject. It is, however, difficult to draw a
+sharp line between such cases and those in which, on the one hand, the
+arthropod serves as a mere passive carrier or, on the other hand, serves
+as an essential host of the pathogenic organism. More critical study of
+the subject has led to the belief that the importance of the rôle of
+arthropods as direct inoculators has been much overestimated.
+
+The principal reason for regarding this phase of the subject as
+relatively unimportant, is derived from a study of the habits of the
+blood-sucking species. It is found that, in general, they are
+intermittent feeders, visiting their hosts at intervals and then
+abstaining from feeding for a more or less extended period, while
+digesting their meal. In the meantime, most species of bacteria or of
+protozoan parasites with which they might have contaminated their
+mouth-parts, would have perished, through inability to withstand drying.
+
+In spite of this, it must be recognized that this method of transfer
+does occur and must be reckoned with in any consideration of the
+relations of insects to disease. We shall first cite some general
+illustrations and shall then discuss the rôle of fleas in the spreading
+of bubonic plague, an illustration which cannot be regarded as typical,
+since it involves more than mere passive carriage.
+
+
+SOME ILLUSTRATIONS OF DIRECT INOCULATION OF DISEASE GERMS BY ARTHROPODS
+
+In discussing poisonous arthropods, we have already emphasized that
+species which are of themselves innocuous to man, may occasionally
+introduce bacteria by their bite or sting and thus cause more or less
+severe secondary symptoms. That such cases should occur, is no more than
+is to be expected. The mouth-parts or the sting of the insect are not
+sterile and the chances of their carrying pyogenic organisms are always
+present.
+
+More strictly falling in the category of transmission of disease germs
+by direct inoculation are the instances where the insect, or related
+form, feeds upon a diseased animal and passes promptly to a healthy
+individual which it infects. Of such a nature are the following:
+
+Various species of biting flies are factors in the dissemination of
+anthrax, an infectious and usually fatal disease of animals and,
+occasionally, of man. That the bacteria with which the blood of diseased
+animals teem shortly before death might be transmitted by such insects
+has long been contended, but the evidence in support of the view has
+been unsatisfactory. Recently, Mitzmain (1914) has reported a series of
+experiments which show conclusively that the disease may be so conveyed
+by a horse-fly, _Tabanus striatus_, and by the stable-fly, _Stomoxys
+calcitrans_.
+
+Mitzmain's experiments were tried with an artificially infected guinea
+pig, which died of the disease upon the third day. The flies were
+applied two and one-half hours, to a few minutes, before the death of
+the animal. With both species the infection was successfully transferred
+to healthy guinea pigs by the direct method, in which the flies were
+interrupted while feeding on the sick animal. The evidence at hand does
+not warrant the conclusion that insect transmission is the rule in the
+case of this disease.
+
+The nagana, or tsetse-fly disease of cattle is the most virulent disease
+of domestic animals in certain parts of Africa. It is caused by a
+protozoan blood parasite, _Trypanosoma brucei_, which is conveyed to
+healthy animals by the bite of _Glossina morsitans_ and possibly other
+species of tsetse-flies. The flies remain infective for forty-eight
+hours after feeding on a diseased animal. The insect also serves as an
+essential host of the parasite.
+
+Surra, a similar trypanosomiasis affecting especially horses and mules,
+occurs in southern Asia, Malaysia, and the Philippines where the
+tsetse-flies are not to be found. It is thought to be spread by various
+species of blood-sucking flies belonging to the genera _Stomoxys_,
+_Hæmatobia_, and _Tabanus_. Mitzmain (1913) demonstrated that in the
+Philippines it is conveyed mechanically by _Tabanus striatus_.
+
+The sleeping sickness of man, in Africa, has also been supposed to be
+directly inoculated by one, or several, species of tsetse-flies. It is
+now known that the fly may convey the disease for a short time after
+feeding, but that there is then a latent period of from fourteen to
+twenty-one days, after which it again becomes infectious. This indicates
+that in the meantime the parasite has been undergoing some phase of its
+life-cycle and that the fly serves as an intermediate host. We shall
+therefore consider it more fully under that grouping.
+
+These are a few of the cases of direct inoculation which may be cited as
+of the simpler type. We shall next consider the rôle of the flea in the
+dissemination of the bubonic plague, an illustration complicated by the
+fact that the bacillus multiples within the insect and may be indirectly
+inoculated.
+
+
+THE RÔLE OF FLEAS IN THE TRANSMISSION OF THE PLAGUE
+
+The plague is a specific infectious disease caused by _Bacillus pestis_.
+It occurs in several forms, of which the bubonic and the pneumonic are
+the most common. According to Wyman, 80 per cent of the human cases are
+of the bubonic type. It is a disease which, under the name of oriental
+plague, the pest, or the black death, has ravaged almost from time
+immemorial the countries of Africa, Asia, and Europe. The record of its
+ravages are almost beyond belief. In 542 A. D. it caused in one day ten
+thousand deaths in Constantinople. In the 14th century it was introduced
+from the East and prevailed throughout Armenia, Asia Minor, Egypt and
+Northern Africa and Europe. Hecker estimates that one-fourth of the
+population of Europe, or twenty-five million persons, died in the
+epidemic of that century. From then until the 17th century it was almost
+constantly present in Europe, the great plague of London, in 1665
+killing 68,596 out of a population of 460,000. Such an epidemic would
+mean for New York City a proportionate loss of over 600,000 in a single
+year. It is little wonder that in the face of such an appalling disaster
+suspicion and credulity were rife and the wildest demoralization ensued.
+
+During the 14th century the Jews were regarded as responsible for the
+disease, through poisoning wells, and were subjected to the most
+incredible persecution and torture. In Milan the visitation of 1630 was
+credited to the so-called anointers,--men who were supposed to spread
+the plague by anointing the walls with magic ointment--and the most
+horrible tortures that human ingenuity could devise were imposed on
+scores of victims, regardless of rank or of public service (fig. 112,
+a). Manzoni's great historical novel, "The Betrothed" has well pictured
+conditions in Italy during this period.
+
+[Illustration: 111. A contemporaneous engraving of the pest hospital in
+Vienna in 1679. After Peters.]
+
+In modern times the plague is confined primarily to warm climates, a
+condition which has been brought about largely through general
+improvement in sanitary conditions.
+
+At present, the hotbed of the disease is India, where there were
+1,040,429 deaths in 1904 and where in a period of fifteen years, ending
+with January 1912, there were over 15,000,000 deaths. The reported
+deaths in that country for 1913 totaled 198,875.
+
+During the winter of 1910-11 there occurred in Manchuria and North China
+a virulent epidemic of the pneumonic plague which caused the death of
+nearly 50,000 people. The question as to its origin and means of spread
+will be especially referred to later.
+
+[Illustration: 112 a. A medieval method of combating the plague. The
+persecution of the anointers in Milan in 1630. From a copy of "Il
+processi originale degli untori" in the library of Cornell University.]
+
+Until recent years, the plague had not been known to occur in the New
+World but there were outbreaks in Brazil and Hawaii in 1899, and in 1900
+there occurred the first cases in San Francisco. In California there
+were 125 cases in the period 1900-04; three cases in the next three
+years and then from May 1907 to March 1908, during the height of the
+outbreak, 170 cases. Since that time there have been only sporadic
+cases, the last case reported being in May 1914. Still more recent were
+the outbreaks in the Philippine Islands, Porto Rico, and Cuba.
+
+On June 24, 1914, there was recognized a case of human plague in New
+Orleans. The Federal Health Service immediately took charge, and
+measures for the eradication of the disease were vigorously enforced. Up
+to October 10, 1914 there had been reported 30 cases of the disease in
+man, and 181 cases of plague in rats.
+
+[Illustration: 112 b. The modern method of combating the plague. A day's
+catch of rats in the fight against plague in San Francisco. Courtesy of
+Review of Reviews.]
+
+The present-day methods of combating bubonic plague are well illustrated
+by the fight in San Francisco. Had it not been for the strenuous and
+radical anti-plague campaign directed by the United States Marine
+Hospital Service we might have had in our own country an illustration of
+what the disease can accomplish. On what newly acquired knowledge was
+this fight based?
+
+The basis was laid in 1894, when the plague bacillus was first
+discovered. All through the centuries, before and during the Christian
+era, down to 1894, the subject was enveloped in darkness and there had
+been a helpless, almost hopeless struggle in ignorance on the part of
+physicians, sanitarians, and public health officials against the ravages
+of this dread disease. Now its cause, method of propagation and means to
+prevent its spread are matters of scientific certainty.
+
+After the discovery of the causative organism, one of the first advances
+was the establishment of the identity of human plague and that of
+rodents. It had often been noted that epidemics of the human disease
+were preceded by great epizootics among rats and mice. So well
+established was this fact that with the Chinese, unusual mortality among
+these rodents was regarded as foretelling a visitation of the human
+disease. That there was more than an accidental connection between the
+two was obvious when Yersin, the discoverer of _Bacillus pestis_,
+announced that during an epidemic the rats found dead in the houses and
+in the streets almost always contain the bacillus in great abundance in
+their organs, and that many of them exhibit veritable buboes.
+
+Once it was established that the diseases were identical, the attention
+of the investigators was directed to a study of the relations between
+that of rats and of humans, and evidence accumulated to show that the
+bubonic plague was primarily a disease of rodents and that in some
+manner it was conveyed from them to man.
+
+There yet remained unexplained the method of transfer from rat to man.
+As long ago as the 16th century, Mercuralis suggested that house-flies
+were guilty of disseminating the plague but modern investigation, while
+blaming the fly for much in the way of spreading disease, show that it
+is an insignificant factor in this case.
+
+Search for blood-sucking insects which would feed on both rodents and
+man, and which might therefore be implicated, indicated that the fleas
+most nearly met the conditions. At first it was urged that rat fleas
+would not feed upon man and that the fleas ordinarily attacking man
+would not feed upon rats. More critical study of the habits of fleas
+soon showed that these objections were not well-founded. Especially
+important was the evidence that soon after the death of their host, rat
+fleas deserted its body and might then become a pest in houses where
+they had not been noticed before.
+
+Attention was directed to the fact that while feeding, fleas are in the
+habit of squirting blood from the anus and that in the case of those
+which had fed upon rats and mice dying of the plague, virulent plague
+bacilli were to be found in such blood. Liston (1905) even found, and
+subsequent investigations confirmed, that the plague bacilli multiply in
+the stomach of the insect and that thus the blood ejected was richer in
+the organisms than was that of the diseased animal. It was found that a
+film of this infected blood spread out under the body of the flea and
+that thus the bacilli might be inoculated by the bite of the insect and
+by scratching.
+
+Very recently, Bacot and Martin (1914) have paid especial attention to
+the question of the mechanism of the transmission of the plague bacilli
+by fleas. They believe that plague infested fleas regurgitate blood
+through the mouth, and that under conditions precluding the possibility
+of infection by dejecta, the disease may be thus transmitted. The
+evidence does not seem sufficient to establish that this is the chief
+method of transmission.
+
+Conclusive experimental proof that fleas transmit the disease is further
+available from a number of sources. The most extensive series of
+experiments is that of the English Plague Commission in India, which
+reported in 1906 that:
+
+On thirty occasions a healthy rat contracted plague in sequence of
+living in the neighborhood of a plague infected rat under circumstances
+which prevented the healthy rat coming in contact with either the body
+or excreta of the diseased animal.
+
+In twenty-one experiments out of thirty-eight, healthy rats living in
+flea-proof cages contracted plague when exposed to rat fleas
+(_Xenopsylla cheopis_), collected from rats dead or dying of septicæmic
+plague.
+
+Close contact of plague-infected with healthy animals, if fleas are
+excluded, does not give rise to an epizootic among the latter. As the
+huts were never cleaned out, close contact included contact with feces
+and urine of infected animals, and contact with, and eating of food
+contaminated with feces and urine of infected animals, as well as pus
+from open plague ulcers. Close contact of young, even when suckled by
+plague-infected mothers, did not give the disease to the former.
+
+If fleas are present, then the epizootic, once started, spreads from
+animal to animal, the rate of progress being in direct proportion to the
+number of fleas.
+
+Aerial infection was excluded. Thus guinea-pigs suspended in a cage two
+feet above the ground did not contract the disease, while in the same
+hut those animals allowed to run about and those placed two inches above
+the floor became infected. It had previously been found that a rat flea
+could not hop farther than about five inches.
+
+Guinea pigs and monkeys were placed in plague houses in pairs, both
+protected from soil contact infection and both equally exposed to aerial
+infection, but one surrounded with a layer of tangle-foot paper and the
+other surrounded with a layer of sand. The following observations were
+made:
+
+(_a_) Many fleas were caught in the tangle-foot, a certain proportion of
+which were found on dissection to contain in their stomachs abundant
+bacilli microscopically identical with plague bacilli. Out of
+eighty-five human fleas dissected only one contained these bacilli,
+while out of seventy-seven rat fleas twenty-three were found thus
+infected.
+
+(_b_) The animals surrounded with tangle-foot in no instance developed
+plague, while several (24 per cent) of the non-protected animals died of
+the disease.
+
+Thus, the experimental evidence that fleas transmit the plague from rat
+to rat, from rats to guinea pigs, and from rats to monkeys is
+indisputable. There is lacking direct experimental proof of its transfer
+from rodents to man but the whole chain of indirect evidence is so
+complete that there can be no doubt that such a transfer does occur so
+commonly that in the case of bubonic plague it must be regarded as the
+normal method.
+
+Rats are not the only animals naturally attacked by the plague but as
+already suggested, it occurs in various other rodents. In California the
+disease has spread from rats to ground squirrels (_Otospermophilus
+beecheyi_), a condition readily arising from the frequency of
+association of rats with the squirrels in the neighborhood of towns, and
+from the fact that the two species of fleas found on them are also found
+on rats. While the danger of the disease being conveyed from squirrels
+to man is comparatively slight, the menace in the situation is that the
+squirrels may become a more or less permanent reservoir of the disease
+and infect rats, which may come into more frequent contact with man.
+
+The tarbagan (_Arctomys bobac_), is a rodent found in North Manchuria,
+which is much prized for its fur. It is claimed that this animal is
+extremely susceptible to the plague and there is evidence to indicate
+that it was the primary source of the great outbreak of pneumonic plague
+which occurred in Manchuria and North China during the winter of
+1910-11.
+
+Of fleas, any species which attacks both rodents and man may be an agent
+in the transmission of the plague. We have seen that in India the
+species most commonly implicated is the rat flea, _Xenopsylla cheopis_,
+(= _LÅ“mopsylla_ or _Pulex cheopis_) (fig. 89). This species has also
+been found commonly on rats in San Francisco. The cat flea,
+_Ctenocephalus felis_, the dog flea, _Ctenocephalus canis_, the human
+flea, _Pulex irritans_, the rat fleas, _Ceratophyllus fasciatus_ and
+_Ctenopsyllus musculi_ have all been shown to meet the conditions.
+
+But, however clear the evidence that fleas are the most important agent
+in the transfer of plague, it is a mistake fraught with danger to assume
+that they are the only factor in the spread of the disease. The
+causative organism is a bacillus and is not dependent upon any insect
+for the completion of its development.
+
+Therefore, any blood-sucking insect which feeds upon a plague infected
+man or animal and then passes to a healthy individual, conceivably might
+transfer the bacilli. Verjbitski (1908) has shown experimentally that
+bed-bugs may thus convey the disease. Hertzog found the bacilli in a
+head-louse, _Pediculus humanus_, taken from a child which had died from
+the plague, and McCoy found them in a louse taken from a plague-infected
+squirrel. On account of their stationary habits, the latter insects
+could be of little significance in spreading the disease.
+
+Contaminated food may also be a source of danger. While this source,
+formerly supposed to be the principal one, is now regarded as
+unimportant, there is abundant experimental evidence to show that it
+cannot be disregarded. It is believed that infection in this way can
+occur only when there is some lesion in the alimentary canal.
+
+Still more important is the proof that in pneumonic plague the patient
+is directly infective and that the disease is spread from man to man
+without any intermediary. Especially conclusive is the evidence obtained
+by Drs. Strong and Teague during the Manchurian epidemic of 1910-11.
+They found that during coughing, in pneumonic plague cases, even when
+sputum visible to the naked eye is not expelled, plague bacilli in large
+numbers may become widely disseminated into the surrounding air. By
+exposing sterile plates before patients who coughed a single time, very
+numerous colonies of the bacillus were obtained.
+
+But the great advance which has been made rests on the discovery that
+bubonic plague is in the vast majority of cases transmitted by the flea.
+The pneumonic type forms a very small percentage of the human cases and
+even with it, the evidence indicates that the original infection is
+derived from a rodent through the intermediary of the insect.
+
+So modern prophylactic measures are directed primarily against the rat
+and fleas. Ships coming from infected ports are no longer disinfected
+for the purpose of killing the plague germs, but are fumigated to
+destroy the rats and the fleas which they might harbor. When anchored at
+infected ports, ships must observe strenuous precautions to prevent the
+ingress of rats. Cargo must be inspected just before being brought on
+board, in order to insure its freedom from rats. Even lines and hawsers
+must be protected by large metal discs or funnels, for rats readily run
+along a rope to reach the ship. Once infested, the ship must be
+thoroughly fumigated, not only to avoid carrying the disease to other
+ports but to obviate an outbreak on board.
+
+When an epidemic begins, rats must be destroyed by trapping and
+poisoning. Various so-called biological poisons have not proved
+practicable. Sources of food supply should be cut off by thorough
+cleaning up, by use of rat-proof garbage cans and similar measures. Hand
+in hand with these, must go the destruction of breeding places, and the
+rat-proofing of dwellings, stables, markets, warehouses, docks and
+sewers. All these measures are expensive, and a few years ago would have
+been thought wholly impossible to put into practice but now they are
+being enforced on a large scale in every fight against the disease.
+
+Rats and other rodents are regularly caught in the danger zone and
+examined for evidence of infection, for the sequence of the epizootic
+and of the human disease is now understood. In London, rats are
+regularly trapped and poisoned in the vicinity of the principal docks,
+to guard against the introduction of infected animals in shipping.
+During the past six years infected rats have been found yearly, thirteen
+having been found in 1912. In Seattle, Washington, seven infected rats
+were found along the water front in October, 1913, and infected ground
+squirrels are still being found in connection with the anti-plague
+measures in California.
+
+The procedure during an outbreak of the human plague was well
+illustrated by the fight in San Francisco. The city was districted, and
+captured rats, after being dipped in some fluid to destroy the fleas,
+were carefully tagged to indicate their source, and were sent to the
+laboratory for examination. If an infected rat was found, the officers
+in charge of the work in the district involved were immediately notified
+by telephone, and the infected building was subjected to a thorough
+fumigation. In addition, special attention was given to all the
+territory in the four contiguous blocks.
+
+By measures such as these, this dread scourge of the human race is being
+brought under control. Incidentally, the enormous losses due to the
+direct ravages of rats are being obviated and this alone would justify
+the expenditure many times over of the money and labor involved in the
+anti-rat measures.
+
+
+
+
+CHAPTER VII
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC ORGANISMS
+
+
+We now have to consider the cases in which the arthropod acts as the
+essential host of a pathogenic organism. In other words, cases in which
+the organism, instead of being passively carried or merely accidentally
+inoculated by the bite of its carrier, or vector, is taken up and
+undergoes an essential part of its development within the arthropod.
+
+[Illustration: 113. Dipylidium caninum. The double pored tapeworm of the
+dog.]
+
+In some cases, the sexual cycle of the parasite is undergone in the
+arthropod, which then serves as the _definitive_ or _primary host_. In
+other cases, it is the asexual stage of the parasite which is undergone,
+and the arthropod then acts as the _intermediate host_. This distinction
+is often overlooked and all the cases incorrectly referred to as those
+in which the insect or other arthropod acts as intermediate host.
+
+We have already emphasized that this is the most important way in which
+insects may transmit disease, for without them the particular organisms
+concerned could never complete their development. Exterminate the
+arthropod host and the life cycle of the parasite is broken, the disease
+is exterminated.
+
+As the phenomenon of alternation of generations, as exhibited by many of
+the parasitic protozoa, is a complicated one and usually new to the
+student, we shall first take up some of the grosser cases illustrated by
+certain parasitic worms. There is the additional reason that these were
+the first cases known of arthropod transmission of pathogenic organisms.
+
+
+INSECTS AS INTERMEDIATE HOSTS OF TAPEWORMS
+
+A number of tapeworms are known to undergo their sexual stage in an
+insect or other arthropod. Of these at least two are occasional
+parasites of man.
+
+_Dipylidium caninum_ (figs. 113 and 114), more generally known as
+_Taenia cucumerina_ or _T. elliptica_, is the commonest intestinal
+parasite of pet dogs and cats. It is occasionally found as a human
+parasite, 70 per cent of the cases reported being in young children.
+
+In 1869, Melnikoff found in a dog louse, _Trichodectes canis_, some
+peculiar bodies which Leuckart identified as the larval form of this
+tapeworm. The worm is, however, much more common in dogs and cats than
+is the skin parasite, and hence it appears that the _Trichodectes_ could
+not be the only intermediate host. In 1888, Grassi found that it could
+also develop in the cat and dog fleas, _Ctenocephalus felis_ and _C.
+canis_, and in the human flea, _Pulex irritans_.
+
+[Illustration: 114. Dipylidium caninum. Rostrum evaginated and
+invaginated. After Blanchard.]
+
+[Illustration: 115. Dipylidium caninum. Immature cysticercoid. After
+Grassi and Rovelli.]
+
+The eggs, scattered among the hairs of the dog or cat, are ingested by
+the insect host and in its body cavity they develop into pyriform
+bodies, about 300µ in length, almost entirely destitute of a bladder,
+but in the immature stage provided with a caudal appendage (fig. 115).
+Within the pear-shaped body (fig. 116) are the invaginated head and
+suckers of the future tapeworm. This larval form is known as a
+cysticercoid, in contradistinction to the bladder-like cysticercus of
+many other cestodes. It is often referred to in literature as
+_Cryptocystis trichodectis_ Villot.
+
+As many as fifty of the cysticercoids have been found in the body cavity
+of a single flea. When the dog takes up an infested flea or louse, by
+biting itself, or when the cat licks them up, the larvæ quickly develop
+into tapeworms, reaching sexual maturity in about twenty days in the
+intestine of their host. Puppies and kittens are quickly infested when
+suckling a flea-infested mother, the developing worms having been found
+in the intestines of puppies not more than five or six days old.
+
+[Illustration: 116. Dipylidium caninum. Cysticercoid. After Villet.]
+
+Infestation of human beings occurs only through accidental ingestion of
+an infested flea. It is natural that such cases should occur largely in
+children, where they may come about in some such way as illustrated in
+the accompanying figures 117 and 118.
+
+_Hymenolepis diminuta_, very commonly living in the intestine of mice
+and rats, is also known to occur in man. Its cysticercoid develops in
+the body cavity of a surprising range of meal-infesting insects. Grassi
+and Rovelli (abstract in Ransom, 1904) found it in the larvæ and adult
+of a moth, _Asopia farinalis_, in the earwig, _Anisolabis annulipes_,
+the Tenebrionid beetles _Akis spinosa_ and _Scaurus striatus_. Grassi
+considers that the lepidopter is the normal intermediate host. The
+insect takes up the eggs scattered by rats and mice. It has been
+experimentally demonstrated that man may develop the tapeworm by
+swallowing infested insects. Natural infection probably occurs by
+ingesting such insects with cereals, or imperfectly cooked foods.
+
+[Illustration: 117. One way in which Dipylidium infection in children
+may occur. After Blanchard.]
+
+_Hymenolepis lanceolata_, a parasite of geese and ducks, has been
+reported once for man. The supposed cysticercoid occurs in various small
+crustaceans of the family Cyclopidæ.
+
+[Illustration: 118. The probable method by which Dipylidium infection
+usually occurs.]
+
+Several other cestode parasites of domestic animals are believed to
+develop their intermediate stage in certain arthropods. Among these may
+be mentioned:
+
+_Choanotænia infundibulformis_, of chickens, developing in the house-fly
+(Grassi and Rovelli);
+
+_Davainea cesticillus_, of chickens, in some lepidopter or coleopter
+(Grassi and Rovelli);
+
+_Hymenolepis anatina_, _H. gracilis_, _H. sinuosa_, _H. coronula_ and
+_Fimbriaria fasciolaris_, all occurring in ducks, have been reported as
+developing in small aquatic crustaceans. In these cases, cysticercoids
+have been found which, on account of superficial characters, have been
+regarded as belonging to the several species, but direct experimental
+evidence is scant.
+
+
+ARTHROPODS AS INTERMEDIATE HOSTS OF NEMATODE WORMS
+
+
+FILARIASIS AND MOSQUITOES--A number of species of Nematode worms
+belonging to the genus _Filaria_, infest man and other vertebrates and
+in the larval condition are to be found in the blood. Such infestation
+is known as _filariasis_. The sexually mature worms are to be found in
+the blood, the lymphatics, the mesentery and subcutaneous connective
+tissue. In the cases best studied it has been found that the larval
+forms are taken up by mosquitoes and undergo a transformation before
+they can attain maturity in man.
+
+The larvæ circulating in the blood are conveniently designated as
+microfilariæ. In this stage they are harmless and only one species,
+_Filaria bancrofti_, appears to be of any great pathological
+significance at any stage.
+
+_Filaria bancrofti_ in its adult state, lives in the lymphatics of man.
+Though often causing no injury it has been clearly established that they
+and their eggs may cause various disorders due to stoppage of the
+lymphatic trunks (fig. 119). Manson lists among other effects, abscess,
+varicose groin glands, lymph scrotum, chyluria, and elephantiasis.
+
+The geographical distribution of this parasite is usually given as
+coextensive with that of elephantiasis, but it is by no means certain
+that it is the only cause of this disease and so actual findings of the
+parasites are necessary. Manson reports that it is "an indigenous
+parasite in almost every country throughout the tropical and subtropical
+world, as far north as Spain in Europe and Charlestown in the United
+States, and as far south as Brisbane in Australia." In some sections,
+fully 50 per cent of the natives are infested. Labredo (1910) found
+17.82 per cent infestation in Havana.
+
+[Illustration: 119. Elephantiasis in Man. From "New Sydenham Society's
+Atlas."]
+
+The larval forms of _Filaria bancrofti_ were first discovered in 1863,
+by Demarquay, in a case of chylous dropsy. They were subsequently noted
+under similar conditions, by several workers, and by Wücherer in the
+urine of twenty-eight cases of tropical chyluria, but in 1872 Lewis
+found that the blood of man was the normal habitat, and gave them the
+name _Filaria sanguinis hominis_. The adult worm was found in 1876 by
+Bancroft, and in 1877, Cobbold gave it the name _Filaria bancrofti_. It
+has since been found repeatedly in various parts of the lymphatic
+system, and its life-history has been the subject of detailed studies by
+Manson (1884), Bancroft (1899), Low (1900), Grassi and Noé (1900), Noé
+(1901) and Fülleborn (1910).
+
+The larvæ as they exist in the circulating blood, exhibit a very active
+wriggling movement, without material progression. They may exist in
+enormous numbers, as many as five or six hundred swarming in a single
+drop of blood. This is the more surprising when we consider that they
+measure about 300µ × 8µ, that is, their width is equal to the diameter
+of the red blood corpuscle of their host and their length over
+thirty-seven times as great.
+
+Their organs are very immature and the structure obscure. When they have
+quieted down somewhat in a preparation it may be seen that at the head
+end there is a six-lipped and very delicate prepuce, enclosing a short
+"fang" which may be suddenly exserted and retracted. Completely
+enclosing the larva is a delicate sheath, which is considerably longer
+than the worm itself. To enter into further details of anatomy is beyond
+the scope of this discussion and readers interested are referred to the
+work of Manson and of Fülleborn.
+
+One of the most surprising features of the habits of these larvæ is the
+periodicity which they exhibit in their occurrence in the peripheral
+blood. If a preparation be made during the day time there may be no
+evidence whatever of filarial infestation, whereas a preparation from
+the same patient taken late in the evening or during the night may be
+literally swarming with the parasites. Manson quotes Mackenzie as having
+brought out the further interesting fact that should a "filarial subject
+be made to sleep during the day and remain awake at night, the
+periodicity is reversed; that is to say, the parasites come into the
+blood during the day and disappear from it during the night." There have
+been numerous attempts to explain this peculiar phenomenon of
+periodicity but in spite of objections which have been raised, the most
+plausible remains that of Manson, who believes that it is an adaptation
+correlated with the life-habits of the liberating agent of the parasite,
+the mosquito.
+
+The next stages in the development of _Filaria nocturna_ occur in
+mosquitoes, a fact suggested almost simultaneously by Bancroft and
+Manson in 1877, and first demonstrated by the latter very soon
+thereafter. The experiments were first carried out with _Culex
+quinquefasciatus_ (= _fatigans_) as a host, but it is now known that a
+number of species of mosquitoes, both anopheline and culicine, may serve
+equally well.
+
+When the blood of an infested individual is sucked up and reaches the
+stomach of such a mosquito, the larvæ, by very active movements, escape
+from their sheaths and within a very few hours actively migrate to the
+body cavity of their new host and settle down primarily in the thoracic
+muscles. There in the course of sixteen to twenty days they undergo a
+metamorphosis of which the more conspicuous features are the formation
+of a mouth, an alimentary canal and a trilobed tail. At the same time
+there is an enormous increase in size, the larvæ which measured .3 mm.
+in the blood becoming 1.5 mm. in length. This developmental period may
+be somewhat shortened in some cases and on the other hand may be
+considerably extended. The controlling factor seems to be the one of
+temperature.
+
+The transformed larvæ then reenter the body cavity and finally the
+majority of them reach the interior of the labium (fig. 120). A few
+enter the legs and antennæ, and the abdomen, but these are wanderers
+which, it is possible, may likewise ultimately reach the labium, where
+they await the opportunity to enter their human host.
+
+It was formerly supposed that when the infested mosquito punctured the
+skin of man, the mature larvæ were injected into the circulation. The
+manner in which this occurred was not obvious, for when the insect feeds
+it inserts only the stylets, the labium itself remaining on the surface
+of the skin. Fülleborn has cleared up the question by showing that at
+this time the filariæ escape and, like the hookworm, actively bore into
+the skin of their new host.
+
+[Illustration: 120. Filaria in the muscles and labium of Culex. After
+Blanchard.]
+
+Once entered, they migrate to the lymphatics and there quickly become
+sexually mature. The full grown females measure 85-90 mm. in length by
+.24-.28 mm. in diameter, while the males are less than half this size,
+being about 40 mm. by .1 mm. Fecundation occurs and the females will be
+found filled with eggs in various stages of development, for they are
+normally viviparous.
+
+_Filaria philippinensis_ is reported by Ashburn and Craig (1907) as a
+common blood filaria in the Philippine Islands. As they describe it, it
+differs from _Filaria bancrofti_ primarily in that it does not exhibit
+periodicity. Its development has been found to occur in _Culex
+quinquefasciatus_, where it undergoes metamorphosis in about fourteen or
+fifteen days. There is doubt as to the species being distinct from
+_bancrofti_.
+
+Several other species occur in man and are thought to be transferred by
+various insects, among which have been mentioned Tabanidæ and
+tsetse-flies, but there is no experimental proof in support of such
+conjectures.
+
+_Filaria immitis_ is a dangerous parasite of the dog, the adult worm
+living in the heart and veins of this animal. It is one of the species
+which has been clearly shown to undergo its development in the mosquito,
+particularly in _Anopheles maculipennis_ and _Aedes calopus_ (=
+Stegomyia). The larval form occurs in the peripheral blood, especially
+at night. When taken up by mosquitoes they differ from _Filaria
+bancrofti_ in that they undergo their development in the Malpighian
+tubules rather than in the thoracic muscles. In about twelve days they
+have completed their growth in the tubules, pierce the distal end, and
+pass to the labium. This species occurs primarily in China and Japan,
+but is also found in Europe and in the United States. It is an
+especially favorable species for studying the transformations in the
+mosquito.
+
+[Illustration: 121. Dracunculus medinensis; female; mouth; embryo. After
+Bastian and Leuckart.]
+
+_Filariæ_ are also commonly found in birds, and in this country this is
+the most available source of laboratory material. We have found them
+locally (Ithaca, N. Y.) in the blood of over sixty per cent of all the
+crows examined, at any season of the year, and have also found them in
+English sparrows.
+
+In the crows, they often occur in enormous numbers, as many as two
+thousand having been found in a single drop of the blood of the most
+heavily infested specimen examined. For study, a small drop of blood
+should be mounted on a clean slide and the coverglass rung with vaseline
+or oil to prevent evaporation. In this way they can be kept for hours.
+
+Permanent preparations may be made by spreading out the blood in a film
+on a perfectly clean slide and staining. This is easiest done by
+touching the fresh drop of blood with the end of a second slide which is
+then held at an angle of about 45° to the first slide and drawn over it
+without pressure. Allow the smear to dry in the air and stain in the
+usual way with hæmatoxylin.
+
+
+OTHER NEMATODE PARASITES OF MAN AND ANIMALS DEVELOPING IN ARTHROPODS
+
+_Dracunculus medinensis_ (fig. 121), the so-called guinea-worm, is a
+nematode parasite of man which is widely distributed in tropical Africa,
+Asia, certain parts of Brazil and is occasionally imported into North
+America.
+
+The female worm is excessively long and slender, measuring nearly three
+feet in length and not more than one-fifteenth of an inch in diameter.
+It is found in the subcutaneous connective tissue and when mature
+usually migrates to some part of the leg. Here it pierces the skin and
+there is formed a small superficial ulcer through which the larvæ reach
+the exterior after bursting the body of the mother.
+
+[Illustration: 122. Cyclops, the intermediate host of Dracunculus.]
+
+Fedtschenko (1879) found that when these larvæ reach the water they
+penetrate the carapace of the little crustacean, _Cyclops_ (fig. 122).
+Here they molt several times and undergo a metamorphosis. Fedtschenko,
+in Turkestan, found that these stages required about five weeks, while
+Manson who confirmed these general results, found that eight or nine
+weeks were required in the cooler climate of England.
+
+Infection of the vertebrate host probably occurs through swallowing
+infested cyclops in drinking water. Fedtschenko was unable to
+demonstrate this experimentally and objection has been raised against
+the theory, but Leiper (1907), and Strassen (1907) succeeded in
+infesting monkeys by feeding them on cyclops containing the larvæ.
+
+_Habronema muscæ_ is a worm which has long been known in its larval
+stage, as a parasite of the house-fly. Carter found them in 33 per cent
+of the house-flies examined in Bombay during July, 1860, and since that
+time they have been shown to be very widely distributed. Italian workers
+reported them in 12 per cent to 30 per cent of the flies examined.
+Hewitt reported finding it rarely in England. In this country it was
+first reported by Leidy who found it in about 20 per cent of the flies
+examined at Philadelphia, Pa. Since then it has been reported by several
+American workers. We have found it at Ithaca, N. Y., but have not made
+sufficient examinations to justify stating percentage. Ransom (1913)
+reports it in thirty-nine out of one hundred and thirty-seven flies, or
+28 per cent.
+
+[Illustration: 123. An Echinorhynchid, showing the spinose retractile
+proboscis.]
+
+[Illustration: 124. June beetle (Lachnosterna).]
+
+[Illustration: Larva]
+
+Until very recently the life-history of this parasite was unknown but
+the thorough work of Ransom (1911, 1913) has shown clearly that the
+adult stage occurs in the stomach of horses. The embryos, produced by
+the parent worms in the stomach of the horse, pass out with the feces
+and enter the bodies of fly larvæ which are developing in the manure. In
+these they reach their final stage of larval development at about the
+time the adult flies emerge from the pupal stage. In the adult fly they
+are commonly found in the head, frequently in the proboscis, but they
+occur also in the thorax and abdomen. Infested flies are accidentally
+swallowed by horses and the parasite completes its development to
+maturity in the stomach of its definitive host.
+
+_Gigantorhynchus hirudinaceus_ (= _Echinorhynchus gigas_) is a common
+parasite of the pig and has been reported as occurring in man. The adult
+female is 20-35 cm. long and 4-9 mm. in diameter. It lacks an alimentary
+canal and is provided with a strongly spined protractile rostrum, by
+means of which it attaches to the intestinal mucosa of its host.
+
+The eggs are scattered with the feces of the host and are taken up by
+certain beetle larvæ. In Europe the usual intermediate hosts are the
+larvæ of the cockchafer, _Melolontha vulgaris_, or of the flower beetle,
+_Cetonia aurata_. Stiles has shown that in the United States the
+intermediate host is the larva of the June bug, _Lachnosterna_ (fig.
+124). It is probable that several of the native species serve in this
+capacity.
+
+A number of other nematode parasites of birds and mammals have been
+reported as developing in arthropods but here, as in the case of the
+cestodes, experimental proof is scant. The cases above cited are the
+better established and will serve as illustrations.
+
+
+
+
+CHAPTER VIII
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA
+
+
+MOSQUITOES AND MALARIA
+
+Under the name of malaria is included a group of morbid symptoms
+formerly supposed to be due to a miasm or bad air, but now known to be
+caused by protozoan parasites of the genus _Plasmodium_, which attack
+the red blood corpuscles. It occurs in paroxysms, each marked by a
+chill, followed by high fever and sweating. The fever is either
+intermittent or remittent.
+
+There are three principal types of the disease, due to different species
+of the parasite. They are:
+
+1. The benign-tertian, caused by _Plasmodium vivax_, which undergoes its
+schizogony or asexual cycle in the blood in forty-eight hours or even
+less. This type of the disease,--characterized by fever every two days,
+is the most wide-spread and common.
+
+2. The quartan fever is due to the presence of _Plasmodium malariæ_,
+which has an asexual cycle of seventy-two hours, and therefore the fever
+recurs every three days. This type is more prevalent in temperate and
+sub-tropical regions, but appears to be rare everywhere.
+
+3. The sub-tertian "æstivo-autumnal," or "pernicious" fever is caused by
+_Plasmodium falciparum_. Schizogony usually occurs in the internal
+organs, particularly in the spleen, instead of in the peripheral
+circulation, as is the case of the tertian and quartan forms. The fever
+produced is of an irregular type and the period of schizogony has not
+been definitely determined. It is claimed by some that the variations
+are due to different species of malignant parasites.
+
+It is one of the most wide-spread of human diseases, occurring in almost
+all parts of the world, except in the polar regions and in waterless
+deserts. It is most prevalent in marshy regions.
+
+So commonplace is malaria that it causes little of the dread inspired by
+most of the epidemic diseases, and yet, as Ross says, it is perhaps the
+most important of human diseases. Figures regarding its ravages are
+astounding. Celli estimated that in Italy it caused an average annual
+mortality of fifteen thousand, representing about two million cases. In
+India alone, according to Ross (1910) "it has been officially estimated
+to cause a mean annual death-rate of five per thousand; that is, to kill
+every year, on the average, one million one hundred and thirty
+thousand." In the United States it is widespread and though being
+restricted as the country develops, it still causes enormous losses.
+During the year 1911, "in Alabama alone there were seventy thousand
+cases and seven hundred and seventy deaths." The weakening effects of
+the disease, the invasion of other diseases due to the attacks of
+malaria, are among the very serious results, but they cannot be
+estimated.
+
+Not only is there direct effect on man, but the disease has been one of
+the greatest factors in retarding the development of certain regions.
+Everywhere pioneers have had to face it, and the most fertile regions
+have, in many instances been those most fully dominated by it. Herrick
+(1903) has presented an interesting study of its effects on the
+development of the southern United States and has shown that some parts,
+which are among the most fertile in the world, are rendered practically
+uninhabitable by the ravages of malaria. Howard (1909) estimates that
+the annual money loss from the disease in the United States is not less
+than $100,000,000.
+
+It was formerly supposed that the disease was due to a miasm, to a
+noxious effluvia, or infectious matter rising in the air from swamps. In
+other words its cause was, as the name indicated "mal aria," and the
+deep seated fear of night air is based largely on the belief that this
+miasm was given off at night. Its production was thought to be favored
+by stirring of the soil, dredging operations and the like.
+
+The idea of some intimate connection between malaria and mosquitoes is
+not a new one. According to Manson, Lancisi noted that in some parts of
+Italy the peasants for centuries have believed that malaria is produced
+by the bite of mosquitoes. Celli states that one not rarely hears from
+such peasants the statement that "In such a place, there is much fever,
+because it is full of mosquitoes." Koch points out that in German East
+Africa the natives call malaria and the mosquito by the same name,
+_Mbù_. The opinion was not lacking support from medical men. Celli
+quotes passages from the writings of the Italian physician, Lancisi,
+which indicate that he favored the view in 1717.
+
+Dr. Josiah Nott is almost universally credited with having supported the
+theory, in 1848, but as we have already pointed out his work has been
+misinterpreted. The statements of Beauperthuy, (1853) were more
+explicit.
+
+The clearest early presentation of the circumstantial evidence in favor
+of the theory of mosquito transmission was that of A. F. A. King, an
+American physician, in 1883. He presented a series of epidemiological
+data and showed "how they may be explicable by the supposition that the
+mosquito is the real source of the disease, rather than the inhalation
+or cutaneous absorption of a marsh vapor." We may well give the space to
+summarizing his argument here for it has been so remarkably
+substantiated by subsequent work:
+
+1. Malaria, like mosquitoes, affects by preference low and moist
+localities, such as swamps, fens, jungles, marshes, etc.
+
+2. Malaria is hardly ever developed at a lower temperature than 60°
+Fahr., and such a temperature is necessary for the development of the
+mosquito.
+
+3. Mosquitoes, like malaria, may both accumulate in and be obstructed by
+forests lying in the course of winds blowing from malarious localities.
+
+4. By atmospheric currents malaria and mosquitoes are alike capable of
+being transported for considerable distances.
+
+5. Malaria may be developed in previously healthy places by turning up
+the soil, as in making excavations for the foundation of houses, tracks
+for railroads, and beds for canals, because these operations afford
+breeding places for mosquitoes.
+
+6. In proportion as countries, previously malarious, are cleared up and
+thickly settled, periodical fevers disappear, because swamps and pools
+are drained so that the mosquito cannot readily find a place suitable to
+deposit her eggs.
+
+7. Malaria is most dangerous when the sun is down and the danger of
+exposure after sunset is greatly increased by the person exposed
+sleeping in the night air. Both facts are readily explicable by the
+mosquito malaria theory.
+
+8. In malarial districts the use of fire, both indoors and to those who
+sleep out, affords a comparative security against malaria, because of
+the destruction of mosquitoes.
+
+9. It is claimed that the air of cities in some way renders the poison
+innocuous, for, though a malarial disease may be raging outside, it does
+not penetrate far into the interior. We may easily conceive that
+mosquitoes, while invading cities during their nocturnal pilgrimages
+will be so far arrested by walls and houses, as well as attracted by
+lights in the suburbs, that many of them will in this way be prevented
+from penetrating "far into the interior."
+
+10. Malarial diseases and likewise mosquitoes are most prevalent toward
+the latter part of summer and in the autumn.
+
+11. Various writers have maintained that malaria is arrested by canvas
+curtains, gauze veils and mosquito nets and have recommended the rise of
+mosquito curtains, "through which malaria can seldom or never pass." It
+can hardly be conceived that these intercept marsh-air but they
+certainly do protect from mosquitoes.
+
+12. Malaria spares no age, but it affects infants much less frequently
+than adults, because young infants are usually carefully housed and
+protected from mosquito inoculation.
+
+Correlated with the miasmatic theory was the belief that some animal or
+vegetable organism which lived in marshes, produced malaria, and
+frequent searches were made for it. Salisbury (1862) thought this
+causative organism to be an alga, of the genus _Palmella_; others
+attributed it to certain fungi or bacteria.
+
+In 1880, the French physician, Laveran, working in Algeria, discovered
+an amœboid organism in the blood of malarial patients and definitely
+established the parasitic nature of this disease. Pigmented granules had
+been noted by Meckel as long ago as 1847, in the spleen and blood of a
+patient who had died of malaria, and his observations had been
+repeatedly verified, but the granules had been regarded as degeneration
+products, and the fact that they occurred in the body of a foreign
+organism had been overlooked.
+
+Soon after the discovery of the parasites in the blood, Gerhardt (1884)
+succeeded in transferring the disease to healthy individuals by
+inoculation of malarious blood, and thus proved that it is a true
+infection. This was verified by numerous experimenters and it was found
+that inoculation with a very minute quantity of the diseased blood would
+not only produce malaria but the particular type of disease.
+
+Laveran traced out the life cycle of the malarial parasite as it occurs
+in man. The details as we now know them and as they are illustrated by
+the accompanying figure 125, are as follows:
+
+The infecting organism or _sporozoite_, is introduced into the
+circulation, penetrates a red blood corpuscle, and forms the amœboid
+_schizont_. This lives at the expense of the corpuscle and as it
+develops there are deposited in its body scattered black or reddish
+black particles. These are generally called melanin granules, but are
+much better referred to as hæmozoin, as they are not related to
+melanin. The hæmozoin is the most conspicuous part of the parasite, a
+feature of advantage in diagnosing from unstained preparations.
+
+[Illustration: 125. Life cycle of the malaria parasite. Adapted from
+Leuckart's chart, by Miss Anna Stryke.]
+
+As the schizont matures, its nucleus breaks up into a number of daughter
+nuclei, each with a rounded mass of protoplasm about it, and finally the
+corpuscles are broken down and these rounded bodies are liberated in the
+plasma as _merozoites_. These merozoites infect new corpuscles and thus
+the asexual cycle is continued. The malarial paroxysm is coincident with
+sporulation.
+
+As early as Laveran's time it was known that under conditions not yet
+determined there are to be found in the blood of malarious patients
+another phase of the parasite, differing in form according to the type
+of the disease. In the pernicious type these appear as large,
+crescent-shaped organisms which have commonly been called "crescents."
+We now know that these are sexual forms.
+
+When the parasite became known there immediately arose speculations as
+to the way in which it was transferred from man to man. It was thought
+by some that in nature it occurred as a free-living amœba, and that
+it gained access to man through being taken up with impure water.
+However, numerous attempts to infect healthy persons by having them
+drink or inhale marsh water, or by injecting it into their circulation
+resulted in failure, and influenced by Leuckart's and Melnikoff's work
+on _Dipylidium_, that of Fedtschenko on _Dracunculus_, and more
+especially by that of Manson on _Filaria_, search was made for some
+insect which might transfer the parasite.
+
+Laveran had early suggested that the rôle of carrier might be played by
+the mosquito, but Manson first clearly formulated the hypothesis, and it
+was largely due to his suggestions that Ross in India, undertook to
+solve the problem. With no knowledge of the form or of the appearance in
+this stage, or of the species of mosquito concerned, Ross spent almost
+two and a half years of the most arduous work in the search and finally
+in August, 1897, seventeen years after the discovery of the parasite in
+man, he obtained his first definite clue. In dissecting a
+"dappled-winged mosquito," "every cell was searched and to my intense
+disappointment nothing whatever was found, until I came to the insect's
+stomach. Here, however, just as I was about to abandon the examination,
+I saw a very delicate circular cell, apparently lying amongst the
+ordinary cells of the organ and scarcely distinguishable from them. On
+looking further, another and another similar object presented itself. I
+now focused the lens carefully on one of these, and found that it
+contained a few minute granules of some black substance, exactly like
+the pigment of the parasite of malaria. I counted altogether twelve of
+these cells in the insect."
+
+Further search showed that "the contents of the mature pigment cells did
+not consist of clear fluid but of a multitude of delicate, thread-like
+bodies which on the rupture of the parent cell, were poured into the
+body cavity of the insect. They were evidently spores."
+
+With these facts established, confirmation and extension of Ross's
+results quickly followed, from many different sources. We cannot trace
+this work in detail but will only point out that much of the credit is
+due to the Italian workers, Grassi, Bignami, and Bastianelli, and to
+Koch and Daniels.
+
+It had already been found that when fresh blood was mounted and properly
+protected against evaporation, a peculiar change occurred in these
+crescents after about half an hour's time. From certain of them there
+were pushed out long whip-like processes which moved with a very active,
+lashing movement. The parasite at this stage is known as the
+"flagellated body." Others, differing somewhat in details of structure,
+become rounded but do not give off "flagella."
+
+The American worker, MacCallum (1897), in studying bird malaria as found
+in crows, first recognized the true nature of these bodies. He regarded
+them as sexual forms and believed that the so-called flagella played the
+part of spermatozoa. Thus, the "flagellated body" is in reality a
+_microgametoblast_, producing _microgametes_, or the male sexual
+element, while the others constitute the _macrogametes_, or female
+elements.
+
+It was found that when blood containing these sexual forms was sucked up
+by an Anopheline mosquito and taken into its stomach, a microgamete
+penetrated and fertilized a macrogamete in a way analogous to what takes
+place in the fertilization of the egg in higher forms. The resultant,
+mobile organism is known as the _migratory ookinete_. In this stage the
+parasite bores through the epithelial lining of the "stomach"
+(mid-intestine) of the mosquito and becomes encysted under the muscle
+layers. Here the _oocyst_, as it is now known, matures and breaks up
+into the body cavity and finally its products come to lie in the
+salivary glands of the mosquito. Ten to twelve days are required for
+these changes, after which the mosquito is infective, capable of
+introducing the parasite with its saliva, when feeding upon a healthy
+person.
+
+Thus the malarial parasite is known to have a double cycle, an
+alternation of generations, of which the asexual stage is undergone in
+man, the sexual in certain species of mosquitoes. The mosquito is
+therefore the definitive host rather than the _intermediate_, as usually
+stated.
+
+The complicated cycle may be made clearer by the diagram of Miss Stryke
+(1912) which, by means of a double-headed mosquito (fig. 126) endeavors
+to show how infection takes place through the biting of the human
+victim, (at A), in whom asexual multiplication then takes place, and how
+the sexual stages, taken up at B in the diagram, are passed in the body
+of the mosquito.
+
+[Illustration: 126. Life cycle of the malarial parasite. After Miss Anna
+Stryke.]
+
+The experimental proof that mosquitoes of the Anopheline group are
+necessary agents in the transmission of malaria was afforded in 1900
+when two English physicians, Drs. Sambon and Low lived for the three
+most malarial months in the midst of the Roman Campagna, a region
+famous for centuries as a hot-bed of malaria. The two experimenters
+moved about freely throughout the day, exposed themselves to rains and
+all kinds of weather, drank marsh water, slept exposed to the marsh air,
+and, in short, did everything which was supposed to cause malaria,
+except that they protected themselves thoroughly from mosquito bites,
+retiring at sunset to a mosquito-proof hut. Though they took no quinine
+and all of their neighbors suffered from malaria, they were absolutely
+free from the disease.
+
+To complete the proof, mosquitoes which had fed in Rome on malarious
+patients were sent to England and allowed to bite two volunteers, one of
+them Dr. Manson's own son, who had not been otherwise exposed to the
+disease. Both of these gentlemen contracted typical cases of malaria and
+the parasites were to be found in abundance in their blood.
+
+[Illustration: 127. Eggs of Anopheles. After Howard.]
+
+Since that time there have been many practical demonstrations of the
+fact that malaria is transmitted exclusively by the bite of mosquitoes
+and that the destruction of the mosquitoes means the elimination of the
+disease.
+
+We have said that the malarial parasite is able to undergo its
+development only in certain species of mosquitoes belonging to the
+Anopheline group. It is by no means certain that all of this group even,
+are capable of acting as the definitive host of the parasites, and much
+careful experiment work is still needed along this line. In the United
+States, several species have been found to be implicated, _Anopheles
+quadrimaculatus_ and _Anopheles crucians_ being the most common. The
+characteristics of these species and the distinctions between them and
+other mosquitoes will be discussed in Chapter XII.
+
+In antimalarial work it is desirable to distinguish the anopheline
+mosquitoes from the culicine species in all stages. The following
+tabulation presents the more striking distinctions between the groups as
+represented in the United States.
+
+_Anopheles_                             _Culex, Aedes, etc_.
+
+_Eggs_: Laid singly in small            Deposited in clumps in the
+numbers upon the surface of the         form of a raft (Culex group) or
+water. Eggs lie upon their sides        deposited singly in the water or
+and float by means of lateral           on the ground in places which
+expansions (fig. 127).                  may later be submerged.
+
+_Larva_: When at rest floats in         When at rest (with few exceptions)
+a horizontal position beneath the       floats suspended in an
+surface film. No respiratory            oblique or vertical position, or
+tube but instead a flattened            more rarely nearly horizontal,
+area on the eighth abdominal            with the respiratory tube in
+segment into which the two              contact with the surface film
+spiracles open (fig. 128).              (fig. 128).
+
+_Adults_: Palpi in both sexes           Palpi short in the female, in
+nearly or quite as long as the          the male usually elongate.
+proboscis. Proboscis projecting         Proboscis projects forward at an
+forward nearly on line with the         angle with the axis of the body.
+axis of the body. When at rest          When at rest on a vertical wall
+on a vertical wall the body is          the body is usually held parallel
+usually held at an angle with the       or the tip of the abdomen inclined
+vertical (fig. 128). Wings frequently   towards the wall (fig. 128).
+spotted (fig. 130).                     Wings usually not spotted.
+
+[Illustration: 128. (_a_) Normal position of the larvæ of Culex and
+Anopheles in the water. Culex, left; Anopheles, middle; Culex pupa,
+right hand figure.]
+
+These malarial-bearing species are essentially domesticated mosquitoes.
+They develop in any accumulation of water which stands for a week or
+more. Ponds, puddles, rain barrels, horse troughs, cess-pools, cans,
+even the foot-prints of animals in marshy ground may afford them
+breeding places.
+
+[Illustration: 128. (_b_) Normal position of Culex and Anopheles on the
+wall.]
+
+It is clear from what has been said regarding the life cycle of the
+malarial parasite that the mosquito is harmless if not itself diseased.
+Hence malarial-bearing species may abound in the neighborhood where
+there is no malaria, the disease being absent simply because the
+mosquitoes are uninfected. Such a locality is potentially malarious and
+needs only the introduction of a malarial patient who is exposed to the
+mosquitoes. It is found that such patients may harbor the parasites in
+their blood long after they are apparently well and thus may serve as a
+menace, just as do the so-called typhoid carriers. In some malarious
+regions as high as 80-90 per cent of the natives are such
+malaria-carriers and must be reckoned with in antimalaria measures.
+
+Based upon our present day knowledge of the life cycle of the malarial
+parasite the fight against the disease becomes primarily a problem in
+economic entomology,--it is a question of insect control, in its
+broadest interpretation.
+
+[Illustration: 129. Larva of Anopheles. After Howard.]
+
+The lines of defence and offence against the disease as outlined by
+Boyce (1909) are:
+
+  1. Measures to avoid the reservoir (man):
+
+    Segregation.
+
+    Screening of patients.
+
+  2. Measures to avoid Anopheles:
+
+    Choice of suitable locality, when possible.
+
+    Screening of houses and porches.
+
+    Sleeping under mosquito nets.
+
+  3. Measures to exterminate the Anopheles:
+
+    Use of natural enemies.
+
+    Use of culicides, oiling ponds, etc.
+
+    Drainage and scavenging to destroy breeding places.
+
+    Enforcement of penalties for harboring larvæ or keeping stagnant
+      water.
+
+    Educational methods.
+
+  4. Systematic treatment with quinine to exterminate the parasites.
+
+
+MOSQUITOES AND YELLOW FEVER
+
+Yellow fever was until recently one of the most dreaded of epidemic
+diseases. It is an acute, specific and infectious disease,
+non-contagious in character but occurring in epidemics, or endemics,
+within a peculiarly limited geographical area. It is highly fatal, but
+those who recover are generally immune from subsequent attacks.
+
+It is generally regarded as an American disease, having been found by
+Cortez, in Mexico, and being confined principally to the American
+continents and islands. It also occurs in Africa and attempts have been
+made to show that it was originally an African disease but there is not
+sufficient evidence to establish this view.
+
+There have been many noted outbreaks in the United States. Boston
+suffered from it in 1691 and again in 1693; New York in 1668 and as late
+as 1856; Baltimore in 1819. In 1793 occurred the great epidemic in
+Philadelphia, with a death rate of one in ten of the population. In the
+past century it was present almost every year in some locality of our
+Southern States, New Orleans being the greatest sufferer. In the latter
+city there were 7848 deaths from the disease in 1853, 4854 in 1858, and
+4046 in 1878. The last notable outbreak was in 1905. Reed and Carroll
+(1901) estimated that during the period from 1793 to 1900 there had not
+been less than 500,000 cases in the United States.
+
+[Illustration: 130. Anopheles quadrimaculatus, male and female,
+(×3½). After Howard.]
+
+As in the case of the plague, the most stringent methods of control
+proved ineffective and helplessness, almost hopelessness marked the
+great epidemics. A vivid picture of conditions is that given by Mathew
+Cary, 1793 (quoted by Kelly, 1906) in "A Short Account of the Malignant
+Fever Lately Prevalent in Philadelphia."
+
+[Illustration: 131. Anopheles punctipennis. Female, (×4). After Howard.]
+
+"The consternation of the people of Philadelphia at this period was
+carried beyond all bounds. Dismay and affright were visible in the
+countenance of almost every person. Of those who remained, many shut
+themselves in their houses and were afraid to walk the streets. * * *
+The corpses of the most respectable citizens, even those who did not die
+of the epidemic, were carried to the grave on the shafts of a chair
+(chaise), the horse driven by a negro, unattended by friends or
+relative, and without any sort of ceremony. People hastily shifted their
+course at the sight of a hearse coming toward them. Many never walked on
+the footpath, but went into the middle of the streets to avoid being
+infected by passing by houses wherein people had died. Acquaintances and
+friends avoided each other in the streets and only signified their
+regard by a cold nod. The old custom of shaking hands fell into such
+disuse that many shrunk back with affright at even the offer of the
+hand. A person with a crape, or any appearance of mourning was shunned
+like a viper. And many valued themselves highly on the skill and address
+with which they got to the windward of every person they met. Indeed, it
+is not probable that London, at the last stage of the plague, exhibited
+stronger marks of terror than were to be seen in Philadelphia from the
+24th or 25th of August until pretty late in September."
+
+[Illustration: 132. Anopheles crucians. Female (×4). After Howard.]
+
+Such was the condition in Philadelphia in 1793 and, as far as methods of
+control of the disease were concerned, there was practically no advance
+during the last century. The dominant theory was that yellow fever was
+spread by _fomites_, that is, exposed bedding, clothing, baggage, and
+the like. As late as 1898 a bulletin of the United States Marine
+Hospital Service stated:
+
+"While yellow fever is a communicable disease, it is not contagious in
+the ordinary acceptance of the term, but is spread by the infection of
+places and articles of bedding, clothing, and furniture."
+
+Based upon this theory, houses, baggage, freight, even mail, were
+disinfected, and the most rigid quarantine regulations were enforced.
+The hardships to which people of the stricken regions were subjected and
+the financial losses are incalculable. And withal, the only efficient
+check upon the disease seemed to be the heavy frosts. It was found that
+for some reason, the epidemic abated with cold weather,--a measure
+beyond human control.
+
+[Illustration: 133. Culex sollicitans. Female (×4). After Howard.]
+
+It is not strange that among the multitude of theories advanced to
+explain the cause and method of dissemination of the disease there
+should be suggestions that yellow fever was transmitted by the mosquito.
+We have seen that Beauperthuy (1855) clearly urged this theory.
+
+More detailed, and of the greatest influence in the final solution of
+the problem were the arguments of Dr. Cárlos Finlay, of Havana. In 1881,
+in a paper presented before the "Real Academia de Ciencias Médicas,
+Físicas y Naturales de la Habana," he said:
+
+"I feel convinced that any theory which attributes the origin and the
+propagation of yellow fever to atmospheric influences, to miasmatic or
+meteorological conditions, to filth, or to the neglect of general
+hygienic precautions, must be considered as utterly indefensible."
+
+He postulated the existence of a material transportable substance
+causing yellow fever,--"something tangible which requires to be conveyed
+from the sick to the healthy before the disease can be propagated" and
+after discussing the peculiarities of the spread of the disease and the
+influence of meteorological conditions, he decides that the carriers of
+the disease must be sought among insects. He continues:
+
+"On the other hand, the fact of yellow fever being characterized both
+clinically and (according to recent findings) histologically, by lesions
+of the blood vessels and by alterations of the physical and chemical
+conditions of the blood, suggested that the insect which should convey
+the infectious particles from the patient to the healthy should be
+looked for among those which drive their sting into blood vessels in
+order to suck human blood. Finally, by reason of other considerations
+which need not be stated here, I came to think that the mosquito might
+be the transmitter of yellow fever."
+
+"Assimilating the disease to small-pox and to vaccination, it occurred
+to me that in order to inoculate yellow fever it would be necessary to
+pick out the inoculable material from within the blood vessels of a
+yellow fever patient and to carry it likewise into the interior of a
+blood vessel of a person who was to be inoculated. All of which
+conditions the mosquito satisfies most admirably through its bite."
+
+In the course of his study of the problem, Finlay made detailed studies
+of the life history and habits of the common mosquitoes at Havana, and
+arrived at the conclusion that the carrier of the yellow fever was the
+_Culex mosquito_ or _Aëdes calopus_, as it is now known. With this
+species he undertook direct experimental tests, and believed that he
+succeeded in transmitting the disease by the bite of infected mosquitoes
+in three cases. Unfortunately, possibility of other exposure was not
+absolutely excluded, and the experiments attracted little attention.
+
+Throughout the next twenty years Finlay continued his work on yellow
+fever, modifying his original theory somewhat as time went on. Among his
+later suggestions was that in the light of Smith's work on Texas fever,
+his theory must be "somewhat modified so as to include the important
+circumstance that the faculty of transmitting the yellow fever germ need
+not be limited to the parent insect, directly contaminated by stinging a
+yellow fever patient (or perhaps by contact with or feeding from his
+discharges), but may be likewise inherited by the next generation of
+mosquitoes issued from the contaminated parent." He believed that the
+bite of a single mosquito produced a light attack of the disease and was
+thus effective in immunizing the patient. Throughout the period, many
+apparently successful attempts to transmit the disease by mosquitoes
+were made. In the light of present day knowledge we must regard these as
+defective not only because possibility of other infection was not
+absolutely excluded but because no account was taken of the incubation
+period within the body of the mosquito.
+
+In 1900, while the American army was stationed in Cuba there occurred an
+epidemic of yellow fever and an army medical board was appointed for
+"the purpose of pursuing scientific investigations with reference to the
+acute infectious diseases prevalent on the island." This was headed by
+Walter Reed and associated with him were James Carroll, Jesse W. Lazear
+and Aristides Agramonte, the latter a Cuban immune. For a detailed
+summary of this work the lay reader cannot do better than read Dr.
+Kelly's fascinating biography "Walter Reed and Yellow Fever."
+
+Arriving at the army barracks near Havana the Commission first took up
+the study of _Bacillus icteroides_, the organism which Sanarelli, an
+Italian physician, had declared the causative agent in yellow fever.
+They were unable to isolate this bacillus either from the blood during
+life or from the blood and organs of cadavers and therefore turned their
+attention to Finlay's theory of the propagation of yellow fever by means
+of the mosquito. In this work they had the unselfish and enthusiastic
+support of Dr. Finlay himself, who not only consulted with them and
+placed his publications at their disposal, but furnished eggs from which
+their experimental mosquitoes were obtained. Inoculations of eleven
+non-immunes through the bite of infected mosquitoes were made, and of
+these, two gave positive results. The first of the two was Dr. Carroll
+who allowed himself to be bitten by a mosquito which had been caused to
+feed upon four cases of yellow fever, two of them severe and two mild.
+The first patient had been bitten twelve days before.
+
+Three days after being bitten, Dr. Carroll came down with a typical case
+of yellow fever. So severe was the attack that for three days his life
+hung in the balance. During his convalescence an incident occurred which
+showed how the theory of mosquito transmission of the disease was
+generally regarded. We quote from Dr. Kelly: "One of his nurses who came
+from Tennessee had had considerable experience with yellow fever, having
+indeed, lost her husband and several children from it. One day early in
+his illness Dr. Carroll mentioned to her that he had contracted the
+disease through the bite of a mosquito, and noticed that she looked
+surprised. Some time later, when well enough to look over the daily
+records of his condition, he found this entry: 'Says he got his illness
+through the bite of a mosquito,--delirious'."
+
+The second case was that of an American who was bitten by four
+mosquitoes, two of which had bitten severe (fatal) cases of yellow fever
+twelve days previously, one of which had bitten a severe case (second
+day) sixteen days before and one which had bitten a severe case eight
+days before. Five days later, the subject developed a well pronounced
+but mild case of the disease.
+
+In the meantime, another member of the Commission, Dr. Lazear, was
+accidentally bitten by a mosquito while collecting blood from yellow
+fever patients. Five days later he contracted a typical case which
+resulted fatally.
+
+So clear was the evidence from these preliminary experiments that the
+commission felt warranted in announcing, October 27, 1900, that, "The
+mosquito serves as the intermediate host for the parasite of yellow
+fever, and it is highly probable that the disease is only propagated
+through the bite of this insect."
+
+In order to extend the experimental evidence under conditions which
+could leave no possibility of infection from other sources, a special
+experimental sanitary station, named in honor of the deceased member of
+the Commission, was established in an open field near the town of
+Quemados, Cuba. Here there were constructed two small buildings known
+respectively as the "infected clothing building" and the "infected
+mosquito building."
+
+The infected clothing building, 14 × 20 feet in size, was purposely so
+constructed as to exclude anything like efficient ventilation, but was
+thoroughly screened to prevent the entrance of mosquitoes. Into this
+building were brought sheets, pillow-slips, blankets, etc., contaminated
+by contact with cases of yellow fever and their discharges,--many of
+them purposely soiled with a liberal quantity of black vomit, urine, and
+fecal matter from patients sick with yellow fever. Nothing could better
+serve as the fomites which were supposed to convey the dread disease.
+
+Three non-immunes unpacked these articles, giving each a thorough
+handling and shaking in order to disseminate through the air of the room
+the specific agent of the disease. They were then used in making up the
+beds which the volunteers occupied each night for a period of twenty
+days. The experiment was repeated three times, volunteers even sleeping
+in the soiled garments of yellow fever victims but in not a single case
+was there the slightest symptom of disease. The theory of the spread of
+yellow fever by fomites was completely demolished.
+
+The infected mosquito building, equal in size to its companion, was the
+antithesis as far as other features were concerned. It was so
+constructed as to give the best possible ventilation, and bedding which
+was brought into it was thoroughly sterilized. Like the infected
+clothing building it was carefully screened, but in this case it was in
+order to keep mosquitoes in it as well as to prevent entrance of others.
+Through the middle of the room ran a mosquito-proof screen.
+
+On December 5, 1900, a non-immune volunteer who had been in the
+quarantine camp for fifteen days and had had no other possible exposure,
+allowed himself to be bitten by five mosquitoes which had fed on yellow
+fever patients fifteen or more days previously. The results were fully
+confirmatory of the earlier experiments of the Commission--at the end of
+three days, nine and a half hours, the subject came down with a well
+marked case of yellow fever.
+
+In all, ten cases of experimental yellow fever, caused by the bite of
+infected mosquitoes were developed in Camp Lazear. Throughout the period
+of the disease, other non-immunes slept in the little building,
+separated from the patient only by the mosquito-proof screen, but in no
+circumstances did they suffer any ill effects.
+
+It was found that a yellow fever patient was capable of infecting
+mosquitoes only during the first three or four days after coming down
+with the disease. Moreover, after the mosquito has bitten such a
+patient, a period of at least twelve days must elapse before the insect
+is capable of transmitting the disease.
+
+Once the organism has undergone its twelve day development, the mosquito
+may remain infective for weeks. In experiments of the Commission, two of
+the mosquitoes transmitted the disease to a volunteer fifty-seven days
+after their contamination. No other volunteers presenting themselves,
+one of these mosquitoes died the sixty-ninth and one the seventy-first
+day after their original contamination, without it being determined
+whether they were still capable of transmitting the disease.
+
+So carefully carried out was this work and so conclusive were the
+results that Dr. Reed was justified in writing:
+
+"Six months ago, when we landed on this island, absolutely nothing was
+known concerning the propagation and spread of yellow fever--it was all
+an unfathomable mystery--but today the curtain has been drawn--its mode
+of propagation is established and we know that a case minus mosquitoes
+is no more dangerous than one of chills and fever."
+
+The conclusions of the Commission were fully substantiated by numerous
+workers, notably Dr. Guiteras of the Havana Board of Health, who had
+taken a lively interest in the work and whose results were made known in
+1901, and by the Brazilian and French Commission at Sao Paulo, Brazil,
+in 1903.
+
+Throughout the work of the Army Commission and down to the present time
+many fruitless efforts have been made to discover the specific organism
+of yellow fever. It was clearly established that the claims of Sanarelli
+for _Bacillus icteroides_ were without foundation. It was found, too,
+that whatever the infective agent might be it was capable of passing
+through a Berkefeld filter and thus belongs to the puzzling group of
+"filterable viruses." It was further found that the virus was destroyed
+by heating up to 55° C for ten minutes. It is generally believed that
+the organism is a Protozoan.
+
+The question of the hereditary transmission of the yellow fever organism
+within the mosquito was left unsettled by the Army Commission, though,
+as we have seen, it was raised by Finlay. Marchoux and Simond, of the
+French Commission devoted much attention to this phase of the problem
+and basing their conclusions on one apparently positive case, they
+decided that the disease could be transmitted through the egg of an
+infected _Aëdes calopus_ to the second generation and thence to man. The
+conclusion, which is of very great importance in the control of yellow
+fever, has not been verified by other workers.
+
+Once clearly established that yellow fever was transmitted solely by
+mosquitoes, the question of the characteristics, habits, and
+geographical distribution of the insect carrier became of vital
+importance.
+
+_Aëdes calopus_, more commonly known as _Stegomyia fasciata_ or
+_Stegomyia calopus_ (fig. 134) is a moderate sized, rather strikingly
+marked mosquito. The general color is dark-brown or reddish-brown, but
+the thorax has a conspicuous broad, silvery-white curved line on each
+side, with two parallel median silvery lines. Between the latter there
+is a slender, broken line. The whole gives a lyre-shaped pattern to the
+thorax. The abdomen is dark with silvery-white basal bands and silvery
+white spots on each side of the abdominal segments. Legs black with
+rings of pure white at the base of the segments.
+
+Size of the female 3.3 to 5 mm.; male 3 to 4.5 mm.
+
+[Illustration: 134. The yellow fever mosquito (Aëdes calopus). (×7).
+After Howard.]
+
+It is preeminently a domesticated species, being found almost
+exclusively about the habitation of man. "Its long association with man
+is shown by many of its habits. It approaches stealthily from behind. It
+retreats upon the slightest alarm. The ankles and, when one is sitting
+at a table or desk, the underside of the hands and wrists are favorable
+points of attack. It attacks silently, whereas other mosquitoes have a
+piping or humming note. The warning sound has doubtless been suppressed
+in the evolutionary process of its adaptation to man. It is extremely
+wary. It hides whenever it can, concealing itself in garments, working
+into the pockets, and under the lapels of coats, and crawling up under
+the clothes to bite the legs. In houses, it will hide in dark corners,
+under picture moldings and behind the heads of old-fashioned bedsteads.
+It will enter closets and hide in the folds of garments."--Howard.
+
+It was claimed by the French Commission, and subsequently often stated
+in discussions of the relation of the mosquito to yellow fever that the
+mature _Aëdes calopus_ will bite only at night. If this were true it
+would be of the greatest importance in measures to avoid the disease.
+Unfortunately, the claim was illy founded and numerous workers have
+clearly established that the exact converse is more nearly true, this
+mosquito being pre-eminently a day species, feeding most actively in
+early morning, about sunrise, and late in the afternoon. On cloudy days
+it attacks at any time during the day. Thus there is peril in the
+doctrine that infected regions may be visited with perfect safety during
+the daytime and that measures to avoid the mosquito attack need be taken
+only at night.
+
+[Illustration: 135_a_. Aëdes calopus. Pupa. After Howard.]
+
+Dr. Finlay maintained that the adult, even when starved, would not bite
+when the temperature was below 23° C, but subsequent studies have shown
+that this statement needs modification. The French Commission, working
+at Rio de Janeiro, found that _Aëdes calopus_ would bite regularly at
+temperatures between 22° and 25° and that the optimum temperature was
+between 27° and 30° C, but their experiments led them to believe that it
+would bite in nature at a temperature as low as 17° C.
+
+The yellow fever mosquito breeds in cisterns, water barrels, pitchers
+and in the various water receptacles about the house. In our own
+Southern States it very commonly breeds in the above-ground cisterns
+which are in general use. Often the larvæ (fig. 135b) are found in
+flower vases, or even in the little cups of water which are placed under
+the legs of tables to prevent their being overrun by ants. They have
+been repeatedly found breeding in the holy water font in churches. In
+short, they breed in any collection of water in close proximity to the
+dwellings or gathering places of man.
+
+The life cycle under favorable conditions is completed in from twelve to
+fifteen days. These figures are of course very dependent upon the
+temperature. The Army Commission in Cuba found that the cycle might be
+completed in as brief a period as nine and a half days. Under less
+favorable conditions it may be greatly lengthened.
+
+The adults are long lived. We have seen that during the experimental
+work in Cuba specimens were kept in captivity for sixty-nine and
+seventy-one days, respectively, and that they were proved to retain
+their infectivity for at least fifty-seven days. Dr. Guiteras
+subsequently kept an infected adult for one hundred and fifty-four days.
+
+Low temperatures have a very great effect not only on development, but
+on the activity and even life of the adults. Long before the method of
+transmission of yellow fever was discovered it was well known that the
+epidemics were brought to a close by heavy frosts, and it is now known
+that this is due to the killing of the mosquitoes which alone could
+spread the disease.
+
+[Illustration: 135_b_. Aëdes calopus; larva. (×7). After Howard.]
+
+_Aëdes calopus_ has a very wide distribution since, as Howard says,
+being a domestic mosquito, having a fairly long life in the adult stage,
+and having the custom of hiding itself in the most ingenious ways, it is
+particularly subject to carriage for long distances on board vessels, in
+railway trains, even packed in baggage. In general, its permanent
+distribution is from 40 degrees north latitude to 40 degrees south
+latitude (Brumpt), in a belt extending around the world. In the United
+States it breeds in most of our Southern States.
+
+Thus, as in the case of malaria, there are many places where the insect
+carrier is abundant but where yellow fever does not occur. Such, for
+instance, are Hawaii, Australia and Asia. An outbreak may occur at any
+time that a patient suffering from the disease is allowed to enter and
+become a source of infection for the mosquitoes. In this connection
+various writers have called attention to the menace from the Panama
+Canal. When it is completed, it will allow of direct passage from
+regions where yellow fever is endemic and this will greatly increase the
+possibility of its introduction into these places where it is now
+unknown. The result, with a wholly non-immune population, would be
+appalling.
+
+On the other hand, there are places wholly outside of the normal range
+of _Aëdes calopus_ where the disease has raged. Such are New York,
+Boston, and even Philadelphia, which have suffered notable epidemics.
+These outbreaks have been due to the introduction of infected mosquitoes
+during the heat of summer, when they have not only conveyed the disease
+but have found conditions favorable for their multiplication. Or,
+uninfected mosquitoes have been thus accidentally brought in and
+developed in large numbers, needing then only the accidental
+introduction of cases of the disease to start an epidemic.
+
+Methods of control of various diseases have been revolutionized by the
+discovery that they were insect-borne, but in no other case has the
+change been as radical or the results as spectacular as in the case of
+yellow fever. The "shot-gun quarantine," the sufferings and horrors, the
+hopelessness of fighting absolutely blindly have given way to an
+efficient, clear-cut method of control, based upon the knowledge that
+the disease is carried from man to man solely by the mosquito, _Aëdes
+calopus_. The lines of defense and offense are essentially as follows:
+
+In the first place, when a case of yellow fever occurs, stringent
+precautions must be adopted to prevent the infection of mosquitoes and
+the escape of any already infected. This means that the patient must be
+removed to a mosquito-proof room, or ward beyond reach of the insects,
+and that the infected room must be thoroughly fumigated at once, to kill
+the mosquitoes hiding within it. All cracks and openings should be
+closed with strips of paper and fumigation with burning sulphur or
+pyrethrum carefully carried out.
+
+It should be remembered that if the first case noted is that of a
+resident rather than imported, it means that the mosquito carriers
+became infected more than two weeks before the case was diagnosed, for
+as we have seen, the germ must undergo a twelve-day period of
+development within its insect host. Therefore a careful search must be
+made for mild cases which, though unrecognized, may serve as foci for
+the spread of the disease.
+
+In face of a threatened epidemic one of the most essential measures is
+to educate the citizens and to gain their complete coöperation in the
+fight along modern lines. This may be done through the schools, the
+pulpit, places of amusement, newspapers and even bulletin boards.
+
+Emphasis should be placed on the necessity of both non-immunes and
+immunes using mosquito curtains, and in all possible ways avoiding
+exposure to the mosquitoes.
+
+Then the backbone of the fight must be the anti-mosquito measures. In
+general, these involve screening and fumigating against adults, and
+control of water supply, oiling, and drainage against the larvæ. The
+region involved must be districted and a thorough survey undertaken to
+locate breeding places, which must, if possible, be eradicated. If they
+are necessary for water supplies, such as casks, or cisterns, they
+should be carefully screened to prevent access of egg-laying adults.
+
+The practical results of anti-mosquito measures in the fight against
+yellow fever are well illustrated by the classic examples of the work in
+Havana, immediately following the discoveries of the Army Commission and
+by the stamping out of the New Orleans epidemic in 1905.
+
+The opportunities for an immediate practical application of the theories
+of the Army Commission in Havana were ideal. The city had always been a
+hotbed of yellow fever and was the principal source from which the
+disease was introduced year after year into our Southern States. It was
+under martial law and with a military governor who was himself a
+physician and thoroughly in sympathy with the views of the Commission,
+the rigid enforcement of the necessary regulations was possible. The
+story of the first campaign has been often told, but nowhere more
+clearly than in Dr. Reed's own account, published in the _Journal of
+Hygiene_ for 1902.
+
+Closer home was the demonstration of the efficacy of these measures in
+controlling the yellow fever outbreak in New Orleans in 1905. During the
+spring and early summer of the year the disease had, unperceived, gained
+a firm foothold in that city and when, in early July the local Board of
+Health took cognizance of its existence, it was estimated that there had
+been in the neighborhood of one hundred cases.
+
+Conditions were not as favorable as they had been under martial law in
+Havana for carrying on a rigid fight along anti-mosquito lines. The
+densely populated city was unprepared, the public had to be educated,
+and an efficient organization built up. The local authorities actively
+began a general fight against the mosquito but in spite of their best
+efforts the disease continued to spread. It was recognized that more
+rigid organization was needed and on August 12th the United States
+Public Health and Marine Hospital Service was put in absolute charge of
+the fight. Up to this time there had been one hundred and forty-two
+deaths from a total of nine hundred and thirteen cases and all of the
+conditions seemed to threaten an outbreak to exceed the memorable one of
+1878 when, as we have seen there were four thousand and forty-six
+deaths.
+
+With the hearty coöperation of the citizens,--physicians and laymen
+alike,--the fight was waged and long before frost or any near approach
+thereto the disease was stamped out,--a thing unheard of in previous
+epidemics. The total loss of life was four hundred and sixty--about 11
+per cent as great as that from the comparable epidemic of 1878. If the
+disease had been promptly recognized and combated with the energy which
+marked the fight later in the summer, the outbreak would have made
+little headway and the great proportion of these lives would have been
+saved.
+
+
+
+
+CHAPTER IX
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA (Continued)
+
+
+INSECTS AND TRYPANOSOMIASES
+
+By trypanosomiasis is meant a condition of animal parasitism, common to
+man and the lower animals, in which trypanosomes, peculiar flagellate
+protozoa, infest the blood. Depending upon the species, they may be
+harmless, producing no appreciable ill-effect, or pathogenic, giving
+rise to conditions of disease. A number of these are known to be
+transferred by insects.
+
+In order that we may consider more fully the developmental stage of
+these parasites within their insect host, it is necessary that we
+describe briefly the structure of the blood-inhabiting stage.
+
+[Illustration: 136. Trypanosoma brucei. After Bruce.]
+
+The trypanosomes are elongated, usually pointed, flagellated protozoa
+(fig. 136) in which the single flagellum, bent under the body, forms the
+outer limit of a delicate undulating membrane. It arises near one end of
+the organism from a minute centrosome-like body which is known as the
+blepheroplast, and at the opposite end extends for a greater or less
+distance as a free flagellum. Enclosing, or close beside the
+blepheroplast is the small kinetonucleus. The principal nucleus, round
+or oval in form, is situated near the center of the body. Asexual
+reproductions occurs in this stage, by longitudinal fission, the nucleus
+and the blepheroplast dividing independently of one another. From the
+blepheroplast of one of the daughter cells a new flagellum is formed.
+
+Among the pathogenic species are to be found the causative organisms of
+some of the most serious diseases of domestic animals and even of man.
+It is probable that these pathogenic species secrete a specific poison.
+The majority of them are tropical in distribution.
+
+Though we are concerned especially with the species which infest man, we
+shall first consider two of the trypanosomes of lower animals, known
+long before any of those of man had been found.
+
+
+FLEAS AND LICE AS CARRIERS OF TRYPANOSOMA LEWISI.--_Trypanosoma lewisi_,
+the first mammalian trypanosome known, is to be found in the blood of
+wild rats. Like its host, it appears to be cosmopolitan in distribution,
+having been reported from several localities in the United States,
+Brazil, Argentine, England, Germany, France, Italy, Russia, Asia and
+Africa.
+
+This species is usually regarded as non-pathogenic, but in experimental
+work, especially with white rats, heavy infestations often result
+fatally, and naturally infested specimens sometimes show evidence of
+injury. Rats which have been infested exhibit at least temporary
+immunity against new infection.
+
+_Trypanosoma lewisi_ is transmitted from rat to rat by fleas and by
+lice. Rabinowitsch and Kempner (1899) first found that healthy rats
+which were kept with infested rats, showed trypanosomes in their blood
+after about two weeks. They found the trypanosomes in the alimentary
+canal of fleas which had fed on the diseased rats. On teasing such fleas
+in physiological salt solution and inoculating them into fresh rats they
+were able to produce the infection. Finally, they showed that the fleas
+which had fed upon infested rats were able to carry the parasites to
+healthy rats. Corresponding experiments with lice were not successful.
+Prowazek (1905) found in the rat louse (_Hæmatopinus spinulosus_)
+organisms which he regarded as developmental stages of the _Trypanosoma
+lewisi_. He believed that the sexual cycle was undergone in this insect.
+
+Nuttall (1908) readily transmitted the trypanosomes through the agency
+of fleas, (_Ceratophyllus fasciatus_ and _Ctenopthalmus agyrtes_). He
+believes that these insects are probably the chief transmitters of the
+parasite. He was also able to transmit it from diseased to healthy rats
+through the agency of the rat louse. He was unable to trace any
+developmental stages in the louse and inclined to the opinion that
+Prowazek was deceived by the presence of extraneous flagellates such as
+are known to exist in a number of blood-sucking arthropods.
+
+Nuttall concludes that since three distinct kinds of blood-sucking
+insects are capable of transmitting _Trypanosoma lewisi_ it appears
+doubtful that this flagellate is a parasite of the invertebrate "host"
+in the sense claimed by Prowazek and other investigators.
+
+
+TSETSE-FLIES AND NAGANA--One of the greatest factors in retarding the
+development of certain regions of Africa has been the presence of a
+small fly, little larger than the common house-fly. This is the
+tsetse-fly, _Glossina morsitans_ (fig. 165) renowned on account of the
+supposed virulence of its bite for cattle, horses and other domestic
+mammals.
+
+The technical characteristics of the tsetse-flies, or Glossinas, and
+their several species, will be found in a later chapter. We need
+emphasize only that they are blood-sucking Muscidæ and that, unlike the
+mosquitoes, the sexes resemble each other closely in structure of the
+mouth-parts, and in feeding habits.
+
+In 1894, Colonel David Bruce discovered that the fly was not in itself
+poisonous but that the deadly effect of its bite was due to the fact
+that it transmitted a highly pathogenic blood parasite, _Trypanosoma
+brucei_. This trypanosome Bruce had discovered in the blood of South
+African cattle suffering from a highly fatal disease known as "nagana".
+On inoculating the blood of infected cattle into horses and dogs he
+produced the disease and found the blood teeming with the causative
+organism. In the course of his work he established beyond question that
+the "nagana" and the tsetse-fly disease were identical.
+
+Tsetse-flies of the species _Glossina morsitans_, which fed upon
+diseased animals, were found capable of giving rise to the disease in
+healthy animals up to forty-eight hours after feeding. Wild tsetse-flies
+taken from an infected region to a region where they did not normally
+occur were able to transmit the disease to healthy animals. It was found
+that many of the wild animals in the tsetse-fly regions harbored
+_Trypanosoma brucei_ in their blood, though they showed no evidence of
+disease. As in the case of natives of malarial districts, these animals
+acted as reservoirs of the parasite. Non-immune animals subjected to the
+attacks of the insect carrier, quickly succumbed to the disease.
+
+A question of prime importance is as to whether the insect serves as an
+essential host of the pathogenic protozoan or whether it is a mere
+mechanical carrier. Bruce inclined to the latter view. He was unable to
+find living trypanosomes in the intestines or excrements of the fly or
+to produce the disease on the many occasions when he injected the
+excrement into healthy animals. Moreover, he had found that the
+experimental flies were infective only during the first forty-eight
+hours and that if wild flies were taken from the infected region, "kept
+without food for three days and then fed on a healthy dog, they never
+gave rise to the disease."
+
+Koch had early described what he regarded as sexual forms from the
+intestine of the fly but it remained for Kleine (1909) to experimentally
+demonstrate that a part of the life cycle of the parasite was undergone
+in the fly. Working with _Glossina palpalis_, he found that for a period
+of ten days or longer after feeding on an animal suffering from nagana
+it was non-infective, but that then it became infective and was able to
+transmit the disease for weeks thereafter. He discovered and described
+developmental stages of the parasite within the intestine of the insect.
+In other words, the tsetse-fly (in nature, _Glossina morsitans_), serves
+as an essential host, within which an important part of the life cycle
+of the parasite is undergone. These conclusions were quickly verified by
+Bruce and numerous other workers and are no longer open to question.
+Klein and Taute are even inclined to think that mechanical transmission
+plays practically no rôle in nature, unless the fly is interrupted while
+feeding and passes immediately to a new animal.
+
+
+TSETSE-FLIES AND SLEEPING SICKNESS OF MAN--About the beginning of the
+present century a hitherto little known disease of man began to attract
+great attention on account of its ravages in Uganda and the region of
+Victoria Nyanza in South Africa. It was slow, insiduous and absolutely
+fatal, characterized in its later stages by dullness, apathy, and
+finally absolute lethargy all day long, symptoms which gave it the name
+of "sleeping sickness."
+
+It was soon found that the disease was not a new one but that it had
+been known for over a hundred years on the west coast of Africa. Its
+introduction into Central and East Africa and its rapid spread have been
+attributed primarily to the development of the country, the formation of
+new trade routes and the free mingling of native tribes formerly
+isolated. It is estimated that in the first ten years of the present
+century there were approximately two hundred thousand deaths from the
+disease in the Uganda protectorate. In the British province Bugosa, on
+the Victoria Nyanza there were thirty thousand deaths in the period from
+1902-1905.
+
+While the disease is peculiarly African there are a number of instances
+of its accidental introduction into temperate regions. Slaves suffering
+from it were occasionally brought to America in the early part of the
+last century and cases have sometimes been imported into England. In
+none of the cases did the disease gain a foothold or spread at all to
+other individuals.
+
+In 1902 Dutton described a trypanosome, _T. gambiense_, which he and
+Forde had found the year before in the blood of a patient suffering from
+a peculiar type of fever in Gambia. In 1902-1903 Castellani found the
+same parasite in the cerebro-spinal fluid of sleeping-sickness patients
+and definitely reported it as the causative organism of the disease. His
+work soon found abundant confirmation, and it was discovered that the
+sleeping sickness was but the ultimate phase of the fever discovered by
+Dutton and Forde.
+
+When Castellani made known his discovery of the trypanosome of sleeping
+sickness, Brumpt, in France, and Sambon, in England, independently
+advanced the theory that the disease was transmitted by the tsetse-fly,
+_Glossina palpalis_. This theory was based upon the geographical
+distribution and epidemiology of the disease. Since then it has been
+abundantly verified by experimental evidence.
+
+Fortunately for the elucidation of problems relating to the methods of
+transfer of sleeping sickness, _Trypanosoma gambiense_ is pathogenic for
+many species of animals. In monkeys it produces symptoms very similar to
+those caused in man. Bruce early showed that _Glossina palpalis_ "fed on
+healthy monkeys eight, twelve, twenty-four and forty-eight hours after
+having fed on a native suffering from trypanosomiasis, invariably
+transmitted the disease. After three days the flies failed to transmit
+it." In his summary in Osler's Modern Medicine, he continues "But this
+is not the only proof that these flies can carry the infective agent. On
+the lake shore there was a large native population among whom we had
+found about one-third to be harboring trypanosomes in their blood. The
+tsetse-flies caught on this lake shore, brought to the laboratory in
+cages, and placed straightway on healthy monkeys, gave them the disease
+in every instance, and furnished a startling proof of the danger of
+loitering along the lake shore among those infected flies."
+
+As in the case of nagana, Bruce and most of the earlier investigators
+supposed the transmission of the sleeping sickness trypanosome by
+_Glossina palpalis_ to be purely mechanical. The work of Kleine (1909)
+clearly showed that for _Trypanosoma gambiense_ as well as for
+_Trypanosoma brucei_ the fly served as an essential host. Indeed, Kleine
+and many subsequent investigators are inclined to think that there is
+practically no mechanical transmission of trypanosomes from animal to
+animal by _Glossina_ in nature, and that the many successful experiments
+of the earlier investigators were due to the fact that they used wild
+flies which already harbored the transformed parasite rather than
+directly inoculated it from the blood of the diseased experimental
+animals. While the criticism is applicable to some of the work, this
+extreme view is not fully justified by the evidence at hand.
+
+Kleine states (1912) that _Glossina palpalis_ can no longer be regarded
+as the sole transmitter of sleeping sickness. Taute (1911) had shown
+that under experimental conditions _Glossina morsitans_ was capable of
+transferring the disease and Kleine calls attention to the fact that in
+German East Africa, in the district of the Rovuma River, at least a
+dozen cases of the disease have occurred recently, though only _Glossina
+morsitans_ exists in the district. It appears, however, that these cases
+are due to a different parasite, _Trypanosoma rhodesiense_. This
+species, found especially in north-east Rhodesia and in Nyassaland, is
+transferred by _Glossina morsitans_.
+
+Other workers maintain that the disease may be transmitted by various
+blood-sucking flies, or even bugs and lice which attack man. Fülleborn
+and Mayer (1907) have shown by conclusive experiments that _Aedes
+(Stegomyia) calopus_ may transmit it from one animal to another if the
+two bites immediately succeed each other.
+
+It is not possible that insects other than the tsetse-flies (and only
+certain species of these), play an important rôle in the transmission of
+the disease, else it would be much more wide-spread. Sambon (1908)
+pointed out that the hypothesis that is spread by _Aedes calopus_ is
+opposed by the fact that the disease never spread in the Antilles,
+though frequently imported there by West African slaves. The same
+observation would apply also to conditions in our own Southern States in
+the early part of the past century.
+
+Since _Glossina palpalis_ acts as an essential host of the parasite and
+the chief, if not the only, transmitter, the fight against sleeping
+sickness, like that against malaria and yellow fever, becomes primarily
+a problem in economic entomology. The minutest detail of the
+life-history, biology, and habits of the fly, and of its parasites and
+other natural enemies becomes of importance in attempts to eradicate the
+disease. Here we can consider only the general features of the subject.
+
+_Glossina palpalis_ lives in limited areas, where the forest and
+undergrowth is dense, along the lake shore or river banks. According to
+Hodges, the natural range from shore is under thirty yards, though the
+distance to which the flies may follow man greatly exceed this.
+
+It is a day feeder, a fact which may be taken advantage of in avoiding
+exposure to its attacks. The young are brought forth alive and
+full-grown, one every nine or ten days. Without feeding, they enter the
+ground and under favorable conditions, complete their development in a
+month or more.
+
+[Illustration: 137. Sleeping sickness concentration camp in German East
+Africa. Report of German Commission.]
+
+Methods of control of the disease must look to the prevention of
+infection of the flies, and to their avoidance and destruction. Along
+the first line, much was hoped from temporary segregation of the sick in
+regions where the fly was not found. On the assumption that the flies
+acted as carriers only during the first two or three days, it was
+supposed that even the "fly belts" would become safe within a few days
+after the sick were removed. The problem was found to be a much more
+difficult one when it was learned that after a given brief period the
+fly again became infective and remained so for an indeterminate period.
+Nevertheless, isolation of the sick is one of the most important
+measures in preventing the spread of the disease into new districts.
+Much, too, is being accomplished by moving native villages from the fly
+belts. (c.f. fig. 137.)
+
+All measures to avoid the flies should be adopted. This means locating
+and avoiding the fly belts as far as possible, careful screening of
+houses, and protection of the body against bites.
+
+Clearing the jungle along the water courses for some yards beyond the
+natural range of the fly has proved a very important measure. Castellani
+recommends that the area be one hundred yards and around a village three
+hundred yards at least.
+
+Detailed studies of the parasites and the natural enemies of the
+tsetse-fly are being undertaken and may ultimately yield valuable
+results.
+
+
+SOUTH AMERICAN TRYPANOSOMIASIS--The tsetse-flies are distinctively
+African in distribution and until recently there were no trypanosomes
+known to infest man in America. In 1909 Dr. Chagas, of Rio de Janeiro
+described a new species, _Trypanosoma cruzi_, pathogenic to man.
+
+_Trypanosoma cruzi_ is the causative organism of a disease common in
+some regions of Brazil, where it is known as "opilacao." It is
+especially to be met with in children and is characterized by extreme
+anemia, wasting, and stunted development associated with fever, and
+enlargement of the thyroid glands. The disease is transmitted by the
+bites of several species of assassin-bugs, or Reduviidæ, notably by
+_Conorhinus megistus_. The evolution of the parasite within the bug has
+been studied especially by Chagas and by Brumpt. From the latter's text
+we take the following summary.
+
+The adult trypanosomes, ingested by a _Conorhinus megistus_, of any
+stage, first change into Crithidia-like forms and then those which
+remain in the stomach become ovoid and non-motile. Brumpt found these
+forms in immense numbers, in a _Conorhinus_ which had been infested
+fourteen months before. The forms which pass into the intestine quickly
+assume the _Crithidia_ form and continue to develop rapidly under this
+form. Some weeks later they evolve into the trypanosome forms,
+pathogenic for man. They then pass out with the excrement of the bug and
+infect the vertebrate host as soon as they come in contact with any
+mucous layer (buccal, ocular or rectal). More rarely they enter through
+the epidermis.
+
+Brumpt showed that the development could take place in three species;
+bed-bugs (_Cimex lectularius_, _C. hemipterus_) and in the tick
+_Ornithodoros moubata_. The evolution proceeds in the first two species
+of bed-bugs as rapidly as in Conorhinus, or even more rapidly, but they
+remain infective for a much shorter time and hence Brumpt considers that
+they play a much less important rôle in the spread of the disease.
+
+_Conorhinus megistus_, like related forms in our Southern States, very
+commonly frequents houses and attacks man with avidity. Chagas states
+that the bites are painless and do not leave any traces. They are
+usually inflicted on the lips, or the cheeks and thus the buccal mucosa
+of a sleeper may be soiled by the dejections of the insect and the bite
+serving as a port of entry of the virus, remain unnoticed.
+
+The possibility of some of our North American Reduviidæ playing a
+similar rôle in the transmission of disease should not be overlooked.
+
+
+LEISHMANIOSES AND INSECTS--Closely related to the trypanosomes is a
+group of intracellular parasites which have recently been grouped by
+Ross under the genus _Leishmania_. Five species are known to affect man.
+Three of these produce local skin infestations, but two of them,
+_Leishmania donovani_ and _L. infantum_, produce serious and often fatal
+systemic diseases.
+
+The first of these, that produced by _L. donovani_, is an exceedingly
+virulent disease common in certain regions of India and China. It is
+commonly known as "Kala-azar," or "dum-dum" fever, and more technically
+as tropical leishmaniasis. Patton (1907) believes that the parasite is
+transmitted by the bed-bug _Cimex hemipterus_, and has described a
+developmental cycle similar to that which can be found in artificial
+cultures. On the other hand, Donovan was unable to confirm Patton's work
+and believes that the true intermediate host is a Reduviid bug,
+_Conorhinus rubrofasciatus_.
+
+_Leishmania infantum_ is the cause of the so-called infantile splenic
+leishmaniasis, occurring in northern Africa, Spain, Portugal, Italy, and
+possibly other parts of Europe. The parasite occurs habitually in the
+dog and is only accidentally transferred to children. Alvares and da
+Silva, in Portugal (according to Brumpt, 1913) have found that the
+excrement of a flea from a diseased dog contains flagellates, and they
+suggest that the infection may be transmitted by the accidental
+inoculation of this excrement by means of the proboscis of the flea, as
+has been thought to occur in the case of the plague. To this Brumpt
+objects that they and other workers who thought to trace the development
+of _Leishmania infantum_ were apparently misled by the presence of a
+harmless _Herpetomonas_ which infests dog fleas in all countries, even
+where the leishmaniasis is unknown.
+
+Basile (1910 and 1911) however, carried on numerous experiments
+indicating that the disease was transferred from children to dogs and
+from dog to dog by the dog flea, and was able to find in the tissues of
+the insects forms perfectly identical with those found in children and
+in dogs suffering from leishmaniasis. He also found that _Pulex
+irritans_ was capable of acting as the carrier.
+
+Of the cutaneous type of leishmaniasis, the best known is the so-called
+"Oriental sore," an ulcerative disease of the skin which is epidemic in
+many tropical and subtropical regions. The causative organism is
+_Leishmania tropica_, which occurs in the diseased tissues as bodies
+very similar to those found in the spleen in cases of Kala-azar. The
+disease is readily inoculable and there is no doubt that it may be
+transferred from the open sores to abraded surfaces of a healthy
+individual by house-flies. It is also believed by a number of
+investigators that it may be transferred and directly inoculated by
+various blood-sucking insects.
+
+
+TICKS AND DISEASES OF MAN AND ANIMALS
+
+We have seen that the way to the discoveries of the relations of
+arthropods to disease was pointed out by the work of Leuckart and
+Melnikoff on the life cycle of _Dipylidium_, and of Fedtschenko and
+Manson on that of _Filaria_. They dealt with grosser forms, belonging to
+well-recognized parasitic groups.
+
+This was long before the rôle of any insect as a carrier of pathogenic
+micro-organisms had been established, and before the Protozoa were
+generally regarded as of importance in the causation of disease. The
+next important step was taken in 1889 when Smith and Kilbourne
+conclusively showed that the so-called Texas fever of cattle, in the
+United States, is due to an intracorpuscular blood parasite transmitted
+exclusively by a tick. This discovery, antedating by eight years the
+work on the relation of the mosquito to malaria, had a very great
+influence on subsequent studies along these lines.
+
+While much of the recent work has dealt with the true insects, or
+hexapods, it is now known that several of the most serious diseases of
+animals, and at least two important diseases of man are tick borne.
+These belong to the types known collectively as _babesioses_ (or
+"_piroplasmoses_"), and _spirochætoses_.
+
+The term _babesiosis_ is applied to a disease of man or animals which is
+caused by minute protozoan parasites of the genus _Babesia_, living in
+the red blood corpuscles. These parasites have usually been given the
+generic name _Piroplasma_ and hence the type of disease which they cause
+is often referred to as "_piroplasmosis_." The best known illustration
+is the disease known in this country as Texas fever of cattle.
+
+
+CATTLE TICKS AND TEXAS FEVER--The cattle disease, which in the United
+States is known as Texas fever, is a widely distributed, exceedingly
+acute disease. In Australia it is known as _redwater fever_ and in
+Europe as hæmoglobinuria, due to the fact that the urine of the diseased
+animals is discolored by the breaking down of the red blood corpuscles
+infested by the parasite.
+
+In their historical discussion, Smith and Kilbourne, point out that as
+far back as 1796 it was noted that Southern cattle, in a state of
+apparent health, might spread a fatal disease among Northern herds. As
+observations accumulated, it was learned that this infection was carried
+only during the warm season of the year and in the depth of winter
+Southern cattle were harmless. Moreover, Southern cattle after remaining
+for a short time in the North lost their power to transmit the disease,
+and the same was true of cattle which had been driven for a considerable
+distance.
+
+Very significant was the fact that the infection was not communicated
+directly from the Southern to Northern cattle but that the ground over
+which the former passed was infected by them, and that the infection was
+transmitted thence to susceptible cattle _after a period of not less
+than thirty days had elapsed_.
+
+Of course a disease as striking as this, and which caused such enormous
+losses of cattle in the region invaded was fruitful in theories
+concerning its causation. The most widespread was the belief that
+pastures were infected by the saliva, urine, or manure of Southern
+cattle. There were not wanting keen observers who suggested that the
+disease was caused by ticks, but little weight was given to their view.
+
+Various workers had described bacteria which they had isolated from the
+organs of the diseased animals, but their findings could not be
+verified. In 1889, Smith and Kilbourne discovered a minute, pear-shaped
+organism (fig. 138) in the red blood corpuscles of a cow which had
+succumbed to Texas fever. On account of their shape they were given the
+generic name _Pyrososma_ and because they were usually found two in a
+corpuscle, the specific name, _bigeminum_. It is now generally accepted
+that the parasite is the same which Babes had observed the year before
+in Roumanian cattle suffering from hæmoglobinuria, and should be known
+as _Babesia bovis_ (Babes).
+
+[Illustration: 138. Babesia bovis in blood corpuscles. After Calli.]
+
+[Illustration: 139. The cattle tick (Boophilus annulatus). (_a_) Female;
+(_b_) male. After Comstock.]
+
+By a series of perfectly conclusive experiments carried on near
+Washington, D.C., Smith and Kilbourne showed that this organism was
+carried from Southern cattle to non-immune animals by the so-called
+Southern cattle tick, _Boophilus annulatus_ (= _Margaropus annulatus_)
+(fig. 139).
+
+Of fourteen head of native cattle placed in a field with tick-infested
+Northern cattle all but two contracted the disease. This experiment was
+repeated with similar results. Four head of native cattle kept in a plot
+with three North Carolina cattle which had been carefully freed from
+ticks remained healthy. A second experiment the same year gave similar
+results.
+
+Still more conclusive was the experiment showing that fields which had
+not been entered by Southern cattle but which had been infected by
+mature ticks taken from such animals would produce Texas fever in native
+cattle. On September 13, 1889, several thousand ticks collected from
+cattle in North Carolina three and four days before, were scattered in a
+small field near Washington. Three out of four native animals placed in
+this field contracted the disease. The fourth animal was not examined as
+to its blood but it showed no external symptoms of the disease.
+
+[Illustration: 140. Hyalomma ægypticum. After Nuttall and Warburton.]
+
+In these earlier experiments it was believed that the cattle tick acted
+as a carrier of the disease between the Southern cattle and the _soil_
+of the Northern pastures. "It was believed that the tick obtained the
+parasite from the blood of its host and in its dissolution on the
+pasture a certain resistant spore form was set free which produced the
+disease when taken in with the food." The feeding of one animal for some
+time with grass from the most abundantly infected field, without any
+appearance of the disease, made this hypothesis untenable.
+
+In the experimental work in 1890 the astonishing fact was brought out
+that the disease was conveyed neither by infected ticks disintegrating
+nor by their directly transferring the parasite, but that it was
+conveyed by the young hatched from eggs of infected ticks. In other
+words, the disease was hereditarily transferred to ticks of the second
+generation and they alone were capable of conveying it.
+
+Thus was explained the fact that Texas fever did not appear immediately
+along the route of Southern cattle being driven to Northern markets but
+that after a certain definite period it manifested itself. It was
+conveyed by the progeny of ticks which had dropped from the Southern
+cattle and deposited their eggs on the ground.
+
+These results have been fully confirmed by workers in different parts of
+the world,--notably by Koch, in Africa, and by Pound, in Australia.
+
+The disease is apparently transmitted by _Boophilus annulatus_ alone, in
+the United States, but it, or an almost identical disease, is conveyed
+by _Ixodes hexagonus_ in Norway, _Ixodes ricinus_ in Finland and France
+and by the three species, _Boophilus decoloratus_, _Hyalomma ægypticum_
+(fig. 140 and 141), and _Hæmaphysalis punctata_ in Africa.
+
+[Illustration: 141. Hyalomma ægypticum. Capitulum of female; (_a_)
+dorsal, (_b_) ventral aspect.]
+
+In spite of the detailed study which it has received, the life cycle of
+_Babesia bovis_ has not been satisfactorily worked out. The asexual
+reproduction in the blood of the vertebrate host has been described but
+the cycle in the tick is practically unknown.
+
+More successful attempts have been made to work out the life cycle of a
+related species, _Babesia canis_, which causes malignant jaundice in
+dogs in Africa and parts of Southern Europe. In this instance, also, the
+disease is transmitted by heredity to the ticks of the second
+generation. Yet the larval, or "seed ticks," from an infected female are
+not capable of conveying the disease, but only the nymphs and adults.
+Still more complicated is the condition in the case of _Babesia ovis_ of
+sheep, which Motas has shown can be conveyed solely by the adult,
+sexually mature ticks of the second generation.
+
+In _Babesia canis_, Christopher (1907) observed developmental stages in
+the tick. He found in the stomach of adult ticks, large motile
+club-shaped bodies which he considered as oökinetes. These bodies pass
+to the ovaries of the tick and enter the eggs where they become globular
+in form and probably represent an oocyst. This breaks up into a number
+of sporoblasts which enter the tissues of the developing tick and give
+rise to numerous sporozoites, which collect in the salivary glands and
+thence are transferred to the vertebrate host. A number of other species
+of _Babesia_ are known to infest vertebrates and in all the cases where
+the method has been worked out it has been found that the conveyal was
+by ticks. We shall not consider the cases more fully here, as we are
+concerned especially with the method of transfer of human diseases.
+
+
+TICKS AND ROCKY MOUNTAIN SPOTTED FEVER OF MAN--Ever since 1873 there has
+been known in Montana and Idaho a peculiar febrile disease of man, which
+has gained the name of "Rocky Mountain spotted fever." Its onset is
+marked by chills and fever which rapidly become acute. In about four to
+seven days there appears a characteristic eruption on the wrists, ankles
+or back, which quickly covers the body.
+
+McClintic (1912) states that the disease has now been reported from
+practically all of the Rocky Mountain States, including Arizona,
+California, Colorado, Idaho, Montana, Nevada, Oregon, Utah, Washington,
+and Wyoming. "Although the disease is far more prevalent in Montana and
+Idaho than in any of the other States, its spread has assumed such
+proportions in the last decade as to call for the gravest consideration
+on the part of both the state and national health authorities. In fact,
+the disease has so spread from state to state that it has undoubtedly
+become a very serious interstate problem demanding the institution of
+measures for its control and suppression."
+
+A peculiar feature of the Rocky Mountain spotted fever is a marked
+variation in its severity in different localities. In Montana, and
+especially in the famous Bitter Root Valley, from 33 per cent to 75 per
+cent of the cases result fatally. On the other hand, the fatality does
+not exceed four per cent in Idaho.
+
+In 1902, Wilson and Chowning reported the causative organism of spotted
+fever to be a blood parasite akin to the _Babesia_ of Texas fever, and
+made the suggestion that the disease was tick-borne. The careful studies
+of Stiles (1905) failed to confirm the supposed discovery of the
+organism, and the disease is now generally classed as due to an
+invisible virus. On the other hand, the accumulated evidence has fully
+substantiated the hypothesis that it is tick-borne.
+
+According to Ricketts (1907) the experimental evidence in support of
+this hypothesis was first afforded by Dr. L. P. McCalla and Dr. H. A.
+Brereton, in 1905. These investigators transmitted the disease from man
+to man in two experiments. "The tick was obtained 'from the chest of a
+man very ill with spotted fever' and 'applied to the arm of a man who
+had been in the hospital for two months and a half, and had lost both
+feet from gangrene due to freezing.' On the eighth day the patient
+became very ill and passed through a mild course of spotted fever,
+leaving a characteristic eruption. The experiment was repeated by
+placing the tick on a woman's leg and she likewise was infected with
+spotted fever."
+
+The most detailed studies were those of the late Dr. H. T. Ricketts, and
+it was he who clearly established the tick hypothesis. In the summer of
+1906 he found that guinea pigs and monkeys are very susceptible to
+spotted fever and can readily be infected by inoculation of blood from
+patients suffering from the disease. This opened the way to experimental
+work on tick transmission. A female tick was fed upon an infected guinea
+pig for two days, removed and isolated for two days and then placed upon
+a healthy guinea pig. After an incubation period of three and a half
+days the experimental animal contracted a well-marked case of the
+disease.
+
+A similar result was obtained at the same time by King, and later in the
+season Ricketts proved that the male tick was also capable of
+transmitting the disease. He found that there was a very intimate
+relation of the virus to the tick and that the transmission must be
+regarded as biological throughout. Ticks remained infective as long as
+they lived and would feed for a period of several months. If they
+acquired the disease in the larval or nymphal stage they retained it
+during molting and were infective in the subsequent stages. In a few
+cases the larvæ from an infected female were infective.
+
+The evidence indicated that the tick suffers from a relatively harmless,
+generalized infection and the virus proliferates in its body. The
+disease probably is transferred through the salivary secretion of the
+tick since inoculation experiments show that the salivary glands of the
+infected adult contain the virus.
+
+It is probable that in nature the reservoir of the virus of spotted
+fever is some one or more of the native small animals. Infected ticks
+have been found in nature, and as various wild animals are susceptible
+to the disease, it is obvious that it may exist among them unnoticed.
+Wilson and Chowning suggested that the ground squirrel plays the
+principal rôle.
+
+Unfortunately, much confusion exists regarding the correct name of the
+tick which normally conveys the disease. In the medical literature it is
+usually referred to as _Dermacentor occidentalis_, but students of the
+group now agree that it is specifically distinct. Banks has designated
+it as _Dermacentor venustus_ and this name is used in the publications
+of the Bureau of Entomology. On the other hand, Stiles maintains that
+the common tick of the Bitter Root Valley, and the form which has been
+collected by the authors who have worked on Rocky Mountain spotted fever
+in that region, is separable from _D. venustus_, and he has described it
+under the name of _Dermacentor andersoni_.
+
+Mayer (1911) has shown experimentally that spotted fever may be
+transmitted by several different species of ticks, notably _Dermacentor
+marginatus_, _Dermacentor variabilis_ and _Amblyomma americanum_. This
+being the case, the question of the exact systematic status of the
+species experimented upon in the Bitter Root Valley becomes less
+important, for since _Dermacentor occidentalis_, _Dermacentor venustus_
+and _Dermacentor andersoni_ all readily attack man, it is probable that
+either species would readily disseminate the disease if it should spread
+into their range.
+
+Hunter and Bishop (1911) have emphasized the fact that in the eastern
+and southern United States there occur several species which attack man,
+and any one of which might transmit the disease from animal to animal
+and from animal to man. The following species, they state, would
+probably be of principal importance in the Southern and Eastern States:
+the lone star tick (_Amblyomma americanum_); the American dog tick
+(_Dermacentor variabilis_); and the gulf-coast tick (_Amblyomma
+maculatum_). In the extreme southern portions of Texas, _Amblyomma
+cajennense_, is a common pest of man.
+
+Since the evidence all indicates that Rocky Mountain spotted fever is
+transmitted solely by the tick, and that some of the wild animals serve
+as reservoirs of the virus, it is obvious that personal prophylaxis
+consists in avoiding the ticks as fully as possible, and in quickly
+removing those which do attack. General measures along the line of tick
+eradication must be carried out if the disease is to be controlled. That
+such measures are feasible has been shown by the work which has been
+done in controlling the tick-borne Texas fever of cattle, and by such
+work as has already been done against the spotted fever tick, which
+occurs on both wild and domestic animals. Detailed consideration of
+these measures is to be found in the publications of the Public Health
+and Marine Hospital Service, and the Bureau of Entomology. Hunter and
+Bishopp give the following summarized recommendations for control or
+eradication measures in the Bitter Root Valley.
+
+(1) A campaign of education, whereby all the residents of the valley
+will be made thoroughly familiar with the feasibility of the plan of
+eradication, and with what it will mean in the development of the
+valley.
+
+(2) The obtaining of legislation to make it possible to dip or oil all
+live stock in the Bitter Root Valley.
+
+(3) The obtaining of an accurate census of the horses, cattle, sheep,
+mules, and dogs in the valley.
+
+(4) The construction of ten or more dipping vats.
+
+(5) The providing of materials to be used in the dipping mixture.
+
+(6) The organization of a corps of workers to carry on the operations.
+
+(7) The systematic dipping of the horses, cattle, sheep, and dogs of the
+valley on a definite weekly schedule from approximately March 10 to June
+9.
+
+(8) The treatment by hand of the animals in localities remote from vats,
+on the same schedule.
+
+They estimate that after three seasons' operations a very small annual
+expenditure would provide against reinfestation of the valley by the
+incoming of cattle from other places.
+
+Supplementary measures consist in the killing of wild mammals which may
+harbor the tick; systematic burning of the brush and debris on the
+mountain side; and in clearing, since the tick is seldom found on land
+under cultivation.
+
+
+
+
+CHAPTER X
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA [_Continued_]
+
+
+ARTHROPODS AND SPIROCHÆTOSES OF MAN AND ANIMALS
+
+The term spirochætoses is applied to diseases of man or animals which
+are due to protistan parasites belonging to the group of slender, spiral
+organisms known as spirochætes.
+
+There has been much discussion concerning the relationship Of the
+spirochætes. Formerly, they were regarded as bacteria closely related to
+the forms grouped in the genus _Spirillum_. The results of the detailed
+study which the spirochætes have received in recent years, have led most
+of the workers to consider them as belonging to the protozoa. The merits
+of the discussion we are not concerned with here, but rather with the
+fact that a number of diseases caused by spirochætes are
+arthropod-borne. The better known of these we shall discuss.
+
+
+AFRICAN RELAPSING FEVER OF MAN--It has long been known to the natives of
+Africa and to travelers in that country, that the bite of a certain
+tick, _Ornithodoros moubata_, may be followed by severe or even fatal
+fever of the relapsing type. Until recent years, it was supposed that
+the effect was due to some special virulence of the tick, just as nagana
+of cattle was attributed to the direct effect of the bite of the
+tsetse-fly. The disease is commonly known as "tick-fever" or by the
+various native names of the tick.
+
+In 1904, Ross and Milne, in Uganda, and Dutton and Todd on the Congo,
+discovered that the cause of the disease is a spirochæte which is
+transmitted by the tick. This organism has been designated by Novy and
+Knapp as _Spirochæta duttoni_.
+
+_Ornithodoros moubata_ (fig. 142), the carrier of African relapsing
+fever, or "tick-fever," is widely distributed in tropical Africa, and
+occurs in great numbers in the huts of natives, in the dust, cracks and
+crevices of the dirt floors, or the walls. It feeds voraciously on man
+as well as upon birds and mammals. Like others of the _Argasidæ_, it
+resembles the bed-bug in its habit of feeding primarily at night. Dutton
+and Todd observed that the larval stage is undergone in the egg and that
+the first free stage is that of the octopod nymph.
+
+[Illustration: 142. Ornithodoros moubata. (_a_) Anterior part of venter;
+(_b_) second stage nymph; (_c_) capitulum; (_d_) dorsal and (_e_)
+ventral aspect of female; (_f_) ventral aspect of nymph; (_g_) capitulum
+of nymph. After Nuttall and Warburton.]
+
+The evidence that the fever is transmitted by this tick is conclusive.
+Koch found that from five per cent to fifteen per cent, and in some
+places, fifty per cent of the ticks captured, harbored the spirochæte.
+The disease is readily transmitted to monkeys, rats, mice and other
+animals and the earlier experiments along these lines have been
+confirmed by many workers.
+
+Not only are the ticks which have fed on infected individuals capable of
+conveying the disease to healthy animals but they transmit the causative
+organism to their progeny. Thus Möllers (1907), working in Berlin,
+repeatedly infected monkeys through the bites of nymphs which had been
+bred in the laboratory from infected ticks. Still more astonishing was
+his discovery that ticks of the third generation were infective. In
+other words, if the progeny of infected ticks were fed throughout life
+on healthy animals, and on maturity deposited eggs, the nymphs which
+hatched from these eggs would still be capable of carrying the
+infection.
+
+The developmental cycle of the spirochæte within the tick has not been
+fully worked out, though the general conclusions of Leishman (1910) have
+been supported by the recent works of Balfour (1911 and 1912), and
+Hindle (1912), on the life cycle of spirochætes affecting fowls.
+
+_Spirochæta duttoni_ ingested by _Ornithodoros moubata_ apparently
+disappear within a few days, but Leishman believed that in reality they
+break up into minute granules which are to be found in the alimentary
+canal, the salivary glands and the Malpighian tubes of the tick. These
+granules, or "coccoid bodies," as Hindle calls them, are supposed to be
+the form in which the spirochætes infect the new host. We shall see
+later that Marchoux and Couvy (1913) dissent wholly from this
+interpretation.
+
+According to Leishman, and Hindle, the coccoid bodies are not injected
+into the vertebrate host with the saliva of the tick, as are the
+sporozoites of malaria with that of the mosquito. Instead, they pass out
+with the excrement and secondarily gain access to the wound inflicted by
+the tick.
+
+Nuttall (1912) calls attention to the fact that the geographical
+distribution of _Ornithodoros moubata_ is far wider than our present
+records show for the distribution of the relapsing fever in man and that
+there is every reason to fear the extension of the disease. Huts where
+the ticks occur should be avoided and it should be remembered that in
+infected localities there is special danger in sleeping on the ground.
+
+
+EUROPEAN RELAPSING FEVER--There is widely distributed in Europe a type
+of relapsing fever which is caused by _Spirochæta recurrentis_. It has
+long been supposed that this disease is spread by the bed-bug and there
+is some experimental evidence to show that it may be conveyed by these
+insects.
+
+In 1897, Tictin found that he could infect monkeys by inoculating the
+contents of bed-bugs which had fed upon a patient within forty-eight
+hours. Nuttall, in 1907, in one experiment succeeded in transmitting
+_Spirochæta recurrentis_ from mouse to mouse by bites of bed-bugs. The
+bugs, thirty-five in number, were transferred at short intervals from
+one mouse to another, not being allowed to take a full meal on the
+first, or infected mouse.
+
+On the other hand, there is much clinical evidence to show that the
+European relapsing fever like various other types of the disease is
+transmitted from man to man by head and body lice (_Pediculus humanus_
+and _Pediculus corporis_).
+
+Interesting supplementary evidence is that of Bayon's observations
+(1912), in Moscow. "Having visited the big municipal night hospitals at
+Moscow I soon noticed that they were kept with such scrupulous
+cleanliness, disinfected so lavishly, the beds of iron, the floor
+cemented, that it was not possible for bed-bugs to thrive to any extent
+on the premises. The people sleeping there were allowed, however, to
+sleep in their own clothes. The introduction of these model homes had
+not had any effect on the incidence of relapsing fever, for the places
+were still hot-beds of the fever during winter. On the other hand,
+though I changed my rooms several times, I found bugs in every
+successive lodging, and I was told in Moscow, this can hardly be
+avoided. Yet no foreigner, or Russian of the better class, ever catches
+relapsing fever. To this may be added the fact that when I asked for
+clothes-lice and promised to pay a kopec for two, the attendants from
+the night hostel brought me next morning a small ounce bottle crammed
+with _Pediculus capitis_ (= _P. humanus_), and _Pediculus vestimentorum_
+(= _P. corporis_) collected off the sleepers. If relapsing fever were
+transmitted by bed-bugs, it would be much more disseminated than it is
+at present in Moscow."
+
+Direct experimental evidence of the agency of lice in transmitting
+relapsing fever is especially clear in the case of a type of the disease
+prevalent in parts of North Africa. We shall consider this evidence
+later.
+
+
+OTHER TYPES OF RELAPSING FEVER OF MAN--In addition to the three types of
+human relapsing fever already referred to, several others have been
+distinguished and have been attributed to distinct species of
+spirochætes. The various spirochætoses of man are:
+
+African, caused by _S. duttoni_; European, caused by _S. recurrentis_;
+North African, caused by _S. berbera_; East African, caused by _S.
+rossi_; East Indian, caused by _S. carteri_; North American, caused by
+_S. novyi_; South American, caused by _S. duttoni_ (?).
+
+Nuttall (1912) in his valuable résumé of the subject, has emphasized
+that "in view of the morphological similarity of the supposedly
+different species of spirochætes and their individual variations in
+virulence, we may well doubt if any of the 'species' are valid. As I
+pointed out four years ago, the various specific names given to the
+spirochætes causing relapsing fever in man may be used merely for
+convenience _to distinguish strains or races_ of different origin. They
+cannot be regarded as valid names, in the sense of scientific
+nomenclature, for virulence and immunity reactions are not adequate
+tests of specificity."
+
+
+NORTH AFRICAN RELAPSING FEVER OF MAN--The type of human relapsing fever
+to be met with in Algeria, Tunis, and Tripoli, is due to a _Spirochæta_
+to which does not differ morphologically from _Spirochæta duttoni_, but
+which has been separated on biological grounds as _Spirochæta berberi_.
+
+Experimenting with this type of disease in Algeria, Sergent and Foly
+(1910), twice succeeded in transmitting it from man to monkeys by
+inoculation of crushed body lice and in two cases obtained infection of
+human subjects who had received infected lice under their clothing and
+who slept under coverings harboring many of the lice which had fed upon
+a patient. Their results were negative with _Argas persicus_, _Cimex
+lectularius_, _Musca domestica_, _Hæmatopinus spinulosus_ and
+_Ceratophyllus fasciatus_. They found body lice associated with every
+case of relapsing fever which they found in Algeria.
+
+Nicolle, Blaizot, and Conseil (1912) showed that the louse did not
+transmit the parasite by its bite. Two or three hours after it has fed
+on a patient, the spirochætes begin to break up and finally they
+disappear, so that after a day, repeated examinations fail to reveal
+them. They persist, nevertheless, in some unknown form, for if the
+observations are continued they reappear in eight to twelve days. These
+new forms are virulent, for a monkey was infected by inoculating a
+single crushed louse which had fed on infected blood fifteen days
+before.
+
+Natural infection is indirect. Those attacked by the insect scratch, and
+in this act they excoriate the skin, crush the lice and contaminate
+their fingers. The least abrasion of the skin serves for the entrance of
+the spirochætes. Even the contact of the soiled fingers on the various
+mucosa, such as the conjunctive of the eye, is sufficient.
+
+As in the case of _Spirochæta duttoni_, the organism is transmitted
+hereditarily in the arthropod vector. The progeny of lice which have fed
+on infected blood may themselves be infective.
+
+
+SPIROCHÆTOSIS OF FOWLS--One of the best known of the spirochætes
+transmitted by arthropods is _Spirochæta gallinarum_, the cause of a
+very fatal disease of domestic fowls in widely separated regions of the
+world. According to Nuttall, it occurs in Southeastern Europe, Asia,
+Africa, South America and Australia.
+
+In 1903, Marchoux and Salimbeni, working in Brazil, made the first
+detailed study of the disease, and showed that the causative organism is
+transmitted from fowl to fowl by the tick _Argas persicus_. They found
+that the ticks remained infective for at least five months. Specimens
+which had fed upon diseased birds in Brazil were sent to Nuttall and he
+promptly confirmed the experiments. Since that date many investigators,
+notably Balfour and Hindle, have contributed to the elucidating of the
+life-cycle of the parasite. Since it has been worked out more fully than
+has that of any of the human spirochætes, we present Hindle's diagram
+(fig. 143) and quote the brief summary from his preliminary paper
+(1911_b_).
+
+"Commencing with the ordinary parasite in the blood of the fowl, the
+spirochæte grows until it reaches a certain length (16-19µ) and then
+divides by transverse division. This process is repeated, and is
+probably the only method of multiplication of the parasite within the
+blood. When the spirochætes disappear from the circulation, some of them
+break up into the coccoid bodies which, however, do not usually develop
+in the fowl. When the spirochætes are ingested by _Argas persicus_, some
+of them pass through the gut wall into the cœlomic fluid. From this
+medium they bore their way into the cells of the various organs of the
+tick and there break up into a number of coccoid bodies. These
+intracellular forms multiply by ordinary fission in the cells of the
+Malpighian tubules and gonads. Some of the coccoid bodies are formed in
+the lumen of the gut and Malpighian tubules. The result is that some of
+the coccoid bodies may be present in the Malpighian secretion and
+excrement of an infected tick and when mixed with the coxal fluid may
+gain entry into another fowl by the open wound caused by the tick's
+bite. They then elongate and redevelop into ordinary spirochætes in the
+blood of the fowl, and the cycle may be repeated."
+
+[Illustration: 143. Spirochæta gallinarum. After Hindle.]
+
+Hindle's account is clear cut and circumstantial, and is quite in line
+with the work of Balfour, and of Leishman. Radically different is the
+interpretation of Marchoux and Couvy (1913). These investigators
+maintain that the granules localized in the Malpighian tubules in the
+larvæ and, in the adult, also in the ovules and the genital ducts of the
+male and female, are not derived from spirochætes but that they exist
+normally in many acariens. They interpret the supposed disassociation
+of the spirochæte into granules as simply the first phase, not of a
+process of multiplication, but of a degeneration ending in the death of
+the parasite. The fragmented chromatin has lost its affinity for stains,
+remaining always paler than that of the normal spirochætes. On the other
+hand, the granules of Leishman stain energetically with all the basic
+stains.
+
+Further, according to Marchoux and Couvy, infection takes place without
+the emission of the coxal fluid and indeed, soiling of the host by the
+coxal fluid diluting the excrement is exceptional. All of the organs of
+the Argasid are invaded by the parasites, but they pass from the
+cœlom into the acini of the salivary glands and collect in its
+efferent canal. The saliva serves as the vehicle of infection.
+
+Thus, the question of the life cycle of _Spirochæta gallinarum_, and of
+spirochætes in general, is an open one.
+
+It should be noted that _Argas persicus_, the carrier of _Spirochæta
+gallinarum_, is a common pest of poultry in the southwestern United
+States. Though the disease has not been reported from this country,
+conditions are such that if accidentally introduced, it might do great
+damage.
+
+
+OTHER SPIROCHÆTE DISEASES OF ANIMALS--About a score of other blood
+inhabiting spirochætes have been reported as occurring in mammals, but
+little is known concerning their life-histories. One of the most
+important is _Spirochæta theileri_ which produces a spirochætosis of
+cattle in the Transvaal. Theiler has determined that it is transmitted
+by an Ixodid tick, _Margaropus decoloratus_.
+
+
+TYPHUS FEVER AND PEDICULIDÆ
+
+Typhus is an acute, and continued fever, formerly epidemically prevalent
+in camps, hospitals, jails, and similar places where persons were
+crowded together under insanitary conditions. It is accompanied by a
+characteristic rash, which gives the disease the common name of
+"spotted" or "lenticular" fever. The causative organism is unknown.
+
+Typhus fever has not generally been supposed to occur in the United
+States, but there have been a few outbreaks and sporadic cases
+recognized. According to Anderson and Goldberger (1912_a_), it has been
+a subject of speculation among health authorities why, in spite of the
+arrival of occasional cases in this country and of many persons from
+endemic foci of the disease, typhus fever apparently does not gain a
+foothold in the United States. These same workers showed that the
+so-called Brill's disease, studied especially in New York City, is
+identical with the typhus fever of Mexico and of Europe.
+
+The conditions under which the disease occurs and under which it spreads
+most rapidly are such as to suggest that it is carried by some parasitic
+insect. On epidemiological grounds the insects most open to suspicion
+are the lice, bed-bugs and fleas.
+
+In 1909, Nicolle, Comte and Conseil, succeeded in transmitting typhus
+fever from infected to healthy monkeys by means of the body louse
+(_Pediculus corporis_). Independently of this work, Anderson and
+Goldberger had undertaken work along this line in Mexico, and in 1910
+reported two attempts to transmit the disease to monkeys by means of
+body lice. The first experiment resulted negatively, but the second
+resulted in a slight rise in temperature, and in view of later results
+it seems that this was due to infection with typhus.
+
+Shortly after, Ricketts and Wilder (1910) succeeded in transmitting the
+disease to the monkey by the bite of body lice in two experiments, the
+lice in one instance deriving their infection from a man and in another
+from the monkey. Another monkey was infected by typhus through the
+introduction of the feces and abdominal contents of infested lice into
+small incisions. Experiments with fleas and bed-bugs resulted
+negatively.
+
+Subsequently, Goldberger and Anderson (1912_b_) indicated that the head
+louse (_Pediculus humanus_) as well, may become infected with typhus. In
+an attempt to transmit typhus fever (Mexican virus) from man to monkey
+by subcutaneous injection of a saline suspension of crushed head lice,
+the monkeys developed a typical febrile reaction with subsequent
+resistance to an inoculation of virulent typhus (Mexican) blood. In one
+of the three experiments to transmit the disease from man to monkey by
+means of the bite of the head louse, the animal bitten by the presumably
+infected head lice proved resistant to two successive immunity tests
+with virulent typhus blood.
+
+In 1910, Ricketts and Wilder reported an experiment undertaken with a
+view to determining whether the young of infected lice were themselves
+infected. Young lice were reared to maturity on the bodies of typhus
+patients, so that if the eggs were susceptible to infection at any stage
+of their development, they would have every opportunity of being
+infected within the ovary. The eggs of these infected lice were
+obtained, they were incubated, and the young lice of the second
+generation were placed on a normal rhesus monkey. The experimenters were
+unable to keep the monkey under very close observation during the
+following three or four weeks, but from the fact that he proved
+resistant to a subsequent immunity test they concluded that he probably
+owed this immunity to infection by these lice of the second generation.
+
+Anderson and Goldberger (1912_b_) object that due consideration was not
+given to the possibility of a variable susceptibility of the monkey to
+typhus. Their similar experiment was "frankly negative."
+
+Prophylaxis against typhus fever is, therefore, primarily a question of
+vermin extermination. A brief article by Dr. Goldberger (1914) so
+clearly shows the practical application of his work and that of the
+other investigators of the subject, that we abstract from it the
+following account:
+
+"In general terms it may be stated that association with a case of
+typhus fever in the absence of the transmitting insect is no more
+dangerous than is association with a case of yellow fever in the absence
+of the yellow fever mosquito. Danger threatens only when the insect
+appears on the scene."
+
+"We may say, therefore, that to prevent infection of the individual it
+is necessary for him only to avoid being bitten by the louse. In theory
+this may readily be done, for we know that the body louse infests and
+attaches itself almost entirely to the body linen, and that boiling
+kills this insect and its eggs. Individual prophylaxis is based
+essentially, therefore, on the avoidance of contact with individuals
+likely to harbor lice. Practically, however, this is not always as easy
+as it may seem, especially under the conditions of such intimate
+association as is imposed by urban life. Particularly is this the case
+in places such as some of the large Mexican cities, where a large
+proportion of the population harbors this vermin. Under such
+circumstances it is well to avoid crowds or crowded places, such as
+public markets, crowded streets, or public assemblies at which the
+'peon' gathers."
+
+"Community prophylaxis efficiently and intelligently carried out is,
+from a certain point of view, probably easier and more effective in
+protecting the individual than is the individual's own effort to guard
+himself. Typhus emphasizes, perhaps better than any other disease, the
+fact that fundamentally, sanitation and health are economic problems. In
+proportion as the economic condition of the masses has improved--that
+is, in proportion as they could afford to keep clean--the notorious
+filth disease has decreased or disappeared. In localities where it still
+prevails, its further reduction or complete eradication waits on a
+further improvement in, or extension of, the improved economic status of
+those afflicted. Economic evolution is very slow process, and, while
+doing what we can to hasten it, we must take such precautions as
+existing conditions permit, looking to a reduction in or complete
+eradication of the disease."
+
+"When possible, public bath houses and public wash houses, where the
+poor may bathe and do their washings at a minimum or without cost,
+should be provided. Similar provision should be made in military and
+construction camps. Troops in the field should be given the opportunity
+as frequently as possible to wash and _scald_ or _boil_ their body
+linen."
+
+"Lodging houses, cheap boarding houses, night shelters, hospitals, jails
+and prisons, are important factors in the spread and frequently
+constitute foci of the disease. They should receive rigid sanitary
+supervision, including the enforcement of measures to free all inmates
+of such institutions of lice on admission."
+
+"So far as individual foci of the disease are concerned these should be
+dealt with by segregating and keeping under observation all exposed
+individuals for 14 days--the period of incubation--from the last
+exposure, by disinfecting (boiling or steaming) the suspected bedding,
+body linen, and clothes, for the destruction of any possible vermin that
+they may harbor, and by fumigating (with sulphur) the quarters that they
+may have occupied."
+
+"It will be noted that nothing has been said as to the disposition of
+the patient. So far as the patient is concerned, he should be removed to
+'clean' surroundings, making sure that he does not take with him any
+vermin. This may be done by bathing, treating the hair with an
+insecticide (coal oil, tincture of larkspur), and a complete change of
+body linen. Aside from this, the patient may be treated or cared for in
+a general hospital ward or in a private house, provided the sanitary
+officer is satisfied that the new surroundings to which the patient has
+been removed are 'clean,' that is, free from vermin. Indeed, it is
+reasonably safe to permit a 'clean' patient to remain in his own home if
+this is 'clean,' for, as has already been emphasized, there can be no
+spread in the absence of lice. This is a common experience in native
+families of the better class and of Europeans in Mexico City."
+
+"Similarly the sulphur fumigation above prescribed may be dispensed with
+as unnecessary in this class of cases."
+
+
+
+
+CHAPTER XI
+
+SOME POSSIBLE, BUT IMPERFECTLY ESTABLISHED CASES OF ARTHROPOD
+TRANSMISSION OF DISEASE
+
+
+INFANTILE PARALYSIS OR ACUTE ANTERIOR POLIOMYELITIS
+
+The disease usually known in this country as infantile paralysis or,
+more technically, as acute anterior poliomyelitis, is one which has
+aroused much attention in recent years.
+
+The causative organism of infantile paralysis is unknown, but it has
+been demonstrated that it belongs to the group of filterable viruses. It
+gives rise to a general infection, producing characteristic lesions in
+the central nervous system. The result of the injury to the motor nerves
+is a more or less complete paralysis of the corresponding muscle. This
+usually manifests itself in the legs and arms. The fatal cases are
+usually the result of paralysis of the muscles of respiration. Of the
+non-fatal cases about 60 per cent remain permanently crippled in varying
+degrees.
+
+Though long known, it was not until about 1890 that it was emphasized
+that the disease occurs in epidemic form. At this time Medin reported
+his observations on an epidemic of forty-three cases which occurred in
+and around Stockholm in 1887. Since then, according to Frost (1911),
+epidemics have been observed with increasing frequency in various parts
+of the world. The largest recorded epidemics have been those in Vermont,
+1894, 126 cases; Norway and Sweden, 1905, about 1,500 cases; New York
+City, 1907, about 2,500 cases. Since 1907 many epidemics have been
+reported in the United States, and especially in the Northern States
+east of the Dakotas. In 1912 there were over 300 cases of the disease in
+Buffalo, N. Y., with a mortality of somewhat over 11 per cent.
+
+In view of the sudden prominence and the alarming spread of infantile
+paralysis, there have been many attempts to determine the cause, and the
+manner in which the disease spreads and develops in epidemic form. In
+the course of these studies, the question of possible transmission by
+insects was naturally suggested.
+
+C. W. Howard and Clark (1912) presented the results of studies in this
+phase of the subject. They dealt especially with the house-fly, bedbug,
+head, and body lice, and mosquitoes. It was found that the house-fly
+(_Musca domestica_) can carry the virus of poliomyelitis in an active
+state for several days upon the surface of the body and for several
+hours within the gastro-intestinal tract. Mosquitoes and lice were found
+not to take up or maintain the virus. On the other hand, the bedbug
+(_Cimex lectularius_) was found to take the virus from the infected
+monkeys and to maintain it in a living state within the body for a
+period of seven days. This was demonstrated by grinding up in salt
+solution, insects which had fed on poliomyelitic animals and injecting
+the filtrate into a healthy monkey. The experimenters doubted that the
+bedbug is a carrier of the virus in nature.
+
+Earlier in the same year, Brues and Sheppard published the results of an
+intensive epidemiological study of the outbreak of 1911, in
+Massachusetts. Special attention had been paid to the possibility of
+insect transfer and the following conclusion was reached:
+
+"Field work during the past summer together with a consideration of the
+epidemiology of the disease so far as known, points strongly toward
+biting flies as possible carriers of the virus. It seems probable that
+the common stable-fly (_Stomoxys calcitrans_ L.) may be responsible to a
+certain extent for the spread of acute epidemic poliomyelitis, possibly
+aided by other biting flies, such as _Tabanus lineola_. No facts which
+disprove such a hypothesis have as yet been adduced, and experiments
+based upon it are now in progress."
+
+As stated by Brues (1913), especial suspicion fell upon the stable-fly
+because:
+
+1. The blood-sucking habits of the adult fly suit it for the transfer of
+virus present in the blood.
+
+2. The seasonal abundance of the fly is very closely correlated with the
+incidence of the disease, rising rapidly during the summer and reaching
+a maximum in July and August, then slowly declining in September and
+October.
+
+3. The geographical distribution of the fly is, so far as can be
+ascertained, wider, or at least co-extensive with that of poliomyelitis.
+
+4. _Stomoxys_ is distinctly more abundant under rural conditions, than
+in cities and thickly populated areas.
+
+5. While the disease spreads over districts quickly and in a rather
+erratic way, it often appears to follow along lines of travel, and it is
+known that _Stomoxys_ flies will often follow horses for long distances
+along highways.
+
+6. In a surprisingly large number of cases, it appeared probable that
+the children affected had been in the habit of frequenting places where
+_Stomoxys_ is particularly abundant, i.e., about stables, barnyards,
+etc.
+
+The experiments referred to were carried on during the summer of 1912
+and in September Dr. Rosenau announced that the disease was transferred
+by the bite of the stable-fly.
+
+A monkey infected by inoculation was exposed to the bites of upwards of
+a thousand of the _Stomoxys_ flies daily, by stretching it at full
+length and rolling it in a piece of chicken wire, and then placing it on
+the floor of the cage in which the flies were confined. The flies fed
+freely from the first, as well as later, after paralysis had set in.
+Alternating with the inoculated monkey, healthy monkeys were similarly
+introduced into the cage at intervals. New monkeys were inoculated to
+keep a supply of such infected animals and additional healthy ones were
+exposed to the flies, which fed willingly and in considerable numbers on
+each occasion. "Thus the flies were given every opportunity to obtain
+infection from the monkeys, since the animals were bitten during
+practically every stage of the disease from the time of the inoculation
+of the virus till their death following the appearance of paralysis. By
+the same arrangement the healthy monkeys were likely to be bitten by
+flies that had previously fed during the various stages of the disease
+on the infected monkeys. The flies had meanwhile enjoyed the opportunity
+of incubating the virus for periods varying from the day or two which
+usually elapses between consecutive feedings, to the two or three-week
+period for which at least some (although a very small percentage) of the
+flies lived in the cage."
+
+"In all, twelve apparently healthy monkeys of a small Japan species were
+exposed to the flies in the manner described for the infected monkeys.
+Some were placed in the cage only once or twice and others a number of
+times after varying intervals. These exposures usually lasted for about
+half an hour, but were sometimes more protracted. No results were
+apparent until two or three weeks after the experiment was well under
+way, and then in rather rapid succession six of the animals developed
+symptoms of poliomyelitis. In three, the disease appeared in a virulent
+form, resulting in death, while the other three experienced transient
+tremblings, diarrhœa, partial paralysis and recovery."--Brues, 1913.
+
+Very soon after the announcement of the results of experiments by
+Rosenau and Brues, they were apparently conclusively confirmed by
+Anderson and Frost (1912), who repeated the experiments, at Washington.
+They announced that through the bites of the _Stomoxys_ flies that had
+previously fed on infected monkeys, they had succeeded in experimentally
+infecting three healthy monkeys.
+
+The results of these experiments gained much publicity and in spite of
+the conservative manner in which they had been announced, it was widely
+proclaimed that infantile paralysis was conveyed in nature by the
+stable-fly and by it alone.
+
+Serious doubt was cast on this theory by the results of further
+experiments by Anderson and Frost, reported in May of 1913. Contrary to
+the expectations justified by their first experience, the results of all
+the later, and more extended, experiments were wholly negative. Not once
+were these investigators again able to transmit the infection of
+poliomyelitis through _Stomoxys_. They concluded that it was extremely
+doubtful that the insect was an important factor in the natural
+transmission of the disease, not only because of their series of
+negative results, "but also because recent experiments have afforded
+additional evidence of the direct transmissibility or contagiousness of
+poliomyelitis, and because epidemiological studies appear to us to
+indicate that the disease is more likely transmitted largely through
+passive human virus carriers."
+
+Soon after this, Kling and Levaditi (1913) published their detailed
+studies on acute anterior poliomyelitis. They considered that the
+experiments of Flexner and Clark (and Howard and Clark), who fed
+house-flies on emulsion of infected spinal cord, were under conditions
+so different from what could occur in nature that one could not draw
+precise conclusions from them regarding the epidemiology of the disease.
+They cited the experiments of Josefson (1912), as being under more
+reasonable conditions. He sought to determine whether the inoculation of
+monkeys with flies caught in the wards of the Hospital for Contagious
+Diseases at Stockholm, where they had been in contact with cases of
+poliomyelitis, would produce the disease. The results were completely
+negative.
+
+Kling and Lavaditi made four attempts of this kind. The flies were
+collected in places where poliomyelitics had dwelt, three, four and
+twenty-four after the beginning of the disease in the family and one,
+three, and fifteen days after the patient had left the house. These
+insects were for the greater part living and had certainly been in
+contact with the infected person. In addition, flies were used which had
+been caught in the wards of the Hospital for Contagious Diseases at
+Söderkoping, when numbers of poliomyelitics were confined there.
+Finally, to make the conditions as favorable as possible, the emulsions
+prepared from these flies were injected without previous filtering,
+since filtration often causes a weakening of the virus. In spite of
+these precautions, all their results were negative, none of the
+inoculated animals having contracted poliomyelitis. They also
+experimented with bedbugs which had fed upon infected patients at
+various stages of the disease, but the results in these cases also were
+wholly negative.
+
+Kling and Levaditi considered at length the possibility of transmission
+of the disease by _Stomoxys_. As a result of their epidemiological
+studies, they found that infantile paralysis continued to spread in
+epidemic form in the dead of winter, when these flies were very rare and
+torpid, or were even completely absent. Numerous cases developed in the
+northern part of Sweden late in October and November, long after snow
+had fallen. On account of the rarity of the Stomoxys flies during the
+period of their investigations they were unable to conduct satisfactory
+experiments. In one instance, during a severe epidemic, they found a
+number of the flies in a stable near a house inhabited by an infected
+family, though none was found in the house itself. These flies were used
+in preparing an emulsion which, after filtering, was injected into the
+peritoneal cavity of a monkey. The result was wholly negative.
+
+As for the earlier experiments, Kling and Levaditi believe if the flies
+were responsible for the transmission of the disease in the cases
+reported by Rosenau and Brues, and the first experiments of Anderson and
+Frost, it was because the virus of infantile paralysis is eliminated
+with the nasal secretions of paralyzed monkeys and the flies, becoming
+contaminated, had merely acted as accidental carriers.
+
+Still further evidence against the hypothesis of the transmission of
+acute anterior poliomyelitis by _Stomoxys calcitrans_ was brought
+forward by Sawyer and Herms (1913). Special precautions were used to
+prevent the transference of saliva or other possibly infectious material
+from the surface of one monkey to that of another, and to avoid the
+possibility of complicating the experiments by introducing other
+pathogenic organisms from wild flies, only laboratory-bred flies were
+used. In a series of seven carefully performed experiments, in which the
+conditions were varied, Sawyer and Herms were unable to transmit
+poliomyelitis from monkey to monkey through the agency of _Stomoxys_, or
+to obtain any indication that the fly is the usual agent for spreading
+the disease in nature.
+
+The evidence at hand to date indicates that acute anterior
+poliomyelitis, or infantile paralysis, is transmitted by contact with
+infected persons. Under certain conditions insects may be agents in
+spreading the disease, but their rôle is a subordinate one.
+
+
+Pellagra
+
+PELLAGRA is an endemic and epidemic disease characterized by a peculiar
+eruption or erythema of the skin (figs 144 and 145), digestive
+disturbances and nervous trouble. Insanity is a common result, rather
+than a precursor of the disease. The manifestations of pellagra are
+periodic and its duration indeterminate.
+
+[Illustration: 144. Pellagrous eruption on the face. After Watson.]
+
+The disease is one the very name of which was almost unknown in the
+United States until within the past decade. It has usually been regarded
+as tropical, though it occurs commonly in Italy and in various parts of
+Europe. Now it is known that it not only occurs quite generally in the
+United States but that it is spreading. Lavinder (1911) says that "There
+are certainly many thousand cases of the disease in this country, and
+the present situation must be looked upon with grave concern."
+
+It is not within the scope of this book to undertake a general
+discussion of pellagra. The subject is of such importance to every
+medical man that we cannot do better than refer to Lavinder's valuable
+précis. We can only touch briefly upon the entomological phases of the
+problems presented.
+
+The most commonly accepted theories regarding the etiology of the
+disease have attributed it to the use of Indian corn as an article of
+diet. This supposed relationship was explained either on the basis of,
+(a) insufficiency of nutriment and inappropriateness of corn as a prime
+article of food; (b) toxicity of corn or, (c) parasitism of certain
+organisms--fungi or bacteria--ingested with either sound or deteriorated
+corn.
+
+In 1905, Sambon proposed the theory of the protozoal origin of pellagra
+and in 1910 he marshalled an imposing array of objections to the theory
+that there existed any relationship between corn and the disease. He
+presented clear evidence that pellagra existed in Europe before the
+introduction of Indian corn from America, as an article of diet, and
+that its spread was not _pari passu_ with that of the use of corn. Cases
+were found in which the patients had apparently never used corn, though
+that is obviously difficult to establish. He showed that preventive
+measures based on the theory had been a failure. Finally, he believed
+that the recurrence of symptoms of the disease for successive springs,
+in patients who abstained absolutely from the use of corn, militated
+against the theory.
+
+[Illustration: 145. Pellagrous eruption on the hand. After Watson.]
+
+On the other hand, Sambon believed that the periodicity of the symptoms,
+peculiarities of distribution and seasonal incidence, and analogies of
+the symptoms to those of other parasitic diseases indicated that
+pellagra was of protozoal origin, and that it was insect-borne.
+
+The insect carriers, he believed to be one or more species of Simuliidæ,
+or black-flies. In support of this he stated that _Simulium_ appears to
+effect the same topographical conditions as pellagra, that in its imago
+stage it seems to present the same seasonal incidence, that it has a
+wide geographical distribution which seems to cover that of pellagra,
+and that species of the genus are known to cause severe epizootics.
+Concluding from his studies in Italy, that pellagra was limited almost
+wholly to agricultural laborers, he pointed out that the Simulium flies
+are found only in rural districts, and as a rule do not enter towns,
+villages, or houses.
+
+[Illustration: 146. A favorite breeding place of Simulium. Ithaca, N.
+Y.]
+
+When Sambon's detailed report was published in 1910, his theory was
+seized upon everywhere by workers who were anxious to test it and who,
+in most cases, were favorably disposed towards it because of the
+wonderful progress which had been made in the understanding of other
+insect-borne diseases. In this country, the entomological aspects of the
+subject have been dealt with especially by Forbes (1912), and by King
+and Jennings, under the direction of W. D. Hunter, of the Bureau of
+Entomology, and in coöperation with the Thompson-McFadden Pellagra
+Commission of the Department of Tropical Medicine of the New York
+Post-Graduate Medical School. An important series of experiments with
+monkeys has been undertaken by S. J. Hunter, of Kansas, but
+unfortunately we have as yet no satisfactory evidence that these animals
+are susceptible to the disease--a fact which renders the whole problem
+difficult.
+
+The accumulated evidence is increasingly opposed to Sambon's hypothesis
+of the transmission of pellagra by _Simulium_. This has been so clearly
+manifested in the work of the Thompson-McFadden Commission that we quote
+here from the report by Jennings (1914):
+
+"Our studies in 1912 convinced us that there was little evidence to
+support the incrimination of any species of _Simulium_ in South Carolina
+in the transmission of pellagra. Reviewing the group as a whole, we find
+that its species are essentially "wild" and lack those habits of
+intimate association with man which would be expected in the vector of
+such a disease as pellagra. Although these flies are excessively
+abundant in some parts of their range and are moderately so in
+Spartanburg County, man is merely an incidental host, and no disposition
+whatever to seek him out or to invade his domicile seems to be
+manifested. Critically considered, it is nearer the fact that usually
+man is attacked only when he invades their habitat."
+
+"As our knowledge of pellagra accumulates, it is more and more evident
+that its origin is in some way closely associated with the domicile. The
+possibility that an insect whose association with man and his immediate
+environment is, at the best, casual and desultory, can be active in the
+causation of the disease becomes increasingly remote."
+
+"Our knowledge of the biting habits of _Simulium_ is not complete, but
+it is evident, as regards American species at least, that these are
+sometimes not constant for the same species in different localities.
+Certain species will bite man freely when opportunity offers, while
+others have never been known to attack him. To assume that the proximity
+of a _Simulium_-breeding stream necessarily implies that persons in its
+vicinity must be attacked and bitten is highly fallacious. In
+Spartanburg County attacks by _Simulium_ seems to be confined to the
+immediate vicinity of the breeding-places. Our records and observations,
+exceedingly few in number, refer almost exclusively to such locations.
+Statements regarding such attacks, secured with much care and
+discrimination from a large number of persons, including many
+pellagrins, indicate conclusively that these insects are seldom a pest
+of man in this county. A certain number of the persons questioned were
+familiar with the gnats in other localities, but the majority were
+seemingly ignorant of the existence of such flies with biting habits.
+This is especially striking, in view of the fact that the average
+distance of streams from the homes of the pellagra cases studied was
+about 200 yards, many being at a distance of less than 200 yards, and
+that 78 per cent of these streams were found to be infested by larval
+_Simulium_. Such ignorance in a large number of persons cannot be
+overlooked and indicates strongly that our belief in the negligible
+character of local attacks by _Simulium_ is well founded."
+
+"In localities infested by 'sand-flies,' mosquitoes, etc., these pests
+are always well known and the ignorance described above is very
+significant."
+
+"Such positive reports as we received nearly always referred to bites
+received in the open, along streams, etc., and observations made of
+their attack were of those on field laborers in similar situations.
+Males engaged in agricultural pursuits are almost exempt from pellagra
+in Spartanburg County. During the season of 1913, in some two or three
+instances, observations were made of the biting of _Simulium_ and some
+additional and entirely creditable reports were received. These
+observations and reports were under conditions identical with those
+referred to in the reports of 1912 and confirm the conclusions based on
+the observations of that year. I would repeat with emphasis that it is
+inconceivable that a fly of the appearance and habits of the prevalent
+species of _Simulium_ could be present in such a region, especially
+about the haunts of man and attack him with sufficient frequency and
+regularity to satisfactorily account for so active and prevalent a
+disease as pellagra without being a well-known and recognized pest."
+
+"In connection with the conditions in the Piedmont region of South
+Carolina, it may be well to cite the results of a study of those in the
+arid region of western Texas."
+
+"In May, 1913, in company with Capt. J. F. Siler of the
+Thompson-McFadden Pellagra Commission, I visited the region of which
+Midland in Midland County is the center. This region is very dry and
+totally devoid of running water for a long distance in every direction.
+The only natural source of water-supply, a few water holes and ponds,
+were visited and found to be of such a nature that the survival of
+_Simulium_, far less its propagation in them, is absolutely impossible.
+The nearest stream affording possibilities as a source of _Simulium_ is
+60 miles away, while the average distance of such possibility is not
+less than 100 miles."
+
+"Artificial sources of water-supply were also investigated carefully and
+were found to offer no opportunity for the breeding of _Simulium_."
+
+"At Midland the histories of five cases of pellagra were obtained, which
+gave clear evidence that this place or its immediate vicinity was the
+point of origin. Persons of long residence in the country were
+questioned as to the occurrence of such flies as _Simulium_ and returned
+negative answers. These included a retired cattle owner, who is a man of
+education and a keen observer, an expert veterinarian stationed in the
+country who has the cattle of the country under constant observation,
+and a practical cattle man, manager of a ranch and of wide experience.
+The latter had had experience with 'Buffalo gnats' in other localities
+(in the East) and is well acquainted with them. His close personal
+supervision of the cattle under his charge, makes it practically certain
+that he would have discovered these gnats had they been present in the
+country."
+
+"At the time the study was made, _Simulium_ was breeding and active in
+the adult state in the vicinity of Dallas, Texas, in the eastern part of
+the state. We have here a region in which cases of pellagra have
+originated, yet in which _Simulium_ does not and cannot breed."
+
+Other possible insect vectors of pellagra have been studied in great
+detail and the available evidence indicates that if _any_ insect plays a
+rôle in the spread of the disease, _Stomoxys calcitrans_ most nearly
+fills the conditions. This conclusion was announced by Jennings and King
+in 1912, and has been supported by their subsequent work.
+
+Yet, after all the studies of the past decade, the old belief that
+pellagra is essentially of dietary origin is gaining ground. Goldberger,
+Waring and Willets (1914) of the United States Public Health Service
+summarize their conclusions in the statement, (1) that it is dependent
+on some yet undetermined fault in a diet in which the animal or
+leguminous protein component is disproportionately large and (2) that no
+pellagra develops in those who _consume_ a mixed, well-balanced, and
+varied diet, such, for example, as that furnished by the Government to
+the enlisted men of the Army, Navy, and Marine Corps.
+
+
+Leprosy
+
+LEPROSY is a specific, infectious disease due to _Bacillus lepræ_, and
+characterized by the formation of tubercular nodules, ulcerations, and
+disturbances of sensation. In spite of the long time that the disease
+has been known and the dread with which it is regarded, little is known
+concerning the method of transfer of the causative organism or the means
+by which it gains access to the human body.
+
+It is known that the bacilli are to be found in the tubercles, the scurf
+of the skin, nasal secretions, the sputum and, in fact in practically
+all the discharges of the leper. Under such conditions it is quite
+conceivable that they may be transferred in some instances from diseased
+to healthy individuals through the agency of insects and other
+arthropods. Many attempts have been made to demonstrate this method of
+spread of the disease, but with little success.
+
+Of the suggested insect carriers none seem to meet the conditions better
+than mosquitoes, and there are many suggestions in literature that these
+insects play an important rôle in the transmission of leprosy. The
+literature has been reviewed and important experimental evidence
+presented by Currie (1910). He found that mosquitoes feeding, under
+natural conditions, upon cases of nodular leprosy so rarely, if ever,
+imbibe the lepra bacillus that they cannot be regarded as one of the
+ordinary means of transference of this bacillus from lepers to the skin
+of healthy persons. He believes that the reason that mosquitoes that
+have fed on lepers do not contain the lepra bacillus is that when these
+insects feed they insert their proboscis directly into a blood vessel
+and thus obtain bacilli-free blood, unmixed with lymph.
+
+The same worker undertook to determine whether flies are able to
+transmit leprosy. He experimented with five species found in
+Honolulu,--_Musca domestica_, _Sarcophaga pallinervis_, _Sarcophaga
+barbata_, _Volucella obesa_ and an undetermined species of _Lucilia_.
+The experiments with _Musca domestica_ were the most detailed. From
+these experiments he concluded, first, that all of the above-named
+flies, when given an opportunity to feed upon leprous fluids, will
+contain the bacilli in their intestinal tracts and feces for several
+days after such feeding. Second, that considering the habits of these
+flies, and especially those of _Musca domestica_, it is certain that,
+given an exposed leprous ulcer, these insects will frequently convey
+immense numbers of lepra bacilli, directly or indirectly, to the skins,
+nasal mucosa, and digestive tracts of healthy persons. Additional
+evidence along this line has recently been brought forward by Honeij and
+Parker (1914), who incriminate both _Musca domestica_ and _Stomoxys
+calcitrans_. Whether or not such insect-borne bacilli are capable of
+infecting persons whose skin and mucosa are thus contaminated, Currie
+was unwilling to maintain, but he concludes that until we have more
+accurate knowledge on this point, we are justified in regarding these
+insects with grave suspicion of being one of the means of disseminating
+leprous infection.
+
+Various students of the subject have suggested that bed-bugs may be the
+carriers of leprosy and have determined the presence of acid-fast
+bacilli in the intestines of bed-bugs which had fed on leprous patients.
+Opposed to this, the careful experiments of Thompson (1913) and of
+Skelton and Parkham (1913) have been wholly negative.
+
+Borrel has recently suggested that _Demodex_, may play a rôle in
+spreading the infection in families. Many other insects and acariens
+have been suggested as possible vectors, but the experimental data are
+few and in no wise conclusive. The most that can be said is that it is
+quite possible that under favorable conditions the infection might be
+spread by any of the several blood-sucking forms or by house-flies.
+
+
+Verruga peruviana
+
+VERRUGA PERUVIANA is defined by Castellani and Chalmers as "a chronic,
+endemic, specific, general disorder of unknown origin, not contagious,
+but apparently inoculable, and characterized by an irregular fever
+associated with rheumatoid pains, anemia, followed by granulomatous
+swellings in the skin, mucous membranes, and organs of the body." It has
+been generally believed by medical men interested that the comparatively
+benign eruptive verruga is identical with the so-called Oroya, or
+Carrion's fever, a malignant type. This view is not supported by the
+work of Strong, Tyzzer and Brues, (1913).
+
+The disease is confined to South America and to definitely limited areas
+of those countries in which it does occur. It is especially prevalent in
+some parts of Peru.
+
+The causative organism and the method of transfer of verruga are
+unknown. Castellani and Chalmers pointed out in 1910 that the study of
+the distribution of the disease in Peru would impress one with the
+similarity to the distribution of the Rocky Mountain fever and would
+lead to the conclusion that the ætiological cause must in some way be
+associated with some blood-sucking animal, perhaps an arachnid, and that
+this is supported by the fact that the persons most prone to the
+infection are those who work in the fields.
+
+More recently, Townsend (1913), in a series of papers, has maintained
+that verruga and Carrion's disease are identical, and that they are
+transmitted to man by the bites of the Psychodid fly, _Phlebotomus
+verrucarum_. He succeeded in producing the eruptive type of the disease
+in experimental animals by injecting a physiological salt trituration of
+wild Phlebotomus flies. A cebus monkey was exposed from October so to
+November 6, by chaining him to a tree in the verruga zone, next to a
+stone wall from which the flies emerged in large numbers every night.
+Miliar eruption began to appear on the orbits November 13 and by
+November 21, there were a number of typical eruptions, with exudation on
+various parts of the body exactly like miliar eruptive sores commonly
+seen on legs of human cases.
+
+An assistant in the verruga work, George E. Nicholson, contracted the
+eruptive type of the disease, apparently as a result of being bitten by
+the Phlebotomus flies. He had slept in a verruga zone, under a tight
+net. During the night he evidently put his hands in contact with the
+net, for in the morning there were fifty-five unmistakable Phlebotomus
+bites on the backs of his hands and wrists.
+
+Townsend believes that in nature, lizards constitute the reservoir of
+the disease and that it is from them that the Phlebotomus flies receive
+the infection.
+
+
+Cancer
+
+There are not wanting suggestions that this dread disease is carried, or
+even caused, by arthropods. Borrel (1909) stated that he had found mites
+of the genus _Demodex_ in carcinoma of the face and of the mammæ. He
+believed that they acted as carriers of the virus.
+
+Saul (1910) and Dahl (1910) go much further, since they attribute the
+production of the malignant growth to the presence of mites which Saul
+had found in cancers. These Dahl described as belonging to a new
+species, which he designated _Tarsonemus hominis_. These findings have
+since been confirmed by several workers. Nevertheless, the presence of
+the mite is so rare that it cannot be regarded as an important factor in
+the causation of the disease. The theory that cancer is caused by an
+external parasite is given little credence by investigators in this
+field.
+
+
+IN CONCLUSION, it should be noted that the medical and entomological
+literature of the past few years abounds in suggestions, and in
+unsupported direct statements that various other diseases are
+insect-borne. Knab (1912) has well said "Since the discovery that
+certain blood-sucking insects are the secondary hosts of pathogenic
+parasites, nearly every insect that sucks blood, whether habitually or
+occasionally, has been suspected or considered a possible transmitter of
+disease. No thought seems to have been given to the conditions and the
+characteristics of the individual species of blood-sucking insects,
+which make disease transmission possible."
+
+He points out that "in order to be a potential transmitter of human
+blood-parasites, an insect must be closely associated with man and
+normally have opportunity to suck his blood repeatedly. It is not
+sufficient that occasional specimens bite man, as, for example, is the
+case with forest mosquitoes. Although a person may be bitten by a large
+number of such mosquitoes, the chances that any of these mosquitoes
+survive to develop the parasites in question, (assuming such development
+to be possible), and then find opportunity to bite and infect another
+person, are altogether too remote. Applying this criterion, not only the
+majority of mosquitoes but many other blood-sucking insects, such as
+Tabanidæ and Simuliidæ, may be confidently eliminated. Moreover, these
+insects are mostly in evidence only during a brief season, so that we
+have an additional difficulty of a very long interval during which there
+could be no propagation of the disease in question." He makes an
+exception of tick-borne diseases, where the parasites are directly
+transmitted from the tick host to its offspring and where, for this
+reason, the insect remains a potential transmitter for a very long
+period. He also cites the trypanosome diseases as possible exceptions,
+since the causative organisms apparently thrive in a number of different
+vertebrate hosts and may be transmitted from cattle, or wild animals, to
+man.
+
+Knab's article should serve a valuable end in checking irresponsible
+theorizing on the subject of insect transmission of disease.
+Nevertheless, the principles which he laid down cannot be applied to the
+cases of accidental carriage of bacterial diseases, or to those of
+direct inoculation of pyogenic organisms, or of blood parasites such as
+the bacillus of anthrax, or of bubonic plague. Accumulated evidence has
+justified the conclusion that certain trypanosomes pathogenic to man are
+harbored by wild mammals, and so form an exception. Townsend believes
+that lizards constitute the natural reservoir of verruga; and it seems
+probable that field mice harbor the organism of tsutsugamushi disease.
+Such instances are likely to accumulate as our knowledge of the relation
+of arthropods to disease broadens.
+
+
+
+
+CHAPTER XII
+
+HOMINOXIOUS ARTHROPODS
+
+
+The following synoptic tables are presented in the hope that they may be
+of service in giving the reader a perspective of the relationships of
+the Arthropoda in general and enabling him to identify the more
+important species which have been found noxious to man. Though
+applicable chiefly to the arthropods found in the United States, exotic
+genera and species which are concerned in the transmission of disease
+are also included. For this reason the keys to the genera of the Muscids
+of the world are given. As will be seen, the tables embrace a number of
+groups of species which are not injurious. This was found necessary in
+order that the student might not be lead to an erroneous determination
+which would result were he to attempt to identify a species which
+heretofore had not been considered noxious, by means of a key containing
+only the noxious forms. The names printed in BOLD FACED TYPE indicate
+the hominoxious arthropods which have been most commonly mentioned in
+literature.
+
+
+CRUSTACEA
+
+Arthropods having two pairs of antennæ which are sometimes modified for
+grasping, and usually with more than five pairs of legs. With but few
+exceptions they are aquatic creatures. Representatives are: Crabs,
+lobsters, shrimps, crayfish, water-fleas, and woodlice. To this class
+belongs the CYCLOPS (fig. 122) a genus of minute aquatic crustaceans of
+which at least one species harbors _Dracunculus medinensis_, the Guinea
+worm (fig. 121).
+
+
+MYRIAPODA
+
+Elongate, usually vermiform, wingless, terrestrial creatures having one
+pair of antennæ, legs attached to each of the many intermediate body
+segments. This group is divided into two sections, now usually given
+class rank: the DIPLOPODA or millipedes (fig. 13), commonly known as
+thousand legs, characterized by having two pairs of legs attached to
+each intermediate body segment, and the CHILOPODA or centipedes (fig.
+14) having only one pair of legs to each body segment.
+
+
+ARACHNIDA
+
+In this class the antennæ are apparently wanting, wings are never
+present, and the adults are usually provided with four pairs of legs.
+Scorpions, harvest-men, spiders, mites, etc.
+
+
+HEXAPODA (Insects)
+
+True insects have a single pair of antennæ, which is rarely vestigial,
+and usually one or two pairs of wings in the adult stage. Familiar
+examples are cockroaches, crickets, grasshoppers, bugs, dragon-flies,
+butterflies, moths, mosquitoes, flies, beetles, ants, bees and wasps.
+
+
+ORDERS OF THE ARACHNIDA
+
+a. Abdomen distinctly segmented. A group of orders including scorpions,
+    (fig. 11), whip-scorpions (fig. 10), pseudo-scorpions, solpugids
+    (fig. 12) harvest-men (daddy-long-legs or harvestmen), etc.
+    ARTHROGASTRA
+
+aa. Abdomen unsegmented, though sometimes with numerous annulations
+    SPHÆROGASTRA
+
+  b. A constriction between cephalothorax and abdomen (fig. 7). True
+      Spiders ARANEIDA
+
+  bb. No deep constriction between these parts.
+
+    c. Legs usually well developed, body more or less depressed (fig.
+        49). Mites ACARINA
+
+    cc. Legs stumpy or absent, body more or less elongate or vermiform,
+        or if shorter, the species is aquatic or semi-aquatic in habit.
+
+      d. Four pairs of short legs; species inhabiting moss or water.
+          Water-bears. TARDIGRADA
+
+      dd. Two pairs of clasping organs near the mouth, instead of legs,
+          in the adult; worm-like creatures parasitic within the nasal
+          passages, lungs, etc. of mammals and reptiles (fig. 148).
+          Tongue worms. LINGUATULINA
+
+[Illustration: 148. Linguatula. (_a_) larva; (enlarged). (_b_) adult;
+(natural size).]
+
+
+ACARINA[E]
+
+a. Abdomen annulate, elongate; very minute forms, often with but four
+    legs (fig. 62). DEMODICOIDEA
+
+  b. With but four legs of five segments each. Living on plants, often
+      forming galls. ERIOPHYIDÆ
+
+  bb. With eight legs, of three segments each. Living in the skin of
+      mammals. DEMODICIDÆ
+
+    To this family belongs the genus DEMODEX found in the sebaceous
+        glands and hair follicles of various mammals, including man. _D.
+        phylloides_ Csokor has been found in Canada on swine, causing
+        white tubercles on the skin. _D. bovis_ Stiles has been reported
+        from the United States on cattle, upon the skin of which they
+        form swellings. D. FOLLICULORUM Simon is the species found on
+        man. See page 78.
+
+aa. Abdomen not annulate nor prolonged behind; eight legs in the adult
+    stage.
+
+  b. With a distinct spiracle upon a stigmal plate on each side of the
+      body (usually ventral) above the third or fourth coxæ or a little
+      behind (fig. 50); palpi free; skin often coriaceous or leathery;
+      tarsi often with a sucker.
+
+    c. Hypostome large (fig. 50), furnished below with many recurved
+        teeth; venter with furrows, skin leathery; large forms, usually
+        parasitic. IXODOIDEA
+
+      d. Without scutum but covered by a more or less uniform leathery
+          integument; festoons absent; coxæ unarmed, tarsi without
+          ventral spurs; pulvilli absent or vestigial in the adults;
+          palpi cylindrical; sexual dimorphism slight. ARGASIDÆ
+
+        e. Body flattened, oval or rounded, with a distinct flattened
+            margin differing in structure from the general integument;
+            this margin gives the body a sharp edge which is not
+            entirely obliterated even when the tick is full fed.
+            Capitulum (in adults and nymphs) entirely invisible
+            dorsally, distant in the adult by about its own length from
+            the anterior border. Eyes absent. ARGUS Latr.
+
+          f. Body oblong; margin with quadrangular cells; anterior tibiæ
+              and metatarsi each about three times as long as broad. On
+              poultry, southwest United States. A. PERSICUS MINIATUS
+
+            _A. brevipes_ Banks, a species with proportionately shorter
+                legs has been recorded from Arizona.
+
+          ff. With another combination of characters. About six other
+              species of _Argas_ from various parts of the world,
+              parasitic on birds and mammals.
+
+        ee. Body flattened when unfed, but usually becoming very convex
+            on distention; anterior end more or less pointed and
+            hoodlike; margin thick and not clearly defined, similar in
+            structure to the rest of the integument and generally
+            disappearing on distention; capitulum subterminal, its
+            anterior portions often visible dorsally in the adult; eyes
+            present in some species.
+
+          f. Integument pitted, without rounded tubercles; body provided
+              with many short stiff bristles; eyes absent. On horses,
+              cattle and man (fig. 48). OTIOBIUS Banks.
+
+            O. MEGNINI, a widely distributed species, is the type of
+                this genus.
+
+          ff. Integument with rounded tubercles or granules; body
+              without stiff bristles. ORNITHODOROS Koch.
+
+            g. Two pairs of eyes; tarsi IV with a prominent subterminal
+                spur above; leg I strongly roughened. On cattle and man.
+                O. CORIACEUS
+
+            gg. No eyes; no such spur on the hind tarsi.
+
+              h. Tarsi I without humps above. _O. talaje._
+
+              hh. Tarsi I with humps above.
+
+                i. Tarsi IV without distinct humps above. On hogs,
+                    cattle and man. O. TURICATA
+
+                ii. Tarsi IV with humps nearly equidistant (fig. 142).
+                    Africa. O. MOUBATA
+
+[Illustration: 149. Hæmaphysalis wellingtoni. Note short palpi. After
+Nuttall and Warburton.]
+
+      dd. With scutum or shield (fig. 50); festoons usually present;
+          coxæ usually armed with spurs, tarsi generally with one or two
+          ventral spurs; pulvilli present in the adults; sexual
+          dimorphism pronounced. IXODIDÆ
+
+        e. With anal grooves surrounding anus in front; inornate;
+            without eyes; no posterior marginal festoons; venter of the
+            male with non-salient plates. Numerous species, 14 from the
+            United States, among them I. RICINUS (fig. 49 and 50),
+            SCAPULARIS, COOKEI, _hexagonus_, _bicornis_. IXODES Latr.
+            (including Ceratixodes).
+
+        ee. With anal groove contouring anus behind, or groove faint or
+            obsolete.
+
+          f. With short palpi (fig. 149).
+
+            g. Without eyes, inornate, with posterior marginal festoons;
+                male without ventral plates. Numerous species. _H.
+                chordeilis_ and _leporis-palustris_ from the United
+                States. _Hæmaphysalis_ Koch.
+
+[Illustration: 150. Stigmal plate of Dermacentor andersoni; (_a_) of
+male, (_b_) of female. After Stiles. (_c_) Dermacentor variabilis, male;
+(_d_) Glyciphagus obesus; (_e_) Otodectes cynotis; (_f_) Tyroglyphus
+lintneri; (_g_) Tarsonemus pallidus; (_h_) anal plate and mandible of
+Liponyssus; (_c_) to (_h_) after Banks.]
+
+            gg. With eyes.
+
+              h. Anal groove distinct; posterior marginal festoons
+                  present.
+
+                i. Base of the capitulum (fig. 150c) rectangular
+                    dorsally; usually ornate. DERMACENTOR Koch.
+
+                  j. Adults with four longitudinal rows of large
+                      denticles on each half of hypostome; stigmal plate
+                      nearly circular, without dorso-lateral
+                      prolongation, goblets very large, attaining 43µ to
+                      115µ in diameter; not over 40 per plate, each
+                      plate surrounded by an elevated row of regularly
+                      arranged supporting cells; white rust wanting;
+                      base of capitulum distinctly broader than long,
+                      its postero-lateral angles prolonged slightly, if
+                      at all; coxæ T with short spurs; trochanter I with
+                      small dorso-terminal blade. Texas, Arizona, etc.
+                      _D. nitens_
+
+[Illustration: 151. Rhipicephalus bursa, male. After Nuttall and
+Warburton.]
+
+                  jj. Adults with three longitudinal rows of large
+                      denticles on each half of hypostome; goblet cells
+                      always more than 40 per plate; whitish rust
+                      usually present.
+
+                    k. Dorso-lateral prolongation of stigmal plate small
+                        or absent; plates of the adults distinctly
+                        longer than broad; goblet cells large, usually
+                        30µ to 85µ in diameter, appearing as very coarse
+                        punctations on untreated specimens, but on
+                        specimens treated with caustic potash they
+                        appear very distinct in outline; base of
+                        capitulum distinctly (usually about twice)
+                        broader than long, the postero-lateral angles
+                        distinctly produced caudad; spurs of coxæ I
+                        long, lateral spur slightly longer than median;
+                        trochanter I with dorso-terminal spur. _D.
+                        albipictus_, (= _variegatus_), _salmoni_,
+                        _nigrolineatus_.
+
+                    kk. Dorso-lateral prolongation of stigmal plate
+                        distinct.
+
+                      l. Body of plate distinctly longer than broad;
+                          goblet cells of medium size, usually 17.5µ to
+                          35µ or 40µ in diameter, appearing as medium
+                          sized punctuations on untreated specimens, but
+                          on the specimens treated with caustic potash
+                          they appear very distinct in outline, which is
+                          not circular; base of capitulum usually less
+                          than twice as broad as long, the
+                          postero-lateral angles always distinctly
+                          prolonged caudad.
+
+                        m. Trochanter I with distinct dorso-subterminal
+                            retrograde sharp, digitate spur;
+                            postero-lateral angles of capitulum
+                            pronouncedly prolonged caudal, 112µ to 160µ
+                            long; goblet cells attain 13µ to 40µ in
+                            diameter; type locality California. D.
+                            OCCIDENTALIS
+
+                        mm. Trochanter I with dorso-terminal blade;
+                            postero-lateral angles of capitulum with
+                            rather short prolongations.
+
+                          n. Stigmal plate small, goblet cells not
+                              exceeding 45 in the male or 100 in the
+                              female; scutum with little rust, coxa I
+                              with short spurs, the inner distinctly
+                              shorter than the outer. _D.
+                              parumapertus-marginatus_
+
+                          nn. Stigmal plate larger; goblet cells over 70
+                              in the male and over 100 in the female;
+                              coxa I with longer spurs, inner slightly
+                              shorter than the outer; scutum with
+                              considerable rust. D. VENUSTUS[F]
+
+                      ll. Goblet cells small, rarely exceeding 17.6µ,
+                          occasionally reaching 19µ in diameter; on
+                          untreated specimens they appear as very fine
+                          granulations, and on specimens treated with
+                          caustic potash they may be difficult to see,
+                          but their large number can be determined from
+                          the prominent stems of the goblets; surface of
+                          outline of the goblets distinctly circular;
+                          base of the capitulum usually less than twice
+                          as broad as long, the postero-lateral angle
+                          distinctly prolonged caudad; spurs of coxæ I
+                          long. _D. reticulatus_ and _electus_ (=
+                          _variabilis_?)
+
+                ii. Base of the capitulum (fig. 151) usually hexagonal
+                    (except in the male of _puchellus_); and usually
+                    inornate.
+
+                  j. No ventral plate or shield in either sex (fig.
+                      153). R. BICORNIS from the United States.
+                      RHIPICENTOR Nuttall
+
+                  jj. Males with a pair of adanal shields, and usually a
+                      pair of accessory adanal shields. Numerous
+                      species, among them _R. sanguineus_ (fig. 154) and
+                      _texanus_, the latter from the United States.
+                      _Rhipicephalus_ Koch
+
+              hh. Anal grooves faint or obsolete; no marginal festoons.
+
+                i. Short palpi; highly chitinized; unfed adults of large
+                    size; coxæ conical; male with a median plate
+                    prolonged in two long spines projecting caudad;
+                    segments of leg pair IV greatly swollen (fig. 155,
+                    156). _M. winthemi_ _Margaropus_ Karsch
+
+[Illustration: 152. Monieziella (Histiogaster) emtomophaga-spermatica,
+ventral aspect, male and female. After Trouessart.]
+
+                ii. Very short palpi, ridged dorsally and laterally;
+                    slightly chitinized; unfed adults of smaller size;
+                    coxæ I bifid; male with adanal and accessory adanal
+                    shields (fig. 139). B. ANNULATUS. BOOPHILUS Curtis
+
+          ff. Palpi longer than broad (fig. 157).
+
+            g. Male with pair of adanal shields, and two posterior
+                abdominal protrusions capped by chitinized points;
+                festoons present or absent. Several species, among them
+                H. ÆGYPTICUM (fig. 140) from the old world. HYALOMMA
+                Koch
+
+            gg. Male without adanal shields but small ventral plaques
+                are occasionally present close to the festoons. Many
+                species, a few from the United States (fig. 157).
+                AMBLYOMMA Koch
+
+              h. Coxa I with but one spine; metatarsi (except I) with
+                  two thickened spurs at tips. _A. maculatum_
+
+              hh. Coxa I with two spines; metatarsi without stout spurs
+                  at tips, only slender hairs.
+
+                i. Projections of coxa I blunt and short. Large species
+                    on the gopher tortoise in Florida. _A. tuberculatum_
+
+                ii. Projections of coxa I longer, and at least one of
+                    them sharp pointed; second segment of palpus twice
+                    as long as the third; coxa IV of the male with a
+                    long spine.
+
+                  j. Porose areas nearly circular; shield of both sexes
+                      pale yellowish, with some silvery streaks and
+                      marks, and some reddish spots; shield of female as
+                      broad as long. A. CAJENNENSE (= MIXTUM).
+
+                  jj. Porose areas elongate, shield brown, in the female
+                      with an apical silvery mark, in the male with two
+                      small and two or four other silvery spots; shield
+                      of the female longer than broad (fig 158 e). A.
+                      AMERICANUM.
+
+[Illustration: 153. Rhipicentor bicornis, ventral aspect, male. After
+Nuttall and Warburton.]
+
+    cc. Hypostome small, without teeth, venter without furrows; body
+        often with coriaceous shields, posterior margin of the body
+        never crenulate (i.e. without festoons); no eyes. GAMASOIDEA.
+
+      d. Parasitic on vertebrates; mandibles fitted for piercing; body
+          sometimes constricted. DERMANYSSIDÆ.
+
+        e. Anal plate present. DERMANYSSINÆ.
+
+          f. Body short; legs stout, hind pair reaching much beyond the
+              tip of the body. On bats. _Pteroptus_ Dufour.
+
+          ff. Body long; hind legs not reaching beyond the tip of the
+              body.
+
+            g. Peritreme on the dorsum, very short; body distinctly
+                  constricted. _Ptilonyssus_ Berl.
+
+            gg. Peritreme on the venter, longer; body not distinctly
+                  constricted.
+
+                h. Mandibles in both sexes chelate. Parasitic on bats,
+                    mice and birds (fig. 150, h). LIPONYSSUS Kol.
+
+                  The species L. (= LEIOGNATHUS) SYLVIARUM frequents the
+                      nests of warblers. An instance is on record of
+                      these mites attacking man, causing a pruritis.
+
+                hh. Mandibles in the male chelate, in the female long,
+                    styliform (fig. 158 j). Parasitic on birds.
+                    DERMANYSSUS Dug. Two species of importance may be
+                    noted, _D. hirundinus_ and D. GALLINÆ. The latter
+                    (fig. 51) is a serious pest of poultry, sometimes
+                    attacking man, causing itching and soreness.
+
+        ee. Anal plate absent. In lungs and air passages of some
+            mammals. HALARACHNINÆ.
+
+      dd. Free or attached to insects, rarely on vertebrates.
+
+        e. First pair of legs inserted within the same body opening as
+            the oral tube; genital apertures surrounded by the sternum.
+            On insects. UROPODIDÆ.
+
+[Illustration: 154. Rhicephalus sanguineus, male. After Nuttall and
+Warburton.]
+
+        ee. First pair of legs inserted at one side of the mouth
+            opening; male genital aperture usually on the anterior
+            margin of the sternal plate. GAMASIDÆ.
+
+          This family contains a number of genera, some of which are
+              found upon mammals, though the majority affect only other
+              arthropods. One species, LÆLAPS STABULARIS, frequents the
+              bedding in stables, and in one instance at least, has
+              occasioned irritation and itching, in man.
+
+  bb. No distinct spiracle in the stigmal plate on each side of the
+      body.
+
+    c. Body usually coriaceous, with few hairs, with a specialized seta
+        arising from a pore near each posterior corner of the
+        cephalothorax; no eyes; mouth parts and palpi very small;
+        ventral openings of the abdomen large; tarsi without sucker. Not
+        parasitic. ORIBATOIDEA.
+
+    cc. Body softer; without such specialized seta.
+
+      d. Aquatic species. HYDRACHNOIDEA.
+
+      dd. Not aquatic.
+
+        e. Palpi small, three segmented, adhering for some distance to
+            the lip; ventral suckers at genital opening or near anal
+            opening usually present; no eyes; tarsi often end in
+            suckers; beneath the skin on the venter are seen rod-like
+            epimera that support the legs; body often entire. Adults
+            frequently parasitic. SARCOPTOIDEA.
+
+          f. With tracheæ; no ventral suckers; legs ending in claws;
+              body divided into cephalothorax and abdomen; the female
+              with a clavate hair between legs I and II. Usually not
+              parasitic on birds and mammals. TARSONEMIDÆ
+
+            g. Hind legs of female ending in claw and sucker as in the
+                other pairs. PEDICULOIDINÆ
+
+              To this sub-family belongs the genus PEDICULOIDES
+
+              P. ventricosus is described on page 69.
+
+[Illustration: 155. Margaropus winthemi, male. After Nuttall and
+Warburton.]
+
+[Illustration: 156. Margaropus winthemi, capitulum and scutum.
+After Nuttall and Warburton.]
+
+            gg. Hind legs of the female end in long hairs. TARSONEMINÆ
+
+              TARSONEMUS INTECTUS Karpelles, normally found upon grain,
+                  is said to attack man in Hungary and Russia. Other
+                  species of the genus affect various plants (c.f. fig.
+                  150, g).
+
+          ff. Without tracheæ; no such clavate hair.
+
+            g. Genital suckers usually present; integument usually
+                without fine parallel lines.
+
+              h. Legs short, without clavate hair on tarsi I and II. On
+                  insects. CANESTRINIDÆ.
+
+              hh. Legs longer, with a clavate hair on tarsi I and II.
+                  Not normally parasitic except on bees. TYROGLYPHIDÆ
+
+                i. Dorsal integument more or less granulate; claws very
+                    weak, almost invisible; some hairs of the body
+                    plainly feathered; ventral apertures large.
+                    GLYCIPHAGUS Her.
+
+                  This genus occurs in the United States. In Europe the
+                      mites have been found feeding on all sorts of
+                      substances. They are known as sugar mites and
+                      cause the disease known as grocer's itch. G.
+                      DOMESTICUS and G. PRUNORUM are old world species
+                      (fig. 150, d).
+
+                ii. Dorsal integument not granulate; claws distinct; no
+                    prominent feathered hairs; ventral aperture small.
+
+                  j. Mandibles not chelate; elongate, and toothed below;
+                      body without long hairs; palpi enlarged at tip and
+                      provided with two divergent bristles. Species feed
+                      on decaying substances. _Histiostoma_ Kram.
+
+                  jj. Mandibles chelate; palpi not enlarged at the tip,
+                      nor with two bristles.
+
+                    k. No clavate hair on the base of tarsi I and II; no
+                        suture between cephalothorax and abdomen. Live
+                        on bees or in their nests. _Trichotarsus_ Can.
+
+                    kk. A clavate or thickened hair at the base of tarsi
+                        I and II.
+
+                      l. The bristle on the penultimate segment of the
+                          legs arises from near the middle; no suture
+                          between the cephalothorax and abdomen. The
+                          species, some of which occur in the United
+                          States, feed on dried fruit, etc.
+                          _Carpoglyphus_ Robin.
+
+                      ll. The bristle on the penultimate segment of the
+                          legs arise from near the tip; a suture between
+                          cephalothorax and abdomen.
+
+                        m. Cephalothorax with four distinct and long
+                            bristles in a transverse row; tarsi I and II
+                            about twice as long as the preceding segment
+                            (fig. 150 f). TYROGLYPHUS Latr.
+
+                          n. Some bristles on tarsi I and II near
+                              middle, distinctly spine-like; the sense
+                              hair about its length from the base of the
+                              segment. Several species in the United
+                              States belong to this group.
+
+                          nn. No spine-like bristles near the middle of
+                              the tarsi; sense hair not its length from
+                              the base of the segment.
+
+                            o. Of the terminal abdominal bristles, only
+                                two are about as long as the abdomen;
+                                leg I of the male greatly thickened and
+                                with a spine at apex of the femur below.
+                                T. FARINÆ.
+
+                            oo. Of the terminal abdominal bristles at
+                                least six or more are very long, nearly
+                                as long as the body.
+
+                              p. Bristles of the body distinctly plumose
+                                  or pectinate; tarsi very long. T.
+                                  LONGIOR.
+
+                              pp. Bristles of the body not pectinate.
+
+                                q. In mills, stored foods, grains, etc.
+                                    Third and fourth joints of hind legs
+                                    scarcely twice as long as broad;
+                                    abdominal bristles not unusually
+                                    long; legs I and II of the male not
+                                    unusually stout. T. AMERICANUS.
+
+                                qq. With other characters and habits.
+                                    _T. lintneri_ (fig. 150 f) the
+                                    mushroom mite, and several other
+                                    species.
+
+                        mm. Cephalothorax with but two long distinct
+                            bristles (besides the frontal pair), but
+                            sometimes a very minute intermediate pair;
+                            tarsi I and II unusually short and not twice
+                            as long as the preceding segment.
+
+                          n. Tarsi with some stout spines. RHIZOGLYPHUS
+                              Clap.
+
+                            The species of this genus are vegetable
+                                feeders. Several occur in the United
+                                States. R. PARASITICUS and R.
+                                SPINITARSUS have been recorded from the
+                                old world, attacking human beings who
+                                handle affected plants.
+
+                          nn. Tarsi with only fine hairs. MONIEZIELLA
+                              Berl.
+
+                            The species of this genus, as far as known,
+                                are predaceous or feed on recently
+                                killed animal matter. Several species
+                                occur in the United States. M. (=
+                                HISTIOGASTER) ENTOMOPHAGA (fig. 152)
+                                from the old world has been recorded as
+                                injurious to man.
+
+            gg. Genital suckers absent; integument with fine parallel
+                lines. Parasitic on birds and mammals.
+
+              h. Possessing a specially developed apparatus for clinging
+                  to hairs of mammals. LISTROPHORIDÆ.
+
+              hh. Without such apparatus.
+
+                i. Living on the plumage of birds. ANALGESIDÆ.
+
+                ii. In the living tissues of birds and mammals.
+
+                  j. Vulva longitudinal. In the skin and cellular
+                      tissues of birds. CYTOLEICHIDÆ.
+
+                    This family contains two species, both occurring in
+                        the United States on the common fowl.
+                        _Laminosioptes cysticola_ occurs on the skin and
+                        also bores into the subcutaneous tissue where it
+                        gives rise to a calcareous cyst. _Cytoleichus
+                        nudus_ is most commonly found in the air
+                        passages and air cells.
+
+                  jj. Vulva transverse. In the skin of mammals and
+                      birds. SARCOPTIDÆ
+
+                    k. Anal opening on the dorsum.
+
+                      l. Third pair of legs in the male without apical
+                          suckers. On cats and rabbits. NOTÅ’DRES
+                          Rail.
+
+                        The itch mite of the cat, N. CATI (fig. 61) has
+                            been recorded on man.
+
+                      ll. Third leg in the male with suckers. On bats
+                          _Prosopodectes_ Can.
+
+                    kk. Anal opening below.
+
+                      l. Pedicel of the suckers jointed; mandibles
+                          styliform and serrate near the tip. PSOROPTES
+                          Gerv. P. COMMUNIS OVIS is the cause of sheep
+                          scab.
+
+                      ll. Pedicel of the suckers not jointed; mandibles
+                          chelate.
+
+                        m. No suckers on the legs of the females;
+                            parasitic on birds, including chickens. _C.
+                            mutans_ is itch mite of chickens.
+                            _Cnemidocoptes_ Fürst.
+
+                        mm. Suckers at least on legs I and II; parasitic
+                            on mammals.
+
+                          n. Legs very short; in the male the hind pairs
+                              equal in size; body usually short.
+                              SARCOPTES Latr.
+
+                            S. SCABIEI is the itch mite of man (fig.
+                                56).
+
+[Illustration: 157. Amblyomma, female. After Nuttall and Warburton.]
+
+                          nn. Legs more slender; in the male the third
+                              pair is much larger than the fourth; body
+                              more elongate.
+
+                            o. Female with suckers on the fourth pair of
+                                legs. Species do not burrow in the skin,
+                                but produce a scab similar to sheep
+                                scab. They occur in the ox, horse, sheep
+                                and goat. CHORIOPTES Gerv. C. SYMBIOTES
+                                BOVIS of the ox has been recorded a few
+                                times on man.
+
+                            oo. Female without suckers to the fourth
+                                legs.
+
+                              p. Hind part of the male abdomen with two
+                                  lobes. On a few wild animals.
+                                  _Caparinia_ Can.
+
+                              pp. Hind part of the male abdomen without
+                                  lobes. Live in ears of dogs and cats.
+                                  _Otodectes_ Canestr.
+
+                                _O. cynotis_ Hering (fig. 150 e) has
+                                    been taken in the United States.
+
+        ee. Palpi usually of four or five segments, free; rarely with
+            ventral suckers near genital or anal openings; eyes often
+            present; tarsi never end in suckers; body usually divided
+            into cephalothorax and abdomen; rod-like epimera rarely
+            visible; adults rarely parasitic.
+
+          f. Last segment of the palpi never forms a thumb to the
+              preceding segment; palpi simple, or rarely formed to hold
+              prey; body with but few hairs. EUPODOIDEA.
+
+            g. Palpi often geniculate, or else fitted for grasping prey;
+                mandibles large and snout like; cephalothorax with four
+                long bristles above, two in front, two behind; last
+                segment of leg I longer than the preceding segment,
+                often twice as long. BDELLIDÆ.
+
+            gg. Palpi never geniculate (fig. 158a), nor fitted for
+                grasping prey: beak small; cephalothorax with bristles
+                in different arrangement; last segment of leg I shorter
+                or but little longer than the preceding joint; eyes when
+                present near posterior border. EUPODIDÆ
+
+              Moniez has described a species from Belgium (TYDEUS
+                  MOLESTUS) which attacks man. It is rose colored;
+                  eyeless; its legs are scarcely as long as its body,
+                  the hind femur is not thickened; the mandibles are
+                  small and the anal opening is on the venter. The
+                  female attains a length of about 0.3 mm.
+
+          ff. Last segment of the palpus forms a thumb to the preceding,
+              which ends in a claw (with few exceptions); body often
+              with many hairs (fig. 158 k). TROMBIDOIDEA.
+
+            g. Legs I and II with processes bearing spines; skin with
+                several shields; coxæ contiguous. CÆCULIDÆ.
+
+            gg. Legs I and II without such processes; few if any
+                shields.
+
+              h. Palpi much thickened on the base, moving laterally,
+                  last joint often with two pectinate bristles; no eyes;
+                  legs I ending in several long hairs; adult sometimes
+                  parasitic. CHEYLETIDÆ
+
+                CHEYLETUS ERUDITUS, which frequents old books, has once
+                    been found in pus discharged from the ear of man.
+
+              hh. Palpi less thickened, moving vertically; eyes usually
+                  present; leg I not ending in long hairs.
+
+                i. Coxæ contiguous, radiate; legs slender, bristly; body
+                    with few hairs; no dorsal groove; tarsi not swollen.
+                    ERYTHRÆIDÆ.
+
+                ii. Coxæ more or less in two groups; legs less bristly.
+
+[Illustration: 158. (_a_) Tydeus, beak and leg from below; (_b_)
+Cheyletus pyriformis, beak and palpus; (_c_) beak and claw of
+Pediculoides; (_d_) leg of Sarcoptes; (_e_) scutum of female of
+Amblyomma americana; (_f_) leg I and tip of mandible of Histiostoma
+americana; (_g_) Histiogaster malus, mandible and venter; (_h_)
+Aleurobius farinæ, palpus and leg I of male; (_i_) Otodectes cynotis, tip
+of abdomen of male, (_j_) beak and anal plate of Dermanyssus gallinæ;
+(_k_) palpus of Allothrombium. (_a_) to (_j_) after Banks.]
+
+                  j. Body with fewer, longer hairs; often spinning
+                      threads; no dorsal groove; tarsi never swollen;
+                      mandibles styliform (for piercing). TETRANYCHIDÆ
+
+                    The genus TETRANYCHUS may be distinguished from the
+                        other genera occurring in the United States by
+                        the following characters: No scale-like
+                        projections on the front of the cephalothorax;
+                        legs I as long or longer than the body; palp
+                        ends in a distinct thumb; the body is about 1.5
+                        times as long as broad. T. MOLESTISSIMUS Weyenb.
+                        from South America, and T. TELARIUS from Europe
+                        and America ordinarily infesting plants, are
+                        said also to molest man.
+
+                  jj. Body with many fine hairs or short spines; not
+                      spinning threads; often with dorsal groove; tarsi
+                      often swollen.
+
+                    k. Mandibles styliform for piercing. RHYCHOLOPHIDÆ.
+
+                    kk. Mandibles chelate, for biting. TROMBIDIDÆ
+
+                      The genus TROMBIDIUM has recently been subdivided
+                          by Berlese into a number of smaller ones, of
+                          which some five or six occur in the United
+                          States. The mature mite is not parasitic but
+                          the larvæ which are very numerous in certain
+                          localities will cause intense itching,
+                          soreness, and even more serious complications.
+                          They burrow beneath the skin and produce
+                          inflamed spots. They have received the
+                          popular name of "RED BUG." The names LEPTUS
+                          AMERICANUS and L. IRRITANS have been applied
+                          to them, although they are now known to be
+                          immature stages. (Fig. 44.)
+
+
+HEXAPODA (Insecta)
+
+The Thysanura (springtails and bristletails), the Neuropteroids
+(may-flies, stone-flies, dragon-flies, caddis-flies, etc.), Mallophaga
+(bird lice), Physopoda (thrips), Orthoptera (grasshoppers, crickets,
+roaches), are of no special interest from our viewpoint. The remaining
+orders are briefly characterized below.
+
+
+SIPHUNCULATA (page 275)
+
+Mouth parts suctorial; beak fleshy, not jointed; insect wingless;
+parasitic upon mammals. Metamorphosis incomplete. Lice.
+
+
+HEMIPTERA (page 275)
+
+Mouth parts suctorial; beak or the sheath of the beak jointed; in the
+mature state usually with four wings. In external appearance the
+immature insect resembles the adult except that the immature form (i.e.
+nymph) never has wings, the successive instars during the process of
+growth, therefore, are quite similar; and the metamorphosis is thus
+incomplete. To this order belong the true bugs, the plant lice, leaf
+hoppers, frog hoppers, cicadas, etc.
+
+
+LEPIDOPTERA
+
+The adult insect has the body covered with scales and (with the rare
+exception of the females of a few species) with four wings also covered
+with scales. Proboscis, when present, coiled, not segmented, adapted for
+sucking. Metamorphosis complete, i.e. the young which hatches from the
+egg is quite unlike the adult, and after undergoing several molts
+transforms into a quiescent pupa which is frequently enclosed in a
+cocoon from which the adult later emerges. The larvæ are known as
+caterpillars. Butterflies and moths.
+
+
+DIPTERA (page 285)
+
+The adult insect is provided with two, usually transparent, wings, the
+second pair of wings of other insects being replaced by a pair of
+halteres or balancers. In a few rare species the wings, or halteres, or
+both, are wanting. The mouth parts, which are not segmented, are adapted
+for sucking. The tarsi are five-segmented. Metamorphosis complete. The
+larvæ, which are never provided with jointed legs, are variously known
+as maggots, or grubs, or wrigglers. Flies, midges, mosquitoes.
+
+
+SIPHONAPTERA (page 316)
+
+Mouth parts adapted for sucking; body naked or with bristles and spines;
+prothorax well developed; body compressed; tarsi with five segments;
+wings absent. Metamorphosis complete. The larva is a wormlike creature.
+Fleas.
+
+
+COLEOPTERA
+
+Adult with four wings (rarely wanting), the first pair horny or
+leathery, veinless, forming wing covers which meet in a line along the
+middle of the back. Mouth parts of both immature stages and adults
+adapted for biting and chewing. Metamorphosis complete. The larvæ of
+many species are known as grubs. Beetles.
+
+
+HYMENOPTERA
+
+Adult insect with four, usually transparent, wings, wanting in some
+species. Mouth parts adapted for biting and sucking; palpi small; tarsi
+four or five-segmented. Metamorphosis complete. Parasitic four-winged
+flies, ants, bees, and wasps.
+
+
+SIPHUNCULATA AND HEMIPTERA
+
+a. Legs with claws fitted for clinging to hairs; wings wanting;
+    spiracles of the abdomen on the dorsal surface. (= ANOPLURA =
+    PARASITICA) SIPHUNCULATA.
+
+  b. Legs not modified into clinging hooks; tibia and tarsus very long
+      and slender; tibia without thumb-like process; antennæ
+      five-segmented HÆMATOMYZIDÆ Endr.
+
+    _Hæmatomyzus elephantis_ on the elephant.
+
+  bb. Legs modified into clinging hooks; tibia and tarsus usually short
+      and stout; tibia with a thumb-like process; head not anteriorly
+      prolonged, tube-like.
+
+    c. Body depressed; a pair of stigmata on the mesothorax, and
+        abdominal segments three to eight; antennæ three to
+        five-segmented.
+
+      d. Eyes large, projecting, distinctly pigmented; pharynx short and
+          broad; fulturæ (inner skeleton of head) very strong and broad,
+          with broad arms; proboscis short, scarcely attaining the
+          thorax. PEDICULIDÆ
+
+        e. Antennæ three-segmented. A few species occurring upon old
+            world monkeys. _Pedicinis_ Gerv.
+
+        ee. Antennæ five-segmented.
+
+          f. All legs stout; thumb-like process of the tibia very long
+              and slender, beset with strong spines, fore legs stouter
+              than the others; abdomen elongate, segments without
+              lateral processes; the divided telson with a conical
+              process posteriorly upon the ventral side. PEDICULUS L.
+
+            g. Upon man.
+
+              h. Each abdominal segment dorsally with from one to three
+                  more or less regular transverse rows of small setæ;
+                  antenna about as long as the width of the head. Head
+                  louse (fig. 65). P. HUMANUS.
+
+              hh. "No transverse rows of abdominal setæ; antenna longer
+                  than the width of the head; species larger." Piaget.
+                  Body louse of man. P. CORPORIS.
+
+            gg. Upon apes and other mammals. _P. pusitatus_ (?).
+
+          ff. Fore legs delicate, with very long and slender claws;
+              other legs very stout with short and stout claws;
+              thumb-like process of the tibia short and stout; abdomen
+              very short and broad; segment one to five closely crowded,
+              thus the stigmata of segments three to five apparently
+              lying in one segment; segments five to eight with lateral
+              processes; telson without lateral conical appendages (fig.
+              69). Crab louse of man. PHTHIRUS PUBIS.
+
+      dd. Eyes indistinct or wanting; pharynx long and slender, fulturæ
+          very slender and closely applied to the pharynx; proboscis
+          very long. Several genera found upon various mammals.
+          HÆMATOPINIDÆ.
+
+    cc. Body swollen; meso- and metathorax, and abdominal segments two
+        to eight each with a pair of stigmata; eyes wanting; antennæ
+        four or five-segmented; body covered with stout spines. Three
+        genera found upon marine mammals. ECHINOPHTHIRIIDÆ
+
+aa. Legs fitted for walking or jumping; spiracles of abdomen usually
+    ventral; beak segmented.
+
+  b. Apex of head usually directed anteriorly; beak arising from its
+      apex; sides of the face remote from the front coxæ; first pair of
+      wings when present thickened at base, with thinner margins.
+      HETEROPTERA
+
+[Illustration: 159. Taxonomic details of Hemiptera-Heteroptera. (_a_)
+Dorsal aspect; (_b_) seta from bedbug; (_c_) wing of Heteropteron; (_d_)
+leg; (_e_) wing of Sinea.]
+
+    c. Front tarsi of one segment, spade-form (palæformes); beak short,
+        at most two-segmented; intermediate legs long, slender;
+        posterior pair adapted for swimming. CORIXIDÆ
+
+    cc. Front tarsi rarely one-segmented, never spade-form; beak free,
+        at least three-segmented.
+
+      d. Pulvilli wanting.
+
+        e. Hemelytra usually with a distinct clavus (fig. 159), clavus
+            always ends behind the apex of the scutellum, forming the
+            commissure. (Species having the wings much reduced or
+            wanting should be sought for in both sections.)
+
+          f. Antennæ very short; meso- and metasternum composite; eyes
+              always present.
+
+            g. Ocelli present; beak four-segmented. OCHTERIDÆ and
+                NERTHRIDÆ.
+
+            gg. Ocelli wanting; antennæ more or less hidden in a groove.
+
+              h. Anterior coxæ inserted at or near anterior margin of
+                  the prosternum; front legs raptorial; beak
+                  three-segmented BELOSTOMIDÆ (with swimming legs),
+                  NEPIDÆ, NAUCORIDÆ.
+
+                i. Metasternum without a median longitudinal keel;
+                    antennæ always four-segmented.
+
+                  j. Beak short, robust, conical; the hairy fleck on the
+                      corium elongate, large, lying in the middle
+                      between the inner angle of the membrane and the
+                      outer vein parallel to the membrane margin;
+                      membrane margin S-shaped.
+
+                    k. The thick fore femur with a relatively deep
+                        longitudinal furrow to receive the tibia.
+                        Several American species (fig. 19f.). BELOSTOMA
+                        (= Lethocerus Mayer)
+
+                    kk. The less thickened fore femur without such a
+                        furrow. B. GRISEUS. BENACUS Stäl.
+
+                  jj. Beak slender, cylindrical; the hairy spot on the
+                      corium rounded lying next to the inner angle of
+                      the membrane.
+
+                    k. Membrane large, furrow of the embolium broadened.
+                        _Z. aurantiacum_, _fluminea_, etc. _Zaitha_
+
+                    kk. Membrane very short; furrow of embolium not
+                        broadened. Western genus. _Pedinocoris_
+
+              ii. Metasternum with a long median longitudinal keel.
+                  Southwestern forms. _Abedus ovatus_ and _Deniostoma
+                  dilatato_
+
+            hh. Anterior coxæ inserted at the posterior margin of the
+                prosternum; legs natatorial. Back swimmers (fig. 19 b.).
+                NOTONECTIDÆ
+
+              i. Apices of the hemelytra entire; the three pairs of legs
+                  similar in shape; beak three-segmented; abdomen not
+                  keeled or hairy. _Plea_ Leach
+
+              ii. Apices of hemelytra notched; legs dissimilar; beak
+                  four-segmented; abdomen keeled and hairy.
+
+                j. Hemelytra usually much longer than the abdomen;
+                    fourth segment of the antenna longer than the third
+                    segment; hind tarsi with claws. _Bueno_ Kirk.
+
+                jj. Hemelytra but little longer than the abdomen; fourth
+                    segment of the antenna shorter than the third
+                    segment; hind tarsi without claws (fig. 19b).
+                    NOTONECTA L.
+
+          ff. Antennæ longer than the head; or if shorter, then the eyes
+              and ocelli absent.
+
+            g. Eyes, ocelli, and scutellum wanting; beak
+                three-segmented; head short; hemelytra always short;
+                membrane wanting. Insects parasitic on bats. POLYCTENIDÆ
+
+            gg. Eyes present.
+
+              h. First two antennal segments very short, last two long,
+                  pilose, third thickened at the base; ocelli present,
+                  veins of the hemelytra forming cells. DIPSOCORIDÆ (=
+                  CERATOCOMBIDÆ) including SCHIZOPTERIDÆ.
+
+              hh. Third segment of the antenna not thickened at the
+                  base, second as long or longer than the third, rarely
+                  shorter.
+
+                i. Posterior coxæ hinged (cardinate), if rarely
+                    rotating, the cuneus is severed, the membrane is one
+                    or two-celled, and the meso- and metasternum are
+                    composite.
+
+                  j. Ocelli absent, clypeus dilated toward the apex;
+                      hemelytra always short, membrane wanting. Species
+                      parasitic. Bed bugs, etc. CIMICIDÆ
+
+                    k. Beak short, reaching to about the anterior coxæ;
+                        scutellum acuminate at the apex; lateral margin
+                        of the elytra but little reflexed, apical margin
+                        more or less rounded; intermediate and posterior
+                        coxæ very remote.
+
+                      l. Body covered with short hairs, only the sides
+                          of the pronotum and the hemelytra fringed with
+                          longer hairs; antennæ with the third and
+                          fourth segments very much more slender than
+                          the first and second; pronotum with the
+                          anterior margin very _deeply sinuate_. CIMEX
+                          L.
+
+                        m. Sides of the pronotum widely dilated, broader
+                            than the breadth of one eye, and densely
+                            fringed with backward curved hairs; apical
+                            margin of the hemelytra nearly straight,
+                            rounded toward the interior or exterior
+                            angles.
+
+                          n. Body covered with very short hairs; second
+                              segment of the antenna shorter than the
+                              third; sides of the pronotum feebly
+                              reflexed, fringed with shorter hairs than
+                              the breadth of one eye; hemelytra with the
+                              commissural (inner) margin rounded and
+                              shorter than the scutellum, apical margin
+                              rounded towards the interior angle. The
+                              common bed bug (fig. 19h). C. LECTULARIUS
+                              Linn
+
+                          nn. Body covered with longer hairs; second and
+                              third segments of the antenna of equal
+                              length; side of the pronotum narrowly, but
+                              distinctly, reflexed, fringed with longer
+                              hairs than the breadth of one eye;
+                              hemelytra with the commissural margin
+                              straight and longer than the scutellum,
+                              apical margin rounded towards the exterior
+                              angle. Species found on bats in various
+                              parts of the United States. _C.
+                              pillosellus_ Hov.
+
+                        mm. Sides of the pronotum neither dilated, nor
+                            reflexed, fringed with less dense and nearly
+                            straight hairs; hemelytra with the apical
+                            margin distinctly rounded. Parasitic on man,
+                            birds and bats. Occurs in the old world,
+                            Brazil and the West Indies. C. HEMIPTERUS
+                            Fabr. (= rotundatus)
+
+                      ll. Body clothed with rather longer silky hairs;
+                          third and fourth segments of the antenna
+                          somewhat more slender than the first and
+                          second; anterior margin of the pronotum _very
+                          slightly sinuate_ or nearly straight in the
+                          middle, produced at the lateral angles. This
+                          is the species which in American collections
+                          is known as _C. hirundinis_, the latter being
+                          an old world form. It is found in swallows
+                          nests. O. VICARIUS. OECIACUS Stäl
+
+                    kk. Beak long, reaching to the posterior coxæ;
+                        scutellum rounded at the apex; lateral margins
+                        of the elytra strongly reflexed, apical margin
+                        slightly sinuate toward the middle; intermediate
+                        and posterior coxæ sub-contiguous. This species
+                        infests poultry in southwest United States and
+                        in Mexico. H. INODORUS. HÆMATOSIPHON Champ.
+
+[Illustration: 160. Pselliopsis (Milyas) cinctus (×2). After C. V.
+Riley.]
+
+                  jj. Ocelli present, if rarely absent in the female,
+                      then the tarsus has two segments; or if with three
+                      tarsal segments, the wing membrane with one or two
+                      cells.
+
+                    k. Beak four-segmented, or with two-segmented tarsi.
+                        ISOMETOPIDÆ, MICROPHYSIDÆ, and some CAPSIDÆ.
+
+                    kk. Beak three-segmented.
+
+                      l. Hemelytra with embolium; head horizontal, more
+                          or less conical; membrane with one to four
+                          veins, rarely wanting. ANTHOCORIDÆ
+
+                        Several species of this family affecting man
+                            have been noted, ANTHOCORIS KINGI and
+                            CONGOLENSE, from Africa and LYCTOCORIS
+                            CAMPESTRIS from various parts of the world.
+                            LYCTOCORIS FITCHII Reuter (fig. 19 j), later
+                            considered by Reuter as a variety of L.
+                            CAMPESTRIS, occurs in the United States.
+
+                      ll. Hemelytra without embolium. Superfamily
+                          ACANTHIOIDEA (= SALDÆ Fieber and LEPTOPODÆ
+                          Fieber)
+
+                ii. Posterior coxæ rotating.
+
+                  j. Claws preapical; aquatic forms. GERRIDÆ and VELIADÆ
+
+                  jj. Claws apical.
+
+                    k. Prosternum without stridulatory sulcus (notch for
+                        beak).
+
+                      l. Tarsus with three segments; membrane with two
+                          or three longitudinal cells from which veins
+                          radiate; rarely with free longitudinal veins
+                          (Arachnocoris) or veins nearly obsolete
+                          (Arbela); clavus and corium coriaceous; ocelli
+                          rarely absent. NABIDÆ
+
+                        REDUVIOLUS (= CORISCUS) SUBCOLEOPTRATUS (fig. 19
+                            g), a species belonging to this family,
+                            occurring in the United States, has been
+                            accused of biting man. This insect is flat,
+                            of a jet black color, bordered with yellow
+                            on the sides of the abdomen, and with
+                            yellowish legs. It is predaceous, feeding on
+                            other insects.
+
+                      ll. With other combinations of characters.
+                          HYDROMETRIDÆ, HENICOCEPHALIDÆ, NÆOGEIDÆ,
+                          MESOVELIADÆ, JOPPEICIDÆ
+
+                    kk. Prosternum with stridulatory sulcus (notch for
+                        beak); with three segments, short, strong.
+
+                      l. Antennæ filiform or sometimes more slender
+                          apically, geniculate; wing membrane with two
+                          or three large basal cells; scutellum small or
+                          moderate REDUVIIDÆ
+
+                        For a key to the genera and species see next
+                            page.
+
+                      ll. Last antennal segment clavate or fusiform; win
+                          membrane with the veins often forked and
+                          anastomosing; scutellum large; tarsi each with
+                          two segments; fore legs strong. (= PHYMATIDÆ)
+                          MACROCEPHALIDÆ
+
+        ee. Clavus noticeably narrowed towards the apex, never extending
+            beyond the scutellum, the two not meeting to form a
+            commissure; head horizontal, much prolonged between the
+            antennæ, on each side with an antennal tubercle, sometimes
+            acute; ocelli absent; meso- and metasternum simple; tarsi
+            each with two segments; body flattened (fig. 19c). ARADIDÆ,
+            including DYSODIIDÆ.
+
+      dd. Pulvilli present (absent in one Australian family
+          THAUMATOCORIDÆ in which case there is a membranous appendage
+          at the tip of the tibia). CAPSIDÆ (= MIRIDÆ),[G] _Eotrechus_
+          (in family GERRIDÆ), NÆOGAIDÆ, TINGITIDÆ, PIESMIDÆ,
+          MYODOCHIDÆ, CORIZIDÆ, COREIDÆ, ALYDIDÆ, PENTATOMIDÆ,
+          SCUTELLERIDÆ, etc.
+
+  bb. Apex of head directed ventrally, beak arising from the hinder part
+      of the lower side of the head; sides of face contiguous to the
+      front coxæ; first pair of wings, when present, of uniform
+      thickness. Cicadas, scale insects, plant lice (Aphids),
+      spittle-insects, leaf hoppers, etc. HOMOPTERA
+
+
+REDUVIIDÆ OF THE UNITED STATES
+
+(Adapted from a key given by Fracker).
+
+a. Ocelli none; wings and hemelytra always present in the adults; no
+    discoidal areole in the corium near the apex of the clavus.
+    _Orthometrops decorata_, _Oncerotrachelus acuminatus_, etc.,
+    Pennsylvania and south. _Sarcinæ_
+
+aa. Ocelli present in the winged individuals; anterior coxæ not as long
+    as the femora.
+
+  b. Hemelytra without a quadrangular or discoidal areole in the corium
+      near the apex of the clavus.
+
+    c. Ocelli not farther cephalad than the caudal margins of the eyes;
+        segment two of the antenna single.
+
+      d. Thorax usually constricted caudad of the middle; anterior coxæ
+          externally flat or concave. PIRATINÆ
+
+        e. Middle tibiæ without spongy fossa, head long, no lateral
+            tubercle on neck. _S. stria_, Carolina, Ill., Cal.
+            _Sirthenia_ Spinola
+
+        ee. Middle tibiæ with spongy fossa; fore tibiæ convex above;
+            neck with a small tubercle on each side.
+
+          f. Apical portion of anterior tibiæ angularly dilated beneath,
+              the spongy fossa being preceded by a small prominence.
+              MELANOLESTES Stäl
+
+            g. Black, with piceous legs and antennæ. N. E. States (fig.
+                19a) M. PICIPES
+
+            gg. Sides, and sometimes the whole dorsal surface of the
+                abdomen red. Ill., and southward. M. ABDOMINALIS
+
+          ff. Tibiæ not dilated as in "f"; spongy fossa elongate;
+              metapleural sulci close to the margin. R. BIGUTTATUS (fig.
+              22). South RASAHUS A. and S.
+
+      dd. Thorax constricted in the middle or cephalad of the middle;
+          anterior tarsi each three-segmented.
+
+        e. Apex of the scutellum narrow, without spines or with a single
+            spine REDUVIINÆ
+
+          f. Antennæ inserted in the lateral or dorso-lateral margins of
+              the head; antenniferous tubercles slightly projecting from
+              the sides of the head; head produced strongly cephalad;
+              ocelli at least as far apart as the eyes.
+
+            g. Antennæ inserted very near the apex of the head; segments
+                one and three of the beak short, segment two nearly four
+                times as long as segment one. R. PROLIXUS. W. I.
+                RHODNIUS Stäl
+
+            gg. Antennæ inserted remote from the vertex of the head.
+
+              h. Body slightly hairy; pronotum distinctly constricted;
+                  angles distinct; anterior lobe four-tuberculate, with
+                  the middle tubercles large and conical. _M.
+                  phyllosoma_, large species from the southwest.
+                  _Meccus_ Stäl
+
+              hh. Body smooth, margin of the pronotum sinuous, scarcely
+                  constricted; anterior lobe lined with little
+                  tubercles. CONORHINUS Lap.
+
+                i. Surface of the pronotum and prosternum more or less
+                    granular.
+
+                  j. Eyes small, head black; body very narrow, a fifth
+                      as wide as long; beak reaches the middle of the
+                      prosternum. California. C. PROTRACTUS
+
+                  jj. Eyes large, head fuscous; body at least a fourth
+                      as wide as long. Southern species. _C.
+                      rubrofasciatus_
+
+                ii. Pronotum and prosternum destitute of granules.
+
+                  j. Border of abdomen entirely black except for a
+                      narrow yellowish spot at the apex of one segment.
+                      Texas. _C. gerstaeckeri_
+
+                  jj. Border of abdomen otherwise marked.
+
+                    k. Beak slender, joints one and two slightly pilose,
+                        two more than twice as long as one; tubercles at
+                        the apical angles of the pronotum slightly
+                        acute, conical. Md. to Ill. and south. The
+                        masked bed bug hunter (fig. 71). C. SANGUISUGUS
+
+                    kk. Beak entirely pilose, joint two a third longer
+                        than joint one; joint one much longer than
+                        three; tubercles at the apical angles of
+                        pronotum slightly elevated, obtuse. Ga., Ill.,
+                        Tex., Cal. _C. variegatus_
+
+          ff. Antenna inserted on top of the head between margins, close
+              to the eyes; antenniferous tubercles not projecting from
+              the side of the head.
+
+            g. Anterior lobe of the pronotum with a bispinous or
+                bituberculate disc; femora unarmed. _S. arizonica_, _S.
+                bicolor_. Southwestern species. _Spiniger_ Burm.
+
+            gg. Disc of pronotum unarmed; apex of scutellum produced
+                into a spine; ocelli close to the eyes; eyes large and
+                close together. REDUVIUS Lamarck
+
+              h. Color piceous. Widely distributed in the United States.
+                  (Fig. 20). R. PERSONATUS
+
+              hh. More or less testaceous in color. Southwestern states.
+                  R. SENILIS
+
+        ee. Apex of scutellum broad, with two or three spines.
+            ECTRICHODIINÆ
+
+          f. First segment of the antenna about as long as the head. _E.
+              cruciata_ Pa. and south; _E. cinctiventris_, Tex. and Mex.
+              _Ectrichodia_ L. et S.
+
+          ff. First segment of the antennæ short. _P. æneo-nitens_.
+              South. _Pothea_ A. et S.
+
+    cc. Ocelli cephalad of the hind margins of the eyes; first segment
+        of the antennæ stout, second segment divided into many smaller
+        segments. South and west. _Homalocoris maculicollis_, and
+        _Hammatocerus purcis_. HAMMATOCERINÆ
+
+  bb. Hemelytra with a quadrangular or discoidal areole in the corium
+      near the apex of the clavus (fig. 159e).
+
+    c. Anal areole of the membrane not extending as far proximad as the
+        costal areole; basal segment of the antenna thickened, porrect;
+        the other segments slender, folding back beneath the head and
+        the first segment STENOPODINÆ
+
+      d. Head armed with a ramous or furcate spine below each side,
+          caudad of the eyes.
+
+        e. First segment of the antenna thickened, apex produced in a
+            spine beyond the insertion of the second segment. Species
+            from Va., Ill. and south. _Pnirontis_ Stäl.
+
+        ee. First segment of the antenna not produced beyond the
+            insertion of the second segment. _Pygolampis_, N. E. states
+            and south; _Gnathobleda_, S. W. and Mex.
+
+      dd. Head unarmed below or armed with a simple spine; rarely with a
+          subfurcate spine at the side of the base. Carolina, Missouri
+          and south. _Stenopoda_, _Schumannia_, _Diaditus_, _Narvesus_,
+          _Oncocephalus_
+
+    cc. Anal areole of membrane extending farther proximad than the
+        costal areole.
+
+      d. Ocelli farther apart than the eyes. _A. crassipes_, widely
+          distributed in the United States; other species occur in the
+          southwest. _Apiomerus_ Hahn.
+
+      dd. Ocelli not so far apart as the eyes. ZELINÆ
+
+        e. Sides of mesosternum without a tubercle or fold in front.
+
+          f. Fore femur as long as or longer than the hind femur; first
+              segment of the beak much shorter than the second. _Z.
+              audax_, in the north eastern states; other species south
+              and west. _Zelus_ Fabr.
+
+          ff. Fore femur shorter than the hind femur, rarely of equal
+              length, in this case the first segment of the beak as long
+              or longer than the second.
+
+            g. First segment of the beak shorter than the second; fore
+                femur a little shorter than the hind femur; the first
+                segment of the beak distinctly longer than the head
+                before the eyes. _P. cinctus_ a widely distributed
+                species (fig. 160). _P. punctipes_, _P. spinicollis_,
+                Cal., Mex. (= _Milyas_) _Pselliopus_ Berg.
+
+            gg. First segment of the beak as long or longer than the
+                second.
+
+              h. Pronotum armed with spines on the disc.
+
+                i. Juga distinctly prominent at the apex and often acute
+                    or subacute; fore femur distinctly thickened;
+                    hemelytra usually not reaching the apex of the
+                    abdomen. _Fitchia aptera_, N. Y., south and west;
+                    _F. spinosula_, South; _Rocconata annulicornis_,
+                    Texas, etc.
+
+                ii. Juga when prominent, obtuse at apex; eyes full width
+                    of the head; fore femur not thickened; pronotum with
+                    four spines on posterior lobe. _R. taurus_, Pa.,
+                    south and west. _Repipta_ Stäl.
+
+              hh. Pronotum unarmed on the disc.
+
+                i. Spines on each apical angle of the penultimate
+                    abdominal segment. _A. cinereus_, Pa., and south.
+                    _Atrachelus_ A. et S.
+
+                ii. Apical angle of the penultimate abdominal segment
+                    unarmed. _Fitchia_ (in part); _Castolus ferox_,
+                    Arizona.
+
+        ee. Sides of the mesosternum with a tubercle or fold in front at
+            the hind angles of the prosternum; first segment of the beak
+            longer than the part of the head cephalad of the eyes.
+
+          f. Fore femur thickened, densely granulated; hind femur
+              unarmed.
+
+[Illustration: 161. Taxonomic details of Diptera. (_a_) Ventral aspect
+of abdomen of Cynomyia; (_b_) antenna of Tabanus; (_c_) ventral aspect
+of abdomen of Chortophila; (_d_) ventral aspect of abdomen of Stomoxys;
+(_e_) claw of Aedes (Culex) sylvestris, male; (_f_) claw of Hippoboscid;
+(_g_) foot of dipterous insect showing empodium developed pulvilliform;
+(_h_) hind tarsal segment of Simulium vittatum, female; (_i_) foot of
+dipterous insect showing bristle-like empodium.]
+
+            g. Fore tibiæ each with three long spines on the ventral
+                side. _S. diadema_ (fig. 159e), a widely distributed
+                species; and several southwestern species. _Sinea_ A. et
+                S.
+
+            gg. Fore tibiæ unarmed. _A. multispinosa_, widely
+                distributed; _A. tabida_, Cal. _Acholla_ Stäl.
+
+          ff. Fore femur unarmed, rarely a little thickened, a little
+              granulated.
+
+            g. Pronotum produced caudad over the scutellum, with a high
+                mesal tuberculate ridge (fig. 19e). A. CRISTATUS. N. Y.
+                to Cal. and south. ARILUS Hahn.
+
+            gg. Caudal lobe of the pronotum six sided, neither elevated
+                nor produced caudad. _H. americanus_, Southwest; also
+                several W. I. and Mexican genera. HARPACTOR Lap.
+
+
+DIPTERA (Mosquitoes, Midges, Flies)
+
+a. Integument leathery, abdominal segments indistinct; wings often
+    wanting; parasitic forms. PUPIPARA
+
+  b. Head folding back on the dorsum of the thorax; wingless flies
+      parasitic on bats. Genus _Nycteribia_. NYCTERIBIIDÆ
+
+  bb. Head not folding back upon the dorsum of the thorax; flies either
+      winged or wingless; parasitic on birds and on bats and other
+      mammals.
+
+    c. Antennæ reduced, wings when present, with distinct parallel veins
+        and outer crossveins; claws simple; palpi leaf-like, projecting
+        in front of the head. Flies chiefly found on bats. Several
+        genera occur in North America. STREBLIDÆ
+
+[Illustration: 162. Hippobosca equina, ×4. After Osborn.]
+
+    cc. Antennæ more elongate, segments more or less distinctly
+        separated; head sunk into an emargination of the thorax; wings
+        when present with the veins crowded toward the anterior margin;
+        palpi not leaf-like. HIPPOBOSCIDÆ
+
+      d. Wings absent or reduced and not adapted for flight.
+
+        e. Wings and halteres (balancers) absent. _M. ovinus_, the sheep
+            tick. _Melophagus_ Latr.
+
+        ee. Wing reduced (or cast off), halteres present.
+
+          f. Claw bidentate; ocelli present. On deer after the wings are
+              cast off. _L. depressa_. _Lipoptena_ Nitsch
+
+          ff. Claw tridentate (fig. 161 f). On _Macropis_. _B.
+              femorata._ _Brachypteromyia_ Will.
+
+      dd. Wings present and adapted for flight.
+
+        e. Claws bidentate.
+
+          f. Ocelli present; head flat; wings frequently cast off. On
+              birds before casting of the wing. _Lipoptena_ Nitsch.
+
+          ff. Ocelli absent; head round; wings present. The horse tick
+              H. EQUINA may attack man (fig. 162). HIPPOBOSCA L.
+
+        ee. Claws tridentate (fig. 161 f.).
+
+          f. Anal cell closed at apical margin by the anal crossvein.
+
+            g. Ocelli absent. _Stilbometopa_ Coq.
+
+            gg. Ocelli present.
+
+              h. R_{4+5} does not form an angle at the crossvein. On
+                  birds. There is a record of one species of this genus
+                  attacking man. ORNITHOMYIA Latr.
+
+              hh. R_{4+5} makes an angle at the crossvein. _O.
+                  confluens_. _Ornithoica_ Rdi.
+
+          ff. Anal cell not closed by an anal crossvein. _Lynchia_,
+              _Pseudolfersia_, and _Olfersia_ are chiefly bird
+              parasites. The first mentioned genus is said to be the
+              intermediate host of _Hæmoproteus columbæ_.
+
+aa. Abdominal segments chitinous; not parasitic in the adult stage.
+
+  b. Antennæ with six or more segments and empodium not developed
+      pulvilliform; palpi often with four segments.
+
+    c. Ocelli present. BLEPHAROCERIDÆ, RHYPHIDÆ, BIBIONIDÆ,
+        MYCETOPHILIDÆ, besides some isolated genera of other families.
+
+    cc. Ocelli absent.
+
+      d. Dorsum of the thorax with a V-shaped suture; wings usually with
+          numerous veins; legs often very long and slender. Crane flies.
+          TIPULIDÆ
+
+      dd. Dorsum of the thorax without a V-shaped suture.
+
+        e. Not more than four longitudinal veins ending in the wing
+            margin; wing usually hairy: antennæ slender; coxæ not long;
+            tibiæ: without spurs, legs long and slender. Small, delicate
+            flies often called Gall gnats. CECIDOMYIIDÆ.
+
+        ee. More than four longitudinal veins ending in the wing margin.
+
+          f. The costal vein is not produced beyond the tip of the wing;
+              radius with not more than three branches.
+
+            g. Antennæ short, composed of ten or eleven closely united
+                segments; legs stout; body stout; abdomen oval; anterior
+                veins stout, posterior ones weak (fig. 163 b); eyes of
+                the male contiguous over the antennæ. Black flies,
+                buffalo flies, turkey gnats. Many North American
+                species, several of them notorious for their blood
+                sucking propensities. SIMULIIDÆ
+
+              h. Second joint of the hind tarsus with basal scale-like
+                  process and dorsal excision (fig. 161 h); radial
+                  sector not forked; no small cell at the base of the
+                  wing. _S. forbesi_, _jenningsi_, _johannseni_,
+                  _meridionale_, _piscicidium_, VENUSTUM, VITTATUM, etc.
+                  Widely distributed species (= EUSIMULIUM) SIMULIUM
+                  Latr.
+
+              hh. No basal scale-like process on the second joint of the
+                  hind tarsus; radial sector usually forked (fig. 163
+                  b).
+
+                i. Face broad, small basal cell of the wing present. _P.
+                    fulvum_, HIRTIPES, _mutatum_, PECUARUM, _pleurale_.
+                    PROSIMULIUM Roub.
+
+                ii. Face linear; small basal cell of the wing absent.
+                    One species, _P. furcatum_, from California.
+                    _Parasimulium_ Malloch
+
+            gg. Flies of a different structure.
+
+              h. Antennæ composed of apparently two segments and a
+                  terminal arista formed of a number of closely united
+                  segments. Rare flies with aquatic larvæ.
+                  ORPHNEPHILIDÆ
+
+              hh. Antennæ of six to fifteen segments, those of the male
+                  usually plumose; legs frequently slender and wings
+                  narrow CHIRONOMIDÆ
+
+                i. Media forked (except in the European genus
+                    _Brachypogon_); thorax without longitudinal fissure
+                    and not produced over the head (except in four
+                    exotic genera); antennæ usually fourteen-jointed in
+                    both sexes; fore tibia with a simple comb of setulæ,
+                    hind tibia with two unequal combs, middle tibia
+                    without comb. CERATOPOGONINÆ
+
+                  j. Thorax produced cap-like over the head, wing narrow
+                      and very long. _Jenkinsia_, _Macroptilum_ and
+                      _Calyptopogon_, eastern hemisphere;
+                      _Paryphoconus_, Brazil.
+
+                  jj. Thorax not produced over the head.
+
+                    k. Eyes pubescent, empodium well developed, or if
+                        short then R_{2+3} distinct and crossvein-like
+                        or the branches of R coalescent; r-m crossvein
+                        present; fore femora not thickened; wing either
+                        with appressed hairs or with microscopic erect
+                        setulæ _Dasyhelea_ Kieff.
+
+                    kk. Eyes bare, or otherwise differing from the
+                        foregoing.
+
+                      l. Empodium well developed, nearly as long as the
+                          claws and with long hairs at the base; femora
+                          and fifth tarsal segments unarmed, i.e.
+                          without spines or stout setæ; fourth tarsal
+                          segment cylindrical.
+
+                        m. Wing with erect and microscopic setulæ.
+                            Widely distributed. (= Atrichopogon)
+                            _Ceratopogon_ Meig.
+
+                        mm. Wing with long and depressed hairs. Widely
+                            distributed. _Forcipomyia_
+
+                          n. Hind metatarsus shorter or not longer than
+                              the following (i.e. the second tarsal)
+                              segment. Subgenus _Prohelea_ Kieff
+
+                          nn. Hind metatarsus longer than the following
+                              segment. Subgenus _Forcipomyia_ Meig.
+
+                      ll. Empodium short, scarcely reaching the middle
+                          of the claws, or vestigial.
+
+                        m. R-m crossvein wanting.
+
+                          n. Palpi four segmented; inferior fork of the
+                              media obliterated at the base. Australia.
+                              _Leptoconops_ Skuse
+
+                          nn. Palpi three-segmented.
+
+                            o. Legs spinulose, tarsal claws of the
+                                female with a basal tooth or strong
+                                bristle, those of the male unequal, the
+                                anterior with a long sinuous tooth, the
+                                posterior with a short arcuate tooth.
+                                Italy. MYCTEROTYPUS Noé
+
+                            oo. Legs unarmed; no crossvein between the
+                                branches of the radius (fig. 163e). New
+                                Mexico. TERSESTHES Townsend
+
+                        mm. R-m crossvein present.
+
+                          n. Fore femora very much swollen, armed with
+                              spines below, fore tibia arcuate and
+                              applied closely to the inferior margin of
+                              the femur.
+
+                            o. R_{2+3} present, therefore cell R_1 and
+                                R_2 both present; wing usually fasciate.
+                                United States _Heteromyia_ Say.
+
+                            oo. R_{2+3} not distinct from R_{4+5}, hence
+                                cell R_3 obliterated. South America
+                                _Pachyleptus_ Arrib. (Walker)
+
+                          nn. Fore femur not distinctly swollen.
+
+                            o. R_{2+3} present therefore cells R_1 and
+                                R_3 both present, or if not, then the
+                                branches of the radius more or less
+                                coalescent, obliterating the cells.
+
+                              p. At least the tip of the wing with erect
+                                  setulæ; tip of R_{4+5} scarcely
+                                  attaining the middle of the wing,
+                                  empodium rather indistinct, not
+                                  reaching the middle of the claws, the
+                                  claws not toothed, equal, with long
+                                  basal bristle; legs without stout
+                                  setæ. Widely distributed. CULICOIDES
+                                  Latr.
+
+                                HÆMATOMYIDIUM and OECACTA are probable
+                                    synonyms of this.
+
+                              pp. Wings bare, if rarely with hair, then
+                                  the radius reaches beyond two-thirds
+                                  the length of the wing, or the femur
+                                  or fifth tarsal segment with stout
+                                  black spines.
+
+                                q. Media unbranched. Europe.
+                                    _Brachypogon_ Kieff
+
+                                qq. Media branched.
+
+                                  r. Hind femur much swollen and spined.
+                                      America and Europe. _Serromyia_
+                                      Meg.
+
+                                  rr. Hind femur not distinctly swollen.
+
+                                    s. Cell R_1 not longer than high;
+                                        fork of the media distad of the
+                                        crossvein; wing with microscopic
+                                        setulæ _Stilobezzia_ Kieff
+
+                                    ss. Cell R_1 elongate.
+
+                                      t. Femora unarmed. Widely
+                                          distributed. (= Sphaeromias
+                                          Kieff. 1913 not Curtis?).
+                                          JOHANNSENIELLA Will.
+
+                                      tt. Femora, at least in part, with
+                                          strong black spines. Widely
+                                          distributed. _Palpomyia_
+                                          Megerle
+
+                            oo. R_{2+3} coalescent with R_{4+5} hence
+                                cell R_3 is obliterated.
+
+                              p. In the female the lower branch of the
+                                  media with an elbow near its base
+                                  projecting proximad, the petiole of
+                                  the media coalescent with the basal
+                                  section of the radius, wing long and
+                                  narrow, radial sector ending near the
+                                  tip of the wing; venation of the male
+                                  as in _Bezzia_; front concave. United
+                                  States. _Stenoxenus_ Coq.
+
+                              pp. Venation otherwise, front not concave.
+
+                                q. Subcosta and R_1 more or less
+                                    coalescent with the costa; wing
+                                    pointed at the apex, much longer
+                                    than the body; antennæ fourteen
+                                    segmented, not plumose. India.
+                                    _Haasiella_ Kieff.
+
+                                qq. Subcosta and radius distinct from
+                                    the costa.
+
+                                  r. Abdomen petiolate. _Dibezzia_
+                                      Kieff.
+
+                                  rr. Abdomen not petiolate.
+
+                                    s. Head semi-globose; hind tarsi
+                                        unusually elongate in the
+                                        female; antennæ of the male not
+                                        plumose. Europe. _Macropeza_
+                                        Meigen.
+
+                                    ss. Head not globose, more or less
+                                        flattened in front; antennæ of
+                                        the male plumose. Widely
+                                        distributed. _Bezzia_ Kieff.
+
+                                      t. Fore femora, at least, armed
+                                          with stout spines below.
+                                          Subgenus _Bezzia_ Kieff.
+
+                                      tt. Femora unarmed. Subgenus
+                                          _Probezzia_ Kieff.
+
+                ii. Media of the wing simple, and otherwise not as in
+                    "i". To this group belong numerous Chironomid
+                    genera, none of which are known to be noxious to
+                    man.
+
+          ff. The costal vein apparently is continued around the hind
+              margin of the wing; radius with at least four branches.
+
+            g. Wing ovate pointed, with numerous veins; crossveins, if
+                evident, before the basal third of the wing; veins very
+                hairy; very small moth-like flies. PSYCHODIDÆ
+
+              h. With elongate biting proboscis; the petiole of the
+                  anterior forked cell of the wing (R_2) arises at or
+                  beyond the middle of the wing (fig. 163d). PHLEBOTOMUS
+                  Rdi.
+
+[Illustration: 163. Wings of Diptera. (_a_) Anopheles; (_b_)
+Prosimulium; (_c_) Johannseniella; (_d_) Phlebotomus (After Doerr and
+Russ); (_e_) Tersesthes (after Townsend); (_f_) Tabanus; (_g_)
+Symphoromyia; (_h_) Aphiochæta; (_i_) Eristalis; (_j_) Gastrophilus;
+(_k_) Fannia; (_l_) Musca.]
+
+              hh. With shorter proboscis; the petiole of the anterior
+                  forked cell arises near the base of the wing.
+                  _Psychoda_, _Pericoma_, etc.
+
+            gg. The r-m crossvein placed at or beyond the center of the
+                wing; wings not folded roof-like over the abdomen.
+
+              h. Proboscis short, not adapted for piercing; wings bare
+                  (DIXIDÆ); or wings scaled (CULICIDÆ, Subf.
+                  CORETHRINÆ).
+
+              hh. Proboscis elongate, adapted for piercing; wings
+                  scaled, fringed on the hind margin; antennæ of the
+                  male bushy plumose. Mosquitoes. CULICIDÆ (exclusive of
+                  CORETHRINÆ)
+
+                i. Metanotum without setæ.
+
+                  j. Proboscis strongly decurved; body with broad,
+                      appressed, metalescent scales; cell R_2 less than
+                      half as long as its petiole; claws of female
+                      simple, some of the claws of the male toothed.
+                      Several large southern species believed to feed
+                      only on nectar of flowers. _Megarhinus_ R. D.
+
+                  jj. Proboscis straight or nearly so, or otherwise
+                      different.
+
+                    k. Scutellum evenly rounded, not lobed; claws simple
+                        in both sexes. ANOPHELES Meig.
+
+                      l. Abdomen with clusters of broad outstanding
+                          scales along the sides; outstanding scales on
+                          the veins of the wing rather narrow,
+                          lanceolate; upper side of the thorax and
+                          scutellum bearing many appressed lanceolate
+                          scales. Florida and southward (CELLIA).
+
+                        m. Hind feet from the middle of the second
+                            segment largely or wholly snow white.
+
+                          n. With a black band at the base of the last
+                              segment of each hind foot. A.
+                              ALBIMANUS*[H] and TARSIMACULATA*
+
+                          nn. Without such a band A. ARGYRITARSIS*
+
+                        mm. Hind feet black, mottled with whitish and
+                            with bands of the same color at the sutures
+                            of the segments. W. I. A. MACULIPES
+
+                      ll. Abdomen without such a cluster of scales;
+                          outstanding scales of the wing veins rather
+                          narrow, lanceolate; tarsi wholly black.
+
+                        m. Deep black, thorax obscurely lined with
+                            violaceous, especially posteriorly; head,
+                            abdomen and legs black; no markings on the
+                            pleura; abdomen without trace of lighter
+                            bindings; wing scales outstanding, uniform,
+                            not forming spots, though little thicker at
+                            the usual points indicating the spottings.
+                            Florida. A. ATROPUS
+
+                        mm. Otherwise marked when the wings are
+                            unspotted.
+
+                          n. Wings unspotted.
+
+                            o. Petiole of the first forked cell (R_2)
+                                more than a third the length of the
+                                cell. Mississippi valley. A. WALKERI
+
+                            oo. Petiole of the first forked cell a third
+                                the length of the cell. Md. A. BARBERI
+
+                          nn. Wings spotted.
+
+                            o. Front margin of the wings with a patch of
+                                whitish and yellow scales at a point
+                                about two-thirds or three-fourths of the
+                                way from base to apex of wing.
+
+                              p. Veins of the wing with many broad
+                                  obovate outstanding scales; thorax
+                                  with a black dot near the middle of
+                                  each side. W. I. A. GRABHAMI*
+
+                              pp. The outstanding scales of the wings
+                                  rather narrow, lanceolate.
+
+                                q. Scales of the last vein of the wings
+                                    white, those at each end black;
+                                    R_{4+5} black scaled, the extreme
+                                    apex white scaled. Widely
+                                    distributed north and south (fig.
+                                    131). A. PUNCTIPENNIS
+
+                                  A dark variety from Pennsylvania has
+                                      been named A. PERPLEXENS.
+
+                                qq. Scales of the last vein of the wing
+                                    white, those at its apex black;
+                                    R_{4+5} white scaled and with two
+                                    patches of black scales. South and
+                                    the tropics. A. FRANCISCANUS and
+                                    PSEUDOPUNCTIPENNIS*
+
+                            oo. Front margin of the wings wholly black
+                                scaled.
+
+                              p. Last (anal) vein of the wings white
+                                  scaled with three patches of black
+                                  scales (fig. 132). New Jersey to
+                                  Texas. A. CRUCIANS*
+
+                              pp. Last vein of the wings wholly black
+                                  scaled.
+
+                                q. Widely distributed north and south
+                                    (fig. 130), (= MACULIPENNIS). A.
+                                    QUADRIMACULATUS*
+
+                                qq. Distributed from Rocky Mountains
+                                    westward. A. OCCIDENTALIS
+
+                    kk. Scutellum distinctly trilobed.
+
+                      l. Cell R_2 less than half as long as its petiole;
+                          thorax with metallic blue scales; median lobe
+                          of the scutellum not tuberculate; few small
+                          species which are not common. URANOTÆNIA
+                          Arrib.
+
+                      ll. Cell R_2 nearly or quite as long as its
+                          petiole, or otherwise distinct.
+
+                        m. Femora with erect outstanding scales; occiput
+                            broad and exposed. Large species. P.
+                            CILIATA. P. HOWARDI PSOROPHORA R. D.
+
+                        mm. Femora without erect scales.
+
+                          n. Clypeus bearing several scales or hairs,
+                              scutellum with broad scales only; back of
+                              head with broad scales; scales along the
+                              sides of the mesonotum narrow; some or the
+                              claws toothed; thorax marked with a pair
+                              of silvery scaled curved stripes; legs
+                              black with white bands at the bases of
+                              some of the segments (fig. 134). Yellow
+                              Fever mosquito. AEDES (= STEGOMYIA)
+                              CALOPUS.
+
+                          nn. With another combination of characters.
+                              Numerous species of mosquitoes belonging
+                              to several closely related genera, widely
+                              distributed over the country. (_Culex_,
+                              _Aedes_, _Ochlerotatus_, etc.). CULEX in
+                              the wide sense.
+
+                ii. Metanotum with setæ. _Wyeomyia_ (found in the United
+                    States); and related tropic genera.
+
+  bb. Antennæ composed of three segments with a differentiated style or
+      bristle; third segment sometimes complex or annulate, in which
+      case the empodium is usually developed like the pulvilli, i.e.,
+      pad-like (fig. 161 g).
+
+    c. Empodium developed pad-like (pulvilliform) i.e., three nearly
+        equal membranous appendages on the underside of the claw (fig.
+        161g).
+
+      d. Squamæ, head, and eyes large; occiput flattened or concave;
+          third segment of the antennæ with four to eight annuli or
+          segments, proboscis adapted for piercing; body with fine
+          hairs, never with bristles; middle tibia with two spurs; wing
+          venation as figured (fig. 163f); marginal vein encompasses the
+          entire wing. Horse flies, greenheads, deer flies, gad flies
+          TABANIDÆ[I]
+
+        e. Hind tibia with spurs at tip; ocelli usually present
+            (PANGONINÆ)
+
+          f. Third joint of the antennæ with seven or eight segments;
+              proboscis usually prolonged.
+
+            g. Each section the third antennal segment branched. Central
+                American species, _P. festæ_. _Pityocera_ G. T.
+
+            gg. Sections of the third antennal segment not branched.
+
+              h. Upper corner of the eyes in the female terminating in
+                  an acute angle; wings of both sexes dark anteriorly.
+                  _G. chrysocoma_, a species from the eastern states.
+                  _Goniops_ Ald.
+
+              hh. Upper corner of the eye in the female not so
+                  terminating; wings nearly uniform in color, or
+                  hyaline.
+
+                i. Proboscis scarcely extending beyond the palpi; front
+                    of the female wide; much wider below than above. S.
+                    W. States. _Apatolestes_ Will.
+
+                ii. Proboscis extending beyond the palpi.
+
+                  j. Wing with cell M_3 closed. Tropic America. (=
+                      _Diclisa_) _Scione_ Wlk.
+
+                  jj. Cell M_3 open; ocelli present or absent. Two or
+                      three eastern species; many south and west
+                      PANGONIA Rdi.
+
+          ff. Third segment of the antenna with five divisions; ocelli
+              present.
+
+            g. First and second segments of the antenna short, the
+                second only half as long as the first, three western
+                species. SILVIUS Rdi.
+
+            gg. First and second segments of the antenna long, the
+                second distinctly over half as long as the first. Deer
+                flies. Many species, widely distributed. CHRYSOPS Meig.
+
+        ee. Hind tibia without spurs; ocelli absent.
+
+          f. Third segment of antenna with four divisions, no tooth or
+              angulation; wings marked with rings and circles of darker
+              coloring; front of the female very wide. Widely
+              distributed. _H. americana_, _H. punctulata_. HÆMATOPOTA
+              Meig.
+
+          ff. Third segment of the antenna with five divisions (fig.
+              161b).
+
+            g. Third segment of the antenna not furnished with a tooth
+                or distinct angular projection.
+
+              h. Body covered with metallic scales; front of female of
+                  normal width; front and middle tibiæ greatly dilated.
+                  _L. lepidota_. _Lepidoselaga_ Macq.
+
+              hh. Body without metallic scales; antennæ not very long,
+                  the third segment not cylindrical, not situated on a
+                  projecting tubercle; front of the female narrow.
+                  South. _D. ferrugatus._ (= _Diabasis_) _Diachlorus_ O.
+                  S.
+
+            gg. Third segment of the antenna furnished with a tooth or a
+                distinct angular projection.
+
+              h. Hind tibiæ ciliate with long hairs. S. W. and tropics.
+                  _Snowiella_ and _Stibasoma_.
+
+              hh. Hind tibiæ not ciliate.
+
+                i. Species of slender build, usually with a banded
+                    thorax and abdomen; third segment of the antenna
+                    slender, the basal prominence long; wings mostly
+                    with brownish markings. Tropic America.
+                    _Dichelacera_ Macq.
+
+                ii. Species of a stouter build; third segment of the
+                    antenna stout, its basal process short (fig. 161b).
+                    Many species, widely distributed TABANUS L.
+
+      dd. With another group of characters.
+
+        e. Squamæ small, antennæ variable, thinly pilose or nearly bare
+            species, without distinct bristles; wing veins not crowded
+            anteriorly, R_4 and R_5 both present, basal cells large;
+            middle tibiæ at least with spurs. LEPTIDÆ
+
+          f. Flagellum of the antenna more or less elongated, composed
+              of numerous more or less distinct divisions. XYLOPHAGINÆ
+              and ARTHROCERATINÆ.
+
+          ff. Antennæ short, third segment simple, with arista or style;
+              face small, proboscis short LEPTINÆ
+
+            g. Front tibiæ each with one or two spurs, or if absent,
+                then no discal cell. _Triptotricha_, _Pheneus_,
+                _Dialysis_, _Hilarimorpha_.
+
+            gg. Front tibiæ without terminal spurs, discal cell present.
+
+              h. Hind tibiæ each with a single spur.
+
+                i. Anal cell open (fig. 163g); third antennal segment
+                    kidney-shaped with dorsal or subdorsal arista; first
+                    antennal segment elongate and thickened. About a
+                    dozen species have been described from the United
+                    States, of which at least one (S. PACHYCERAS) is
+                    known to be a vicious blood sucker. SYMPHOROMYIA
+                    Frauenf.
+
+                ii. Anal cell closed; third antennal segment not
+                    kidney-shaped. _Chrysopila_, _Ptiolina_, _Spania_.
+
+              hh. Hind tibiæ each with two spurs.
+
+                i. Third segment kidney-shaped, the arista subdorsal;
+                    anal cell closed. _Atherix_ Meig.
+
+                ii. Third segment of the antenna short and with terminal
+                    arista; anal cell open _Leptis_ Fabr. Two European
+                    species of this genus have been accused of blood
+                    sucking habits, but the record seems to have been
+                    based upon error in observation.
+
+        ee. With another combination of characters. STRATIOMYIIDÆ,
+            CYRTIDÆ, etc.
+
+    cc. Empodium bristlelike or absent.
+
+      d. Antennæ apparently two segmented, with three-segmented arista,
+          wings (rarely wanting) with several stout veins anteriorly,
+          the weaker ones running obliquely across the wing (fig. 163h);
+          small, quick running, bristly, humpbacked flies. Several
+          genera; APHIOCHÆTA, PHORA, TRINEURA, etc. PHORIDÆ
+
+      dd. Flies with other characters.
+
+        e. No frontal lunule above the base of the antennæ; both R_4 and
+            R_5 often present; third segment of the antenna often with a
+            terminal bristle. ASILIDÆ, MYDAIDÆ, APIOCERIDÆ, THEREVIDÆ,
+            SCENOPINIDÆ, BOMBYLIIDÆ, EMPIDIDÆ, DOLICHOPODIDÆ,
+            LONCHOPTERIDÆ.
+
+        ee. A frontal lunule above the base of the antennæ; third
+            segment of the antenna always simple, i.e., not ringed,
+            usually with a dorsal arista; R_4 and R_5 coalesced into a
+            simple vein.
+
+          f. A spurious vein or fold between the radius and the media,
+              rarely absent; the cell R_{4+5} closed at the apex by vein
+              M_1; few or no bristles on the body, none on the head;
+              flies frequently with yellow markings. ERISTALIS (fig.
+              163i), HELOPHILUS, and many other genera. SYRPHIDÆ
+
+          ff. No spurious vein present.
+
+            g. Body without bristles; proboscis elongate and slender,
+                often folding; front of both male and female broad.
+                CONOPIDÆ
+
+            gg. Bristles almost always present on head, thorax, abdomen
+                and legs.
+
+              h. Arista terminal; hind metatarsus enlarged, sometimes
+                  ornamented, hind tarsus more or less flattened beneath
+                  PLATYPEZIDÆ
+
+              hh. Flies having a different combination of characters.
+
+                i. Head large, eyes occupying nearly the entire head;
+                    cell R_{4+5} narrowed in the margin; small flies.
+                    PIPUNCULIDÆ
+
+                ii. Head and eyes not unusually large.
+
+                  j. Squamæ (tegulæ, or calyptræ, or alulæ) not large,
+                      often quite small, the lower one lacking, or at
+                      most barely projecting from below the upper one
+                      (antisquama); front of both male and female broad,
+                      the eyes therefore widely separated; posthumeral
+                      and intraalar macrochæta not simultaneously
+                      present; thorax usually without a complete
+                      transverse suture; postalar callus usually absent;
+                      the connectiva adjoining the ventral sclerites
+                      always visible; hypopleural macrochætæ absent;
+                      last section of R_{4+5} and M_{1+2} with but few
+                      exceptions nearly parallel; subcostal vein often
+                      wanting or vestigial or closely approximated to
+                      R_1; the latter often short, basal cells small,
+                      the posterior ones often indistinct or wanting;
+                      vibrissæ present or absent. ACALYPTRATE MUSCOIDEA
+
+                    k. Subcosta present, distinctly separated from R_1
+                        at the tip; R_1 usually ends distad of the
+                        middle of the wing; the small basal cells of the
+                        wing distinct.
+
+                      l. A bristle (vibrissa) on each side of the face
+                          near the margin of the mouth. CORDYLURIDÆ,
+                          SEPSIDÆ, PHYCODROMIDÆ, HETERONEURIDÆ,
+                          HELOMYZIDÆ.
+
+                      ll. No vibrissæ present.
+
+                        m. Head nearly spherical, cheeks broad and
+                            retreating; proboscis short; the cell R_5
+                            closed or narrowed in the margin; legs very
+                            long; tarsi shorter than the tibiæ. CALOBATA
+                            and other genera. MICROPEZIDÆ
+
+                        mm. Flies with another combination of
+                            characters. RHOPALOMERIDÆ, TRYPETIDÆ,
+                            ORTALIDÆ, SCIOMYZIDÆ.
+
+                    kk. Subcosta absent or vestigial, or if present,
+                        then apparently ending in the costa at the point
+                        where R_1 joins it; R_1 usually ends in the
+                        costa at or before the middle of the wing.
+
+                      l. Arista long plumose, or pectinate above; oral
+                          vibrissæ present; anal cell complete; costa
+                          broken at the apex of R_1. DROSOPHILA,
+                          PHORTICA, and other genera. DROSOPHILIDÆ
+
+                      ll. With another combination of characters.
+
+                        m. The cell M and first M_2 not separated by a
+                            crossvein; anal cell absent; front bare or
+                            only bristly above; usually light colored
+                            flies. HIPPELATES, OSCINUS, and other
+                            genera. (See also m m m.) OSCINIDÆ
+
+                        mm. Cell M and cell first M_2 often separated by
+                            a crossvein; anal cell present, complete,
+                            though frequently small; scutellum without
+                            spines or protuberances; oral vibrissæ
+                            present; arista bare or short plumose; front
+                            bristly at vertex only; small dark flies.
+                            PIOPHILA (fig. 99), SEPSIS and other genera.
+                            SEPSIDÆ
+
+                        mmm. The GEOMYZIDÆ, AGROMYZIDÆ, PSILIDÆ,
+                            TRYPETIDÆ, RHOPALOMERIDÆ, BORBORIDÆ and
+                            DIOPSIDÆ differ in various particulars from
+                            either the OSCINIDÆ and the SEPSIDÆ noted
+                            above.
+
+                  jj. Squamæ well developed, usually large, the lower
+                      one frequently projecting from below the upper
+                      one; both posthumeral and intraalar macrochætæ
+                      present; thorax with a complete transverse suture;
+                      postalar callus present and separated by a
+                      distinct suture from the dorsum of the thorax;
+                      front of the female broad, of the male frequently
+                      narrow, the eyes then nearly or quite contiguous;
+                      the connectiva adjoining the ventral sclerites
+                      either visible or not; hypopleural macrochætæ
+                      present or absent; subcosta always distinct in its
+                      whole course, R_1 never short. CALYPTRATE
+                      MUSCOIDEA[J]
+
+                    k. Oral opening small, mouth parts usually much
+                        reduced or vestigial. This family is undoubtedly
+                        of polyphyletic origin but for convenience it is
+                        here considered as a single family. OESTRIDÆ.
+
+                      l. The costal vein ends at the tip of R_{4+5},
+                          M_{1+2} straight, not reaching the wing
+                          margin, hence cell R_5 wide open (fig. 163j);
+                          squamæ small; arista bare; ovipositor of the
+                          female elongate. Larvæ in the alimentary canal
+                          of horses, etc. GASTROPHILUS
+
+                        m. Posterior crossvein (m-cu) wanting; wings
+                            smoky or with clouds. Europe. G. PECORUM
+
+                        mm. Posterior crossvein (m-cu) present, at least
+                            in part.
+
+                          n. Wing hyaline with smoky median cross band,
+                              and two or three spots; posterior
+                              trochanters with hook in the male and a
+                              prominence in the female. World wide
+                              distribution. G. EQUI.
+
+                          nn. Wings without spots.
+
+                            o. Posterior crossvein (m-cu) distad of the
+                                anterior crossvein (r-m); legs,
+                                particularly the femora, blackish brown.
+                                Europe and North America. G.
+                                HÆMORRHOIDALIS
+
+                            oo. Posterior crossvein opposite or proximad
+                                of the anterior crossvein. Europe and
+                                North America. G. NASALIS
+
+                      ll. The costal vein ends at the tip of M_{1+2},
+                          M_{1+2} with a bend, the cell R_5 hence much
+                          narrowed in the margin, or closed.
+
+                        m. Proboscis geniculate, inserted in a deep
+                            slit; female without extricate ovipositor;
+                            arista either bare or plumose; squamæ large;
+                            facial grooves approximated below.
+
+                          n. Arista bare, short. Larvæ in rodents.
+                              Tropic America. _B. princeps_. _Bogeria_
+                              Austen
+
+                          nn. Arista pectinate above.
+
+                            o. Tarsi broadened and flattened, hairy,
+                                anal lobe of the wing large. Larvæ in
+                                rodents. A number of American species.
+                                _Cuterebra_.
+
+                            oo. Tarsi slender, not hairy; anal lobe of
+                                the wing moderate. Larvæ in man and
+                                other mammals. Tropic America. D.
+                                CYANIVENTRIS. DERMATOBIA Br.
+
+                        mm. Mouth parts very small, vestigial; arista
+                            bare.
+
+                          n. Facial grooves approximated below, leaving
+                              a narrow median depression or groove.
+
+                            o. Cell R_5 closed and petiolate, body
+                                nearly bare. Larvæ in the nasal cavities
+                                of the smaller Ungulates. The sheep bot
+                                fly. O. OVIS. Widely distributed OESTRUS
+                                L.
+
+                            oo. Cell R_5 narrowly open, body hairy.
+                                Larvæ parasitic on deer. Europe and
+                                America. _Cephenomyia_ Latr.
+
+                          nn. Facial grooves far apart, enclosing
+                              between them a broad shield-shaped
+                              surface; squamæ large; female with
+                              elongate ovipositor. Larvæ hypodermatic on
+                              Ungulates HYPODERMA Clark
+
+                            o. Palpi wanting; tibiæ thickened in the
+                                middle.
+
+                              p. Hair at apex of the abdomen yellow;
+                                  legs including femora yellowish brown.
+                                  H. DIANA
+
+                              pp. Hair at the apex of the abdomen
+                                  reddish yellow. Europe and America.
+
+                                q. Tibiæ and tarsi yellow; femora black.
+                                    H. LINEATA
+
+                                qq. Legs black with black hair; tips of
+                                    hind tibia and tarsi yellowish
+                                    brown. H. BOVIS
+
+                            oo. Palpi small, globular; tibiæ
+                                cylindrical, straight. On reindeer. _O.
+                                tarandi_ _Oedemagena_ Latr.
+
+                    kk. Oral opening of the usual size; mouth parts not
+                        vestigial.
+
+                      l. Hypopleurals wanting; if three sternopleurals
+                          are present the arrangement is 1:2;
+                          conjunctiva (fig. 161c) of the venter usually
+                          present; if the terminal section of M_{1+2} is
+                          bent it has neither fold nor appendage
+                          (ANTHOMYIIDÆ of Girschner).
+
+                        m. Sternopleurals wanting; M_{1+2} straight
+                            toward the apex, costa ends at or slightly
+                            beyond the tip of R_{4+5}; mouth parts
+                            vestigial. GASTROPHILINÆ. See OESTRIDÆ
+
+                        mm. Sternopleurals present, if rarely absent
+                            then differing in other characters.
+
+                          n. Caudal margin of the fifth ventral
+                              abdominal sclerite of the male deeply
+                              notched on the median line usually to
+                              beyond the middle; abdomen often
+                              cylindrical or linear; abdomen often with
+                              four to eight spots; eyes of the male
+                              usually widely separated; sternopleurals
+                              three, arranged in an equilateral
+                              triangle; subapical seta of the hind tibia
+                              placed very low; M_{1+2} straight; anal
+                              vein abbreviated; wings not rilled.
+                              _Cænosia_, _Caricea_, _Dexiopsis_,
+                              _Hoplogaster_, _Schœnomyia_, etc.
+                              (CŒNOSINÆ)[K]. ANTHOMYIIDÆ in part
+
+                          nn. Caudal margin of the fifth ventral
+                              abdominal sclerite of the male incurved,
+                              rarely deeply cleft, rarely entire, in a
+                              few genera deeply two or three notched;
+                              M_{1+2} straight or curved; abdomen
+                              usually short or elongate oval;
+                              sternopleurals, if three are present,
+                              arranged in the order 1:2 in a right
+                              triangle. (MUSCINÆ-ANTHOMYIINÆ of
+                              Girschner)
+
+                            o. M_{1+2} straight, hence cell R_5 not
+                                narrowed in the margin. ANTHOMYIIDÆ in
+                                part
+
+                              p. Underside of the scutellum more or less
+                                  sparsely covered with fine hairs; anal
+                                  vein nearly always reaches the hind
+                                  margin of the wing; extensor surface
+                                  of the hind tibiæ with a number of
+                                  stout setæ; squamæ often small and
+                                  equal. ANTHOMYIA, _Chortophila_,
+                                  _Eustalomyia_, _Hammomyia_,
+                                  _Hylemyia_, _Prosalpia_, _Pegomyia_,
+                                  etc. HYLEMYINÆ-PEGOMYINÆ
+
+                              pp. Underside of the scutellum bare; anal
+                                  vein does not reach the wing margin.
+
+                                q. First anal vein short, second anal
+                                    suddenly flexed upwards; hind tibiæ
+                                    each with one or two strong setæ on
+                                    the extensor surface. FANNIA (=
+                                    HOMALOMYIA), _CÅ“lomyia_,
+                                    _Choristoma_, _Euryomma_, _Azelia_,
+                                    etc. FANNINÆ-AZELINÆ
+
+                                qq. Anal veins parallel or divergent.
+
+                                  r. Setæ on the exterior surface of the
+                                      hind tibiæ wanting (except in
+                                      _Limnaricia_ and _CÅ“nosites_),
+                                      lower squama not broadened to the
+                                      margin of the scutellum.
+                                      _Leucomelina_, _Limnophora_,
+                                      _Limnospila_, _Lispa_, _Mydæa_,
+                                      _Spilogaster_, etc.
+                                      MYDÆINÆ-LIMNOPHORINÆ
+
+                                  rr. One (rarely more) seta on the
+                                      extensor surface of the hind
+                                      tibia; squamæ usually large and
+                                      unequal. HYDROTAEA, _Aricia_,
+                                      _Drymeia_, _Ophyra_, _Phaonia_ (=
+                                      _Hyetodesia_), _Pogonomyia_,
+                                      _Trichophthicus_, etc. ARICINÆ
+
+                            oo. M_{1+2} curved or bent, hence the cell
+                                R_5 more or less narrowed in the margin.
+                                (MUSCINÆ). MUSCIDÆ in part. See page 303
+                                for generic synopsis.
+
+                      ll. Hypopleurals present; when three
+                          sternopleurals are present the arrangement is
+                          2:1 or 1:1:1. (TACHINIDÆ of Girschner)
+
+                        m. Conjunctiva of the ventral sclerites of the
+                            abdomen present, frequently well developed,
+                            surrounding the sclerites.
+
+                          n. Mouth parts vestigial. OESTRIDÆ. See page
+                              297 for generic synopsis.
+
+                          nn. Mouth parts well developed.
+
+                            o. M_{1+2} straight, hence cell R_5 wide
+                                open in the margin; costa ending at the
+                                tip of R_5; three sternopleurals
+                                present; antennal arista plumose.
+                                _Syllegoptera_. Europe.
+                                (SYLLEGOPTERINÆ). DEXIIDÆ in part
+
+                            oo. M_{1+2} bent, hence cell R_5 narrowed in
+                                the margin; sternopleurals rarely
+                                wanting, usually 1:1 or 0:1; facial
+                                plate strongly produced below vibrissal
+                                angle like the bridge of the nose;
+                                antennal arista bare. Parasitic on
+                                Hemiptera and Coleoptera. _Allophora_,
+                                _Cistogaster_, _Clytia_, _Phasia_, etc.
+                                (PHASIINÆ) TACHINIDÆ in part.
+
+                        mm. Conjunctiva of the ventral sclerites
+                            invisible (fig. 161a).
+
+                          n. Second ventral sclerite of the abdomen
+                              lying with its edges either upon or in
+                              contact with the ventral edges of the
+                              corresponding dorsal sclerite.
+
+                            o. Outermost posthumeral almost always lower
+                                (more ventrad) in position than the
+                                presutural macrochæta; fifth ventral
+                                abdominal sclerite of the male cleft
+                                beyond the middle, often strongly
+                                developed; body color very frequently
+                                metallic green or blue, or yellow;
+                                arista plumose. (CALLIPHORINÆ) MUSCIDÆ
+                                in part.
+
+                              See page 303 for generic synopsis.
+
+                            oo. Outermost posthumeral macrochæta on
+                                level or higher (more dorsad) than the
+                                presutural macrochæta; arista bare,
+                                pubescent, or plumose only on the basal
+                                two-thirds; body coloring usually
+                                grayish (fig. 106). SARCOPHAGIDÆ
+
+                              p. Fifth ventral sclerite of the male
+                                  either wanting or with the caudal
+                                  margin straight; presutural intraalar
+                                  rarely present. (SARCOPHAGINÆ)
+
+                                q. Fifth ventral abdominal sclerite of
+                                    the male much reduced, the remaining
+                                    segments with straight posterior
+                                    margin, overlapping scale-like; in
+                                    the female only segment one and two
+                                    scale-like, the others wholly or in
+                                    part covered; sternopleurals usually
+                                    three or more. SARCOPHAGA and
+                                    related genera.
+
+                                qq. Fifth ventral sclerite of the male
+                                    plainly visible; sternopleurals
+                                    usually two. SARCOPHILA,
+                                    WOHLFAHRTIA, _Brachycoma_,
+                                    _Hilarella_, _Miltogramma_,
+                                    _Metopia_, _Macronychia_, _Nyctia_,
+                                    _Paramacronychia_, _Pachyphthalmus_,
+                                    etc.
+
+                              pp. Fifth ventral abdominal sclerite of
+                                  the male cleft to beyond the middle;
+                                  ventral sclerites usually visible,
+                                  shield-like. _Rhinophora_, _Phyto_,
+                                  _Melanophora_ RHINOPHORINÆ
+
+[Illustration: 164. Glossina palpalis. (×4.) After Austen.]
+
+                          nn. Second ventral abdominal sclerite as well
+                              as the others more or less covered,
+                              sometimes wholly, by the edges of the
+                              dorsal sclerite.
+
+                            o. The presutural intraalar wanting; ventral
+                                sclerites two to five nearly or quite
+                                covered by the edges of the
+                                corresponding dorsal sclerites; base of
+                                the antennæ usually at or below the
+                                middle of the eye; arista usually
+                                plumose; legs usually elongate;
+                                abdominal segments with marginal and
+                                often discal macrochætæ. DEXIIDÆ
+
+                            oo. Presutural intraalar present, if absent,
+                                then the ventral sclerites broadly
+                                exposed or the fifth ventral sclerite
+                                vestigial; base of the antennæ usually
+                                above the middle of the eye; arista
+                                bare; at least two posthumerals and
+                                three posterior intraalars present.
+                                Parasitic on caterpillars, etc.
+                                TACHINIDÆ
+
+
+SYNOPSIS OF THE PRINCIPAL GENERA OF THE MUSCIDÆ OF THE WORLD
+
+a. Proboscis long, directed forward, adapted for piercing, or oral
+    margin much produced, snout-like.
+
+  b. Oral margin produced snout-like; vibrissa placed high above the
+      oral margin; antennal arista either pectinate or more or less
+      plumose.
+
+    c. Antennal arista short or long-plumose; neither sex with distinct
+        orbital bristles.
+
+      d. No facial carina between the antennæ. RHYNCHOMYIINÆ
+
+        e. Arista short-plumose. _R. speciosa._ Europe. _Rhynchomyia_ R.
+            D.
+
+        ee. Arista long-plumose. _I. phasina_. Europe and Egypt.
+            _Idiopsis_. B. B.
+
+      dd. With flattened carina, the bases of the antennæ separated; no
+          abdominal macrochætæ. COSMININÆ _C. fuscipennis_. South
+          Africa. _Cosmina_
+
+    cc. Antennal arista pectinate; bases of the antennæ separated by a
+        flattened carina. RHINIINÆ R. D.
+
+      d. Cell R_5 open, or closed at the margin.
+
+        e. Third segment of the antenna twice as long as the second;
+            claws of both sexes short; cell R_5 open. _I. lunata._
+            Eastern Hemisphere. _Idia_ Meigen
+
+        ee. Third segment of the antenna three times as long as the
+            second; cell R_5 open or closed; claws of the male long and
+            slender, of the female shorter than the last tarsal joint.
+            _I. mandarina_, China. _Idiella_ B. B.
+
+      dd. Cell R_5 petiolate. _Rhinia_; and _Beccarimyia_ Rdi.
+
+  bb. Proboscis long, directed forward, adapted for piercing. STOMOXINÆ
+
+    c. Arista flat, pectinate above with plumose rays; sternopleurals
+        1:2; bases of the veins R_1 and R_{4+5} without setæ; base of
+        the media bowed down; apical cell opens before the apex of the
+        wing. African species. GLOSSINA Wied.
+
+      d. Species measuring over twelve mm. in length. _G. longipennis_
+          and FUSCA.
+
+      dd. Species less than twelve mm. in length.
+
+        e. All segments of the hind tarsi black.
+
+          f. The fourth and fifth segments of the fore tarsi black;
+              antennæ black (fig. 164). G. PALPALIS R. D.
+
+          ff. Otherwise marked. _G. bocagei_, _tachinoides_, _pallicera_.
+
+        ee. First three segments of the hind tarsi are yellow, the
+            fourth and fifth segments are black.
+
+          f. Fourth and fifth segments of the first and second pair of
+              tarsi are black.
+
+            g. The yellow bands of the abdominal segments occupy a third
+                of the segment (fig. 165). G. MORSITANS Westw.
+
+            gg. The yellow band on each segment of the abdomen occupies
+                a sixth of the segment. G. LONGIPALPIS Wied.
+
+          ff. Tarsi of the first and second pairs of legs wholly yellow.
+              _G. pallidipes_ Austen
+
+    cc. Rays of the arista not plumose; only one or two sternopleurals;
+        base of the media not strongly bowed down; apical cell opens at
+        or very near the apex of the wing.
+
+      d. Vein R_{4+5} without setæ at the base; palpi about as long as
+          the proboscis.
+
+        e. Arista pectinate (i.e. rays on one side only), the rays often
+            undulate; two yellow sternopleurals often difficult to
+            detect; vein M_{1+2} only slightly bent, the apical cell
+            hence wide open. The horn fly, H. IRRITANS (= _Lyperosia
+            serrata_) and related species. Widely distributed (figs.
+            167, 168). HÆMATOBIA R. D. not B. B.
+
+[Illustration: 165. Glossina morsitans. (×4.) After Austen.]
+
+        ee. Arista also with rays below; vein M_{1+2} more strongly
+            bent, the apical cell hence less widely open.
+
+          f. Palpi strongly spatulate at the tips, lower rays of the
+              arista about six in number, B. SANGUINOLENTUS. South Asia.
+              BDELLOLARYNX Austen
+
+          ff. Palpi feebly spatulate; apical cell of the wing narrowly
+              open slightly before the tip; sternopleurals black,
+              anterior bristle sometimes absent. H. ATRIPALPIS. Europe.
+              HÆMATOBOSCA Bezzi
+
+      dd. Vein R_{4+5} with setæ at the base.[L]
+
+        e. Veins R_1 and R_{4+5} with setæ at the base; two equally
+            prominent sternopleural macrochætæ; arista with rays both
+            above and below; palpi as long as the proboscis; apical cell
+            of the wing wide open. L. TIBIALIS. (_Hæmatobia_ B. B. not
+            R. D.). LYPEROSIOPS Town.
+
+        ee. Only vein R_{4+5} with basal setæ; anterior sternopleural
+            macrochæta wanting; arista pectinate.
+
+          f. Palpi as long as the proboscis, the latter stout, with
+              fleshy terminal labellæ; apical cell narrowly open;
+              sternopleural macrochætæ black. S. MACULOSA from Africa
+              and related species from Asia. STYGEROMYIA Austen
+
+          ff. Palpi much shorter than the proboscis, the latter pointed
+              at the apex, without fleshy labellæ; apical cell of the
+              wing wide open. S. CALCITRANS, the stable fly and related
+              species. Widely distributed in both hemispheres (fig.
+              110). STOMOXYS Geof.
+
+aa. Proboscis neither slender nor elongate, the labellæ fleshy and not
+    adapted for piercing.
+
+  b. Hypopleuræ without a vertical row of macrochætæ. MUSCINÆ
+
+    c. Arista bare; distal portion of M_{1+2} broadly curved at the end;
+        hypopleuræ with a sparse cluster of fine hairs. _S.
+        braziliana_, Southern States and southward. _Synthesiomyia_ B.
+        B.
+
+    cc. Arista pectinate or plumose.
+
+      d. Arista pectinate. _H. vittigera_, with the posterior half of
+          the abdomen metallic blue. Mexico. _Hemichlora_ V. d. W.
+
+      dd. Arista plumose.
+
+        e. Middle tibia with one or more prominent setæ on the inner
+            (flexor) surface beyond the middle, or inner surface very
+            hairy.
+
+          f. R_1 ends distad of the m-cu crossvein; M_{1+2} with a broad
+              curve near its apical end. (= _Neomesembrina_ Schnabl. =
+              _Metamesembrina_ Town). _M. meridiana._ Europe.
+              _Mesembrina_ Meigen
+
+          ff. R_1 ends proximad of the m-cu crossvein.
+
+            g. Eyes pilose, sometimes sparsely in the female.
+
+              h. Female with two or three stout orbital setæ; the hind
+                  metatarsus of the male thickened below at the base and
+                  penicillate. _D. pratorum._ Europe. _Dasyphora_ R.
+                  D.[M]
+
+              hh. Neither sex with orbital setæ.
+
+                i. Abdomen without macrochætæ; arista plumose. _C.
+                    asiatica._ Eastern Hemisphere. _Cryptolucilia_ B. B.
+
+                ii. Abdomen with strong macrochætæ; arista very
+                    short-plumose, nearly bare. _B. tachinina._ Brazil.
+                    _Reinwardtia_ B. B.
+
+            gg. Eyes bare.
+
+              h. Body densely pilose; thoracic macrochætæ wanting;
+                  middle tibiæ much elongate and bent; last section of
+                  M_{1+2} with a gentle curve. H. (_Mesembrina_)
+                  _mystacea, et al._, Europe and _H. solitaria_, N.
+                  America. _Hypodermodes_ Town.
+
+              hh. Body not densely pilose.
+
+                i. Dorsocentrals six; last section of M_{1+2} with a
+                    gentle curve.
+
+                  j. Inner dorsocentrals ("acrostichals") wanting;
+                      sternopleurals arranged 1:3. _P. cyanicolor_,
+                      _cadaverina_, etc. Europe and America _Pyrellia_
+                      R. D.
+
+                  jj. Inner dorsocentrals ("acrostichals") present;
+                      sternopleurals arranged 1:2. E. _latreillii._
+                      North America. _Eumesembrina_ Town.
+
+                ii. Dorsocentrals five; inner dorsocentrals present;
+                    last section of M_{1+2} with a rounded angle;
+                    sternopleurals arranged 1:2. _P. cornicina_ Europe
+                    and America. (_Pseudopyrellia_ Girsch.) _Orthellia_
+                    R. D.
+
+        ee. Middle tibia without a prominent bristle on the inner
+            surface beyond the middle.
+
+[Illustration: 166. Pycnosoma marginale. (×4.) After Graham-Smith.]
+
+          f. Squamula thoracalis broadened mesad and caudad as far as
+              the scutellum.
+
+            g. Sternopleural macrochætæ arranged in an equilateral
+                triangle; front of both sexes broad; genæ bare;
+                dorsocentrals six, small; wing not rilled. (To
+                COENOSINÆ). _Atherigona_ Rdi.
+
+            gg. Sternopleural macrochætæ when three are present,
+                arranged in a right triangle.
+
+              h. Last section of M_{1+2} with a more or less rounded
+                  angle (fig. 163l).
+
+                i. Eyes of the male pilose or pubescent, of the female
+                    nearly bare; m-cu crossvein usually at or proximad
+                    of the mid-distance between the r-m crossvein and
+                    the bend of M_{1+2}. P. (= _Placomyia_ R. D.)
+                    _vitripennis_. _Plaxemyia_ R. D.
+
+                ii. Eyes bare; the m-cu crossvein always nearer to the
+                    bend of M_{1+2} than to the r-m crossvein.
+
+                  j. Apex of the proboscis when extended reveals a
+                      circlet of stout chitinous teeth. P. INSIGNIS
+                      Austen, of India, bites both man and animals. (=
+                      _Pristirhynchomyia_.) PHILÆMATOMYIA Austen
+
+                  jj. Apex of the proboscis without black teeth.
+
+                    k. Eyes of male separated by a distance equal to a
+                        fourth the width of the head. House or typhoid
+                        fly. M. DOMESTICA L. Widely distributed. MUSCA
+                        L.
+
+                    kk. Eyes of the male contiguous. E. CORVINA. Europe.
+                        EUMUSCA Town
+
+              hh. Last section of M_{1+2} with a gentle curve (fig.
+                  102).
+
+                i. Eyes pilose.
+
+                  j. Claws in the male somewhat elongated; no orbitals
+                      in either sex; antennæ separated at the base by a
+                      flat carina; abdomen marked with red or yellow.
+                      _G. maculata._ Europe and America. _Graphomyia_ R.
+                      D.
+
+                  jj. Claws short and equal in the two sexes; two or
+                      three stout orbital macrochætæ in the female; R_1
+                      scarcely produced beyond the r-m crossvein; eyes
+                      contiguous in the male. _P. obsoleta._ Brazil.
+                      _Phasiophana_ Br.
+
+                ii. Eyes bare; fronto-orbital macrochætæ in a double
+                    row, antennæ contiguous at the base.
+
+                  j. One or more pairs of well developed anterior inner
+                      dorsocentral (acrostichal) macrochætæ; seta on
+                      extensor surface of hind tibia. M. ASSIMILIS,
+                      STABULANS, etc. Europe and America. MUSCINA R. D.
+
+                  jj. Anterior inner dorsocentrals and the setæ; on the
+                      extensor surface of the hind tibia wanting. _M.
+                      micans_, etc. Europe and North America. _Morellia_
+                      R. D.
+
+          ff. Squamula thoracalis not broadened mesad and caudad, not
+              reaching the margin of the scutellum; macrochætæ on
+              extensor surface of the hind tibia wanting.
+
+            g. Eyes pubescent. _M. meditabunda._ Europe and America.
+                _Myiospila_ Rdi.
+
+            gg. Eyes bare; R_1 ends before the middle of the wing. A
+                number of species from the tropics of both hemispheres.
+                _Clinopera_ V. d. W.
+
+  bb. Hypopleuræ with a vertical row of macrochætæ.
+
+    c. Eyes pubescent.
+
+      d. R_1 ends about opposite the r-m crossvein; basal section of
+          R_{4+5} bristly nearly to the crossvein; _S. enigmatica_.
+          Africa. _Somalia_ Hough
+
+      dd. R_1 ends distad of the r-m crossvein.
+
+        e. Eastern hemisphere. Australasia. _N. ochracea_, _dasypthalma_.
+            _Neocalliphora_ Br.
+
+        ee. Western Hemisphere. _T. muscinum._ Mexico. _Tyreomma_ V. d.
+            W.
+
+    cc. Eyes bare.
+
+      d. The vibrissal angle situated at a noticeable distance above the
+          level of the margin of the mouth.
+
+        e. Sternopleural macrochætæ arranged in the order 1:1.
+
+          f. Genæ with microchætæ.
+
+            g. Body grayish, with depressed yellow woolly hair among the
+                macrochætæ; wings folded longitudinally over the body
+                when at rest. Cluster flies. _P. rudis_ and related
+                species, widely distributed. _Pollenia_ R. D.[N]
+
+            gg. Body metallic blue or green. Eastern Hemisphere.
+
+              h. Vibrissal angle placed very high above the oral margin;
+                  a carina between the antennæ; outer posthumeral
+                  wanting; anterior intraalar present. _T. viridaurea_.
+                  Java. _Thelychæta_ Br.
+
+[Illustration: 167. Horn fly. (_a_) egg; (_b_) larva; (_c_) puparium;
+(_d_) adult. (×4). Bureau of Entomology]
+
+              hh. Vibrissal angle moderately high above the oral margin;
+                  carina small or wanting; no post humeral macrochæta;
+                  lower squamæ hairy above. (= _Paracompsomyia_ Hough)
+                  (fig. 166). _Pycnosoma_ Br.
+
+          ff. Genæ bare. _S. terminata_. Eastern Hemisphere
+              _Strongyloneura_ Bigot
+
+        ee. Sternopleurals arranged 2:1.
+
+          f. Body metallic green or blue, with gray stripes; genæ hairy
+              to the lower margin; post humerals often wanting; lower
+              squamæ bare above. (= _Compsomyia_ Rdi.). CHRYSOMYIA R. D.
+
+            g. With one or two orbitals; height of bucca less than half
+                the height of the eye. South and east U. S. (fig. 107).
+                C. MARCELLARIA
+
+            gg. No orbitals; height of bucca about a third less than
+                height of eye. West U. S. _C. wheeleri_ Hough
+
+          ff. Body black or sordidly metallic greenish gray, usually
+              yellow pollinose or variegate; genæ at most hairy above.
+              _N. stygia_. Eastern Hemisphere. _Neopollenia_ Br.
+
+      dd. Vibrissal angle situated nearly on a level of the oral margin.
+
+        e. Species wholly blackish, bluish, or greenish metallic in
+            color.
+
+          f. First section of R_{4+5} with at most three or four small
+              bristles at the immediate base.
+
+            g. The bend of M_{1+2} a gentle curve; costal spine present;
+                cell R_5 closed, ending before the apex of the wing. _S.
+                cuprina._ Java. _Synamphoneura_ Bigot
+
+            gg. Bend of M_{1+2} angular; or the insect differs in other
+                characters; dorsal surface of the squamula thoracalis
+                hairy (except in _Melinda_); arista plumose only on the
+                basal two-thirds (except usually in _Calliphora_ and
+                _Eucalliphora_).
+
+[Illustration: 168. Head of horn-fly (Lyperosia irritans); (_a_) female;
+(_b_) male; (_c_) lateral aspect of female. Bureau of Entomology.]
+
+              h. Arista plumose only on the basal two-thirds.
+
+                i. Base of the antennæ ventrad of the middle of the eye;
+                    eyes of the male nearly contiguous; genæ hairy;
+                    second abdominal segment with median marginal
+                    macrochætæ; two, rarely three, postsutural intraalar
+                    macrochætæ.
+
+                  j. Squamula thoracalis dorsally with long black hairs;
+                      male hypopygium two-segmented, large, projecting;
+                      claws and pulvilli of the male elongate; three
+                      strong sternopleural macrochætæ; genæ at least
+                      half the width of the eye; buccæ (cheeks) half the
+                      height of the eyes; oviviparous. _O. sepulcralis._
+                      Europe. _Onesia_ R. D.
+
+                  jj. Dorsal surface of the squamula thoracalis bare;
+                      male hypopygium small, scarcely projecting below;
+                      claws and pulvilli not elongate; two stout
+                      sternopleural macrochætæ, sometimes with a
+                      delicate one below the anterior; genæ nearly
+                      linear in the male; buccæ about a third of the eye
+                      height; oviparous. _M. cærulea_. Europe.
+                      _Melinda_. R. D.
+
+[Illustration: 169. Lateral and dorsal aspects of the thorax, and
+frontal aspect of the head of a muscoidean fly, with designations of the
+parts commonly used in taxonomic work.]
+
+                ii. Base of the antennæ dorsad of the middle of the eye;
+                    eyes of both sexes distinctly separated; dorsal
+                    surface of the squamula thoracalis with black hairs;
+                    two postsutural intraalar macrochætæ.
+
+                  j. Hypopygium of the male large, with a pair of
+                      slightly curved forceps whose ends are concealed
+                      in a longitudinal slit in the fifth ventral
+                      sclerite; third posterior inner dorso-central
+                      (acrostichal) macrochætæ absent; anterior
+                      intraalar rarely present; abdomen usually not
+                      pollinose; the second segment without median
+                      marginal macrochætæ; face yellow. _C. mortuorum_,
+                      _cadaverina_, and related species. Both
+                      hemispheres. _Cynomyia_ R. D.[O]
+
+[Illustration: 170. Sepsis violacea; puparium and adult. (See page 297.)
+After Howard.]
+
+                  jj. Three pairs of posterior inner dorsocentrals
+                      (acrostichals) present; second abdominal segment
+                      with a row of marginal macrochætæ; genæ hairy, at
+                      least above.
+
+                    k. Hypopygium of the male with a projecting style.
+                        _S. stylifera_. Europe. _Steringomyia_ Pok.
+
+
+                    kk. Hypopygium of the male without style. _A.
+                        stelviana_ B. B. _Acrophaga_ B. B.
+
+              hh. Arista usually plumose nearly to the tip; posterior
+                  dorsocentrals and inner dorsocentrals (acrostichals)
+                  well developed; dorsal surface of the squamula
+                  thoracalis hairy; abdomen metallic and usually
+                  pollinose; genæ hairy.
+
+                i. With one pair of ocellar macrochætæ. C. VOMITORIA,
+                    ERYTHROCEPHALA, VIRIDESCENS, and related species.
+                    Both hemispheres. CALLIPHORA R. D.
+
+                ii. With two strong pairs of ocellar macrochætæ. _E.
+                    latifrons._ Pacific slope of the U. S.
+                    _Eucalliphora_ Town.
+
+          ff. First section of R_{4+5} bristly near or quite half way to
+              the small crossvein; dorsal surface of the squamula
+              thoracalis is bare; the hypopygium of the male is
+              inconspicuous.
+
+            g. Genæ bare; posterior inner and outer dorsocentrals
+                distinct and well developed. _L. cæsar_, _sericata_,
+                _sylvarum_, and related species. Widely distributed in
+                both hemispheres (fig. 103). LUCILIA R. D.
+
+            gg. Genæ with microchætæ, at least down to the level of the
+                base of the arista.
+
+              h. Mesonotum flattened behind the transverse suture.
+
+                i. Posterior dorsocentrals inconstant and unequally
+                    developed; one pair of posterior inner
+                    dorsocentrals. _P. terrænovæ._ North America.
+                    _Protophormia_ Town.
+
+                ii. Posterior dorsocentrals well developed, the inner
+                    dorsocentrals (acrostichals) unequally developed.
+                    _P. azurea_, _chrysorrhœa_, etc. Europe and America.
+                    _Protocalliphora_ Hough
+
+              hh. Mesonotum not flattened behind the transverse suture;
+                  posterior inner and outer dorsocentrals inconstant and
+                  unequally developed. _P. regina._ Europe and America.
+                  _Phormia_ R. D.
+
+        ee. Species more or less rufous or yellow in color.
+
+          f. Anterior dorsocentrals wanting; first section of the
+              R_{4+5} at most only bristly at the base, bend near apex
+              of M_{1+2} rectangular, R_1 ends over the crossvein;
+              fronto-orbital macrochæta absent; eyes of the male
+              contiguous. _C. semiviridis._ Mexico. _Chloroprocta_
+              V. d. W
+
+          ff. With another combination of characters.
+
+            g. Body robust, of large size, abdomen elongate, not round;
+                genæ with several ranges of microchætæ; vibrissal ridges
+                strongly convergent; abdomen with well developed
+                macrochætæ; costal spine usually absent; eyes of the
+                male widely separated.
+
+[Illustration: 171. Stigmata of the larvæ of Muscoidea. Third instar.
+(_a_) Cynomyia cadaverina; (_b_) Phormia regina; (_c_) Chrysomyia
+macellaria; (_d_) Musca domestica; (_e_) Sarcophaga sp.; (_f_) Oestris
+ovis; (_g_) Gastrophilus equi; (_h_) Sarcophaga sp.; (_i_) Pegomyia
+vicina; (_j_) Protocalliphora azurea; (_k_) Hypoderma lineata; (_l_)
+Muscina stabulans. Magnification for f, g, and k, ×25; all others, ×
+50.]
+
+              h. Peristome broad, pteropleural macrochætæ distinct; one
+                  or two sternopleurals; in the female a single orbital
+                  macrochæta; last abdominal segment without discal
+                  macrochætæ; hypopygial processes of the male with a
+                  long stylet; second abdominal segment of the female
+                  sometimes much elongate. A. LUTEOLA (fig. 86).
+                  Africa. The sub-genus _Chœromyia_ Roub. is included
+                  here. AUCHMEROMYIA B. B.
+
+              hh. Peristome narrow; no pteropleurals, two
+                  sternopleurals; two orbitals in the female; second
+                  segment not elongate; the fourth with two well
+                  developed discal macrochætæ. B. DEPRESSA. Africa.
+                  BENGALIA R. D
+
+            gg. With another combination of characters.
+
+              h. Costal spine present; body in part black; antennæ
+                  noticeably shorter than the epistome, inserted above
+                  the middle of the eye and separated from each other by
+                  a carina; abdominal segments with marginal macrochætæ;
+                  sternopleurals 2:1 or 1:1. _Paratricyclea_ Villen.
+
+              hh. Costal spine not distinct, or if present, insect
+                  otherwise different.
+
+                i. Genæ with several ranges of microchætæ; vibrissal
+                    ridges strongly converging; peristome broad; arista
+                    moderately plumose; sternopleurals usually 1:1;
+                    color entirely testaceous. C. ANTHROPOPHAGA (fig.
+                    87) and GRUNBERGI. Africa. CORDYLOBIA Grünb.
+
+                ii. Genæ bare or with but one range of setæ; vibrissal
+                    ridges less converging; peristome narrow; arista
+                    long plumose.
+
+                  j. Genæ with a single row of microchætæ.
+
+                    k. Sternopleurals 2:1; color entirely testaceous.
+                        _Ochromyia_ Macq.[P]
+
+                    kk. Sternopleurals 1:1. _P. varia_ Hough. Africa.
+                        _Parochromyia_ Hough
+
+                  jj. Genæ bare.
+
+                    k. Basal section of R_{4+5} bristly only at the
+                        immediate base, distally M_{1+2} with a broad
+                        curve; distal portion of the abdomen metallic;
+                        sternopleurals usually 1:1, rarely 2:1. _M.
+                        æneiventris_ Wd. Tropic America.
+                        _Mesembrinella._ G. T.
+
+                    kk. R_{4+5} bristly at least nearly half way to the
+                        small crossvein; sternopleurals 1:1.
+
+                      l. Macrochætæ of the abdomen marginal; neither sex
+                          with orbitals; no carina between the base of
+                          the antennæ; three pairs of presutural inner
+                          dorsocentrals. Eastern hemisphere. _T.
+                          ferruginea._ _Tricyclea V. d. W_. (=
+                          _Zonochroa_ B. B. according to Villeneuve
+                          1914).
+
+                      ll. Abdomen without macrochætæ; wing usually with
+                          a marginal streak and gray markings. Brazil.
+                          Hemilucilia B. B.
+
+[Illustration: 172. Left hand stigmata of the larvæ of muscoidea. Third
+instar. (_a_) Lucilia cæsar; (_b_) Calliphora vomitoria; (_c_) Stomoxys
+calcitrans; (_d_) Orthellia cornicina; (_e_) Pyrellia cadaverina;
+(_f_) Hæmatobia irritans; (_g_) Mesembrina mystacea; (_h_) Mesembrina
+meridiana; (_i_) Myospila meditabunda; (_j_) Mydæa urbana; (_k_)
+Polietes albolineata; (_l_) Polietes lardaria; (_m_) Morellia hortorum;
+(_n_) Hydrotæa dentipes; (_o_) Hebecnema umbratica; (_p_) H. vespertina;
+(_q_) Limnophora septemnotata; (_r_) Muscina stabulans. (_a_ and _b_)
+after MacGregor; (_d_) after Banks; all others after Portchinsky.
+Magnification varies. The relative distance to the median line is
+indicated in each figure.]
+
+
+SIPHONAPTERA. Fleas
+
+Adapted from a table published by Oudemans.
+
+a. Elongated fleas, with jointed (articulated) head, with combs
+    (ctenidia) on head and thorax; with long, oval, free-jointed
+    flagellum of the antenna (fig. 92d). Suborder FRACTICIPATA
+
+  b. With ctenidia in front of the antennæ and on the genæ (cheeks);
+      maxillæ with acute apices; labial palpi five-segmented,
+      symmetrical; eyes poorly developed or wanting. On rodents.
+      HYSTRICHOPSYLLIDÆ
+
+    c. Abdominal segments without ctenidia.
+
+      d. Post-tibial spines in pairs and not in a very close set row;
+          head with ctenidia. _Ctenophthalmus_ Kol.
+
+      dd. Post-tibial spines mostly single and in a close set row.
+          _Ctenopsyllus_ and _Leptopsyllus_. The last genus has recently
+          been erected for _L. musculi_, a widely distributed species
+          occurring on rats and mice.
+
+    cc. Abdominal segments with one or more ctenidia; post-tibial spines
+        in numerous, short, close-set transverse rows on posterior
+        border with about four spines in each row. _H. americana._
+        _Hystrichopsylla_ Taschenb.
+
+  bb. With only two pairs of subfrontal ctenidia; labial palpi
+      five-segmented, symmetrical; eyes vestigial or wanting. On bats.
+      (= ISCHNOPSYLLIDÆ). NYCTERIDIPSYLLIDÆ
+
+    With more or less blunt maxilla; all tibiæ with notch; a single
+        antepygidial bristle; metepimeron without ctenidium. _N.
+        crosbyi_ from Missouri was found on bats. Rothschild suggests
+        that this is probably the same as _N. insignis_. (=
+        _Ischnopsyllus_ = _Ceratopsyllus_), _Nycteridiphilus_
+
+aa. Head not jointed, i.e. the segments coalescent, traces of the
+    segmentation still being visible in the presence of the vertex
+    tubercle, the falx (sickle-shaped process), and a suture. Suborder
+    INTEGRICIPITA
+
+  b. Flagellum of the antennæ long and oval.
+
+    c. Usually elongate fleas, with a free-segmented flagellum of the
+        antenna; thorax not shorter than the head, longer than the first
+        tergite.
+
+      d. Genæ of the head and the pronotum with ctenidia. NEOPSYLLIDÆ
+
+        e. Labial palpi four or five-segmented; symmetrical; hind coxæ
+            with patch of spines inside; row of six spatulate spines on
+            each side in front of the antennæ. _C. ornate_ found on a
+            California mole. _Corypsylla_
+
+        ee. Labial palpi two-segmented, transparent, membranous. On
+            hares. _Spilopsyllus_ Baker
+
+      dd. No ctenidium on the head.
+
+        e. Pronotum with ctenidium. DOLICHOPSYLLIDÆ
+
+          f. Labial palpi five-segmented, symmetrical.
+
+            g. Antepygidial bristles one to three; eyes present.
+
+              h. Inner side of hind coxæ distally with a comb of minute
+                  teeth; falx present. On rodents and carnivores.
+                  _Odontopsyllus_ Baker
+
+              hh. Inner side of hind coxæ without comb or teeth. Many
+                  North American species on rodents. CERATOPHYLLUS
+                  Curtis
+
+            gg. Antepygidial bristles five on each side; eyes absent;
+                suture white. _D. stylosus_ on rodents. _Dolichopsyllus_
+                Baker
+
+          ff. Labial palpi four or five-segmented; asymmetrical
+              (membranous behind), apex acute. _Hoplopsyllus anomalus_
+              found on Spermophiles in Colorado. HOPLOPSYLLIDÆ
+
+        ee. Pronotum without ctenidium. _Anomiopsyllus californicus_ and
+            _nudatus_ on rodents. ANOMIOPSYLLIDÆ
+
+    cc. Very short fleas; flagellum of the antenna with pseudo-segments
+        coalescent; thorax much shorter than the head and than the first
+        tergite. HECTOPSYLLIDÆ
+
+      Flagellum of the antenna with six coalescent pseudo-segments;
+          maxilla blunt. The chigger on man (fig. 93). D. PENETRANS. (=
+          RHYNCHOPRION = SARCOPSYLLA) DERMATOPHILUS Guérin
+
+  bb. Flagellum short, round, free portion of the first segment shaped
+      like a mandolin.
+
+    c. Thorax not shorter than the head, longer than the first tergite;
+        flagellum either with free segments or in part with the segments
+        coalescent.
+
+      d. Head and pronotum with ctenidium; labial palpi asymmetrical.
+          ARCHÆOPSYLLIDÆ
+
+        With four subfrontal, four genal, and one angular ctenidia.
+            Widely distributed. CTENOCEPHALUS Kol.
+
+        e. Head rounded in front (fig. 92a). Dog flea. C. CANIS
+
+        ee. Head long and flat (fig. 92b). Cat flea. C. FELIS
+
+      dd. Neither head nor pronotum with ctenidium. Labial palpi
+          asymmetrical, membranous behind. PULICIDÆ
+
+        e. Mesosternite narrow, without internal rod-like thickening
+            from the insertion of the coxæ upwards. Human flea, etc.
+            PULEX L.
+
+        ee. Mesosternite broad with a rod-like internal thickening from
+            the insertion of the coxæ upwards (fig. 89). X.
+            (LÅ’MOPSYLLA) CHEOPIS, plague or rat flea. XENOPSYLLA
+
+    cc. Thorax much shorter than the head and than the first tergite.
+        ECHIDNOPHAGIDÆ. E. GALLINACEA, the hen flea also attacks man
+        (fig. 96). (= ARGOPSYLLA = XESTOPSYLLA) ECHIDNOPHAGA Olliff.
+
+
+FOOTNOTES:
+
+[E] Adapted from Banks, Nuttall, Warburton, Stiles, _et al._
+
+[F] Dr. C. W. Stiles considers the species which is responsible for
+spotted fever distinct from the _venustus_ of Banks, separating it as
+follows:
+
+Goblet cells about 75 in the male or 105 in the female. Texas. _D.
+venustus._
+
+Goblet cells 157 in the male, or 120 in the female; stigmal plate shaped
+as shown in the figure (figs. 150 a, b). Montana, etc. D. ANDERSONI.
+
+[G] Professor C. R. Crosby who has been working upon certain capsids
+states that he and his assistant have been bitten by LYGUS PRATENSIS,
+the tarnished plant bug, by CHLAMYDATUS ASSOCIATUS and by ORTHOTYLUS
+FLAVOSPARSUS, though without serious results.
+
+[H] Species marked with an * are known to transmit malaria. Species
+found only in tropical North America and not known to carry malaria have
+been omitted from this table, but all found in the United States are
+included.
+
+[I] This table to the North American genera of the Tabanidæ is adapted
+from one given by Miss Ricardo.
+
+[J] The classification of the Muscoidea as set forth by Schiner and
+other earlier writers has long been followed, although it is not
+satisfactory, being admittedly more or less artificial. Within the last
+two or three decades several schemes have been advanced, that of Brauer
+and Bergenstamm and of Girschner, with the modifications of Schnabl and
+Dziedzicki having obtained most favor in Europe. Townsend, in 1908,
+proposed a system which differs from Girschner's in some respects, but
+unfortunately it has not yet been published in sufficient detail to
+permit us to adopt it. From considerations of expediency we use here the
+arrangement given in Aldrich's Catalogue of North American Diptera,
+though we have drawn very freely upon Girschner's most excellent paper
+for taxonomic characters to separate the various groups.
+
+It may sometimes be found that a species does not agree in all the
+characters with the synopsis; in this case it must be placed in the
+group with which it has the most characters in common.
+
+[K] There are several genera of flies of the family _Cordyluridæ_; (i.e.
+_Acalyptratæ_) which might be placed with the _Anthomyiidæ_ (i.e.
+_Calyptratæ_), owing to the relatively large size of their squamæ. As
+there is no single character which will satisfactorily separate all
+doubtful genera of these two groups we must arbitrarily fix the limits.
+In general those forms on the border line having a costal spine, or
+lower squama larger than the upper, or the lower surface of the
+scutellum more or less pubescent, or the eyes of the male nearly or
+quite contiguous, or the eyes hairy, or the frontal setæ decussate in
+the female; or any combination of these characters may at once be placed
+with the _Anthomyiidæ_. Those forms which lack these characteristics and
+have at least six abdominal segments (the first and second segments
+usually being more or less coalescent) are placed with the Acalyptrates.
+There are other acalyptrates with squamæ of moderate size which have
+either no vibrissæ, or have the subcosta either wholly lacking or
+coalescent in large part with R_1 or have spotted wings; they, therefore
+will not be confused with the calyptrates.
+
+[L] _Pachymyia_ Macq. is closely related to _Stomoxys_. It differs in
+having the arista rayed both above and below. _P. vexans_, Brazil.
+
+[M] The genus _Eudasyphora_ Town. has recently been erected to contain
+_D. lasiophthalma_.
+
+[N] _Nitellia_, usually included in this genus has the apical cell
+petiolate. _Apollenia_ Bezzi, has recently been separated from
+_Pollenia_ to contain the species _P. nudiuscula_. Both genera belong to
+the Eastern hemisphere.
+
+[O] The following three genera are not sufficiently well defined to
+place in this synopsis. In color and structural characters they are
+closely related to _Cynomyia_ from which they may be distinguished as
+follows. _Catapicephala_ Macq., represented by the species _C.
+splendens_ from Java, has the setæ on the facial ridges rising to the
+base of the antennæ and has median marginal macrochætæ on the abdominal
+segments two to four: _Blepharicnema_ Macq., represented by _B.
+splendens_ from Venezuela has bare genæ, oral setæ not ascending; tibiæ
+villose; claws short in both sexes; _Sarconesia_ Bigot with the species
+_S. chlorogaster_ from Chile, setose genæ; legs slender, not villose;
+claws of the male elongate.
+
+[P] _Plinthomyia_ Rdi. and _Hemigymnochæta_ Corti are related to
+_Ochromyia_, though too briefly described to place in the key.
+
+
+
+
+APPENDIX
+
+HYDROCYANIC ACID GAS AGAINST HOUSEHOLD INSECTS
+
+
+The following directions for fumigating with hydrocyanic acid
+gas are taken from Professor Herrick's circular published by the
+Cornell Reading Course:
+
+Hydrocyanic acid gas has been used successfully against household
+insects and will probably be used more and more in the future.
+It is particularly effective against bed-bugs, and cockroaches, but
+because _it is such a deadly poison it must be used very carefully_.
+
+The gas is generated from the salt potassium cyanid, by treating
+it with sulfuric acid diluted with water. Potassium cyanid is a
+most poisonous substance and the gas emanating from it is also
+deadly to most, if not all, forms of animal life. The greatest care
+must always be exercised in fumigating houses or rooms in buildings
+that are occupied. Before fumigation a house should be vacated.
+It is not necessary to move furniture or belongings except brass or
+nickel objects, which may be somewhat tarnished, and butter, milk,
+and other larder supplies that are likely to absorb gas. If the nickel
+and brass fixtures or objects are carefully covered with blankets
+they will usually be sufficiently protected.
+
+There may be danger in fumigating one house in a solid row of
+houses if there is a crack in the walls through which the gas may find
+its way. It also follows that the fumigation of one room in a house
+may endanger the occupants of an adjoining room if the walls between
+the two rooms are not perfectly tight. It is necessary to keep
+all these points in mind and to do the work deliberately and thoughtfully.
+The writer has fumigated a large college dormitory of 253
+rooms, once a year for several years, without the slightest accident
+of any kind. In order to fumigate this building about 340 pounds
+of cyanid and the same amount of sulfuric acid were used each time.
+In addition to this, the writer has fumigated single rooms and smaller
+houses with the gas. In one instance the generating jars were too
+small; the liquid boiled over and injured the floors and the rugs.
+Such an accident should be avoided by the use of large jars and by
+placing old rugs or a quantity of newspapers beneath the jars.
+
+
+THE PROPORTIONS OF INGREDIENTS
+
+Experiments and experience have shown that the potassium
+cyanid should be ninety-eight per cent pure in order to give satisfactory
+results. The purchaser should insist on the cyanid being of
+at least that purity, and it should be procurable at not more than
+forty cents per pound. The crude form of sulfuric acid may be used.
+It is a thickish, brown liquid and should not cost more than four or
+five cents a pound. If a room is made tight, one ounce of cyanid for
+every one hundred cubic feet of space has been shown to be sufficient.
+It is combined with the acid and water in the following proportions:
+
+  Potassium cyanid                       1 ounce
+  Commercial sulfuric acid               1 fluid ounce
+  Water                                  3 fluid ounces
+
+
+A SINGLE ROOM AS AN EXAMPLE
+
+Suppose a room to be 12 by 15 by 8 feet. It will contain 12 × 15 × 8, or
+1440 cubic feet. For convenience the writer always works on the basis of
+complete hundreds; in this case he would work on the basis of 1500 cubic
+feet, and thus be sure to have enough. The foregoing room, then, would
+require 15 ounces of cyanid, 15 ounces of sulfuric acid, and 45 ounces
+of water. The room should be made as tight as possible by stopping all
+the larger openings, such as fireplaces and chimney flues, with old rags
+or blankets. Cracks about windows or in other places should be sealed
+with narrow strips of newspaper well soaked in water. Strips of
+newspaper two or three inches wide that have been thoroughly soaked in
+water may be applied quickly and effectively over the cracks around the
+window sash and elsewhere. Such strips will stick closely for several
+hours and may be easily removed at the conclusion of the work.
+
+While the room is being made tight, the ingredients should be measured
+according to the formula already given. The water should be measured and
+_poured first_ into a stone jar for holding at least two gallons. The
+jar should be placed in the middle of the room, with an old rug or
+several newspapers under it in order to protect the floor.
+
+The required amount of sulfuric acid should then be poured rather slowly
+into the water. _This process must never be reversed; that is, the acid
+must never be poured into the jar first._ The cyanid should be weighed
+and put into a paper bag beside the jar. All hats, coats, or other
+articles that will be needed before the work is over should be removed
+from the room. When everything is ready the operator should drop the bag
+of cyanid gently into the jar, holding his breath, and should walk
+quickly out of the room. The steam-like gas does not rise immediately
+under these conditions, and ample time is given for the operator to walk
+out and shut the door. If preferred, however, the paper bag may be
+suspended by a string passing through a screw eye in the ceiling and
+then through the keyhole of the door. In this case the bag may be
+lowered from the outside after the operator has left the room and closed
+the door.
+
+The writer has most often started the fumigation toward evening and left
+it going all night, opening the doors in the morning. The work can be
+done, however, at any time during the day and should extend over a
+period of five or six hours at least. It is said that better results
+will be obtained in a temperature of 70° F., or above, than at a lower
+degree.
+
+At the close of the operation the windows and doors may be opened from
+the outside. In the course of two or three hours the gas should be
+dissipated enough to allow a person to enter the room without danger.
+The odor of the gas is like that of peach kernels and is easily
+recognized. The room should not be occupied until the odor has
+disappeared.
+
+
+FUMIGATING A LARGE HOUSE
+
+The fumigation of a large house is merely a repetition, in each room and
+hall, of the operations already described for a single room. All the
+rooms should be made tight, and the proper quantities of water and
+sulfuric acid should be measured and poured into jars placed in each
+room with the cyanid in bags besides the jars. When all is ready, the
+operator should _go to the top floor and work downward_ because the gas
+is lighter than air and tends to rise.
+
+
+PRECAUTIONS
+
+The cyanid should be broken up into small pieces not larger than small
+eggs. This can best be done on a cement or brick pavement. It would be
+advantageous to wear gloves in order to protect the hands, although the
+writer has broken many pounds of cyanid without any protection on the
+hands. Wash the hands thoroughly at frequent intervals in order to
+remove the cyanid.
+
+The operations of the work must be carried out according to directions.
+
+The work should be done by a calm, thoughtful and careful person--best
+by one who has had some experience.
+
+Conspicuous notices of what has been done should be placed on the doors,
+and the doors should be locked so that no one can stray into the rooms.
+
+The gas is lighter than air, therefore one should always begin in the
+rooms at the top of the house and work down.
+
+After fumigation is over the contents of the jar should be emptied into
+the sewer or some other safe place. The jars should be washed thoroughly
+before they are used again.
+
+_It must be remembered that cyanid is a deadly poison_; but it is very
+efficient against household insects, if carefully used, and is not
+particularly dangerous when properly handled.
+
+
+LESIONS PRODUCED BY THE BITE OF THE BLACK-FLY
+
+While this text was in press there came to hand an important paper
+presenting a phase of the subject of black fly injury so different from
+others heretofore given that we deem it expedient to reproduce here the
+author's summary. The paper was published in _The Journal of Cutaneous
+Diseases_, for November and December, 1914, under the title of "A
+Clinical, Pathological and Experimental Study of the Lesions Produced by
+the Bite of the Black Fly (_Simulium venustum_)," by Dr. John Hinchman
+Stokes, of the University of Michigan.
+
+
+RESUME AND DISCUSSION OF EXPERIMENTAL FINDINGS
+
+The principal positive result of the work has been the experimental
+reproduction of the lesion produced by the black-fly in characteristic
+histological detail by the use of preserved flies. The experimental
+lesions not only reproduced the pathological pictures, but followed a
+clinical course, which in local symptomatology especially, tallied
+closely with that of the bite. This the writer interprets as
+satisfactory evidence that the lesion is not produced by any living
+infective agent. The experiments performed do not identify the nature of
+the toxic agent. Tentatively they seem to bring out, however, the
+following characteristics.
+
+1. The product of alcoholic extraction of flies do not contain the toxic
+agent.
+
+2. The toxic agent is not inactivated by alcohol.
+
+3. The toxic agent is not destroyed by drying fixed flies.
+
+4. The toxic agent is not affected by glycerin, but is, if anything,
+more active in pastes made from the ground fly and glycerin, than in the
+ground flies as such.
+
+5. The toxic agent is rendered inactive or destroyed by hydrochloric
+acid in a concentration of 0.25%.
+
+6. The toxic agent is most abundant in the region of the anatomical
+structures connected with the biting and salivary apparatus (head and
+thorax).
+
+7. The toxic agent is not affected by a 0.5% solution of sodium
+bicarbonate.
+
+8. The toxic agent is not affected by exposure to dry heat at 100° C.
+for two hours.
+
+9. The toxic agent is destroyed or rendered inactive in alkaline
+solution by a typical hydrolytic ferment, pancreatin.
+
+10. Incomplete experimental evidence suggests that the activity of the
+toxic agent may be heightened by a possible lytic action of the blood
+serum of a sensitive individual, and that the sensitive serum itself may
+contain the toxic agent in solution.
+
+These results, as far as they go (omitting No. 10), accord with Langer's
+except on the point of alcoholic solubility and the effect of acids. The
+actual nature of the toxic agent in the black-fly is left a matter of
+speculation.
+
+The following working theories have suggested themselves to the writer.
+First, the toxin may be, as Langer believes in the case of the bee, an
+alkaloidal base, toxic as such, and neutralized after injection by
+antibodies produced for the occasion by the body. In such a case the
+view that a partial local fixation of the toxin occurs, which prevents
+its immediate diffusion, is acceptable. Through chemotactic action,
+special cells capable of breaking up the toxin into harmless elements
+are attracted to the scene. Their function may be, on the other hand, to
+neutralize directly, not by lysis. This would explain the rôle of the
+eosinophiles in the black-fly lesion. If their activities be essential
+to the destruction or neutralization of the toxin, one would expect them
+to be most numerous where there was least reaction. This would be at the
+site of a bite in an immune individual. A point of special interest for
+further investigation, would be the study of such a lesion.
+
+Second, it is conceivable that the injected saliva of the fly does not
+contain an agent toxic as such. It is possible, that like many foreign
+proteins, it only becomes toxic when broken down. The completeness and
+rapidity of the breaking down depends on the number of eosinophiles
+present. In such a case immunity should again be marked by intense
+eosinophilia.
+
+[Illustration: 173. Fifth day mature lesion. Lower power drawing showing
+papillary Å“dema and infiltrate in the region of the puncture. After Dr.
+J. H. Stokes]
+
+Third, lytic agents in the blood serum may play the chief rôle in the
+liberation of the toxic agent from its non-toxic combination. An immune
+individual would then be one whose immunity was not the positive one of
+antibody formation, but the negative immunity of failure to metabolize.
+An immune lesion in such a case might be conceived as presenting no
+eosinophilia, since no toxin is liberated. If the liberation of the
+toxin is dependent upon lytic agents present in the serum rather than in
+any cellular elements, a rational explanation would be available for the
+apparent results (subject to confirmation) of the experiment with
+sensitive and immune sera. In this experiment it will be recalled that
+the sensitive serum seemed to bring out the toxicity of the ground
+flies, and the serum itself seemed even to contain some of the dissolved
+or liberated toxin. The slowness with which a lesion develops in the
+case of the black-fly bite supports the view of the initial lack of
+toxicity of the injected material. The entire absence of early
+subjective symptoms, such as pain, burning, etc., is further evidence
+for this view. It would appear as if no reaction occurred until lysis of
+an originally non-toxic substance had begun. Regarding the toxin itself
+as the chemotactic agent which attracts eosinophiles, its liberation in
+the lytic process and diffusion through the blood stream attracts the
+cells in question to the point at which it is being liberated. Arriving
+upon the scene, these cells assist in its neutralization.
+
+The last view presented is the one to which the author inclines as the
+one which most adequately explains the phenomena.
+
+A fourth view is that the initial injection of a foreign protein by the
+fly (i.e., with the first bite) sensitizes the body to that protein. Its
+subsequent injection at any point in the skin gives rise to a local
+expression of systematic sensitization. Such local sensitization
+reactions have been described by Arthus and Breton, by Hamburger and
+Pollack and by Cowie. The description of such a lesion given by the
+first named authors, in the rabbit, however, does not suggest,
+histopathologically at least, a strong resemblance to that of the
+black-fly. Such an explanation of many insect urticariæ deserves further
+investigation, however, and may align them under cutaneous expressions
+of anaphylaxis to a foreign protein injected by the insect. Depending on
+the chemical nature of the protein injected, a specific chemotactic
+reaction like eosinophilia may or may not occur. Viewed in this light
+the development of immunity to insect bites assumes a place in the
+larger problem of anaphylaxis.
+
+[Illustration: 174. Experimental lesion produced from alcohol-fixed
+flies, dried and ground into a paste with glycerin. After Dr. J. H.
+Stokes]
+
+
+SUMMARY
+
+In order to bring the results of the foregoing studies together, the
+author appends the following résumé of the clinical data presented in
+the first paper.
+
+The black-fly, _Simulium venustum_, inflicts a painless bite, with
+ecchymosis and hæmorrhage at the site of puncture. A papulo-vesicular
+lesion upon an urticarial base slowly develops, the full course of the
+lesion occupying several days to several weeks. Marked differences in
+individual reaction occur, but the typical course involves four stages.
+These are, in chronological order, the papular stage, the vesicular or
+pseudovesicular, the mature vesico-papular or weeping papular stage and
+the stage of involution terminating in a scar. The papule develops in
+from 3 to 24 hours. The early pseudovesicle develops in 24 to 48 hours.
+The mature vesico-papular lesion develops by the third to fifth day and
+may last from a few days to three weeks. Involution is marked by
+cessation of oozing, subsidence of the papule and scar-like changes at
+the site of the lesion. The symptoms accompanying this cycle consist of
+severe localized or diffused pruritus, with some heat and burning in the
+earlier stages if the Å“dema is marked. The pruritus appears with the
+pseudovesicular stage and exhibits extraordinary persistence and a
+marked tendency to periodic spontaneous exacerbation. The flies tend to
+group their bites and confluence of the developing lesions in such cases
+may result in extensive Å“dema with the formation of oozing and
+crusted plaques. A special tendency on the part of the flies to attack
+the skin about the cheeks, eyes and the neck along the hair line and
+behind the ears, is noted. In these sites inflammation and Å“dema may
+be extreme.
+
+A distinctive satellite adenopathy of the cervical glands develops in
+the majority of susceptible persons within 48 hours after being bitten
+in the typical sites. This adenopathy is marked, discrete and painful,
+the glands often exquisitely tender on pressure. It subsides without
+suppuration.
+
+Immunity may be developed to all except the earliest manifestations, by
+repeated exposures. Such an immunity in natives of an infested locality
+is usually highly developed. There are also apparently seasonal
+variations in the virulence of the fly and variations in the reaction of
+the same individual to different bites.
+
+Constitutional effects were not observed but have been reported.
+
+
+
+
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+   systematische Stellung der Anopluren, nebst Bemerkungen zur
+   Systematik der Insektenordnungen. Zool. Anz. xxviii, p. 121-147.
+
+ESTEN, W. M. and MASON, C. J. 1908. Sources of bacteria in milk. Storrs
+   Agric. Exp. Sta. Bul. li, p. 65-109.
+
+EWING, H. E. 1912. The origin and significance of parasitism in the
+   Acarina. Trans. Acad. Sci. of St. Louis. xxi, p. 1-70. pls. i-vii.
+
+EYSELL, A. 1913. Die Krankheitsereger und Krankheitsüberträger unter den
+   Arthropoden. See, Mense (1913).
+
+FELT, E. P. 1904. Mosquitoes or Culicidæ of New York State. N. Y. State
+   Museum. Bul. 79. p. 241-391. 57 plates.
+
+---- 1913. Queen Blow-fly. Georgian flesh-fly. 28th rept. of the State
+   Entomologist. p. 75-92.
+
+FINLAY, CHARLES J. 1881 et seq. Trabajos selectos. Selected papers.
+   Republica de Cuba. Secretaria de Sanidad y Beneficencia. Havana 1912.
+   xxxiv + 657 p.
+
+FORBES, S. A. 1912. On black-flies and buffalo-gnats, (_Simulium_), as
+   possible carriers of pellagra in Illinois. 27th Rept. of the State
+   Entomologist of Illinois, p. 21-55.
+
+FOREL, A. 1878. Der Giftapparat und die Analdrüsen der Ameisen.
+   Zeitschr. wiss. Zool. xxx, p. 28-68.
+
+FOX, G. H. 1880. Photographic illustrations of skin disease. 4^o. New
+   York, E. B. Treat.
+
+FRACKER, S. B. 1914. A systematic outline of the Reduviidæ of North
+   America. Iowa Acad. Sci. p. 217-252.
+
+FRENCH, G. H. 1905. _Nitidula bipustulata_ in a new rôle. Canadian
+   Entomologist, xxxvii, p. 420.
+
+FROST, W. H. 1911. Acute anterior poliomyelitis (_Infantile paralysis_).
+   A précis. Public Health Bul. Washington. No. 44, p. 1-52.
+
+FULLER, C. 1914. The skin maggot of man. S. African Agric. Journ. vii,
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+
+GALLI-VALERIO, B. 1908. Le rôle des arthropodes dans la dissemination
+   des maladies. Centralbl. Bakt. 1 Abt. Ref. xli, p. 353-360.
+
+GERHARDT, C. 1884. Ueber Intermittensimpfungen. Zeitschr. f. klin. Med.
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+
+GIRAULT, A. A. 1905-06. The bed-bug, Clinocoris, (= _Cimex_ = _Acanthia_
+   = _Klinophilos_) _lectularia_ Linnæus. Psyche xii, p. 61-74, vol.
+   xiii, p. 42-58.
+
+---- 1910-14 Preliminary studies on the biology of the bed-bug, _Cimex
+   lectularius_, Linn. Jour. Econ. Biol. v, p. 88-91; vii, p. 163-188;
+   ix, p. 25-45.
+
+GIRAULT, A. A. and STRAUSS, J. F. 1905. The bed-bug, _Clinocoris
+   lectularius_ (Linnæus) and the fowl bug, _Clinocoris columbarius_
+   (Jenyns): host relations, Psyche, xii, p. 117-123.
+
+GIRSCHNER, E. 1893. Beitrag zur Systematik der Musciden. Berliner Ent.
+   Zeitschr. xxxviii, p. 297-312.
+
+---- 1896. Ein neues Musciden-System auf Grund der Thoracalbeborstung
+   und der Segmentierung des Hinterleibes. Wochenschr. für Entom. i, p.
+   12-16, 30-32, 61-64, 105-112.
+
+GOELDI, E. A. 1913. Die sanitarisch-pathologische Bedeutung der Insekten
+   und verwandten Gliedertiere 8^o. Berlin. Friedländer & Sohn. (155
+   p.).
+
+GOLDBERGER, J. 1910. The straw itch. (Dermatitis Schambergi). Public
+   Health Repts., Washington, xxv, p. 779-784.
+
+GOLDBERGER, J. and ANDERSON, J. F. 1912, The transmission of typhus
+   fever, with especial reference to transmission by the head-louse
+   (_Pediculus capitis_). Public Health Repts., Washington, xxvii, p.
+   297-307.
+
+GOLDBERGER, J., WARING, C. H., and WILLETS, D. G. 1914. The treatment
+   and prevention of pellagra. Public Health Repts., Washington, xxix,
+   p. 2821-2826.
+
+GRAHAM-SMITH, G. S. 1913. Flies in relation to disease: non-bloodsucking
+   flies. 8vo. Cambridge Univ. Press. (xiv + 292 p.)
+
+GRASSI, B. 1907. Ricerche sui Flebotomi. Memorie della Società ital.
+   della Scienze, ser. 3 a, xiv, P. 353-394, pls. i-iv.
+
+GRASSI, B. and NOE, G. 1900. Propagation of the filariæ of the blood
+   exclusively by means of the puncture of peculiar mosquitoes. British
+   Med. Journ. ii, p. 1306-1307.
+
+GRIFFITH, A. 1908. Life history of house-flies. Public Health, xxi, p.
+   122-127.
+
+GRÃœNBERG, K. 1907. Die blutsaugenden Dipteren. 8vo. Jena, Fischer. (vi +
+   188 p.).
+
+HADWEN, S. 1913. On "tick paralysis" in sheep and man following bites of
+   _Dermacentor venustus_. Parasitology, vi, p. 283-297.
+
+HADWEN, S. and NUTTALL, G. H. F. 1913. Experimental "tick paralysis" in
+   the dog. Parasitology, vi, p. 298-301.
+
+HALL, M. C. and MUIR, J. F. 1913. A critical study of a case of myasis
+   due to _Eristalis_. Arch. Int. Med., Chicago, xi, p. 193-203.
+
+HAMILTON, J. 1893. Medico-entomology. Entom. News iv, p. 217-219.
+
+HART, C. A. 1895. On the entomology of the Illinois river and adjacent
+   waters. Bul. Ill. State Lab. Nat. Hist., iv, p. 149-273.
+
+HEADLEE, T. J. 1914. Anti-mosquito work in New Jersey. Jour. Econ. Ent.
+   vii, p. 260-268.
+
+HECKER, J. F. C. 1885. The dancing mania of the Middle Ages. Transl. by
+   B. G. Bahington. 8vo. New York, Humboldt Library. (53p.).
+
+HENDEL. 1901. Beitrag zur Kenntniss der Calliphorinen. Wiener Ent.
+   Zeitung. xx, p. 28-33.
+
+HERMS, W. B. 1911. The housefly in its relation to public health. Cal.
+   Agric. Exp. Sta. Bul. 215, p. 511-548.
+
+---- 1913. Malaria: cause and control. 8^o. New York, Macmillan Co. (xi
+   + 163 p.).
+
+HERRICK, G. W. 1903. The relation of malaria to agriculture and other
+   industries of the South. Pop. Sci. Mo. lxii, p. 521-525.
+
+---- 1913. Household insects and methods of control. Cornell Reading
+   Course, (N. Y. State College of Agric.), iii, 47 p.
+
+---- 1914. Insects injurious to the household and annoying to man. 8vo.
+   New York, Macmillan Co. (xvii + 470).
+
+HEWITT, C. G. 1910. The house-fly. A study of its structure,
+   development, bionomics, and economy. 8vo. Manchester Univ. Press.
+   (xiv + 196 p.).
+
+---- 1912. _Fannia_ (_Homalomyia_) _canicularis_ Linn. and _F. scalaris_
+   Fab. Parasitology, v. p. 161-174.
+
+HEYMONS, R. 1901. Biologische Beobachtungen an asiatischen Solifugen,
+   nebst Beiträge zur Systematik derselben. Abl. Ak. Berlin, 1901, Anh.
+   i, 1-65 p.
+
+HIGGINS, F. W. 1891. Dipterous larvæ vomited by a child. Insect Life,
+   Washington. iii, p. 396-397.
+
+HINDLE, E. 1911 a. The relapsing fever of tropical Africa. A Review.
+   Parasitology, iv, p. 183-203.
+
+---- 1911 b. On the life cycle of _Spirochæta gallinarum_. ibid., iv. p.
+   463-477.
+
+HINDLE, E. and MERRIMAN, G. 1914. The range of flight of _Musca
+   domestica_. Journ. of Hygiene, xiv. p. 23-45.
+
+HINE, J. S. 1903. Tabanidæ of Ohio. Papers Ohio Acad. Sci. No. 5, 55 p.
+
+---- 1906. Habits and life-histories of some flies of the family
+   Tabanidæ. U. S. Dept. Agric. Bur. Ent. tech. bul. 12, p. 19-38.
+
+---- 1907. Second report upon the horse-flies of Louisiana. La. Stat.
+   Exp. Bul. 93, p. 1-59.
+
+HODGE, C. F. 1910. A practical point in the study of the typhoid, or
+   filth-fly. Nature Study Review, vi, p. 195-199.
+
+---- 1913. The distance house-flies, blue-bottles, and stable flies may
+   travel over water. Science, n. s. xxxviii, p. 513.
+
+HONEIJ, J. A. and PARKER, R. R. 1914. Leprosy: flies in relation to the
+   transmission of the disease. Journ. Med. Research, Boston, xxx, p.
+   127-130.
+
+HOOKER, W. A. 1908 a. Life history, habits, and methods of study of the
+   Ixodoidea. Jour. Econ. Ent. i, p. 34-51.
+
+---- 1908 b. A review of the present knowledge of the rôle of ticks in
+   the transmission of disease. ibid., i, p. 65-76.
+
+HOPE, F. W. 1837. On insects and their larvæ occasionally found in the
+   human body. Trans. Ent. Soc., London, ii, p. 256-271.
+
+HOUGH, G. DE N. 1899 a. Synopsis of the Calliphorinæ of the United
+   States. Zoological Bulletin, ii, p. 283-290.
+
+---- 1899 b. Some Muscinæ of North America, Biological Bulletin i, p.
+   19-33.
+
+---- 1899 c. Some North American Genera of Calliphorinæ. Entom. News,
+   x, p. 62-66.
+
+HOVARTH, G. 1912. Revision of the American Cimicidæ. Ann. Mus. Nat.
+   Hungarici, x, p. 257-262.
+
+HOWARD, C. W. 1908. A list of the ticks of South Africa, with
+   descriptions and keys to all the forms known. Ann. Transvaal Mus. 1,
+   p. 73-170.
+
+HOWARD, C. W. and CLARK, P. F. 1912. Experiments on insect transmission
+   of the virus of poliomyelitis. Journ. Exper. Med. xvi, p. 805-859.
+
+HOWARD, L. O. 1899. Spider bites and kissing bugs. Pop. Sci. Mo. lv, p.
+   31-42.
+
+---- 1900. A contribution to the study of the insect fauna of human
+   excrement. Proc. Wash. Acad. Sci. ii, p. 541-604.
+
+---- 1901. Mosquitoes, how they live, how they carry disease, how they
+   are classified, how they may be destroyed. 8vo. New York, Doubleday,
+   Page & Co. (xv + 241 p.)
+
+---- 1909. Economic loss to the people of the United States, through
+   insects that carry disease. U. S. Dept. Agric. Bur. of Ent. Bul. 78,
+   p. 1-40.
+
+HOWARD, L. O., DYAR, H. G. and KNAB, F. 1913-. The mosquitoes of North
+   and Central America and the West Indies. Vol. I. A general
+   consideration of mosquitoes, their habits, and their relations to the
+   human species. 4^o. Carnegie Institution of Washington (vii + 520
+   p.).
+
+HOWARD, L. O. and MARLATT, C. L. 1902. The principal household insects
+   of the United States. U. S. Dept. Agric., Bur. Ent. Bul. 4.
+
+HUEBNER, W. 1907. Ueber das Pfeilgift der Kalahari. Arch. exper. Path.
+   und Pharm., lvii, p. 358-366.
+
+HUNTER, S. J. 1913. Pellagra and the sand-fly. Jour. econ. Ent. vi, p.
+   96-99.
+
+HUNTER, W. D. 1913. American interest in medical entomology. Jour. econ.
+   Ent. vi, p. 27-39.
+
+HUNTER, W. D. and BISHOPP, F. C. 1910. Some of the more important ticks
+   of the United States. U. S. Dept. Agric. Yearbook 1910, p. 219-230,
+   pls. xv-xvi.
+
+---- 1911. The Rocky Mountain spotted fever tick. With special reference
+   to the problem of its control in the Bitter Root Valley in Montana.
+   U. S. Dept. Agric., Bur. Ent. Bul. 105, p. 1-47.
+
+HUTCHISON, R. H. 1914. The migratory habit of housefly larvæ as
+   indicating a favorable remedial measure. An account of progress. U.
+   S. Dept. Agric., Bul. 14, p. 1-11.
+
+JENNINGS, A. H. 1914. Summary of two years' study of insects in relation
+   to pellagra. Journ. of Parasitology, i, p. 10-21.
+
+JENNINGS, A. H. and KING, W. V. 1913. One of the possible factors in the
+   causation of pellagra. Journ. Amer. Med. Assoc., lx, p. 271-274.
+
+JEPSON, F. P. 1909. Notes on colouring flies for purposes of
+   identification. Rep't to the Local Gov't Board on Publ. Health, n. s.
+   16, p. 4-9.
+
+JOHANNSEN, O. A. 1903. Aquatic Nematocerous Diptera. N. Y. State Mus.
+   Bul., 68, p. 328-448, pls. 32-50.
+
+---- 1905. Aquatic Nematocerous Diptera II. (Chironomidæ). ibid. 86, p.
+   76-330, pls. 16-37.
+
+---- 1908. North America Chironomidæ. ibid., 124, p. 264-285.
+
+---- 1911. The typhoid fly and its allies. Maine Agric. Exp. Sta. Bul.,
+   401, p. 1-7.
+
+---- 1911. Simulium and pellagra. Insect Notes for 1910. Maine Agr.
+   Exper. Station. Bul. 187, p. 4.
+
+KELLOGG, V. L. 1915. Spider poison. Jour. of Parasitology, i, p. 107+
+
+KELLY, H. A. 1907. Walter Reed and yellow fever. 8vo. New York, McClure,
+   Phillips & Co. (xix + 310 p.).
+
+KEPHART, CORNELIA F. 1914. The poison glands of the larva of the
+   browntail moth (Euproctis chrysorrhoea Linn.). Journ. Parasit., i,
+   p.
+
+KIEFFER, J. J. 1906. Chironomidæ. Genera Insectorum. Fasc. 42, p. 1-78.
+
+---- 1913. Nouv. étude sur les Chironomides de l'Indien Museum de
+   Calcutta. Records of the Indian Mus., ix, p. 119-197.
+
+KING, A. F. A. 1883. Insects and disease--mosquitoes and malaria. Pop.
+   Sci. Mo. xxiii, p. 644-658.
+
+KIRKLAND, A. H. 1907. Second annual report of the Superintendent for
+   suppressing the gypsy and browntail moths. 8vo. Boston. 170 p.
+
+KLEINE, E. 1909. Postive Infektionsversuche mit _Trypanosoma brucei_
+   durch _Glossina palpalis._ Deutsche med. Wochenschr., xxxv, p.
+   469-470.
+
+   Weitere wissenschaftliche Beobachtungen über die Entwicklung von
+      Trypanosomen in Glossinen. ibid. p. 924-925.
+
+   Weitere Untersuchungen über die Ætiologie der Schlafkrankheit. ibid.,
+      p. 1257-1260.
+
+   Weitere Beobachtungen über Tsetsefliegen und Trypanosomen. ibid., p.
+      1956-1958.
+
+KLING, C. and LEVADITI, C. 1913. Études sur la poliomyélite aiguë
+   épidémique. Ann. Inst. Pasteur, xxvii, p. 718-749, 739-855.
+
+KNAB, F. 1912. Unconsidered factors in disease-transmission by
+   blood-sucking insects. Journ. Econ. Ent., v, p. 196-200.
+
+---- 1913 a. The species of Anopheles that transmit human malaria. Amer.
+   Journ. Trop. Dis. and Preventive Med., i, p. 24-43.
+
+---- 1913 b. Anopheles and malaria. ibid., i, p. 217.
+
+---- 1913 c. The life history of _Dermatobia hominis_. ibid., i, p.
+   464-468.
+
+KNAB, F. See Howard, Dyar, and Knab.
+
+KOBERT, R. 1893. Lehrbuch der Intoxikationen. 4^o. Stuttgart, Enke. (xxii
+   + 816 p.). 2d ed. in 2 vols., 1906.
+
+---- 1901. Beiträge zur Kenntniss der Giftspinnen. 8^o. Stuttgart, Enke.
+   (viii + 191 p.).
+
+KOLBE, H. J. 1894. Der Pfeilgiftkäfer der Kalahari-Wüste, _Diamphidia
+   simplex_. Stett. Ent. Zeitg., iv, p. 79-86.
+
+KRAUSE, M. 1907. Untersuchungen über Pfeilgifte aus unseren
+   africanischen Kolonien. Verhand. deutsche Kolonien kong. 1905. p.
+   264-288.
+
+LALLIER, P. 1897. Étude sur la myase du tube digestif chez l'homme.
+   Thesis, Paris, 8^o. 120 p.
+
+LANGER, J. 1897. Ueber das Gift unserer Honigbiene. Archiv. exper. Path.
+   und Pharm., xxxviii, p. 381-396.
+
+LAVINDER, C. H. 1911. Pellagra: a précis. U. S. Publ. Health Service
+   Bul. 48, 37 p.
+
+LEIDY, J. 1847. History and anatomy of the hemipterous genus
+   _Belostoma_. Journ. Acad. Philad. (2), i, p. 57-67.
+
+LEIPER, R. T. 1907. The etiology and prophylaxis of dracontiasis.
+   British Med. Journ. 1907, p. 129-132.
+
+LEISHMAN, W. B. 1910 a. Observations on the mechanism of infection in
+   tick fever and on the hereditary transmission of _Spirochæta duttoni_
+   in the tick. Trans. Soc. Trop. Med. Hyg., iii, p. 77-95. Abstr. in
+   Bul. Inst. Pasteur, viii, p. 312-313.
+
+---- 1910 b. On the hereditary transmission and mechanism of infection
+   in tick fever and on the hereditary transmission of _Spirochæta
+   duttoni_ in the tick. Lancet., clxxvii, p. 11.
+
+LINNELL, R. McC. 1914. Notes on a case of death following the sting of a
+   scorpion. Lancet, 1914, p. 1608-1609.
+
+LIVINGSTONE, D. 1857. Missionary travels and researches in South Africa.
+
+LUCAS, H. 1843. (note) _Latrodectus malmignatus_ Bul. Soc. Ent., France,
+   1843, p. viii.
+
+LUDLOW, C. S. 1914. Disease bearing mosquitoes of North and Central
+   America, the West Indies and the Philippine Islands. War Dept.,
+   Office of Surgeon General. Bul. No. 4, 1-96.
+
+LUGGER, 1896. Insects injurious in 1896. Agr. Exp. Sta. Bul. 48. p. 33
+   to 270.
+
+MacCALLUM, W. C. 1898. On the hæmatozoan infection of birds. Journ. Exp.
+   Med. iii, p. 117.
+
+MacGREGOR, M. E. 1914. The posterior stigmata of dipterous larvæ as a
+   diagnostic character. Parasitology, vii, p. 176-188.
+
+MacLOSKIE, G. 1888. The poison apparatus of the mosquito. Amer.
+   Naturalist, xxii, p. 884-888.
+
+MALLOCH, J. P. 1913. American black-flies or Buffalo gnats. U. S. Dept.
+   Agric. Bur. Ent. Tech. Bul. 26, p. 1-72.
+
+---- 1914. Notes on North American Diptera. Bul. Illinois State Lab.
+   Nat. Hist., x, p. 213-243.
+
+MANSON, P. 1911. Tropical diseases: a manual of the diseases of warm
+   climates. 8^o. London, Cassell & Co. (xx + 876 p.). 4 ed. (1907).
+   Reprinted.
+
+MARCHOUX, E. and COUVY, L. 1913. Argas et spirochætes (1 mémoire). Les
+   granules de Leishman. Ann. Inst. Pasteur, xxvii, p. 450-480. 2
+   mémoire. Le virus chez l'acarien. ibid. p. 620-643.
+
+MARCHOUX, E. and SELIMBENI, A. 1903. La spirillose des poules. Ann.
+   Inst. Pasteur, xvii, p. 569-580.
+
+MARCHOUX, E. and SIMOND, P. L. 1905. Études sur la fièvre jaune. Ann.
+   Inst. Pasteur, xx, pp. 16-40, 104-148, 161-205.
+
+MARLATT, C. L. 1902. (See Howard, L. O. and Marlatt, C. L.)
+
+---- 1907. The bed-bug (_Cimex lectularius_ L.) U. S. Dept. Agric., Bur.
+   Ent., Circ. No. 47, revised ed., 8 pp.
+
+MARTIN, G. LEBOEUF, and ROUBAUD. 1909. Rapport de la mission d'études de
+   la maladie du sommeil au Congo français. 4^o. Paris, Masson & Cie.
+   (vi + 722 p., 8 pls. and map.).
+
+MAVER, MARIA B. 1911. Transmission of spotted fever by other than
+   Montana and Idaho ticks. Journ. Infec. Dis., viii, p. 322-326.
+
+McCLINTIC, T. B. 1912. Investigations of and tick eradications in Rocky
+   Mountain spotted fever. Publ. Health Repts., Washington, xxvii, p.
+   732-760.
+
+MECKEL, H. 1847. Uber schwarzes Pigment in der Milz und im Blute einer
+   Geisteskranken. Allgem. Zeitschr. f. Psychiatrie, iv, p. 198-226.
+
+MEGNI, P. 1906. Les insectes buveurs de sang. 12mo. Paris, Rudeval. (150
+   p.).
+
+MELNIKOFF, N. 1869. Ueber die Jugendzustände der _Tænia cucumerina_.
+   Arch. f. Naturg., xxxv, p. 62-70.
+
+MENSE, C. 1913. Handbuch der Tropenkrankheiten. 1 Band. 4^o. Leipzig,
+   Barth (xv + 295 p.) Entomological parts by A. Eysell, and by Doerr
+   and Russ.
+
+MINCHIN, E. A. 1912. An introduction to the study of the Protozoa, with
+   special reference to the parasitic forms. 8^o. London. Arnold (xi +
+   517 p.).
+
+MITCHELL, EVELYN G. 1907. Mosquito life. 8vo. New York, Putmans. (xxii +
+   281 p.).
+
+MITZMAIN, M. B. 1910. General observations on the bionomics of the
+   rodent and human flies. U. S. Publ. Health Service. Bul., 38, p.
+   1-34.
+
+---- 1912. The rôle of _Stomoxys calcitrans_ in the transmission of
+   _Trypanosoma evansi_. Philippine Journ. Sci., vii, p. 475-519, 5 pls.
+
+---- 1913 a. The biology of _Tabanus striatus_ Fabricius, the horsefly
+   of the Philippines. ibid., vii, B. p. 197-221.
+
+---- 1913 b. The mechanical transmission of surra. ibid., viii, sec. B.,
+   p. 223-229.
+
+---- 1914 a. Experimental insect transmission of anthrax. U. S. Public
+   Health Repts. xxix, p. 75-77.
+
+---- 1914 b. I. Collected studies on the insect transmission of
+   _Trypanosoma evansi_. II. Summary of experiments in the transmission
+   of anthrax by biting flies. U. S. Pub. Health Service, Hyg. Lab.
+   Bul., 94, p. 1-48.
+
+MIYAKE, H. and SCRIBA, J. 1893. Vorläufige Mitteilung über einen neuen
+   Parasit des Menschen. Berl. klin. Wochenschr., xxx, p. 374.
+
+MOLLERS, B. 1907. Experimentelle Studien über die Uebertragung des
+   Rückfallfiebers durch Zecken. Zeitschr. für Hyg. u.
+   Infektionskrankheiten, lviii, p. 277-286.
+
+MOTE, D. C. 1914. The cheese-skipper (_Piophila casei_). Ohio Naturalist
+   xiv, p. 309-310.
+
+NEIVA, A. 1910. Beiträge zur Biologie der _Conorhinus megistus_ Burm.
+   Memorias de Institute Oswaldo Cruz., ii, p. 206-212.
+
+NEVEU-LEMAIRE, M. 1907. Un nouveau cas de parasitisme accidental d'un
+   myriapode dans le tube digestif de l'homme, C. R. Soc. der Biol.,
+   lxiii p. 305-308.
+
+---- 1908. Précis de parasitologie humaine. 8vo. Paris, Rudeval. (v +
+   712 p.).
+
+NEWSTEAD, R. 1911. The papataci flies (Phlebotomus) of the Maltese
+   Islands. Bul. of Ent. Research, ii, p. 47-78, pls. 1-3.
+
+NICOLL, W. 1911. On the part played by flies in the disposal of the eggs
+   of parasitic worms. Repts. to the Local Gov't. Board on Publ. Health
+   and Med. Subjects, n. s. No. 53, p. 13-30.
+
+NICOLLE, C. 1910, Recherches expérimentales sur la typhus exanthématique
+   entreprises à l'Institut Pasteur de Tunis pendant l'année 1909. Ann.
+   Inst. Pasteur, xxiv, p. 243-275.
+
+---- 1911. Recherches expérimentales sur la typhus exanthématique
+   entreprises à l'Institut Pasteur de Tunis pendant l'année 1910.
+   ibid., xxv, p. 1-55, 97-154.
+
+NICOLLE, C., BLAIZOT, A., and CONSEIL, E. 1912 a. Étiologie de la fièvre
+   récurrente. Son mode de transmission par le pou. C. R. Acad. Sci.,
+   cliv, p. 1636-1638.
+
+---- 1912 b. Conditions de transmission de la fièvre récurrente par le
+   pou. ibid., clv., p. 481-484.
+
+NICOLLE, C. and CATOUILLARD, G. 1905. Sur le venin d'un scorpion commun
+   de Tunisie (_Heterometrus maurus_). C. R. Soc. Biol. lviii: p.
+   100-102.
+
+NOE, G. 1901. Sul ciclo evolutivo della _Filaria bancrofti_ e delta
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+
+NORMAN, W. W. 1896. The effect of the poison of centipedes. Trans. Texas
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+
+NUTTALL, G. H. F. 1899. On the rôle of insects, arachnids, and myriapods
+   as carriers in the spread of bacterial and parasitic diseases of man
+   and animals. Johns Hopkins Hosp. Repts., viii, 154 p., 3 pls.
+
+---- 1908 a. On the behavior of Spirochætæ in _Acanthia lectularia_.
+   Parasitology, i, p. 143-151.
+
+---- 1908 b. The transmission of _Trypanosoma lewisi_ by fleas and lice.
+   ibid., i, p. 296-301.
+
+---- 1908 c. The Ixodoidea or ticks, spirochætosis in man and animals,
+   piroplasmosis. Journ. Roy. Inst. Publ. Health, xvi, p. 385-403,
+   449-464, 513-526.
+
+---- 1914. Tick paralysis in man and animals. Parasitology, vii, p.
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+
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+   domestica_ and allied (non-biting) flies in the spread of infective
+   diseases. A summary of our present knowledge. Rept. to the Local
+   Gov't Board on Publ. Health and Med. Subjects, n. s. 16, p. 13-41.
+
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+   i, ii, and iii.
+
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+   Krebsbildungen in der Mamma. Berliner klin. Wochenschr., xlvii, p.
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+
+OSBORN, HERBERT. 1896. Insects affecting domestic animals. U. S. Dept.
+   Agric., Bur. of Ent. Bul., 5, n. s., 302 p.
+
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+   v, p. 158-169.
+
+OSLER, W. 1887. An address on the Hæmatozoa of malaria. British Med.
+   Jour. i. p. 556.
+
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+
+OUDEMANS, A. C. 1910. Neue Ansichten über die Morphologie des
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+
+PATTON, W. S. 1907. Preliminary report on the development of the
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+
+PATTON, W. S. and CRAGG, F. W. 1913. A textbook of medical entomology.
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+
+PAWLOWSKY, E. 1906. Ueber den Steck- und Saug-apparat der Pediculiden.
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+
+PAWLOWSKY, E. 1913. Scorpiotomische Mitteilungen. I. Ein Beitrag zur
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+
+PEPPER, W., SCHNAUSS, F. W., and SMITH, A. J. 1908. Transient parasitism
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+
+PETROVSKAIA, MARIA. 1910. Sur les myases produites chez l'homme par les
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+
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+
+---- 1912. Effets physiologiques du venin de la Mygale de Haïti, le
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+
+PORTSCHINSKY, I. A. 1908. _Rhinœstrus purpureus_, a parasite of
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+   Miss S. L. Weissman, in library of Ent. Dept., Cornell University.
+
+---- 1910. Biology of _Stomoxys calcitrans_ and other coprophagous
+   flies. Monograph in Russian. Mss. summarized transl. by Miss S. L.
+   Weissman, in Library of Ent. Dept., C. U.
+
+---- 1911. _Gastrophilus intestinalis_. Mss. transl. by Miss S. L.
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+
+---- 1913 a. The sheep gad-fly, _Oestrus ovis_, its life, habits,
+   methods of combating it, and its relation to man. Russian. Mss.
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+   C. U.
+
+---- 1913 b. _Muscina stabulans_. A monograph in Russian. Mss., trans.
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+
+PROWAZEK, S. 1905. Studien über Säugetiertrypanosomen. Arb. aus dem
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+
+PUSEY, W. A. 1911. The principles and practice of dermatology. 2 ed,
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+
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+
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+
+---- 1911. The life history of a parasitic nematode, _Hebronema muscæ_.
+   Science n. s. xxxiv, p. 690-692.
+
+---- 1913. The life history of _Habronema muscæ_, (Carter), a parasite
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+
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+
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+
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+
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+
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+
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+
+RICARDO, GERTRUDE. 1900. Notes on the Pangoninæ. Ann. and Mag. Nat.
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+
+---- 1901. Further Notes on the Pangoninæ. ibid. viii, p. 286-315.
+
+---- 1904. Notes on the smaller genera of the Tabanidæ. ibid. xiv, P.
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+
+RICKETTS, H. T. 1906-1910. Contributions to medical sciences by Howard
+   Taylor Ricketts. 1870-1910. Univ. of Chicago Press. 1911.
+
+---- 1909. A microorganism which apparently has a specific relationship
+   to Rocky Mountain spotted fever. A preliminary report. Jour. Amer.
+   Med. Assoc. iii, p. 373-380.
+
+---- Spotted fever reports 1 and 2. In the 4th Bien. Rept. State Board
+   of Health, Montana, 1909, p. 87-191.
+
+RICKETTS, H. T. and WILDER, R. M. 1910. The transmission of the typhus
+   fever of Mexico (tabardillo) by means of the louse, _Pediculus
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+
+RILEY, C. V. and HOWARD, L. O. 1889. A contribution to the literature of
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+
+RILEY, W. A. 1906. A case of pseudoparasitism by dipterous larvæ.
+   Canadian Ent. xxxviii, p. 413.
+
+---- 1910 a. Earlier references to the relation of flies to disease.
+   Science n. s. xxxi, p. 263-4.
+
+---- 1910 b. _Dipylidium caninum_ in an American child. Science n. s.
+   xxxi, p. 349-350.
+
+---- 1911. The relation of insects to disease. Cornell Countryman ix, P.
+   51-55.
+
+---- 1912 a. Notes on the relation of insects to disease. 8vo. Ithaca,
+   N. Y. 51 p.
+
+---- 1912 b. Notes on animal parasites and parasitism. 8vo. Ithaca, N.
+   Y. 55 p.
+
+---- 1913. Some sources of laboratory material for work on the relations
+   of insects to disease. Ent. News. xxiv, p. 172-175.
+
+---- 1914. Mr. Nott's theory of insect causation of disease. Jour. of
+   Parasitology. i, p. 37-39.
+
+ROSENAU, M. J. and BRUES, C. T. 1912. Some experimental observations on
+   monkeys, concerning the transmission of poliomyelitis through the
+   agency of _Stomoxys calcitrans_. Monthly Bul. Mass. State Board of
+   Health. Vol. vii, p. 314-317.
+
+ROSS, R. 1904. Researches on Malaria. The Nobel Medical Prize Lecture
+   for 1902, Stockholm, Norstedt & Söner. 89 p. 9 pls. In "Les Prix
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+
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+
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+   Zoologicæ xii, p. 153-174.
+
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+   xii, p. 192-193.
+
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+
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+
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+
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+
+---- 1910. Progress report on the investigation of pellagra. Reprinted
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+   question of carriage by domestic vermin. Résumé in Ann. Inst. Pasteur
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+   volumes. London.
+
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+   par des larves de Diptère. Arch. Parasit. iv, p. 353-361
+
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+   Med. Journ. 1913, p. 847.
+
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+   dans leurs rapports avec la propagation de la peste bubonique. Arch.
+   Parasit. viii, p. 161-349.
+
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+   Parasit., iv. p. 607-614.
+
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+   Journ. of Inf. Dis., x, p. 166-177.
+
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+   Smithsonian Misc. Col., p. 1-138.
+
+---- 1911. Review of work by Pantel and Portchinski on reproductive and
+   early stage characters of Muscoid flies. Proc. Ent. Soc., Washington,
+   xiii, p. 151-170.
+
+---- 1912. Muscoid names. ibid., xiv, p. 45.
+
+---- 1913 a. Preliminary characterization of the vector of verruga,
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+   Washington, i, p. 107-109.
+
+---- 1913 b. The transmission of verruga by _Phlebotomus_. Journ. Amer.
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+
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+
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+
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+
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+
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+   2d Rept. of the Supt. for Suppressing the Gypsy and Brown-tail Moths,
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+
+VAUGHAN,
+
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+   d'un myriapode, (_Chætachlyne vesuviana_) chez l'homme. C. R. Soc.
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+
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+
+VILLENEUVE, J. 1914. Quelques réflexions au sujet de la tribu des
+   Calliphorinæ Bul. Soc. Ent., France, No. 8, p. 256-258.
+
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+   xxii, P. 193-203.
+
+WATSON, J. J. 1910. Symptomology of pellagra and report of cases. Trans.
+   Nat. Conference on Pellagra, Columbia, S. C., Nov. 3 and 4, 1909, p.
+   207-218.
+
+WEED, C. M. 1904. An experiment with black-flies. U. S. Dept. Agric.,
+   Bur. Ent. Bul. n. s., 46, p. 108-109.
+
+WELLMAN, F. C. 1906. Human trypanosomiasis and spirochætosis in
+   Portuguese Southwest Africa, with suggestions for preventing their
+   spread in the Colony. Journ. Hyg., vi, p. 237-345.
+
+WERNER, F. 1911. Scorpions and allied annulated spiders. Wellcome Trop.
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+
+WHITFIELD, A. 1912. A method of rapidly exterminating pediculi capitis.
+   Lancet 1912 (2), p. 1648. See notes.
+
+WILLISTON, S. W. 1908. Manual of the North American Diptera, New Haven,
+   p. 1-405.
+
+WILSON, G. B. and CHOWNING, W. M. 1903. Studies in _Piroplasmosis
+   hominis_. Journ. Inf. Dis., iv, p. 31-57.
+
+WILSON, W. H. 1904. On the venom of scorpions. Rec. Egyptian Gov't
+   School of Medicine, Cairo, ii, p. 7-44.
+
+
+
+
+INDEX
+
+
+Abscess, 178
+
+Acanthia, 87
+
+Acariasis, 58
+
+Acarina, 23, 58, 131, 259
+
+Acarus dysenteriæ, 132
+
+Accidental parasites, 131, 132, 134
+
+Aedes, 194, 293
+
+Aedes calopus, 182, 201, 205, 206, 208
+
+Aedes cantator, 101
+
+Aedes sollicitans, 101
+
+Aedes tæniorhynchus, 101
+
+Aerobic bacteria, 152
+
+Æstivo-autumnal, 186
+
+African Relapsing Fever, 230
+
+Akis spinosa, 177
+
+Alternation of Generations, 175
+
+Amblyomma, 264
+
+Amblyomma americanum, 67
+
+Amblyomma cajennense, 67
+
+American dog tick, 228
+
+Amœboid organism, 189
+
+Anisolabis annulipes, 177
+
+Anterior poliomyelitis, 241
+
+Anopheles, 194, 291
+
+Anopheles crucians, 199
+
+Anopheles maculipennis, 182
+
+Anopheles punctipennis, 198
+
+Anopheles quadrimaculatus, 197
+
+Anopheline, 192
+
+Anthocoris, 279
+
+Anthomyiidæ, 300
+
+Anthomyia, 138
+
+Anthrax, 165
+
+Antipruritic treatment, 72
+
+Ants, 42
+
+Aphiochæta, 295
+
+Apis mellifica, 36
+
+Arachnida, 258
+
+Araneida, 6
+
+Argas, 64
+
+Argas persicus, 63, 235, 237
+
+Argasidæ, 62
+
+Argopsylla, 317
+
+Argus, 259
+
+Arilus, 284
+
+Arthropods, poisonous, 6
+
+Asopia farinalis, 177
+
+Assassin-bugs, 31, 219
+
+Auchmeromyia, 117
+
+Automeris io, 47
+
+Avicularoidea, 12
+
+
+Babesia, 226
+
+Babesia bovis, 223
+
+Babesia ovis, 225
+
+Babesiosis, 221-222
+
+Bacilli, 170
+
+Bacillus icteroides, 202, 205
+
+Bacillus pestis, 166
+
+Bacillus typhosus, 153
+
+Back swimmers, 30
+
+Bdellolarynx, 304
+
+Beauperthuy, Louis Daniel, 2
+
+Bed-bug, 86, 88, 90, 173, 219-220
+
+Bed-bug, cone-nosed, 92
+
+Blister beetles, 54
+
+Belostoma, 28, 277
+
+Belostoma americana, 31
+
+Belostomatidæ, 30
+
+Bengalia, 314
+
+Bird-spiders, 10
+
+Black death, 1, 166
+
+Black flies, 33, 104, 247
+
+Black heads, 80
+
+Blaps mortisaga, 134
+
+Blepharoceridæ, 286
+
+Boophilus, 264
+
+Boophilus annulatus, 67, 223-225
+
+Bot-flies, 112
+
+Blue bottle flies, 140
+
+Brill's disease, 238
+
+Brown-tailed moth, 48
+
+Bruck, 34
+
+Buthus quinquestriatus, 21
+
+
+Cabbage butterfly, 56
+
+Calliphora, 136, 140, 312
+
+Calliphora erythrocephala, 141
+
+Calobata, 296
+
+Camponotinæ, 43
+
+Cancer, 254
+
+Cantharidin, 54
+
+Cantharidin poison, 55
+
+Canthariasis, 134
+
+Capsidæ, 280
+
+Carriers, simple, 4, 144
+
+Carriers of disease, 144
+
+Carrion's fever, 253
+
+Caterpillar rash, 45
+
+Cat flea, 172
+
+Cattle ticks, 222
+
+Causative organism, 170
+
+Cellia, 291
+
+Centipedes, 25, 257
+
+Ceratophyllus, 120, 316
+
+Ceratophyllus acutus, 123
+
+Ceratophyllus fasciatus, 122, 172, 213
+
+Ceratopogon, 108
+
+Cheese-fly, 137
+
+Cheyletus eruditus, 271
+
+Chigger, 60, 70
+
+Chigoes, 126
+
+Chilopoda, 25, 257
+
+Chiracanthium nutrix, 18
+
+Chironomidæ, 107
+
+Chorioptes, 270
+
+Chrysomelid, 55
+
+Chrysomyia, 136, 308
+
+Chrysomyia macellaria, 117, 140
+
+Chrysops, 294
+
+Chylous dropsy, 179
+
+Chyluria, 178
+
+Cicadidæ, 55
+
+Cimex L., 278
+
+Cimex boueti, 92
+
+Cimex columbarius, 92
+
+Cimex hemipterus, 91, 220
+
+Cimex hirundinis, 92
+
+Cimex inodorus, 92
+
+Cimex lectularius, 87, 219
+
+Citheronia regalis, 44
+
+Clinocoris, 87
+
+Coleoptera, 134, 274
+
+Comedons, 80
+
+Complete metamorphosis, 80
+
+Compressor muscle, 20
+
+Compsomyia, 117
+
+Cone-nosed bed-bug, 92
+
+Conjunctivitis, nodular, 52
+
+Conorhinus, 282
+
+Conorhinus megistus, 93, 219-220
+
+Conorhinus rubrofasciatus, 220
+
+Conorhinus sanguisugus, 32, 92
+
+Copra itch, 72
+
+Cordylobia, 118
+
+Coriscus, 280
+
+Coriscus subcoleoptratus, 32
+
+Creeping myasis, 112
+
+Crustacea, 257
+
+Cryptocystis, 176
+
+Cryptotoxic, 54-55
+
+Cteniza sauvagei, 13
+
+Ctenocephalus, 120, 172, 213, 317
+
+Culex, 194, 201, 293
+
+Culex pipiens, 35, 98
+
+Culex quinquefasciatus, 180
+
+Culex sollicitans, 200
+
+Culex territans, 101
+
+Culicidæ, 33, 97
+
+Culicin, 34
+
+Culicoides, 109, 288
+
+Cyclops, 183, 257
+
+Cynomyia, 136, 311
+
+
+Dance, St. Vitus, 8
+
+Dancing mania, 8
+
+Deer-flies, 110
+
+Definitive host, 192
+
+Demodecidæ, 78
+
+Demodex, 259
+
+Demodex folliculorum, 78
+
+Dermacentor, 262
+
+Dermacentor andersoni, 67, 228
+
+Dermacentor occidentalis, 227
+
+Dermacentor variabilis, 67
+
+Dermacentor venustus, 24, 228
+
+Dermanyssidæ, 68
+
+Dermanyssus, 266
+
+Dermanyssus gallinæ, 68
+
+Dermatitis, 72, 77, 85
+
+Dermatobia, 115, 298
+
+Dermatobia cyaniventris, 163
+
+Dermatophilus, 317
+
+Dermatophilus penetrans, 60, 126
+
+Diamphidia simplex, 55
+
+Dimorphism, 65
+
+Direct inoculators, 4
+
+Diplopoda, 25, 257
+
+Diptera, 33, 94, 274
+
+Dipterous Larvæ, 135
+
+Dipylidium, 175, 221
+
+Dipylidium caninum, 4, 175-176
+
+Dog flea, 172
+
+Dracunculus, 257
+
+Dracunculus medinensis, 182
+
+Drosophila, 296
+
+Dum-dum fever, 220
+
+Dysentery, 154
+
+
+Ear-flies, 110
+
+Earwig, 177
+
+Echidnophaga, 317
+
+Echinorhynchus, 185
+
+Elephantiasis, 178-179
+
+Empoasca mali, 33
+
+Empretia, 46
+
+English Plague Commission, 171
+
+Epeira diadema, 18
+
+Epizootic, 170
+
+Eristalis, 137, 295
+
+Essential hosts, 4, 165
+
+Eumusca, 307
+
+European Relapsing Fever, 233
+
+Euproctis chrysorrhœa, 48
+
+Eusimulium, 286
+
+
+Facultative parasites, 131
+
+Fannia, 136, 138, 145, 300
+
+Federal Health Service, 169
+
+Fever, lenticular, 237
+  African Relapsing, 230, 234
+  Carrion's, 253
+  dum-dum, 154
+  European Relapsing, 233
+  pappatici, 96
+  red water, 220
+  Rocky Mt. Spotted, 226
+  three day, 96
+  Typhus, 237
+
+Filaria, 178, 221
+  immitis, 182
+
+Filariasis, 178
+
+Flannel-moth larvæ, 44
+
+Fleas, 119, 166, 213
+  cat, 172
+  dog, 172
+  human, 172, 176
+  rodent, 123, 172
+  rat, 171
+
+Flesope, 125
+
+Formaldehyde, 91
+
+Fomites, 199, 204
+
+Fulgoridæ, 28
+
+Fumigation, 320
+
+
+Gamasid, 68
+
+Gangrene, 129
+
+Gastrophilus, 113, 297
+
+Giant crab spiders, 13
+
+Giant water bugs, 30
+
+Gigantorhynchus, 185
+
+Glossina, 117, 297, 303
+
+Glossina morsitans, 214, 217
+  palpalis, 215, 217, 218
+
+Glyciphagus, 267
+
+Grain moth, 69
+
+Grocer's itch, 72
+
+Guinea-worm, 182
+
+
+Habronema muscæ, 156, 183
+
+Hæmatobia, 166, 304
+  irritans, 146
+
+Hæmatobosca, 304
+
+Hæmatomyidium, 288
+
+Hæmatopinus spinulosus, 213
+
+Hæmatopota, 294
+
+Hæmatosiphon, 279
+
+Hæmoglobinuria, 222
+
+Hæmozoin, 189
+
+Harpactor, 284
+
+Harvest mites, 60
+  effect of, 59
+
+Head-louse, 173
+
+Helminthiasis, 138
+
+Helophilus, 295
+
+Hemiptera, 27, 86, 273-275
+
+Heteropodidæ, 13
+
+Heuchis sanguinea, 55
+
+Hexapod larvæ, 58
+
+Hexapoda, 27, 80, 258
+
+Hippelates, 297
+
+Hippobosca, 285
+
+Histiogaster, 269
+  spermaticus, 132
+
+Homalomyia, 136, 138, 300
+
+Honey bee, 36
+  poison of, 37
+
+Hornets, 43
+
+Horn-fly, 137, 304, 308
+
+Horse-fly, 110, 165
+
+House-fly, 137-139, 144, 183
+  control of, 156, 160
+
+Human flea, 124
+
+Host, definitive, 175
+  intermediate, 175
+  primary, 175
+
+Hyalomma, 264
+  ægypticum, 224-225
+
+Hydrocyanic Acid Gas, 318
+
+Hydrotæa, 300
+
+Hymenolepis diminuta, 176
+
+Hymenoptera, 36, 275
+
+Hypoderma, 113, 298
+  diana, 113
+  lineata, 113
+
+Hypopharynx, 80
+
+
+Immunity from stings, 39
+
+Incomplete metamorphosis, 80
+
+Infantile paralysis, 162, 241
+  splenic, 220
+  Direct inoculation, 164
+
+Insects, 258
+  blood-sucking, 170
+
+Intermediate host, 192, 203
+
+Intestinal infestation, 112, 133
+  myasis, 137
+
+Isosoma, 69
+
+Itch, 73-74
+  mite, 73
+  Norwegian, 77
+
+Ixodes, 260
+  ricinus, 66, 225
+  scapularis, 66
+
+Ixodidæ, 64-65
+
+Ixodoidea, 62
+
+
+Janthinosoma lutzi, 116
+
+Jigger, 60
+
+Johannseniella, 110, 288
+
+Journal of Tropical Medicine and Hygiene, 36
+
+Julus terrestris, 25
+
+June bug, 185
+
+
+Kala-azar, 220
+
+Karakurte, 14
+
+Katipo, 14
+
+King, A. F. A., 3
+
+Kircher, Athanasius, 1, 8
+
+Kissing-bug, 31
+
+
+Labium, 29, 80
+
+Labrum, 28, 80
+
+Lachnosterna, 185
+
+Lælaps, 266
+
+Lagoa crispata, 45
+
+Lamblia intestinalis, 154
+
+Langer, Josef, 37
+
+Larder beetles, 135
+
+Latrodectus, 12, 14, 17
+  mactans, 15
+
+Leishmanioses, 220
+
+Lenticular fever, 237
+
+Lepidoptera, 274
+
+Lepidopterous larvæ, 134
+
+Leprosy, 252
+
+Leptidæ, 112
+
+Leptis, 295
+
+Leptus, 60, 273
+
+Lice, 80
+
+Linguatulina, 258
+
+Liponyssus, 265
+
+LÅ“mopsylla, 172, 317
+
+Lone star tick, 228
+
+Louse, body, 84
+  crab, 85
+  dog, 176
+  head, 82
+  pubic, 85
+
+Lucilia, 136, 312
+
+Lycosa tarantula, 10
+
+Lycosidæ, 10
+
+Lyctocoris, 279
+
+Lygus pratensis, 33
+
+Lymphangitis, 67
+
+Lymph scrotum, 178
+
+Lyperosia, 304
+
+Lyperosiops, 305
+
+
+Macloskie, 34
+
+Maggots, rat-tail, 137
+
+Magnes sive de Arte Magnetica, 8
+
+Malaria, 186
+
+Malmigniatte, 14
+
+Mandibles, 28, 80
+
+Mange, 73-75
+
+Margaropus, 237, 264
+  annulatus, 223
+
+Masked bed-bug hunter, 32
+
+Mastigoproctus giganteus, 19, 80
+
+Maxillæ, 28
+
+Meal infesting species, 135
+
+Melanin granules, 189
+
+Melanolestes, 280
+  picipes, 32
+
+Mena-vodi, 14
+
+Mercurialis, 1
+
+Merozoites, 190
+
+Metamorphosis, 80
+
+Miana bug, 63
+
+Microgametoblast, 192
+
+Midges, 107
+
+Migratory ookinete, 192
+
+Millipedes, 25, 257
+
+Mites, 23, 58
+
+Monieziella, 269
+
+Mosquitoes, 33, 97, 178, 196, 250
+  treatment for bites of, 34, 36, 102
+
+Musca, 137, 307
+  domestica, 139, 145, 146, 157, 162
+
+Muscidæ, 117
+
+Muscina, 137, 146, 307
+  stabulans, 140
+
+Mutualism, 57
+
+Myasis, 112, 135
+  intestinal, 135-140
+  nasal, 141
+
+Mycterotypus, 287
+
+Myiospila, 146, 307
+
+Myriapoda, 225, 132, 257
+
+
+Nagana, 165, 214
+
+Nasal infestation, 114, 133
+
+Necrobia, 135
+
+Nematode parasite, 182
+
+Nepa, 28
+
+Nephrophages sanguinarius, 132
+
+Nettling insects, 43
+  larvæ, poison of, 53
+
+Neurasthenia, 89
+
+Nits, 86
+
+North African Relapsing Fever, 234
+
+Norwegian itch, 77
+
+No-see-ums, 109
+
+Notœdres, 269
+  cati, 78
+
+Notonecta, 28, 277
+
+Notonectidæ, 30
+
+Nott, Dr. Josiah, 2
+
+Nuttall, 34
+
+
+Occipital headaches, 138
+
+Oecacta, 288
+
+Oeciacus, 279
+
+Å’sophageal diverticula, 35
+
+Oestridæ, 112, 136
+
+Oestris ovis, 113
+
+Oestrus, 298
+  oocyst, 192
+  ookinete, 192
+
+Opsicoetes personatus, 32
+
+Opthalmia, 155
+  nodosa, 52
+
+Oriental sore, 221
+
+Ornithodoros, 65, 260
+  moubata, 220, 230
+
+Orthotylus flavosparsus, 33
+
+Ornithomyia, 286
+
+Oroya, 253
+
+Oscinus, 297
+
+Otiobius, 259
+  megnini, 65
+
+Otodectes, 271
+
+
+Pangonia, 294
+
+Pappatici fever, 96
+
+Parasimulium, 286
+
+Parasite, 3, 57, 131, 134, 182
+  accidental, 3, 131, 134
+  facultative, 3, 57, 131
+  nematode, 182
+  stationary, 57
+  temporary, 57
+  true, 3
+
+Parasitism, accidental, 134
+
+Pathogenic bacteria, 152
+  organisms, 144, 164
+
+Pawlowsky, 81
+
+Pediculoides, 267
+  ventricosus, 69, 72
+
+Pediculosis, 81
+
+Pediculus, 275
+  corporis, 84, 233, 238
+  humanus, 82, 173
+
+Pellagra, 162, 246
+
+Pernicious fever, 186
+
+Pest, 166
+
+Phidippus audax, 19
+
+Philæmatomyia, 306
+
+Phisalix, 13, 43
+
+Phlebotomus, 289
+  papatasii, 94
+  verrucarum, 254
+  vexator, 95
+
+Phora, 295
+
+Phormia, 136
+
+Phormictopus carcerides, 13
+
+Phthirus pubis, 85, 275
+
+Phortica, 296
+
+Pieris brassicæ, 56
+
+Piophila, 297
+
+Piophila casei, 136, 137
+
+Piroplasmosis, 222
+
+Plague, 166
+  bubonic, 166, 169, 170
+  pneumonic, 167
+
+Plasmodium, 186
+
+Platymetopius acutus, 33
+
+Plica palonica, 83
+
+Pneumonic, 166
+  plague, 167, 173
+
+Poisoning by nettling larvæ, 53
+
+Poison of spiders, 7
+
+Pollenia, 308
+  rudis, 146, 147
+
+Primary gland, 28
+
+Prionurus citrinus, 20
+
+Prosimulium, 286
+
+Protocalliphora, 136, 312
+
+Protozoan blood parasite, 165
+
+Pseudo-tubercular, 52
+
+Psorophora, 293
+
+Psoroptes, 270
+
+Psychodidæ, 94
+
+Pulex, 120, 124, 126, 172, 317
+  cheopis, 172
+  irritans, 124
+  penetrans, 126
+  serraticeps, 120
+
+Pulvillus, 150
+
+Punkies, 109
+
+Pycnosoma, 308
+
+
+Rasahus, 280
+  thoracicus, 32
+
+Rat fleas, 120, 124, 171
+
+Rat louse, 213
+
+Red bugs, 70-72
+
+Reduviidæ, 31
+
+Reduviolus, 280
+
+Reduvius, 282
+  personatus, 32
+
+Redwater fever, 222
+
+Relapsing fever, 230, 233
+
+Rhinœstrus nasalis, 115
+
+Rhipicentor, 264
+
+Rhipicephalus, 264
+
+Rhizoglyphus, 269
+
+Rhodnius, 281
+
+Rocky Mountain Spotted Fever, 226
+  spotted fever tick, 67
+
+Russian gad-fly, 115
+
+
+St. Vitus's or St. John's dance, 8
+
+Salivary syringe, 28
+
+Sand-flies, 109, 250
+
+Sanguinetti, 11
+
+Sarcophaga, 136, 142, 143
+
+Sarcophila, 302
+
+Sarcopsylla, 317
+  penetrans, 126
+
+Sarcoptes, 270
+  minor, 78
+  scabiei, 73
+
+Sarcoptidæ, 72
+
+Scabies, 72, 73, 74, 75
+
+Scaurus striatus, 177
+
+Schaudinn, 34
+
+Schizont, 189, 190
+
+Scholeciasis, 134
+
+Scolopendra morsitans, 26
+
+Scorpions, 20
+  poison of, 21
+
+Screw worm fly, 140
+
+Sepsidæ, 296
+
+Sepsis, 136, 297
+
+Shipley, 34
+
+Sibine, 46
+
+Silvius, 294
+
+Simple carriers, 4, 144
+
+Simuliidæ, 33, 104
+
+Simulium, 247, 249, 286, 321
+  pictipes, 104
+
+Siphonaptera, 119, 274, 316
+
+Siphunculata, 80, 275
+
+Sitotroga cerealella, 69
+
+Skippers, 137
+
+Sleeping sickness, 166, 215
+
+Snipe-flies, 112
+
+Solpugida, 22
+
+Spanish fly, 54
+
+Spermatozoa, 192
+
+Spinose ear-tick, 65
+
+Spirochæta, 35
+  berberi, 234
+  duttoni, 234
+
+Spirochætosis, 235
+
+Sporozoite, 189
+
+Spotted fever, 67, 226
+
+Squirrel flea, 123
+
+Stable-fly, 137, 160, 163, 165
+
+Stegomyia, 182, 293
+  calopus, 206
+  fasciata, 206
+
+Stomoxys, 137, 305
+  calcitrans, 117, 146, 160, 161, 165, 242
+
+Straw-worm, 69
+
+Stygeromyia, 305
+
+Sucking stomach, 35
+
+Sulphur ointment, 77
+
+Surra, 165
+
+Symbiosis, 57
+
+Symphoromyia, 112, 295
+
+
+Tabanidæ, 110
+
+Tabanus, 110, 166, 294
+  striatus, 165
+
+Taenia, 175
+
+Tapeworm, 4, 176
+
+Tarantella, 8
+
+Tarantism, 8
+
+Tarantula, 10
+
+Tarsonemidæ, 69
+
+Tarsonemus, 267
+
+Tenebrionid beetles, 127
+
+Tersesthes, 110, 288
+
+Tetanus, 129
+
+Tetranychus, 273
+
+Texas fever, 220-223
+
+Three-day fever, 96
+
+Tick, 23, 226
+  bites, Treatment of, 68
+  fever, 230
+  paralysis, 67
+
+Treatment,
+  Bee stings, 36, 41
+  Bites of,
+    Bed-bugs, 90, 93
+    Blackflies, 107
+    Buffalo flies, 107
+    Bugs, 31, 33
+    Centipedes, 26, 27
+    Chiggers, 127
+    Chigoes, 127
+    Fleas, 127
+    Harvest mites, 61
+    Jiggers, 129
+    Lice, 83, 85
+    Mosquitoes, 34, 36, 102
+    Phlebotomus flies, 97
+    Sand flies, 96, 107, 109
+    Scorpions, 22, 23
+    Spiders, 19
+    Ticks, 61, 68, 72
+    Ticks, ear, 65
+  Blister beetle poison, 55
+  Brown-tail moth rash, 45
+  Cantharidin poison, 55
+  Caterpillar rash, 45
+  Ear ticks, 65
+  House fly control, 156, 160
+  Itch, 77
+  Itch, grocer's, 72
+  Lice, 85
+  Nasal myasis, 143
+  Rocky Mt. spotted fever, 228, 229
+  Rash, caterpillar, 45
+  Scabies, 77
+  Sleeping sickness control, 218
+  Spotted fever, 228, 229
+  Stings, bee, 36, 41
+  Typhus fever, prophylaxis, 239
+
+Trichodectes canis, 176
+
+Trichoma, 82
+
+Trineura, 295
+
+Trochosa singoriensis, 11
+
+Trombidium, 60, 273
+
+True insects, 80
+
+Trypanosoma, 35
+
+Trypanosoma, brucei, 165
+
+Trypanosoma cruzi, 219
+
+Trypanosoma lewisi, 213
+
+Trypanosomiases, 212
+
+Trypanosomiasis, 165, 219
+
+Tsetse flies, 117, 166, 214, 219
+
+Tsetse flies disease, 165
+
+Tuberculosis, 155
+
+Tumbu-fly, 118
+
+Tydeus, 271
+
+Typhoid, 155
+
+Typhoid fever, 154
+
+Typhus, 237
+
+Typhus fever, 237
+
+Tyroglyphus, 72, 131, 268
+
+Dr. Tyzzer, 49
+
+
+Uranotænia, 292
+
+
+Vancoho, 14
+
+Varicose groin glands, 178
+
+Verruga peruviana, 253
+
+Vescicating insects, 54
+
+
+Wanzenspritze, 29
+
+Warble-flies, 112
+
+Wasps, 43
+
+Whip-scorpions, 19
+
+Wohlfahrtia, 143, 302
+
+Wolf-spiders, 10
+
+Wyeomyia smithii, 101, 293
+
+
+Xenopsylla, 172, 317
+
+Xenopsylla cheopis, 171, 124
+
+Xestopsylla, 317
+
+
+Yaws, 2
+
+Yellow fever, 196, 203, 205
+
+
+
+
+TRANSCRIBER'S NOTES
+
+The following discrepancies in the text are as in the original:
+
+  The inconsistent hyphenation of the following:
+    assassin-bugs/assassin bugs;
+    bedbug/bed-bug (and bedbugs);
+    beekeeper/bee-keeper (and beekeepers);
+    blackflies/black-flies;
+    blow-flies/blow flies;
+    bluebottles/blue-bottles;
+    bot-flies/bot flies;
+    bristlelike/bristle-like;
+    browntail/brown-tail;
+    coextensive/co-extensive;
+    deer-flies/deer flies;
+    dorsocentral/dorso-central;
+    ectoparasites/ecto-parasites;
+    endoparasites/endo-parasites;
+    flesh-fly/flesh fly (and flesh flies);
+    hotbed/hot-bed;
+    housefly/house-fly (and houseflies);
+    horsefly/horse-fly (and horse flies);
+    horse-manure/horse manure;
+    midsummer/mid-summer;
+    preeminently/pre-eminently;
+    sandfly/sand-fly (and sandflies);
+    screw-worm fly/screw worm fly;
+    stable-fly/stable fly;
+    subequal/sub-equal;
+    subfamily/sub-family;
+    subtropical/sub-tropical;
+    tapeworm/tape-worm (and tapeworms);
+    today/to-day;
+    tsetse-flies/tsetse flies;
+    widespread/wide-spread;
+    wormlike/worm-like.
+
+  Inconsistent use of diaeresis in Aëdes/Aedes
+
+  Inconsistent spelling of the following:
+    defence/defense;
+    disc/disk;
+    hemolysis/hæmolysis;
+    hemolytic/hæmolytic;
+    hexapod/hexopod;
+    Levaditi/Lavaditi;
+    metalescent/metallescent;
+    Mitzmain/Mitzman;
+    Neveau-Lemaire/Neveau-Lamaire;
+    offence/offense;
+    Phthirus/Phthirius
+    Portschinsky/Portchinsky/Portchinski;
+    travelled/traveled;
+    ventra-/ventro-;
+    Villot/Villet;
+    Wohlfartia/Wohlfahrtia;
+
+  Inconsistent use of ligatures in Taenia/Tænia
+
+toxine, insiduous, efficaceous, cyanid are spelt as in the original
+
+In the first paragraph of chapter XII, "the student might not be lead"
+is as in the original. Lead perhaps should be led
+
+There is no Figure 147 in the original
+
+In the bibliography, the entry for Vaughan without a text specified is
+as in the original
+
+
+
+
+
+End of the Project Gutenberg EBook of Handbook of Medical Entomology, by 
+William Albert Riley and Oskar Augustus Johanssen
+
+*** END OF THIS PROJECT GUTENBERG EBOOK HANDBOOK OF MEDICAL ENTOMOLOGY ***
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diff --git a/34279-0.zip b/34279-0.zip
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+++ b/34279-0.zip
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@@ -0,0 +1,16497 @@
+The Project Gutenberg EBook of Handbook of Medical Entomology, by 
+William Albert Riley and Oskar Augustus Johanssen
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Handbook of Medical Entomology
+
+Author: William Albert Riley
+        Oskar Augustus Johanssen
+
+Release Date: November 11, 2010 [EBook #34279]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK HANDBOOK OF MEDICAL ENTOMOLOGY ***
+
+
+
+
+Produced by Bryan Ness, Iris Schimandle, Brownfox and the
+Online Distributed Proofreading Team at http://www.pgdp.net
+(This file was produced from images generously made
+available by The Internet Archive/American Libraries.)
+
+
+
+
+
+Transcriber's Note: Barring a few obvious typos, the text has been left
+as printed.
+
+
+
+
+[Illustration: Some early medical entomology. Athanasius Kircher's
+illustration of the Italian tarantula and the music prescribed as an
+antidote for the poison of its bite. (1643).]
+
+
+
+
+HANDBOOK OF MEDICAL
+
+ENTOMOLOGY
+
+WM. A. RILEY, PH.D.
+
+Professor of Insect Morphology and Parasitology, Cornell University
+
+and
+
+O. A. JOHANNSEN, PH.D.
+
+Professor of Biology, Cornell University
+
+[Illustration]
+
+ITHACA, NEW YORK
+
+THE COMSTOCK PUBLISHING COMPANY
+
+1915
+
+
+COPYRIGHT, 1915
+
+BY THE COMSTOCK PUBLISHING COMPANY,
+
+ITHACA, N. Y.
+
+
+Press of W. F. Humphrey
+Geneva, N. Y.
+
+
+
+
+PREFACE
+
+
+The Handbook of Medical Entomology is the outgrowth of a course of
+lectures along the lines of insect transmission and dissemination of
+diseases of man given by the senior author in the Department of
+Entomology of Cornell University during the past six years. More
+specifically it is an illustrated revision and elaboration of his "Notes
+on the Relation of Insects to Disease" published January, 1912.
+
+Its object is to afford a general survey of the field, and primarily to
+put the student of medicine and entomology in touch with the discoveries
+and theories which underlie some of the most important modern work in
+preventive medicine. At the same time the older phases of the
+subject--the consideration of poisonous and parasitic forms--have not
+been ignored.
+
+Considering the rapid shifts in viewpoint, and the development of the
+subject within recent years, the authors do not indulge in any hopes
+that the present text will exactly meet the needs of every one
+specializing in the field,--still less do they regard it as complete or
+final. The fact that the enormous literature of isolated articles is to
+be found principally in foreign periodicals and is therefore difficult
+of access to many American workers, has led the authors to hope that a
+summary of the important advances, in the form of a reference book may
+not prove unwelcome to physicians, sanitarians and working
+entomologists, and to teachers as a text supplementing lecture work in
+the subject.
+
+Lengthy as is the bibliography, it covers but a very small fraction of
+the important contributions to the subject. It will serve only to put
+those interested in touch with original sources and to open up the
+field. Of the more general works, special acknowledgment should be made
+to those of Banks, Brumpt, Castellani and Chalmers, Comstock, Hewitt,
+Howard, Manson, Mense, Neveau-Lemaire, Nuttall, and Stiles.
+
+To the many who have aided the authors in the years past, by suggestions
+and by sending specimens and other materials, sincerest thanks is
+tendered. This is especially due to their colleagues in the Department
+of Entomology of Cornell University, and to Professor Charles W. Howard,
+Dr. John Uri Lloyd, Mr. A. H. Ritchie, Dr. I. M. Unger, and Dr. Luzerne
+Coville.
+
+They wish to express indebtedness to the authors and publishers who have
+so willingly given permission to use certain illustrations. Especially
+is this acknowledgment due to Professor John Henry Comstock, Dr. L. O.
+Howard, Dr. Graham-Smith, and Professor G. H. T. Nuttall. Professor
+Comstock not only authorized the use of departmental negatives by the
+late Professor M. V. Slingerland (credited as M. V. S.), but generously
+put at their disposal the illustrations from the MANUAL FOR THE STUDY OF
+INSECTS and from the SPIDER BOOK. Figures 5 and 111 are from Peter's
+"Der Arzt und die Heilkunst in der deutschen Vergangenheit." It should
+be noted that on examining the original, it is found that Gottfried's
+figure relates to an event antedating the typical epidemic of dancing
+mania.
+
+                                                  WM. A. RILEY.
+                                                  O. A. JOHANNSEN.
+
+  CORNELL UNIVERSITY,
+  January, 1915.
+
+
+
+
+ADDITIONS AND CORRECTIONS
+
+vi line 11, for Heilkunft read Heilkunst.
+
+18 line 2, for tarsi read tarsus.
+
+32 line 21, and legend under fig. 23, for C. (Conorhinus) abdominalis
+      read Melanolestes abdominalis.
+
+47 legend under figure for 33c read 34.
+
+92 line 22 and 25, for sangiusugus read sanguisugus.
+
+116 legend under fig. 83, for Graham-Smith read Manson.
+
+136 line 10, from bottom, insert "ring" after "chitin".
+
+137 line 3, for meditatunda read meditabunda.
+
+145 line 7, from bottom, for Rs read R_5.
+
+158 line 20, for have read has.
+
+212 after the chapter heading insert "continued".
+
+219 line 10, from bottom, for Cornohinus read Conorhinus.
+
+266 line 1, fig. 158j refers to the female.
+
+272 line 5, insert "palpus" before "and leg".
+
+281 line 6, for discodial read discoidal.
+
+281 last line, insert "from" before "the".
+
+284 line 5, for "tubercle of" read "tubercle or".
+
+305 lines 19, 28, 44, page 306 lines 1, 9, 22, 27, 30, page 307 line 7,
+      page 309 lines 8, 11, for R_{4+5} read M_{1+2}.
+
+309 legend under fig. 168 add Bureau of Entomology.
+
+312 line 36, for "near apex" read "of M_{1+2}".
+
+313 running head, for Muscidæ read Muscoidea.
+
+314 line 29, for "distal section" read "distally M_{1+2}".
+
+315 legend under fig. 172, for Pseudopyrellia read Orthellia, for
+      Lyperosia read Hæmatobia, for Umbana read urbana.
+
+323 and 325 legends under the figures, add "After Dr. J. H. Stokes".
+
+328 line 7 from bottom for Apiochæta read Aphiochæta.
+
+
+
+
+CONTENTS
+
+
+CHAPTER I
+
+INTRODUCTION                                                  1-5
+
+  Early suggestions regarding the transmission of disease by
+    insects.
+  The ways in which arthropods may affect the health of man.
+
+
+CHAPTER II
+
+ARTHROPODS WHICH ARE DIRECTLY POISONOUS                       6-56
+
+  The Araneida, or Spiders.
+    The tarantulas. Bird spiders. Spiders of the genus
+      Latrodectus. Other venomous spiders. Summary.
+  The Pedipalpida, or whip-scorpions.
+  The Scorpionida, or true scorpions.
+  The Solpugida, or solpugids.
+  The Acarina, or mites and ticks.
+  The Myriapoda, or centipedes and millipedes.
+  The Hexapoda, or true insects.
+    Piercing or biting insects poisonous to man.
+      Hemiptera, or true bugs.
+        The Notonectidæ or back-swimmers. Belostomidæ or giant
+          water-bugs. Reduviidæ, or assassin bugs. Other
+          Hemiptera reported as poisonous to man.
+      Diptera; the midges, mosquitoes and flies.
+    Stinging insects.
+      Apis mellifica, the honey bee. Other stinging forms.
+    Nettling insects.
+      Lepidoptera, or butterflies and moths. Relief from
+        poisoning by nettling larvæ.
+    Vescicating insects and those possessing other poisons
+      in their blood plasma. The blister beetles. Other
+      cryptotoxic insects.
+
+
+CHAPTER III
+
+PARASITIC ARTHROPODS AFFECTING MAN                            57-130
+
+  Acarina, or mites.
+    The Trombidiidæ, or harvest mites.
+    The Ixodoidea, or ticks.
+      Argasidæ. Ixodidæ. Treatment of tick bites.
+    The mites.
+      Dermanyssidæ. Tarsonemidæ. Sarcoptidæ, the itch mites.
+        Demodecidæ, the follicle mites.
+  Hexapoda, or true insects.
+    Siphunculata, or sucking lice.
+    Hemiptera.
+    The bed-bug. Other bed-bugs.
+  Parasitic Diptera, or flies.
+    Psychodidæ, or moth flies. Phlebotominæ. Culicidæ, or
+      mosquitoes. Simuliidæ, or black-flies. Chironomidæ, or
+      midges. Tabanidæ, or horse-flies. Leptidæ or
+      snipe-flies. Oestridæ, or bot-flies. Muscidæ, the
+      stable-fly and others.
+  Siphonaptera, or fleas.
+    The fleas affecting man, the dog, cat, and rat.
+    The true chiggers, or chigoes.
+
+CHAPTER IV
+
+ACCIDENTAL OR FACULTATIVE PARASITES                           131-143
+
+  Acarina, or mites.
+  Myriapoda, or centipedes and millipedes.
+  Lepidopterous larvæ.
+  Coleoptera, or beetles.
+  Dipterous larvæ causing myiasis.
+    Piophila casei, the cheese skipper. Chrysomyia macellaria,
+      the screw-worm fly. Calliphorinæ, the bluebottles.
+      Muscinæ, the house or typhoid fly, and others.
+      Anthomyiidæ, the lesser house-fly and others.
+      Sarcophagidæ, the flesh-flies.
+
+
+CHAPTER V
+
+ARTHROPODS AS SIMPLE CARRIERS OF DISEASE                      144-163
+
+  The house or typhoid fly as a carrier of disease.
+  Stomoxys calcitrans, the stable-fly.
+  Other arthropods which may serve as simple carriers of
+    pathogenic organisms.
+
+
+CHAPTER VI
+
+ARTHROPODS AS DIRECT INOCULATORS OF DISEASE GERMS             164-174
+
+  Some illustrations of direct inoculations of disease germs
+    by arthropods.
+  The rôle of fleas in the transmission of the plague.
+
+
+CHAPTER VII
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC ORGANISMS         175-185
+
+  Insects as intermediate hosts of tape-worms.
+  Arthropods as intermediate hosts of nematode worms.
+    Filariasis and mosquitoes.
+  Other nematode parasites of man and animals.
+
+
+CHAPTER VIII
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA          186-211
+
+  Mosquitoes and malaria.
+  Mosquitoes and yellow fever.
+
+
+CHAPTER IX
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA          212-229
+
+  Insects and trypanosomiases.
+    Fleas and lice as carriers of Trypanosoma lewisi.
+    Tsetse-flies and nagana.
+    Tsetse-flies and sleeping sickness in man.
+    South American trypanosomiasis.
+    Leishmanioses and insects.
+  Ticks and diseases of man and animals.
+    Cattle tick and Texas fever.
+    Ticks and Rocky Mountain Spotted fever of man.
+
+
+CHAPTER X
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA
+(CONTINUED)                                                   230-240
+
+  Arthropods and Spirochætoses of man and animals.
+    African relapsing fever of man.
+    European relapsing fever.
+    North African relapsing fever of man.
+    Other types of relapsing fever of man.
+    Spirochætosis of fowls.
+    Other spirochæte diseases of animals.
+  Typhus fever and lice.
+
+
+CHAPTER XI
+
+SOME POSSIBLE, BUT IMPERFECTLY KNOWN CASES OF
+ARTHROPOD TRANSMISSION OF DISEASE                             241-256
+
+  Infantile paralysis, or acute anterior poliomyelitis.
+  Pellagra. Leprosy. Verruga peruviana. Cancer.
+
+
+CHAPTER XII
+
+KEYS TO THE ARTHROPODS NOXIOUS TO MAN                         257-317
+
+  Crustacea.
+  Myriapoda, or centipedes and millipedes.
+  Arachnida (Orders of).
+    Acarina or ticks.
+  Hexapoda (Insecta).
+    Siphunculata and Hemiptera (lice and true bugs).
+    Diptera (mosquitoes, midges, and flies).
+    Siphonaptera (fleas).
+
+
+APPENDIX
+
+Hydrocyanic acid gas against household insects                318-320
+  Proportion of ingredients. A single room as an example.
+    Fumigating a large house. Precautions.
+
+Lesions produced by the bite of the black-fly                 321-326
+
+
+BIBLIOGRAPHY                                                  327-340
+
+
+INDEX                                                         341-348
+
+
+
+
+CHAPTER I.
+
+INTRODUCTION
+
+EARLY SUGGESTIONS REGARDING THE TRANSMISSION OF DISEASE BY INSECTS
+
+
+Until very recent years insects and their allies have been considered as
+of economic importance merely in so far as they are an annoyance or
+direct menace to man, or his flocks and herds, or are injurious to his
+crops. It is only within the past fifteen years that there has sprung
+into prominence the knowledge that in another and much more insiduous
+manner, they may be the enemy of mankind, that they may be among the
+most important of the disseminators of disease. In this brief period,
+such knowledge has completely revolutionized our methods of control of
+certain diseases, and has become an important weapon in the fight for
+the conservation of health.
+
+It is nowhere truer than in the case under consideration that however
+abrupt may be their coming into prominence, great movements and great
+discoveries do not arise suddenly. Centuries ago there was suggested the
+possibility that insects were concerned with the spread of disease, and
+from time to time there have appeared keen suggestions and logical
+hypotheses along this line, that lead us to marvel that the
+establishment of the truths should have been so long delayed.
+
+One of the earliest of these references is by the Italian physician,
+Mercurialis, who lived from 1530 to 1607, during a period when Europe
+was being ravaged by the dread "black death", or plague. Concerning its
+transmission he wrote: "There can be no doubt that flies feed on the
+internal secretions of the diseased and dying, then, flying away, they
+deposit their excretions on the food in neighboring dwellings, and
+persons who eat of it are thus infected."
+
+It would be difficult to formulate more clearly this aspect of the facts
+as we know them to-day, though it must always be borne in mind that we
+are prone to interpret such statements in the light of present-day
+knowledge. Mercurialis had no conception of the animate nature of
+contagion, and his statement was little more than a lucky guess.
+
+Much more worthy of consideration is the approval which was given to his
+view by the German Jesuit, Athanasius Kircher in 1658. One cannot read
+carefully his works without believing that long before Leeuwenhook's
+discovery, Kircher had seen the larger species of bacteria. Moreover, he
+attributed the production of disease to these organisms and formulated,
+vaguely, to be sure, a theory of the animate nature of contagion. It has
+taken two and a half centuries to accumulate the facts to prove his
+hypothesis.
+
+The theory of Mercurialis was not wholly lost sight of, for in the
+medical literature of the eighteenth century there are scattered
+references to flies as carriers of disease. Such a view seems even to
+have been more or less popularly accepted, in some cases. Gudger (1910),
+has pointed out that, as far back as 1769, Edward Bancroft, in "An Essay
+on the Natural History of Guiana in South America," wrote concerning the
+contagious skin-disease known as "Yaws": "It is usually believed that
+this disorder is communicated by the flies who have been feasting on a
+diseased object, to those persons who have sores, or scratches, which
+are uncovered; and from many observations, I think this is not
+improbable, as none ever receive this disorder whose skins are whole."
+
+Approaching more closely the present epoch, we find that in 1848, Dr.
+Josiah Nott, of Mobile, Alabama, published a remarkable article on the
+cause of yellow fever, in which he presented "reasons for supposing its
+specific cause to exist in some form of insect life." As a matter of
+fact, the bearing of Nott's work on present day ideas of the insect
+transmission of disease has been very curiously overrated. The common
+interpretation of his theory has been deduced from a few isolated
+sentences, but his argument appears quite differently when the entire
+article is studied. It must be remembered that he wrote at a period
+before the epoch-making discoveries of Pasteur and before the
+recognition of micro-organisms as factors in the cause of disease. His
+article is a masterly refutation of the theory of "malarial" origin of
+"all the fevers of hot climates," but he uses the term "insect" as
+applicable to the lower forms of life, and specific references to
+"mosquitoes," "aphids," "cotton-worms," and others, are merely in the
+way of similes.
+
+But, while Nott's ideas regarding the relation of insects to yellow
+fever were vague and indefinite, it was almost contemporaneously that
+the French physician, Louis Daniel Beauperthuy argued in the most
+explicit possible manner, that yellow fever and various others are
+transmitted by mosquitoes. In the light of the data which were available
+when he wrote, in 1853, it is not surprising that he erred by thinking
+that the source of the virus was decomposing matter which the mosquito
+took up and accidentally inoculated into man. Beauperthuy not only
+discussed the rôle of mosquitoes in the transmission of disease, but he
+taught, less clearly, that house-flies scatter pathogenic organisms. It
+seems that Boyce (1909) who quotes extensively from this pioneer work,
+does not go too far when he says "It is Dr. Beauperthuy whom we must
+regard as the father of the doctrine of insect-borne disease."
+
+In this connection, mention must be made of the scholarly article by the
+American physician, A. F. A. King who, in 1883, brought together an all
+but conclusive mass of argument in support of his belief that malaria
+was caused by mosquitoes. At about the same time, Finley, of Havana, was
+forcefully presenting his view that the mosquito played the chief rôle
+in the spread of yellow fever.
+
+To enter more fully into the general historical discussion is beyond the
+scope of this book. We shall have occasion to make more explicit
+references in considering various insect-borne diseases. Enough has been
+said here to emphasize that the recognition of insects as factors in the
+spread of disease was long presaged, and that there were not wanting
+keen thinkers who, with a background of present-day conceptions of the
+nature of disease, might have been in the front rank of investigators
+along these lines.
+
+
+THE WAYS IN WHICH ARTHROPODS MAY AFFECT THE HEALTH OF MAN
+
+When we consider the ways in which insects and their allies may affect
+the health of man, we find that we may treat them under three main
+groups:
+
+A. They may be directly poisonous. Such, for example, are the scorpions,
+certain spiders and mites, some of the predaceous bugs, and stinging
+insects. Even such forms as the mosquito deserve some consideration from
+this viewpoint.
+
+B. They may be parasitic, living more or less permanently on or in the
+body and deriving their sustenance from it.
+
+Of the parasitic arthropods we may distinguish, first, the _true
+parasites_, those which have adopted and become confirmed in the
+parasitic habit. Such are the itch mites, the lice, fleas, and the
+majority of the forms to be considered as parasitic.
+
+In addition to these, we may distinguish a group of _accidental_, or
+_facultative parasites_, species which are normally free-living, feeding
+on decaying substances, but which when accidentally introduced into the
+alimentary canal or other cavities of man, may exist there for a greater
+or less period. For example, certain fly larvæ, or maggots, normally
+feeding in putrifying meat, have been known to occur as accidental or
+facultative parasites in the stomach of man.
+
+C. Finally, and most important, arthropods may be transmitters and
+disseminators of disease. In this capacity they may function in one of
+three ways; as _simple carriers_, as _direct inoculators_, or as
+_essential hosts_ of disease germs.
+
+As simple carriers, they may, in a wholly incidental manner, transport
+from the diseased to the healthy, or from filth to food, pathogenic
+germs which cling to their bodies or appendages. Such, for instance, is
+the relation of the house-fly to the dissemination of typhoid.
+
+As direct inoculators, biting or piercing species may take up from a
+diseased man or animal, germs which, clinging to the mouth parts, are
+inoculated directly into the blood of the insect's next victim. It it
+thus that horse-flies may occasionally transmit anthrax. Similarly,
+species of spiders and other forms which are ordinarily perfectly
+harmless, may accidentally convey and inoculate pyogenic bacteria.
+
+It is as essential hosts of disease germs that arthropods play their
+most important rôle. In such cases an essential part of the life cycle
+of the pathogenic organism is undergone in the insect. In other words,
+without the arthropod host the disease-producing organism cannot
+complete its development. As illustrations may be cited the relation of
+the Anopheles mosquito to the malarial parasite, and the relation of the
+cattle tick to Texas fever.
+
+A little consideration will show that this is the most important of the
+group. Typhoid fever is carried by water or by contaminated milk, and in
+various other ways, as well as by the house-fly. Kill all the
+house-flies and typhoid would still exist. On the other hand, malaria is
+carried only by the mosquito, because an essential part of the
+development of the malarial parasite is undergone in this insect.
+Exterminate all of the mosquitoes of certain species and the
+dissemination of human malaria is absolutely prevented.
+
+Once an arthropod becomes an essential host for a given parasite it may
+disseminate infection in three different ways:
+
+1. By infecting man or animals who ingest it. It is thus, for example,
+that man, dog, or cat, becomes infected with the double-pored dog
+tapeworm, _Dipylidium caninum_. The cysticercoid stage occurs in the
+dog louse, or in the dog or cat fleas, and by accidentally ingesting the
+infested insect the vertebrate becomes infested. Similarly, _Hymenolepis
+diminuta_, a common tapeworm of rats and mice, and occasional in man,
+undergoes part of its life cycle in various meal-infesting insects, and
+is accidentally taken up by its definitive host. It is very probable
+that man becomes infested with _Dracunculus (Filaria) medinensis_
+through swallowing in drinking water, the crustacean, _Cyclops_,
+containing the larvæ of this worm.
+
+2. By infecting man or animals on whose skin or mucous membranes the
+insect host may be crushed or may deposit its excrement. The pathogenic
+organism may then actively penetrate, or may be inoculated by
+scratching. The causative organism of typhus fever is thus transmitted
+by the body louse.
+
+3. By direct inoculation by its bite, the insect host may transfer the
+parasite which has undergone development within it. The malarial
+parasite is thus transferred by mosquitoes; the Texas fever parasite by
+cattle ticks.
+
+
+
+
+CHAPTER II.
+
+ARTHROPODS WHICH ARE DIRECTLY POISONOUS
+
+
+Of all the myriads of insects and related forms, a very few are of
+direct use to man, some few others have forced his approbation on
+account of their wonderful beauty, but the great hordes of them are
+loathed or regarded as directly dangerous. As a matter of fact, only a
+very small number are in the slightest degree poisonous to man or to the
+higher animals. The result is that entomologists and lovers of nature,
+intent upon dissipating the foolish dread of insects, are sometimes
+inclined to go to the extreme of discrediting all statements of serious
+injury from the bites or stings of any species.
+
+Nevertheless, it must not be overlooked that poisonous forms do exist,
+and they must receive attention in a consideration of the ways in which
+arthropods may affect the health of man. Moreover, it must be recognized
+that "what is one man's meat, is another man's poison," and that in
+considering the possibilities of injury we must not ignore individual
+idiosyncrasies. Just as certain individuals may be poisoned by what, for
+others, are common articles of food, so some persons may be abnormally
+susceptible to insect poison. Thus, the poison of a bee sting may be of
+varying severity, but there are individuals who are made seriously sick
+by a single sting, regardless of the point of entry. Some individuals
+scarcely notice a mosquito bite, others find it very painful, and so
+illustrations of this difference in individuals might be multiplied.
+
+In considering the poisonous arthropods, we shall take them up by
+groups. The reader who is unacquainted with the systematic relationship
+of insects and their allies is referred to Chapter XII. No attempt will
+be made to make the lists under the various headings exhaustive, but
+typical forms will be discussed.
+
+
+ARANEIDA OR SPIDERS
+
+Of all the arthropods there are none which are more universally feared
+than are the spiders. It is commonly supposed that the majority, if not
+all the species are poisonous and that they are aggressive enemies of
+man and the higher animals, as well as of lower forms.
+
+That they really secrete a poison may be readily inferred from the
+effect of their bite upon insects and other small forms. Moreover, the
+presence of definite and well-developed poison glands can easily be
+shown. They occur as a pair of pouches (fig. 1) lying within the
+cephalothorax and connected by a delicate duct with a pore on the claw
+of the chelicera, or so-called "mandible" on the convex surface of the
+claw in such a position that it is not plugged and closed by the flesh
+of the victim.
+
+[Illustration: 1. Head of a spider showing poison gland (_c_) and its
+relation to the chelicera (_a_).]
+
+The glands may be demonstrated by slowly and carefully twisting off a
+chelicera and pushing aside the stumps of muscles at its base. By
+exercising care, the chitinous wall of the chelicera and its claw may be
+broken away and the duct traced from the gland to its outlet. The inner
+lining of the sac is constituted by a highly developed glandular
+epithelium, supported by a basement membrane of connective tissue and
+covered by a muscular layer, (fig. 2). The muscles, which are striated,
+are spirally arranged (fig. 1), and are doubtless under control of the
+spider, so that the amount of poison to be injected into a wound may be
+varied.
+
+[Illustration: 2. Section through a venom gland of Latrodectus
+13-guttatus showing the peritoneal, muscular and epithelial layers.
+After Bordas.]
+
+The poison itself, according to Kobert (1901), is a clear, colorless
+fluid, of oily consistency, acid reaction, and very bitter taste. After
+the spider has bitten two or three times, its supply is exhausted and
+therefore, as in the case of snakes, the poison of the bite decreases
+quickly with use, until it is null. To what extent the content of the
+poison sacs may contain blood serum or, at least, active principles of
+serum, in addition to a specific poison formed by the poison glands
+themselves, Kobert regards as an open question. He believes that the
+acid part of the poison, if really present, is formed by the glands and
+that, in the case of some spiders, the ferment-like, or better, active
+toxine, comes from the blood.
+
+[Illustration: 3. Chelicera of a spider.]
+
+But there is a wide difference between a poison which may kill an insect
+and one which is harmful to men. Certain it is that there is no lack of
+popular belief and newspaper records of fatal cases, but the evidence
+regarding the possibility of fatal or even very serious results for man
+is most contradictory. For some years, we have attempted to trace the
+more circumstantial newspaper accounts, which have come to our notice,
+of injury by North American species. The results have served, mainly, to
+emphasize the straits to which reporters are sometimes driven when there
+is a dearth of news. The accounts are usually vague and lacking in any
+definite clue for locating the supposed victim. In the comparatively few
+cases where the patient, or his physician, could be located, there was
+either no claim that the injury was due to spider venom, or there was no
+evidence to support the belief. Rarely, there was evidence that a
+secondary blood poisoning, such as might be brought about by the prick
+of a pin, or by any mechanical injury, had followed the bite of a
+spider. Such instances have no bearing on the question of the venomous
+nature of these forms.
+
+[Illustration: 4. The Italian tarantula (Lycosa tarantula). After
+Kobert.]
+
+The extreme to which unreasonable fear of the bites of spiders
+influenced the popular mind was evidenced by the accepted explanation of
+the remarkable dancing mania, or tarantism, of Italy during the Middle
+Ages. This was a nervous disorder, supposed to be due to the bite of a
+spider, the European tarantula (fig. 4), though it was also, at times,
+attributed to the bite of the scorpion. In its typical form, it was
+characterized by so great a sensibility to music that under its
+influence the victims indulged in the wildest and most frenzied dancing,
+until they sank to the ground utterly exhausted and almost lifeless. The
+profuse perspiring resulting from these exertions was supposed to be the
+only efficacious remedy for the disease. Certain forms of music were
+regarded as of especial value in treating this tarantism, and hence the
+name of "tarantella" was applied to them. Our frontispiece, taken from
+Athanasius Kircher's _Magnes sive de Arte Magnetica_, 1643 ed.,
+represents the most commonly implicated spider and illustrates some of
+what Fabre has aptly designated as "medical choreography."
+
+The disease was, in reality, a form of hysteria, spreading by sympathy
+until whole communities were involved, and was paralleled by the
+outbreaks of the so-called St. Vitus's or St. John's dance, which swept
+Germany at about the same time (fig. 5). The evidence that the spider
+was the cause of the first is about as conclusive as is that of the
+demoniacal origin of the latter. The true explanation of the outbreaks
+is doubtless to be found in the depleted physical and mental condition
+of the people, resulting from the wars and the frightful plagues which
+devastated all Europe previous to, and during these times. An
+interesting discussion of these aspects of the question is to be found
+in Hecker.
+
+[Illustration: 5. Dancing mania. Illustration from Johann Ludwig
+Gottfried's Chronik. 1632.]
+
+So gross has been the exaggeration and so baseless the popular fear
+regarding spiders that entomologists have been inclined to discredit all
+accounts of serious injury from their bites. Not only have the most
+circumstantial of newspaper accounts proved to be without foundation but
+there are on record a number of cases where the bite of many of the
+commoner species have been intentionally provoked and where the effect
+has been insignificant. Some years ago the senior author personally
+experimented with a number of the largest of our northern species, and
+with unexpected results. The first surprise was that the spiders were
+very unwilling to bite and that it required a considerable effort to get
+them to attempt to do so. In the second place, most of those
+experimented with were unable to pierce the skin of the palm or the back
+of the hand, but had to be applied to the thin skin between the fingers
+before they were able to draw blood. Unfortunately, no special attempt
+was made to determine, at the time, the species experimented with, but
+among them were _Theridion tepidariorum_, _Miranda aurantia_
+(_Argiopa_), _Metargiope trifasciata_, _Marxia stellata_, _Aranea
+trifolium_, _Misumena vatia_, and _Agelena nævia_. In no case was the
+bite more severe than a pin prick and though in some cases the sensation
+seemed to last longer, it was probably due to the fact that the mind was
+intent upon the experiment.
+
+[Illustration: 6. An American tarantula (Eurypelma hentzii). Natural
+size. After Comstock.]
+
+Similar experiments were carried out by Blackwell (1855), who believed
+that in the case of insects bitten, death did not result any more
+promptly than it would have from a purely mechanical injury of equal
+extent. He was inclined to regard all accounts of serious injury to man
+as baseless. The question cannot be so summarily dismissed, and we shall
+now consider some of the groups which have been more explicitly
+implicated.
+
+
+THE TARANTULAS.--In popular usage, the term "tarantula" is loosely
+applied to any one of a number of large spiders. The famous tarantulas
+of southern Europe, whose bites were supposed to cause the dancing
+mania, were Lycosidæ, or wolf-spiders. Though various species of this
+group were doubtless so designated, the one which seems to have been
+most implicated was _Lycosa tarantula_ (L.), (fig. 4). On the other
+hand, in this country, though there are many Lycosidæ, the term
+"tarantula" has been applied to members of the superfamily Avicularoidea
+(fig. 6), including the bird-spiders.
+
+Of the Old World Lycosidæ there is no doubt that several species were
+implicated as the supposed cause of the tarantism. In fact, as we have
+already noted, the blame was sometimes attached to a scorpion. However,
+there seems to be no doubt that most of the accounts refer to the spider
+known as _Lycosa tarantula_.
+
+There is no need to enter into further details here regarding the
+supposed virulence of these forms, popular and the older medical
+literature abound in circumstantial accounts of the terrible effects of
+the bite. Fortunately, there is direct experimental evidence which bears
+on the question.
+
+Fabre induced a common south European wolf-spider, _Lycosa narbonensis_,
+to bite the leg of a young sparrow, ready to leave the nest. The leg
+seemed paralyzed as a result of the bite, and though the bird seemed
+lively and clamored for food the next day, on the third day it died. A
+mole, bitten on the nose, succumbed after thirty-six hours. From these
+experiments Fabre seemed justified in his conclusion that the bite of
+this spider is not an accident which man can afford to treat lightly.
+Unfortunately, there is nothing in the experiments, or in the symptoms
+detailed, to exclude the probability that the death of the animals was
+the result of secondary infection.
+
+As far back as 1693, as we learn from the valuable account of Kobert,
+(1901), the Italian physician, Sanguinetti allowed himself to be bitten
+on the arm by two tarantulas, in the presence of witnesses. The
+sensation was equivalent to that from an ant or a mosquito bite and
+there were no other phenomena the first day. On the second day the wound
+was inflamed and there was slight ulceration. It is clear that these
+later symptoms were due to a secondary infection. These experiments have
+been repeated by various observers, among whom may be mentioned Leon
+Dufour, Josef Erker and Heinzel, and with the similar conclusion that
+the bite of the Italian tarantula ordinarily causes no severe symptoms.
+In this conclusion, Kobert, though firmly convinced of the poisonous
+nature of some spiders, coincides. He also believes that striking
+symptoms may be simulated or artificially induced by patients in order
+to attract interest, or because they have been assured that the bite,
+under all circumstances, caused tarantism.
+
+The so-called Russian tarantula, _Trochosa singoriensis_ (fig. 7), is
+much larger than the Italian species, and is much feared. Kobert carried
+out a series of careful experiments with this species and his results
+have such an important bearing on the question of the venomous nature of
+the tarantula that we quote his summary. Experimenting first on nearly a
+hundred living specimens of _Trochosa singoriensis_ from Crimea he says
+that:
+
+"The tarantulas, no matter how often they were placed on the skin,
+handled, and irritated, could not be induced to bite either myself, the
+janitor, or the ordinary experimental animals. The objection that the
+tarantulas were weak and indifferent cannot stand, for as soon as I
+placed two of them on the shaved skin of a rabbit, instead of an attack
+on the animal, there began a furious battle between the two spiders,
+which did not cease until one of the two was killed."
+
+[Illustration: 7. Trochosa singoriensis. After Kobert.]
+
+"Since the spiders would not bite, I carefully ground up the fresh
+animals in physiological salt solution, preparing an extract which must
+have contained, in solution, all of the poisonous substance of their
+bodies. While in the case of _Latrodectus_, as we shall see, less than
+one specimen sufficed to yield an active extract, I have injected the
+filtered extract of six fresh Russian tarantulas, of which each one was
+much heavier than an average _Latrodectus_, subcutaneously and into the
+jugular vein of various cats without the animals dying or showing any
+special symptoms. On the basis of my experiments I can therefore only
+say that the quantity of the poison soluble in physiological salt
+solution, even when the spiders are perfectly fresh and well nourished,
+is very insignificant. That the poison of the Russian tarantula is not
+soluble in physiological salt solution, is exceedingly improbable.
+Moreover, I have prepared alcoholic extracts and was unable to find them
+active. Since the Russian spider exceeds the Italian in size and in
+intensity of the bite, it seems very improbable to me that the
+pharmacological test of the Italian tarantula would yield essentially
+other results than those from the Russian species."
+
+To the AVICULAROIDEA belong the largest and most formidable appearing of
+the spiders and it is not strange that in the New World they have fallen
+heir to the bad reputation, as well as to the name of the tarantula of
+Europe. In this country they occur only in the South or in the far West,
+but occasionally living specimens are brought to our northern ports in
+shipments of bananas and other tropical produce, and are the source of
+much alarm. It should be mentioned, however, that the large spider most
+frequently found under such circumstances is not a tarantula at all, but
+one of the Heteropodidæ, or giant crab-spiders, (fig. 8).
+
+[Illustration: 8. The giant crab-spider or banana spider (Heteropoda
+venatoria). Natural size. After Comstock.]
+
+In spite of their prominence and the fear which they arouse there are
+few accurate data regarding these American tarantulas. It has often been
+shown experimentally that they can kill small birds and mammals, though
+it is doubtful if these form the normal prey of any of the species, as
+has been claimed. There is no question but that the mere mechanical
+injury which they may inflict, and the consequent chances of secondary
+infection, justify, in part, their bad reputation. In addition to the
+injury from their bite, it is claimed that the body hairs of several of
+the South American species are readily detached and are urticating.
+
+Recently, Phisalix (1912) has made a study of the physiological effects
+of the venom of two Avicularoidea, _Phormictopus carcerides_ Pocock,
+from Haiti and _Cteniza sauvagei_ Rossi, from Corsica. The glands were
+removed aseptically and ground up with fine, sterilized sand in
+distilled water. The resultant liquid was somewhat viscid, colorless,
+and feebly alkaline. Injected into sparrows and mice the extract of
+_Phormictopus_ proved very actively poisonous, that from a single spider
+being sufficient to kill ten sparrows or twenty mice. It manifested
+itself first and, above all, as a narcotic, slightly lowering the
+temperature and paralyzing the respiration. Muscular and cardiac
+weakening, loss of general sensibility, and the disappearance of
+reflexes did not occur until near the end. The extract from _Cteniza_
+was less active and, curiously enough, the comparative effect on
+sparrows and on mice was just reversed.
+
+
+SPIDERS OF THE GENUS LATRODECTUS.--While most of the popular accounts of
+evil effects from the bites of spiders will not stand investigation, it
+is a significant fact that, the world over, the best authenticated
+records refer to a group of small and comparatively insignificant
+spiders belonging to the genus _Latrodectus_, of the family Theridiidæ.
+The dread "Malmigniatte" of Corsica and South Europe, the "Karakurte" of
+southeastern Russia, the "Katipo" of New Zealand, the "Mena-vodi" and
+"Vancoho" of Madagascar, and our own _Latrodectus mactans_, all belong
+to this genus, and concerning all of these the most circumstantial
+accounts of their venomous nature are given. These accounts are not mere
+fantastic stories by uneducated natives but in many cases are reports
+from thoroughly trained medical men.
+
+The symptoms produced are general, rather than local. As summarized by
+Kobert (1901) from a study of twenty-two cases treated in 1888, in the
+Kherson (Russia) Government Hospital and Berislaw (Kherson) District
+Hospital the typical case, aside from complications, exhibits the
+following symptoms. The victim suddenly feels the bite, like the sting
+of a bee. Swelling of the barely reddened spot seldom follows. The
+shooting pains, which quickly set in, are not manifested at the point of
+injury but localized at the joints of the lower limb and in the region
+of the hip. The severity of the pain forces the victim to the hospital,
+in spite of the fact that they otherwise have a great abhorrence of it.
+The patient is unable to reach the hospital afoot, or, at least, not
+without help, for there is usually inability to walk. The patient, even
+if he has ridden, reaches the hospital covered with cold sweat and
+continues to perspire for a considerable period. His expression
+indicates great suffering. The respiration may be somewhat dyspnoeic,
+and a feeling of oppression in the region of the heart is common. There
+is great aversion to solid food, but increasing thirst for milk and tea.
+Retention of urine, and constipation occur. Cathartics and, at night,
+strong narcotics are desired. Warm baths give great relief. After three
+days, there is marked improvement and usually the patient is dismissed
+after the fifth. This summary of symptoms agrees well with other
+trustworthy records.
+
+It would seem, then, that Riley and Howard (1889), who discussed a
+number of accounts in the entomological literature, were fully justified
+in their statement that "It must be admitted that certain spiders of the
+genus _Latrodectus_ have the power to inflict poisonous bites, which may
+(probably exceptionally and depending upon exceptional conditions) bring
+about the death of a human being."
+
+And yet, until recently the evidence bearing on the question has been
+most conflicting. The eminent arachnologist, Lucas, (1843) states that
+he himself, had been repeatedly bitten by the Malmigniatte without any
+bad effects. Dr. Marx, in 1890, gave before the Entomological Society of
+Washington, an account of a series of experiments to determine whether
+the bite of _Latrodectus mactans_ is poisonous or not. He described the
+poison glands as remarkably small[A] and stated that he had introduced
+the poison in various ways into guinea-pigs and rabbits without
+obtaining any satisfactory results. Obviously, carefully conducted
+experiments with the supposed venom were needed and fortunately they
+have been carried out in the greatest detail by Kobert (1901).
+
+This investigator pointed out that there were two factors which might
+account for the discrepancies in the earlier experiments. In the first
+place, the poison of spiders, as of snakes, might be so exhausted after
+two or three bites that further bites, following directly, might be
+without visible effect. Secondly, the application of the poison by means
+of the bite, is exceedingly inexact, since even after the most careful
+selection of the point of application, the poison might in one instance
+enter a little vein or lymph vessel, and in another case fail to do so.
+Besides, there would always remain an incalculable and very large amount
+externally, in the nonabsorptive epithelium. While all of these factors
+enter into the question of the effect of the bite in specific instances,
+they must be as nearly as possible obviated in considering the question
+of whether the spiders really secrete a venom harmful to man.
+
+Kobert therefore sought to prepare extracts which would contain the
+active principles of the poison and which could be injected in definite
+quantities directly into the blood of the experimental animal. For this
+purpose various parts of the spiders were rubbed up in a mortar with
+distilled water, or physiological salt solution, allowed to stand for an
+hour, filtered, and then carefully washed, by adding water drop by drop
+for twenty-four hours. The filtrate and the wash-water were then united,
+well mixed and, if necessary, cleared by centrifuging or by exposure to
+cold. The mixture was again filtered, measured, and used, in part, for
+injection and, in part, for the determination of the organic materials.
+
+Such an extract was prepared from the cephalothoraces of eight dried
+specimens of the Russian _Latrodectus_ and three cubic centimeters of
+this, containing 4.29 mg. of organic material, were injected into the
+jugular vein of a cat weighing 2450 grams. The previously very active
+animal was paralyzed and lay in whatever position it was placed. The
+sensibility of the skin of the extremities and the rump was so reduced
+that there was no reaction from cutting or sticking. There quickly
+followed dyspnoea, convulsions, paralysis of the respiratory muscles
+and of the heart. In twenty-eight minutes the cat was dead, after having
+exhibited exactly the symptoms observed in severe cases of poisoning of
+man from the bite of this spider.
+
+These experiments were continued on cats, dogs, guinea pigs and various
+other animals. Not only extracts from the cephalothorax, but from other
+parts of the body, from newly hatched spiders, and from the eggs were
+used and all showed a similar virulence. Every effort was made to avoid
+sources of error and the experiments, conducted by such a recognized
+authority in the field of toxicology, must be accepted as conclusively
+showing that this spider and, presumably, other species of the genus
+_Latrodectus_ against which the clinical evidence is quite parallel,
+possess a poison which paralyzes the heart and central nervous system,
+with or without preliminary stimulus of the motor center. If the
+quantity of the poison which comes into direct contact with the blood is
+large, there may occur hæmolysis and thrombosis of the vessels.
+
+On the other hand, check experiments were carried out, using similar
+extracts of many common European spiders of the genera _Tegenaria_,
+_Drassus_, _Agelena_, _Eucharia_ and _Argyroneta_, as well as the
+Russian tarantula, _Lycosa singoriensis_. In no other case was the
+effect on experimental animals comparable to the _Latrodectus_ extract.
+
+Kobert concludes that in its chemical nature the poison is neither an
+alkaloid, nor a glycoside, nor an acid, but a toxalbumen, or poisonous
+enzyme which is very similar to certain other animal poisons, notably
+that of the scorpion.
+
+[Illustration: 9. Latrodectus mactans; (_a_) female, x 3; (_b_) venter
+of female; (_c_) dorsum of male. After Comstock.]
+
+The genus _Latrodectus_ is represented in the United States by at least
+two species, _L. mactans_ and _L. geometricus_. Concerning _L. mactans_
+there are very circumstantial accounts of serious injury and even death
+in man[B]. _Latrodectus mactans_ is coal black, marked with red or
+yellow or both. It has eight eyes, which are dissimilar in color and
+are distinctly in front of the middle of the thorax, the lateral eyes of
+each side widely separate. The tarsus of the fourth pair of legs has a
+number of curved setæ in a single series. It has on the ventral side of
+its abdomen an hour-glass shaped spot. The full-grown female is about
+half an inch in length. Its globose abdomen is usually marked with one
+or more red spots dorsally along the middle line. The male is about half
+as long but has in addition to the dorsal spots, four pairs of stripes
+along the sides. Immature females resemble the male in coloring (fig.
+9).
+
+Regarding the distribution of _Latrodectus mactans_, Comstock states
+that: "Although it is essentially a Southern species, it occurs in
+Indiana, Ohio, Pennsylvania, New Hampshire, and doubtless other of the
+Northern States." _L. geometricus_ has been reported from California.
+
+
+OTHER VENOMOUS SPIDERS--While conclusive evidence regarding the venomous
+nature of spiders is meager and relates almost wholly to that of the
+genus _Latrodectus_, the group is a large one and we are not justified
+in dismissing arbitrarily, all accounts of injury from their bites.
+Several species stand out as especially needing more detailed
+investigation.
+
+_Chiracanthium nutrix_ is a common European species of the family
+Clubionidæ, concerning which there is much conflicting testimony. Among
+the reports are two by distinguished scientists whose accounts of
+personal experiences cannot be ignored. A. Forel allowed a spider of
+this species to bite him and not only was the pain extreme, but the
+general symptoms were so severe that he had to be helped to his house.
+The distinguished arachnologist, Bertkau reports that he, himself, was
+bitten and that an extreme, burning pain spread almost instantaneously
+over the arm and into the breast. There were slight chills the same day
+and throbbing pain at the wound lasted for days. While this particular
+species is not found in the United States, there are two other
+representatives of the genus and it is possible that they possess the
+same properties. We are unaware of any direct experimental work on the
+poison.
+
+_Epeira diadema_, of Europe, belongs to a wholly different group, that
+of the orb-weavers, but has long been reputed venomous. Kobert was able
+to prepare from it an extract whose effects were very similar to that
+prepared from _Latrodectus_, though feebler in its action. Under
+ordinary circumstances this spider is unable to pierce the skin of man
+and though Kobert's results seem conclusive, the spider is little to be
+feared.
+
+_Phidippus audax_ (_P. tripunctatus_) is one of our largest Attids, or
+jumping spiders. The late Dr. O. Lugger describes a case of severe
+poisoning from the bite of this spider and though details are lacking,
+it is quite possible that this and other large species of the same
+group, which stalk their prey, may possess a more active poison than
+that of web-building species.
+
+
+SUMMARY--It is clearly established that our common spiders are not to be
+feared and that the stories regarding their virulence are almost wholly
+without foundation. On the other hand, the chances of secondary
+infection from the bites of some of the more powerful species are not to
+be ignored.
+
+Probably all species possess a toxin secreted by the poison gland,
+virulent for insects and other normal prey of the spiders, but with
+little or no effect on man.
+
+There are a very few species, notably of the genus _Latrodectus_, and
+possibly including the European _Chiracanthium nutrix_ and _Epeira
+diadema_, which possess, in addition, a toxalbumen derived from the
+general body tissue, which is of great virulence and may even cause
+death in man and the higher animals.
+
+[Illustration: 10. A whip-scorpion (Mastigoproctus giganteus). Half
+natural size. After Comstock.]
+
+
+THE PEDIPALPIDA OR WHIP-SCORPIONS
+
+The tailed whip-scorpions, belonging to the family Thelyphonidæ, are
+represented in the United States by the giant whip-scorpion
+_Mastigoproctus giganteus_ (fig. 10), which is common in Florida, Texas
+and some other parts of the South. In Florida, it is locally known as
+the "grampus" or "mule-killer" and is very greatly feared. There is no
+evidence that these fears have any foundation, and Dr. Marx states that
+there is neither a poison gland nor a pore in the claw of the
+chelicera.
+
+
+THE SCORPIONIDA, OR TRUE SCORPIONS
+
+The true scorpions are widely distributed throughout warm countries and
+everywhere bear an evil reputation. According to Comstock (1912), about
+a score of species occur in the Southern United States. These are
+comparatively small forms but in the tropics members of this group may
+reach a length of seven or eight inches. They are pre-eminently
+predaceous forms, which lie hidden during the day and seek their prey by
+night.
+
+[Illustration: 11. A true scorpion. After Comstock.]
+
+The scorpions (fig. 11) possess large pedipalpi, terminated by strongly
+developed claws, or chelæ. They may be distinguished from all other
+Arachnids by the fact that the distinctly segmented abdomen is divided
+into a broad basal region of seven segments and a terminal, slender,
+tail-like division of five distinct segments.
+
+The last segment of the abdomen, or telson, terminates in a
+ventrally-directed, sharp spine, and contains a pair of highly developed
+poison glands. These glands open by two small pores near the tip of the
+spine. Most of the species when running carry the tip of the abdomen
+bent upward over the back, and the prey, caught and held by the
+pedipalpi, is stung by inserting the spine of the telson and allowing it
+to remain for a time in the wound.
+
+The glands themselves have been studied in _Prionurus citrinus_ by
+Wilson (1904). He found that each gland is covered by a sheet of muscle
+on its mesal and dorsal aspects, which may be described as the
+_compressor muscle_. The muscle of each side is inserted by its edge
+along the ventral inner surface of the chitinous wall of the telson,
+close to the middle line, and by a broader insertion laterally. A layer
+of fine connective tissue completely envelops each gland and forms the
+basis upon which the secreting cells rest. The secreting epithelium is
+columnar; and apparently of three different types of cells.
+
+1. The most numerous have the appearance of mucous cells, resembling the
+goblet cells of columnar mucous membranes. The nucleus, surrounded by a
+small quantity of protoplasm staining with hæmatoxylin, lies close to
+the base of the cell.
+
+2. Cells present in considerable numbers, the peripheral portions of
+which are filled with very numerous fine granules, staining with acid
+dyes such as methyl orange.
+
+3. Cells few in number, filled with very large granules, or irregular
+masses of a substance staining with hæmatoxylin.
+
+The poison, according to Kobert (1893), is a limpid, acid-reacting
+fluid, soluble in water but insoluble in absolute alcohol and ether.
+There are few data relative to its chemical nature. Wilson (1901) states
+that a common Egyptian species, _Buthus quinquestriatus_, has a specific
+gravity of 1.092, and contains 20.3% of solids and 8.4% ash.
+
+The venom of different species appears to differ not only quantitatively
+but qualitatively. The effects of the bite of the smaller species of the
+Southern United States may be painful but there is no satisfactory
+evidence that it is ever fatal. On the other hand, certain tropical
+species are exceedingly virulent and cases of death of man from the bite
+are common.
+
+In the case of _Buthus quinquestriatus_, Wilson (1904) found the
+symptoms in animals to be hypersecretion, salivation and lachrymation,
+especially marked, convulsions followed by prolonged muscular spasm;
+death from asphyxia. The temperature shows a slight, rarely
+considerable, rise. Rapid and considerable increase of blood-pressure
+(observed in dogs) is followed by a gradual fall with slowing of the
+heart-beat. The coagulability of the blood is not affected.
+
+An interesting phase of Wilson's work was the experiments on desert
+mammals. The condition under which these animals exist must frequently
+bring them in contact with scorpions, and he found that they possess a
+degree of immunity to the venom sufficient at least to protect them from
+the fatal effects of the sting.
+
+As far as concerns its effect on man, Wilson found that much depended
+upon the age. As high as 60 per cent of the cases of children under
+five, resulted fatally. Caroroz (1865), states that in a Mexican state
+of 15,000 inhabitants, the scorpions were so abundant and so much feared
+that the authorities offered a bounty for their destruction. A result
+was a large number of fatalities, over two hundred per year. Most of the
+victims were children who had attempted to collect the scorpions.
+
+The treatment usually employed in the case of bites by the more
+poisonous forms is similar to that for the bite of venomous snakes.
+First, a tight ligature is applied above the wound so as to stop the
+flow of blood and lymph from that region. The wound is then freely
+excised and treated with a strong solution of permanganate of potash, or
+with lead and opium lotion.
+
+In recent years there have been many attempts to prepare an antivenom,
+or antiserum comparable to what has been used so effectively in the case
+of snake bites. The most promising of these is that of Todd (1909),
+produced by the immunization of suitable animals. This antivenom proved
+capable of neutralizing the venom when mixed _in vitro_ and also acts
+both prophylactically and curatively in animals. Employed curatively in
+man, it appears to have a very marked effect on the intense pain
+following the sting, and the evidence so far indicates that its prompt
+use greatly reduces the chance of fatal results.
+
+
+THE SOLPUGIDA, OR SOLPUGIDS
+
+The SOLPUGIDA are peculiar spider-like forms which are distinguished
+from nearly all other arachnids by the fact that they possess no true
+cephalothorax, the last two leg-bearing segments being distinct,
+resembling those of the abdomen in this respect. The first pair of legs
+is not used in locomotion but seemingly functions as a second pair of
+pedipalpi. Figure 12 illustrates the striking peculiarities of the
+group. They are primarily desert forms and occur in the warm zones of
+all countries. Of the two hundred or more species, Comstock lists twelve
+as occurring in our fauna. These occur primarily in the southwest.
+
+[Illustration: 12. A solpugid (Eremobates cinerea). After Comstock.]
+
+The Solpugida have long borne a bad reputation and, regarding virulence,
+have been classed with the scorpions. Among the effects of their bites
+have been described painful swelling, gangrene, loss of speech, cramps,
+delirium, unconsciousness and even death. Opposed to the numerous loose
+accounts of poisoning, there are a number of careful records by
+physicians and zoölogists which indicate clearly that the effects are
+local and though they may be severe, they show not the slightest symptom
+of direct poisoning.
+
+More important in the consideration of the question is the fact that
+there are neither poison glands nor pores in the fangs for the exit of
+any poisonous secretion. This is the testimony of a number of prominent
+zoölogists, among whom is Dr. A. Walter, who wrote to Kobert at length
+on the subject and whose conclusions are presented by him.
+
+However, it should be noted that the fangs are very powerful and are
+used in such a manner that they may inflict especially severe wounds.
+Thus, there may be more opportunity for secondary infection than is
+usual in the case of insect wounds.
+
+The treatment of the bite of the Solpugida is, therefore, a matter of
+preventing infection. The wound should be allowed to bleed freely and
+then washed out with a 1:3000 solution of corrosive sublimate, and, if
+severe, a wet dressing of this should be applied. If infection takes
+place, it should be treated in the usual manner, regardless of its
+origin.
+
+
+THE ACARINA, OR MITES AND TICKS
+
+A number of the parasitic Acarina evidently secrete a specific poison,
+presumably carried by the saliva, but in most cases its effect on man is
+insignificant. There is an abundant literature dealing with the
+poisonous effect of the bite of these forms, especially the ticks, but
+until recently it has been confused by failure to recognize that various
+species may transmit diseases of man, rather than produce injury through
+direct poisoning. We shall therefore discuss the Acarina more especially
+in subsequent chapters, dealing with parasitism and with disease
+transmission.
+
+Nevertheless, after the evidence is sifted, there can be no doubt that
+the bites of certain ticks may occasionally be followed by a direct
+poisoning, which may be either local or general in its effects. Nuttall
+(1908) was unable to determine the cause of the toxic effect, for, in
+_Argas persicus_, the species most often implicated, he failed to get
+the slightest local or general effect on experimental animals, from the
+injection of an emulsion prepared by crushing three of the ticks.
+
+It seems clearly established that the bite of certain ticks may cause a
+temporary paralysis, or even complete paralysis, involving the organs of
+respiration or the heart, and causing death. In 1912, Dr. I. U. Temple,
+of Pendleton, Oregon, reported several cases of what he called "acute
+ascending paralysis" associated with the occurrence of ticks on the head
+or the back of the neck. A typical severe case was that of a six year
+old child, who had retired in her usual normal health. The following
+morning upon arising she was unable to stand on her feet. She exhibited
+paralysis extending to the knees, slight temperature, no pain, sensory
+nerves normal, motor nerves completely paralyzed, reflexes absent. The
+following day the paralysis had extended to the upper limbs, and before
+night of the third day the nerves of the throat (hypoglossal) were
+affected. The thorax and larynx were involved, breathing was labored,
+she was unable to swallow liquids, phonation was impossible and she
+could only make low, guttural sounds. At this stage, two ticks, fully
+distended with blood, were found over the junction of the spinal column
+with the occipital bones in the hollow depression. They were removed by
+the application of undiluted creoline. Though the child's life was
+despaired of, by the following morning she was very much improved. By
+evening she was able to speak. The paralysis gradually receded,
+remaining longest in the feet, and at the end of one week the patient
+was able to go home.
+
+There was some doubt as to the exact species of tick implicated in the
+cases which Dr. Temple reported, although the evidence pointed strongly
+to _Dermacentor venustus_.[C] Somewhat later, Hadwen (1913) reported
+that "tick paralysis" occurs in British Columbia, where it affects not
+only man, but sheep and probably other animals. It is caused by the
+bites of _Dermacentor venustus_ and was experimentally produced in lambs
+and a dog (Hadwen and Nuttall, 1913). It is only when the tick begins to
+engorge or feed rapidly, some days after it has become attached, that
+its saliva produces pathogenic effects.
+
+Ulceration following tick bite is not uncommon. In many of the instances
+it is due to the file-like hypostome, with its recurved teeth, being
+left in the wound when the tick is forcibly pulled off.
+
+
+THE MYRIAPODA, OR CENTIPEDES AND MILLIPEDES
+
+The old class, Myriapoda includes the DIPLOPODA, or millipedes, and the
+CHILOPODA, or centipedes. The present tendency is to raise these groups
+to the rank of classes.
+
+
+The Diplopoda
+
+The DIPLOPODA, or millipedes (fig. 13), are characterized by the
+presence of two pairs of legs to a segment. The largest of our local
+myriapods belong to this group. They live in moist places, feeding
+primarily on decaying vegetable matter, though a few species
+occasionally attack growing plants.
+
+[Illustration: 13. A millipede. After Comstock.]
+
+The millipedes are inoffensive and harmless. _Julus terrestris_, and
+related species, when irritated pour out over the entire body a
+yellowish secretion which escapes from cutaneous glands. It is volatile,
+with a pungent odor, and Phisalix (1900) has shown that it is an active
+poison when injected into the blood of experimental animals. This,
+however, does not entitle them to be considered as poisonous arthropods,
+in the sense of this chapter, any more than the toad can be considered
+poisonous to man because it secretes a venom from its cutaneous glands.
+
+
+The Chilopoda
+
+[Illustration: 14. Two common centipedes.
+
+(_a_) Lithobius forficatus. After Comstock.
+
+(_b_) Scutigera forceps. Natural size; after Howard.]
+
+The CHILOPODA, or centipedes (fig. 14), unlike the millipedes, are
+predaceous forms, and possess well developed poison glands for killing
+their prey. These glands are at the base of the first pair of legs
+(fig. 15), which are bent forward so as to be used in holding their
+prey. The legs terminate in a powerful claw, at the tip of which is the
+outlet of the poison glands.
+
+The poison is a limpid, homogeneous, slightly acid fluid, which
+precipitates in distilled water. Briot (1904) extracted it from the
+glands of _Scolopendra morsitans_, a species common in central France,
+and found that it was actively venomous for the ordinary experimental
+animals. A rabbit of two kilograms weight received an injection of three
+cubic centimeters in the vein of the ear and died in a minute. A white
+rat, weighing forty-eight grams, received one and a half cubic
+centimeters in the hind leg. There was an almost immediate paralysis of
+the leg and marked necrosis of the tissues.
+
+[Illustration: 15. Mandible of Scolopendra cingulata showing venom
+gland. After Dubosq.]
+
+As for the effect on man, there is little foundation for the fear with
+which centipedes are regarded. Our native species produce, at most,
+local symptoms,--sometimes severe local pain and swelling,--but there is
+no authentic record of fatal results. In the tropics, some of the
+species attain a large size, _Scolopendra gigantea_ reaching a length of
+nearly a foot. These forms are justly feared, and there is good evidence
+that death sometimes, though rarely, results from their bite.
+
+One of the most careful accounts of death from the sting of the scorpion
+is that of Linnell, (1914), which relates to a comparatively small
+Malayan species, unfortunately undetermined. The patient, a coolie, aged
+twenty, was admitted to a hospital after having been stung two days
+previously on the left heel. For cure, the other coolies had made him
+eat the head of the scorpion. On admission, the patient complained of
+"things creeping all over the body". Temp. 102.8°. On the fourth day he
+had paralysis of the legs, and on the fifth day motor paralysis to the
+umbilicus, sensation being unaltered. On the sixth day there was
+retention of the urine and on the ninth day (first test after third day)
+sugar was present. On the thirteenth day the patient became comatose,
+but could be roused to eat and drink. The temperature on the following
+day fell below 95° and the patient was still comatose. Death fifteenth
+day.
+
+Examination of the spinal (lumbar) cord showed acute disseminated
+myelitis. In one part there was an acute destruction of the anterior
+horn and an infiltration of round cells. In another portion Clarke's
+column had been destroyed. The perivascular sheaths were crowded with
+small round cells and the meninges were congested. Some of the cells of
+the anterior horn were swollen and the nuclei eccentric; chromatolysis
+had occurred in many of them.
+
+As for treatment, Castellani and Chalmers (1910), recommend bathing the
+part well with a solution of ammonia (one in five, or one in ten). After
+bathing, apply a dressing of the same alkali or, if there is much
+swelling and redness, an ice-bag. If necessary, hypodermic injections of
+morphine may be given to relieve the pain. At a later period
+fomentations may be required to reduce the local inflammation.
+
+
+THE HEXAPODA OR TRUE INSECTS
+
+There are a number of HEXAPODA, or true insects, which are, in one way
+or another, poisonous to man. These belong primarily to the orders
+Hemiptera, or true bugs; Lepidoptera, or butterflies and moths (larval
+forms); Diptera, or flies; Coleoptera, or beetles; and Hymenoptera, or
+ants, bees, and wasps. There are various ways in which they may be
+poisonous.
+
+1. _Piercing_ or _biting_ forms may inject an irritating or poisonous
+saliva into the wound caused by their mouth-parts.
+
+2. _Stinging forms_ may inject a poison, from glands at the caudal end
+of the abdomen, into wounds produced by a specially modified ovipositer,
+the _sting_.
+
+3. _Nettling_ properties may be possessed by the hairs of the insect.
+
+4. _Vescicating_, or _poisonous blood plasma_, or _body fluids_ are
+known to exist in a large number of species and may, under exceptional
+circumstances, affect man.
+
+For convenience of discussion, we shall consider poisonous insects under
+these various headings. In this, as in the preceding discussion, no
+attempt will be made to give an exhaustive list of the poisonous forms.
+Typical instances will be selected and these will be chosen largely from
+North American species.
+
+
+PIERCING OR BITING INSECTS POISONOUS TO MAN
+
+
+HEMIPTERA
+
+Several families of the true bugs include forms which, while normally
+inoffensive, are capable of inflicting painful wounds on man. In these,
+as in all of the Hemiptera, the mouth-parts are modified to form an
+organ for piercing and sucking. This is well shown by the accompanying
+illustration (fig. 16).
+
+The upper lip, or _labrum_, is much reduced and immovable, the lower
+lip, or _labium_, is elongated to form a jointed sheath, within which
+the lance-like mandibles and maxillæ are enclosed. The mandibles are
+more or less deeply serrate, depending on the species concerned.
+
+[Illustration: 16. Beak of hemipteron.]
+
+The poison is elaborated by the salivary glands, excepting, possibly, in
+_Belostoma_ where Locy is inclined to believe that it is secreted by the
+maxillary glands. The salivary glands of the Hemiptera have been the
+subject of much study but the most recent, comprehensive work has been
+done by Bugnion and Popoff, (1908 and 1910) to whose text the reader is
+referred for details.
+
+The Hemiptera have two pairs of salivary glands: the _primary gland_, of
+which the efferent duct leads to the salivary syringe, and the
+_accessory gland_, of which the very long and flexuous duct empties into
+the primary duct at its point of insertion. Thus, when one observes the
+isolated primary gland it appears as though it had efferent ducts
+inserted at the same point. In _Nepa_ and the _Fulgoridæ_ there are two
+accessory glands and therefore apparently three ducts at the same point
+on the primary gland. The _ensemble_ differs greatly in appearance in
+different species but we shall show here Bugnion and Popoff's figure of
+the apparatus of _Notonecta maculata_, a species capable of inflicting a
+painful bite on man (fig. 17).
+
+[Illustration: 17. Salivary glands of Notonecta maculata. After Bugnion
+and Popoff.]
+
+[Illustration: 18. Pharyngeal syringe or salivary pump of Fulgora
+maculata. After Bugnion and Popoff.]
+
+[Illustration: 19. Heteroptera, (_a_) Melanolestes picipes; (_b_)
+Notonecta undulata; (_c_, _d_) Aradus robustus (_c_) adult, (_d_) nymph,
+much enlarged; (_e_) Arilus cristatus; (_f_) Belostoma americana; (_g_)
+Nabis (Coriscus) subcoleoptratus, enlarged; (_h_) Cimex lectularius,
+(_i_) Oeciacus vicarius, much enlarged; (_j_) Lyctocoris fitchii, much
+enlarged. After Lugger.]
+
+Accessory to the salivary apparatus there is on the ventral side of the
+head, underneath the pharynx, a peculiar organ which the Germans have
+called the "Wanzenspritze," or syringe. The accompanying figure of the
+structure in _Fulgora maculata_ (fig. 18) shows its relation to the
+ducts of the salivary glands and to the beak. It is made up of a
+dilatation forming the body of the pump, in which there is a chitinous
+piston. Attached to the piston is a strong retractor muscle. The
+function of the salivary pump is to suck up the saliva from the salivary
+ducts and to force it out through the beak.
+
+Of the Hemiptera reported as attacking man, we shall consider briefly
+the forms most frequently noted.
+
+
+The NOTONECTIDÆ, or _back swimmers_, (fig. 19_b_) are small, aquatic
+bugs that differ from all others in that they always swim on their
+backs. They are predaceous; feeding on insects and other small forms.
+When handled carelessly they are able to inflict a painful bite, which
+is sometimes as severe as the sting of a bee. In fact, they are known in
+Germany as "Wasserbienen."
+
+
+The BELOSTOMATIDÆ, or _giant water bugs_, (fig. 19_f_) include the
+largest living Hemiptera. They are attracted to lights and on account of
+the large numbers which swarm about the electric street lamps in some
+localities they have received the popular name "electric light bugs."
+Our largest representatives in the northern United States belong to the
+two genera _Belostoma_ and _Banacus_, distinguished from each other by
+the fact that _Belostoma_ has a groove on the under side of the femur of
+the front leg, for the reception of the tibia.
+
+The salivary glands of Belostoma were figured by Leidy (1847) and later
+were studied in more detail by Locy (1884). There are two pairs of the
+glands, those of one pair being long and extending back as far as the
+beginning of the abdomen, while the others are about one-fourth as long.
+They lie on either side of the oesophagus. On each side of the
+oesophagus there is a slender tube with a sigmoid swelling which may
+serve as a poison reservoir. In addition to this salivary system, there
+is a pair of very prominent glands on the ventral side of the head,
+opening just above the base of the beak. These Locy has called the
+"cephalic glands" and he suggests that they are the source of the
+poison. They are the homologues of the maxillary glands described for
+other Hemiptera, and it is by no means clear that they are concerned
+with the production of venom. It seems more probable that in
+_Belostoma_, as in other Hemiptera, it is produced by the salivary
+glands, though the question is an open one.
+
+The Belostomatidæ feed not only on insects, but on small frogs, fish,
+salamanders and the like. Matheson (1907) has recorded the killing of a
+good-sized bird by _Belostoma americana_. A woodpecker, or flicker, was
+heard to utter cries of distress, and fluttered and fell from a tree. On
+examination it was found that a bug of this species had inserted its
+beak into the back part of the skull and was apparently busily engaged
+in sucking the blood or brains of the bird. Various species of
+_Belostoma_ have been cited as causing painful bites in man. We can
+testify from personal experience that the bite of _Belostoma americana_
+may almost immediately cause severe, shooting pains that may extend
+throughout the arm and that they may be felt for several days.
+
+[Illustration: 20. Reduvius (Opsicoetus) personatus. (×2).]
+
+Relief from the pain may be obtained by the use of dilute ammonia, or a
+menthol ointment. In the not uncommon case of secondary infection the
+usual treatment for that should be adopted.
+
+[Illustration: 21. (_a_) Reduvius personatus, nymph. Photograph by M. V.
+S.]
+
+
+The REDUVIIDÆ, or _assassin-bugs_ are capable of inflicting very painful
+wounds, as most collectors of Hemiptera know to their sorrow. Some
+species are frequently to be found in houses and outhouses and Dr.
+Howard suggests that many of the stories of painful spider bites relate
+to the attack of these forms.
+
+[Illustration: 21. (_b_) Reduvius personatus, adult (×2) Photograph by
+M. V. S.]
+
+An interesting psychological study was afforded in the summer of 1899,
+by the "kissing-bug" scare which swept over the country. It was reported
+in the daily papers that a new and deadly bug had made its appearance,
+which had the unpleasant habit of choosing the lips or cheeks for its
+point of attack on man. So widespread were the stories regarding this
+supposedly new insect that station entomologists all over the country
+began to receive suspected specimens for identification. At Cornell
+there were received, among others, specimens of stone-flies, may-flies
+and even small moths, with inquiries as to whether they were
+"kissing-bugs."
+
+[Illustration: 22. Rasahus biguttatus. (×2). After Howard.]
+
+Dr. L. O. Howard has shown that the scare had its origin in newspaper
+reports of some instances of bites by either _Melanolestes picipes_
+(fig. 19a) or _Opsicoetes personatus_ (fig. 20), in the vicinity of
+Washington, D. C. He then discusses in considerable detail the more
+prominent of the Reduviidæ which, with greater or less frequency pierce
+the skin of human beings. These are _Opsicoetes personatus_,
+_Melanolestes picipes_, _Coriscus subcoleoptratus_ (fig. 19_g_),
+_Rasahus thoracicus_, _Rasahus biguttatus_ (fig. 22), _Conorhinus
+sanguisugus_ (fig. 71), and _Melanolestes abdominalis_ (fig. 23).
+
+[Illustration: 23. Melanolestes abdominalis (×2). After Marlatt.]
+
+One of the most interesting of these species is _Reduvius personatus_,
+(= _Opsicoetus personatus_), which is popularly known as the "masked
+bed-bug hunter." It owes this name to the fact that the immature nymphs
+(fig. 21) have their bodies and legs completely covered by dust and
+lint, and that they are supposed to prey upon bed-bugs. LeConte is
+quoted by Howard as stating that "This species is remarkable for the
+intense pain caused by its bite. I do not know whether it ever willingly
+plunges its rostrum into any person, but when caught, or unskilfully
+handled it always stings. In this case the pain is almost equal to the
+bite of a snake, and the swelling and irritation which result from it
+will sometimes last for a week."
+
+A species which very commonly attacks man is _Conorhinus sanguisugus_,
+the so-called "big bed-bug" of the south and southern United States. It
+is frequently found in houses and is known to inflict an exceedingly
+painful bite. As in the case of a number of other predaceous Hemiptera,
+the salivary glands of these forms are highly developed. The effect of
+the bite on their prey and, as Marlatt has pointed out, the constant and
+uniform character of the symptoms in nearly all cases of bites in man,
+clearly indicate that their saliva contains a specific substance. No
+satisfactory studies of the secretions have been made. On the other
+hand, Dr. Howard is doubtless right in maintaining that the very serious
+results which sometimes follow the bite are due to the introduction of
+extraneous poison germs. This is borne out by the symptoms of most of
+the cases cited in literature and also by the fact that treatment with
+corrosive sublimate, locally applied to the wound, has yielded favorable
+results.
+
+
+OTHER HEMIPTERA REPORTED AS POISONOUS TO MAN--A large number of other
+Hemiptera have been reported as attacking man. Of these, there are
+several species of Lygæidæ, Coreidæ, and Capsidæ. Of the latter, _Lygus
+pratensis_, the tarnished plant-bug, is reported by Professor Crosby as
+sucking blood. _Orthotylus flavosparsus_ is another Capsid which has
+been implicated. _Empoasca mali_ and _Platymetopius acutus_ of the
+Jassidæ have also been reported as having similar habits.
+
+Whenever the periodical cicada or "seventeen-year locust" becomes
+abundant, the newspapers contain accounts of serious results from its
+bites. The senior author has made scores of attempts to induce this
+species to bite and only once successfully. At that time the bite was in
+no wise more severe than a pin-prick. A student in our department
+reports a similar experience. There is no case on record which bears
+evidence of being worthy of any credence, whatsoever.
+
+Under the heading of poisonous Hemiptera we might consider the bed-bugs
+and the lice. These will be discussed later, as parasites and as
+carriers of disease, and therefore need only be mentioned here.
+
+
+DIPTERA
+
+Several species of blood-sucking Diptera undoubtedly secrete a saliva
+possessing poisonous properties. Chief among these are the Culicidæ, or
+mosquitoes, and the Simuliidæ, or black-flies. As we shall consider
+these forms in detail under the heading of parasitic species and
+insects transmitting disease, we shall discuss here only the poison of
+the mosquitoes.
+
+It is well known that mosquitoes, when they bite, inject into the wound
+a minute quantity of poison. The effect of this varies according to the
+species of mosquito and also depends very much on the susceptibility of
+the individual. Soon after the bite a sensation of itching is noticed
+and often a wheal, or eminence, is produced on the skin, which may
+increase to a considerable swelling. The scratching which is induced may
+cause a secondary infection and thus lead to serious results. Some
+people seem to acquire an immunity against the poison.
+
+The purpose of this irritating fluid may be, as Reaumur suggested, to
+prevent the coagulation of the blood and thus not only to cause it to
+flow freely when the insect bites but to prevent its rapid coagulation
+in the stomach. Obviously, it is not developed as a protective fluid,
+and its presence subjects the group to the additional handicap of the
+vengeance of man.
+
+[Illustration: 24. Diagram of a longitudinal section of a mosquito.]
+
+As to the origin of the poison, there has been little question, until
+recent years, that it was a secretion from the salivary glands.
+Macloskie (1888) showed that each gland is subdivided into three lobes,
+the middle of which differs from the others in having evenly granulated
+contents and staining more deeply than the others (fig. 24). This middle
+lobe he regarded as the source of the poison. Bruck, (1911), by the use
+of water, glycerine, chloroform, and other fluids, extracted from the
+bodies of a large number of mosquitoes a toxine which he calls
+_culicin_. This he assumes comes from the salivary glands. Animal
+experimentation showed that this extract possessed hemolytic powers.
+Inoculated into the experimenter's own skin it produced lesions which
+behaved exactly as do those of mosquito bites.
+
+Similarly, most writers on the subject have concurred with the view that
+the salivary glands are the source of the poison. However, recent work,
+especially that of Nuttall and Shipley (1903), and Schaudinn (1904), has
+shown that the evidence is by no means conclusive. Nuttall dissected out
+six sets (thirty-six acini) of glands from freshly killed _Culex
+pipiens_ and placed them in a drop of salt solution. The drop was
+allowed to dry, it being thought that the salt crystals would facilitate
+the grinding up of the glands with the end of a small glass rod, this
+being done under microscopic control. After grinding up, a small drop of
+water was added of the size of the original drop of saline, and an equal
+volume of human blood taken from the clean finger-tip was quickly mixed
+therewith, and the whole drawn up into a capillary tube. Clotting was
+not prevented and no hemolysis occurred. Salivary gland emulsion added
+to a dilute suspension of corpuscles did not lead to hemolysis. This
+experiment was repeated a number of times, with slight modification, but
+with similar results. The data obtained from the series "do not support
+the hypothesis that the salivary glands, at any rate in _Culex pipiens_,
+contain a substance which prevents coagulation."
+
+Much more detailed, and the more important experiments made along this
+line, are those of Schaudinn (1904). The results of these experiments
+were published in connection with a technical paper on the alternation
+of generations and of hosts in _Trypanosoma_ and _Spirochæta_, and for
+this reason seem to have largely escaped the notice of entomologists.
+They are so suggestive that we shall refer to them in some detail.
+
+Schaudinn observed that the three oesophageal diverticula (commonly,
+but incorrectly, known as the "sucking stomach") (fig. 24) usually
+contain large bubbles of gas and in addition, he always found yeast
+cells. On the ground of numerous observations, Schaudinn was convinced
+that these yeast plants are normal and constant commensals of the
+insect. He regarded them as the cause of the gas bubbles to be found in
+diverticula. It was found that as the insect fed, from time to time the
+abdomen underwent convulsive contractions which resulted in the emptying
+of the oesophageal diverticula and the salivary glands through blood
+pressure.
+
+In order to test the supposed toxic action of the salivary glands,
+Schaudinn repeatedly introduced them under his skin and that of his
+assistant, in a drop of salt solution, and never obtained a suggestion
+of the irritation following a bite of the insect, even though the glands
+were carefully rubbed to fragments after their implantation. Like
+Nuttall, he failed to get satisfactory evidence that the secretion of
+the salivary glands retarded coagulation of the blood.
+
+He then carefully removed the oesophageal diverticula with their
+content of yeast and introduced them into an opening in the skin of the
+hand. Within a few seconds there was noticeable the characteristic
+itching irritation of the mosquito bite; and in a short time there
+appeared reddening and typical swelling. This was usually much more
+severe than after the usual mosquito bite, and the swelling persisted
+and itched longer. This was because by the ordinary bite of the mosquito
+most of the yeast cells are again sucked up, while in these experiments
+they remained in the wound. These experiments were repeated a number of
+times on himself, his assistant and others, and always with the same
+result. From them Schaudinn decided that the poisonous action of the
+mosquito bite is caused by an enzyme from a commensal fungus. These
+conclusions have not, as yet, been satisfactorily tested.
+
+Relief from the effect of the mosquito bite may be obtained by bathing
+the swellings with weak ammonia or, according to Howard, by using moist
+soap. The latter is to be rubbed gently on the puncture and is said to
+speedily allay the irritation. Howard also quotes from the _Journal of
+Tropical Medicine and Hygiene_ to the effect that a few drops of a
+solution of thirty to forty grains of iodine to an ounce of saponated
+petroleum rubbed into the mosquito bite, or wasp sting, allay the pain
+instantaneously.
+
+Methods of mosquito control will be discussed later, in considering
+these insects as parasites and as carriers of disease.
+
+
+STINGING INSECTS
+
+The stinging insects all belong to the order HYMENOPTERA. In a number of
+families of this group the ovipositor is modified to form a sting and is
+connected with poison-secreting glands. We shall consider the apparatus
+of the honey-bee and then make briefer reference to that of other forms.
+
+
+APIS MELLIFICA, THE HONEY BEE--The sting of the worker honey-bee is
+situated within a so-called sting chamber at the end of the abdomen.
+This chamber is produced by the infolding of the greatly reduced and
+modified eighth, ninth and tenth abdominal segments into the seventh.[D]
+From it the dart-like sting can be quickly exserted.
+
+The sting (fig. 25) is made up of a central shaft, ventro-laterad of
+which are the paired _lancets_, or darts, which are provided with sharp,
+recurved teeth. Still further laterad lie the paired whitish,
+finger-like _sting palpi_. Comparative morphological as well as
+embryological studies have clearly established that these three parts
+correspond to the three pairs of gonopophyses of the ovipositor of more
+generalized insects.
+
+[Illustration: 25. Sting of a honey bee. _Psn Sc_, base of acid poison
+gland; _B Gl_, alkaline poison gland; _Stn Plp_, sting palpi; _Sh B_,
+bulb of sting; _Sh A_, basal arm; _Lct_, lancets or darts; _Sh s_, shaft
+of sting. Modified from Snodgrass.]
+
+[Illustration: 26. Poison apparatus of a honey bee. Modified from
+Snodgrass.]
+
+An examination of the internal structures (fig. 26) reveals two distinct
+types of poison glands, the acid-secreting and the alkaline-secreting
+glands, and a prominent poison reservoir. In addition, there is a small
+pair of accessory structures which have been called lubricating glands,
+on account of the supposed function of their product. The acid-secreting
+gland empties into the distal end of the poison reservoir which in turn
+pours the secretion into the muscular bulb-like enlargement at the base
+of the shaft. The alkaline secreting gland empties into the bulb ventrad
+of the narrow neck of the reservoir.
+
+The poison is usually referred to as formic acid. That it is not so
+easily explained has been repeatedly shown and is evidenced by the
+presence of the two types of glands. Carlet maintains that the product
+of either gland is in itself innocent,--it is only when they are
+combined that the toxic properties appear.
+
+The most detailed study of the poison of the honey-bee is that of Josef
+Langer (1897), who in the course of his work used some 25,000 bees.
+Various methods of obtaining the active poison for experimental purposes
+were used. For obtaining the pure secretion, bees were held in the
+fingers and compressed until the sting was exserted, when a clear drop
+of the poison was visible at its tip. This was then taken up in a
+capillary tube or dilute solutions obtained by dipping the tip of the
+sting into a definite amount of distilled water.
+
+An aqueous solution of the poison was more readily obtained by pulling
+out the sting and poison sacs by means of forceps, and grinding them up
+in water. The somewhat clouded fluid was then filtered one or more
+times. For obtaining still greater quantities, advantage was taken of
+the fact that while alcohol coagulates the poison, the active principle
+remains soluble in water. Hence the stings with the annexed glands where
+collected in 96 per cent alcohol, after filtering off of the alcohol
+were dried at 40° C., then rubbed to a fine powder and this was
+repeatedly extracted with water. Through filtering of this aqueous
+extract there was obtained a yellowish-brown fluid which produced the
+typical reactions, according to concentration of the poison.
+
+The freshly expelled drop of poison is limpid, of distinct acid
+reaction, tastes bitter and has a delicate aromatic odor. On
+evaporation, it leaves a sticky residue, which at 100 degrees becomes
+fissured, and suggests dried gum arabic. The poison is readily soluble
+in water and possesses a specific gravity of 1.1313. On drying at room
+temperature, it leaves a residue of 30 per cent, which has not lost in
+poisonous action or in solubility. In spite of extended experiments,
+Langer was unable to determine the nature of the active principle. He
+showed that it was not, as had been supposed, an albuminous body, but
+rather an organic base.
+
+The pure poison, or the two per cent aqueous solution, placed on the
+uninjured skin showed absolutely no irritating effect, though it
+produced a marked reaction on the mucus membrane of the nose or eye. A
+single drop of one-tenth per cent aqueous solution of the poison brought
+about a typical irritation in the conjunctiva of the rabbit's eye. On
+the other hand, the application of a drop of the poison, or its
+solution, to the slightest break in the skin, or by means of a needle
+piercing the skin, produced typical effects. There is produced a local
+necrosis, in the neighborhood of which there is infiltration of
+lymphocytes, oedema, and hyperæmia.
+
+The effect of the sting on man (fig. 27) is usually transitory but there
+are some individuals who are made sick for hours, by a single sting.
+Much depends, too, on the place struck. It is a common experience that
+an angry bee will attempt to reach the eye of its victim and a sting on
+the lid may result in severe and prolonged swelling. In the case of a
+man stung on the cheek, Legiehn observed complete aphonia and a breaking
+out of red blotches all over the body. A sting on the tongue has been
+known to cause such collateral oedema as to endanger life through
+suffocation. Cases of death of man from the attacks of bees are rare but
+are not unknown. Such results are usually from a number of stings but,
+rarely, death has been known to follow a single sting, entering a blood
+vessel of a particularly susceptible individual.
+
+[Illustration: Effect of bee stings. After Root.]
+
+It is clearly established that partial immunity from the effects of the
+poison may be acquired. By repeated injections of the venom, mice have
+been rendered capable of bearing doses that certainly would have killed
+them at first. It is a well-known fact that most bee-keepers become
+gradually hardened to the stings, so that the irritation and the
+swelling become less and less. Some individuals have found this immunity
+a temporary one, to be reacquired each season. A striking case of
+acquired immunity is related by the Roots in their "A B C and X Y Z of
+Bee Culture." The evidence in the case is so clear that it should be
+made more widely available and hence we quote it here.
+
+A young man who was determined to become a bee-keeper, was so
+susceptible to the poison that he was most seriously affected by a
+single sting, his body breaking out with red blotches, breathing growing
+difficult, and his heart action being painfully accelerated. "We finally
+suggested taking a live bee and pressing it on the back of his hand
+until it merely pierced his skin with the sting, then immediately
+brushing off both bee and sting. This was done and since no serious
+effect followed, it was repeated inside of four or five days. This was
+continued for some three or four weeks, when the patient began to have a
+sort of itching sensation all over his body. The hypodermic injections
+of bee-sting poison were then discontinued. At the end of a month they
+were repeated at intervals of four or five days. Again, after two or
+three weeks the itching sensation came on, but it was less pronounced.
+The patient was given a rest of about a month, when the doses were
+repeated as before." By this course of treatment the young man became so
+thoroughly immunized that neither unpleasant results nor swelling
+followed the attacks of the insects and he is able to handle bees with
+the same freedom that any experienced bee-keeper does.
+
+In an interesting article in the _Entomological News_ for November,
+1914, J. H. Lovell calls attention to the fact that "There has been a
+widespread belief among apiarists that a beekeeper will receive more
+stings when dressed in black than when wearing white clothing. A large
+amount of evidence has been published in the various bee journals
+showing beyond question that honey-bees under certain conditions
+discriminate against black. A few instances may be cited in
+illustration. Of a flock of twelve chickens running in a bee-yard seven
+black ones were stung to death, while five light colored ones escaped
+uninjured. A white dog ran among the bee-hives without attracting much
+attention, while at the same time a black dog was furiously assailed by
+the bees. Mr. J. D. Byer, a prominent Canadian beekeeper, relates that a
+black and white cow, tethered about forty feet from an apiary, was one
+afternoon attacked and badly stung by bees. On examination it was found
+that the black spots had five or six stings to one on the white. All
+noticed this fact, although no one was able to offer any explanation. A
+white horse is in much less danger of being stung, when driven near an
+apiary, than a black one. It has, indeed, been observed repeatedly that
+domestic animals of all kinds, if wholly or partially black, are much
+more liable to be attacked by bees, if they wander among the hives, than
+those which are entirely white."
+
+In order to test the matter experimentally, the following series of
+experiments was performed. In the language of the investigator:
+
+"On a clear, warm day in August I dressed wholly in white with the
+exception of a black veil. Midway on the sleeve of my right arm there
+was sewed a band of black cloth ten inches wide. I then entered the
+bee-yard and, removing the cover from one of the hives, lifted a piece
+of comb with both hands and gently shook it. Instantly many of the bees
+flew to the black band, which they continued to attack as long as they
+were disturbed. Not a single bee attempted to sting the left sleeve,
+which was of course entirely white, and very few even alighted upon it."
+
+"This experiment was repeated a second, third and fourth time; in each
+instance with similar results. I estimated the number of bees on the
+band of black cloth at various moments was from thirty to forty; it was
+evident from their behavior that they were extremely irritable. To the
+left white sleeve and other portions of my clothing they paid very
+little attention; but the black veil was very frequently attacked."
+
+"A few days later the experiments were repeated, but the band of black
+cloth, ten inches wide, was sewed around my left arm instead of around
+the right arm as before. When the bees were disturbed, after the hive
+cover had been removed, they fiercely attacked the band of black cloth
+as in the previous experiences; but the right white sleeve and the white
+suit were scarcely noticed. At one time a part of the black cloth was
+almost literally covered with furiously stinging bees, and the black
+veil was assailed by hundreds. The bees behaved in a similar manner when
+a second hive on the opposite side of the apiary was opened."
+
+"A white veil which had been procured for this purpose, was next
+substituted for the black veil. The result was most surprising, for,
+whereas in the previous experiments hundreds of bees had attacked the
+black veil, so few flew against the white veil as to cause me no
+inconvenience. Undoubtedly beekeepers will find it greatly to their
+advantage to wear white clothing when working among their colonies of
+bees and manipulating the frames of the hives."
+
+When a honey-bee stings, the tip of the abdomen, with the entire sting
+apparatus, is torn off and remains in the wound. Here the muscles
+continue to contract, for some minutes, forcing the barbs deeper and
+deeper into the skin, and forcing out additional poison from the
+reservoir.
+
+Treatment, therefore, first consists in removing the sting without
+squeezing out additional poison. This is accomplished by lifting and
+scraping it out with a knife-blade or the fingernail instead of grasping
+and pulling it out. Local application of alkalines, such as weak
+ammonia, are often recommended on the assumption that the poison is an
+acid to be neutralized on this manner, but these are of little or no
+avail. They should certainly not be rubbed in, as that would only
+accelerate the absorption of the poison. The use of cloths wrung out in
+hot water and applied as hot as can be borne, affords much relief in the
+case of severe stings. The application of wet clay, or of the end of a
+freshly cut potato is sometimes helpful.
+
+In extreme cases, where there is great susceptibility, or where there
+may have been many stings, a physician should be called. He may find
+strychnine injections or other treatment necessary, if general symptoms
+develop.
+
+[Illustration: 28. The poison apparatus of Formica. Wheeler, after
+Forel.]
+
+
+OTHER STINGING FORMS--Of the five thousand, or more, species of bees,
+most possess a sting and poison apparatus and some of the larger forms
+are capable of inflicting a much more painful sting than that of the
+common honey-bee. In fact, some, like the bumble bees, possess the
+advantage that they do not lose the sting from once using it, but are
+capable of driving it in repeatedly. In the tropics there are found many
+species of stingless bees but these are noted for their united efforts
+to drive away intruders by biting. Certain species possess a very
+irritating saliva which they inject into the wounds.
+
+The ants are not ordinarily regarded as worthy of consideration under
+the heading of "stinging insects" but as a matter of fact, most of them
+possess well developed stings and some of them, especially in the
+tropics, are very justly feared. Even those which lack the sting possess
+well-developed poison glands and the parts of the entire stinging
+apparatus, in so far as it is developed in the various species, may
+readily be homologized with those of the honey-bee.
+
+The ants lacking a sting are those of the subfamily CAMPONOTINÆ, which
+includes the largest of our local species. It is an interesting fact
+that some of these species possess the largest poison glands and
+reservoir (fig. 28) and it is found that when they attack an enemy they
+bring the tip of the abdomen forward and spray the poison in such a way
+that it is introduced into the wound made by the powerful mandibles.
+
+[Illustration: 29. A harmless, but much feared larva, the "tomato worm."
+Natural size. Photograph by M. V. S.]
+
+More feared than any of the other Hymenoptera are the hornets and wasps.
+Of these there are many species, some of which attain a large size and
+are truly formidable. Phisalix (1897), has made a study of the venom of
+the common hornet and finds that, like the poison of the honey-bee, it
+is neither an albuminoid nor an alkaloid. Its toxic properties are
+destroyed at 120° C. Phisalix also says that the venom is soluble in
+alcohol. If this be true, it differs in this respect from that of the
+bee. An interesting phase of the work of Phisalix is that several of her
+experiments go to show that the venom of hornets acts as a vaccine
+against that of vipers.
+
+
+NETTLING INSECTS
+
+So far, we have considered insects which possess poison glands connected
+with the mouth-parts or a special sting and which actively inject their
+poison into man. There remain to be considered those insects which
+possess poisonous hairs or body fluids which, under favorable
+circumstances, may act as poisons. To the first of these belong
+primarily the larvæ of certain Lepidoptera.
+
+
+LEPIDOPTERA
+
+[Illustration: 30. Another innocent but much maligned caterpillar, the
+larva of the Regal moth. Photograph by M. V. S.]
+
+When we consider the reputedly poisonous larvæ of moths and butterflies,
+one of the first things to impress us is that we cannot judge by mere
+appearance. Various species of Sphingid, or hawk-moth larvæ, bear at the
+end of the body a chitinous horn, which is often referred to as a
+"sting" and regarded as capable of inflicting dangerous wounds. It would
+seem unnecessary to refer to this absurd belief if it were not that each
+summer the newspapers contain supposed accounts of injury from the
+"tomato worm" (fig. 29) and others of this group. The grotesque, spiny
+larva (fig. 30) of one of our largest moths, _Citheronia regalis_ is
+much feared though perfectly harmless, and similar instances could be
+multiplied.
+
+[Illustration: 31. The flannel moth (Lagoa crispata). (_a_) Poisonous
+larva.]
+
+[Illustration: 31. (_b_) Adult. Enlarged. Photographs by M. V. S.]
+
+But if the larvæ are often misjudged on account of their ferocious
+appearance, the reverse may be true. A group of most innocent looking
+and attractive caterpillars is that of the flannel-moth larvæ, of which
+_Lagoa crispata_ may be taken as an example. Its larva (fig. 31) has a
+very short and thick body, which is fleshy and completely covered and
+hidden by long silken hairs of a tawny or brown color, giving a convex
+form to the upper side. Interspersed among these long hairs are
+numerous short spines connected with underlying hypodermal poison
+glands. These hairs are capable of producing a marked nettling effect
+when they come in contact with the skin. This species is found in our
+Atlantic and Southern States. Satisfactory studies of its poisonous
+hairs and their glands have not yet been made.
+
+[Illustration: 32 The poisonous saddle back caterpillar. Empretia
+(Sibine) stimulea. Photograph by M. V. S.]
+
+[Illustration: 33_a_. Io moth larvæ on willow. Photograph by M. V. S.]
+
+_Sibine stimulea (Empretia stimulea)_, or the saddle-back caterpillar
+(fig. 32), is another which possesses nettling hairs. This species
+belongs to the group of Eucleidæ, or slug caterpillars. It can be
+readily recognized by its flattened form, lateral, bristling spines and
+by the large green patch on the back resembling a saddle-cloth, while
+the saddle is represented by an oval, purplish-brown spot. The small
+spines are venomous and affect some persons very painfully. The larva
+feeds on the leaves of a large variety of forest trees and also on
+cherry, plum, and even corn leaves. It is to be found throughout the
+Eastern and Southern United States.
+
+[Illustration: 33_b_. Io moth. Full grown larva. Photograph by M. V. S.]
+
+[Illustration: 34. Io moth. Adult. Photograph by M. V. S.]
+
+_Automeris io_ is the best known of the nettling caterpillars. It is the
+larva of the Io moth, one of the Saturniidæ. The mature caterpillar,
+(fig. 33), which reaches a length of two and one-half inches, is of a
+beautiful pale green with sublateral stripes of cream and red color and
+a few black spines among the green ones. The green radiating spines give
+the body a mossy appearance. They are tipped with a slender chitinous
+hair whose tip is readily broken off in the skin and whose poisonous
+content causes great irritation. Some individuals are very susceptible
+to the poison, while others are able to handle the larvæ freely without
+any discomfort. The larvæ feed on a wide range of food plants. They are
+most commonly encountered on corn and on willow, because of the
+opportunities for coming in contact with them.
+
+[Illustration: 35. Larva of brown-tail moth. (Natural size). Photograph
+by M. V. S.]
+
+The larvæ of the brown-tail moth (_Euproctis chrysorrhoea_) (fig. 35
+and 36), where they occur in this country, are, on account of their
+great numbers, the most serious of all poisonous caterpillars. It is not
+necessary here, to go into details regarding the introduction of this
+species from Europe into the New England States. This is all available
+in the literature from the United States Bureau of Entomology and from
+that of the various states which are fighting the species. Suffice to
+say, there is every prospect that the pest will continue to spread
+throughout the Eastern United States and Canada and that wherever it
+goes it will prove a direct pest to man as well as to his plants.
+
+Very soon after the introduction of the species there occurred in the
+region where it had gained a foothold, a mysterious dermatitis of man.
+The breaking out which usually occurred on the neck or other exposed
+part of the body was always accompanied by an intense itching. It was
+soon found that this dermatitis was caused by certain short, barbed
+hairs of the brown-tail caterpillars and that not only the caterpillars
+but their cocoons and even the adult female moths might harbor these
+nettling hairs and thus give rise to the irritation. In many cases the
+hairs were wafted to clothing on the line and when this was worn it
+might cause the same trouble. Still worse, it was found that very
+serious internal injury was often caused by breathing or swallowing the
+poisonous hairs.
+
+[Illustration: 36. Browntail moths. One male and two females. Photograph
+by M. V. S.]
+
+The earlier studies seemed to indicate that the irritation was purely
+mechanical in origin, the result of the minute barbed hairs working into
+the skin in large numbers. Subsequently, however, Dr. Tyzzer (1907)
+demonstrated beyond question that the trouble was due to a poison
+contained in the hairs. In the first place, it is only the peculiar
+short barbed hairs which will produce the dermatitis when rubbed on the
+skin, although most of the other hairs are sharply barbed. Moreover, it
+was found that in various ways the nettling properties could be
+destroyed without modifying the structure of the hairs. This was
+accomplished by baking for one hour at 110° C, by warming to 60° C in
+distilled water, or by soaking in one per cent. or in one-tenth per
+cent. of potassium hydrate or sodium hydrate. The most significant part
+of his work was the demonstration of the fact that if the nettling
+hairs are mingled with blood, they immediately produce a change in the
+red corpuscles. These at once become coarsely crenated, and the roleaux
+are broken up in the vicinity of the hair (fig. 37_b_). The corpuscles
+decrease in size, the coarse crenations are transformed into slender
+spines which rapidly disappear, leaving the corpuscles in the form of
+spheres, the light refraction of which contrasts them sharply with the
+normal corpuscles. The reaction always begins at the basal sharp point
+of the hair. It could not be produced by purely mechanical means, such
+as the mingling of minute particles of glass wool, the barbed hairs of a
+tussock moth, or the other coarser hairs of the brown-tail, with the
+blood.
+
+[Illustration: 37. (_a_) Ordinary hairs and three poison hairs of
+subdorsal and lateral tubercles of the larva of the browntail moth.
+Drawing by Miss Kephart.]
+
+The question of the source of the poison has been studied in our
+laboratory by Miss Cornelia Kephart. She first confirmed Dr. Tyzzer's
+general results and then studied carefully fixed specimens of the larvæ
+to determine the distribution of the hairs and their relation to the
+underlying tissues.
+
+[Illustration: 37. (_b_) Effect of the poison on the blood corpuscles of
+man. After Tyzzer.]
+
+The poison hairs (fig. 37), are found on the subdorsal and lateral
+tubercles (fig. 38), in bunches of from three to twelve on the minute
+papillæ with which the tubercles are thickly covered. The underlying
+hypodermis is very greatly thickened, the cells being three or four
+times the length of the ordinary hypodermal cells and being closely
+crowded together. Instead of a pore canal through the cuticula for each
+individual hair, there is a single pore for each papillæ on a tubercle,
+all the hairs of the papilla being connected with the underlying cells
+through the same pore canal, (figs. 39 and 40).
+
+[Illustration: 38. Cross section of the larva of the browntail moth
+showing the tubercles bearing the poison hairs. Drawing by Miss
+Kephart.]
+
+The hypodermis of this region is of two distinct types of cells. First,
+there is a group of slender fusiform cells, one for each poison hair on
+the papilla, which are the trichogen, or hair-formative cells. They are
+crowded to one side and towards the basement membrane by a series of
+much larger, and more prominent cells (fig. 40), of which there is a
+single one for each papilla. These larger cells have a granular
+protoplasm with large nuclei and are obviously actively secreting. They
+are so characteristic in appearance as to leave no question but that
+they are the true poison glands.
+
+[Illustration: 39. Epithelium underlying poison hairs of the larva of
+the browntail moth. Drawing by Miss Kephart.]
+
+Poisonous larvæ of many other species have been reported from Europe and
+especially from the tropics but the above-mentioned species are the more
+important of those occurring in the United States and will serve as
+types. It should be noted in this connection that through some curious
+misunderstanding Goeldi (1913) has featured the larva of _Orgyia
+leucostigma_, the white-marked tussock moth, as the most important of
+the poisonous caterpillars of this country. Though there are occasional
+reports of irritation from its hairs such cases are rare and there is no
+evidence that there is any poison present. Indeed, subcutaneous
+implantation of the hairs leads to no poisoning, but merely to temporary
+irritation.
+
+[Illustration: 40. Same as figure 39, on larger scale.]
+
+Occasionally, the hairs of certain species of caterpillars find
+lodgement in the conjunctiva, cornea, or iris of the eye of man and give
+rise to the condition known as _opthalmia nodosa_. The essential feature
+of this trouble is a nodular conjunctivitis which simulates tuberculosis
+of the conjunctiva and hence has been called _pseudo-tubercular_. It may
+be distinguished microscopically by the presence of the hairs.
+
+[Illustration: 41. (_a_) Nodular conjunctivitis in the eye of a child.
+De Schweinitz and Shumway.]
+
+Numerous cases of opthalmia nodosa are on record. Of those from this
+country, one of the most interesting is reported by de Schweinitz and
+Shumway (1904). It is that of a child of fifteen years whose eye had
+become inflamed owing to the presence of some foreign body. Downward and
+inward on the bulbar conjunctiva were a number of flattened,
+grayish-yellow nodules, between which was a marked congestion of the
+conjunctival and episcleral vessels (fig. 41_a_). Twenty-seven nodules
+could be differentiated, those directly in the center of the collection
+being somewhat confluent and assuming a crescentic and circular
+appearance. The nodules were excised and, on sectioning, were found to
+be composed of a layer of spindle cells and round cells, outside of
+which the tissue was condensed into a capsule. The interior consisted of
+epithelioid cells, between which was a considerable intercellular
+substance. Directly in the center of a certain number of nodules was
+found the section of a hair (fig. 41_b_). The evidence indicated that
+the injury had resulted from playing with caterpillars of one of the
+Arctiid moths, _Spilosoma virginica_. Other reported cases have been
+caused by the hairs of larvæ of _Lasiocampa rubi_, _L. pini_,
+_Porthetria dispar_, _Psilura monacha_ and _Cnethocampa processionea_.
+
+[Illustration: 41_b_. Section through one of the nodules showing the
+caterpillar hair. De Schweinitz and Shumway.]
+
+
+RELIEF FROM POISONING BY NETTLING LARVÆ--The irritation from nettling
+larvæ is often severe and, especially in regions where the brown-tail
+abounds, inquiries as to treatment arise. In general, it may be said
+that cooling lotions afford relief, and that scratching, with the
+possibilities of secondary infection, should be avoided, in so far as
+possible.
+
+Among the remedies usually at hand, weak solutions of ammonia, or a
+paste of ordinary baking soda are helpful. Castellani and Chalmers
+recommend cleaning away the hairs by bathing the region with an alkaline
+lotion, such as two per cent solution of bicarbonate of soda, and then
+applying an ointment of ichthyol (10%).
+
+In the brown-tail district, there are many proprietary remedies of which
+the best ones are essentially the following, as recommended by Kirkland
+(1907):
+
+    Carbolic acid    ½ drachm.
+    Zinc oxide       ½ oz.
+    Lime water       8 oz.
+
+Shake thoroughly and rub well into the affected parts.
+
+In some cases, and especially where there is danger of secondary
+infection, the use of a weak solution of creoline (one teaspoonful to a
+quart of water), is to be advised.
+
+
+VESCICATING INSECTS AND THOSE POSSESSING OTHER POISONS IN THEIR BLOOD
+PLASMA
+
+We have seen that certain forms, for example, the poisonous spiders, not
+only secrete a toxine in their poison glands, but that such a substance
+may be extracted from other parts of their body, or even their eggs.
+There are many insects which likewise possess a poisonous blood plasma.
+Such forms have been well designated by Taschenberg as _cryptotoxic_
+([Greek: kryptos] = hidden). We shall consider a few representative
+forms.
+
+[Illustration: 42_a_. Blister beetle.]
+
+[Illustration: 42_b_. An American blister beetle. Meloe angusticollis.
+Photograph by M. V. S.]
+
+
+THE BLISTER BEETLES--Foremost among the cryptotoxic insects are the
+_Meloidæ_ or "blister beetles," to which the well-known "Spanish fly"
+(fig. 42_a_), formerly very generally used in medical practice, belongs.
+The vescicating property is due to the presence in the blood plasma of a
+peculiar, volatile, crystalline substance known as _cantharidin_, which
+is especially abundant in the reproductive organs of the beetle.
+According to Kobert, the amount of this varies in different species from
+.4 or .5% to 2.57% of the dry weight of the beetle.
+
+While blister beetles have been especially used for external
+application, they are also at times used internally as a stimulant and a
+diuretic. The powder or extract was formerly much in vogue as an
+aphrodisiac, and formed the essential constituent of various philters,
+or "love powders". It is now known that its effects on the reproductive
+organs appear primarily after the kidneys have been affected to such an
+extent as to endanger life, and that many cases of fatal poison have
+been due to its ignorant use.
+
+There are many cases on record of poisoning and death due to internal
+use, and in some instances from merely external application. There are
+not rarely cases of poisoning of cattle from feeding on herbage bearing
+a large number of the beetles and authentic cases are known of human
+beings who have been poisoned by eating the flesh of such cattle. Kobert
+states that the beetles are not poisonous to birds but that the flesh of
+birds which have fed on them is poisonous to man, and that if the flesh
+of chickens or frogs which have fed on the cantharidin be fed to cats it
+causes in them the same symptoms as does the cantharidin.
+
+Treatment of cases of cantharidin poison is a matter for a skilled
+physician. Until he can be obtained, emetics should be administered and
+these should be followed by white of egg in water. Oils should be
+avoided, as they hasten the absorption of the poison.
+
+
+OTHER CRYPTOTOXIC INSECTS--Though the blister beetles are the best known
+of the insects with poisonous blood plasma, various others have been
+reported and we shall refer to a few of the best authenticated.
+
+One of the most famous is the Chrysomelid beetle, _Diamphidia simplex_,
+the body fluids of whose larvæ are used by certain South African bushmen
+as an arrow poison. Its action is due to the presence of a toxalbumin
+which exerts a hæmolytic action on the blood, and produces inflammation
+of the subcutaneous connective tissue and mucous membranes. Death
+results from general paralysis. Krause (1907) has surmised that the
+active principle may be a bacterial toxin arising from decomposition of
+the tissues of the larva, but he presents no support of this view and it
+is opposed by all the available evidence.
+
+In China, a bug, _Heuchis sanguinea_, belonging to the family Cicadidæ,
+is used like the Meloidæ, to produce blistering, and often causes
+poisoning. It has been assumed that its vescicating properties are due
+to cantharidin, but the presence of this substance has not been
+demonstrated.
+
+Certain Aphididæ contain a strongly irritating substance which produces,
+not merely on mucous membranes but on outer skin, a characteristic
+inflammation.
+
+It has been frequently reported that the larvæ of the European cabbage
+butterfly, _Pieris brassicæ_, accidentally eaten by cows, horses, ducks,
+and other domestic animals, cause severe colic, attempts to vomit,
+paralysis of the hind legs, salivation, and stomatitis. On _postmortem_
+there are to be found hæmorrhagic gastro-enteritis, splenitis, and
+nephritis. Kobert has recently investigated the subject and has found a
+poisonous substance in the blood of not only the larvæ but also the
+pupæ.
+
+
+FOOTNOTES:
+
+[A] This is diametrically opposed to the findings of Bordas (1905) in
+the case of the European _Latrodectus 13-guttatus_, whose glands are
+"much larger than those of other spiders." From a considerable
+comparative study, we should also unhesitatingly make this statement
+regarding the glands of our American species, _L. mactans_.
+
+[B] Dr. E. H. Coleman (Kellogg, 1915) has demonstrated its virulence by
+a series of experiments comparable with those of Kobert.
+
+[C] According to Stiles, the species occurring in the Northwest which is
+commonly identified as _D. venustus_ should be called _D. andersoni_
+(see footnote, chapter 12).
+
+[D] It should be remembered that in all the higher Hymenoptera the first
+abdominal segment is fused with the thorax and that what is apparently
+the sixth segment is, in reality, the seventh.
+
+
+
+
+CHAPTER III
+
+PARASITIC ARTHROPODA AFFECTING MAN
+
+
+The relation of insects to man as simple parasites has long been
+studied, and until very recent years the bulk of the literature of
+medical entomology referred to this phase of the subject. This is now
+completely overshadowed by the fact that so many of these parasitic
+forms are more than simple parasites, they are transmitters of other
+microscopic parasites which are pathogenic to man. Yet the importance of
+insects as parasites still remains and must be considered in a
+discussion of the relation of insects to the health of man. In taking up
+the subject we shall first consider some general features of the
+phenomenon of animal parasitism.
+
+Parasitism is an adaptation which has originated very often among living
+organisms and in widely separated groups. It would seem simple to define
+what is meant by a "parasite" but, in reality, the term is not easily
+limited. It is often stated that a parasite is "An organism which lives
+at the expense of another," but this definition is applicable to a
+predatory species or, in its broadest sense, to all organisms. For our
+purpose we may say with Braun: "A parasite is an organism which, for the
+purpose of obtaining food, takes up its abode, temporarily or
+permanently, on or within another living organism".
+
+Thus, parasitism is a phase of the broad biological phenomenon of
+_symbiosis_, or living together of organisms. It is distinguished from
+_mutualism_, or symbiosis in the narrow sense, by the fact that only one
+party to the arrangement obtains any advantage, while the other is to a
+greater or less extent injured.
+
+Of parasites we may distinguish on the basis of their location on or in
+the host, _ecto-parasites_, which live outside of the body; and
+_endoparasites_, which live within the body. On account of their method
+of breathing the parasitic arthropods belong almost exclusively to the
+first of these groups.
+
+On the basis of relation to their host, we find _temporary parasites_,
+those which seek the host only occasionally, to obtain food; and the
+_stationary_ or _permanent_ parasites which, at least during certain
+stages, do not leave their host.
+
+_Facultative parasites_ are forms which are not normally parasitic, but
+which, when accidentally ingested, or otherwise brought into the body,
+are able to exist for a greater or less period of time in their unusual
+environment. These are generally called in the medical literature
+"pseudoparasites" but the term is an unfortunate one.
+
+We shall now take up the different groups of arthropods, discussing the
+more important of the parasitic forms attacking man. The systematic
+relationship of these forms, and key for determining important species
+will be found in Chapter XII.
+
+
+ACARINA OR MITES
+
+The ACARINA, or _mites_, form a fairly natural group of arachnids,
+characterized, in general, by a sac-like, unsegmented body which is
+generally fused with the cephalothorax. The mouth-parts have been united
+to form a beak or rostrum.
+
+The representatives of this group undergo a marked metamorphosis.
+Commonly, the larvæ on hatching from the egg, possess but three pairs of
+legs, and hence are called _hexapod larvæ_. After a molt, they transform
+into nymphs which, like the adult, have four pairs of legs and are
+called _octopod nymphs_. These after a period of growth, molt one or
+more times and, acquiring external sexual organs, become adult.
+
+Most of the mites are free-living, but there are many parasitic species
+and as these have originated in widely separated families, the Acarina
+form an especially favorable group for study of the origin of
+parasitism. Such a study has been made by Ewing (1911), who has reached
+the following conclusions:
+
+"We have strong evidence indicating that the parasitic habit has
+originated independently at least eleven times in the phylogeny of the
+Ararina. Among the zoophagous parasites, the parasitic habit has been
+developed from three different types of free-living Acarina: (a)
+predaceous forms, (b) scavengers, (c) forms living upon the juices of
+plants."
+
+Ewing also showed that among the living forms of Acarina we can trace
+out all the stages of advancing parasitism, semiparasitism, facultative
+parasitism, even to the fixed and permanent type, and finally to
+endoparasitism.
+
+Of the many parasitic forms, there are several species which are serious
+parasites of man and we shall consider the more important of these.
+Infestation by mites is technically known as _acariasis_.
+
+[Illustration: 43. Effect of the harvest mites on the skin of man.
+Photograph by J. C. Bradley.]
+
+
+The Trombidiidæ, or Harvest Mites
+
+In many parts of this country it is impossible for a visitor to go into
+the fields and, particularly, into berry patches and among tall weeds
+and grass in the summer or early fall without being affected by an
+intolerable itching, which is followed, later, by a breaking out of
+wheals, or papules, surrounded by a bright red or violaceous aureola,
+(fig. 43). It is often regarded as a urticaria or eczema, produced by
+change of climate, an error in diet, or some condition of general
+health.
+
+Sooner or later, the victim finds that it is due to none of these, but
+to the attacks of an almost microscopic red mite, usually called
+"jigger" or "chigger" in this country. As the term "chigger" is applied
+to one of the true fleas, _Dermatophilus penetrans_, of the tropics,
+these forms are more correctly known as "harvest mites." Natives of an
+infested region may be so immune or accustomed to its attacks as to be
+unaware of its presence, though such immunity is by no means possessed
+by all who have been long exposed to the annoyance.
+
+[Illustration: 44. Harvest mites. (Larvæ of Trombidium). After C. V.
+Riley.]
+
+The harvest mites, or chiggers, attacking man are larval forms,
+possessing three pairs of legs (fig. 44). Their systematic position was
+at first unknown and they were classed under a special genus _Leptus_, a
+name which is very commonly still retained in the medical literature. It
+is now known that they are the larval forms of various species of the
+genus _Trombidium_, a group of predaceous forms, the adults of which
+feed primarily on insects and their eggs. In this country the species
+best known are those to be found late in summer, as larvæ at the base of
+the wings of houseflies or grasshoppers.
+
+There is much uncertainty as to the species of the larvæ attacking man
+but it is clear that several are implicated. Bruyant has shown that in
+France the larvæ _Trombidium inapinatum_ and _Trombidium holosericeum_
+are those most frequently found. The habit of attacking man is abnormal
+and the larvæ die after entering the skin. Normally they are parasitic
+on various insects.
+
+Most recent writers agree that, on man, they do not bore into the skin,
+as is generally supposed, but enter a hair follicle or sebaceous gland
+and from the bottom of this, pierce the cutis with their elongate
+hypopharynx. According to Braun, there arises about the inserted
+hypopharynx a fibrous secretion--the so-called "beak" which is, in
+reality, a product of the host. Dr. J. C. Bradley, however, has made
+careful observations on their method of attack, and he assures us that
+the mite ordinarily remains for a long time feeding on the surface of
+the skin, where it produces the erythema above described. During this
+time it is not buried in the skin but is able to retreat rapidly into it
+through a hair follicle or sweat gland. The irritation from the mites
+ceases after a few days, but not infrequently the intolerable itching
+leads to so much scratching that secondary infection follows.
+
+Relief from the irritation may be afforded by taking a warm salt bath as
+soon as possible after exposure or by killing the mites by application
+of benzine, sulphur ointment or carbolized vaseline. When they are few
+in number, they can be picked out with a sterile needle.
+
+Much may be done in the way of warding off their attacks by wearing
+gaiters or close-woven stockings extending from ankle to the knee. Still
+more efficacious is the sprinkling of flowers of sulphur in the
+stockings and the underclothes from a little above the knee, down. The
+writers have known this to make it possible for persons who were
+especially susceptible to work with perfect comfort in badly infested
+regions. Powdered naphthalene is successfully used in the same way and
+as Chittenden (1906) points out, is a safeguard against various forms of
+man-infesting tropical insect pests.
+
+The question of the destruction of the mites in the field is sometimes
+an important one, and under some conditions, is feasible. Chittenden
+states that much can be accomplished by keeping the grass, weeds, and
+useless herbage mowed closely, so as to expose the mites to the sun. He
+believes that in some cases good may be done by dusting the grass and
+other plants, after cutting, with flowers of sulphur or by spraying with
+dilute kerosene emulsion in which sulphur has been mixed. More recently
+(1914) he calls attention to the value of cattle, and more especially
+sheep, in destroying the pests by tramping on them and by keeping the
+grass and herbage closely cropped.
+
+
+IXODOIDEA OR TICKS
+
+Until recently, the ticks attracted comparatively little attention from
+entomologists. Since their importance as carriers of disease has been
+established, interest in the group has been enormously stimulated and
+now they rank second only to the mosquitoes in the amount of detailed
+study that has been devoted to them.
+
+[Illustration: 45_a_. Argus persicus. Capitulum of male. After Nuttall
+and Warburton.]
+
+The ticks are the largest of the Acarina. They are characterized by the
+fact that the hypostome, or "tongue" (fig. 45) is large and file-like,
+roughened by sharp teeth. They possess a breathing pore on each side of
+the body, above the third or fourth coxæ (fig. 45_b_).
+
+[Illustration: 45_b_. Left spiracle of nymph of _Argas persicus_. After
+Nuttall and Warburton.]
+
+There are two distinct families of the IXODOIDEA, differing greatly in
+structure, life-history and habits. These are the ARGASIDÆ and the
+IXODIDÆ. We shall follow Nuttall (1908) in characterizing these two
+families and in pointing out their biological differences, and shall
+discuss briefly the more important species which attack man. The
+consideration of the ticks as carriers of disease will be reserved for a
+later chapter.
+
+
+Argasidæ
+
+In the ticks belonging to the family ARGASIDÆ, there is comparatively
+little sexual dimorphism, while this is very marked in the Ixodidæ. The
+capitulum, or so-called "head" is ventral, instead of terminal; the
+palpi are leg-like, with the segments subequal; the scutum, or dorsal
+shield, is absent; eyes, when present, are lateral, on supracoxal folds.
+The spiracles are very small; coxæ unarmed; tarsi without ventral
+spurs, and the pulvilli are absent or rudimentary.
+
+In habits and life history the Argasidæ present striking
+characteristics. In the first place, they are long-lived, a factor which
+counts for much in the maintenance of the species. They are intermittent
+feeders, being comparable with the bed-bug in this respect. There are
+two or more nymphal stages, and they may molt after attaining maturity.
+The female lays comparatively few eggs in several small batches.
+
+Nuttall (1911) concludes that "The Argasidæ represent the relatively
+primitive type of ticks because they are less constantly parasitic than
+are the Ixodidæ. Their nymphs and adults are rapid feeders and chiefly
+infest the habitat of their hosts. * * * Owing to the Argasidæ infesting
+the habitats of their hosts, their resistance to prolonged starvation
+and their rapid feeding habits, they do not need to bring forth a large
+progeny, because there is less loss of life in the various stages, as
+compared with the Ixodidæ, prior to their attaining maturity."
+
+[Illustration: 46. Argus persicus. Dorsal and ventral aspects. (×4).
+After Hassell.]
+
+Of the Argasidæ, we have in the United States, several species which
+have been reported as attacking man.
+
+_Argas persicus_, the famous "Miana bug" (fig. 46), is a very widely
+distributed species, being reported from Europe, Asia, Africa, and
+Australia. It is everywhere preeminently a parasite of fowls. According
+to Nuttall it is specifically identical with _Argas americanus_ Packard
+or _Argas miniatus_ Koch, which is commonly found on fowls in the United
+States, in the South and Southwest. Its habits are comparable to those
+of the bed-bug. It feeds intermittently, primarily at night, and instead
+of remaining on its host, it then retreats to cracks and crevices.
+Hunter and Hooker (1908) record that they have found the larva to remain
+attached for five or eight days before dropping. Unlike the Ixodidæ, the
+adults oviposit frequently.
+
+[Illustration: 47. Otiobius (Ornithodoros) megnini, head of nymph. After
+Stiles.]
+
+[Illustration: 48. Otiobius (Ornithodoros) megnini, male. (_a_) dorsal,
+(_b_) ventral aspect. After Nuttall and Warburton.]
+
+The most remarkable feature of the biology of this species is the great
+longevity, especially of the adult. Hunter and Hooker report keeping
+larvæ confined in summer in pill boxes immediately after hatching for
+about two months while under similar conditions those of the Ixodid,
+_Boophilus annulatus_ lived for but two or three days. Many writers have
+recorded keeping adults for long periods without food. We have kept
+specimens in a tin box for over a year and a half and at the end of that
+time a number were still alive. Laboulliene kept unfed adults for over
+three years. In view of the effectiveness of sulphur in warding off the
+attacks of Trombidiidæ, it is astonishing to find that Lounsbury has
+kept adults of _Argas persicus_ for three months in a box nearly filled
+with flowers of sulphur, with no apparent effect on them.
+
+We have already called attention to the occasional serious effects of
+the bites of this species. While such reports have been frequently
+discredited there can be no doubt that they have foundation in fact. The
+readiness with which this tick attacks man, and the extent to which old
+huts may be infested makes it especially troublesome.
+
+_Otiobius (Ornithodoros) megnini_, the "spinose ear-tick" (figs. 47,
+48), first described from Mexico, as occurring in the ears of horses, is
+a common species in our Southwestern States and is recorded by Banks as
+occurring as far north as Iowa.
+
+The species is remarkable for the great difference between the spiny
+nymph stage and the adult. The life history has been worked out by
+Hooker (1908). Seed ticks, having gained entrance to the ear, attach
+deeply down in the folds, engorge, and in about five days, molt; as
+nymphs with their spinose body they appear entirely unlike the larvæ. As
+nymphs they continue feeding sometimes for months. Finally the nymph
+leaves the host, molts to form the unspined adult, and without further
+feeding is fertilized and commences oviposition.
+
+The common name is due to the fact that in the young stage the ticks
+occur in the ear of their hosts, usually horses or cattle. Not
+uncommonly it has been reported as occurring in the ear of man and
+causing very severe pain. Stiles recommends that it be removed by
+pouring some bland oil into the ear.
+
+Banks (1908) reports three species of _Ornithodoros_--_O. turicata_,
+_coriaceus_ and _talaje_--as occurring in the United States. All of these
+attack man and are capable of inflicting very painful bites.
+
+
+Ixodidæ
+
+The ticks belonging to the family IXODIDÆ (figs. 49 and 50) exhibit a
+marked sexual dimorphism. The capitulum is anterior, terminal, instead
+of ventral as in the Argasidæ; the palpi are relatively rigid (except in
+the subfamily Ixodinæ), with rudimentary fourth segment; scutum present;
+eyes, when present, dorsal, on side of scutum. The spiracles are
+generally large, situated well behind the fourth coxæ; coxæ generally
+with spurs; pulvilli always present.
+
+In habits and life history the typical Ixodidæ differ greatly from the
+Argasidæ. They are relatively short-lived, though some recent work
+indicates that their longevity has been considerably under-estimated.
+Typically, they are permanent feeders, remaining on the host, or hosts,
+during the greater part of their life. They molt twice only, on leaving
+the larval and the nymphal stages. The adult female deposits a single,
+large batch of eggs. Contrasting the habits of the Ixodidæ to those of
+the Argasidæ, Nuttall (1911) emphasizes that the Ixodidæ are more highly
+specialized parasites. "The majority are parasitic on hosts having no
+fixed habitat and consequently all stages, as a rule, occur upon the
+host."
+
+[Illustration: 49. Ixodes ricinus; male, ventral aspect. After Braun and
+Luehe.]
+
+As mere parasites of man, apart from their power to transmit disease,
+the Ixodidæ are much less important than the Argasidæ. Many are reported
+as occasionally attacking man and of these the following native species
+may be mentioned.
+
+[Illustration: 50. Ixodes ricinus, var. scapularis, female. Capitulum
+and scutum; ventral aspect of capitulum; coxæ; tarsus 4; spiracle;
+genital and anal grooves. After Nuttall and Warburton.]
+
+_Ixodes ricinus_, the European castor bean tick (figs. 49, 50), is a
+species which has been often reported from this country but Banks (1908)
+has shown that, though it does occur, practically all of the records
+apply to _Ixodes scapularis_ or _Ixodes cookei_. In Europe, _Ixodes
+ricinus_ is very abundant and very commonly attacks man. At the point
+of penetration of the hypostome there is more or less inflammation but
+serious injury does not occur unless there have been introduced
+pathogenic bacteria or, unless the tick has been abruptly removed,
+leaving the capitulum in the wound. Under the latter circumstances,
+there may be an abscess formed about the foreign body and occasionally,
+serious results have followed. Under certain conditions the tick, in
+various stages, may penetrate under the skin and produce a tumor, within
+which it may survive for a considerable period of time.
+
+_Ixodes cookei_ is given by Banks as "common on mammals in the Eastern
+States as far west as the Rockies." It is said to affect man severely.
+
+_Amblyomma americanum_, (fig. 158c), the "lone star tick," is widely
+distributed in the United States. Its common name is derived from the
+single silvery spot on the scutum of the female. Hunter and Hooker
+regard this species as, next to _Boophilus annulatus_, the most
+important tick in the United States. Though more common on cattle, it
+appears to attack mammals generally, and "in portions of Louisiana and
+Texas it becomes a pest of considerable importance to moss gatherers and
+other persons who spend much time in the forests."
+
+_Amblyomma cajennense_, noted as a pest of man in central and tropical
+America, is reported from various places in the south and southwestern
+United States.
+
+_Dermacentor variabilis_ is a common dog tick of the eastern United
+States. It frequently attacks man, but the direct effects of its bite
+are negligible.
+
+The "Rocky Mountain spotted fever tick" (_Dermacentor andersoni_
+according to Stiles, _D. venustus_ according to Banks) is, from the
+viewpoint of its effects on man, the most important of the ticks of the
+United States. This is because, as has been clearly established, it
+transmits the so-called "spotted fever" of man in our northwestern
+states. This phase of the subject will be discussed later and it need
+merely be mentioned here, that this species has been reported as causing
+painful injuries by its bites. Dr. Stiles states that he has seen cases
+of rather severe lymphangitis and various sores and swellings developing
+from this cause. In one case, of an individual bitten near the elbow,
+the arm became very much swollen and the patient was confined in bed for
+several days. The so-called tick paralysis produced by this species is
+discussed in a preceding chapter.
+
+There are many other records of various species of ticks attacking man,
+but the above-mentioned will serve as typical and it is not necessary to
+enter into greater detail.
+
+
+TREATMENT OF TICK BITES--When a tick attaches to man the first thing to
+be done is to remove it without leaving the hypostome in the wound to
+fester and bring about secondary effects. This is best accomplished by
+applying to the tick's body some substance which will cause it to more
+readily loosen its hold. Gasoline or petroleum, oil or vaseline will
+serve. For removing the spinose ear-tick, Stiles recommends pouring some
+bland oil into the ear. Others have used effectively a pledget of cotton
+soaked in chloroform.
+
+In general, the treatment recommended by Wellman for the bites of
+_Ornithodoros moubata_ will prove helpful. It consists of prolonged
+bathing in very hot water, followed by the application of a strong
+solution of bicarbonate of soda, which is allowed to dry upon the skin.
+He states that this treatment is comforting. For severe itching he
+advises smearing the bites with vaseline, which is slightly impregnated
+with camphor or menthol. Medical aid should be sought when complications
+arise.
+
+The DERMANYSSIDÆ are Gamasid mites which differ from others of the group
+in that they are parasitic on vertebrates. None of the species normally
+attack man, but certain of them, especially the poultry mite, may be
+accidental annoyances.
+
+[Illustration: 51. Dermanyssus gallinæ, female. After Delafond.]
+
+_Dermanyssus gallinæ_ (fig. 51), the red mite of poultry, is an
+exceedingly common and widespread parasite of fowls. During the day it
+lives in cracks and crevices of poultry houses, under supports of
+roosts, and in litter of the food and nests, coming out at night to
+feed. They often attack people working in poultry houses or handling
+and plucking infested fowls. They may cause an intense pruritis, but
+they do not produce a true dermatosis, for they do not find conditions
+favorable for multiplication on the skin of man.
+
+
+Tarsonemidæ
+
+The representatives of the family TARSONEMIDÆ are minute mites, with the
+body divided into cephalothorax and abdomen. There is marked sexual
+dimorphism. The females possess stigmata at the anterior part of the
+body, at the base of the rostrum, and differ from all other mites in
+having on each side, a prominent clavate organ between the first and
+second legs. The larva, when it exists, is hexapodous and resembles the
+adult. A number of the species are true parasites on insects, while
+others attack plants. Several of them may be accidental parasites of
+man.
+
+[Illustration: 52. Pediculoides ventricosus, female. After Webster.]
+
+[Illustration: 53. Pediculoides ventricosus, gravid female. (×80).
+After Webster.]
+
+_Pediculoides ventricosus_ (fig. 52 and 53) is, of all the Tarsonemidæ
+reported, the one which has proved most troublesome to man. It is a
+predaceous species which attacks a large number of insects but which has
+most commonly been met with by man through its fondness for certain
+grain-infesting insects, notably the Angoumois grain moth, _Sitotroga
+cerealella_, and the wheat straw-worm, _Isosoma grande_. In recent years
+it has attracted much attention in the United States and its
+distribution and habits have been the object of detailed study by
+Webster (1901).
+
+[Illustration: 54. Pediculoides ventricosus, male. After Braun.]
+
+There is a very striking sexual dimorphism in this species. The
+non-gravid female is elongate, about 200µ by 70µ (fig. 52), with the
+abdomen slightly striated longitudinally. The gravid female (fig. 53)
+has the abdomen enormously swollen, so that it is from twenty to a
+hundred times greater than the rest of the body. The species is
+viviparous and the larvæ undergo their entire growth in the body of the
+mother. They emerge as sexually mature males and females which soon
+pair. The male (fig. 54) is much smaller, reaching a length of only 320µ
+but is relatively broad, 80µ, and angular. Its abdomen is very greatly
+reduced.
+
+As far back as 1850 it was noted as causing serious outbreaks of
+peculiar dermatitis among men handling infested grain. For some time the
+true source of the difficulty was unknown and it was even believed that
+the grain had been poisoned. Webster has shown that in this country (and
+probably in Europe as well) its attacks have been mistaken for those of
+the red bugs or "chiggers" (larval Trombiidæ). More recently a number of
+outbreaks of a mysterious "skin disease" were traced to the use of straw
+mattresses, which were found to be swarming with these almost
+microscopic forms which had turned their attentions to the occupants of
+the beds. Other cases cited were those of farmers running wheat through
+a fanning mill, and of thrashers engaged in feeding unthrashed grain
+into the cylinder of the machine.
+
+[Illustration: 55. Lesions produced by the attacks of Pediculoides
+ventricosus. After Webster.]
+
+The medical aspects of the question have been studied especially by
+Schamberg and Goldberger and from the latter's summary (1910) we derive
+the following data. Within twelve to sixteen hours after exposure,
+itching appears and in severe cases, especially where exposure is
+continued night after night by sleeping on an infested bed, the itching
+may become almost intolerable. Simultaneously, there appears an eruption
+which characteristically consists of wheals surrounded by a vesicle
+(fig. 55). The vesicle as a rule does not exceed a pin head in size but
+may become as large as a pea. Its contents rapidly become turbid and in
+a few hours it is converted into a pustule. The eruption is most
+abundant on the trunk, slight on the face and extremities and almost
+absent on the feet and hands. In severe cases there may be
+constitutional disturbances marked, at the outset, by chilliness,
+nausea, and vomiting, followed for a few days by a slight elevation of
+temperature, with the appearance of albumin in the urine. In some cases
+the eruption may simulate that of chicken-pox or small-pox.
+
+Treatment for the purpose of killing the mites is hardly necessary as
+they attach feebly to the surface and are readily brushed off by
+friction of the clothes. "Antipruritic treatment is always called for;
+warm, mildly alkaline baths or some soothing ointment, such as zinc
+oxide will be found to fulfil this indication." Of course, reinfestation
+must be guarded against, by discarding, or thoroughly fumigating
+infested mattresses, or by avoiding other sources. Goldberger suggests
+that farm laborers who must work with infested wheat or straw might
+protect themselves by anointing the body freely with some bland oil or
+grease, followed by a change of clothes and bath as soon as their work
+is done. We are not aware of any experiments to determine the effect of
+flowers of sulphur, but their efficiency in the case of "red bugs"
+suggests that they are worth a trial against _Pediculoides_.
+
+Various species of TYROGLYPHIDÆ (fig. 150_f_) may abound on dried fruits
+and other products and attacking persons handling them, may cause a
+severe dermatitis, comparable to that described above for _Pediculoides
+ventricosus_. Many instances of their occurrence as such temporary
+ectoparasites are on record. Thus, workers who handle vanilla pods are
+subject to a severe dermatitis, known as vanillism, which is due to the
+attacks of _Tyroglyphus siro_, or a closely related species. The
+so-called "grocer's itch" is similarly caused by mites infesting various
+products. Castellani has shown that in Ceylon, workers employed in the
+copra mills, where dried cocoanut is ground up for export, are much
+annoyed by mites, which produce the so-called "copra itch." The skin of
+the hands, arms and legs, and sometimes of the whole body, except the
+face, is covered by fairly numerous, very pruriginous papules, often
+covered by small, bloody crusts due to scratching. The condition is
+readily mistaken for scabies. It is due to the attacks of _Tyroglyphus
+longior castellanii_ which occur in enormous numbers in some samples of
+the copra.
+
+
+Sarcoptidæ
+
+The SARCOPTIDÆ are minute whitish mites, semi-globular in shape, with a
+delicate transversely striated cuticula. They lack eyes and tracheæ. The
+mouth-parts are fused at the base to form a cone which is usually
+designated as the head. The legs are short and stout, and composed of
+five segments. The tarsi may or may not possess a claw and may terminate
+in a pedunculated sucker, or simple long bristle, or both. The presence
+or absence of these structures and their distribution are much used in
+classification. The mites live on or under the skin of mammals and
+birds, where they produce the disease known as scabies, mange, or itch.
+Several species of the Sarcoptidæ attack man but the most important of
+these, and the one pre-eminent as the "itch mite" is _Sarcoptes
+scabiei_.
+
+The female of _Sarcoptes scabiei_, of man, is oval and yellowish white;
+the male more rounded and of a somewhat reddish tinge, and much smaller.
+The body is marked by transverse striæ which are partly interrupted on
+the back. There are transverse rows of scales, or pointed spines, and
+scattered bristles on the dorsum.
+
+[Illustration: 56_a_. Sarcoptes scabiei, male. (×100). After
+Fürstenberg.]
+
+The male (fig. 56) which is from 200-240µ in length, and 150-200µ in
+breadth, possesses pedunculated suckers on each pair of legs except the
+third, which bears, instead, a long bristle. The female (fig. 56)
+300-450µ in length and 250-350µ in breadth, has the pedunculated suckers
+on the first and second pairs of legs, only, the third and fourth
+terminating in bristles.
+
+[Illustration: 56_b_. Sarcoptes scabiei, female. (×100.) After
+Fürstenberg.]
+
+The mite lives in irregular galleries from a few millimeters to several
+centimeters in length, which it excavates in the epidermis (fig. 57). It
+works especially where the skin is thin, such as between the fingers, in
+the bend of the elbows and knees, and in the groin, but it is by no
+means restricted to these localities. The female, alone, tunnels into
+the skin; the males remain under the superficial epidermal scales, and
+seldom are found, as they die soon after mating.
+
+As she burrows into the skin the female deposits her eggs, which measure
+about 150 × 100µ. Fürstenberg says that each deposits an average of
+twenty-two to twenty-four eggs, though Gudden reports a single burrow as
+containing fifty-one. From these there develop after about seven days,
+the hexapod larvæ. These molt on the sixteenth day to form an octopod
+nymph, which molts again the twenty-first day. At the end of the fourth
+week the nymphs molt to form the sexually mature males and the so-called
+pubescent females. These pair, the males die, and the females again cast
+their skin, and become the oviparous females. Thus the life cycle is
+completed in about twenty-eight days.
+
+The external temperature exercises a great influence on the development
+of the mites and thus, during the winter, the areas of infestation not
+only do not spread, but they become restricted. As soon as the
+temperature rises, the mites increase and the infestation becomes much
+more extensive.
+
+[Illustration: 57. Sarcoptes scabiei. Diagrammatic representation of the
+course in the skin of man.]
+
+In considering the possible sources of infestation, and the chances of
+reinfestation after treatment, the question of the ability of the mite
+to live apart from its host is a very important one. Unfortunately there
+are few reliable data on this subject. Gerlach found that, exposed in
+the dry, warm air of a room they became very inactive within twenty-four
+hours, that after two days they showed only slight movement, and that
+after three or four days they could not be revived by moisture and
+warming. The important fact was brought out that in moist air, in folded
+soiled underwear, they survived as long as ten days. Bourguignon found
+that under the most favorable conditions the mites of _Sarcoptes scabiei
+equi_ would live for sixteen days.
+
+The disease designated the "itch" or "scabies," in man has been known
+from time immemorial, but until within less than a hundred years it was
+almost universally attributed to malnutrition, errors of diet, or "bad
+blood." This was in spite of the fact that the mite was known to Mouffet
+and that Bonomo had figured both the adult and the egg and had declared
+the mite the sole cause of the disease. In 1834 the Corsican medical
+student, Francis Renucci, demonstrated the mite before a clinic in Saint
+Louis Hospital in Paris and soon thereafter there followed detailed
+studies of the life history of the various itch mites of man and
+animals.
+
+[Illustration: 58. Scabies on the hand. From portfolio of Dermochromes
+by permission of Rebman & Co., of New York. Publishers.]
+
+The disease is a cosmopolitan one, being exceedingly abundant in some
+localities. Its spread is much favored where large numbers of people are
+crowded together under insanitary conditions and hence it increases
+greatly during wars and is widely disseminated and abundant immediately
+afterwards. Though more commonly to be met with among the lower classes,
+it not infrequently appears among those of the most cleanly, careful
+habits, and it is such cases that are most liable to wrong diagnosis by
+the physician.
+
+Infection occurs solely through the passage, direct or indirect, of the
+young fertilized females to the skin of a healthy individual. The adult,
+oviparous females do not quit their galleries and hence do not serve to
+spread the disease. The young females move about more or less at night
+and thus the principal source of infestation is through sleeping in the
+same bed with an infested person, or indirectly through bedclothes, or
+even towels or clothing. Diurnal infestation through contact or clothing
+is exceptional. Many cases are known of the disease being contracted
+from animals suffering from scabies, or mange.
+
+When a person is exposed to infestation, the trouble manifests itself
+after eight or ten days, though there usually elapses a period of twenty
+to thirty days before there is a suspicion of anything serious. The
+first symptom is an intense itching which increases when the patient is
+in bed. When the point of irritation is examined the galleries may
+usually be seen as characteristic sinuous lines, at first whitish in
+color but soon becoming blackish because of the contained eggs and
+excrement. The galleries, which may not be very distinct in some cases,
+may measure as much as four centimeters in length. Little vesicles, of
+the size of a pin head are produced by the secretions of the feeding
+mite; they are firm, and projecting, and contain a limpid fluid. Figures
+58 and 59 show the typical appearance of scabies on the hands, while
+figure 60 shows a severe general infestation. The intolerable itching
+induces scratching and through this various complications may arise. The
+lesions are not normally found on the face and scalp, and are rare on
+the back.
+
+[Illustration: 59. Scabies on the hand. After Duhring.]
+
+[Illustration: 60. Generalized infection of Scabies. After Morrow.]
+
+Formerly, scabies was considered a very serious disease, for its cause
+and method of treatment were unknown, and potentially it may continue
+indefinitely. Generation after generation of the mites may develop and
+finally their number become so great that the general health of the
+individual is seriously affected. Now that the true cause of the disease
+is known, it is easily controlled.
+
+Treatment usually consists in softening the skin by friction with soap
+and warm water, followed by a warm bath, and then applying some
+substance to kill the mites. Stiles gives the following directions,
+modified from Bourguignon's, as "a rather radical guide, to be modified
+according to facilities and according to the delicacy of the skin or
+condition of the patient":
+
+1. The patient, stripped naked, is energetically rubbed all over (except
+the head) for twenty minutes, with green soap and warm water. 2. He is
+then placed in a warm bath for thirty minutes, during which time the
+rubbing is continued. 3. The parasiticide is next rubbed in for twenty
+minutes and is allowed to remain on the body for four or five hours; in
+the meantime the patient's clothes are sterilized, to kill the eggs or
+mites attached to them. 4. A final bath is taken to remove the
+parasiticide.
+
+The parasiticide usually relied on is the officinal sulphur ointment of
+the United States pharmacopoeia. When infestation is severe it is
+necessary to repeat treatment after three or four days in order to kill
+mites which have hatched from the eggs.
+
+The above treatment is too severe for some individuals and may, of
+itself, produce a troublesome dermatitis. We have seen cases where the
+treatment was persisted in and aggravated the condition because it was
+supposed to be due to the parasite. For delicate-skinned patients the
+use of balsam of Peru is very satisfactory, and usually causes no
+irritation whatever. Of course, sources of reinfection should be
+carefully guarded against.
+
+_Sarcoptes scabiei crustosæ_, which is a distinct variety, if not
+species, of the human itch mite, is the cause of so-called Norwegian
+itch. This disease is very contagious, and is much more resistant than
+the ordinary scabies. Unlike the latter, it may occur on the face and
+scalp.
+
+_Sarcoptes scabiei_ not only attacks man but also occurs on a large
+number of mammals. Many species, based on choice of host, and minute
+differences in size and secondary characters, have been established, but
+most students of the subject relegate these to varietal rank. Many of
+them readily attack man, but they have become sufficiently adapted to
+their normal host so that they are usually less persistent on man.
+
+_Notoedres cati_ (usually known as _Sarcoptes minor_) is a species of
+itch mites which produce an often fatal disease of cats. The body is
+rounded and it is considerably smaller than _Sarcoptes scabiei_, the
+female (fig. 61) measuring 215-230µ long and 165-175µ wide; the males
+145-150µ by 120-125µ. The most important character separating
+_Notoedres_ from _Sarcoptes_ is the position of the anus, which is
+dorsal instead of terminal. The mite readily transfers to man but does
+not persist, the infestation usually disappearing spontaneously in about
+two weeks. Infested cats are very difficult to cure, unless treatment is
+begun at the very inception of the outbreak, and under ordinary
+circumstances it is better to kill them promptly, to avoid spread of the
+disease to children and others who may be exposed.
+
+[Illustration: 61. Notoedres cati, male and female. After Railliet.]
+
+
+Demodecidæ
+
+The DEMODECIDÆ are small, elongate, vermiform mites which live in the
+hair follicles of mammals. The family characteristics will be brought
+out in the discussion of the species infesting man, _Demodex
+folliculorum_.
+
+[Illustration: 62. Demodex folliculorum. (×200) After Blanchard.]
+
+_Demodex folliculorum_ (fig. 62) is to be found very commonly in the
+hair follicles and sebaceous glands of man. It is vermiform in
+appearance, and with the elongate abdomen transversely striated so as to
+give it the appearance of segmentation. The female is 380-400µ long by
+45µ; the male 300µ by 40µ. The three-jointed legs, eight in number, are
+reduced to mere stubs in the adult. The larval form is hexopod. These
+mites thus show in their form a striking adaptation to their
+environment. In the sebaceous glands and hair follicles they lie with
+their heads down (fig. 63). Usually there are only a few in a gland, but
+Gruby has counted as many as two hundred.
+
+[Illustration: 63. Demodex folliculorum. Section through skin showing
+the mites in situ. Magnification of Nos. 1, 2, 6 and 7, ×150; Nos, 3,
+4, 5, ×450. After Megnin.]
+
+The frequency with which they occur in man is surprising. According to
+European statistics they are found in 50 per cent to 60 per cent or even
+more. Gruby found them in forty out of sixty persons examined. These
+figures are very commonly quoted, but reliable data for the United
+States seem to be lacking. Our studies indicate that it is very much
+less common in this country than is generally assumed.
+
+The Demodex in man does not, as a rule, cause the slightest
+inconvenience to its host. It is often stated that they give rise to
+comedons or "black-heads" but there is no clear evidence that they are
+ever implicated. Certain it is that they are not the usual cause. A
+variety of the same, or a very closely related species of _Demodex_, on
+the dog gives rise to the very resistant and often fatal follicular
+mange.
+
+
+HEXAPODA OR TRUE INSECTS
+
+The HEXAPODA, or true insects, are characterized by the fact that the
+adult possesses three pairs of legs. The body is distinctly segmented
+and is divided into head, thorax, and abdomen.
+
+The mouth-parts in a generalized form, consist of an upper lip, or
+_labrum_, which is a part of the head capsule, and a central unpaired
+_hypopharynx_, two _mandibles_, two _maxillæ_ and a lower lip, or
+_labium_, made up of the fused pair of second maxillæ. These parts may
+be greatly modified, dependent upon whether they are used for biting,
+sucking, piercing and sucking, or a combination of biting and sucking.
+
+Roughly speaking, insects may be grouped into those which undergo
+_complete metamorphosis_ and those which have _incomplete
+metamorphosis_. They are said to undergo complete metamorphosis when the
+young form, as it leaves the egg, bears no resemblance to the adult. For
+example, the maggot changes to a quiescent pupa and from this emerges
+the winged active fly. They undergo incomplete metamorphosis, when the
+young insect, as it leaves the egg, resembles the adult to a greater or
+less extent, and after undergoing a certain number of molts becomes
+sexually mature.
+
+Representatives of several orders have been reported as accidental or
+faculative parasites of man, but the true parasites are restricted to
+four orders. These are the Siphunculata; the Hemiptera, the Diptera and
+the Siphonaptera.
+
+
+SIPHUNCULATA
+
+The order SIPHUNCULATA was established by Meinert to include the true
+sucking lice. These are small wingless insects, with reduced
+mouth-parts, adapted for sucking; thorax apparently a single piece due
+to indistinct separation of its three segments: the compound eyes
+reduced to a single ommatidium on each side. The short, powerful legs
+are terminated by a single long claw. Metamorphosis incomplete.
+
+There has been a great deal of discussion regarding the structure of the
+mouth-parts, and the relationships of the sucking lice, and the
+questions cannot yet be regarded as settled. The conflicting views are
+well represented by Cholodkovsky (1904 and 1905) and by Enderlein
+(1904).
+
+[Illustration: 64. Pediculus showing the blind sac (_b_) containing the
+mouth parts (_a_) beneath the alimentary canal (_p_). After Pawlowsky.]
+
+Following Graber, it is generally stated that the mouth-parts consist of
+a short tube furnished with hooks in front, which constitutes the lower
+lip, and that within this is a delicate sucking tube derived from the
+fusion of the labrum and the mandibles. Opposed to this, Cholodkovsky
+and, more recently, Pawlowsky, (1906), have shown that the piercing
+apparatus lies in a blind sac under the pharynx and opening into the
+mouth cavity (fig. 64). It does not form a true tube but a furrow with
+its open surface uppermost. Eysell has shown that, in addition, there is
+a pair of chitinous rods which he regards as the homologues of the
+maxillæ.
+
+When the louse feeds, it everts the anterior part of the mouth cavity,
+with its circle of hooks. The latter serve for anchoring the bug, and
+the piercing apparatus is then pushed out.
+
+[Illustration: 65. Pediculus humanus, ventral aspect of male. (×10)]
+
+Most writers have classed the sucking lice as a sub-order of the
+Hemiptera, but the more recent anatomical and developmental studies
+render this grouping untenable. An important fact, bearing on the
+question, is that, as shown by Gross, (1905), the structure of the
+ovaries is radically different from that of the Hemiptera.
+
+Lice infestation and its effects are known medically as _pediculosis_.
+Though their continued presence is the result of the grossest neglect
+and filthiness, the original infestation may be innocently obtained and
+by people of the most careful habits.
+
+Three species commonly attack man. Strangely enough, there are very few
+accurate data regarding their life history.
+
+_Pediculus humanus_ (fig. 65), the head louse, is the most widely
+distributed. It is usually referred to in medical literature as
+_Pediculus capitis_, but the Linnean specific name has priority. In
+color it is of a pale gray, blackish on the margins. It is claimed by
+some authors that the color varies according to the color of the skin of
+the host. The abdomen is composed of seven distinct segments, bearing
+spiracles laterally. There is considerable variation in size. The males
+average 1.8 mm. and the females 2.7 mm. in length.
+
+The eggs, fifty to sixty in number, stick firmly to the hairs of the
+host and are known as nits. They are large and conspicuous, especially
+on dark hair and are provided with an operculum, or cap, at the free
+end, where the nymphs emerge. They hatch in about six days and about the
+eighteenth day the young lice are sexually mature.
+
+[Illustration: 66. Pediculosis of the head. The illustration shows the
+characteristic indications of the presence of lice, viz: the occipital
+eczema gluing the hairs together, the swollen cervical glands, and the
+porrigo, or eruption of contagious pustules upon the neck. After Fox.]
+
+The head lice live by preference on the scalp of their host but
+occasionally they are found on the eyelashes and beard, or in the pubic
+region. They may also occur elsewhere on the body. The penetration of
+the rostrum into the skin and the discharge of an irritating saliva
+produce a severe itching, accompanied by the formation of an eczema-like
+eruption (fig. 66). When the infestation is severe, the discharge from
+the pustules mats down the hair, and scabs are formed, under which the
+insects swarm. "If allowed to run, a regular carapace may form, called
+_trichoma_, and the head exudes a foetid odor. Various low plants may
+grow in the trichoma, the whole being known as _plica
+palonica_."--Stiles.
+
+Sources of infestation are various. School children may obtain the lice
+from seatmates, by wearing the hats or caps of infested mates, or by the
+use, in common, of brushes and combs. They may be obtained from infested
+beds or sleeper berths. Stiles reports an instance in which a large
+number of girls in a fashionable boarding school developed lousiness a
+short time after traveling in a sleeping car.
+
+Treatment is simple, for the parasites may readily be controlled by
+cleanliness and washing the head with a two per cent solution of
+carbolic acid or even kerosene. The latter is better used mixed with
+equal parts of olive oil, to avoid irritation. The treatment should be
+applied at night and followed the next morning by a shampoo with soap
+and warm water. It is necessary to repeat the operation in a few days.
+Xylol, used pure, or with the addition of five per cent of vaseline, is
+also very efficacious. Of course, the patient must be cautioned to stay
+away from a lighted lamp or fire while using either the kerosene or
+xylol. While these treatments will kill the eggs or nits, they will not
+remove them from the hairs. Pusey recommends repeated washings with
+vinegar or 25 per cent of acetic acid in water, for the purpose of
+loosening and removing the nits.
+
+Treatment of severe infestations in females is often troublesome on
+account of long hair. For such cases the following method recommended by
+Whitfield (1912) is especially applicable:
+
+The patient is laid on her back on the bed with her head over the edge,
+and beneath the head is placed a basin on a chair so that the hair lies
+in the basin. A solution of 1 in 40 carbolic acid is then poured over
+the hair into the basin and sluiced backwards and forwards until the
+whole of the hair is thoroughly soaked with it. It is especially
+necessary that care should be taken to secure thorough saturation of the
+hair over the ears and at the nape of the neck, since these parts are
+not only the sites of predilection of the parasites but they are apt to
+escape the solution. This sluicing is carried out for ten minutes by the
+clock. At the end of ten minutes the hair is lifted from the basin and
+allowed to drain, but is not dried or even thoroughly wrung out. The
+whole head is then swathed with a thick towel or better, a large piece
+of common house flannel, which is fastened up to form a sort of turban,
+and is allowed to remain thus for an hour. It can then be washed or
+simply allowed to dry, as the carbolic quickly disperses. At the end of
+this period every pediculus and what is better, every ovum is dead and
+no relapse will occur unless there is exposure to fresh contagion.
+Whitfield states that there seem to be no disadvantages in this method,
+which he has used for years. He has never seen carboluria result from
+it, but would advise first cutting the hair of children under five years
+of age.
+
+_Pediculus corporis_ (= _P. vestimenti_) the body louse, is larger than
+the preceding species, the female measuring 3.3 mm., and the male 3 mm.
+in length. The color is a dirty white, or grayish. _P. corporis_ has
+been regarded by some authorities as merely a variety of _P. humanus_
+but Piaget maintains there are good characters separating the two
+species.
+
+The body louse lives in the folds and seams of the clothing of its host,
+passing to the skin only when it wishes to feed. Brumpt states that he
+has found enormous numbers of them in the collars of glass-ware or
+grains worn by certain naked tribes in Africa.
+
+Exact data regarding the life-history of this species have been
+supplied, in part, by the work of Warburton (1910), cited by Nuttall. He
+found that _Pediculus corporis_ lives longer than _P. humanus_ under
+adverse conditions. This is doubtless due to its living habitually on
+the clothing, whereas _humanus_ lives upon the head, where it has more
+frequent opportunities of feeding. He reared a single female upon his
+own person, keeping the louse enclosed in a cotton-plugged tube with a
+particle of cloth to which it could cling. The tube was kept next to his
+body, thus simulating the natural conditions of warmth and moisture
+under which the lice thrive. The specimen was fed twice daily, while it
+clung to the cloth upon which it rested. Under these conditions she
+lived for one month. Copulation commenced five days after the female had
+hatched and was repeated a number of times, sexual union lasting for
+hours. The female laid one hundred and twenty-four eggs within
+twenty-five days.
+
+The eggs hatched after eight days, under favorable conditions, such as
+those under which the female was kept. They did not hatch in the cold.
+Eggs kept near the person during the day and hung in clothing by the
+bedside at night, during the winter, in a cold room, did not hatch until
+the thirty-fifth day. When the nymphs emerge from the eggs, they feed at
+once, if given a chance to do so. They are prone to scatter about the
+person and abandon the fragment of cloth to which the adult clings.
+
+The adult stage is reached on the eleventh day, after three molts, about
+four days apart. Adults enter into copulation about the fifth day and as
+the eggs require eight days for development, the total cycle, under
+favorable conditions, is about twenty-four days. Warburton's data differ
+considerably from those commonly quoted and serve to emphasize the
+necessity for detailed studies of some of the commonest of parasitic
+insects.
+
+Body lice are voracious feeders, producing by their bites and the
+irritating saliva which they inject, rosy elevations and papules which
+become covered with a brownish crust. The intense itching provokes
+scratching, and characteristic white scars (fig. 67) surrounded by
+brownish pigment (fig. 68) are formed. The skin may become thickened and
+take on a bronze tinge. This melanoderma is especially marked in the
+region between the shoulders but it may become generalized, a prominent
+characteristic of "vagabond's disease." According to Dubre and Beille,
+this melanoderma is due to a toxic substance secreted by the lice, which
+indirectly provokes the formation of pigment.
+
+[Illustration: 67. Pediculosis in man caused by the body louse. After
+Morrow.]
+
+Control measures, in the case of the body louse, consist in boiling or
+steaming the clothes or in some cases, sterilizing by dry heat. The
+dermatitis may be relieved by the use of zinc-oxide ointment, to which
+Pusey recommends that there be added, on account of their parasiticidal
+properties, sulphur and balsam of Peru, equal parts, 15 to 30 grains to
+the ounce.
+
+_Phthirius pubis_ (= _P. inguinalis_), the pubic louse, or so-called
+"crab louse," differs greatly from the preceding in appearance. It is
+characterized by its relatively short head which fits into a broad
+depression in the thorax. The latter is broad and flat and merges into
+the abdomen. The first pair of legs is slender and terminated by a
+straight claw. The second and third pairs of legs are thicker and are
+provided with powerful claws fitted for clinging to hairs. The females
+(fig. 69) measure 1.5 to 2 mm. in length by 1.5 mm. in breadth. The male
+averages a little over half as large. The eggs, or nits, are fixed at
+the base of the hairs. Only a few, ten to fifteen are deposited by a
+single female, and they hatch in about a week's time. The young lice
+mature in two weeks.
+
+The pubic louse usually infests the hairs of the pubis and the perineal
+region. It may pass to the arm pits or even to the beard or moustache.
+Rarely, it occurs on the eyelids, and it has even been found, in a very
+few instances, occurring in all stages, on the scalp. Infestation may be
+contracted from beds or even from badly infested persons in a crowd. We
+have seen several cases which undoubtedly were due to the use of public
+water closets. It produces papular eruption and an intense pruritis.
+When abundant, there occurs a grayish discoloration of the skin which
+Duguet has shown is due to a poisonous saliva injected by the louse, as
+is the melanoderma caused by the body louse.
+
+[Illustration: 68. Melanoderma caused by the body louse. From Portfolio
+of Dermochromes, by permission of Rebman & Co., New York, Publishers.]
+
+The pubic louse may be exterminated by the measures recommended for the
+head louse, or by the use of officinal mercurial ointment.
+
+[Illustration: 69. Phthirius pubis. Ventral aspect of female. (×12).]
+
+
+HEMIPTERA
+
+Several species of HEMIPTERA-HETEROPTERA are habitual parasites of man,
+and others occur as occasional or accidental parasites. Of all these,
+the most important and widespread are the bed-bugs, belonging to the
+genus _Cimex_ (= _Acanthia_).
+
+
+THE BED-BUGS--The bed-bugs are characterized by a much flattened oval
+body, with the short, broad head unconstricted behind, and fitting into
+the strongly excavated anterior margin of the thorax. The compound eyes
+are prominent, simple eyes lacking. Antennæ four-jointed, the first
+segment short, the second long and thick, and the third and fourth
+slender. The tarsi are short and three segmented.
+
+It is often assumed in the literature of the subject that there is but a
+single species of _Cimex_ attacking man, but several such species are to
+be recognized. These are distinguishable by the characters given in
+Chapter XII. We shall consider especially _Cimex lectularius_, the most
+common and widespread species.
+
+_Cimex lectularius_ (= _Acanthia lectularia_, _Clinocoris
+lectularius_), is one of the most cosmopolitan of human parasites but,
+like the lice, it has been comparatively little studied until recent
+years, when the possibility that it may be concerned with the
+transmission of various diseases has awakened interest in the details of
+its life-history and habits.
+
+[Illustration: 70. Cimex lectularius adult and eggs. Photograph by M. V.
+S.]
+
+The adult insect (fig. 70) is 4-5 mm. long by 3 mm. broad, reddish brown
+in color, with the beak and body appendages lighter in color. The short,
+broad and somewhat rectangular head has no neck-like constriction but
+fits into the broadly semilunar prothorax. The four segmented labium or
+proboscis encloses the lancet-like maxillæ and mandibles. The distal of
+the four antennal segments is slightly club-shaped. The prothorax is
+characteristic of the species, being deeply incised anteriorly and with
+its thin lateral margins somewhat turned up. The mesothorax is
+triangular, with the apex posteriorly, and bears the greatly atrophied
+first pair of wings. There is no trace of the metathoracic pair. The
+greatly flattened abdomen has eight visible segments, though in reality
+the first is greatly reduced and has been disregarded by most writers.
+The body is densely covered with short bristles and hairs, the former
+being peculiarly saber-shaped structures sharply toothed at the apex and
+along the convex side (fig. 159_b_).
+
+The peculiar disagreeable odor of the adult bed-bug is due to the
+secretion of the stink glands which lie on the inner surface of the
+mesosternum and open by a pair of orifices in front of the metacoxæ,
+near the middle line. In the nymphs, the thoracic glands are not
+developed but in the abdomen there are to be found three unpaired dorsal
+stink glands, which persist until the fifth molt, when they become
+atrophied and replaced by the thoracic glands. The nymphal glands occupy
+the median dorsal portion of the abdomen, opening by paired pores at the
+anterior margin of the fourth, fifth and sixth segments. The secretion
+is a clear, oily, volatile fluid, strongly acid in reaction. Similar
+glands are to be found in most of the Hemiptera-Heteroptera and their
+secretion is doubtless protective, through being disagreeable to the
+birds. In the bed-bug, as Marlatt points out, "it is probably an
+illustration of a very common phenomenon among animals, i.e., the
+persistence of a characteristic which is no longer of any special value
+to the possessor." In fact, its possession is a distinct disadvantage to
+the bed-bug, as the odor frequently reveals the presence of the bugs,
+before they are seen.
+
+The eggs of the bed-bug (fig. 70) are pearly white, oval in outline,
+about a millimeter long, and possess a small operculum or cap at one
+end, which is pushed off when the young hatches. They are laid
+intermittently, for a long period, in cracks and crevices of beds and
+furniture, under seams of mattresses, under loose wall paper, and
+similar places of concealment of the adult bugs. Girault (1905) observed
+a well-fed female deposit one hundred and eleven eggs during the
+sixty-one days that she was kept in captivity. She had apparently
+deposited some of her eggs before being captured.
+
+The eggs hatch in six to ten days, the newly emerged nymphs being about
+1.5 mm. in length and of a pale yellowish white color. They grow slowly,
+molting five times. At the last molt the mesathoracic wing pads appear,
+characteristic of the adult. The total length of the nymphal stage
+varies greatly, depending upon conditions of food supply, temperature
+and possibly other factors. Marlatt (1907) found under most favorable
+conditions a period averaging eight days between molting which, added to
+an equal egg period, gave a total of about seven weeks from egg to adult
+insect. Girault (1912) found the postembryonic period as low as
+twenty-nine days and as high as seventy days under apparently similar
+and normal conditions of food supply. Under optimum and normal
+conditions of food supply, beginning August 27, the average nymphal life
+was 69.9 days; average number of meals 8.75 and the molts 5. Under
+conditions allowing about half the normal food supply the average
+nymphal life was from 116.9 to 139 days. Nymphs starved from birth lived
+up to 42 days. We have kept unfed nymphs, of the first stage, alive in a
+bottle for 75 days. The interesting fact was brought out that under
+these conditions of minimum food supply there were sometimes six molts
+instead of the normal number.
+
+The adults are remarkable for their longevity, a factor which is of
+importance in considering the spread of the insect and methods of
+control. Dufour (1833) (not De Geer, as often stated) kept specimens for
+a year, in a closed vial, without food. This ability, coupled with their
+willingness to feed upon mice, bats, and other small mammals, and even
+upon birds, accounts for the long periods that deserted houses and camps
+may remain infested. There is no evidence that under such conditions
+they are able to subsist on the starch of the wall paper, juices of
+moistened wood, or the moisture in the accumulations of dust, as is
+often stated.
+
+There are three or four generations a year, as Girault's breeding
+experiments have conclusively shown. He found that the bed-bug does not
+hibernate where the conditions are such as to allow it to breed and that
+breeding is continuous unless interrupted by the lack of food or, during
+the winter, by low temperature.
+
+Bed-bugs ordinarily crawl from their hiding places and attack the face
+and neck or uncovered parts of the legs and arms of their victims. If
+undisturbed, they will feed to repletion. We have found that the young
+nymph would glut itself in about six minutes, though some individuals
+fed continuously for nine minutes, while the adult required ten to
+fifteen minutes for a full meal. When gorged, it quickly retreats to a
+crack or crevice to digest its meal, a process which requires two or
+three days. The effect of the bite depends very greatly on the
+susceptibility of the individual attacked. Some persons are so little
+affected that they may be wholly ignorant of the presence of a large
+number of bugs. Usually the bite produces a small hard swelling, or
+wheal, whitish in color. It may even be accompanied by an edema and a
+disagreeable inflammation, and in such susceptible individuals the
+restlessness and loss of sleep due to the presence of the insects may be
+a matter of considerable importance. Stiles (1907) records the case of a
+young man who underwent treatment for neurasthenia, the diagnosis being
+agreed upon by several prominent physicians; all symptoms promptly
+disappeared, however, immediately following a thorough fumigation of
+his rooms, where nearly a pint of bed-bugs were collected.
+
+It is natural to suppose that an insect which throughout its whole life
+is in such intimate relationship with man should play an important rôle
+in the transmission of disease. Yet comparatively little is definitely
+known regarding the importance of the bed-bug in this respect. It has
+been shown that it is capable of transmitting the bubonic plague, and
+South American trypanosomiasis. Nuttall succeeded in transmitting
+European relapsing fever from mouse to mouse by its bite. It has been
+claimed that Oriental sore, tuberculosis, and even syphilis may be so
+carried. These phases of the subject will be considered later.
+
+The sources of infestation are many, and the invasion of a house is not
+necessarily due to neglect, though the continued presence of the pests
+is quite another matter. In apartments and closely placed houses they
+are known to invade new quarters by migration. They are frequently to be
+met with in boat and sleeper berths, and even the plush seats of day
+coaches, whence a nucleus may be carried in baggage to residences. They
+may be brought in the laundry or in clothes of servants.
+
+Usually they are a great scourge in frontier settlements and it is
+generally believed that they live in nature under the bark of trees, in
+lumber, and under similar conditions. This belief is founded upon the
+common occurrence of bugs resembling the bed-bug, in such places. As a
+matter of fact, they are no relation to bed-bugs but belong to
+plant-feeding forms alone (fig. 19 _c_, _d_).
+
+It is also often stated that bed-bugs live in poultry houses, in
+swallows nests, and on bats, and that it is from these sources that they
+gain access to dwellings. These bugs are specifically distinct from the
+true bed-bug, but any of them may, rarely, invade houses. Moreover,
+chicken houses are sometimes thoroughly infested with the true _Cimex
+lectularius_.
+
+Control measures consist in the use of iron bedsteads and the reduction
+of hiding places for the bugs. If the infestation is slight they may be
+exterminated by a vigilant and systematic hunt, and by squirting
+gasoline or alcohol into cracks and crevices of the beds, and furniture.
+Fumigation must be resorted to in more general infestations.
+
+The simplest and safest method of fumigation is by the use of flowers of
+sulphur at the rate of two pounds to each one thousand cubic feet of
+room space. The sulphur should be placed in a pan, a well made in the
+top of the pile and a little alcohol poured in, to facilitate burning.
+The whole should be placed in a larger pan and surrounded by water so as
+to avoid all danger of fire. Windows should be tightly closed, beds,
+closets and drawers opened, and bedding spread out over chairs in order
+to expose them fully to the fumes. As metal is tarnished by the sulphur
+fumes, ornaments, clocks, instruments, and the like should be removed.
+When all is ready the sulphur should be fired, the room tightly closed
+and left for twelve to twenty-four hours. Still more efficient in large
+houses, or where many hiding places favor the bugs, is fumigation with
+hydrocyanic acid gas. This is a deadly poison and must be used under
+rigid precautions. Through the courtesy of Professor Herrick, who has
+had much experience with this method, we give in the Appendix, the clear
+and detailed directions taken from his bulletin on "Household Insects."
+
+Fumigation with formaldehyde gas, either from the liquid or "solid"
+formalin, so efficient in the case of contagious diseases, is useless
+against bed-bugs and most other insects.
+
+
+OTHER BED-BUGS--_Cimex hemipterus_ (= _C. rotundatus_) is a tropical and
+subtropical species, occurring in both the old and new world. Patton and
+Cragg state that it is distributed throughout India, Burma, Assam, the
+Malay Peninsula, Aden, the Island of Mauritius, Reunion, St. Vincent and
+Porto Rico. "It is widely distributed in Africa, and is probably the
+common species associated there with man." Brumpt also records it for
+Cuba, the Antilles, Brazil, and Venezuela.
+
+This species, which is sometimes called the Indian bed-bug, differs from
+_C. lectularius_ in being darker and in having a more elongate abdomen.
+The head also is shorter and narrower, and the prothorax has rounded
+borders.
+
+It has the same habits and practically the same life cycle as _Cimex
+lectularius_. Mackie, in India, has found that it is capable of
+transmitting the Asiatic type of recurrent fever. Roger suggested that
+it was also capable of transmitting Kala-azar and Patton has described
+in detail the developmental stages of _Leishmania_, the causative
+organism of Kala-azar, in the stomach of this bug, but Brumpt declares
+that the forms described are those of a common, non-pathogenic
+flagellate to be found in the bug, and have nothing to do with the
+human disease. Brumpt has shown experimentally that _Cimex hemipterus_
+may transmit _Trypanosoma cruzi_ in its excrement.
+
+_Cimex boueti_, occurring in French Guinea, is another species attacking
+man. Its habits and general life history are the same as for the above
+species. It is 3 to 4.5 mm. in length, has vestigial elytra, and much
+elongated antennæ and legs. The extended hind legs are about as long as
+the body.
+
+_Cimex columbarius_, a widely distributed species normally living in
+poultry houses and dove cotes, _C. inodorus_, infesting poultry in
+Mexico, _C. hirundinis_, occurring in the nests of swallows in Europe
+and _Oeciacus vicarius_ (fig. 19i) occurring in swallows' nests in this
+country, are species which occasionally infest houses and attack man.
+
+[Illustration: 71. Conorhinus sanguisugus.]
+
+_Conorhinus sanguisugus_, the cone-nosed bed-bug. We have seen in our
+consideration of poisonous insects, that various species of Reduviid
+bugs readily attack man. Certain of these are nocturnal and are so
+commonly found in houses that they have gained the name, of "big
+bed-bugs." The most noted of these, in the United States, is _Conorhinus
+sanguisugus_ (fig. 71), which is widely distributed in our Southern
+States.
+
+Like its near relatives, _Conorhinus sanguisugus_ is carnivorous in
+habit and feeds upon insects as well as upon mammalian and human blood.
+It is reported as often occurring in poultry houses and as attacking
+horses in barns. The life history has been worked out in considerable
+detail by Marlatt, (1902), from whose account we extract the following.
+
+[Illustration: 72. Beak of Conorhinus sanguisugus. After Marlatt.]
+
+The eggs are white, changing to yellow and pink before hatching. The
+young hatch within twenty days and there are four nymphal stages. In all
+these stages the insect is active and predaceous, the mouth-parts (fig.
+72) being powerfully developed. The eggs are normally deposited, and the
+early stages are undoubtedly passed, out of doors, the food of the
+immature forms being other insects. Immature specimens are rarely found
+indoors. It winters both in the partly grown and adult stage, often
+under the bark of trees or in any similar protection, and only in its
+nocturnal spring and early summer flights does it attack men. Marlatt
+states that this insect seems to be decidedly on the increase in the
+region which it particularly infests,--the plains region from Texas
+northward and westward. In California a closely related species of
+similar habits is known locally as the "monitor bug."
+
+The effect of the bite of the giant bed-bug on man is often very severe,
+a poisonous saliva apparently being injected into the wound. We have
+discussed this phase of the subject more fully under the head of
+poisonous insects.
+
+_Conorhinus megistus_ is a Brazilian species very commonly attacking
+man, and of special interest since Chagas has shown that it is the
+carrier of a trypanosomiasis of man. Its habits and life history have
+been studied in detail by Neiva, (1910).
+
+This species is now pre-eminently a household insect, depositing its
+eggs in cracks and crevices in houses, though this is a relatively
+recent adaptation. The nymphs emerge in from twenty to forty days,
+depending upon the temperature. There are five nymphal stages, and as in
+the case of true bed-bugs, the duration of these is very greatly
+influenced by the availability of food and by temperature. Neiva reckons
+the entire life cycle, from egg to egg, as requiring a minimum of three
+hundred and twenty-four days.
+
+The nymphs begin to suck blood in three to five days after hatching.
+They usually feed at night and in the dark, attacking especially the
+face of sleeping individuals. The bite occasions but little pain. The
+immature insects live in cracks and crevices in houses and invade the
+beds which are in contact with walls, but the adults are active flyers
+and attack people sleeping in hammocks. The males as well as the females
+are blood suckers.
+
+Like many blood-sucking forms, _Conorhinus megistus_ can endure for long
+periods without food. Neiva received a female specimen which had been
+for fifty-seven days alive in a tightly closed box. They rarely feed on
+two consecutive days, even on small quantities of blood, and were never
+seen to feed on three consecutive days.
+
+Methods of control consist in screening against the adult bugs, and the
+elimination of crevices and such hiding places of the nymphs. Where the
+infestation is considerable, fumigation with sulphur is advisable.
+
+
+PARASITIC DIPTERA OR FLIES
+
+Of the DIPTERA or two-winged flies, many species occasionally attack
+man. Of these, a few are outstanding pests, many of them may also serve
+to disseminate disease, a phase of our subject which will be considered
+later. We shall now consider the most important of the group from the
+viewpoint of their direct attacks on man.
+
+
+Psychodidæ or Moth-Flies
+
+The PSYCHODIDÆ or Moth-flies, include a few species which attack man,
+and at least one species, _Phlebotomus papatasii_, is known to transmit
+the so-called "three-day fever" of man. Another species is supposed to
+be the vector of Peruvian verruga.
+
+The family is made up of small, sometimes very small, nematocerous
+Diptera, which are densely covered with hairs, giving them a moth-like
+appearance. The wings are relatively large, oval or lanceolate in shape,
+and when at rest are held in a sloping manner over the abdomen, or are
+held horizontally in such a way as to give the insect a triangular
+outline. Not only is the moth-like appearance characteristic, but the
+venation of the wings (fig. 163, d) is very peculiar and, according to
+Comstock, presents an extremely generalized form. All of the
+longitudinal veins separate near the base of the wing except veins R_2
+and R_3 and veins M_1 and M_2. Cross veins are wanting in most cases.
+
+Comparatively little is known regarding the life-history and habits of
+the Psychodidæ, but one genus, _Phlebotomus_, contains minute,
+blood-sucking species, commonly known as sand-flies. The family is
+divided into two subfamilies, the PSYCHODINÆ and the PHLEBOTOMINÆ. The
+second of these, the PHLEBOTOMINÆ, is of interest to us.
+
+
+THE PHLEBOTOMINÆ--The Phlebotominæ differ from the Psychodinæ in that
+the radical sector branches well out into the wing rather than at the
+base of the wing. They are usually less hairy than the Psychodinæ. The
+ovipositor is hidden and less strongly chitinized. The species attacking
+man belong to the genus _Phlebotomus_, small forms with relatively
+large, hairy wings which are held upright, and with elongate proboscis.
+The mandibles and maxillæ are serrated and fitted for biting.
+
+According to Miss Summers (1913) there are twenty-nine known species of
+the genus _Phlebotomus_, five European, eleven Asiatic, seven African
+and six American. One species only, _Phlebotomus vexator_, has been
+reported for the United States. This was described by Coquillett,
+(1907), from species taken on Plummer's Island, Maryland. It measures
+only 1.5 mm. in length. As it is very probable that this species is much
+more widely distributed, and that other species of these minute flies
+will be found to occur in our fauna, we quote Coquillett's description.
+
+_Phlebotomus vexator_, Coq.: Yellow, the mesonotum brown, hairs chiefly
+brown; legs in certain lights appear brown, but are covered with a white
+tomentum; wings hyaline, unmarked; the first vein (R_1) terminates
+opposite one-fifth of the length of the first submarginal cell (cell
+R_2); this cell is slightly over twice as long as its petiole; terminal,
+horny portion of male claspers slender, bearing many long hairs; the
+apex terminated by two curved spines which are more than one-half as
+long as the preceding part, and just in front of these are two similar
+spines, while near the middle of the length of this portion is a fifth
+spine similar to the others. Length 1.5 mm.
+
+The life-history of the Phlebotomus flies has been best worked out for
+the European _Phlebotomus papatasii_ and we shall briefly summarize the
+account of Doerr and Russ (1913) based primarily on work on this
+species. The European Phlebotomus flies appear at the beginning of the
+warm season, a few weeks after the cessation of the heavy rains and
+storms of springtime. They gradually become more abundant until they
+reach their first maximum, which in Italy is near the end of July
+(Grassi). They then become scarcer but reach a second maximum in
+September. At the beginning of winter they vanish completely,
+hibernating individuals not being found.
+
+After fertilization there is a period of eight to ten days before
+oviposition. The eggs are then deposited, the majority in a single mass
+covered by a slimy secretion from the sebaceous glands. The larvæ emerge
+in fourteen to twenty days. There is uncertainty as to the length of
+larval life, specimens kept in captivity remaining fifty or more days
+without transforming. Growth may be much more rapid in nature. The larvæ
+do not live in fluid media but in moist detritus in dark places. Marett
+believes that they live chiefly on the excrement of pill-bugs (Oniscidæ)
+and lizards. Pupation always occurs during the night. The remnants of
+the larval skin remain attached to the last two segments of the
+quiescent pupa and serve to attach it to the stone on which it lives.
+The pupal stage lasts eleven to sixteen days, the adult escaping at
+night.
+
+Only the females suck blood. They attack not only man but all
+warm-blooded animals and, according to recent workers, also cold-blooded
+forms, such as frogs, lizards, and larvæ. Indeed, Townsend (1914)
+believes that there is an intimate relation between _Phlebotomus_ and
+lizards, or other reptiles the world over. The Phlebotomus passes the
+daylight hours within the darkened recesses of the loose stone walls and
+piles of rock in order to escape wind and strong light. Lizards inhabit
+the same places, and the flies, always ready to suck blood in the
+absence of light and wind, have been found more prone to suck reptilian
+than mammalian blood.
+
+On hot summer nights, when the wind is not stirring, the Phlebotomus
+flies, or sand-flies, as they are popularly called, invade houses and
+sleeping rooms in swarms and attack the inmates. As soon as light begins
+to break the flies either escape to the breeding places, or cool, dark
+places protected from the wind, or a part of them remain in the rooms,
+hiding behind pictures, under garments, and in similar places. Wherever
+the Phlebotomus flies occur they are an intolerable nuisance. On account
+of their small size they can easily pass through the meshes of ordinary
+screens and mosquito curtains. They attack silently and inflict a very
+painful, stinging bite, followed by itching. The ankles, dorsum of the
+feet, wrists, inner elbow, knee joint and similar places are favorite
+places of attack, possibly on account of their more delicate skin.
+
+Special interest has been attracted to these little pests in recent
+years, since it has been shown that they transmit the European
+"pappatici fever" or "three day fever." More recently yet, it appears
+that they are the carriers of the virus of the Peruvian "verruga." This
+phase of the subject will be discussed later.
+
+Control measures have not been worked out. As Newstead says, "In
+consideration of the facts which have so far been brought to light
+regarding the economy of Phlebotomus, it is clearly evident that the
+task of suppressing these insects is an almost insurmountable one. Had
+we to deal with insects as large and as accessible as mosquitoes, the
+adoption of prophylactic measures would be comparatively easy, but owing
+to the extremely minute size and almost flea-like habits of the adult
+insects, and the enormous area over which the breeding-places may occur,
+we are faced with a problem which is most difficult of solution." For
+these reasons, Newstead considers that the only really prophylactic
+measures which can at present be taken, are those which are considered
+as precautionary against the bites of the insects.
+
+Of repellents, he cites as one of the best a salve composed of the
+following:
+
+  Ol. Anisi                                                    3 grs.
+  Ol. Eucalypti                                                3 grs.
+  Ol. Terebenth                                                3 grs.
+  Unq. Acid Borac.
+
+Of sprays he recommends as the least objectionable and at the same time
+one of the most effective, formalin. "The dark portions and angles of
+sleeping apartments should be sprayed with a one per cent. solution of
+this substance every day during the season in which the flies are
+prevalent. A fine spraying apparatus is necessary for its application
+and an excessive amount must not be applied. It is considered an
+excellent plan also to spray the mosquito curtains regularly every day
+towards sunset; nets thus treated are claimed to repel the attacks of
+these insects." This effectiveness of formalin is very surprising for,
+as we have seen, it is almost wholly ineffective against bed-bugs,
+mosquitoes, house flies and other insects, where it has been tried.
+
+A measure which promises to be very effective, where it can be adopted,
+is the use of electric fans so placed as to produce a current of air in
+the direction of the windows of sleeping apartments. On account of the
+inability of the Phlebotomus flies to withstand even slight breezes, it
+seems very probable that they would be unable to enter a room so
+protected.
+
+
+Culicidæ or Mosquitoes
+
+From the medical viewpoint, probably the most interesting and important
+of the blood-sucking insects are the mosquitoes. Certainly this is true
+of temperate zones, such as those of the United States. The result is
+that no other group of insects has aroused such widespread interest, or
+has been subjected to more detailed study than have the mosquitoes,
+since their rôle as carriers of disease was made known. There is an
+enormous literature dealing with the group, but fortunately for the
+general student, this has been well summarized by a number of workers.
+The most important and helpful of the general works are those of Howard
+(1901), Smith (1904), Blanchard (1905), Mitchell (1907), and especially
+of Howard, Dyar, and Knab, whose magnificent monograph is still in
+course of publication.
+
+Aside from their importance as carriers of disease, mosquitoes are
+notorious as pests of man, and the earlier literature on the group is
+largely devoted to references to their enormous numbers and their
+blood-thirstiness in certain regions. They are to be found in all parts
+of the world, from the equator to the Arctic and Antarctic regions.
+Linnæus, in the "Flora Lapponica," according to Howard, Dyar and Knab,
+"dwells at some length upon the great abundance of mosquitoes in Lapland
+and the torments they inflicted upon man and beast. He states that he
+believes that nowhere else on earth are they found in such abundance and
+he compares their numbers to the dust of the earth. Even in the open,
+you cannot draw your breath without having your mouth and nostrils
+filled with them; and ointments of tar and cream or of fish grease are
+scarcely sufficient to protect even the case-hardened cuticle of the
+Laplander from their bite. Even in their cabins, the natives cannot take
+a mouthful of food or lie down to sleep unless they are fumigated almost
+to suffocation." In some parts of the Northwestern and Southwestern
+United States it is necessary to protect horses working in the fields by
+the use of sheets or burlaps, against the ferocious attacks of these
+insects. It is a surprising fact that even in the dry deserts of the
+western United States they sometimes occur in enormous numbers.
+
+Until comparatively recent years, but few species of mosquitoes were
+known and most of the statements regarding their life-history were based
+upon the classic work of Reaumur (1738) on the biology of the rain
+barrel mosquito, _Culex pipiens_. In 1896, Dr. Howard refers to
+twenty-one species in the United States, now over fifty are known;
+Giles, in 1900, gives a total of two hundred and forty-two for the world
+fauna, now over seven hundred species are known. We have found eighteen
+species at Ithaca, N. Y.
+
+All of the known species of mosquitoes are aquatic in the larval stage,
+but in their life-histories and habits such great differences occur that
+we now know that it is not possible to select any one species as typical
+of the group. For our present purpose we shall first discuss the general
+characteristics and structure of mosquitoes, and shall then give the
+life-history of a common species, following this by a brief
+consideration of some of the more striking departures from what have
+been supposed to be the typical condition.
+
+The CULICIDÆ are slender, nematocerous Diptera with narrow wings,
+antennæ plumose in the males, and usually with the proboscis much longer
+than the head, slender, firm and adapted for piercing in the female.
+The most characteristic feature is that the margins of the wings and, in
+most cases, the wing veins possess a fringe of scale-like hairs. These
+may also cover in part, or entirely, the head, thorax, abdomen and legs.
+The females, only, suck blood.
+
+On account of the importance of the group in this country and the
+desirability of the student being able to determine material in various
+stages, we show in the accompanying figures the characters most used in
+classification.
+
+The larvæ (fig. 73) are elongate, with the head and thorax sharply
+distinct. The larval antennæ are prominent, consisting of a single
+cylindrical and sometimes curved segment. The outer third is often
+narrower and bears at its base a fan-shaped tuft of hairs, the
+arrangement and abundance of which is of systematic importance. About
+the mouth are the so-called rotary mouth brushes, dense masses of long
+hairs borne by the labrum and having the function of sweeping food into
+the mouth. The form and arrangement of thoracic, abdominal, and anal
+tufts of hair vary in different species and present characteristics of
+value. On either side of the eighth abdominal segment is a patch of
+scales varying greatly in arrangement and number and of much value in
+separating species. Respiration is by means of tracheæ which open at the
+apex of the so-called anal siphon, when it is present. In addition,
+there are also one or two pairs of tracheal gills which vary much in
+appearance in different species. On the ventral side of the anal siphon
+is a double row of flattened, toothed spines whose number and shape are
+likewise of some value in separating species. They constitute the comb
+or pecten.
+
+[Illustration: 73. Culex larva showing details of external structure.]
+
+The pupa (fig. 139, b) unlike that of most insects, is active, though it
+takes no food. The head and thorax are not distinctly separated, but the
+slender flexible abdomen in sharply marked off. The antennæ,
+mouth-parts, legs, and wings of the future adult are now external, but
+enclosed in chitinous cases. On the upper surface, near the base of the
+wings are two trumpets, or breathing tubes, for the pupal spiracles are
+towards the anterior end instead of at the caudal end, as in the larva.
+At the tip of the abdomen is a pair of large chitinous swimming paddles.
+
+As illustrative of the life cycle of a mosquito we shall discuss the
+development of a common house mosquito, _Culex pipiens_, often referred
+to in the Northern United States as the rain barrel mosquito. Its life
+cycle is often given as typical for the entire group, but, as we have
+already emphasized, no one species can serve this purpose.
+
+The adults of _Culex pipiens_ hibernate throughout the winter in
+cellars, buildings, hollow trees, or similar dark shelters. Early in the
+spring they emerge and deposit their eggs in a raft-like mass. The
+number of eggs in a single mass is in the neighborhood of two hundred,
+recorded counts varying considerably. A single female may deposit
+several masses during her life time. The duration of the egg stage is
+dependent upon temperature. In the warm summer time the larvæ may emerge
+within a day. The larvæ undergo four molts and under optimum conditions
+may transform into pupæ in about a week's time. Under the same favorable
+conditions, the pupal stage may be completed in a day's time. The total
+life cycle of _Culex pipiens_, under optimum conditions, may thus be
+completed in a week to ten days. This period may be considerably
+extended under less favorable conditions of temperature and food supply.
+
+_Culex pipiens_ breeds continuously throughout the summer, developing in
+rain barrels, horse troughs, tin cans, or indeed in any standing water
+about houses, which lasts for a week or more. The catch basins of sewers
+furnish an abundant supply of the pests under some conditions. Such
+places, the tin gutters on residences, and all possible breeding places
+must be considered in attempts to exterminate this species.
+
+Other species of mosquitoes may exhibit radical departures from _Culex
+pipiens_ in life-history and habits. To control them it is essential
+that the biological details be thoroughly worked out for, as Howard,
+Dyar, and Knab have emphasized, "much useless labor and expense can be
+avoided by an accurate knowledge of the habits of the species." For a
+critical discussion of the known facts the reader is referred to their
+monograph. We shall confine ourselves to a few illustrations.
+
+The majority of mosquitoes in temperate climates hibernate in the egg
+stage, hatching in the spring or even mild winter days in water from
+melting snow. It is such single-brooded species which appear in
+astounding numbers in the far North. Similarly, in dry regions the eggs
+may stand thorough dessication, and yet hatch out with great promptness
+when submerged by the rains. "Another provision to insure the species
+against destruction in such a case, exists in the fact * * * that not
+all the eggs hatch, a part of them lying over until again submerged by
+subsequent rains." In temperate North America, a few species pass the
+winter in the larval state. An interesting illustration of this is
+afforded by _Wyeomia smithii_, whose larvæ live in pitcher plants and
+are to be found on the coldest winter days imbedded in the solid ice.
+Late in the spring, the adults emerge and produce several broods during
+the summer.
+
+In the United States, one of the most important facts which has been
+brought out by the intensive studies of recent years is that certain
+species are migratory and that they can travel long distances and become
+an intolerable pest many miles from their breeding places. This was
+forcibly emphasized in Dr. Smith's work in New Jersey, when he found
+that migratory mosquitoes, developing in the salt marshes along the
+coast, are the dominant species largely responsible for the fame of the
+New Jersey mosquito. The species concerned are _Aedes sollicitans_, _A.
+cantator_ and _A. tæniorhynchus_. Dr. Smith decided that the first of
+these might migrate at least forty miles inland. It is obvious that
+where such species are the dominant pest, local control measures are a
+useless waste of time and money. Such migratory habits are rare,
+however, and it is probable that the majority of mosquitoes do not fly
+any great distance from their breeding places.
+
+While mosquitoes are thought of primarily as a pest of man, there are
+many species which have never been known to feed upon human or mammalian
+blood, no matter how favorable the opportunity. According to Howard,
+Dyar, and Knab, this is true of _Culex territans_, one of the common
+mosquitoes in the summer months in the Northern United States. There are
+some species, probably many, in which the females, like the males, are
+plant feeders. In experimental work, both sexes are often kept alive for
+long periods by feeding them upon ripe banana, dried fig, raisins, and
+the like, and in spite of sweeping assertions that mosquitoes must have
+a meal of blood in order to stimulate the ovaries to development, some
+of the common blood-sucking species, notably _Culex pipiens_, have been
+bred repeatedly without opportunity to feed upon blood.
+
+The effect of the bite varies greatly with different species and depends
+upon the susceptibility of the individual bitten. Some persons are
+driven almost frantic by the attacks of the pests when their companions
+seem almost unconscious of any inconvenience. Usually, irritation and
+some degree of inflammation appear shortly following the bite. Not
+infrequently a hardened wheal or even a nodule forms, and sometimes
+scratching leads to secondary infection and serious results.
+
+The source of the poison is usually supposed to be the salivary glands
+of the insect. As we have already pointed out, (p. 34), Macloskie
+believed that one lobe of the gland, on each side, was specialized for
+forming the poison, while a radically different view is that of
+Schaudinn, who believed that the irritation is due to the expelled
+contents of the oesophageal diverticula, which contain a gas and a
+peculiar type of fungi or bacteria. In numerous attempts, Schaudinn was
+unable to produce any irritation by applying the triturated salivary
+glands to a wound, but obtained the typical result when he used the
+isolated diverticula.
+
+The irritation of the bite may be relieved to some extent by using
+ammonia water, a one per cent. alcoholic solution of menthol, or
+preparations of cresol, or carbolic acid. Dr. Howard recommends rubbing
+the bite gently with a piece of moist toilet soap. Castellani and
+Chalmers recommend cleansing inflamed bites with one in forty carbolic
+lotion, followed by dressing with boracic ointment. Of course,
+scratching should be avoided as much as possible.
+
+Repellents of various kinds are used, for warding off the attacks of the
+insects. We have often used a mixture of equal parts of oil of
+pennyroyal and kerosene, applied to the hands and face. Oil of
+citronella is much used and is less objectionable to some persons. A
+recommended formula is, oil of citronella one ounce, spirits of camphor
+one ounce, oil of cedar one-half ounce. A last resort would seem to be
+the following mixture recommended by Howard, Dyar, and Knab for use by
+hunters and fishermen in badly infested regions, against mosquitoes and
+blackflies.
+
+Take 2¼ lbs. of mutton tallow and strain it. While still hot add ½
+lb. black tar (Canadian tar). Stir thoroughly and pour into the
+receptacle in which it is to be contained. When nearly cool stir in
+three ounces of oil of citronella and 1¼ oz. of pennyroyal.
+
+At night the surest protection is a good bed net. There are many types
+of these in use, but in order to be serviceable and at the same time
+comfortable it should be roomy and hung in such a way as to be stretched
+tightly in every direction. We prefer one suspended from a broad, square
+frame, supported by a right-angled standard which is fastened to the
+head of the bed. It must be absolutely free from rents or holes and
+tucked in securely under the mattress or it will serve merely as a
+convenient cage to retain mosquitoes which gain an entrance. While such
+nets are a convenience in any mosquito ridden community, they are
+essential in regions where disease-carrying species abound. Screening of
+doors, windows and porches, against the pests is so commonly practiced
+in this country that its importance and convenience need hardly be
+urged.
+
+Destruction of mosquitoes and prevention of breeding are of fundamental
+importance. Such measures demand first, as we have seen, the correct
+determination of the species which is to be dealt with, and a knowledge
+of its life-history and habits. If it prove to be one of the migratory
+forms, it is beyond mere local effort and becomes a problem demanding
+careful organization and state control. An excellent illustration of the
+importance and effectiveness of work along these lines is afforded by
+that in New Jersey, begun by the late Dr. John B. Smith and being pushed
+with vigor by his successor, Dr. Headlee.
+
+In any case, there is necessity for community action. Even near the
+coast, where the migratory species are dominant, there are the local
+species which demand attention and which cannot be reached by any
+measures directed against the species of the salt marshes. The most
+important of local measures consist in the destruction of breeding
+places by filling or draining ponds and pools, clearing up of more
+temporary breeding places, such as cans, pails, water barrels and the
+like. Under conditions where complete drainage of swamps is
+impracticable or undesirable, judicious dredging may result in a pool or
+series of steep-sided pools deep enough to maintain a supply of fish,
+which will keep down the mosquito larvæ. Where water receptacles are
+needed for storage of rain water, they should be protected by careful
+screening or a film of kerosene over the top of the water, renewed every
+two weeks or so, so as to prevent mosquitoes from depositing their eggs.
+When kerosene is used, Water drawn from the bottom of the receptacle
+will not be contaminated by it to any injurious extent. Where ponds
+cannot be drained much good will be accomplished by spraying kerosene
+oil on the surface of the water, or by the introduction of fish which
+will feed on the larvæ.
+
+Detailed consideration of the most efficient measures for controlling
+mosquitoes is to be found in Dr. Howard's Bulletin No. 88 of the Bureau
+of Entomology, "Preventive and remedial work against mosquitoes" or, in
+more summarized form, in Farmers' Bulletin No. 444. One of these should
+be obtained by any person interested in the problems of mosquito control
+and public health.
+
+[Illustration: 74. Mouth parts of Simulium. After Grünberg.]
+
+
+The Simuliidæ, or Black Flies
+
+The SIMULIIDÆ, or black flies, are small, dark, or black flies, with a
+stout body and a hump-back appearance. The antennæ are short but
+eleven-segmented, the wings broad, without scales or hairs, and with the
+anterior veins stout but the others very weak. The mouth-parts (fig. 74)
+are fitted for biting.
+
+The larvæ of the Simuliidæ (fig. 75) are aquatic and, unlike those of
+mosquitoes, require a well ærated, or swiftly running water. Here they
+attach to stones, logs, or vegetation and feed upon various
+micro-organisms. They pupate in silken cocoons open at the top. Detailed
+life-histories have not been worked out for most of the species. We
+shall consider as typical that of _Simulium pictipes_, an inoffensive
+species widely distributed in the Eastern United States, which has been
+studied especially at Ithaca, N.Y. (Johannsen, 1903).
+
+[Illustration: 75. Larva of Simulium, (×8). After Garman.]
+
+The eggs are deposited in a compact yellowish layer on the surface of
+rock, on the brinks of falls and rapids where the water is flowing
+swiftly. They are elongate ellipsoidal in shape, about .4 by .18 mm. As
+myriads of females deposit in the same place the egg patches may be
+conspicuous coatings of a foot or much more in diameter. When first laid
+they are enveloped in a yellowish white slime, which becomes darker,
+until finally it becomes black just before the emerging of the larvæ.
+The egg stage lasts a week.
+
+The larvæ (fig. 75) are black, soft skinned, somewhat cylindrical in
+shape, enlarged at both ends and attenuated in the middle. The posterior
+half is much stouter than the anterior part and almost club-shaped. The
+head bears two large fan-shaped organs which aid in procuring food.
+Respiration is accomplished by means of three so-called blood gills
+which are pushed out from the dorsal part of the rectum. The larvæ occur
+in enormous numbers, in moss-like patches. If removed from their natural
+habitat and placed in quiet water they die within three or four hours.
+Fastened to the rock by means of a disk-like sucker at the caudal end of
+the body, they ordinarily assume an erect position. They move about on
+the surface of the rocks, to a limited extent, with a looping gait
+similar to that of a measuring worm, and a web is secreted which
+prevents their being washed away by the swiftly flowing water. They feed
+chiefly upon algæ and diatoms.
+
+The complete larval stage during the summer months occupies about four
+weeks, varying somewhat with the temperature and velocity of the water.
+At the end of this period they spin from cephalic glands, boot-shaped
+silken cocoons within which they pupate. The cocoon when spun is firmly
+attached to the rock and also to adjacent cocoons. Clustered
+continuously over a large area and sometimes one above another, they
+form a compact, carpet-like covering on the rocks, the reddish-brown
+color of which is easily distinguishable from the jet-black appearance
+of the larvæ. The pupal stage lasts about three weeks. The adult fly,
+surrounded by a bubble of air, quickly rises to the surface of the water
+and escapes. The adults (fig. 76) are apparently short lived and thus
+the entire life cycle, from egg to egg is completed in approximately
+eight weeks.
+
+[Illustration: 76. Simulium venustum, (×8). After Garman.]
+
+In the case of _Simulium pictipes_ at Ithaca, N. Y., the first brood of
+adults emerges early in May and successive generations are produced
+throughout the summer and early autumn. This species winters in the
+larval condition. Most of the other species of _Simulium_ which have
+been studied seem to be single brooded.
+
+While _Simulium pictipes_ does not attack man, there are a number of the
+species which are blood-sucking and in some regions they are a veritable
+scourge. In recent years the greatest interest in the group has been
+aroused by Sambon's hypothesis that they transmit pellagra from man to
+man. This has not been established, and, indeed, seems very doubtful,
+but the importance of these insects as pests and the possibility that
+they may carry disease make it urgent that detailed life-histories of
+the hominoxious species be worked out.
+
+As pests a vivid account of their attacks is in Agassiz's "Lake
+Superior" (p. 61), quoted by Forbes (1912).
+
+"Neither the love of the picturesque, however, nor the interests of
+science, could tempt us into the woods, so terrible were the black
+flies. This pest of flies which all the way hither had confined our
+ramblings on shore pretty closely to the rocks and the beach, and had
+been growing constantly worse, here reached its climax. Although
+detained nearly two days, * * * we could only sit with folded hands, or
+employ ourselves in arranging specimens, and such other operations as
+could be pursued in camp, and under the protection of a 'smudge.' One,
+whom scientific ardor tempted a little way up the river in a canoe,
+after water plants, came back a frightful spectacle, with blood-red
+rings round his eyes, his face bloody, and covered with punctures. The
+next morning his head and neck were swollen as if from an attack of
+erysipelas."
+
+There are even well authenticated accounts on record of death of humans
+from the attacks of large swarms of these gnats. In some regions, and
+especially in the Mississippi Valley in this country, certain species of
+black flies have been the cause of enormous losses to farmers and
+stockmen, through their attacks on poultry and domestic animals. C. V.
+Riley states that in 1874 the loss occasioned in one county in Tennessee
+was estimated at $500,000.
+
+The measures of prevention and protection against these insects have
+been well summarized by Forbes (1912). They are of two kinds: "the use
+of repellents intended to drive away the winged flies, and measures for
+the local destruction of the aquatic larvæ. The repellents used are
+either smudges, or surface applications made to keep the flies from
+biting. The black-fly will not endure a dense smoke, and the well-known
+mosquito smudge seems to be ordinarily sufficient for the protection of
+man. In the South, leather, cloth, and other materials which will make
+the densest and most stifling smoke, are often preserved for this use in
+the spring. Smudges are built in pastures for the protection of stock,
+and are kept burning before the doors of barns and stables. As the
+black-flies do not readily enter a dark room, light is excluded from
+stables as much as possible during the gnat season. If teams must be
+used in the open field while gnats are abroad, they may be protected
+against the attacks of the gnats by applying cotton-seed oil or axle
+grease to the surface, especially to the less hairy parts of the
+animals, at least twice a day. A mixture of oil and tar and, indeed,
+several other preventives, are of practical use in badly infested
+regions; but no definite test or exact comparison has been made with any
+them in a way to give a record of the precise results."
+
+"It is easy to drive the flies from houses or tents by burning pyrethrum
+powder inside; this either kills the flies or stupifies them so that
+they do not bite for some time thereafter." * * * "Oil of tar is
+commonly applied to the exposed parts of the body for the purpose of
+repelling the insects, and this preparation is supplied by the Hudson
+Bay Company to its employees. Minnesota fishermen frequently grease
+their faces and hands with a mixture of kerosene and mutton tallow for
+the same purpose." We have found a mixture of equal parts of kerosene
+and oil of pennyroyal efficient.
+
+Under most circumstances very little can be done to destroy this insect
+in its early stage, but occasionally conditions are such that a
+larvicide can be used effectively. Weed (1904), and Sanderson (1910)
+both report excellent results from the use of phinotas oil, a
+proprietary compound. The first-mentioned also found that in some places
+the larvæ could be removed by sweeping them loose in masses with stiff
+stable brooms and then catching them downstream on wire netting
+stretched in the water.
+
+
+Chironomidæ or Midges
+
+The flies of this family, commonly known as midges, resemble mosquitoes
+in form and size but are usually more delicate, and the wing-veins,
+though sometimes hairy, are not fringed with scales. The venation is
+simpler than in the mosquitoes and the veins are usually less distinct.
+
+These midges, especially in spring or autumn, are often seen in immense
+swarms arising like smoke over swamps and producing a humming noise
+which can be heard for a considerable distance. At these seasons they
+are frequently to be found upon the windows of dwellings, where they are
+often mistaken for mosquitoes.
+
+The larvæ are worm-like, but vary somewhat in form in the different
+genera. Most of them are aquatic, but a few live in the earth, in
+manure, decaying wood, under bark, or in the sap of trees, especially in
+the sap which collects in wounds.
+
+[Illustration: 77. Culicoides guttipennis; (_a_) adult, (×15); (_b_)
+head of same; (_c_) larva; (_d_) head; (_e_) pupa. After Pratt.]
+
+Of the many species of CHIRONOMIDÆ, (over eight hundred known), the vast
+majority are inoffensive. The sub-family Ceratopogoninæ, however, forms
+an exception, for some of the members of this group, known as sandflies,
+or punkies, suck blood and are particularly troublesome in the
+mountains, along streams, and at the seashore. Most of these have been
+classed under the genus _Ceratopogon_, but the group has been broken up
+into a number of genera and _Ceratopogon_, in the strict sense, is not
+known to contain any species which sucks the blood of vertebrates.
+
+THE CERATOPOGONINÆ--The Ceratopogoninæ are among the smallest of the
+Diptera, many of them being hardly a millimeter long and some not even
+so large. They are Chironomidæ in which the thorax is not prolonged over
+the head. The antennæ are filiform with fourteen (rarely thirteen)
+segments in both sexes, those of the male being brush-like. The basal
+segment is enlarged, the last segment never longer than the two
+preceding combined, while the last five are sub-equal to, or longer than
+the preceding segment. The legs are relatively stouter than in the other
+Chironomidæ. The following three genera of this subfamily are best known
+as blood suckers in this country.
+
+Of the genus _Culicoides_ there are many species occurring in various
+parts of the world. A number are known to bite man and animals and it is
+probable that all are capable of inflicting injury. In some localities
+they are called punkies, in others, sand-flies, a name sometimes also
+applied to the species of _Simulium_ and _Phlebotomus_. Owing to their
+very small size they are known by some tribes of Indians as No-see-ums.
+The larvæ are found in ponds, pools, water standing in hollow tree
+stumps, and the like. Though probably living chiefly in fresh water, we
+have found a species occurring in salt water. The larvæ are small,
+slender, legless, worm-like creatures (fig. 77_c_) with small brown head
+and twelve body segments. The pupæ (fig. 77_e_) are slender, more
+swollen at the anterior end and terminating in a forked process. They
+float nearly motionless in a vertical position, the respiratory tubes in
+contact with the surface film. The adults are all small, rarely
+exceeding 2¼ mm. in length. The wings are more or less covered with
+erect setulæ or hairs and in many species variously spotted and marked
+with iridescent blotches. The antennæ have fourteen segments, the palpi
+usually five. The wing venation and mouth-parts are shown in figures 77
+and 78. Of the twenty or more species of this genus occurring in the
+United States the following are known to bite: _C. cinctus_, _C.
+guttipennis_, _C. sanguisuga_, _C. stellifer_, _C. variipennis_, _C.
+unicolor_.
+
+[Illustration: 78. Culicoides guttipennis; mouth parts of adult. After
+Pratt.]
+
+One of the most widely distributed and commonest species in the Eastern
+States is _C. guttipennis_ (fig. 77a). It is black with brown legs, a
+whitish ring before the apex of each femur and both ends of each tibia;
+tarsi yellow, knobs of halteres yellow. Mesonotum opaque, brown, two
+vittæ in the middle, enlarging into a large spot on the posterior half,
+also a curved row of three spots in front of each wing, and the narrow
+lateral margins, light gray pruinose. Wings nearly wholly covered with
+brown hairs, gray, with markings as shown in the figure. Length one mm.
+
+_Johannseniella_ Will. is a wide-spread genus related to the foregoing.
+Its mouth-parts are well adapted for piercing and it is said to be a
+persistent blood sucker, particularly in Greenland. This genus is
+distinguished from _Culicoides_ by its bare wings, the venation (fig.
+163, c), and the longer tarsal claws. There are over twenty North
+American species.
+
+[Illustration: 79. Chrysops univittatus, (×4). After Osborn.]
+
+In the Southwestern United States, _Tersesthes torrens_ Towns. occurs, a
+little gnat which annoys horses, and perhaps man also, by its bite. It
+is related to _Culicoides_ but differs in the number of antennal
+segments and in its wing venation (fig. 163, e). The fly measures but
+two mm. in length and is blackish in color. The antennæ of the female
+have thirteen segments, the palpi but three, of which the second is
+enlarged and swollen.
+
+
+Tabanidæ or Horse-Flies
+
+The TABANIDÆ,--horse-flies, ear-flies, and deer-flies,--are well-known
+pests of cattle and horses and are often extremely annoying to man. The
+characteristics of the family and of the principal North American genera
+are given in the keys of Chapter XII. There are over 2500 recorded
+species. As in the mosquitoes, the females alone are blood suckers. The
+males are flower feeders or live on plant juices. This is apparently
+true also of the females of some of the genera.
+
+The eggs are deposited in masses on water plants or grasses and sedges
+growing in marshy or wet ground. Those of a common species of _Tabanus_
+are illustrated in figure 80, _a_. They are placed in masses of several
+hundred, light colored when first deposited but turning black. In a week
+or so the cylindrical larvæ, tapering at both ends (fig. 80, _b_),
+escape to the water, or damp earth, and lead an active, carnivorous
+life, feeding mainly on insect larvæ, and worms. In the forms which have
+been best studied the larval life is a long one, lasting for months or
+even for more than a year. Until recently, little was known concerning
+the life-histories of this group, but the studies of Hart (1895), and
+Hine (1903 +) have added greatly to the knowledge concerning North
+American forms.
+
+Many of the species attack man with avidity and are able to inflict
+painful bites, which may smart for hours. In some instances the wound is
+so considerable that blood will continue to flow after the fly has left.
+We have seen several cases of secondary infection following such bites.
+
+[Illustration: 80. (_a_) Eggs of Tabanus. Photograph by J. T. Lloyd.]
+
+[Illustration: 80. (_b_) Larva of Tabanus. Photograph by M. V. S.]
+
+The horse-flies have been definitely convicted of transferring the
+trypanosome of surra from diseased to healthy animals and there is good
+evidence that they transfer anthrax. The possibility of their being
+important agents in the conveyal of human diseases should not be
+overlooked. Indeed, Leiper has recently determined that a species of
+_Chrysops_ transfers the blood parasite _Filaria diurna_.
+
+
+Leptidæ or Snipe-Flies
+
+The family LEPTIDÆ is made up of moderate or large sized flies,
+predaceous in habit. They are sufficiently characterized in the keys of
+Chapter XII. Four blood-sucking species belonging to three genera have
+been reported. Of these _Symphoromyia pachyceras_ is a western species.
+Dr. J. C. Bradley, from personal experience, reports it as a vicious
+biter.
+
+[Illustration: 80. (_c_) Mouth parts of Tabanus. After Grünberg.]
+
+
+Oestridæ or Bot-flies
+
+To the family OESTRIDÆ belong the bot and warble-flies so frequently
+injurious to animals. The adults are large, or of medium size, heavy
+bodied, rather hairy, and usually resemble bees in appearance.
+
+The larvæ live parasitically in various parts of the body of mammals,
+such as the stomach (horse bot-fly), the subcutaneous connective tissue
+(warble-fly of cattle), or the nasal passage (sheep bot-fly or head
+maggot).
+
+There are on record many cases of the occurrence of the larvæ of
+Oestridæ as occasional parasites of man. A number of these have been
+collected and reviewed in a thesis by Mme. Pètrovskaia (1910). The
+majority of them relate to the following species.
+
+_Gastrophilus hæmorrhoidalis_, the red tailed bot-fly, is one of the
+species whose larvæ are most commonly found in the stomach of the horse.
+Schoch (1877) cites the case of a woman who suffered from a severe case
+of chronic catarrh of the stomach, and who vomited, and also passed from
+the anus, larvæ which apparently belonged to this species. Such cases
+are exceedingly rare but instances of subcutaneous infestation are
+fairly numerous. In the latter type these larvæ are sometimes the cause
+of the peculiar "creeping myasis." This is characterized at its
+beginning by a very painful swelling which gradually migrates, producing
+a narrow raised line four to twenty-five millimeters broad. When the
+larva is mature, sometimes after several months, it becomes stationary
+and a tumor is formed which opens and discharges the larva along with
+pus and serum.
+
+_Gastrophilus equi_ is the most widespread and common of the horse
+bot-flies. Portschinsky reports it as commonly causing subcutaneous
+myasis of man in Russia.
+
+_Hypoderma bovis_ (= _Oestrus bovis_), and _Hypoderma lineata_ are the
+so-called warble-flies of cattle. The latter species is the more common
+in North America but Dr. C. G. Hewitt has recently shown that _H. bovis_
+also occurs. Though warbles are very common in cattle in this country,
+the adult flies are very rarely seen. They are about half an inch in
+length, very hairy, dark, and closely resemble common honey-bees.
+
+They deposit their eggs on the hairs of cattle and the animals in
+licking themselves take in the young larvæ. These pass out through the
+walls of the oesophagus and migrate through the tissues of the animal,
+to finally settle down in the subcutaneous tissue of the back. The
+possibility of their entering directly through the skin, especially in
+case of infestation of man, is not absolutely precluded, although it is
+doubtful.
+
+For both species of _Hypoderma_ there are numerous cases on record of
+their occurrence in man. Hamilton (1893) saw a boy, six years of age,
+who had been suffering for some months from the glands on one side of
+his neck being swollen and from a fetid ulceration around the back teeth
+of the lower jaw of the same side. Three months' treatment was of no
+avail and the end seemed near; one day a white object, which was seen to
+move, was observed in the ulcer at the root of the tongue, and on being
+extracted was recognized as a full grown larva of _Hypoderma_. It was of
+usual tawny color, about half an inch long when contracted, about one
+third that thickness, and quite lively. The case resulted fatally. The
+boy had been on a dairy farm the previous fall, where probably the egg
+(or larva) was in some way taken into his mouth, and the larva found
+between the base of the tongue and the jaw suitable tissue in which to
+develop.
+
+Topsent (1901) reports a case of "creeping myasis" caused by _H.
+lineata_ in the skin of the neck and shoulders of a girl eight years of
+age. The larva travelled a distance of nearly six and a half inches. The
+little patient suffered excruciating pain in the place occupied by the
+larva.
+
+_Hypoderma diana_ infests deer, and has been known to occur in man.
+
+_Oestris ovis_, the sheep bot-fly, or head maggot, is widely distributed
+in all parts of the world. In mid-summer the flies deposit living
+maggots in the nostrils of sheep. These larvæ promptly pass up the nasal
+passages into the frontal and maxillary sinuses, where they feed on the
+mucous to be found there. In their migrations they cause great
+irritation to their host, and when present in numbers may cause vertigo,
+paroxysms, and even death. Portschinsky in an important monograph on
+this species, has discussed in detail its relation to man. He shows that
+it is not uncommon for the fly to attack man and that the minute living
+larvæ are deposited in the eyes, nostrils, lips, or mouth. A typical
+case in which the larvæ were deposited in the eye was described by a
+German oculist Kayser, in 1905. A woman brought her six year old
+daughter to him and said that the day before, about noontime, a flying
+insect struck the eye of the child and that since then she had felt a
+pain which increased towards evening. In the morning the pain ceased but
+the eye was very red. She was examined at about noon, at which time she
+was quiet and felt no pain. She was not sensitive to light, and the only
+thing noticed was a slight congestion and accumulation of secretion in
+the corner of the right eye. A careful examination of the eye disclosed
+small, active, white larvæ that crawled out from the folds of the
+conjunctiva and then back and disappeared. Five of these larvæ were
+removed and although an uncomfortable feeling persisted for a while, the
+eye became normal in about three weeks.
+
+Some of the other recorded cases have not resulted so favorably, for the
+eyesight has been seriously affected or even lost.
+
+According to Edmund and Etienne Sergent (1907), myasis caused by the
+larvæ of _Oestris ovis_ is very common among the shepherds in Algeria.
+The natives say that the fly deposits its larvæ quickly, while on the
+wing, without pause. The greatest pain is caused when these larvæ
+establish themselves in the nasal cavities. They then produce severe
+frontal headaches, making sleep impossible. This is accompanied by
+continuous secretion from the nasal cavities and itching pains in the
+sinuses. If the larvæ happen to get into the mouth, the throat becomes
+inflamed, swallowing is painful, and sometimes vomiting results. The
+diseased condition may last for from three to ten days or in the case of
+nasal infection, longer, but recovery always follows. The natives remove
+the larvæ from the eye mechanically by means of a small rag. When the
+nose is infested, tobacco fumigations are applied, and in case of throat
+infestation gargles of pepper, onion, or garlic extracts are used.
+
+_Rhinoestrus nasalis_, the Russian gad-fly, parasitizes the
+nasopharyngeal region of the horse. According to Portschinsky, it not
+infrequently attacks man and then, in all the known cases deposits its
+larvæ in the eye, only. This is generally done while the person is
+quiet, but not during sleep. The fly strikes without stopping and
+deposits its larva instantaneously. Immediately after, the victim
+experiences lancinating pains which without intermission increase in
+violence. There is an intense conjunctivitis and if the larvæ are not
+removed promptly the envelopes of the eye are gradually destroyed and
+the organ lost.
+
+[Illustration: 81. Larvæ of Dermatobia cyaniventris. After Blanchard.]
+
+[Illustration: 82. Young larva of Dermatobia cyaniventris. After
+Surcouf.]
+
+_Dermatobia cyaniventris_--This fly (fig. 83) is widely distributed
+throughout tropical America, and in its larval stage is well known as a
+parasite of man. The larvæ (figs. 81 and 82) which are known as the "ver
+macaque," "torcel," "ver moyocuil" or by several other local names,
+enter the skin and give rise to a boil-like swelling, open at the top,
+and comparable with the swelling produced by the warble fly larvæ, in
+cattle. They cause itching and occasional excruciating pain. When
+mature, nearly an inch in length, they voluntarily leave their host,
+drop to the ground and complete their development. The adult female is
+about 12 mm. in length. The face is yellow, the frons black with a
+grayish bloom; antennæ yellow, the third segment four times as long as
+the second, the arista pectinate. The thorax is bluish black with
+grayish bloom; the abdomen depressed, brilliant metallescent blue with
+violet tinge. The legs are yellowish, the squamæ and wings brownish.
+
+The different types of larvæ represented in figure 81 were formerly
+supposed to belong to different species but Blanchard regards them as
+merely various stages of the same species. It is only very recently that
+the early stage and the method by which man becomes infested were made
+known.
+
+[Illustration: 83. Dermatobia cyaniventris (×1¾). After Manson.]
+
+[Illustration: 84. Mosquito carrying eggs of Dermatobia cyaniventris.
+After Surcouf.]
+
+About 1900, Blanchard observed the presence of packets of large-sized
+eggs under the abdomen of certain mosquitoes from Central America; and
+in 1910, Dr. Moralès, of Costa Rica, declared that the Dermatobia
+deposited its eggs directly under the abdomen of the mosquito and that
+they were thus carried to vertebrates. Dr. Nunez Tovar observed the
+mosquito carriers of the eggs and placing larvæ from this source on
+animals, produced typical tumors and reared the adult flies. It remained
+for Surcouf (1913) to work out the full details. He found that the
+Dermatobia deposits its eggs in packets covered by a very viscid
+substance, on leaves. These become attached to mosquitoes of the species
+_Janthinosoma lutzi_ (fig. 84) which walk over the leaves. The eggs
+which adhere to the abdomen, remain attached and are thus transported.
+The embryo develops, but the young larva (fig. 82) remains in the egg
+until it has opportunity to drop upon a vertebrate fed upon by the
+mosquito.
+
+
+Muscidæ
+
+The following MUSCIDÆ, characterized elsewhere, deserve special mention
+under our present grouping of parasitic species. Other important species
+will be considered as facultative parasites.
+
+_Stomoxys calcitrans_, the stable-fly, or the biting house-fly, is often
+confused with _Musca domestica_ and therefore is discussed especially in
+our consideration of the latter species as an accidental carrier of
+disease. Its possible relation to the spread of infantile paralysis is
+also considered later.
+
+The _tsetse flies_, belonging to the genus _Glossina_, are African
+species of blood-sucking Muscidæ which have attracted much attention
+because of their rôle in transmitting various trypanosome diseases of
+man and animals. They are characterized in Chapter XII and are also
+discussed in connection with the diseases which they convey.
+
+_Chrysomyia macellaria_, (= _Compsomyia_), the "screw worm"-fly is one
+of the most important species of flies directly affecting man, in North
+America. It is not normally parasitic, however, and hence will be
+considered with other facultative parasites in Chapter IV.
+
+[Illustration: 85. Larva of Auchmeromyia luteola. After Graham-Smith.]
+
+[Illustration: 86. Auchmeromyia luteola (×4). After Graham-Smith.]
+
+_Auchmeromyia luteola_, the Congo floor maggot. This is a muscid of
+grewsome habits, which has a wide distribution throughout Africa. The
+fly (fig. 86) deposits its eggs on the ground of the huts of the
+natives. The whitish larvæ (fig. 85) on hatching are slightly flattened
+ventrally, and each segment bears posteriorly three foot-pads
+transversely arranged. At night the larvæ find their way into the low
+beds or couches of the natives and suck their blood. The adult flies do
+not bite man and, as far as known, the larvæ do not play any rôle in the
+transmission of sleeping sickness or other diseases.
+
+This habit of blood-sucking by muscid larvæ is usually referred to as
+peculiar to _Auchmeromyia luteola_ but it should be noted that the larvæ
+of _Protocalliphora_ frequent the nests of birds and feed upon the
+young. Mr. A. F. Coutant has studied especially the life-history and
+habits of _P. azurea_, whose larvæ he found attacking young crows at
+Ithaca, N.Y. He was unable to induce the larvæ to feed on man.
+
+[Illustration: 87. Cordylobia anthropophaga (×3). After Fülleborn.]
+
+[Illustration: 88. Larva of Cordylobia anthropophaga. After Blanchard.]
+
+_Cordylobia anthropophaga_, (_Ochromyia anthropophaga_), or Tumbu-fly
+(fig. 87) is an African species whose larvæ affect man much as do those
+of _Dermatobia cyniventris_, of Central and South America. The larva
+(fig. 88), which is known as "ver du Cayor" because it was first
+observed in Cayor, in Senegambia, develops in the skin of man and of
+various animals, such as dogs, cats, and monkeys. It is about 12 mm. in
+length, and of the form of the larvæ of other muscids. Upon the
+intermediate segments are minute, brownish recurved spines which give to
+the larva its characteristic appearance. The life-history is not
+satisfactorily worked out, but Fuller (1914), after reviewing the
+evidence believes that, as a rule, it deposits its young in the sleeping
+places of man and animals, whether such be a bed, a board, the floor, or
+the bare ground. In the case of babies, the maggots may be deposited on
+the scalp. The minute maggots bore their way painlessly into the skin.
+As many as forty parasites have been found in one individual and one
+author has reported finding more than three hundred in a spaniel puppy.
+Though their attacks are at times extremely painful, it is seldom that
+any serious results follow.
+
+
+THE SIPHONAPTERA OR FLEAS
+
+The SIPHONAPTERA, or fleas (fig. 89) are wingless insects, with highly
+chitinized and laterally compressed bodies. The mouth-parts are formed
+for piercing and sucking. Compound eyes are lacking but some species
+possess ocelli. The metamorphosis is complete.
+
+This group of parasites, concerning which little was known until
+recently, has assumed a very great importance since it was learned that
+fleas are the carriers of bubonic plague. Now over four hundred species
+are known. Of these, several species commonly attack man. The most
+common hominoxious species are _Pulex irritans_, _Xenopsylla cheopis_,
+_Ctenocephalus canis_, _Ctenocephalus felis_, _Ceratophyllus fasciatus_
+and _Dermatophilus penetrans_, but many others will feed readily on
+human blood if occasion arises.
+
+[Illustration: 89. Xenopsylla cheopis, male (×25). After Jordan and
+Rothschild.]
+
+We shall treat in this place of the general biology and habits of the
+hominoxious forms and reserve for the systematic section the discussion
+of the characteristics of the different genera.
+
+The most common fleas infesting houses in the Eastern United States are
+the cosmopolitan dog and cat fleas, _Ctenocephalus canis_ (fig. 90) and
+_C. felis_. Their life cycles will serve as typical. These two species
+have until recently been considered as one, under the name _Pulex
+serraticeps_. See figure 92.
+
+[Illustration: 90. Dog flea (×15). After Howard.]
+
+The eggs are oval, slightly translucent or pearly white, and measure
+about .5 mm. in their long diameter. They are deposited loosely in the
+hairs of the host and readily drop off as the animal moves around.
+Howard found that these eggs hatch in one to two days. The larvæ are
+elongate, legless, white, worm-like creatures. They are exceedingly
+active, and avoid the light in every way possible. They cast their first
+skin in from three to seven days and their second in from three to four
+days. They commenced spinning in from seven to fourteen days after
+hatching and the imago appeared five days later. Thus in summer, at
+Washington, the entire life cycle may be completed in about two weeks.
+(cf. fig. 91, 92).
+
+Strickland's (1914) studies on the biology of the rat flea,
+_Ceratophyllus fasciatus_, have so important a general bearing that we
+shall cite them in considerable detail.
+
+[Illustration: 91. Larva of Xenopsylla cheopis. After Bacot and
+Ridewood.]
+
+He found, to begin with, that there is a marked inherent range in the
+rate of development. Thus, of a batch of seventy-three eggs, all laid in
+the same day and kept together under the same conditions, one hatched in
+ten days; four in eleven days; twenty-five in twelve days; thirty-one in
+thirteen days; ten in fourteen days; one in fifteen days; and one in
+sixteen days. Within these limits the duration of the egg period seems
+to depend mainly on the degree of humidity. The incubation period is
+never abnormally prolonged as in the case of lice, (Warburton) and
+varying conditions of temperature and humidity have practically no
+effect on the percentage of eggs which ultimately hatch.
+
+The same investigator found that the most favorable condition for the
+larva is a low temperature, combined with a high degree of humidity; and
+that the presence of rubbish in which the larva may bury itself is
+essential to its successful development. When larvæ are placed in a
+bottle containing either wood-wool soiled by excrement, or with feathers
+or filter paper covered with dried blood they will thrive readily and
+pupate. They seem to have no choice between dried blood and powdered rat
+feces for food, and also feed readily on flea excrement. They possess
+the curious habit of always devouring their molted skins.
+
+[Illustration: 92. Head and pronotum of (_a_) dog flea; (_b_) of cat
+flea; (_c_) of hen flea. After Rothschild. (_d_) Nycteridiphilus
+(Ischnopsyllus) hexactenus. After Oudemans.]
+
+An important part of Strickland's experiments dealt with the question of
+duration of the pupal stage under the influence of temperature and with
+the longevity and habits of the adult. In October, he placed a batch of
+freshly formed cocoons in a small dish that was kept near a white rat in
+a deep glass jar in the laboratory. Two months later one small and
+feeble flea had emerged, but no more until February, four months after
+the beginning of the experiment. Eight cocoons were then dissected and
+seven more found to contain the imago fully formed but in a resting
+state. The remainder of the batch was then placed at 70° F. for one
+night, near a white rat. The next day all the cocoons were empty and the
+fleas were found on the white rat.
+
+Thus, temperature greatly influences the duration of the pupal period,
+which in _Ceratophyllus fasciatus_ averages seventeen days. Moreover,
+when metamorphosis is complete a low temperature will cause the imago to
+remain within the cocoon.
+
+Sexually mature and ovipositing fleas, he fed at intervals and kept
+alive for two months, when the experiment was discontinued. In the
+presence of rubbish in which they could bury themselves, unfed rat fleas
+were kept alive for many months, whereas in the absence of any such
+substratum they rarely lived a month. In the former case, it was found
+that the length of life is influenced to some degree by the temperature
+and humidity. In an experiment carried out at 70° F. and 45 per cent
+humidity, the fleas did not live for more than four months, while in an
+experiment at 60° F. and 70 per cent humidity they lived for at least
+seventeen months. There was no indication that fleas kept under these
+conditions sucked moisture from surrounding objects, and those kept in
+bell jars, with an extract of flea-rubbish on filter paper, did not live
+any longer than those which were not so supplied.
+
+Curiously enough, although the rat is the normal host of _Ceratophyllus
+fasciatus_, it was found that when given the choice these fleas would
+feed upon man in preference to rats. However, none of the fleas laid
+eggs unless they fed on rat blood.
+
+The experiments of Strickland on copulation and oviposition in the rat
+flea showed that fleas do not copulate until they are sexually mature
+and that, at least in the case of _Ceratophyllus fasciatus_, the
+reproductive organs are imperfectly developed for some time (more than a
+week) after emerging from the pupa. When mature, copulation takes place
+soon after the fleas have fed on their true host--the rat--but not if
+they have fed on a facultative host only, such as man. Copulation is
+always followed by oviposition within a very short time.
+
+The effect of the rat's blood on the female with regard to egg-laying,
+Strickland concludes, is stimulating rather than nutritive, as fleas
+that were without food for many months were observed to lay eggs
+immediately after one feed. Similarly, the male requires the stimulus of
+a meal of rat's blood before it displays any copulatory activity.
+
+Mitzmain (1910) has described in detail the act of biting on man, as
+observed in the squirrel flea, _Ceratophyllus acutus_. "The flea when
+permitted to walk freely on the arm selects a suitable hairy space where
+it ceases abruptly in its locomotion, takes a firm hold with the tarsi,
+projects its proboscis, and prepares to puncture the skin. A puncture is
+drilled by the pricking epipharynx, the saw-tooth mandibles
+supplementing the movement by lacerating the cavity formed. The two
+organs of the rostrum work alternately, the middle piece boring, while
+the two lateral elements execute a sawing movement. The mandibles, owing
+to their basal attachments, are, as is expressed by the advisory
+committee on plague investigations in India (_Journal of Hygiene_, vol.
+6, No. 4, p. 499), 'capable of independent action, sliding up and down
+but maintaining their relative positions and preserving the lumen of the
+aspiratory channel.' The labium doubles back, the V-shaped groove of
+this organ guiding the mandibles on either side."
+
+"The action of the proboscis is executed with a forward movement of the
+head and a lateral and downward thrust of the entire body. As the
+mouth-parts are sharply inserted, the abdomen rises simultaneously. The
+hind and middle legs are elevated, resembling oars. The forelegs are
+doubled under the thorax, the tibia and tarsi resting firmly on the
+epidermis serve as a support for the body during the feeding. The
+maxillary palpi are retracted beneath the head and thorax. The labium
+continues to bend, at first acting as a sheath for the sawing mandibles,
+and as these are more deeply inserted, it bends beneath the head with
+the elasticity of a bow, forcing the mandibles into the wound until the
+maxillæ are embedded in the skin of the victim. When the proboscis is
+fully inserted, the abdomen ceases for a time its lateral swinging."
+
+"The acute pain of biting is first felt when the mandibles have not
+quite penetrated and subsequently during each distinct movement of the
+abdomen. The swinging of the abdomen gradually ceases as it becomes
+filled with blood. The sting of the biting gradually becomes duller and
+less sensitive as feeding progresses. The movements of the elevated
+abdomen grow noticeably feebler as the downward thrusts of the springy
+bow-like labium becomes less frequent."
+
+"As the feeding process advances one can discern through the translucent
+walls of the abdomen a constant flow of blood, caudally from the
+pharynx, accompanied by a peristaltic movement. The end of the meal is
+signified in an abrupt manner. The flea shakes its entire body, and
+gradually withdraws its proboscis by lowering the abdomen and legs and
+violently twisting the head."
+
+"When starved for several days the feeding of the rat fleas is conducted
+in a rather vigorous manner. As soon as the proboscis is buried to the
+full length the abdomen is raised and there ensues a gradual lateral
+swaying motion, increasing the altitude of the raised end of the abdomen
+until it assumes the perpendicular. The flea is observed at this point
+to gain a better foothold by advancing the fore tarsi, and then,
+gradually doubling back the abdomen, it turns with extreme agility,
+nearly touching with its dorsal side the skin of the hand upon which it
+is feeding. Meanwhile, the hungry parasite feeds ravenously."
+
+"It is interesting to note the peculiar nervous action which the rodent
+fleas exhibit immediately when the feeding process is completed or when
+disturbed during the biting. Even while the rostrum is inserted to the
+fullest the parasite shakes its head spasmodically; in a twinkling the
+mouth is withdrawn and then the flea hops away."
+
+A habit of fleas which we shall see is of significance in considering
+their agency in the spread of bubonic plague, is that of ejecting blood
+from the anus as they feed.
+
+Fleas are famous for their jumping powers, and in control measures it is
+of importance to determine their ability along this line. It is often
+stated that they can jump about four inches, or, according to the Indian
+Plague Commission _Xenopsylla cheopis_ cannot hop farther than five
+inches. Mitzmain (1910) conducted some careful experiments in which he
+found that the human flea, _Pulex irritans_, was able to jump as far as
+thirteen inches on a horizontal plane. The mean average of five
+specimens permitted to jump at will was seven and three-tenths inches.
+The same species was observed to jump perpendicularly to a height of at
+least seven and three-fourths inches. Other species were not able to
+equal this record.
+
+The effect of the bite of fleas on man varies considerably according to
+the individual susceptibility. According to Patton and Cragg, this was
+borne out in a curious manner by the experiments of Chick and Martin.
+"In these, eight human hosts were tried; in seven, little or no
+irritation was produced, while in one quite severe inflammation was set
+up around each bite." Of two individuals, equally accustomed to the
+insects, going into an infested room, one may be literally tormented by
+them while the other will not notice them. Indeed it is not altogether
+a question of susceptibility, for fleas seem to have a special
+predilection for certain individuals. The typical itching wheals
+produced by the bites are sometimes followed, especially after
+scratching, by inflammatory papules.
+
+The itching can be relieved by the use of lotions of carbolic acid (2-3
+per cent), camphor, menthol lotion, or carbolated vaseline. If forced to
+sleep in an infested room, protection from attacks can be in a large
+measure gained by sprinkling pyrethrum, bubach, or California insect
+powder between the sheets. The use of camphor, menthol, or oil of
+eucalyptus, or oil of pennyroyal is also said to afford protection to a
+certain extent.
+
+In the Eastern United States the occurrence of fleas as household pests
+is usually due to infested cats and dogs which have the run of the
+house. We have seen that the eggs are not attached to the host but drop
+to the floor when they are laid. Verrill, cited by Osborn, states that
+on one occasion he was able to collect fully a teaspoonful of eggs from
+the dress of a lady in whose lap a half-grown kitten had been held for a
+short time. Patton and Cragg record seeing the inside of a hat in which
+a kitten had spent the night, so covered with flea eggs that it looked
+"as if it had been sprinkled with sugar from a sifter." It is no wonder
+that houses in which pets live become overrun with the fleas.
+
+One of the first control measures, then, consists in keeping such
+animals out of the house or in rigorously keeping them free from fleas.
+The latter can best be accomplished by the use of strong tar soap or
+Armour's "Flesope," which may be obtained from most druggists. The use
+of a three per cent solution of creolin, approximately four teaspoonfuls
+to a quart of warm water, has also been recommended. While this is
+satisfactory in the case of dogs, it is liable to sicken cats, who will
+lick their fur in an effort to dry themselves. Howard recommends
+thoroughly rubbing into the fur a quantity of pyrethrum powder. This
+partially stupifies the fleas which should be promptly swept up and
+burned.
+
+He also recommends providing a rug for the dog or cat to sleep on and
+giving this rug a frequent shaking and brushing, afterwards sweeping up
+and burning the dust thus removed.
+
+Since the larvæ of fleas are very susceptible to exposure, the use of
+bare floors, with few rugs, instead of carpets or matting, is to be
+recommended. Thorough sweeping, so as to allow no accumulation of dust
+in cracks and crevices will prove efficient. If a house is once
+infested it may be necessary to thoroughly scrub the floors with hot
+soapsuds, or to spray them with gasoline. If the latter method is
+adopted, care must be taken to avoid the possibility of fire.
+
+To clear a house of fleas Skinner recommends the use of flake
+naphthalene. In a badly infested house he took one room at a time,
+scattering on the floor five pounds of flake naphthalene, and closed it
+for twenty-four hours. It proved to be a perfect and effectual remedy
+and very inexpensive, as the naphthalene could be swept up and
+transferred to other rooms. Dr. Skinner adds, "so far as I am concerned,
+the flea question is solved and if I have further trouble I know the
+remedy. I intend to keep the dog and cat."
+
+The late Professor Slingerland very effectively used hydrocyanic acid
+gas fumigation in exterminating fleas in houses. In one case, where
+failure was reported, he found on investigation that the house had
+become thoroughly reinfested from pet cats, which had been left
+untreated. Fumigation with sulphur is likewise efficient.
+
+The fact that adult fleas are usually to be found on the floor, when not
+on their hosts, was ingeniously taken advantage of by Professor S. H.
+Gage in ridding an animal room at Cornell University of the pests. He
+swathed the legs of a janitor with sticky fly-paper and had him walk
+back and forth in the room. Large numbers of the fleas were collected in
+this manner.
+
+In some parts of the southern United States hogs are commonly infested
+and in turn infest sheds, barns and even houses. Mr. H. E. Vick informs
+us that it is a common practice to turn sheep into barn-lots and sheds
+in the spring of the year to collect in their wool, the fleas which
+abound in these places after the hogs have been turned out.
+
+It is a common belief that adult fleas are attracted to fresh meat and
+that advantage of this can be taken in trapping them. Various workers,
+notably Mitzman (1910), have shown that there is no basis for such a
+belief.
+
+
+THE TRUE CHIGGERS--The chigoes, or true chiggers, are the most
+completely parasitic of any of the fleas. Of the dozen or more known
+species, one commonly attacks man. This is _Dermatophilus penetrans_,
+more commonly known as _Sarcopsylla penetrans_ or _Pulex penetrans_.
+
+This species occurs in Mexico, the West Indies, Central and South
+America. There are no authentic records of its occurrence in the United
+States although, as Baker has pointed out, there is no reason why it
+should not become established in Florida and Texas. It is usually
+believed that Brazil was its original home. Sometime about the middle of
+the nineteenth century it was introduced into West Africa and has spread
+across that continent.
+
+The males and the immature females of _Dermatophilus penetrans_ (fig.
+93) closely resemble those of other fleas. They are very active little
+brown insects about 1-1.2 mm. in size, which live in the dust of native
+huts and stables, and in dry, sandy soil. In such places they often
+occur in enormous numbers and become a veritable plague.
+
+[Illustration: 93. Dermatophilus penetrans. Much enlarged. After
+Karsten.]
+
+They attack not only man but various animals. According to Castellani
+and Chalmers, "Perhaps the most noted feature is the way in which it
+attacks pigs. On the Gold Coast it appeared to be largely kept in
+existence by these animals. It is very easily captured in the free state
+by taking a little pig with a pale abdomen, and placing it on its back
+on the ground on which infected pigs are living. After watching a few
+moments, a black speck will appear on the pig's abdomen, and quickly
+another and another. These black specks are jiggers which can easily be
+transferred to a test tube. On examination they will be found to be
+males and females in about equal numbers."
+
+Both the males and females suck blood. That which characterizes this
+species as distinguished from other fleas attacking man is that when the
+impregnated female attacks she burrows into the skin and there swells
+until in a few days she has the size and appearance of a small pea (fig.
+94). Where they are abundant, hundreds of the pests may attack a single
+individual (fig. 95). Here they lie with the apex of the abdomen
+blocking the opening. According to Fülleborn (1908) they do not
+penetrate beneath the epidermis. The eggs are not laid in the flesh of
+the victim, as is sometimes stated, but are expelled through this
+opening. The female then dies, withers and falls away or is expelled by
+ulceration. According to Brumpt, she first quits the skin and then,
+falling to the ground, deposits her eggs. The subsequent development in
+so far as known, is like that of other fleas.
+
+[Illustration: 94. Dermatophilus penetrans, gravid female. After
+Moniez.]
+
+[Illustration: 95. Chiggers in the sole of foot of man. Manson's
+Tropical Diseases. Permission of Cassell and Co.]
+
+The chigoe usually enters between the toes, the skin about the roots of
+the nails, or the soles of the feet, although it may attack other parts
+of the body. Mense records the occurrence in folds of the epidermis, as
+in the neighborhood of the anus. They give rise to irritation and unless
+promptly and aseptically removed there often occurs pus formation and
+the development of a more or less serious abscess. Gangrene and even
+tetanus may ensue.
+
+Treatment consists in the careful removal of the insect, an operation
+more easily accomplished a day or two after its entrance, than at first,
+when it is unswollen. The ulcerated point should then be treated with
+weak carbolic acid, or tincture of iodine, or dusted thoroughly with an
+antiseptic powder.
+
+[Illustration: 96. Echidnophaga gallinacea.]
+
+[Illustration: 97. Echidnophaga gallinacea infesting head of chicken.
+After Enderlein.]
+
+Castellani and Chalmers recommend as prophylactic measures, keeping the
+house clean and keeping pigs, poultry, and cattle away therefrom. "High
+boots should be used, and especial care should be taken not to go to a
+ground floor bathroom with bare feet. The feet, especially the toes, and
+under the nails, should be carefully examined every morning to see if
+any black dots can be discovered, when the jigger should be at once
+removed, and in this way suppuration will be prevented. It is
+advisable, also, to sprinkle the floors with carbolic lotion, Jeyes'
+fluid, or with pyrethrum powder, or with a strong infusion of native
+tobacco, as recommended by Law and Castellani."
+
+_Echidnophaga gallinacea_ (fig. 96) is a widely distributed Hectopsyllid
+attacking poultry (fig. 97). It occurs in the Southern and Southwestern
+United States and has been occasionally reported as attacking man,
+especially children. It is less highly specialized than _Dermatophilus
+penetrans_, and does not ordinarily cause serious trouble in man.
+
+
+
+
+CHAPTER IV
+
+ACCIDENTAL OR FACULTATIVE PARASITES
+
+
+In addition to the many species of Arthropods which are normally
+parasitic on man and animals, there is a considerable number of those
+which may be classed as _accidental_ or _facultative_ parasites.
+
+Accidental or facultative parasites are species which are normally
+free-living, but which are able to exist as parasites when accidentally
+introduced into the body of man or other animal. A wide range of forms
+is included under this grouping.
+
+
+ACARINA
+
+A considerable number of mites have been reported as accidental or even
+normal, endoparasites of man, but the authentic cases are comparatively
+few.
+
+In considering such reports it is well to keep in mind von Siebold's
+warning that in view of the universal distribution of mites one should
+be on his guard. In vessels in which animal and other organic fluids and
+moist substances gradually dry out, mites are very abundantly found. If
+such vessels are used without very careful preliminary cleaning, for the
+reception of evacuations of the sick, or for the reception of parts
+removed from the body, such things may be readily contaminated by mites,
+which have no other relation whatever to them.
+
+Nevertheless, there is no doubt but that certain mites, normally
+free-living, have occurred as accidental parasites of man. Of these the
+most commonly met with is _Tyroglyphus siro_, the cheese-mite.
+
+_Tyroglyphus siro_ is a small mite of a whitish color. The male measures
+about 500µ long by 250µ wide, the female slightly larger. They live in
+cheese of almost any kind, especially such as is a little decayed. "The
+individuals gather together in winter in groups or heaps in the hollows
+and chinks of the cheese and there remain motionless. As soon as the
+temperature rises a little, they gnaw away at the cheese and reduce it
+to a powder. The powder is composed of excrement having the appearance
+of little grayish microscopic balls; eggs, old and new, cracked and
+empty; larvæ, nymphs, and perfect mites, cast skins and fragments of
+cheese, to which must be added numerous spores of microscopic
+fungi."--Murray.
+
+_Tyroglyphus siro_, and related species, have been found many times in
+human feces, under conditions which preclude the explanation that the
+contamination occurred outside of the body. They have been supposed to
+be the cause of dysentery, or diarrhoea, and it is probable that the
+_Acarus dysenteriæ_ of Linnæus, and Latreille, was this species.
+However, there is little evidence that the mites cause any noteworthy
+symptoms, even when taken into the body in large numbers.
+
+_Histiogaster spermaticus_ (fig. 152) is a Tyroglyphid mite which was
+reported by Trouessart (1902) as having been found in a cyst in the
+groin, adherent to the testis. When the cyst was punctured, it yielded
+about two ounces of opalescent fluid containing spermatozoa and numerous
+mites in all stages of development. The evidence indicated that a
+fecundated female mite had been introduced into the urethra by means of
+an unclean catheter. Though Trouessart reported the case as that of a
+Sarcoptid, Banks places the genus _Histiogaster_ with the Tyroglyphidæ.
+He states that our species feeds on the oyster-shell bark louse,
+possibly only after the latter is dead, and that in England a species
+feeds within decaying reeds.
+
+_Nephrophages sanguinarius_ is a peculiarly-shaped, angular mite which
+was found by Miyake and Scriba (1893) for eight successive days in the
+urine of a Japanese suffering from fibrinuria. Males, .117 mm. long by
+.079 mm. wide, females .36 mm. by. 12 mm., and eggs were found both in
+the spontaneously emitted urine and in that drawn by means of a
+catheter. All the mites found were dead. The describers regarded this
+mite as a true endoparasite, but it is more probable that it should be
+classed as an accidental parasite.
+
+
+MYRIAPODA
+
+There are on record a number of cases of myriapods occurring as
+accidental parasites of man. The subject has been treated in detail by
+Blanchard (1898 and 1902), who discussed forty cases. Since then at
+least eight additions have been made to the list.
+
+Neveau-Lamaire (1908) lists thirteen species implicated, representing
+eight different genera. Of the _Chilognatha_ there are three, _Julus
+terrestris_, _J. londinensis_ and _Polydesmus complanatus_. The
+remainder are _Chilopoda_, namely, _Lithobius forficatus_, _L.
+malenops_, _Geophilus carpophagus_, _G. electricus_, _G. similis_, _G.
+cephalicus_, _Scutigera coleoptrata_, _Himantarium gervaisi_,
+_Chætechelyne vesuviana_ and _Stigmatogaster subterraneus_.
+
+The majority of the cases relate to infestation of the nasal fossæ, or
+the frontal sinus, but intestinal infestation also occurs and there is
+one recorded case of the presence of a species in _Julus_ (fig. 13) in
+the auditory canal of a child.
+
+In the nose, the myriapods have been known to live for months and
+according to some records, even for years. The symptoms caused by their
+presence are inflammation, with or without increased flow of mucus,
+itching, more or less intense headache, and at times general symptoms
+such as vertigo, delirium, convulsions, and the like. These symptoms
+disappear suddenly when the parasites are expelled.
+
+In the intestine of man, myriapods give rise to obscure symptoms
+suggestive of infestation by parasitic worms. In a case reported by
+Verdun and Bruyant (1912), a child twenty months of age had been
+affected for fifteen days by digestive disturbances characterized by
+loss of appetite, nausea and vomiting. The latter had been particularly
+pronounced for three days, when there was discovered in the midst of the
+material expelled a living myriapod of the species _Chætechelyne
+vesuviana_. Anthelminthics had been administered without result. In some
+of the other cases, the administration of such drugs had resulted in the
+expulsion of the parasite through the anus.
+
+One of the extreme cases on record is that reported by Shipley (1914).
+Specimens of _Geophilus gorizensis_ (= _G. subterraneus_) "were vomited
+and passed by a woman of 68 years of age. Some of the centipedes emerged
+through the patient's nose, and it must be mentioned that she was also
+suffering from a round worm. One of her doctors was of the opinion that
+the centipedes were certainly breeding inside the lady's intestines, and
+as many as seven or eight, sometimes more, were daily leaving the
+alimentary canal."
+
+"According to her attendant's statements those centipedes had left the
+body in some hundreds during a period of twelve or eighteen months.
+Their presence produced vomiting and some hæmatemesis, and treatment
+with thymol, male-fern and turpentine had no effect in removing the
+creatures."
+
+The clinical details, as supplied by Dr. Theodore Thompson were as
+follows:
+
+"Examined by me July, 1912, her tongue was dry and glazed. There was
+bleeding taking place from the nose and I saw a living centipede she had
+just extracted from her nostril. Her heart, lungs and abdomen appeared
+normal. She was not very wasted, and did not think she had lost much
+flesh, nor was there any marked degree of anemia."
+
+Shipley gives the following reasons for believing it impossible that
+these centipedes could have multiplied in the patient's intestine. "The
+breeding habits of the genus _Geophilus_ are peculiar, and ill adapted
+for reproducing in such a habitat. The male builds a small web or nest,
+in which he places his sperm, and the female fertilizes herself from
+this nest or web, and when the eggs are fertilized they are again laid
+in a nest or web in which they incubate and in two or three weeks hatch
+out. The young _Geophilus_ differ but very little from the adult, except
+in size. It is just possible, but improbable, that a clutch of eggs had
+been swallowed by the host when eating some vegetables or fruit, but
+against this is the fact that the _Geophilus_ does not lay its eggs upon
+vegetables or fruit, but upon dry wood or earth. The egg-shell is very
+tough and if the eggs had been swallowed the egg-shells could certainly
+have been detected if the dejecta were examined. The specimens of the
+centipede showed very little signs of being digested, and it is almost
+impossible to reconcile the story of the patient with what one knows of
+the habits of the centipedes."
+
+In none of the observed cases have there been any clear indications as
+to the manner of infestation. It is possible that the myriapods have
+been taken up in uncooked fruit or vegetables.
+
+
+LEPIDOPTEROUS LARVÆ
+
+SCHOLECIASIS--Hope (1837) brought together six records of infestation of
+man by lepidopterous larvæ and proposed to apply the name scholeciasis
+to this type of parasitism. The clearest case was that of a young boy
+who had repeatedly eaten raw cabbage and who vomited larvæ of the
+cabbage butterfly, _Pieris brassicæ_. Such cases are extremely rare, and
+there are few reliable data relative to the subject. In this connection
+it may be noted that Spuler (1906) has described a moth whose larvæ live
+as ectoparasites of the sloth.
+
+
+COLEOPTERA
+
+CANTHARIASIS--By this term Hope designated instances of accidental
+parasitism by the larvæ or adults of beetles. Reports of such cases are
+usually scouted by parasitologists but there seems no good basis for
+wholly rejecting them. Cobbold refers to a half dozen cases of
+accidental parasitism by the larvæ of _Blaps mortisaga_. In one of
+these cases upwards of 1200 larvæ and several perfect insects were said
+to have been passed _per annum_. French (1905) reports the case of a man
+who for a considerable period voided adult living beetles of the species
+_Nitidula bipustulata_. Most of the other cases on record relate to the
+larvæ of _Dermestidæ_ (larder beetles _et al._) or _Tenebrionidæ_ (meal
+infesting species). Infestation probably occurs through eating raw or
+imperfectly cooked foods containing eggs or minute larvæ of these
+insects.
+
+[Illustration: 98. Larva of Piophila casei. Caudal aspect of larva.
+Posterior stigmata.]
+
+Brumpt cites a curious case of accidental parasitism by a coleopterous
+larva belonging to the genus _Necrobia_. This larva was extracted from a
+small tumor, several millimeters long, on the surface of the conjunctiva
+of the eye. The larvæ of this genus ordinarily live in decomposing flesh
+and cadavers.
+
+
+DIPTEROUS LARVÆ
+
+[Illustration: 99. Piophila casei. After Graham-Smith.]
+
+MYASIS--By this term (spelled also myiasis, and myiosis), is meant
+parasitism by dipterous larvæ. Such parasitism may be normal, as in the
+cases already described under the heading parasitic Diptera, or it may
+be facultative, due to free-living larvæ being accidentally introduced
+into wounds or the body-cavities of man. Of this latter type, there is a
+multitude of cases on record, relating to comparatively few species. The
+literature of the subject, like that relating to facultative parasitism
+in general, is unsatisfactory, for most of the determinations of species
+have been very loose. Indeed, so little has been known regarding the
+characteristics of the larvæ concerned that in many instances they could
+not be exactly determined. Fortunately, several workers have undertaken
+comparative studies along this line. The most comprehensive publication
+is that of Banks (1912), entitled "The structure of certain dipterous
+larvæ, with particular reference to those in human food."
+
+Without attempting an exhaustive list, we shall discuss here the more
+important species of Diptera whose larvæ are known to cause myasis,
+either external or internal. The following key will serve to determine
+those most likely to be encountered. The writers would be glad to
+examine specimens not readily identifiable, if accompanied by exact data
+relative to occurrence.
+
+_a._ Body more or less flattened, depressed; broadest in the middle,
+    each segment with dorsal, lateral, and ventral fleshy processes, of
+    which the laterals, at least, are more or less spiniferous (fig.
+    101). _Fannia_ (= _Homalomyia_).
+
+  In _F. canicularis_ the dorsal processes are nearly as long as the
+      laterals; in _F. scalaris_ the dorsal processes are short spinose
+      tubercles.
+
+_aa._ Body cylindrical, or slender conical tapering toward the head;
+    without fleshy lateral processes (fig. 105).
+
+_b._ With the posterior stigmata at the end of shorter or longer
+    tubercles, or if not placed upon tubercles, then not in pit; usually
+    without a "marginal button" and without a chitinous ring surrounding
+    the three slits; the slits narrowly or broadly oval, not bent (fig.
+    171 i). _Acalyptrate muscidæ_ and some species of _Anthomyiidæ_. To
+    this group belong the cheese skipper (_Piophila casei_, figs. 98,
+    99), the pomace-fly (_Drosophila ampelophila_), the apple maggot
+    (_Rhagoletis pomonella_), the cherry fruit fly (_Rhagoletis
+    cingulata_), the small dung fly (_Sepsis violacea_, fig. 170), the
+    beet leaf-miner (_Pegomyia vicina_, fig. 171 i), the cabbage, bean
+    and onion maggots (_Phorbia_ spp.) et. al.
+
+_bb._ Posterior stigmata of various forms, if the slits are narrowly
+    oval (fig. 171) then they are surrounded by a chitin ring which may
+    be open ventro-mesally.
+
+_c._ Integument leathery and usually strongly spinulose; larvæ
+    hypodermatic or endoparasitic. Bot flies (fig. 171, f, g,
+    k).--_Oestridæ_
+
+_cc._ Integument not leathery and (except in _Protocalliphora_) spinulæ
+    restricted to transverse patches near the incisures of the segments.
+
+_d._ The stigmal plates in a pit; the lip-like margin of the pit with a
+    number of fleshy tubercles; chitin ring of the stigma not complete;
+    open ventro-mesally, button absent (fig. 171 e). Flesh
+    flies.--_Sarcophaga_
+
+_dd._ Stigmata not in a pit.
+
+_e._ The chitin ring open ventra-mesally; button absent (fig. 171 c).
+    Screw-worm fly. _Chrysomyia_
+
+_ee._ The chitin ring closed.
+
+_f._ Slits of the posterior stigmata straight; marginal "button" present
+    (fig. 171 b); two distinct mouth hooks, fleshy tubercles around the
+    anal area. _Phormia_ (fig. 171 f), _Lucilia_ and _Calliphora_ (fig.
+    172, a, b), _Protocalliphora_ (fig. 171, j), _Cynomyia_ (fig. 171,
+    a). Blow flies, bluebottle flies. _Calliphorinæ_
+
+_ff._ Slits of the posterior stigmata sinuous or bent. Subfamily
+    Muscinæ.
+
+_g._ Slits of the posterior stigmata bent; usually two mouth hooks.
+    _Muscina stabulans_ (fig. 171, l), _Muscina similis_, _Myiospila
+    meditabunda_ (fig. 172, i), and some of the higher _Anthomyiidæ_.
+
+_gg._ Slits of the posterior stigmata sinuous; mouth hooks usually
+    consolidated into one. The house-fly (_Musca domestica_ fig. 171,
+    d), the stable fly (_Stomoxys calcitrans_), the horn fly (_Lyperosia
+    irritans_), _Pyrellia_, _Pseudopyrellia_, _Morellia_, _Mesembrina_.
+    _Polietes_, et. al. (fig. 172 in part).
+
+_Eristalis_--The larvæ of _Eristalis_ are the so-called rat-tailed
+maggots, which develop in foul water. In a few instances these larvæ
+have been known to pass through the human alimentary canal uninjured.
+Hall and Muir (1913) report the case of a boy five years of age, who had
+been ailing for ten weeks and who was under treatment for indigestion
+and chronic constipation. For some time he had vomited everything he
+ate. On administration of a vermifuge he voided one of the rat-tailed
+maggots of _Eristalis_. He admitted having drunk water from a ditch full
+of all manner of rotting matter. It was doubtless through this that he
+became infested. It is worth noting that the above described symptoms
+may have been due to other organisms or substances in the filthy water.
+
+_Piophila casei_, the cheese-fly (fig. 99), deposits its eggs not only
+in old cheeses, but on ham, bacon, and other fats. The larvæ (fig. 98)
+are the well-known cheese skippers, which sometimes occur in great
+abundance on certain kinds of cheese. Indeed, some people have a
+comfortable theory that such infested cheese is especially good. Such
+being the case, it is small wonder that this species has been repeatedly
+reported as causing intestinal myasis. Thebault (1901) describes the
+case of a girl who, shortly after consuming a large piece of badly
+infested cheese, became ill and experienced severe pains in the region
+of the navel. Later these extended through the entire alimentary canal,
+the excrement was mixed with blood and she suffered from vertigo and
+severe headaches. During the four following days the girl felt no
+change, although the excretion of the blood gradually diminished and
+stopped. On the fourth day she voided two half-digested larvæ and,
+later, seven or eight, of which two were alive and moving.
+
+That these symptoms may be directly attributed to the larvæ, or
+"skippers," has been abundantly shown by experimental evidence.
+Portschinsky cites the case of a dog fed on cheese containing the larvæ.
+The animal suffered much pain and its excrement contained blood. On
+_post mortem_ it was found that the small intestine throughout almost
+its entire length was marked by bloody bruises. The papillæ on these
+places were destroyed, although the walls were not entirely perforated.
+In the appendix were found two or three dead larvæ. Alessandri (1910)
+has likewise shown that the larvæ cause intestinal lesions.
+
+According to Graham-Smith, Austen (1912) has recorded a case of myasis
+of the nose, attended with a profuse watery discharge of several weeks
+duration and pain, due to the larvæ of _Piophila casei_.
+
+
+ANTHYOMYIIDÆ--The characteristic larvæ of two species of _Fannia_ (=
+_Homalomyia_ or _Anthomyia_, in part) (fig. 101) are the most commonly
+reported of dipterous larvæ causing intestinal myasis. Hewitt (1912) has
+presented a valuable study of the bionomics and of the larvæ of these
+flies, a type of what is needed for all the species concerned in myasis.
+We have seen two cases of their having been passed in stools, without
+having caused any special symptoms. In other instances their presence in
+the alimentary canal has given rise to symptoms vaguely described as
+those of tapeworm infestation, or helminthiasis. More specifically, they
+have been described as causing vertigo, severe headache, nausea and
+vomiting, severe abdominal pains, and in some instances, bloody
+diarrhoea.
+
+[Illustration: 100. Fannia canicularis (×4). After Graham-Smith.]
+
+One of the most striking cases is that reported by Blankmeyer (1914), of
+a woman whose illness began fourteen years previously with nausea and
+vomiting. After several months of illness she began passing larvæ and
+was compelled to resort to enemas. Three years previous to the report,
+she noticed frequent shooting pains in the rectal region and at times
+abdominal tenderness was marked. There was much mucus in the stools and
+she "experienced the sensation of larvæ crawling in the intestine."
+Occipital headaches were marked, with remissions, and constipation
+became chronic. The appetite was variable, there was a bad taste in the
+mouth, tongue furred and ridged, and red at the edges. Her complexion
+was sallow, and general nervousness was marked. As treatment, there were
+given doses of magnesium sulphate before breakfast and at 4 P. M., with
+five grain doses of salol four times a day. The customary parasiticides
+yielded no marked benefit. At the time of the report the patient passed
+from four to fifty larvæ per day, and was showing some signs of
+improvement. The nausea had disappeared, her nervousness was less
+evident, and there was a slight gain in weight.
+
+The case was complicated by various other disorders, but the symptoms
+given above seem to be in large part attributable to the myasis. There
+is nothing in the case to justify the assumption that larvæ were
+continuously present, for years. It seems more reasonable to suppose
+that something in the habits of the patient favored repeated
+infestation. Nevertheless, a study of the various cases of intestinal
+myasis caused by these and other species of dipterous larvæ seems to
+indicate that the normal life cycle may be considerably prolonged under
+the unusual conditions.
+
+The best authenticated cases of myasis of the urinary passage have been
+due to larvæ of _Fannia_. Chevril (1909) collected and described twenty
+cases, of which seven seemed beyond doubt. One of these was that of a
+woman of fifty-five who suffered from albuminuria, and urinated with
+much difficulty, and finally passed thirty to forty larvæ of _Fannia
+canicularis_.
+
+It is probable that infestation usually occurs through eating partially
+decayed fruit or vegetables on which the flies have deposited their
+eggs. Wellman points out that the flies may deposit their eggs in or
+about the anus of persons using outside privies and Hewitt believes that
+this latter method of infection is probably the common one in the case
+of infants belonging to careless mothers. "Such infants are sometimes
+left about in an exposed and not very clean condition, in consequence of
+which flies are readily attracted to them and deposit their eggs."
+
+[Illustration: 101. Larva of Fannia scalaris.]
+
+
+MUSCINÆ--The larvæ of the common house-fly, _Musca domestica_, are
+occasionally recorded as having been passed with the feces or vomit of
+man. While such cases may occur, it is probable that in most instances
+similar appearing larvæ of other insects have been mistakenly
+identified.
+
+_Muscina stabulans_ is regarded by Portschinsky (1913) as responsible
+for many of the cases of intestinal myasis attributed to other species.
+He records the case of a peasant who suffered from pains in the lower
+part of the breast and intestines, and whose stools were mixed with
+blood. From November until March he had felt particularly ill, being
+troubled with nausea and vomiting in addition to the pain in his
+intestines. In March, his physician prescribed injections of a
+concentrated solution of tannin, which resulted in the expulsion of
+fifty living larvæ of _Muscina stabulans_. Thereafter the patient felt
+much better, although he suffered from intestinal catarrh in a less
+severe form.
+
+[Illustration: 102 Muscina stabulans (×4). After Graham-Smith.]
+
+
+CALLIPHORINÆ--Closely related to the Sarcophagidæ are the
+_Calliphorinæ_, to which group belong many of the so-called "blue
+bottle" flies. Their larvæ feed upon dead animals, and upon fresh and
+cooked meat. Those of _Protocalliphora_, already mentioned, are
+ectoparasitic on living nestling birds. Larva of _Lucilia_, we have
+taken from tumors on living turtles. To this sub-family belongs also
+_Aucheromyia luteola_, the Congo floor maggot. Some of these, and at
+least the last mentioned, are confirmed, rather than faculative
+parasites. Various species of Calliphorinæ are occasionally met with as
+facultative parasites of man.
+
+[Illustration: 103. Lucilia cæsar, (×3). After Howard.]
+
+_Chrysomyia macellaria_, the screw worm fly (fig. 107), is the fly which
+is responsible for the most serious cases of human myasis in the United
+States. It is widely distributed in the United States but is especially
+abundant in the south. While the larvæ breed in decaying matter in
+general, they so commonly breed in the living flesh of animals that they
+merit rank as true parasites. The females are attracted to open wounds
+of all kinds on cattle and other animals and quickly deposit large
+numbers of eggs. Animals which have been recently castrated, dehorned,
+or branded, injured by barbed wire, or even by the attacks of ticks are
+promptly attacked in the regions where the fly abounds. Even the navel
+of young calves or discharges from the vulva of cows may attract the
+insect.
+
+[Illustration: 104. Calliphora erythrocephala, (×6). After
+Graham-Smith.]
+
+Not infrequently the fly attacks man, being attracted by an offensive
+breath, a chronic catarrh, or a purulent discharge from the ears. Most
+common are the cases where the eggs are deposited in the nostrils. The
+larvæ, which are hatched in a day or two, are provided with strong
+spines and proceed to bore into the tissues of the nose, even down into
+or through the bone, into the frontal sinus, the pharynx, larynx, and
+neighboring parts.
+
+Osborn (1896) quotes a number of detailed accounts of the attacks of the
+_Chrysomyia_ on man. A vivid picture of the symptomology of rhinal
+myasis caused by the larvæ of this fly is given by Castellani and
+Chalmers: "Some couple of days after a person suffering from a chronic
+catarrh, foul breath, or ozæna, has slept in the open or has been
+attacked by a fly when riding or driving,--_i.e._, when the hands are
+engaged--signs of severe catarrh appear, accompanied with inordinate
+sneezing and severe pain over the root of the nose or the frontal bone.
+Quickly the nose becomes swollen, and later the face also may swell,
+while examination of the nose may show the presence of the larvæ. Left
+untreated, the patient rapidly becomes worse, and pus and blood are
+discharged from the nose, from which an offensive odor issues. Cough
+appears as well as fever, and often some delirium. If the patient lives
+long enough, the septum of the nose may fall in, the soft and hard
+palates may be pierced, the wall of the pharynx may be destroyed. By
+this time, however, the course of the disease will have become quite
+evident by the larvæ dropping out of the nose, and if the patient
+continues to live all the larvæ may come away naturally."
+
+For treatment of rhinal myasis these writers recommend douching the nose
+with chloroform water or a solution of chloroform in sweet milk (10-20
+per cent), followed by douches of mild antiseptics. Surgical treatment
+may be necessary.
+
+[Illustration: 105. Larva of a flesh fly (Sarcophaga). Caudal aspect.
+Anterior stigmata. Pharyngeal skeleton.]
+
+
+SARCOPHAGIDÆ--The larvæ (fig. 105) of flies of this family usually feed
+upon meats, but have been found in cheese, oleomargerine, pickled
+herring, dead and living insects, cow dung and human feces. Certain
+species are parasitic in insects. Higgins (1890) reported an instance of
+"hundreds" of larvæ of _Sarcophaga_ being vomited by a child eighteen
+months of age. There was no doubt as to their origin for they were
+voided while the physician was in the room. There are many other reports
+of their occurrence in the alimentary canal. We have recorded elsewhere
+(Riley, 1906) a case in which some ten or twelve larvæ of _Sarcophaga_
+were found feeding on the diseased tissues of a malignant tumor. The
+tumor, a melanotic sarcoma, was about the size of a small walnut, and
+located in the small of the back of an elderly lady. Although they had
+irritated and caused a slight hæmorrhage, neither the patient nor others
+of the family knew of their presence. Any discomfort which they had
+caused had been attributed to the sarcomatous growth. The infestation
+occurred in mid-summer. It is probable that the adult was attracted by
+the odor of the discharges and deposited the living maggots upon the
+diseased tissues.
+
+[Illustration: 106. A flesh fly (Sarcophaga), (×4). After Graham-Smith.]
+
+According to Küchenmeister, _Sarcophaga carnaria_ (fig. 106), attracted
+by the odor, deposits its eggs and larvæ in the vagina of girls and
+women when they lie naked in hot summer days upon dirty clothes, or when
+they have a discharge from the vagina. In malignant inflammations of the
+eyes the larvæ even nestle under the eyelids and in Egypt, for example,
+produce a very serious addition to the effects of small-pox upon the
+cornea, as according to Pruner, in such cases perforation of the cornea
+usually takes place.
+
+[Illustration: 107. Chrysomyia macellaria, (×3).]
+
+_Wohlfartia magnifica_ is another Sarcophagid which commonly infests man
+in the regions where it is abundant. It is found in all Europe but is
+especially common in Russia, where Portschinsky has devoted much
+attention to its ravages. It deposits living larvæ in wounds, the nasal
+fossæ, the ears and the eyes, causing injuries even more revolting than
+those described for _Chrysomyia_.
+
+
+
+
+CHAPTER V
+
+ARTHROPODS AS SIMPLE CARRIERS OF DISEASE
+
+
+The fact that certain arthropods are poisonous, or may affect the health
+of man as direct parasites has always received attention in the medical
+literature. We come now to the more modern aspect of our subject,--the
+consideration of insects and other arthropods as transmitters and
+disseminators of disease.
+
+The simplest way in which arthropods may function in this capacity is as
+_simple carriers_ of pathogenic organisms. It is conceivable that any
+insect which has access to, and comes in contact with such organisms and
+then passes to the food, or drink, or to the body of man, may in a
+wholly accidental and incidental manner convey infection. That this
+occurs is abundantly proved by the work of recent years. We shall
+consider as typical the case against the house-fly, which has attracted
+so much attention, both popular and scientific. The excellent general
+treatises of Hewitt (1910), Howard (1911), and Graham-Smith (1913), and
+the flood of bulletins and popular literature render it unnecessary to
+consider the topic in any great detail.
+
+
+THE HOUSE-FLY AS A CARRIER OF DISEASE
+
+Up to the past decade the house-fly has usually been regarded as a mere
+pest. Repeatedly, however, it had been suggested that it might
+disseminate disease. We have seen that as far back as the sixteenth
+century, Mercurialis suggested that it was the agent in the spread of
+bubonic plague, and in 1658, Kircher reiterated this view. In 1871,
+Leidy expressed the opinion that flies were probably a means of
+communicating contagious diseases to a greater degree than was generally
+suspected. From what he had observed regarding gangrene in hospitals, he
+thought flies should be carefully excluded from wounds. In the same
+year, the editor of the _London Lancet_, referring to the belief that
+they play a useful rôle in purifying the air said, "Far from looking
+upon them as dipterous angels dancing attendance on Hygeia, regard them
+rather in the light of winged sponges spreading hither and thither to
+carry out the foul behests of Contagion."
+
+These suggestions attracted little attention from medical men, for it is
+only within very recent years that the charges have been supported by
+direct evidence. Before considering this evidence, it is necessary that
+we define what is meant by "house-fly" and that we then consider the
+life-history of the insect.
+
+There are many flies which are occasionally to be found in houses, but
+according to various counts, from 95 per cent to 99 per cent of these in
+warm weather in the Eastern United States belong to the one species
+_Musca domestica_ (fig. 108). This is the dominant house-fly the world
+over and is the one which merits the name. It has been well
+characterized by Schiner (1864), whose description has been freely
+translated by Hewitt, as follows:
+
+"Frons of male occupying a fourth part of the breadth of the head.
+Frontal stripe of female narrow in front, so broad behind that it
+entirely fills up the width of the frons. The dorsal region of the
+thorax dusty grey in color with four equally broad longitudinal stripes.
+Scutellum gray with black sides. The light regions of the abdomen
+yellowish, transparent, the darkest parts at least at the base of the
+ventral side yellow. The last segment and a dorsal line blackish brown.
+Seen from behind and against the light, the whole abdomen shimmering
+yellow, and only on each side of the dorsal line on each segment a dull
+transverse band. The lower part of the face silky yellow, shot with
+blackish brown. Median stripe velvety black. Antennæ brown. Palpi black.
+Legs blackish brown. Wings tinged with pale gray with yellowish base.
+The female has a broad velvety back, often reddishly shimmering frontal
+stripe, which is not broader at the anterior end than at the bases of
+the antennæ, but become so very much broader above that the light
+dustiness of the sides is entirely obliterated. The abdomen gradually
+becoming darker. The shimmering areas on the separate segments generally
+brownish. All the other parts are the same as in the male."
+
+The other species of flies found in houses in the Eastern United States
+which are frequently mistaken for the house or typhoid fly may readily
+be distinguished by the characters of the following key:
+
+_a._ Apical cell (R_5) of the wide wing open, i.e., the bounding veins
+    parallel or divergent (fig. 100). Their larvæ are flattened, the
+    intermediate body segments each fringed with fleshy, more or less
+    spinose, processes. _Fannia_
+
+  b. Male with the sides of the second and third abdominal segments
+      translucent yellowish. The larva with three pairs of nearly equal
+      spiniferous appendages on each segment, arranged in a
+      longitudinal series and in addition two pairs of series of smaller
+      processes (fig. 100) _F. canicularis_
+
+  bb. Male with blackish abdomen, middle tibia with a tubercle beyond
+      the middle. The larva with spiniferous appendages of which the
+      dorsal and ventral series are short, the lateral series long and
+      feathered (fig. 101) _F. scalaris_
+
+aa. Apical cell (R) of the wing more or less narrowed in the margin; i.
+    e., the bounding veins more or less converging (fig. 108).
+
+  b. The mouth-parts produced and pointed, fitted for piercing.
+
+    c. Palpi much shorter than the proboscis; a brownish gray fly, its
+        thorax with three rather broad whitish stripes; on each border
+        of the middle stripe and on the mesal borders of the lateral
+        stripes is a blackish brown line. Abdomen yellowish brown; on
+        the second, third and fourth segments are three brown spots
+        which may be faint or even absent. The larvæ live in dung. The
+        stable-fly (fig. 110) _Stomoxys calcitrans_
+
+    cc. Palpi nearly as long as the proboscis. Smaller species than the
+        house-fly. The horn-fly (fig. 167) _Hæmatobia irritans_
+
+  bb. Mouth-parts blunt, fitted for lapping.
+
+    c. Thorax, particularly on the sides and near the base of the wings
+        with soft golden yellow hairs among the bristles. This fly is
+        often found in the house in very early spring or even in the
+        winter. The cluster-fly, _Pollenia rudis_
+
+    cc. Thorax without golden yellow hairs among the bristles.
+
+      d. The last segment of the vein M with an abrupt angle. (fig.
+          108). The larvæ live in manure, etc. House-fly, _Musca
+          domestica_
+
+      dd. The last segment of vein M with a broad, gentle curve (fig.
+          102).
+
+        e. Eyes microscopically hairy; each abdominal segment with two
+            spots. Larvæ in dung. _Myiospila meditabunda_
+
+        ee. Eyes bare; abdomen gray and brown marbled. _Muscina_
+
+          f. With black legs and palpi. _M. assimilis_
+
+          ff. With legs more or less yellowish; palpi yellow. Larvæ in
+              decaying vegetable substances, dung, etc. _M. stabulans_
+
+It is almost universally believed that the adults of _Musca domestica_
+hibernate, remaining dormant throughout the winter in attics, around
+chimneys, and in sheltered but cold situations. This belief has been
+challenged by Skinner (1913), who maintains that all the adult flies die
+off during the fall and early winter and that the species is carried
+over in the pupal stage, and in no other way. The cluster-fly, _Pollenia
+rudis_, undoubtedly does hibernate in attics and similar situations and
+is often mistaken for the house-fly. In so far as concerns _Musca
+domestica_, the important question as to hibernation in the adult stage
+is an open one. Many observations by one of the writers (Johannsen) tend
+to confirm Dr. Skinner's conclusion, in so far as it applies to
+conditions in the latitude of New York State. Opposed, is the fact that
+various experimenters, notably Hewitt (1910) and Jepson (1909) wholly
+failed to carry pupæ through the winter.
+
+[Illustration: 108. The house or typhoid fly (Musca domestica (×4)).
+After Howard.]
+
+The house-fly breeds by preference in horse manure. Indeed, Dr. Howard,
+whose extensive studies of the species especially qualify him for
+expressing an opinion on the subject, has estimated that under ordinary
+city and town conditions, more than ninety per cent of the flies present
+in houses have come from horse stables or their vicinity. They are not
+limited to such localities, by any means, for it has been found that
+they would develop in almost any fermenting organic substance. Thus,
+they have been bred from pig, chicken, and cow manure, dirty waste
+paper, decaying vegetation, decaying meat, slaughter-house refuse,
+sawdust-sweepings, and many other sources. A fact which makes them
+especially dangerous as disease-carriers is that they breed readily in
+human excrement.
+
+The eggs are pure white, elongate ovoid, somewhat broader at the
+anterior end. They measure about one millimeter (1-25 inch) in length.
+They are deposited in small, irregular clusters, one hundred and twenty
+to one hundred and fifty from a single fly. A female may deposit as many
+as four batches in her life time. The eggs hatch in from eight to
+twenty-four hours.
+
+The newly hatched larva, or maggot (fig. 108), measures about two
+millimeters (1-12 inch) in length. It is pointed at the head end and
+blunt at the opposite end, where the spiracular openings are borne. It
+grows rapidly, molts three times and reaches maturity in from six to
+seven days, under favorable conditions.
+
+The pupal stage, like that of related flies, is passed in the old larval
+skin which, instead of being molted, becomes contracted and heavily
+chitinized, forming the so-called _puparium_ (fig. 108). The pupal stage
+may be completed in from three to six days.
+
+Thus during the warm summer months a generation of flies may be produced
+in ten to twelve days. Hewitt at Manchester, England, found the minimum
+to be eight days but states that larvæ bred in the open air in horse
+manure which had an average daily temperature of 22.5° C., occupied
+fourteen to twenty days in their development, according to the air
+temperature.
+
+After emergence, a period of time must elapse before the fly is capable
+of depositing eggs. This period has been tuned the _preoviposition_
+period. Unfortunately we have few exact data regarding this period.
+Hewitt found that the flies became sexually mature in ten to fourteen
+days after their emergence from the pupal state and four days after
+copulation they began to deposit their eggs; in other words the
+preoviposition stage was fourteen days or longer. Griffith (1908) found
+this period to be ten days. Dr. Howard believes that the time "must
+surely be shorter, and perhaps much shorter, under midsummer conditions,
+and in the freedom of the open air." He emphasizes that the point is of
+great practical importance, since it is during this period that the
+trapping and other methods of destroying the adult flies, will prove
+most useful.
+
+Howard estimates that there may be nine generations of flies a year
+under outdoor conditions in places comparable in climate to Washington.
+The number may be considerably increased in warmer climates.
+
+The rate at which flies may increase under favorable conditions is
+astounding. Various writers have given estimates of the numbers of flies
+which may develop as the progeny of a single individual, providing all
+the eggs and all the individual flies survived. Thus, Howard estimates
+that from a single female, depositing one hundred and twenty eggs on
+April 15th, there may be by September 10th, 5,598,720,000,000 adults.
+Fortunately, living forms do not produce in any such mathematical manner
+and the chief value of the figures is to illustrate the enormous
+struggle for existence which is constantly taking place in nature.
+
+Flies may travel for a considerable distance to reach food and shelter,
+though normally they pass to dwellings and other sources of food supply
+in the immediate neighborhood of their breeding places. Copeman, Howlett
+and Merriman (1911) marked flies by shaking them in a bag containing
+colored chalk. Such flies were repeatedly recovered at distances of
+eight to one thousand yards and even at a distance of seventeen hundred
+yards, nearly a mile.
+
+Hindle and Merriman (1914) continued these experiments on a large scale
+at Cambridge, England. They "do not think it likely that, as a rule,
+flies travel more than a quarter of a mile in thickly-housed areas." In
+one case a single fly was recovered at a distance of 770 yards but a
+part of this distance was across open fen-land. The surprising fact was
+brought out that flies tend to travel either _against_ or across the
+wind. The actual direction followed may be determined either directly by
+the action of the wind (positive anemotropism), or indirectly owing to
+the flies being attracted by any odor that it may convey from a source
+of food. They conclude that it is likely that the chief conditions
+favoring the disposal of flies are fine weather and a warm temperature.
+The nature of the locality is another considerable factor. Hodge (1913)
+has shown that when aided by the wind they may fly to much greater
+distances over the water. He reports that at Cleveland, Ohio, the cribs
+of the water works, situated a mile and a quarter, five miles, and six
+miles out in Lake Erie are invaded by a regular plague of flies when the
+wind blows from the city. Investigation showed that there was absolutely
+nothing of any kind in which flies could breed on the crib.
+
+The omnivorous habits of the house-fly are matters of everyday
+observation. From our view point, it is sufficient to emphasize that
+from feeding on excrement, on sputum, on open sores, or on putrifying
+matter, the flies may pass to the food or milk upon the table or to
+healthy mucous membranes, or uncontaminated wounds. There is nothing in
+its appearance to tell whether the fly that comes blithely to sup with
+you is merely unclean, or whether it has just finished feeding upon
+dejecta teeming with typhoid bacilli.
+
+[Illustration: 100. Pulvillus of foot of house-fly, showing glandular
+hairs.]
+
+The method of feeding of the house-fly has an important bearing on the
+question of its ability to transmit pathogenic organisms. Graham-Smith
+(1910) has shown that when feeding, flies frequently moisten soluble
+substances with "vomit" which is regurgitated from the crop. This is, of
+course, loaded with bacteria from previous food. When not sucked up
+again these drops of liquid dry, and produce round marks with an opaque
+center and rim and an intervening less opaque area. Fly-specks, then,
+consist of both vomit spots and feces. Graham-Smith shows a photograph
+of a cupboard window where, on an area six inches square, there were
+counted eleven hundred and two vomit marks and nine fecal deposits.
+
+From a bacteriologist's viewpoint a discussion of the possibility of a
+fly's carrying bacteria would seem superfluous. Any exposed object,
+animate or inanimate, is contaminated by bacteria and will transfer them
+if brought into contact with suitable culture media, whether such
+substance be food, or drink, open wounds, or the sterile culture media
+of the laboratory. A needle point may convey enough germs to produce
+disease. Much more readily may the house-fly with its covering of hairs
+and its sponge-like pulvilli (fig. 109) pick up and transfer bits of
+filth and other contaminated material.
+
+For popular instruction this inevitable transfer of germs by the
+house-fly is strikingly demonstrated by the oft copied illustration of
+the tracks of a fly on a sterile culture plate. Two plates of gelatine
+or, better, agar medium are prepared. Over one of these a fly (with
+wings clipped) is allowed to walk, the other is kept as a check. Both
+are put aside at room temperature, to be examined after twenty-four to
+forty-eight hours. At the end of that time, the check plate is as clear
+as ever, the one which the fly has walked is dotted with colonies of
+bacteria and fungi. The value in the experiment consists in emphasizing
+that by this method we merely render visible what is constantly
+occurring in nature.
+
+A comparable experiment which we use in our elementary laboratory work
+is to take three samples of _clean_ (preferably, sterile) fresh milk in
+sterile bottles. One of them is plugged with a pledget of cotton, into
+the second is dropped a fly from the laboratory and into the third is
+dropped a fly which has been caught feeding upon garbage or other filth.
+After a minute or two the flies are removed and the vials plugged as was
+number one. The three are then set aside at room temperature. When
+examined after twenty-four hours the milk in the first vial is either
+still sweet or has a "clean" sour odor; that of the remaining two is
+very different, for it has a putrid odor, which is usually more
+pronounced in the case of sample number three.
+
+Several workers have carried out experiments to determine the number of
+bacteria carried by flies under natural conditions. One of the most
+extended and best known of these is the series by Esten and Mason
+(1908). These workers caught flies from various sources in a sterilized
+net, placed them in a sterile bottle and poured over them a known
+quantity of sterilized water, in which they were shaken so as to wash
+the bacteria from their bodies. They found the number of bacteria on a
+single fly to range from 550 to 6,600,000. Early in the fly season the
+numbers of bacteria on flies are comparatively small, while later the
+numbers are comparatively very large. The place where flies live also
+determines largely the numbers that they carry. The lowest number, 550,
+was from a fly caught in the bacteriological laboratory, the highest
+number, 6,600,000 was the average from eighteen swill-barrel flies.
+Torrey (1912) made examination of "wild" flies from a tenement house
+district of New York City. He found "that the surface contamination of
+these 'wild' flies may vary from 570 to 4,400,000 bacteria per insect,
+and the intestinal bacterial content from 16,000 to 28,000,000."
+
+Less well known in this country is the work of Cox, Lewis, and Glynn
+(1912). They examined over four hundred and fifty naturally infected
+house-flies in Liverpool during September and early October. Instead of
+washing the flies they were allowed to swim on the surface of sterile
+water for five, fifteen, or thirty minutes, thus giving natural
+conditions, where infection occurs from vomit and dejecta of the flies,
+as well as from their bodies. They found, as might be expected, that
+flies from either insanitary or congested areas of the city contain far
+more bacteria than those from the more sanitary, less congested, or
+suburban areas. The number of aerobic bacteria from the former varied
+from 800,000 to 500,000,000 per fly and from the latter from 21,000 to
+100,000. The number of intestinal forms conveyed by flies from
+insanitary or congested areas was from 10,000 to 333,000,000 as compared
+with from 100 to 10,000 carried by flies from the more sanitary areas.
+
+Pathogenic bacteria and those allied to the food poisoning group were
+only obtained from the congested or moderately congested areas and not
+from the suburban areas, where the chances of infestation were less.
+
+The interesting fact was brought out that flies caught in milk shops
+apparently carry and obtain more bacteria than those from other shops
+with exposed food in a similar neighborhood. The writers explained this
+as probably due to the fact that milk when accessible, especially during
+the summer months, is suitable culture medium for bacteria, and the
+flies first inoculate the milk and later reinoculate themselves, and
+then more of the milk, so establishing a vicious circle.
+
+They conclude that in cities where food is plentiful flies rarely
+migrate from the locality in which they are bred, and consequently the
+number of bacteria which they carry depends upon the general standard
+of cleanliness in that locality. Flies caught in a street of modern,
+fairly high class, workmen's dwellings forming a sanitary oasis in the
+midst of a slum area, carried far less bacteria than those caught in the
+adjacent neighborhood.
+
+Thus, as the amount of dirt carried by flies in any particular locality,
+measured in the terms of bacteria, bears a definite relation to the
+habits of the people and to the state of the streets, it demonstrates
+the necessity of efficient municipal and domestic cleanliness, if the
+food of the inhabitants is to escape pollution, not only with harmless
+but also with occasional pathogenic bacteria.
+
+The above cited work is of a general nature, but, especially in recent
+years, many attempts have been made to determine more specifically the
+ability of flies to transmit pathogenic organisms. The critical reviews
+of Nuttall and Jepson (1909), Howard (1911), and Graham-Smith (1913)
+should be consulted by the student of the subject. We can only cite here
+a few of the more striking experiments.
+
+Celli (1888) fed flies on pure cultures of _Bacillus typhosus_ and
+declared that he was able to recover these organisms from the intestinal
+contents and excrement.
+
+Firth and Horrocks (1902), cited by Nuttall and Jepson, "kept _Musca
+domestica_ (also bluebottles) in a large box measuring 4 × 3 × 3 feet,
+with one side made of glass. They were fed on material contaminated with
+cultures of _B. typhosus_. Agar plates, litmus, glucose broth and a
+sheet of clean paper were at the same time exposed in the box. After a
+few days the plates and broth were removed and incubated with a positive
+result." Graham-Smith (1910) "carried out experiments with large numbers
+of flies kept in gauze cages and fed for eight hours on emulsions of _B.
+typhosus_ in syrup. After that time the infested syrup was removed and
+the flies were fed on plain syrup. _B. typhosus_ was isolated up to 48
+hours (but not later) from emulsions of their feces and from plates over
+which they walked."
+
+Several other workers, notably Hamilton (1903), Ficker (1903),
+Bertarelli (1910) Faichnie (1909), and Cochrane (1912), have isolated
+_B. typhosus_ from "wild" flies, naturally infected. The papers of
+Faichnie and of Cochrane we have not seen, but they are quoted in
+_extenso_ by Graham-Smith (1913).
+
+On the whole, the evidence is conclusive that typhoid germs not only may
+be accidentally carried on the bodies of house-flies but may pass
+through their bodies and be scattered in a viable condition in the feces
+of the fly for at least two days after feeding. Similar, results have
+been reached in experiments with cholera, tuberculosis and yaws, the
+last-mentioned being a spirochæte disease. Darling (1913) has shown that
+murrina, a trypanosome disease of horses and mules in the Canal zone is
+transmitted by house-flies which feed upon excoriated patches of
+diseased animals and then pass to cuts and galls of healthy animals.
+
+Since it is clear that flies are abundantly able to disseminate viable
+pathogenic bacteria, it is important to consider whether they have
+access to such organisms in nature. A consideration of the method of
+spread of typhoid will serve to illustrate the way in which flies may
+play an important rôle.
+
+Typhoid fever is a specific disease caused by _Bacillus typhosus_, and
+by it alone. The causative organism is to be found in the excrement and
+urine of patients suffering from the disease. More than that, it is
+often present in the dejecta for days, weeks, or even months and years,
+after the individual has recovered from the disease. Individuals so
+infested are known as "typhoid carriers" and they, together with those
+suffering from mild cases, or "walking typhoid," are a constant menace
+to the health of the community in which they are found.
+
+Human excrement is greedily visited by flies, both for feeding and for
+ovipositing. The discharges of typhoid patients, or of chronic
+"carriers," when passed in the open, in box privies, or camp latrines,
+or the like, serve to contaminate myriads of the insects which may then
+spread the germ to human food and drink. Other intestinal diseases may
+be similarly spread. There is abundant epidæmiological evidence that
+infantile diarrhoea, dysentery, and cholera may be so spread.
+
+Stiles and Keister (1913) have shown that spores of _Lamblia
+intestinalis_, a flagellate protozoan living in the human intestine, may
+be carried by house-flies. Though this species is not normally
+pathogenic, one or more species of _Entamoeba_ are the cause of a type
+of a highly fatal tropical dysentery. Concerning it, and another
+protozoan parasite of man, they say, "If flies can carry _Lamblia_
+spores measuring 10 to 7µ, and bacteria that are much smaller, and
+particles of lime that are much larger, there is no ground to assume
+that flies may not carry _Entamoeba_ and _Trichomonas_ spores."
+
+Tuberculosis is one of the diseases which it is quite conceivable may be
+carried occasionally. The sputum of tubercular patients is very
+attractive to flies, and various workers, notably Graham-Smith, have
+found that _Musca domestica_ may distribute the bacillus for several
+days after feeding on infected material.
+
+A type of purulent opthalmia which is very prevalent in Egypt is often
+said to be carried by flies. Nuttall and Jepson (1909) consider that the
+evidence regarding the spread of this disease by flies is conclusive and
+that the possibility of gonorrhoeal secretions being likewise conveyed
+cannot be denied.
+
+Many studies have been published, showing a marked agreement between the
+occurrence of typhoid and other intestinal diseases and the prevalence
+of house-flies. The most clear-cut of these are the studies of the Army
+Commission appointed to investigate the cause of epidemics of enteric
+fever in the volunteer camps in the Southern United States during the
+Spanish-American War. Though their findings as presented by Vaughan
+(1909), have been quoted very many times, they are so germane to our
+discussion that they will bear repetition:
+
+"Flies swarmed over infected fecal matter in the pits and fed upon the
+food prepared for the soldiers in the mess tents. In some instances
+where lime had recently been sprinkled over the contents of the pits,
+flies with their feet whitened with lime were seen walking over the
+food." Under such conditions it is no wonder that "These pests had
+inflicted greater loss upon American soldiers than the arms of Spain."
+
+Similar conditions prevailed in South Africa during the Boer War. Seamon
+believes that very much of the success of the Japanese in their fight
+against Russia was due to the rigid precautions taken to prevent the
+spread of disease by these insects and other means.
+
+Veeder has pointed out that the characteristics of a typical fly-borne
+epidemic of typhoid are that it occurs in little neighborhood epidemics,
+extending by short leaps from house to house, without regard to water
+supply or anything else in common. It tends to follow the direction of
+prevailing winds (cf. the conclusions of Hindle and Merriman). It occurs
+during warm weather. Of course, when the epidemic is once well under
+way, other factors enter into its spread.
+
+In general, flies may be said to be the chief agency in the spread of
+typhoid in villages and camps. In cities with modern sewer systems they
+are less important, though even under the best of such conditions, they
+are important factors. Howard has emphasized that in such cities there
+are still many uncared-for box privies and that, in addition, the
+deposition of feces overnight in uncared-for waste lots and alleys is
+common.
+
+Not only unicellular organisms, such as bacteria and protozoa, but also
+the eggs, embryos and larvæ of parasitic worms have been found to be
+transported by house-flies. Ransom (1911) has found that _Habronema
+muscæ_, a nematode worm often found in adult flies, is the immature
+stage of a parasite occurring in the stomach of the horse. The eggs or
+embryos passing out with the feces of the horse, are taken up by fly
+larvæ and carried over to the imago stage.
+
+Grassi (1883), Stiles (1889), Calandruccio (1906), and especially Nicoll
+(1911), have been the chief investigators of the ability of house-flies
+to carry the ova and embryos of human intestinal parasites. Graham-Smith
+(1913) summarizes the work along this line as follows:
+
+"It is evident from the investigations that have been quoted that
+house-flies and other species are greatly attracted to the ova of
+parasitic worms contained in feces and other materials, and make great
+efforts to ingest them. Unless the ova are too large they often succeed,
+and the eggs are deposited uninjured in their feces, in some cases up to
+the third day at least. The eggs may also be carried on their legs or
+bodies. Under suitable conditions, food and fluids may be contaminated
+with the eggs of various parasitic worms by flies, and in one case
+infection of the human subject has been observed. Feces containing
+tape-worm segments may continue to be a source of infection for as long
+as a fortnight. Up to the present, however, there is no evidence to show
+what part flies play in the dissemination of parasitic worms under
+natural conditions."
+
+Enough has been said to show that the house-fly must be dealt with as a
+direct menace to public health. Control measures are not merely matters
+of convenience but are of vital importance.
+
+Under present conditions the speedy elimination of the house-fly is
+impossible and the first thing to be considered is methods of protecting
+food and drink from contamination. The first of these methods is the
+thorough screening of doors and windows to prevent the entrance of
+flies. In the case of kitchen doors, the flies, attracted by odors, are
+likely to swarm onto the screen and improve the first opportunity for
+gaining an entrance. This difficulty can be largely avoided by
+screening-in the back porch and placing the screen door at one end
+rather than directly before the door.
+
+The use of sticky fly paper to catch the pests that gain entrance to the
+house is preferable to the various poisons often used. Of the latter,
+formalin (40 per cent formaldehyde) in the proportion of two
+tablespoonfuls to a pint of water is very efficient, if all other
+liquids are removed or covered, so that the flies must depend on the
+formalin for drink. The mixture is said to be made more attractive by
+the addition of sugar or milk, though we have found the plain solution
+wholly satisfactory, under proper conditions. It should be emphasized
+that this formalin mixture is not perfectly harmless, as so often
+stated. There are on record cases of severe and even fatal poisoning
+from the accidental drinking of solutions.
+
+When flies are very abundant in a room they can be most readily gotten
+rid of by fumigation with sulphur, or by the use of pure pyrethrum
+powder either burned or puffed into the air. Herrick (1913) recommends
+the following method: "At night all the doors and windows of the kitchen
+should be closed; fresh powder should be sprinkled over the stove, on
+the window ledges, tables, and in the air. In the morning flies will be
+found lying around dead or stupified. They may then be swept up and
+burned." This method has proved very efficaceous in some of the large
+dining halls in Ithaca.
+
+The writers have had little success in fumigating with the vapors of
+carbolic acid, or carbolic acid and gum camphor, although these methods
+will aid in driving flies from a darkened room.
+
+All of these methods are but makeshifts. As Howard has so well put it,
+"the truest and simplest way of attacking the fly problem is to prevent
+them from breeding, by the treatment or abolition of all places in which
+they can breed. To permit them to breed undisturbed and in countless
+numbers, and to devote all our energy to the problem of keeping them out
+of our dwellings, or to destroy them after they have once entered in
+spite of all obstacles, seems the wrong way to go about it."
+
+We have already seen that _Musca domestica_ breeds in almost any
+fermenting organic material. While it prefers horse manure, it breeds
+also in human feces, cow dung and that of other animals, and in refuse
+of many kinds. To efficiently combat the insect, these breeding places
+must be removed or must be treated in some such way as to render them
+unsuitable for the development of the larvæ. Under some conditions
+individual work may prove effective, but to be truly efficient there
+must be extensive and thorough coöperative efforts.
+
+Manure, garbage, and the like should be stored in tight receptacles and
+carted away at least once a week. The manure may be carted to the fields
+and spread. Even in spread manure the larvæ may continue their
+development. Howard points out that "it often happens that after a lawn
+has been heavily manured in early summer the occupants of the house will
+be pestered with flies for a time, but finding no available breeding
+place these disappear sooner or later. Another generation will not breed
+in the spread manure."
+
+Hutchinson (1914) has emphasized that the larvæ of houseflies have
+deeply engrained the habit of migrating in the prepupal stage and has
+shown that this offers an important point of attack in attempts to
+control the pest. He has suggested that maggot traps might be developed
+into an efficient weapon in the warfare against the house-fly. Certain
+it is that the habit greatly simplifies the problem of treating the
+manure for the purpose of killing the larvæ.
+
+There have been many attempts to find some cheap chemical which would
+destroy fly larvæ in horse manure without injuring the bacteria or
+reducing the fertilizing values of the manure. The literature abounds in
+recommendations of kerosene, lime, chloride of lime, iron sulphate, and
+other substances, but none of them has met the situation. The whole
+question has been gone into thoroughly by Cook, Hutchinson and Scales
+(1914), who tested practically all of the substances which have been
+recommended. They find that by far the most effective, economical, and
+practical of the substances is borax in the commercial form in which it
+is available throughout the country.
+
+"Borax increases the water-soluble nitrogen, ammonia and alkalinity of
+manure and apparently does not permanently injure the bacterial flora.
+The application of manure treated with borax at the rate of 0.62 pound
+per eight bushels (10 cubic feet) to soil does not injure the plants
+thus far tested, although its cumulative effect, if any, has not been
+determined."
+
+As their results clearly show that the substances so often recommended
+are inferior to borax, we shall quote in detail their directions for
+treating manure so as to kill fly eggs and maggots.
+
+"Apply 0.62 pound borax or 0.75 pound calcined colemanite to every 10
+cubic feet (8 bushels) of manure immediately on its removal from the
+barn. Apply the borax particularly around the outer edges of the pile
+with a flour sifter or any fine sieve, and sprinkle two or three gallons
+of water over the borax-treated manure.
+
+"The reason for applying the borax to the fresh manure immediately after
+its removal from the stable is that the flies lay their eggs on the
+fresh manure, and borax, when it comes in contact with the eggs,
+prevents their hatching. As the maggots congregate at the outer edge of
+the pile, most of the borax should be applied there. The treatment
+should be repeated with each addition of fresh manure, but when the
+manure is kept in closed boxes, less frequent applications will be
+sufficient. When the calcined colemanite is available, it may be used at
+the rate of 0.75 pound per 10 cubic feet of manure, and is a cheaper
+means of killing the maggots. In addition to the application of borax to
+horse manure to kill fly larvæ, it may be applied in the same proportion
+to other manures, as well as to refuse and garbage. Borax may also be
+applied to the floors and crevices in barns, stables, markets, etc., as
+well as to street sweepings, and water should be added as in the
+treatment of horse manure. After estimating the amount of material to be
+treated and weighing the necessary amount of borax, a measure may be
+used which will hold the proper amount, thus avoiding the subsequent
+weighings.
+
+"While it can be safely stated that no injurious action will follow the
+application of manure treated with borax at the rate of 0.62 pound for
+eight bushels, or even larger amounts in the case of some plants,
+nevertheless the borax-treated manure has not been studied in connection
+with the growth of all crops, nor has its cumulative effect been
+determined. It is therefore recommended that not more than 15 tons per
+acre of the borax-treated manure should be applied to the field. As
+truckmen use considerably more than this amount, it is suggested that
+all cars containing borax-treated manure be so marked, and that
+public-health officials stipulate in their directions for this treatment
+that not over 0.62 pound for eight bushels of manure be used, as it has
+been shown that larger amounts of borax will injure most plants. It is
+also recommended that all public-health officials and others, in
+recommending the borax treatment for killing fly eggs and maggots in
+manure, warn the public against the injurious effects of large amounts
+of borax on the growth of plants."
+
+"The amount of manure from a horse varies with the straw or other
+bedding used, but 12 or 15 bushels per week represent the approximate
+amount obtained. As borax costs from five to six cents per pound in
+100-pound lots in Washington, it will make the cost of the borax
+practically one cent per horse, per day. And if calcined colemanite is
+purchased in large shipments the cost should be considerably less."
+
+Hodge (1910) has approached the problem of fly extermination from
+another viewpoint. He believes that it is practical to trap flies out of
+doors during the preoviposition period, when they are sexually immature,
+and to destroy such numbers of them that the comparatively few which
+survive will not be able to lay eggs in sufficient numbers to make the
+next generation a nuisance. To the end of capturing them in enormous
+numbers he has devised traps to be fitted over garbage cans, into stable
+windows, and connected with the kitchen window screens. Under some
+conditions this method of attack has proved very satisfactory.
+
+One of the most important measures for preventing the spread of disease
+by flies is the abolition of the common box privy. In villages and rural
+districts this is today almost the only type to be found. It is the
+chief factor in the spread of typhoid and other intestinal diseases, as
+well as intestinal parasites. Open and exposed to myriads of flies which
+not only breed there but which feed upon the excrement, they furnish
+ideal conditions for spreading contamination. Even where efforts are
+made to cover the contents with dust, or ashes, or lime, flies may
+continue to breed unchecked. Stiles and Gardner have shown that
+house-flies buried in a screened stand-pipe forty-eight inches under
+sterile sand came to the surface. Other flies of undetermined species
+struggled up through seventy-two inches of sand.
+
+So great is the menace of the ordinary box privy that a number of
+inexpensive and simple sanitary privies have been designed for use where
+there are not modern sewer systems. Stiles and Lumsden (1911) have given
+minute directions for the construction of one of the best types, and
+their bulletin should be obtained by those interested.
+
+Another precaution which is of fundamental importance in preventing the
+spread of typhoid, is that of disinfecting all discharges from patients
+suffering with the disease. For this purpose, quick-lime is the cheapest
+and is wholly satisfactory. In chamber vessels it should be used in a
+quantity equal to that of the discharge to be treated. It should be
+allowed to act for two hours. Air-slaked lime is of no value whatever.
+Chloride of lime, carbolic acid, or formalin may be used, but are more
+expensive. Other intestinal diseases demand similar precautions.
+
+
+STOMOXYS CALCITRANS, THE STABLE-FLY--It is a popular belief that
+house-flies bite more viciously just before a rain. As a matter of
+fact, the true house-flies never bite, for their mouth-parts are not
+fitted for piercing. The basis of the misconception is the fact that a
+true biting fly, _Stomoxys calcitrans_ (fig. 110), closely resembling
+the house-fly, is frequently found in houses and may be driven in in
+greater numbers by muggy weather. From its usual habitat this fly is
+known as the "stable-fly" or, sometimes as the "biting house-fly."
+
+_Stomoxys calcitrans_ may be separated from the house-fly by the use of
+the key on p. 145. It may be more fully characterized as follows:
+
+The eyes of the male are separated by a distance equal to one-fourth of
+the diameter of the head, in the female by one-third. The frontal stripe
+is black, the cheeks and margins of the orbits silvery-white. The
+antennæ are black, the arista feathered on the upper side only. The
+proboscis is black, slender, fitted for piercing and projects forward in
+front of the head. The thorax is grayish, marked by four conspicuous,
+more or less complete black longitudinal stripes; the scutellum is
+paler; the macrochætæ are black. The abdomen is gray, dorsally with
+three brown spots on the second and third segments and a median spot on
+the fourth. These spots are more pronounced in the female. The legs are
+black, the pulvilli distinct. The wings are hyaline, the vein M_{1+2}
+less sharply curved than in the house-fly, the apical cell being thus
+more widely open (cf. fig. 110). Length 7 mm.
+
+[Illustration: 110. Stomoxys calcitrans; adult, larva, puparium and
+details, (×5). After Howard.]
+
+This fly is widely distributed, being found the world over. It was
+probably introduced into the United States, but has spread to all parts
+of the country. Bishopp (1913) regards it as of much more importance as
+a pest of domestic animals in the grain belt than elsewhere in the
+United States. The life-history and habits of this species have assumed
+a new significance since it has been suggested that it may transmit the
+human diseases, infantile paralysis and pellagra. In this country, the
+most detailed study of the fly is that of Bishopp (1913) whose data
+regarding the life cycle are as follows:
+
+The eggs like those of the house-fly, are about one mm. in length. Under
+a magnifying glass they show a distinct furrow along one side. When
+placed on any moist substance they hatch in from one to three days after
+being deposited.
+
+The larva or maggots (fig. 110) have the typical shape and actions of
+most maggots of the Muscid group. They can be distinguished from those
+of the house-fly as the stigma-plates are smaller, much further apart,
+with the slits less sinuous. Development takes place fairly rapidly when
+the proper food conditions are available and the growth is completed
+within eleven to thirty or more days.
+
+The pupa (fig. 110), like that of related flies, undergoes its
+development within the contracted and hardened last larval skin, or
+puparium. This is elongate oval, slightly thicker towards the head end,
+and one-sixth to one-fourth of an inch in length. The pupal stage
+requires six to twenty days, or in cool weather considerably longer.
+
+The life-cycle of the stable-fly is therefore considerably longer than
+that of _Musca domestica_. Bishopp found that complete development might
+be undergone in nineteen days, but that the average period was somewhat
+longer, ranging from twenty-one to twenty-five days, where conditions
+are very favorable. The longest period which he observed was forty-three
+days, though his finding of full grown larvæ and pupæ in straw during
+the latter part of March, in Northern Texas, showed that development may
+require about three months, as he considered that these stages almost
+certainly developed from eggs deposited the previous December.
+
+The favorite breeding place, where available, seems to be straw or
+manure mixed with straw. It also breeds in great numbers in
+horse-manure, in company with _Musca domestica_.
+
+Newstead considers that in England the stable-fly hibernates in the
+pupal stage. Bishopp finds that in the southern part of the United
+States there is no true hibernation, as the adults have been found to
+emerge at various times during the winter. He believes that in the
+northern United States the winter is normally passed in the larval and
+pupal stages, and that the adults which have been observed in heated
+stables in the dead of winter were bred out in refuse within the warm
+barns and were not hibernating adults.
+
+Graham-Smith (1913) states that although the stable-fly frequents stable
+manure, it is probably not an important agent in distributing the
+organisms of intestinal diseases. Bishopp makes the important
+observation that "it has never been found breeding in human excrement
+and does not frequent malodorous places, which are so attractive to the
+house-fly. Hence it is much less likely to carry typhoid and other germs
+which may be found in such places."
+
+Questions of the possible agency of _Stomoxys calcitrans_ in the
+transmission of infantile paralysis and of pellagra, we shall consider
+later.
+
+
+OTHER ARTHROPODS WHICH MAY SERVE AS SIMPLE CARRIERS OF PATHOGENIC
+ORGANISMS--It should be again emphasized that any insect which has
+access to, and comes in contact with, pathogenic organisms and then
+passes to the food, or drink, or the body of man, may serve as a simple
+carrier of disease. In addition to the more obvious illustrations, an
+interesting one is the previously cited case of the transfer of
+_Dermatobia cyaniventris_ by a mosquito (fig. 81-84). Darling (1913) has
+shown that in the tropics, the omnipresent ants may be important factors
+in the spread of disease.
+
+
+
+
+CHAPTER VI
+
+ARTHROPODS AS DIRECT INOCULATORS OF DISEASE GERMS
+
+
+We have seen that any insect which, like the house-fly, has access to
+disease germs and then comes into contact with the food or drink of man,
+may serve to disseminate disease. Moreover, it has been clearly
+established that a contaminated insect, alighting upon wounded or
+abraded surfaces, may infect them. These are instances of mere
+accidental, mechanical transfer of pathogenic organisms.
+
+Closely related are the instances of direct inoculation of disease germs
+by insects and other arthropods. In this type, a blood-sucking species
+not only takes up the germs but, passing to a healthy individual, it
+inserts its contaminated mouth-parts and thus directly inoculates its
+victim. In other words, the disease is transferred just as blood
+poisoning may be induced by the prick of a contaminated needle, or as
+the laboratory worker may inoculate an experimental animal.
+
+Formerly, it was supposed that this method of the transfer of disease by
+arthropods was a very common one and many instances are cited in the
+earlier literature of the subject. It is, however, difficult to draw a
+sharp line between such cases and those in which, on the one hand, the
+arthropod serves as a mere passive carrier or, on the other hand, serves
+as an essential host of the pathogenic organism. More critical study of
+the subject has led to the belief that the importance of the rôle of
+arthropods as direct inoculators has been much overestimated.
+
+The principal reason for regarding this phase of the subject as
+relatively unimportant, is derived from a study of the habits of the
+blood-sucking species. It is found that, in general, they are
+intermittent feeders, visiting their hosts at intervals and then
+abstaining from feeding for a more or less extended period, while
+digesting their meal. In the meantime, most species of bacteria or of
+protozoan parasites with which they might have contaminated their
+mouth-parts, would have perished, through inability to withstand drying.
+
+In spite of this, it must be recognized that this method of transfer
+does occur and must be reckoned with in any consideration of the
+relations of insects to disease. We shall first cite some general
+illustrations and shall then discuss the rôle of fleas in the spreading
+of bubonic plague, an illustration which cannot be regarded as typical,
+since it involves more than mere passive carriage.
+
+
+SOME ILLUSTRATIONS OF DIRECT INOCULATION OF DISEASE GERMS BY ARTHROPODS
+
+In discussing poisonous arthropods, we have already emphasized that
+species which are of themselves innocuous to man, may occasionally
+introduce bacteria by their bite or sting and thus cause more or less
+severe secondary symptoms. That such cases should occur, is no more than
+is to be expected. The mouth-parts or the sting of the insect are not
+sterile and the chances of their carrying pyogenic organisms are always
+present.
+
+More strictly falling in the category of transmission of disease germs
+by direct inoculation are the instances where the insect, or related
+form, feeds upon a diseased animal and passes promptly to a healthy
+individual which it infects. Of such a nature are the following:
+
+Various species of biting flies are factors in the dissemination of
+anthrax, an infectious and usually fatal disease of animals and,
+occasionally, of man. That the bacteria with which the blood of diseased
+animals teem shortly before death might be transmitted by such insects
+has long been contended, but the evidence in support of the view has
+been unsatisfactory. Recently, Mitzmain (1914) has reported a series of
+experiments which show conclusively that the disease may be so conveyed
+by a horse-fly, _Tabanus striatus_, and by the stable-fly, _Stomoxys
+calcitrans_.
+
+Mitzmain's experiments were tried with an artificially infected guinea
+pig, which died of the disease upon the third day. The flies were
+applied two and one-half hours, to a few minutes, before the death of
+the animal. With both species the infection was successfully transferred
+to healthy guinea pigs by the direct method, in which the flies were
+interrupted while feeding on the sick animal. The evidence at hand does
+not warrant the conclusion that insect transmission is the rule in the
+case of this disease.
+
+The nagana, or tsetse-fly disease of cattle is the most virulent disease
+of domestic animals in certain parts of Africa. It is caused by a
+protozoan blood parasite, _Trypanosoma brucei_, which is conveyed to
+healthy animals by the bite of _Glossina morsitans_ and possibly other
+species of tsetse-flies. The flies remain infective for forty-eight
+hours after feeding on a diseased animal. The insect also serves as an
+essential host of the parasite.
+
+Surra, a similar trypanosomiasis affecting especially horses and mules,
+occurs in southern Asia, Malaysia, and the Philippines where the
+tsetse-flies are not to be found. It is thought to be spread by various
+species of blood-sucking flies belonging to the genera _Stomoxys_,
+_Hæmatobia_, and _Tabanus_. Mitzmain (1913) demonstrated that in the
+Philippines it is conveyed mechanically by _Tabanus striatus_.
+
+The sleeping sickness of man, in Africa, has also been supposed to be
+directly inoculated by one, or several, species of tsetse-flies. It is
+now known that the fly may convey the disease for a short time after
+feeding, but that there is then a latent period of from fourteen to
+twenty-one days, after which it again becomes infectious. This indicates
+that in the meantime the parasite has been undergoing some phase of its
+life-cycle and that the fly serves as an intermediate host. We shall
+therefore consider it more fully under that grouping.
+
+These are a few of the cases of direct inoculation which may be cited as
+of the simpler type. We shall next consider the rôle of the flea in the
+dissemination of the bubonic plague, an illustration complicated by the
+fact that the bacillus multiples within the insect and may be indirectly
+inoculated.
+
+
+THE RÔLE OF FLEAS IN THE TRANSMISSION OF THE PLAGUE
+
+The plague is a specific infectious disease caused by _Bacillus pestis_.
+It occurs in several forms, of which the bubonic and the pneumonic are
+the most common. According to Wyman, 80 per cent of the human cases are
+of the bubonic type. It is a disease which, under the name of oriental
+plague, the pest, or the black death, has ravaged almost from time
+immemorial the countries of Africa, Asia, and Europe. The record of its
+ravages are almost beyond belief. In 542 A. D. it caused in one day ten
+thousand deaths in Constantinople. In the 14th century it was introduced
+from the East and prevailed throughout Armenia, Asia Minor, Egypt and
+Northern Africa and Europe. Hecker estimates that one-fourth of the
+population of Europe, or twenty-five million persons, died in the
+epidemic of that century. From then until the 17th century it was almost
+constantly present in Europe, the great plague of London, in 1665
+killing 68,596 out of a population of 460,000. Such an epidemic would
+mean for New York City a proportionate loss of over 600,000 in a single
+year. It is little wonder that in the face of such an appalling disaster
+suspicion and credulity were rife and the wildest demoralization ensued.
+
+During the 14th century the Jews were regarded as responsible for the
+disease, through poisoning wells, and were subjected to the most
+incredible persecution and torture. In Milan the visitation of 1630 was
+credited to the so-called anointers,--men who were supposed to spread
+the plague by anointing the walls with magic ointment--and the most
+horrible tortures that human ingenuity could devise were imposed on
+scores of victims, regardless of rank or of public service (fig. 112,
+a). Manzoni's great historical novel, "The Betrothed" has well pictured
+conditions in Italy during this period.
+
+[Illustration: 111. A contemporaneous engraving of the pest hospital in
+Vienna in 1679. After Peters.]
+
+In modern times the plague is confined primarily to warm climates, a
+condition which has been brought about largely through general
+improvement in sanitary conditions.
+
+At present, the hotbed of the disease is India, where there were
+1,040,429 deaths in 1904 and where in a period of fifteen years, ending
+with January 1912, there were over 15,000,000 deaths. The reported
+deaths in that country for 1913 totaled 198,875.
+
+During the winter of 1910-11 there occurred in Manchuria and North China
+a virulent epidemic of the pneumonic plague which caused the death of
+nearly 50,000 people. The question as to its origin and means of spread
+will be especially referred to later.
+
+[Illustration: 112 a. A medieval method of combating the plague. The
+persecution of the anointers in Milan in 1630. From a copy of "Il
+processi originale degli untori" in the library of Cornell University.]
+
+Until recent years, the plague had not been known to occur in the New
+World but there were outbreaks in Brazil and Hawaii in 1899, and in 1900
+there occurred the first cases in San Francisco. In California there
+were 125 cases in the period 1900-04; three cases in the next three
+years and then from May 1907 to March 1908, during the height of the
+outbreak, 170 cases. Since that time there have been only sporadic
+cases, the last case reported being in May 1914. Still more recent were
+the outbreaks in the Philippine Islands, Porto Rico, and Cuba.
+
+On June 24, 1914, there was recognized a case of human plague in New
+Orleans. The Federal Health Service immediately took charge, and
+measures for the eradication of the disease were vigorously enforced. Up
+to October 10, 1914 there had been reported 30 cases of the disease in
+man, and 181 cases of plague in rats.
+
+[Illustration: 112 b. The modern method of combating the plague. A day's
+catch of rats in the fight against plague in San Francisco. Courtesy of
+Review of Reviews.]
+
+The present-day methods of combating bubonic plague are well illustrated
+by the fight in San Francisco. Had it not been for the strenuous and
+radical anti-plague campaign directed by the United States Marine
+Hospital Service we might have had in our own country an illustration of
+what the disease can accomplish. On what newly acquired knowledge was
+this fight based?
+
+The basis was laid in 1894, when the plague bacillus was first
+discovered. All through the centuries, before and during the Christian
+era, down to 1894, the subject was enveloped in darkness and there had
+been a helpless, almost hopeless struggle in ignorance on the part of
+physicians, sanitarians, and public health officials against the ravages
+of this dread disease. Now its cause, method of propagation and means to
+prevent its spread are matters of scientific certainty.
+
+After the discovery of the causative organism, one of the first advances
+was the establishment of the identity of human plague and that of
+rodents. It had often been noted that epidemics of the human disease
+were preceded by great epizootics among rats and mice. So well
+established was this fact that with the Chinese, unusual mortality among
+these rodents was regarded as foretelling a visitation of the human
+disease. That there was more than an accidental connection between the
+two was obvious when Yersin, the discoverer of _Bacillus pestis_,
+announced that during an epidemic the rats found dead in the houses and
+in the streets almost always contain the bacillus in great abundance in
+their organs, and that many of them exhibit veritable buboes.
+
+Once it was established that the diseases were identical, the attention
+of the investigators was directed to a study of the relations between
+that of rats and of humans, and evidence accumulated to show that the
+bubonic plague was primarily a disease of rodents and that in some
+manner it was conveyed from them to man.
+
+There yet remained unexplained the method of transfer from rat to man.
+As long ago as the 16th century, Mercuralis suggested that house-flies
+were guilty of disseminating the plague but modern investigation, while
+blaming the fly for much in the way of spreading disease, show that it
+is an insignificant factor in this case.
+
+Search for blood-sucking insects which would feed on both rodents and
+man, and which might therefore be implicated, indicated that the fleas
+most nearly met the conditions. At first it was urged that rat fleas
+would not feed upon man and that the fleas ordinarily attacking man
+would not feed upon rats. More critical study of the habits of fleas
+soon showed that these objections were not well-founded. Especially
+important was the evidence that soon after the death of their host, rat
+fleas deserted its body and might then become a pest in houses where
+they had not been noticed before.
+
+Attention was directed to the fact that while feeding, fleas are in the
+habit of squirting blood from the anus and that in the case of those
+which had fed upon rats and mice dying of the plague, virulent plague
+bacilli were to be found in such blood. Liston (1905) even found, and
+subsequent investigations confirmed, that the plague bacilli multiply in
+the stomach of the insect and that thus the blood ejected was richer in
+the organisms than was that of the diseased animal. It was found that a
+film of this infected blood spread out under the body of the flea and
+that thus the bacilli might be inoculated by the bite of the insect and
+by scratching.
+
+Very recently, Bacot and Martin (1914) have paid especial attention to
+the question of the mechanism of the transmission of the plague bacilli
+by fleas. They believe that plague infested fleas regurgitate blood
+through the mouth, and that under conditions precluding the possibility
+of infection by dejecta, the disease may be thus transmitted. The
+evidence does not seem sufficient to establish that this is the chief
+method of transmission.
+
+Conclusive experimental proof that fleas transmit the disease is further
+available from a number of sources. The most extensive series of
+experiments is that of the English Plague Commission in India, which
+reported in 1906 that:
+
+On thirty occasions a healthy rat contracted plague in sequence of
+living in the neighborhood of a plague infected rat under circumstances
+which prevented the healthy rat coming in contact with either the body
+or excreta of the diseased animal.
+
+In twenty-one experiments out of thirty-eight, healthy rats living in
+flea-proof cages contracted plague when exposed to rat fleas
+(_Xenopsylla cheopis_), collected from rats dead or dying of septicæmic
+plague.
+
+Close contact of plague-infected with healthy animals, if fleas are
+excluded, does not give rise to an epizootic among the latter. As the
+huts were never cleaned out, close contact included contact with feces
+and urine of infected animals, and contact with, and eating of food
+contaminated with feces and urine of infected animals, as well as pus
+from open plague ulcers. Close contact of young, even when suckled by
+plague-infected mothers, did not give the disease to the former.
+
+If fleas are present, then the epizootic, once started, spreads from
+animal to animal, the rate of progress being in direct proportion to the
+number of fleas.
+
+Aerial infection was excluded. Thus guinea-pigs suspended in a cage two
+feet above the ground did not contract the disease, while in the same
+hut those animals allowed to run about and those placed two inches above
+the floor became infected. It had previously been found that a rat flea
+could not hop farther than about five inches.
+
+Guinea pigs and monkeys were placed in plague houses in pairs, both
+protected from soil contact infection and both equally exposed to aerial
+infection, but one surrounded with a layer of tangle-foot paper and the
+other surrounded with a layer of sand. The following observations were
+made:
+
+(_a_) Many fleas were caught in the tangle-foot, a certain proportion of
+which were found on dissection to contain in their stomachs abundant
+bacilli microscopically identical with plague bacilli. Out of
+eighty-five human fleas dissected only one contained these bacilli,
+while out of seventy-seven rat fleas twenty-three were found thus
+infected.
+
+(_b_) The animals surrounded with tangle-foot in no instance developed
+plague, while several (24 per cent) of the non-protected animals died of
+the disease.
+
+Thus, the experimental evidence that fleas transmit the plague from rat
+to rat, from rats to guinea pigs, and from rats to monkeys is
+indisputable. There is lacking direct experimental proof of its transfer
+from rodents to man but the whole chain of indirect evidence is so
+complete that there can be no doubt that such a transfer does occur so
+commonly that in the case of bubonic plague it must be regarded as the
+normal method.
+
+Rats are not the only animals naturally attacked by the plague but as
+already suggested, it occurs in various other rodents. In California the
+disease has spread from rats to ground squirrels (_Otospermophilus
+beecheyi_), a condition readily arising from the frequency of
+association of rats with the squirrels in the neighborhood of towns, and
+from the fact that the two species of fleas found on them are also found
+on rats. While the danger of the disease being conveyed from squirrels
+to man is comparatively slight, the menace in the situation is that the
+squirrels may become a more or less permanent reservoir of the disease
+and infect rats, which may come into more frequent contact with man.
+
+The tarbagan (_Arctomys bobac_), is a rodent found in North Manchuria,
+which is much prized for its fur. It is claimed that this animal is
+extremely susceptible to the plague and there is evidence to indicate
+that it was the primary source of the great outbreak of pneumonic plague
+which occurred in Manchuria and North China during the winter of
+1910-11.
+
+Of fleas, any species which attacks both rodents and man may be an agent
+in the transmission of the plague. We have seen that in India the
+species most commonly implicated is the rat flea, _Xenopsylla cheopis_,
+(= _Loemopsylla_ or _Pulex cheopis_) (fig. 89). This species has also
+been found commonly on rats in San Francisco. The cat flea,
+_Ctenocephalus felis_, the dog flea, _Ctenocephalus canis_, the human
+flea, _Pulex irritans_, the rat fleas, _Ceratophyllus fasciatus_ and
+_Ctenopsyllus musculi_ have all been shown to meet the conditions.
+
+But, however clear the evidence that fleas are the most important agent
+in the transfer of plague, it is a mistake fraught with danger to assume
+that they are the only factor in the spread of the disease. The
+causative organism is a bacillus and is not dependent upon any insect
+for the completion of its development.
+
+Therefore, any blood-sucking insect which feeds upon a plague infected
+man or animal and then passes to a healthy individual, conceivably might
+transfer the bacilli. Verjbitski (1908) has shown experimentally that
+bed-bugs may thus convey the disease. Hertzog found the bacilli in a
+head-louse, _Pediculus humanus_, taken from a child which had died from
+the plague, and McCoy found them in a louse taken from a plague-infected
+squirrel. On account of their stationary habits, the latter insects
+could be of little significance in spreading the disease.
+
+Contaminated food may also be a source of danger. While this source,
+formerly supposed to be the principal one, is now regarded as
+unimportant, there is abundant experimental evidence to show that it
+cannot be disregarded. It is believed that infection in this way can
+occur only when there is some lesion in the alimentary canal.
+
+Still more important is the proof that in pneumonic plague the patient
+is directly infective and that the disease is spread from man to man
+without any intermediary. Especially conclusive is the evidence obtained
+by Drs. Strong and Teague during the Manchurian epidemic of 1910-11.
+They found that during coughing, in pneumonic plague cases, even when
+sputum visible to the naked eye is not expelled, plague bacilli in large
+numbers may become widely disseminated into the surrounding air. By
+exposing sterile plates before patients who coughed a single time, very
+numerous colonies of the bacillus were obtained.
+
+But the great advance which has been made rests on the discovery that
+bubonic plague is in the vast majority of cases transmitted by the flea.
+The pneumonic type forms a very small percentage of the human cases and
+even with it, the evidence indicates that the original infection is
+derived from a rodent through the intermediary of the insect.
+
+So modern prophylactic measures are directed primarily against the rat
+and fleas. Ships coming from infected ports are no longer disinfected
+for the purpose of killing the plague germs, but are fumigated to
+destroy the rats and the fleas which they might harbor. When anchored at
+infected ports, ships must observe strenuous precautions to prevent the
+ingress of rats. Cargo must be inspected just before being brought on
+board, in order to insure its freedom from rats. Even lines and hawsers
+must be protected by large metal discs or funnels, for rats readily run
+along a rope to reach the ship. Once infested, the ship must be
+thoroughly fumigated, not only to avoid carrying the disease to other
+ports but to obviate an outbreak on board.
+
+When an epidemic begins, rats must be destroyed by trapping and
+poisoning. Various so-called biological poisons have not proved
+practicable. Sources of food supply should be cut off by thorough
+cleaning up, by use of rat-proof garbage cans and similar measures. Hand
+in hand with these, must go the destruction of breeding places, and the
+rat-proofing of dwellings, stables, markets, warehouses, docks and
+sewers. All these measures are expensive, and a few years ago would have
+been thought wholly impossible to put into practice but now they are
+being enforced on a large scale in every fight against the disease.
+
+Rats and other rodents are regularly caught in the danger zone and
+examined for evidence of infection, for the sequence of the epizootic
+and of the human disease is now understood. In London, rats are
+regularly trapped and poisoned in the vicinity of the principal docks,
+to guard against the introduction of infected animals in shipping.
+During the past six years infected rats have been found yearly, thirteen
+having been found in 1912. In Seattle, Washington, seven infected rats
+were found along the water front in October, 1913, and infected ground
+squirrels are still being found in connection with the anti-plague
+measures in California.
+
+The procedure during an outbreak of the human plague was well
+illustrated by the fight in San Francisco. The city was districted, and
+captured rats, after being dipped in some fluid to destroy the fleas,
+were carefully tagged to indicate their source, and were sent to the
+laboratory for examination. If an infected rat was found, the officers
+in charge of the work in the district involved were immediately notified
+by telephone, and the infected building was subjected to a thorough
+fumigation. In addition, special attention was given to all the
+territory in the four contiguous blocks.
+
+By measures such as these, this dread scourge of the human race is being
+brought under control. Incidentally, the enormous losses due to the
+direct ravages of rats are being obviated and this alone would justify
+the expenditure many times over of the money and labor involved in the
+anti-rat measures.
+
+
+
+
+CHAPTER VII
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC ORGANISMS
+
+
+We now have to consider the cases in which the arthropod acts as the
+essential host of a pathogenic organism. In other words, cases in which
+the organism, instead of being passively carried or merely accidentally
+inoculated by the bite of its carrier, or vector, is taken up and
+undergoes an essential part of its development within the arthropod.
+
+[Illustration: 113. Dipylidium caninum. The double pored tapeworm of the
+dog.]
+
+In some cases, the sexual cycle of the parasite is undergone in the
+arthropod, which then serves as the _definitive_ or _primary host_. In
+other cases, it is the asexual stage of the parasite which is undergone,
+and the arthropod then acts as the _intermediate host_. This distinction
+is often overlooked and all the cases incorrectly referred to as those
+in which the insect or other arthropod acts as intermediate host.
+
+We have already emphasized that this is the most important way in which
+insects may transmit disease, for without them the particular organisms
+concerned could never complete their development. Exterminate the
+arthropod host and the life cycle of the parasite is broken, the disease
+is exterminated.
+
+As the phenomenon of alternation of generations, as exhibited by many of
+the parasitic protozoa, is a complicated one and usually new to the
+student, we shall first take up some of the grosser cases illustrated by
+certain parasitic worms. There is the additional reason that these were
+the first cases known of arthropod transmission of pathogenic organisms.
+
+
+INSECTS AS INTERMEDIATE HOSTS OF TAPEWORMS
+
+A number of tapeworms are known to undergo their sexual stage in an
+insect or other arthropod. Of these at least two are occasional
+parasites of man.
+
+_Dipylidium caninum_ (figs. 113 and 114), more generally known as
+_Taenia cucumerina_ or _T. elliptica_, is the commonest intestinal
+parasite of pet dogs and cats. It is occasionally found as a human
+parasite, 70 per cent of the cases reported being in young children.
+
+In 1869, Melnikoff found in a dog louse, _Trichodectes canis_, some
+peculiar bodies which Leuckart identified as the larval form of this
+tapeworm. The worm is, however, much more common in dogs and cats than
+is the skin parasite, and hence it appears that the _Trichodectes_ could
+not be the only intermediate host. In 1888, Grassi found that it could
+also develop in the cat and dog fleas, _Ctenocephalus felis_ and _C.
+canis_, and in the human flea, _Pulex irritans_.
+
+[Illustration: 114. Dipylidium caninum. Rostrum evaginated and
+invaginated. After Blanchard.]
+
+[Illustration: 115. Dipylidium caninum. Immature cysticercoid. After
+Grassi and Rovelli.]
+
+The eggs, scattered among the hairs of the dog or cat, are ingested by
+the insect host and in its body cavity they develop into pyriform
+bodies, about 300µ in length, almost entirely destitute of a bladder,
+but in the immature stage provided with a caudal appendage (fig. 115).
+Within the pear-shaped body (fig. 116) are the invaginated head and
+suckers of the future tapeworm. This larval form is known as a
+cysticercoid, in contradistinction to the bladder-like cysticercus of
+many other cestodes. It is often referred to in literature as
+_Cryptocystis trichodectis_ Villot.
+
+As many as fifty of the cysticercoids have been found in the body cavity
+of a single flea. When the dog takes up an infested flea or louse, by
+biting itself, or when the cat licks them up, the larvæ quickly develop
+into tapeworms, reaching sexual maturity in about twenty days in the
+intestine of their host. Puppies and kittens are quickly infested when
+suckling a flea-infested mother, the developing worms having been found
+in the intestines of puppies not more than five or six days old.
+
+[Illustration: 116. Dipylidium caninum. Cysticercoid. After Villet.]
+
+Infestation of human beings occurs only through accidental ingestion of
+an infested flea. It is natural that such cases should occur largely in
+children, where they may come about in some such way as illustrated in
+the accompanying figures 117 and 118.
+
+_Hymenolepis diminuta_, very commonly living in the intestine of mice
+and rats, is also known to occur in man. Its cysticercoid develops in
+the body cavity of a surprising range of meal-infesting insects. Grassi
+and Rovelli (abstract in Ransom, 1904) found it in the larvæ and adult
+of a moth, _Asopia farinalis_, in the earwig, _Anisolabis annulipes_,
+the Tenebrionid beetles _Akis spinosa_ and _Scaurus striatus_. Grassi
+considers that the lepidopter is the normal intermediate host. The
+insect takes up the eggs scattered by rats and mice. It has been
+experimentally demonstrated that man may develop the tapeworm by
+swallowing infested insects. Natural infection probably occurs by
+ingesting such insects with cereals, or imperfectly cooked foods.
+
+[Illustration: 117. One way in which Dipylidium infection in children
+may occur. After Blanchard.]
+
+_Hymenolepis lanceolata_, a parasite of geese and ducks, has been
+reported once for man. The supposed cysticercoid occurs in various small
+crustaceans of the family Cyclopidæ.
+
+[Illustration: 118. The probable method by which Dipylidium infection
+usually occurs.]
+
+Several other cestode parasites of domestic animals are believed to
+develop their intermediate stage in certain arthropods. Among these may
+be mentioned:
+
+_Choanotænia infundibulformis_, of chickens, developing in the house-fly
+(Grassi and Rovelli);
+
+_Davainea cesticillus_, of chickens, in some lepidopter or coleopter
+(Grassi and Rovelli);
+
+_Hymenolepis anatina_, _H. gracilis_, _H. sinuosa_, _H. coronula_ and
+_Fimbriaria fasciolaris_, all occurring in ducks, have been reported as
+developing in small aquatic crustaceans. In these cases, cysticercoids
+have been found which, on account of superficial characters, have been
+regarded as belonging to the several species, but direct experimental
+evidence is scant.
+
+
+ARTHROPODS AS INTERMEDIATE HOSTS OF NEMATODE WORMS
+
+
+FILARIASIS AND MOSQUITOES--A number of species of Nematode worms
+belonging to the genus _Filaria_, infest man and other vertebrates and
+in the larval condition are to be found in the blood. Such infestation
+is known as _filariasis_. The sexually mature worms are to be found in
+the blood, the lymphatics, the mesentery and subcutaneous connective
+tissue. In the cases best studied it has been found that the larval
+forms are taken up by mosquitoes and undergo a transformation before
+they can attain maturity in man.
+
+The larvæ circulating in the blood are conveniently designated as
+microfilariæ. In this stage they are harmless and only one species,
+_Filaria bancrofti_, appears to be of any great pathological
+significance at any stage.
+
+_Filaria bancrofti_ in its adult state, lives in the lymphatics of man.
+Though often causing no injury it has been clearly established that they
+and their eggs may cause various disorders due to stoppage of the
+lymphatic trunks (fig. 119). Manson lists among other effects, abscess,
+varicose groin glands, lymph scrotum, chyluria, and elephantiasis.
+
+The geographical distribution of this parasite is usually given as
+coextensive with that of elephantiasis, but it is by no means certain
+that it is the only cause of this disease and so actual findings of the
+parasites are necessary. Manson reports that it is "an indigenous
+parasite in almost every country throughout the tropical and subtropical
+world, as far north as Spain in Europe and Charlestown in the United
+States, and as far south as Brisbane in Australia." In some sections,
+fully 50 per cent of the natives are infested. Labredo (1910) found
+17.82 per cent infestation in Havana.
+
+[Illustration: 119. Elephantiasis in Man. From "New Sydenham Society's
+Atlas."]
+
+The larval forms of _Filaria bancrofti_ were first discovered in 1863,
+by Demarquay, in a case of chylous dropsy. They were subsequently noted
+under similar conditions, by several workers, and by Wücherer in the
+urine of twenty-eight cases of tropical chyluria, but in 1872 Lewis
+found that the blood of man was the normal habitat, and gave them the
+name _Filaria sanguinis hominis_. The adult worm was found in 1876 by
+Bancroft, and in 1877, Cobbold gave it the name _Filaria bancrofti_. It
+has since been found repeatedly in various parts of the lymphatic
+system, and its life-history has been the subject of detailed studies by
+Manson (1884), Bancroft (1899), Low (1900), Grassi and Noé (1900), Noé
+(1901) and Fülleborn (1910).
+
+The larvæ as they exist in the circulating blood, exhibit a very active
+wriggling movement, without material progression. They may exist in
+enormous numbers, as many as five or six hundred swarming in a single
+drop of blood. This is the more surprising when we consider that they
+measure about 300µ × 8µ, that is, their width is equal to the diameter
+of the red blood corpuscle of their host and their length over
+thirty-seven times as great.
+
+Their organs are very immature and the structure obscure. When they have
+quieted down somewhat in a preparation it may be seen that at the head
+end there is a six-lipped and very delicate prepuce, enclosing a short
+"fang" which may be suddenly exserted and retracted. Completely
+enclosing the larva is a delicate sheath, which is considerably longer
+than the worm itself. To enter into further details of anatomy is beyond
+the scope of this discussion and readers interested are referred to the
+work of Manson and of Fülleborn.
+
+One of the most surprising features of the habits of these larvæ is the
+periodicity which they exhibit in their occurrence in the peripheral
+blood. If a preparation be made during the day time there may be no
+evidence whatever of filarial infestation, whereas a preparation from
+the same patient taken late in the evening or during the night may be
+literally swarming with the parasites. Manson quotes Mackenzie as having
+brought out the further interesting fact that should a "filarial subject
+be made to sleep during the day and remain awake at night, the
+periodicity is reversed; that is to say, the parasites come into the
+blood during the day and disappear from it during the night." There have
+been numerous attempts to explain this peculiar phenomenon of
+periodicity but in spite of objections which have been raised, the most
+plausible remains that of Manson, who believes that it is an adaptation
+correlated with the life-habits of the liberating agent of the parasite,
+the mosquito.
+
+The next stages in the development of _Filaria nocturna_ occur in
+mosquitoes, a fact suggested almost simultaneously by Bancroft and
+Manson in 1877, and first demonstrated by the latter very soon
+thereafter. The experiments were first carried out with _Culex
+quinquefasciatus_ (= _fatigans_) as a host, but it is now known that a
+number of species of mosquitoes, both anopheline and culicine, may serve
+equally well.
+
+When the blood of an infested individual is sucked up and reaches the
+stomach of such a mosquito, the larvæ, by very active movements, escape
+from their sheaths and within a very few hours actively migrate to the
+body cavity of their new host and settle down primarily in the thoracic
+muscles. There in the course of sixteen to twenty days they undergo a
+metamorphosis of which the more conspicuous features are the formation
+of a mouth, an alimentary canal and a trilobed tail. At the same time
+there is an enormous increase in size, the larvæ which measured .3 mm.
+in the blood becoming 1.5 mm. in length. This developmental period may
+be somewhat shortened in some cases and on the other hand may be
+considerably extended. The controlling factor seems to be the one of
+temperature.
+
+The transformed larvæ then reenter the body cavity and finally the
+majority of them reach the interior of the labium (fig. 120). A few
+enter the legs and antennæ, and the abdomen, but these are wanderers
+which, it is possible, may likewise ultimately reach the labium, where
+they await the opportunity to enter their human host.
+
+It was formerly supposed that when the infested mosquito punctured the
+skin of man, the mature larvæ were injected into the circulation. The
+manner in which this occurred was not obvious, for when the insect feeds
+it inserts only the stylets, the labium itself remaining on the surface
+of the skin. Fülleborn has cleared up the question by showing that at
+this time the filariæ escape and, like the hookworm, actively bore into
+the skin of their new host.
+
+[Illustration: 120. Filaria in the muscles and labium of Culex. After
+Blanchard.]
+
+Once entered, they migrate to the lymphatics and there quickly become
+sexually mature. The full grown females measure 85-90 mm. in length by
+.24-.28 mm. in diameter, while the males are less than half this size,
+being about 40 mm. by .1 mm. Fecundation occurs and the females will be
+found filled with eggs in various stages of development, for they are
+normally viviparous.
+
+_Filaria philippinensis_ is reported by Ashburn and Craig (1907) as a
+common blood filaria in the Philippine Islands. As they describe it, it
+differs from _Filaria bancrofti_ primarily in that it does not exhibit
+periodicity. Its development has been found to occur in _Culex
+quinquefasciatus_, where it undergoes metamorphosis in about fourteen or
+fifteen days. There is doubt as to the species being distinct from
+_bancrofti_.
+
+Several other species occur in man and are thought to be transferred by
+various insects, among which have been mentioned Tabanidæ and
+tsetse-flies, but there is no experimental proof in support of such
+conjectures.
+
+_Filaria immitis_ is a dangerous parasite of the dog, the adult worm
+living in the heart and veins of this animal. It is one of the species
+which has been clearly shown to undergo its development in the mosquito,
+particularly in _Anopheles maculipennis_ and _Aedes calopus_ (=
+Stegomyia). The larval form occurs in the peripheral blood, especially
+at night. When taken up by mosquitoes they differ from _Filaria
+bancrofti_ in that they undergo their development in the Malpighian
+tubules rather than in the thoracic muscles. In about twelve days they
+have completed their growth in the tubules, pierce the distal end, and
+pass to the labium. This species occurs primarily in China and Japan,
+but is also found in Europe and in the United States. It is an
+especially favorable species for studying the transformations in the
+mosquito.
+
+[Illustration: 121. Dracunculus medinensis; female; mouth; embryo. After
+Bastian and Leuckart.]
+
+_Filariæ_ are also commonly found in birds, and in this country this is
+the most available source of laboratory material. We have found them
+locally (Ithaca, N. Y.) in the blood of over sixty per cent of all the
+crows examined, at any season of the year, and have also found them in
+English sparrows.
+
+In the crows, they often occur in enormous numbers, as many as two
+thousand having been found in a single drop of the blood of the most
+heavily infested specimen examined. For study, a small drop of blood
+should be mounted on a clean slide and the coverglass rung with vaseline
+or oil to prevent evaporation. In this way they can be kept for hours.
+
+Permanent preparations may be made by spreading out the blood in a film
+on a perfectly clean slide and staining. This is easiest done by
+touching the fresh drop of blood with the end of a second slide which is
+then held at an angle of about 45° to the first slide and drawn over it
+without pressure. Allow the smear to dry in the air and stain in the
+usual way with hæmatoxylin.
+
+
+OTHER NEMATODE PARASITES OF MAN AND ANIMALS DEVELOPING IN ARTHROPODS
+
+_Dracunculus medinensis_ (fig. 121), the so-called guinea-worm, is a
+nematode parasite of man which is widely distributed in tropical Africa,
+Asia, certain parts of Brazil and is occasionally imported into North
+America.
+
+The female worm is excessively long and slender, measuring nearly three
+feet in length and not more than one-fifteenth of an inch in diameter.
+It is found in the subcutaneous connective tissue and when mature
+usually migrates to some part of the leg. Here it pierces the skin and
+there is formed a small superficial ulcer through which the larvæ reach
+the exterior after bursting the body of the mother.
+
+[Illustration: 122. Cyclops, the intermediate host of Dracunculus.]
+
+Fedtschenko (1879) found that when these larvæ reach the water they
+penetrate the carapace of the little crustacean, _Cyclops_ (fig. 122).
+Here they molt several times and undergo a metamorphosis. Fedtschenko,
+in Turkestan, found that these stages required about five weeks, while
+Manson who confirmed these general results, found that eight or nine
+weeks were required in the cooler climate of England.
+
+Infection of the vertebrate host probably occurs through swallowing
+infested cyclops in drinking water. Fedtschenko was unable to
+demonstrate this experimentally and objection has been raised against
+the theory, but Leiper (1907), and Strassen (1907) succeeded in
+infesting monkeys by feeding them on cyclops containing the larvæ.
+
+_Habronema muscæ_ is a worm which has long been known in its larval
+stage, as a parasite of the house-fly. Carter found them in 33 per cent
+of the house-flies examined in Bombay during July, 1860, and since that
+time they have been shown to be very widely distributed. Italian workers
+reported them in 12 per cent to 30 per cent of the flies examined.
+Hewitt reported finding it rarely in England. In this country it was
+first reported by Leidy who found it in about 20 per cent of the flies
+examined at Philadelphia, Pa. Since then it has been reported by several
+American workers. We have found it at Ithaca, N. Y., but have not made
+sufficient examinations to justify stating percentage. Ransom (1913)
+reports it in thirty-nine out of one hundred and thirty-seven flies, or
+28 per cent.
+
+[Illustration: 123. An Echinorhynchid, showing the spinose retractile
+proboscis.]
+
+[Illustration: 124. June beetle (Lachnosterna).]
+
+[Illustration: Larva]
+
+Until very recently the life-history of this parasite was unknown but
+the thorough work of Ransom (1911, 1913) has shown clearly that the
+adult stage occurs in the stomach of horses. The embryos, produced by
+the parent worms in the stomach of the horse, pass out with the feces
+and enter the bodies of fly larvæ which are developing in the manure. In
+these they reach their final stage of larval development at about the
+time the adult flies emerge from the pupal stage. In the adult fly they
+are commonly found in the head, frequently in the proboscis, but they
+occur also in the thorax and abdomen. Infested flies are accidentally
+swallowed by horses and the parasite completes its development to
+maturity in the stomach of its definitive host.
+
+_Gigantorhynchus hirudinaceus_ (= _Echinorhynchus gigas_) is a common
+parasite of the pig and has been reported as occurring in man. The adult
+female is 20-35 cm. long and 4-9 mm. in diameter. It lacks an alimentary
+canal and is provided with a strongly spined protractile rostrum, by
+means of which it attaches to the intestinal mucosa of its host.
+
+The eggs are scattered with the feces of the host and are taken up by
+certain beetle larvæ. In Europe the usual intermediate hosts are the
+larvæ of the cockchafer, _Melolontha vulgaris_, or of the flower beetle,
+_Cetonia aurata_. Stiles has shown that in the United States the
+intermediate host is the larva of the June bug, _Lachnosterna_ (fig.
+124). It is probable that several of the native species serve in this
+capacity.
+
+A number of other nematode parasites of birds and mammals have been
+reported as developing in arthropods but here, as in the case of the
+cestodes, experimental proof is scant. The cases above cited are the
+better established and will serve as illustrations.
+
+
+
+
+CHAPTER VIII
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA
+
+
+MOSQUITOES AND MALARIA
+
+Under the name of malaria is included a group of morbid symptoms
+formerly supposed to be due to a miasm or bad air, but now known to be
+caused by protozoan parasites of the genus _Plasmodium_, which attack
+the red blood corpuscles. It occurs in paroxysms, each marked by a
+chill, followed by high fever and sweating. The fever is either
+intermittent or remittent.
+
+There are three principal types of the disease, due to different species
+of the parasite. They are:
+
+1. The benign-tertian, caused by _Plasmodium vivax_, which undergoes its
+schizogony or asexual cycle in the blood in forty-eight hours or even
+less. This type of the disease,--characterized by fever every two days,
+is the most wide-spread and common.
+
+2. The quartan fever is due to the presence of _Plasmodium malariæ_,
+which has an asexual cycle of seventy-two hours, and therefore the fever
+recurs every three days. This type is more prevalent in temperate and
+sub-tropical regions, but appears to be rare everywhere.
+
+3. The sub-tertian "æstivo-autumnal," or "pernicious" fever is caused by
+_Plasmodium falciparum_. Schizogony usually occurs in the internal
+organs, particularly in the spleen, instead of in the peripheral
+circulation, as is the case of the tertian and quartan forms. The fever
+produced is of an irregular type and the period of schizogony has not
+been definitely determined. It is claimed by some that the variations
+are due to different species of malignant parasites.
+
+It is one of the most wide-spread of human diseases, occurring in almost
+all parts of the world, except in the polar regions and in waterless
+deserts. It is most prevalent in marshy regions.
+
+So commonplace is malaria that it causes little of the dread inspired by
+most of the epidemic diseases, and yet, as Ross says, it is perhaps the
+most important of human diseases. Figures regarding its ravages are
+astounding. Celli estimated that in Italy it caused an average annual
+mortality of fifteen thousand, representing about two million cases. In
+India alone, according to Ross (1910) "it has been officially estimated
+to cause a mean annual death-rate of five per thousand; that is, to kill
+every year, on the average, one million one hundred and thirty
+thousand." In the United States it is widespread and though being
+restricted as the country develops, it still causes enormous losses.
+During the year 1911, "in Alabama alone there were seventy thousand
+cases and seven hundred and seventy deaths." The weakening effects of
+the disease, the invasion of other diseases due to the attacks of
+malaria, are among the very serious results, but they cannot be
+estimated.
+
+Not only is there direct effect on man, but the disease has been one of
+the greatest factors in retarding the development of certain regions.
+Everywhere pioneers have had to face it, and the most fertile regions
+have, in many instances been those most fully dominated by it. Herrick
+(1903) has presented an interesting study of its effects on the
+development of the southern United States and has shown that some parts,
+which are among the most fertile in the world, are rendered practically
+uninhabitable by the ravages of malaria. Howard (1909) estimates that
+the annual money loss from the disease in the United States is not less
+than $100,000,000.
+
+It was formerly supposed that the disease was due to a miasm, to a
+noxious effluvia, or infectious matter rising in the air from swamps. In
+other words its cause was, as the name indicated "mal aria," and the
+deep seated fear of night air is based largely on the belief that this
+miasm was given off at night. Its production was thought to be favored
+by stirring of the soil, dredging operations and the like.
+
+The idea of some intimate connection between malaria and mosquitoes is
+not a new one. According to Manson, Lancisi noted that in some parts of
+Italy the peasants for centuries have believed that malaria is produced
+by the bite of mosquitoes. Celli states that one not rarely hears from
+such peasants the statement that "In such a place, there is much fever,
+because it is full of mosquitoes." Koch points out that in German East
+Africa the natives call malaria and the mosquito by the same name,
+_Mbù_. The opinion was not lacking support from medical men. Celli
+quotes passages from the writings of the Italian physician, Lancisi,
+which indicate that he favored the view in 1717.
+
+Dr. Josiah Nott is almost universally credited with having supported the
+theory, in 1848, but as we have already pointed out his work has been
+misinterpreted. The statements of Beauperthuy, (1853) were more
+explicit.
+
+The clearest early presentation of the circumstantial evidence in favor
+of the theory of mosquito transmission was that of A. F. A. King, an
+American physician, in 1883. He presented a series of epidemiological
+data and showed "how they may be explicable by the supposition that the
+mosquito is the real source of the disease, rather than the inhalation
+or cutaneous absorption of a marsh vapor." We may well give the space to
+summarizing his argument here for it has been so remarkably
+substantiated by subsequent work:
+
+1. Malaria, like mosquitoes, affects by preference low and moist
+localities, such as swamps, fens, jungles, marshes, etc.
+
+2. Malaria is hardly ever developed at a lower temperature than 60°
+Fahr., and such a temperature is necessary for the development of the
+mosquito.
+
+3. Mosquitoes, like malaria, may both accumulate in and be obstructed by
+forests lying in the course of winds blowing from malarious localities.
+
+4. By atmospheric currents malaria and mosquitoes are alike capable of
+being transported for considerable distances.
+
+5. Malaria may be developed in previously healthy places by turning up
+the soil, as in making excavations for the foundation of houses, tracks
+for railroads, and beds for canals, because these operations afford
+breeding places for mosquitoes.
+
+6. In proportion as countries, previously malarious, are cleared up and
+thickly settled, periodical fevers disappear, because swamps and pools
+are drained so that the mosquito cannot readily find a place suitable to
+deposit her eggs.
+
+7. Malaria is most dangerous when the sun is down and the danger of
+exposure after sunset is greatly increased by the person exposed
+sleeping in the night air. Both facts are readily explicable by the
+mosquito malaria theory.
+
+8. In malarial districts the use of fire, both indoors and to those who
+sleep out, affords a comparative security against malaria, because of
+the destruction of mosquitoes.
+
+9. It is claimed that the air of cities in some way renders the poison
+innocuous, for, though a malarial disease may be raging outside, it does
+not penetrate far into the interior. We may easily conceive that
+mosquitoes, while invading cities during their nocturnal pilgrimages
+will be so far arrested by walls and houses, as well as attracted by
+lights in the suburbs, that many of them will in this way be prevented
+from penetrating "far into the interior."
+
+10. Malarial diseases and likewise mosquitoes are most prevalent toward
+the latter part of summer and in the autumn.
+
+11. Various writers have maintained that malaria is arrested by canvas
+curtains, gauze veils and mosquito nets and have recommended the rise of
+mosquito curtains, "through which malaria can seldom or never pass." It
+can hardly be conceived that these intercept marsh-air but they
+certainly do protect from mosquitoes.
+
+12. Malaria spares no age, but it affects infants much less frequently
+than adults, because young infants are usually carefully housed and
+protected from mosquito inoculation.
+
+Correlated with the miasmatic theory was the belief that some animal or
+vegetable organism which lived in marshes, produced malaria, and
+frequent searches were made for it. Salisbury (1862) thought this
+causative organism to be an alga, of the genus _Palmella_; others
+attributed it to certain fungi or bacteria.
+
+In 1880, the French physician, Laveran, working in Algeria, discovered
+an amoeboid organism in the blood of malarial patients and definitely
+established the parasitic nature of this disease. Pigmented granules had
+been noted by Meckel as long ago as 1847, in the spleen and blood of a
+patient who had died of malaria, and his observations had been
+repeatedly verified, but the granules had been regarded as degeneration
+products, and the fact that they occurred in the body of a foreign
+organism had been overlooked.
+
+Soon after the discovery of the parasites in the blood, Gerhardt (1884)
+succeeded in transferring the disease to healthy individuals by
+inoculation of malarious blood, and thus proved that it is a true
+infection. This was verified by numerous experimenters and it was found
+that inoculation with a very minute quantity of the diseased blood would
+not only produce malaria but the particular type of disease.
+
+Laveran traced out the life cycle of the malarial parasite as it occurs
+in man. The details as we now know them and as they are illustrated by
+the accompanying figure 125, are as follows:
+
+The infecting organism or _sporozoite_, is introduced into the
+circulation, penetrates a red blood corpuscle, and forms the amoeboid
+_schizont_. This lives at the expense of the corpuscle and as it
+develops there are deposited in its body scattered black or reddish
+black particles. These are generally called melanin granules, but are
+much better referred to as hæmozoin, as they are not related to
+melanin. The hæmozoin is the most conspicuous part of the parasite, a
+feature of advantage in diagnosing from unstained preparations.
+
+[Illustration: 125. Life cycle of the malaria parasite. Adapted from
+Leuckart's chart, by Miss Anna Stryke.]
+
+As the schizont matures, its nucleus breaks up into a number of daughter
+nuclei, each with a rounded mass of protoplasm about it, and finally the
+corpuscles are broken down and these rounded bodies are liberated in the
+plasma as _merozoites_. These merozoites infect new corpuscles and thus
+the asexual cycle is continued. The malarial paroxysm is coincident with
+sporulation.
+
+As early as Laveran's time it was known that under conditions not yet
+determined there are to be found in the blood of malarious patients
+another phase of the parasite, differing in form according to the type
+of the disease. In the pernicious type these appear as large,
+crescent-shaped organisms which have commonly been called "crescents."
+We now know that these are sexual forms.
+
+When the parasite became known there immediately arose speculations as
+to the way in which it was transferred from man to man. It was thought
+by some that in nature it occurred as a free-living amoeba, and that
+it gained access to man through being taken up with impure water.
+However, numerous attempts to infect healthy persons by having them
+drink or inhale marsh water, or by injecting it into their circulation
+resulted in failure, and influenced by Leuckart's and Melnikoff's work
+on _Dipylidium_, that of Fedtschenko on _Dracunculus_, and more
+especially by that of Manson on _Filaria_, search was made for some
+insect which might transfer the parasite.
+
+Laveran had early suggested that the rôle of carrier might be played by
+the mosquito, but Manson first clearly formulated the hypothesis, and it
+was largely due to his suggestions that Ross in India, undertook to
+solve the problem. With no knowledge of the form or of the appearance in
+this stage, or of the species of mosquito concerned, Ross spent almost
+two and a half years of the most arduous work in the search and finally
+in August, 1897, seventeen years after the discovery of the parasite in
+man, he obtained his first definite clue. In dissecting a
+"dappled-winged mosquito," "every cell was searched and to my intense
+disappointment nothing whatever was found, until I came to the insect's
+stomach. Here, however, just as I was about to abandon the examination,
+I saw a very delicate circular cell, apparently lying amongst the
+ordinary cells of the organ and scarcely distinguishable from them. On
+looking further, another and another similar object presented itself. I
+now focused the lens carefully on one of these, and found that it
+contained a few minute granules of some black substance, exactly like
+the pigment of the parasite of malaria. I counted altogether twelve of
+these cells in the insect."
+
+Further search showed that "the contents of the mature pigment cells did
+not consist of clear fluid but of a multitude of delicate, thread-like
+bodies which on the rupture of the parent cell, were poured into the
+body cavity of the insect. They were evidently spores."
+
+With these facts established, confirmation and extension of Ross's
+results quickly followed, from many different sources. We cannot trace
+this work in detail but will only point out that much of the credit is
+due to the Italian workers, Grassi, Bignami, and Bastianelli, and to
+Koch and Daniels.
+
+It had already been found that when fresh blood was mounted and properly
+protected against evaporation, a peculiar change occurred in these
+crescents after about half an hour's time. From certain of them there
+were pushed out long whip-like processes which moved with a very active,
+lashing movement. The parasite at this stage is known as the
+"flagellated body." Others, differing somewhat in details of structure,
+become rounded but do not give off "flagella."
+
+The American worker, MacCallum (1897), in studying bird malaria as found
+in crows, first recognized the true nature of these bodies. He regarded
+them as sexual forms and believed that the so-called flagella played the
+part of spermatozoa. Thus, the "flagellated body" is in reality a
+_microgametoblast_, producing _microgametes_, or the male sexual
+element, while the others constitute the _macrogametes_, or female
+elements.
+
+It was found that when blood containing these sexual forms was sucked up
+by an Anopheline mosquito and taken into its stomach, a microgamete
+penetrated and fertilized a macrogamete in a way analogous to what takes
+place in the fertilization of the egg in higher forms. The resultant,
+mobile organism is known as the _migratory ookinete_. In this stage the
+parasite bores through the epithelial lining of the "stomach"
+(mid-intestine) of the mosquito and becomes encysted under the muscle
+layers. Here the _oocyst_, as it is now known, matures and breaks up
+into the body cavity and finally its products come to lie in the
+salivary glands of the mosquito. Ten to twelve days are required for
+these changes, after which the mosquito is infective, capable of
+introducing the parasite with its saliva, when feeding upon a healthy
+person.
+
+Thus the malarial parasite is known to have a double cycle, an
+alternation of generations, of which the asexual stage is undergone in
+man, the sexual in certain species of mosquitoes. The mosquito is
+therefore the definitive host rather than the _intermediate_, as usually
+stated.
+
+The complicated cycle may be made clearer by the diagram of Miss Stryke
+(1912) which, by means of a double-headed mosquito (fig. 126) endeavors
+to show how infection takes place through the biting of the human
+victim, (at A), in whom asexual multiplication then takes place, and how
+the sexual stages, taken up at B in the diagram, are passed in the body
+of the mosquito.
+
+[Illustration: 126. Life cycle of the malarial parasite. After Miss Anna
+Stryke.]
+
+The experimental proof that mosquitoes of the Anopheline group are
+necessary agents in the transmission of malaria was afforded in 1900
+when two English physicians, Drs. Sambon and Low lived for the three
+most malarial months in the midst of the Roman Campagna, a region
+famous for centuries as a hot-bed of malaria. The two experimenters
+moved about freely throughout the day, exposed themselves to rains and
+all kinds of weather, drank marsh water, slept exposed to the marsh air,
+and, in short, did everything which was supposed to cause malaria,
+except that they protected themselves thoroughly from mosquito bites,
+retiring at sunset to a mosquito-proof hut. Though they took no quinine
+and all of their neighbors suffered from malaria, they were absolutely
+free from the disease.
+
+To complete the proof, mosquitoes which had fed in Rome on malarious
+patients were sent to England and allowed to bite two volunteers, one of
+them Dr. Manson's own son, who had not been otherwise exposed to the
+disease. Both of these gentlemen contracted typical cases of malaria and
+the parasites were to be found in abundance in their blood.
+
+[Illustration: 127. Eggs of Anopheles. After Howard.]
+
+Since that time there have been many practical demonstrations of the
+fact that malaria is transmitted exclusively by the bite of mosquitoes
+and that the destruction of the mosquitoes means the elimination of the
+disease.
+
+We have said that the malarial parasite is able to undergo its
+development only in certain species of mosquitoes belonging to the
+Anopheline group. It is by no means certain that all of this group even,
+are capable of acting as the definitive host of the parasites, and much
+careful experiment work is still needed along this line. In the United
+States, several species have been found to be implicated, _Anopheles
+quadrimaculatus_ and _Anopheles crucians_ being the most common. The
+characteristics of these species and the distinctions between them and
+other mosquitoes will be discussed in Chapter XII.
+
+In antimalarial work it is desirable to distinguish the anopheline
+mosquitoes from the culicine species in all stages. The following
+tabulation presents the more striking distinctions between the groups as
+represented in the United States.
+
+_Anopheles_                             _Culex, Aedes, etc_.
+
+_Eggs_: Laid singly in small            Deposited in clumps in the
+numbers upon the surface of the         form of a raft (Culex group) or
+water. Eggs lie upon their sides        deposited singly in the water or
+and float by means of lateral           on the ground in places which
+expansions (fig. 127).                  may later be submerged.
+
+_Larva_: When at rest floats in         When at rest (with few exceptions)
+a horizontal position beneath the       floats suspended in an
+surface film. No respiratory            oblique or vertical position, or
+tube but instead a flattened            more rarely nearly horizontal,
+area on the eighth abdominal            with the respiratory tube in
+segment into which the two              contact with the surface film
+spiracles open (fig. 128).              (fig. 128).
+
+_Adults_: Palpi in both sexes           Palpi short in the female, in
+nearly or quite as long as the          the male usually elongate.
+proboscis. Proboscis projecting         Proboscis projects forward at an
+forward nearly on line with the         angle with the axis of the body.
+axis of the body. When at rest          When at rest on a vertical wall
+on a vertical wall the body is          the body is usually held parallel
+usually held at an angle with the       or the tip of the abdomen inclined
+vertical (fig. 128). Wings frequently   towards the wall (fig. 128).
+spotted (fig. 130).                     Wings usually not spotted.
+
+[Illustration: 128. (_a_) Normal position of the larvæ of Culex and
+Anopheles in the water. Culex, left; Anopheles, middle; Culex pupa,
+right hand figure.]
+
+These malarial-bearing species are essentially domesticated mosquitoes.
+They develop in any accumulation of water which stands for a week or
+more. Ponds, puddles, rain barrels, horse troughs, cess-pools, cans,
+even the foot-prints of animals in marshy ground may afford them
+breeding places.
+
+[Illustration: 128. (_b_) Normal position of Culex and Anopheles on the
+wall.]
+
+It is clear from what has been said regarding the life cycle of the
+malarial parasite that the mosquito is harmless if not itself diseased.
+Hence malarial-bearing species may abound in the neighborhood where
+there is no malaria, the disease being absent simply because the
+mosquitoes are uninfected. Such a locality is potentially malarious and
+needs only the introduction of a malarial patient who is exposed to the
+mosquitoes. It is found that such patients may harbor the parasites in
+their blood long after they are apparently well and thus may serve as a
+menace, just as do the so-called typhoid carriers. In some malarious
+regions as high as 80-90 per cent of the natives are such
+malaria-carriers and must be reckoned with in antimalaria measures.
+
+Based upon our present day knowledge of the life cycle of the malarial
+parasite the fight against the disease becomes primarily a problem in
+economic entomology,--it is a question of insect control, in its
+broadest interpretation.
+
+[Illustration: 129. Larva of Anopheles. After Howard.]
+
+The lines of defence and offence against the disease as outlined by
+Boyce (1909) are:
+
+  1. Measures to avoid the reservoir (man):
+
+    Segregation.
+
+    Screening of patients.
+
+  2. Measures to avoid Anopheles:
+
+    Choice of suitable locality, when possible.
+
+    Screening of houses and porches.
+
+    Sleeping under mosquito nets.
+
+  3. Measures to exterminate the Anopheles:
+
+    Use of natural enemies.
+
+    Use of culicides, oiling ponds, etc.
+
+    Drainage and scavenging to destroy breeding places.
+
+    Enforcement of penalties for harboring larvæ or keeping stagnant
+      water.
+
+    Educational methods.
+
+  4. Systematic treatment with quinine to exterminate the parasites.
+
+
+MOSQUITOES AND YELLOW FEVER
+
+Yellow fever was until recently one of the most dreaded of epidemic
+diseases. It is an acute, specific and infectious disease,
+non-contagious in character but occurring in epidemics, or endemics,
+within a peculiarly limited geographical area. It is highly fatal, but
+those who recover are generally immune from subsequent attacks.
+
+It is generally regarded as an American disease, having been found by
+Cortez, in Mexico, and being confined principally to the American
+continents and islands. It also occurs in Africa and attempts have been
+made to show that it was originally an African disease but there is not
+sufficient evidence to establish this view.
+
+There have been many noted outbreaks in the United States. Boston
+suffered from it in 1691 and again in 1693; New York in 1668 and as late
+as 1856; Baltimore in 1819. In 1793 occurred the great epidemic in
+Philadelphia, with a death rate of one in ten of the population. In the
+past century it was present almost every year in some locality of our
+Southern States, New Orleans being the greatest sufferer. In the latter
+city there were 7848 deaths from the disease in 1853, 4854 in 1858, and
+4046 in 1878. The last notable outbreak was in 1905. Reed and Carroll
+(1901) estimated that during the period from 1793 to 1900 there had not
+been less than 500,000 cases in the United States.
+
+[Illustration: 130. Anopheles quadrimaculatus, male and female,
+(×3½). After Howard.]
+
+As in the case of the plague, the most stringent methods of control
+proved ineffective and helplessness, almost hopelessness marked the
+great epidemics. A vivid picture of conditions is that given by Mathew
+Cary, 1793 (quoted by Kelly, 1906) in "A Short Account of the Malignant
+Fever Lately Prevalent in Philadelphia."
+
+[Illustration: 131. Anopheles punctipennis. Female, (×4). After Howard.]
+
+"The consternation of the people of Philadelphia at this period was
+carried beyond all bounds. Dismay and affright were visible in the
+countenance of almost every person. Of those who remained, many shut
+themselves in their houses and were afraid to walk the streets. * * *
+The corpses of the most respectable citizens, even those who did not die
+of the epidemic, were carried to the grave on the shafts of a chair
+(chaise), the horse driven by a negro, unattended by friends or
+relative, and without any sort of ceremony. People hastily shifted their
+course at the sight of a hearse coming toward them. Many never walked on
+the footpath, but went into the middle of the streets to avoid being
+infected by passing by houses wherein people had died. Acquaintances and
+friends avoided each other in the streets and only signified their
+regard by a cold nod. The old custom of shaking hands fell into such
+disuse that many shrunk back with affright at even the offer of the
+hand. A person with a crape, or any appearance of mourning was shunned
+like a viper. And many valued themselves highly on the skill and address
+with which they got to the windward of every person they met. Indeed, it
+is not probable that London, at the last stage of the plague, exhibited
+stronger marks of terror than were to be seen in Philadelphia from the
+24th or 25th of August until pretty late in September."
+
+[Illustration: 132. Anopheles crucians. Female (×4). After Howard.]
+
+Such was the condition in Philadelphia in 1793 and, as far as methods of
+control of the disease were concerned, there was practically no advance
+during the last century. The dominant theory was that yellow fever was
+spread by _fomites_, that is, exposed bedding, clothing, baggage, and
+the like. As late as 1898 a bulletin of the United States Marine
+Hospital Service stated:
+
+"While yellow fever is a communicable disease, it is not contagious in
+the ordinary acceptance of the term, but is spread by the infection of
+places and articles of bedding, clothing, and furniture."
+
+Based upon this theory, houses, baggage, freight, even mail, were
+disinfected, and the most rigid quarantine regulations were enforced.
+The hardships to which people of the stricken regions were subjected and
+the financial losses are incalculable. And withal, the only efficient
+check upon the disease seemed to be the heavy frosts. It was found that
+for some reason, the epidemic abated with cold weather,--a measure
+beyond human control.
+
+[Illustration: 133. Culex sollicitans. Female (×4). After Howard.]
+
+It is not strange that among the multitude of theories advanced to
+explain the cause and method of dissemination of the disease there
+should be suggestions that yellow fever was transmitted by the mosquito.
+We have seen that Beauperthuy (1855) clearly urged this theory.
+
+More detailed, and of the greatest influence in the final solution of
+the problem were the arguments of Dr. Cárlos Finlay, of Havana. In 1881,
+in a paper presented before the "Real Academia de Ciencias Médicas,
+Físicas y Naturales de la Habana," he said:
+
+"I feel convinced that any theory which attributes the origin and the
+propagation of yellow fever to atmospheric influences, to miasmatic or
+meteorological conditions, to filth, or to the neglect of general
+hygienic precautions, must be considered as utterly indefensible."
+
+He postulated the existence of a material transportable substance
+causing yellow fever,--"something tangible which requires to be conveyed
+from the sick to the healthy before the disease can be propagated" and
+after discussing the peculiarities of the spread of the disease and the
+influence of meteorological conditions, he decides that the carriers of
+the disease must be sought among insects. He continues:
+
+"On the other hand, the fact of yellow fever being characterized both
+clinically and (according to recent findings) histologically, by lesions
+of the blood vessels and by alterations of the physical and chemical
+conditions of the blood, suggested that the insect which should convey
+the infectious particles from the patient to the healthy should be
+looked for among those which drive their sting into blood vessels in
+order to suck human blood. Finally, by reason of other considerations
+which need not be stated here, I came to think that the mosquito might
+be the transmitter of yellow fever."
+
+"Assimilating the disease to small-pox and to vaccination, it occurred
+to me that in order to inoculate yellow fever it would be necessary to
+pick out the inoculable material from within the blood vessels of a
+yellow fever patient and to carry it likewise into the interior of a
+blood vessel of a person who was to be inoculated. All of which
+conditions the mosquito satisfies most admirably through its bite."
+
+In the course of his study of the problem, Finlay made detailed studies
+of the life history and habits of the common mosquitoes at Havana, and
+arrived at the conclusion that the carrier of the yellow fever was the
+_Culex mosquito_ or _Aëdes calopus_, as it is now known. With this
+species he undertook direct experimental tests, and believed that he
+succeeded in transmitting the disease by the bite of infected mosquitoes
+in three cases. Unfortunately, possibility of other exposure was not
+absolutely excluded, and the experiments attracted little attention.
+
+Throughout the next twenty years Finlay continued his work on yellow
+fever, modifying his original theory somewhat as time went on. Among his
+later suggestions was that in the light of Smith's work on Texas fever,
+his theory must be "somewhat modified so as to include the important
+circumstance that the faculty of transmitting the yellow fever germ need
+not be limited to the parent insect, directly contaminated by stinging a
+yellow fever patient (or perhaps by contact with or feeding from his
+discharges), but may be likewise inherited by the next generation of
+mosquitoes issued from the contaminated parent." He believed that the
+bite of a single mosquito produced a light attack of the disease and was
+thus effective in immunizing the patient. Throughout the period, many
+apparently successful attempts to transmit the disease by mosquitoes
+were made. In the light of present day knowledge we must regard these as
+defective not only because possibility of other infection was not
+absolutely excluded but because no account was taken of the incubation
+period within the body of the mosquito.
+
+In 1900, while the American army was stationed in Cuba there occurred an
+epidemic of yellow fever and an army medical board was appointed for
+"the purpose of pursuing scientific investigations with reference to the
+acute infectious diseases prevalent on the island." This was headed by
+Walter Reed and associated with him were James Carroll, Jesse W. Lazear
+and Aristides Agramonte, the latter a Cuban immune. For a detailed
+summary of this work the lay reader cannot do better than read Dr.
+Kelly's fascinating biography "Walter Reed and Yellow Fever."
+
+Arriving at the army barracks near Havana the Commission first took up
+the study of _Bacillus icteroides_, the organism which Sanarelli, an
+Italian physician, had declared the causative agent in yellow fever.
+They were unable to isolate this bacillus either from the blood during
+life or from the blood and organs of cadavers and therefore turned their
+attention to Finlay's theory of the propagation of yellow fever by means
+of the mosquito. In this work they had the unselfish and enthusiastic
+support of Dr. Finlay himself, who not only consulted with them and
+placed his publications at their disposal, but furnished eggs from which
+their experimental mosquitoes were obtained. Inoculations of eleven
+non-immunes through the bite of infected mosquitoes were made, and of
+these, two gave positive results. The first of the two was Dr. Carroll
+who allowed himself to be bitten by a mosquito which had been caused to
+feed upon four cases of yellow fever, two of them severe and two mild.
+The first patient had been bitten twelve days before.
+
+Three days after being bitten, Dr. Carroll came down with a typical case
+of yellow fever. So severe was the attack that for three days his life
+hung in the balance. During his convalescence an incident occurred which
+showed how the theory of mosquito transmission of the disease was
+generally regarded. We quote from Dr. Kelly: "One of his nurses who came
+from Tennessee had had considerable experience with yellow fever, having
+indeed, lost her husband and several children from it. One day early in
+his illness Dr. Carroll mentioned to her that he had contracted the
+disease through the bite of a mosquito, and noticed that she looked
+surprised. Some time later, when well enough to look over the daily
+records of his condition, he found this entry: 'Says he got his illness
+through the bite of a mosquito,--delirious'."
+
+The second case was that of an American who was bitten by four
+mosquitoes, two of which had bitten severe (fatal) cases of yellow fever
+twelve days previously, one of which had bitten a severe case (second
+day) sixteen days before and one which had bitten a severe case eight
+days before. Five days later, the subject developed a well pronounced
+but mild case of the disease.
+
+In the meantime, another member of the Commission, Dr. Lazear, was
+accidentally bitten by a mosquito while collecting blood from yellow
+fever patients. Five days later he contracted a typical case which
+resulted fatally.
+
+So clear was the evidence from these preliminary experiments that the
+commission felt warranted in announcing, October 27, 1900, that, "The
+mosquito serves as the intermediate host for the parasite of yellow
+fever, and it is highly probable that the disease is only propagated
+through the bite of this insect."
+
+In order to extend the experimental evidence under conditions which
+could leave no possibility of infection from other sources, a special
+experimental sanitary station, named in honor of the deceased member of
+the Commission, was established in an open field near the town of
+Quemados, Cuba. Here there were constructed two small buildings known
+respectively as the "infected clothing building" and the "infected
+mosquito building."
+
+The infected clothing building, 14 × 20 feet in size, was purposely so
+constructed as to exclude anything like efficient ventilation, but was
+thoroughly screened to prevent the entrance of mosquitoes. Into this
+building were brought sheets, pillow-slips, blankets, etc., contaminated
+by contact with cases of yellow fever and their discharges,--many of
+them purposely soiled with a liberal quantity of black vomit, urine, and
+fecal matter from patients sick with yellow fever. Nothing could better
+serve as the fomites which were supposed to convey the dread disease.
+
+Three non-immunes unpacked these articles, giving each a thorough
+handling and shaking in order to disseminate through the air of the room
+the specific agent of the disease. They were then used in making up the
+beds which the volunteers occupied each night for a period of twenty
+days. The experiment was repeated three times, volunteers even sleeping
+in the soiled garments of yellow fever victims but in not a single case
+was there the slightest symptom of disease. The theory of the spread of
+yellow fever by fomites was completely demolished.
+
+The infected mosquito building, equal in size to its companion, was the
+antithesis as far as other features were concerned. It was so
+constructed as to give the best possible ventilation, and bedding which
+was brought into it was thoroughly sterilized. Like the infected
+clothing building it was carefully screened, but in this case it was in
+order to keep mosquitoes in it as well as to prevent entrance of others.
+Through the middle of the room ran a mosquito-proof screen.
+
+On December 5, 1900, a non-immune volunteer who had been in the
+quarantine camp for fifteen days and had had no other possible exposure,
+allowed himself to be bitten by five mosquitoes which had fed on yellow
+fever patients fifteen or more days previously. The results were fully
+confirmatory of the earlier experiments of the Commission--at the end of
+three days, nine and a half hours, the subject came down with a well
+marked case of yellow fever.
+
+In all, ten cases of experimental yellow fever, caused by the bite of
+infected mosquitoes were developed in Camp Lazear. Throughout the period
+of the disease, other non-immunes slept in the little building,
+separated from the patient only by the mosquito-proof screen, but in no
+circumstances did they suffer any ill effects.
+
+It was found that a yellow fever patient was capable of infecting
+mosquitoes only during the first three or four days after coming down
+with the disease. Moreover, after the mosquito has bitten such a
+patient, a period of at least twelve days must elapse before the insect
+is capable of transmitting the disease.
+
+Once the organism has undergone its twelve day development, the mosquito
+may remain infective for weeks. In experiments of the Commission, two of
+the mosquitoes transmitted the disease to a volunteer fifty-seven days
+after their contamination. No other volunteers presenting themselves,
+one of these mosquitoes died the sixty-ninth and one the seventy-first
+day after their original contamination, without it being determined
+whether they were still capable of transmitting the disease.
+
+So carefully carried out was this work and so conclusive were the
+results that Dr. Reed was justified in writing:
+
+"Six months ago, when we landed on this island, absolutely nothing was
+known concerning the propagation and spread of yellow fever--it was all
+an unfathomable mystery--but today the curtain has been drawn--its mode
+of propagation is established and we know that a case minus mosquitoes
+is no more dangerous than one of chills and fever."
+
+The conclusions of the Commission were fully substantiated by numerous
+workers, notably Dr. Guiteras of the Havana Board of Health, who had
+taken a lively interest in the work and whose results were made known in
+1901, and by the Brazilian and French Commission at Sao Paulo, Brazil,
+in 1903.
+
+Throughout the work of the Army Commission and down to the present time
+many fruitless efforts have been made to discover the specific organism
+of yellow fever. It was clearly established that the claims of Sanarelli
+for _Bacillus icteroides_ were without foundation. It was found, too,
+that whatever the infective agent might be it was capable of passing
+through a Berkefeld filter and thus belongs to the puzzling group of
+"filterable viruses." It was further found that the virus was destroyed
+by heating up to 55° C for ten minutes. It is generally believed that
+the organism is a Protozoan.
+
+The question of the hereditary transmission of the yellow fever organism
+within the mosquito was left unsettled by the Army Commission, though,
+as we have seen, it was raised by Finlay. Marchoux and Simond, of the
+French Commission devoted much attention to this phase of the problem
+and basing their conclusions on one apparently positive case, they
+decided that the disease could be transmitted through the egg of an
+infected _Aëdes calopus_ to the second generation and thence to man. The
+conclusion, which is of very great importance in the control of yellow
+fever, has not been verified by other workers.
+
+Once clearly established that yellow fever was transmitted solely by
+mosquitoes, the question of the characteristics, habits, and
+geographical distribution of the insect carrier became of vital
+importance.
+
+_Aëdes calopus_, more commonly known as _Stegomyia fasciata_ or
+_Stegomyia calopus_ (fig. 134) is a moderate sized, rather strikingly
+marked mosquito. The general color is dark-brown or reddish-brown, but
+the thorax has a conspicuous broad, silvery-white curved line on each
+side, with two parallel median silvery lines. Between the latter there
+is a slender, broken line. The whole gives a lyre-shaped pattern to the
+thorax. The abdomen is dark with silvery-white basal bands and silvery
+white spots on each side of the abdominal segments. Legs black with
+rings of pure white at the base of the segments.
+
+Size of the female 3.3 to 5 mm.; male 3 to 4.5 mm.
+
+[Illustration: 134. The yellow fever mosquito (Aëdes calopus). (×7).
+After Howard.]
+
+It is preeminently a domesticated species, being found almost
+exclusively about the habitation of man. "Its long association with man
+is shown by many of its habits. It approaches stealthily from behind. It
+retreats upon the slightest alarm. The ankles and, when one is sitting
+at a table or desk, the underside of the hands and wrists are favorable
+points of attack. It attacks silently, whereas other mosquitoes have a
+piping or humming note. The warning sound has doubtless been suppressed
+in the evolutionary process of its adaptation to man. It is extremely
+wary. It hides whenever it can, concealing itself in garments, working
+into the pockets, and under the lapels of coats, and crawling up under
+the clothes to bite the legs. In houses, it will hide in dark corners,
+under picture moldings and behind the heads of old-fashioned bedsteads.
+It will enter closets and hide in the folds of garments."--Howard.
+
+It was claimed by the French Commission, and subsequently often stated
+in discussions of the relation of the mosquito to yellow fever that the
+mature _Aëdes calopus_ will bite only at night. If this were true it
+would be of the greatest importance in measures to avoid the disease.
+Unfortunately, the claim was illy founded and numerous workers have
+clearly established that the exact converse is more nearly true, this
+mosquito being pre-eminently a day species, feeding most actively in
+early morning, about sunrise, and late in the afternoon. On cloudy days
+it attacks at any time during the day. Thus there is peril in the
+doctrine that infected regions may be visited with perfect safety during
+the daytime and that measures to avoid the mosquito attack need be taken
+only at night.
+
+[Illustration: 135_a_. Aëdes calopus. Pupa. After Howard.]
+
+Dr. Finlay maintained that the adult, even when starved, would not bite
+when the temperature was below 23° C, but subsequent studies have shown
+that this statement needs modification. The French Commission, working
+at Rio de Janeiro, found that _Aëdes calopus_ would bite regularly at
+temperatures between 22° and 25° and that the optimum temperature was
+between 27° and 30° C, but their experiments led them to believe that it
+would bite in nature at a temperature as low as 17° C.
+
+The yellow fever mosquito breeds in cisterns, water barrels, pitchers
+and in the various water receptacles about the house. In our own
+Southern States it very commonly breeds in the above-ground cisterns
+which are in general use. Often the larvæ (fig. 135b) are found in
+flower vases, or even in the little cups of water which are placed under
+the legs of tables to prevent their being overrun by ants. They have
+been repeatedly found breeding in the holy water font in churches. In
+short, they breed in any collection of water in close proximity to the
+dwellings or gathering places of man.
+
+The life cycle under favorable conditions is completed in from twelve to
+fifteen days. These figures are of course very dependent upon the
+temperature. The Army Commission in Cuba found that the cycle might be
+completed in as brief a period as nine and a half days. Under less
+favorable conditions it may be greatly lengthened.
+
+The adults are long lived. We have seen that during the experimental
+work in Cuba specimens were kept in captivity for sixty-nine and
+seventy-one days, respectively, and that they were proved to retain
+their infectivity for at least fifty-seven days. Dr. Guiteras
+subsequently kept an infected adult for one hundred and fifty-four days.
+
+Low temperatures have a very great effect not only on development, but
+on the activity and even life of the adults. Long before the method of
+transmission of yellow fever was discovered it was well known that the
+epidemics were brought to a close by heavy frosts, and it is now known
+that this is due to the killing of the mosquitoes which alone could
+spread the disease.
+
+[Illustration: 135_b_. Aëdes calopus; larva. (×7). After Howard.]
+
+_Aëdes calopus_ has a very wide distribution since, as Howard says,
+being a domestic mosquito, having a fairly long life in the adult stage,
+and having the custom of hiding itself in the most ingenious ways, it is
+particularly subject to carriage for long distances on board vessels, in
+railway trains, even packed in baggage. In general, its permanent
+distribution is from 40 degrees north latitude to 40 degrees south
+latitude (Brumpt), in a belt extending around the world. In the United
+States it breeds in most of our Southern States.
+
+Thus, as in the case of malaria, there are many places where the insect
+carrier is abundant but where yellow fever does not occur. Such, for
+instance, are Hawaii, Australia and Asia. An outbreak may occur at any
+time that a patient suffering from the disease is allowed to enter and
+become a source of infection for the mosquitoes. In this connection
+various writers have called attention to the menace from the Panama
+Canal. When it is completed, it will allow of direct passage from
+regions where yellow fever is endemic and this will greatly increase the
+possibility of its introduction into these places where it is now
+unknown. The result, with a wholly non-immune population, would be
+appalling.
+
+On the other hand, there are places wholly outside of the normal range
+of _Aëdes calopus_ where the disease has raged. Such are New York,
+Boston, and even Philadelphia, which have suffered notable epidemics.
+These outbreaks have been due to the introduction of infected mosquitoes
+during the heat of summer, when they have not only conveyed the disease
+but have found conditions favorable for their multiplication. Or,
+uninfected mosquitoes have been thus accidentally brought in and
+developed in large numbers, needing then only the accidental
+introduction of cases of the disease to start an epidemic.
+
+Methods of control of various diseases have been revolutionized by the
+discovery that they were insect-borne, but in no other case has the
+change been as radical or the results as spectacular as in the case of
+yellow fever. The "shot-gun quarantine," the sufferings and horrors, the
+hopelessness of fighting absolutely blindly have given way to an
+efficient, clear-cut method of control, based upon the knowledge that
+the disease is carried from man to man solely by the mosquito, _Aëdes
+calopus_. The lines of defense and offense are essentially as follows:
+
+In the first place, when a case of yellow fever occurs, stringent
+precautions must be adopted to prevent the infection of mosquitoes and
+the escape of any already infected. This means that the patient must be
+removed to a mosquito-proof room, or ward beyond reach of the insects,
+and that the infected room must be thoroughly fumigated at once, to kill
+the mosquitoes hiding within it. All cracks and openings should be
+closed with strips of paper and fumigation with burning sulphur or
+pyrethrum carefully carried out.
+
+It should be remembered that if the first case noted is that of a
+resident rather than imported, it means that the mosquito carriers
+became infected more than two weeks before the case was diagnosed, for
+as we have seen, the germ must undergo a twelve-day period of
+development within its insect host. Therefore a careful search must be
+made for mild cases which, though unrecognized, may serve as foci for
+the spread of the disease.
+
+In face of a threatened epidemic one of the most essential measures is
+to educate the citizens and to gain their complete coöperation in the
+fight along modern lines. This may be done through the schools, the
+pulpit, places of amusement, newspapers and even bulletin boards.
+
+Emphasis should be placed on the necessity of both non-immunes and
+immunes using mosquito curtains, and in all possible ways avoiding
+exposure to the mosquitoes.
+
+Then the backbone of the fight must be the anti-mosquito measures. In
+general, these involve screening and fumigating against adults, and
+control of water supply, oiling, and drainage against the larvæ. The
+region involved must be districted and a thorough survey undertaken to
+locate breeding places, which must, if possible, be eradicated. If they
+are necessary for water supplies, such as casks, or cisterns, they
+should be carefully screened to prevent access of egg-laying adults.
+
+The practical results of anti-mosquito measures in the fight against
+yellow fever are well illustrated by the classic examples of the work in
+Havana, immediately following the discoveries of the Army Commission and
+by the stamping out of the New Orleans epidemic in 1905.
+
+The opportunities for an immediate practical application of the theories
+of the Army Commission in Havana were ideal. The city had always been a
+hotbed of yellow fever and was the principal source from which the
+disease was introduced year after year into our Southern States. It was
+under martial law and with a military governor who was himself a
+physician and thoroughly in sympathy with the views of the Commission,
+the rigid enforcement of the necessary regulations was possible. The
+story of the first campaign has been often told, but nowhere more
+clearly than in Dr. Reed's own account, published in the _Journal of
+Hygiene_ for 1902.
+
+Closer home was the demonstration of the efficacy of these measures in
+controlling the yellow fever outbreak in New Orleans in 1905. During the
+spring and early summer of the year the disease had, unperceived, gained
+a firm foothold in that city and when, in early July the local Board of
+Health took cognizance of its existence, it was estimated that there had
+been in the neighborhood of one hundred cases.
+
+Conditions were not as favorable as they had been under martial law in
+Havana for carrying on a rigid fight along anti-mosquito lines. The
+densely populated city was unprepared, the public had to be educated,
+and an efficient organization built up. The local authorities actively
+began a general fight against the mosquito but in spite of their best
+efforts the disease continued to spread. It was recognized that more
+rigid organization was needed and on August 12th the United States
+Public Health and Marine Hospital Service was put in absolute charge of
+the fight. Up to this time there had been one hundred and forty-two
+deaths from a total of nine hundred and thirteen cases and all of the
+conditions seemed to threaten an outbreak to exceed the memorable one of
+1878 when, as we have seen there were four thousand and forty-six
+deaths.
+
+With the hearty coöperation of the citizens,--physicians and laymen
+alike,--the fight was waged and long before frost or any near approach
+thereto the disease was stamped out,--a thing unheard of in previous
+epidemics. The total loss of life was four hundred and sixty--about 11
+per cent as great as that from the comparable epidemic of 1878. If the
+disease had been promptly recognized and combated with the energy which
+marked the fight later in the summer, the outbreak would have made
+little headway and the great proportion of these lives would have been
+saved.
+
+
+
+
+CHAPTER IX
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA (Continued)
+
+
+INSECTS AND TRYPANOSOMIASES
+
+By trypanosomiasis is meant a condition of animal parasitism, common to
+man and the lower animals, in which trypanosomes, peculiar flagellate
+protozoa, infest the blood. Depending upon the species, they may be
+harmless, producing no appreciable ill-effect, or pathogenic, giving
+rise to conditions of disease. A number of these are known to be
+transferred by insects.
+
+In order that we may consider more fully the developmental stage of
+these parasites within their insect host, it is necessary that we
+describe briefly the structure of the blood-inhabiting stage.
+
+[Illustration: 136. Trypanosoma brucei. After Bruce.]
+
+The trypanosomes are elongated, usually pointed, flagellated protozoa
+(fig. 136) in which the single flagellum, bent under the body, forms the
+outer limit of a delicate undulating membrane. It arises near one end of
+the organism from a minute centrosome-like body which is known as the
+blepheroplast, and at the opposite end extends for a greater or less
+distance as a free flagellum. Enclosing, or close beside the
+blepheroplast is the small kinetonucleus. The principal nucleus, round
+or oval in form, is situated near the center of the body. Asexual
+reproductions occurs in this stage, by longitudinal fission, the nucleus
+and the blepheroplast dividing independently of one another. From the
+blepheroplast of one of the daughter cells a new flagellum is formed.
+
+Among the pathogenic species are to be found the causative organisms of
+some of the most serious diseases of domestic animals and even of man.
+It is probable that these pathogenic species secrete a specific poison.
+The majority of them are tropical in distribution.
+
+Though we are concerned especially with the species which infest man, we
+shall first consider two of the trypanosomes of lower animals, known
+long before any of those of man had been found.
+
+
+FLEAS AND LICE AS CARRIERS OF TRYPANOSOMA LEWISI.--_Trypanosoma lewisi_,
+the first mammalian trypanosome known, is to be found in the blood of
+wild rats. Like its host, it appears to be cosmopolitan in distribution,
+having been reported from several localities in the United States,
+Brazil, Argentine, England, Germany, France, Italy, Russia, Asia and
+Africa.
+
+This species is usually regarded as non-pathogenic, but in experimental
+work, especially with white rats, heavy infestations often result
+fatally, and naturally infested specimens sometimes show evidence of
+injury. Rats which have been infested exhibit at least temporary
+immunity against new infection.
+
+_Trypanosoma lewisi_ is transmitted from rat to rat by fleas and by
+lice. Rabinowitsch and Kempner (1899) first found that healthy rats
+which were kept with infested rats, showed trypanosomes in their blood
+after about two weeks. They found the trypanosomes in the alimentary
+canal of fleas which had fed on the diseased rats. On teasing such fleas
+in physiological salt solution and inoculating them into fresh rats they
+were able to produce the infection. Finally, they showed that the fleas
+which had fed upon infested rats were able to carry the parasites to
+healthy rats. Corresponding experiments with lice were not successful.
+Prowazek (1905) found in the rat louse (_Hæmatopinus spinulosus_)
+organisms which he regarded as developmental stages of the _Trypanosoma
+lewisi_. He believed that the sexual cycle was undergone in this insect.
+
+Nuttall (1908) readily transmitted the trypanosomes through the agency
+of fleas, (_Ceratophyllus fasciatus_ and _Ctenopthalmus agyrtes_). He
+believes that these insects are probably the chief transmitters of the
+parasite. He was also able to transmit it from diseased to healthy rats
+through the agency of the rat louse. He was unable to trace any
+developmental stages in the louse and inclined to the opinion that
+Prowazek was deceived by the presence of extraneous flagellates such as
+are known to exist in a number of blood-sucking arthropods.
+
+Nuttall concludes that since three distinct kinds of blood-sucking
+insects are capable of transmitting _Trypanosoma lewisi_ it appears
+doubtful that this flagellate is a parasite of the invertebrate "host"
+in the sense claimed by Prowazek and other investigators.
+
+
+TSETSE-FLIES AND NAGANA--One of the greatest factors in retarding the
+development of certain regions of Africa has been the presence of a
+small fly, little larger than the common house-fly. This is the
+tsetse-fly, _Glossina morsitans_ (fig. 165) renowned on account of the
+supposed virulence of its bite for cattle, horses and other domestic
+mammals.
+
+The technical characteristics of the tsetse-flies, or Glossinas, and
+their several species, will be found in a later chapter. We need
+emphasize only that they are blood-sucking Muscidæ and that, unlike the
+mosquitoes, the sexes resemble each other closely in structure of the
+mouth-parts, and in feeding habits.
+
+In 1894, Colonel David Bruce discovered that the fly was not in itself
+poisonous but that the deadly effect of its bite was due to the fact
+that it transmitted a highly pathogenic blood parasite, _Trypanosoma
+brucei_. This trypanosome Bruce had discovered in the blood of South
+African cattle suffering from a highly fatal disease known as "nagana".
+On inoculating the blood of infected cattle into horses and dogs he
+produced the disease and found the blood teeming with the causative
+organism. In the course of his work he established beyond question that
+the "nagana" and the tsetse-fly disease were identical.
+
+Tsetse-flies of the species _Glossina morsitans_, which fed upon
+diseased animals, were found capable of giving rise to the disease in
+healthy animals up to forty-eight hours after feeding. Wild tsetse-flies
+taken from an infected region to a region where they did not normally
+occur were able to transmit the disease to healthy animals. It was found
+that many of the wild animals in the tsetse-fly regions harbored
+_Trypanosoma brucei_ in their blood, though they showed no evidence of
+disease. As in the case of natives of malarial districts, these animals
+acted as reservoirs of the parasite. Non-immune animals subjected to the
+attacks of the insect carrier, quickly succumbed to the disease.
+
+A question of prime importance is as to whether the insect serves as an
+essential host of the pathogenic protozoan or whether it is a mere
+mechanical carrier. Bruce inclined to the latter view. He was unable to
+find living trypanosomes in the intestines or excrements of the fly or
+to produce the disease on the many occasions when he injected the
+excrement into healthy animals. Moreover, he had found that the
+experimental flies were infective only during the first forty-eight
+hours and that if wild flies were taken from the infected region, "kept
+without food for three days and then fed on a healthy dog, they never
+gave rise to the disease."
+
+Koch had early described what he regarded as sexual forms from the
+intestine of the fly but it remained for Kleine (1909) to experimentally
+demonstrate that a part of the life cycle of the parasite was undergone
+in the fly. Working with _Glossina palpalis_, he found that for a period
+of ten days or longer after feeding on an animal suffering from nagana
+it was non-infective, but that then it became infective and was able to
+transmit the disease for weeks thereafter. He discovered and described
+developmental stages of the parasite within the intestine of the insect.
+In other words, the tsetse-fly (in nature, _Glossina morsitans_), serves
+as an essential host, within which an important part of the life cycle
+of the parasite is undergone. These conclusions were quickly verified by
+Bruce and numerous other workers and are no longer open to question.
+Klein and Taute are even inclined to think that mechanical transmission
+plays practically no rôle in nature, unless the fly is interrupted while
+feeding and passes immediately to a new animal.
+
+
+TSETSE-FLIES AND SLEEPING SICKNESS OF MAN--About the beginning of the
+present century a hitherto little known disease of man began to attract
+great attention on account of its ravages in Uganda and the region of
+Victoria Nyanza in South Africa. It was slow, insiduous and absolutely
+fatal, characterized in its later stages by dullness, apathy, and
+finally absolute lethargy all day long, symptoms which gave it the name
+of "sleeping sickness."
+
+It was soon found that the disease was not a new one but that it had
+been known for over a hundred years on the west coast of Africa. Its
+introduction into Central and East Africa and its rapid spread have been
+attributed primarily to the development of the country, the formation of
+new trade routes and the free mingling of native tribes formerly
+isolated. It is estimated that in the first ten years of the present
+century there were approximately two hundred thousand deaths from the
+disease in the Uganda protectorate. In the British province Bugosa, on
+the Victoria Nyanza there were thirty thousand deaths in the period from
+1902-1905.
+
+While the disease is peculiarly African there are a number of instances
+of its accidental introduction into temperate regions. Slaves suffering
+from it were occasionally brought to America in the early part of the
+last century and cases have sometimes been imported into England. In
+none of the cases did the disease gain a foothold or spread at all to
+other individuals.
+
+In 1902 Dutton described a trypanosome, _T. gambiense_, which he and
+Forde had found the year before in the blood of a patient suffering from
+a peculiar type of fever in Gambia. In 1902-1903 Castellani found the
+same parasite in the cerebro-spinal fluid of sleeping-sickness patients
+and definitely reported it as the causative organism of the disease. His
+work soon found abundant confirmation, and it was discovered that the
+sleeping sickness was but the ultimate phase of the fever discovered by
+Dutton and Forde.
+
+When Castellani made known his discovery of the trypanosome of sleeping
+sickness, Brumpt, in France, and Sambon, in England, independently
+advanced the theory that the disease was transmitted by the tsetse-fly,
+_Glossina palpalis_. This theory was based upon the geographical
+distribution and epidemiology of the disease. Since then it has been
+abundantly verified by experimental evidence.
+
+Fortunately for the elucidation of problems relating to the methods of
+transfer of sleeping sickness, _Trypanosoma gambiense_ is pathogenic for
+many species of animals. In monkeys it produces symptoms very similar to
+those caused in man. Bruce early showed that _Glossina palpalis_ "fed on
+healthy monkeys eight, twelve, twenty-four and forty-eight hours after
+having fed on a native suffering from trypanosomiasis, invariably
+transmitted the disease. After three days the flies failed to transmit
+it." In his summary in Osler's Modern Medicine, he continues "But this
+is not the only proof that these flies can carry the infective agent. On
+the lake shore there was a large native population among whom we had
+found about one-third to be harboring trypanosomes in their blood. The
+tsetse-flies caught on this lake shore, brought to the laboratory in
+cages, and placed straightway on healthy monkeys, gave them the disease
+in every instance, and furnished a startling proof of the danger of
+loitering along the lake shore among those infected flies."
+
+As in the case of nagana, Bruce and most of the earlier investigators
+supposed the transmission of the sleeping sickness trypanosome by
+_Glossina palpalis_ to be purely mechanical. The work of Kleine (1909)
+clearly showed that for _Trypanosoma gambiense_ as well as for
+_Trypanosoma brucei_ the fly served as an essential host. Indeed, Kleine
+and many subsequent investigators are inclined to think that there is
+practically no mechanical transmission of trypanosomes from animal to
+animal by _Glossina_ in nature, and that the many successful experiments
+of the earlier investigators were due to the fact that they used wild
+flies which already harbored the transformed parasite rather than
+directly inoculated it from the blood of the diseased experimental
+animals. While the criticism is applicable to some of the work, this
+extreme view is not fully justified by the evidence at hand.
+
+Kleine states (1912) that _Glossina palpalis_ can no longer be regarded
+as the sole transmitter of sleeping sickness. Taute (1911) had shown
+that under experimental conditions _Glossina morsitans_ was capable of
+transferring the disease and Kleine calls attention to the fact that in
+German East Africa, in the district of the Rovuma River, at least a
+dozen cases of the disease have occurred recently, though only _Glossina
+morsitans_ exists in the district. It appears, however, that these cases
+are due to a different parasite, _Trypanosoma rhodesiense_. This
+species, found especially in north-east Rhodesia and in Nyassaland, is
+transferred by _Glossina morsitans_.
+
+Other workers maintain that the disease may be transmitted by various
+blood-sucking flies, or even bugs and lice which attack man. Fülleborn
+and Mayer (1907) have shown by conclusive experiments that _Aedes
+(Stegomyia) calopus_ may transmit it from one animal to another if the
+two bites immediately succeed each other.
+
+It is not possible that insects other than the tsetse-flies (and only
+certain species of these), play an important rôle in the transmission of
+the disease, else it would be much more wide-spread. Sambon (1908)
+pointed out that the hypothesis that is spread by _Aedes calopus_ is
+opposed by the fact that the disease never spread in the Antilles,
+though frequently imported there by West African slaves. The same
+observation would apply also to conditions in our own Southern States in
+the early part of the past century.
+
+Since _Glossina palpalis_ acts as an essential host of the parasite and
+the chief, if not the only, transmitter, the fight against sleeping
+sickness, like that against malaria and yellow fever, becomes primarily
+a problem in economic entomology. The minutest detail of the
+life-history, biology, and habits of the fly, and of its parasites and
+other natural enemies becomes of importance in attempts to eradicate the
+disease. Here we can consider only the general features of the subject.
+
+_Glossina palpalis_ lives in limited areas, where the forest and
+undergrowth is dense, along the lake shore or river banks. According to
+Hodges, the natural range from shore is under thirty yards, though the
+distance to which the flies may follow man greatly exceed this.
+
+It is a day feeder, a fact which may be taken advantage of in avoiding
+exposure to its attacks. The young are brought forth alive and
+full-grown, one every nine or ten days. Without feeding, they enter the
+ground and under favorable conditions, complete their development in a
+month or more.
+
+[Illustration: 137. Sleeping sickness concentration camp in German East
+Africa. Report of German Commission.]
+
+Methods of control of the disease must look to the prevention of
+infection of the flies, and to their avoidance and destruction. Along
+the first line, much was hoped from temporary segregation of the sick in
+regions where the fly was not found. On the assumption that the flies
+acted as carriers only during the first two or three days, it was
+supposed that even the "fly belts" would become safe within a few days
+after the sick were removed. The problem was found to be a much more
+difficult one when it was learned that after a given brief period the
+fly again became infective and remained so for an indeterminate period.
+Nevertheless, isolation of the sick is one of the most important
+measures in preventing the spread of the disease into new districts.
+Much, too, is being accomplished by moving native villages from the fly
+belts. (c.f. fig. 137.)
+
+All measures to avoid the flies should be adopted. This means locating
+and avoiding the fly belts as far as possible, careful screening of
+houses, and protection of the body against bites.
+
+Clearing the jungle along the water courses for some yards beyond the
+natural range of the fly has proved a very important measure. Castellani
+recommends that the area be one hundred yards and around a village three
+hundred yards at least.
+
+Detailed studies of the parasites and the natural enemies of the
+tsetse-fly are being undertaken and may ultimately yield valuable
+results.
+
+
+SOUTH AMERICAN TRYPANOSOMIASIS--The tsetse-flies are distinctively
+African in distribution and until recently there were no trypanosomes
+known to infest man in America. In 1909 Dr. Chagas, of Rio de Janeiro
+described a new species, _Trypanosoma cruzi_, pathogenic to man.
+
+_Trypanosoma cruzi_ is the causative organism of a disease common in
+some regions of Brazil, where it is known as "opilacao." It is
+especially to be met with in children and is characterized by extreme
+anemia, wasting, and stunted development associated with fever, and
+enlargement of the thyroid glands. The disease is transmitted by the
+bites of several species of assassin-bugs, or Reduviidæ, notably by
+_Conorhinus megistus_. The evolution of the parasite within the bug has
+been studied especially by Chagas and by Brumpt. From the latter's text
+we take the following summary.
+
+The adult trypanosomes, ingested by a _Conorhinus megistus_, of any
+stage, first change into Crithidia-like forms and then those which
+remain in the stomach become ovoid and non-motile. Brumpt found these
+forms in immense numbers, in a _Conorhinus_ which had been infested
+fourteen months before. The forms which pass into the intestine quickly
+assume the _Crithidia_ form and continue to develop rapidly under this
+form. Some weeks later they evolve into the trypanosome forms,
+pathogenic for man. They then pass out with the excrement of the bug and
+infect the vertebrate host as soon as they come in contact with any
+mucous layer (buccal, ocular or rectal). More rarely they enter through
+the epidermis.
+
+Brumpt showed that the development could take place in three species;
+bed-bugs (_Cimex lectularius_, _C. hemipterus_) and in the tick
+_Ornithodoros moubata_. The evolution proceeds in the first two species
+of bed-bugs as rapidly as in Conorhinus, or even more rapidly, but they
+remain infective for a much shorter time and hence Brumpt considers that
+they play a much less important rôle in the spread of the disease.
+
+_Conorhinus megistus_, like related forms in our Southern States, very
+commonly frequents houses and attacks man with avidity. Chagas states
+that the bites are painless and do not leave any traces. They are
+usually inflicted on the lips, or the cheeks and thus the buccal mucosa
+of a sleeper may be soiled by the dejections of the insect and the bite
+serving as a port of entry of the virus, remain unnoticed.
+
+The possibility of some of our North American Reduviidæ playing a
+similar rôle in the transmission of disease should not be overlooked.
+
+
+LEISHMANIOSES AND INSECTS--Closely related to the trypanosomes is a
+group of intracellular parasites which have recently been grouped by
+Ross under the genus _Leishmania_. Five species are known to affect man.
+Three of these produce local skin infestations, but two of them,
+_Leishmania donovani_ and _L. infantum_, produce serious and often fatal
+systemic diseases.
+
+The first of these, that produced by _L. donovani_, is an exceedingly
+virulent disease common in certain regions of India and China. It is
+commonly known as "Kala-azar," or "dum-dum" fever, and more technically
+as tropical leishmaniasis. Patton (1907) believes that the parasite is
+transmitted by the bed-bug _Cimex hemipterus_, and has described a
+developmental cycle similar to that which can be found in artificial
+cultures. On the other hand, Donovan was unable to confirm Patton's work
+and believes that the true intermediate host is a Reduviid bug,
+_Conorhinus rubrofasciatus_.
+
+_Leishmania infantum_ is the cause of the so-called infantile splenic
+leishmaniasis, occurring in northern Africa, Spain, Portugal, Italy, and
+possibly other parts of Europe. The parasite occurs habitually in the
+dog and is only accidentally transferred to children. Alvares and da
+Silva, in Portugal (according to Brumpt, 1913) have found that the
+excrement of a flea from a diseased dog contains flagellates, and they
+suggest that the infection may be transmitted by the accidental
+inoculation of this excrement by means of the proboscis of the flea, as
+has been thought to occur in the case of the plague. To this Brumpt
+objects that they and other workers who thought to trace the development
+of _Leishmania infantum_ were apparently misled by the presence of a
+harmless _Herpetomonas_ which infests dog fleas in all countries, even
+where the leishmaniasis is unknown.
+
+Basile (1910 and 1911) however, carried on numerous experiments
+indicating that the disease was transferred from children to dogs and
+from dog to dog by the dog flea, and was able to find in the tissues of
+the insects forms perfectly identical with those found in children and
+in dogs suffering from leishmaniasis. He also found that _Pulex
+irritans_ was capable of acting as the carrier.
+
+Of the cutaneous type of leishmaniasis, the best known is the so-called
+"Oriental sore," an ulcerative disease of the skin which is epidemic in
+many tropical and subtropical regions. The causative organism is
+_Leishmania tropica_, which occurs in the diseased tissues as bodies
+very similar to those found in the spleen in cases of Kala-azar. The
+disease is readily inoculable and there is no doubt that it may be
+transferred from the open sores to abraded surfaces of a healthy
+individual by house-flies. It is also believed by a number of
+investigators that it may be transferred and directly inoculated by
+various blood-sucking insects.
+
+
+TICKS AND DISEASES OF MAN AND ANIMALS
+
+We have seen that the way to the discoveries of the relations of
+arthropods to disease was pointed out by the work of Leuckart and
+Melnikoff on the life cycle of _Dipylidium_, and of Fedtschenko and
+Manson on that of _Filaria_. They dealt with grosser forms, belonging to
+well-recognized parasitic groups.
+
+This was long before the rôle of any insect as a carrier of pathogenic
+micro-organisms had been established, and before the Protozoa were
+generally regarded as of importance in the causation of disease. The
+next important step was taken in 1889 when Smith and Kilbourne
+conclusively showed that the so-called Texas fever of cattle, in the
+United States, is due to an intracorpuscular blood parasite transmitted
+exclusively by a tick. This discovery, antedating by eight years the
+work on the relation of the mosquito to malaria, had a very great
+influence on subsequent studies along these lines.
+
+While much of the recent work has dealt with the true insects, or
+hexapods, it is now known that several of the most serious diseases of
+animals, and at least two important diseases of man are tick borne.
+These belong to the types known collectively as _babesioses_ (or
+"_piroplasmoses_"), and _spirochætoses_.
+
+The term _babesiosis_ is applied to a disease of man or animals which is
+caused by minute protozoan parasites of the genus _Babesia_, living in
+the red blood corpuscles. These parasites have usually been given the
+generic name _Piroplasma_ and hence the type of disease which they cause
+is often referred to as "_piroplasmosis_." The best known illustration
+is the disease known in this country as Texas fever of cattle.
+
+
+CATTLE TICKS AND TEXAS FEVER--The cattle disease, which in the United
+States is known as Texas fever, is a widely distributed, exceedingly
+acute disease. In Australia it is known as _redwater fever_ and in
+Europe as hæmoglobinuria, due to the fact that the urine of the diseased
+animals is discolored by the breaking down of the red blood corpuscles
+infested by the parasite.
+
+In their historical discussion, Smith and Kilbourne, point out that as
+far back as 1796 it was noted that Southern cattle, in a state of
+apparent health, might spread a fatal disease among Northern herds. As
+observations accumulated, it was learned that this infection was carried
+only during the warm season of the year and in the depth of winter
+Southern cattle were harmless. Moreover, Southern cattle after remaining
+for a short time in the North lost their power to transmit the disease,
+and the same was true of cattle which had been driven for a considerable
+distance.
+
+Very significant was the fact that the infection was not communicated
+directly from the Southern to Northern cattle but that the ground over
+which the former passed was infected by them, and that the infection was
+transmitted thence to susceptible cattle _after a period of not less
+than thirty days had elapsed_.
+
+Of course a disease as striking as this, and which caused such enormous
+losses of cattle in the region invaded was fruitful in theories
+concerning its causation. The most widespread was the belief that
+pastures were infected by the saliva, urine, or manure of Southern
+cattle. There were not wanting keen observers who suggested that the
+disease was caused by ticks, but little weight was given to their view.
+
+Various workers had described bacteria which they had isolated from the
+organs of the diseased animals, but their findings could not be
+verified. In 1889, Smith and Kilbourne discovered a minute, pear-shaped
+organism (fig. 138) in the red blood corpuscles of a cow which had
+succumbed to Texas fever. On account of their shape they were given the
+generic name _Pyrososma_ and because they were usually found two in a
+corpuscle, the specific name, _bigeminum_. It is now generally accepted
+that the parasite is the same which Babes had observed the year before
+in Roumanian cattle suffering from hæmoglobinuria, and should be known
+as _Babesia bovis_ (Babes).
+
+[Illustration: 138. Babesia bovis in blood corpuscles. After Calli.]
+
+[Illustration: 139. The cattle tick (Boophilus annulatus). (_a_) Female;
+(_b_) male. After Comstock.]
+
+By a series of perfectly conclusive experiments carried on near
+Washington, D.C., Smith and Kilbourne showed that this organism was
+carried from Southern cattle to non-immune animals by the so-called
+Southern cattle tick, _Boophilus annulatus_ (= _Margaropus annulatus_)
+(fig. 139).
+
+Of fourteen head of native cattle placed in a field with tick-infested
+Northern cattle all but two contracted the disease. This experiment was
+repeated with similar results. Four head of native cattle kept in a plot
+with three North Carolina cattle which had been carefully freed from
+ticks remained healthy. A second experiment the same year gave similar
+results.
+
+Still more conclusive was the experiment showing that fields which had
+not been entered by Southern cattle but which had been infected by
+mature ticks taken from such animals would produce Texas fever in native
+cattle. On September 13, 1889, several thousand ticks collected from
+cattle in North Carolina three and four days before, were scattered in a
+small field near Washington. Three out of four native animals placed in
+this field contracted the disease. The fourth animal was not examined as
+to its blood but it showed no external symptoms of the disease.
+
+[Illustration: 140. Hyalomma ægypticum. After Nuttall and Warburton.]
+
+In these earlier experiments it was believed that the cattle tick acted
+as a carrier of the disease between the Southern cattle and the _soil_
+of the Northern pastures. "It was believed that the tick obtained the
+parasite from the blood of its host and in its dissolution on the
+pasture a certain resistant spore form was set free which produced the
+disease when taken in with the food." The feeding of one animal for some
+time with grass from the most abundantly infected field, without any
+appearance of the disease, made this hypothesis untenable.
+
+In the experimental work in 1890 the astonishing fact was brought out
+that the disease was conveyed neither by infected ticks disintegrating
+nor by their directly transferring the parasite, but that it was
+conveyed by the young hatched from eggs of infected ticks. In other
+words, the disease was hereditarily transferred to ticks of the second
+generation and they alone were capable of conveying it.
+
+Thus was explained the fact that Texas fever did not appear immediately
+along the route of Southern cattle being driven to Northern markets but
+that after a certain definite period it manifested itself. It was
+conveyed by the progeny of ticks which had dropped from the Southern
+cattle and deposited their eggs on the ground.
+
+These results have been fully confirmed by workers in different parts of
+the world,--notably by Koch, in Africa, and by Pound, in Australia.
+
+The disease is apparently transmitted by _Boophilus annulatus_ alone, in
+the United States, but it, or an almost identical disease, is conveyed
+by _Ixodes hexagonus_ in Norway, _Ixodes ricinus_ in Finland and France
+and by the three species, _Boophilus decoloratus_, _Hyalomma ægypticum_
+(fig. 140 and 141), and _Hæmaphysalis punctata_ in Africa.
+
+[Illustration: 141. Hyalomma ægypticum. Capitulum of female; (_a_)
+dorsal, (_b_) ventral aspect.]
+
+In spite of the detailed study which it has received, the life cycle of
+_Babesia bovis_ has not been satisfactorily worked out. The asexual
+reproduction in the blood of the vertebrate host has been described but
+the cycle in the tick is practically unknown.
+
+More successful attempts have been made to work out the life cycle of a
+related species, _Babesia canis_, which causes malignant jaundice in
+dogs in Africa and parts of Southern Europe. In this instance, also, the
+disease is transmitted by heredity to the ticks of the second
+generation. Yet the larval, or "seed ticks," from an infected female are
+not capable of conveying the disease, but only the nymphs and adults.
+Still more complicated is the condition in the case of _Babesia ovis_ of
+sheep, which Motas has shown can be conveyed solely by the adult,
+sexually mature ticks of the second generation.
+
+In _Babesia canis_, Christopher (1907) observed developmental stages in
+the tick. He found in the stomach of adult ticks, large motile
+club-shaped bodies which he considered as oökinetes. These bodies pass
+to the ovaries of the tick and enter the eggs where they become globular
+in form and probably represent an oocyst. This breaks up into a number
+of sporoblasts which enter the tissues of the developing tick and give
+rise to numerous sporozoites, which collect in the salivary glands and
+thence are transferred to the vertebrate host. A number of other species
+of _Babesia_ are known to infest vertebrates and in all the cases where
+the method has been worked out it has been found that the conveyal was
+by ticks. We shall not consider the cases more fully here, as we are
+concerned especially with the method of transfer of human diseases.
+
+
+TICKS AND ROCKY MOUNTAIN SPOTTED FEVER OF MAN--Ever since 1873 there has
+been known in Montana and Idaho a peculiar febrile disease of man, which
+has gained the name of "Rocky Mountain spotted fever." Its onset is
+marked by chills and fever which rapidly become acute. In about four to
+seven days there appears a characteristic eruption on the wrists, ankles
+or back, which quickly covers the body.
+
+McClintic (1912) states that the disease has now been reported from
+practically all of the Rocky Mountain States, including Arizona,
+California, Colorado, Idaho, Montana, Nevada, Oregon, Utah, Washington,
+and Wyoming. "Although the disease is far more prevalent in Montana and
+Idaho than in any of the other States, its spread has assumed such
+proportions in the last decade as to call for the gravest consideration
+on the part of both the state and national health authorities. In fact,
+the disease has so spread from state to state that it has undoubtedly
+become a very serious interstate problem demanding the institution of
+measures for its control and suppression."
+
+A peculiar feature of the Rocky Mountain spotted fever is a marked
+variation in its severity in different localities. In Montana, and
+especially in the famous Bitter Root Valley, from 33 per cent to 75 per
+cent of the cases result fatally. On the other hand, the fatality does
+not exceed four per cent in Idaho.
+
+In 1902, Wilson and Chowning reported the causative organism of spotted
+fever to be a blood parasite akin to the _Babesia_ of Texas fever, and
+made the suggestion that the disease was tick-borne. The careful studies
+of Stiles (1905) failed to confirm the supposed discovery of the
+organism, and the disease is now generally classed as due to an
+invisible virus. On the other hand, the accumulated evidence has fully
+substantiated the hypothesis that it is tick-borne.
+
+According to Ricketts (1907) the experimental evidence in support of
+this hypothesis was first afforded by Dr. L. P. McCalla and Dr. H. A.
+Brereton, in 1905. These investigators transmitted the disease from man
+to man in two experiments. "The tick was obtained 'from the chest of a
+man very ill with spotted fever' and 'applied to the arm of a man who
+had been in the hospital for two months and a half, and had lost both
+feet from gangrene due to freezing.' On the eighth day the patient
+became very ill and passed through a mild course of spotted fever,
+leaving a characteristic eruption. The experiment was repeated by
+placing the tick on a woman's leg and she likewise was infected with
+spotted fever."
+
+The most detailed studies were those of the late Dr. H. T. Ricketts, and
+it was he who clearly established the tick hypothesis. In the summer of
+1906 he found that guinea pigs and monkeys are very susceptible to
+spotted fever and can readily be infected by inoculation of blood from
+patients suffering from the disease. This opened the way to experimental
+work on tick transmission. A female tick was fed upon an infected guinea
+pig for two days, removed and isolated for two days and then placed upon
+a healthy guinea pig. After an incubation period of three and a half
+days the experimental animal contracted a well-marked case of the
+disease.
+
+A similar result was obtained at the same time by King, and later in the
+season Ricketts proved that the male tick was also capable of
+transmitting the disease. He found that there was a very intimate
+relation of the virus to the tick and that the transmission must be
+regarded as biological throughout. Ticks remained infective as long as
+they lived and would feed for a period of several months. If they
+acquired the disease in the larval or nymphal stage they retained it
+during molting and were infective in the subsequent stages. In a few
+cases the larvæ from an infected female were infective.
+
+The evidence indicated that the tick suffers from a relatively harmless,
+generalized infection and the virus proliferates in its body. The
+disease probably is transferred through the salivary secretion of the
+tick since inoculation experiments show that the salivary glands of the
+infected adult contain the virus.
+
+It is probable that in nature the reservoir of the virus of spotted
+fever is some one or more of the native small animals. Infected ticks
+have been found in nature, and as various wild animals are susceptible
+to the disease, it is obvious that it may exist among them unnoticed.
+Wilson and Chowning suggested that the ground squirrel plays the
+principal rôle.
+
+Unfortunately, much confusion exists regarding the correct name of the
+tick which normally conveys the disease. In the medical literature it is
+usually referred to as _Dermacentor occidentalis_, but students of the
+group now agree that it is specifically distinct. Banks has designated
+it as _Dermacentor venustus_ and this name is used in the publications
+of the Bureau of Entomology. On the other hand, Stiles maintains that
+the common tick of the Bitter Root Valley, and the form which has been
+collected by the authors who have worked on Rocky Mountain spotted fever
+in that region, is separable from _D. venustus_, and he has described it
+under the name of _Dermacentor andersoni_.
+
+Mayer (1911) has shown experimentally that spotted fever may be
+transmitted by several different species of ticks, notably _Dermacentor
+marginatus_, _Dermacentor variabilis_ and _Amblyomma americanum_. This
+being the case, the question of the exact systematic status of the
+species experimented upon in the Bitter Root Valley becomes less
+important, for since _Dermacentor occidentalis_, _Dermacentor venustus_
+and _Dermacentor andersoni_ all readily attack man, it is probable that
+either species would readily disseminate the disease if it should spread
+into their range.
+
+Hunter and Bishop (1911) have emphasized the fact that in the eastern
+and southern United States there occur several species which attack man,
+and any one of which might transmit the disease from animal to animal
+and from animal to man. The following species, they state, would
+probably be of principal importance in the Southern and Eastern States:
+the lone star tick (_Amblyomma americanum_); the American dog tick
+(_Dermacentor variabilis_); and the gulf-coast tick (_Amblyomma
+maculatum_). In the extreme southern portions of Texas, _Amblyomma
+cajennense_, is a common pest of man.
+
+Since the evidence all indicates that Rocky Mountain spotted fever is
+transmitted solely by the tick, and that some of the wild animals serve
+as reservoirs of the virus, it is obvious that personal prophylaxis
+consists in avoiding the ticks as fully as possible, and in quickly
+removing those which do attack. General measures along the line of tick
+eradication must be carried out if the disease is to be controlled. That
+such measures are feasible has been shown by the work which has been
+done in controlling the tick-borne Texas fever of cattle, and by such
+work as has already been done against the spotted fever tick, which
+occurs on both wild and domestic animals. Detailed consideration of
+these measures is to be found in the publications of the Public Health
+and Marine Hospital Service, and the Bureau of Entomology. Hunter and
+Bishopp give the following summarized recommendations for control or
+eradication measures in the Bitter Root Valley.
+
+(1) A campaign of education, whereby all the residents of the valley
+will be made thoroughly familiar with the feasibility of the plan of
+eradication, and with what it will mean in the development of the
+valley.
+
+(2) The obtaining of legislation to make it possible to dip or oil all
+live stock in the Bitter Root Valley.
+
+(3) The obtaining of an accurate census of the horses, cattle, sheep,
+mules, and dogs in the valley.
+
+(4) The construction of ten or more dipping vats.
+
+(5) The providing of materials to be used in the dipping mixture.
+
+(6) The organization of a corps of workers to carry on the operations.
+
+(7) The systematic dipping of the horses, cattle, sheep, and dogs of the
+valley on a definite weekly schedule from approximately March 10 to June
+9.
+
+(8) The treatment by hand of the animals in localities remote from vats,
+on the same schedule.
+
+They estimate that after three seasons' operations a very small annual
+expenditure would provide against reinfestation of the valley by the
+incoming of cattle from other places.
+
+Supplementary measures consist in the killing of wild mammals which may
+harbor the tick; systematic burning of the brush and debris on the
+mountain side; and in clearing, since the tick is seldom found on land
+under cultivation.
+
+
+
+
+CHAPTER X
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA [_Continued_]
+
+
+ARTHROPODS AND SPIROCHÆTOSES OF MAN AND ANIMALS
+
+The term spirochætoses is applied to diseases of man or animals which
+are due to protistan parasites belonging to the group of slender, spiral
+organisms known as spirochætes.
+
+There has been much discussion concerning the relationship Of the
+spirochætes. Formerly, they were regarded as bacteria closely related to
+the forms grouped in the genus _Spirillum_. The results of the detailed
+study which the spirochætes have received in recent years, have led most
+of the workers to consider them as belonging to the protozoa. The merits
+of the discussion we are not concerned with here, but rather with the
+fact that a number of diseases caused by spirochætes are
+arthropod-borne. The better known of these we shall discuss.
+
+
+AFRICAN RELAPSING FEVER OF MAN--It has long been known to the natives of
+Africa and to travelers in that country, that the bite of a certain
+tick, _Ornithodoros moubata_, may be followed by severe or even fatal
+fever of the relapsing type. Until recent years, it was supposed that
+the effect was due to some special virulence of the tick, just as nagana
+of cattle was attributed to the direct effect of the bite of the
+tsetse-fly. The disease is commonly known as "tick-fever" or by the
+various native names of the tick.
+
+In 1904, Ross and Milne, in Uganda, and Dutton and Todd on the Congo,
+discovered that the cause of the disease is a spirochæte which is
+transmitted by the tick. This organism has been designated by Novy and
+Knapp as _Spirochæta duttoni_.
+
+_Ornithodoros moubata_ (fig. 142), the carrier of African relapsing
+fever, or "tick-fever," is widely distributed in tropical Africa, and
+occurs in great numbers in the huts of natives, in the dust, cracks and
+crevices of the dirt floors, or the walls. It feeds voraciously on man
+as well as upon birds and mammals. Like others of the _Argasidæ_, it
+resembles the bed-bug in its habit of feeding primarily at night. Dutton
+and Todd observed that the larval stage is undergone in the egg and that
+the first free stage is that of the octopod nymph.
+
+[Illustration: 142. Ornithodoros moubata. (_a_) Anterior part of venter;
+(_b_) second stage nymph; (_c_) capitulum; (_d_) dorsal and (_e_)
+ventral aspect of female; (_f_) ventral aspect of nymph; (_g_) capitulum
+of nymph. After Nuttall and Warburton.]
+
+The evidence that the fever is transmitted by this tick is conclusive.
+Koch found that from five per cent to fifteen per cent, and in some
+places, fifty per cent of the ticks captured, harbored the spirochæte.
+The disease is readily transmitted to monkeys, rats, mice and other
+animals and the earlier experiments along these lines have been
+confirmed by many workers.
+
+Not only are the ticks which have fed on infected individuals capable of
+conveying the disease to healthy animals but they transmit the causative
+organism to their progeny. Thus Möllers (1907), working in Berlin,
+repeatedly infected monkeys through the bites of nymphs which had been
+bred in the laboratory from infected ticks. Still more astonishing was
+his discovery that ticks of the third generation were infective. In
+other words, if the progeny of infected ticks were fed throughout life
+on healthy animals, and on maturity deposited eggs, the nymphs which
+hatched from these eggs would still be capable of carrying the
+infection.
+
+The developmental cycle of the spirochæte within the tick has not been
+fully worked out, though the general conclusions of Leishman (1910) have
+been supported by the recent works of Balfour (1911 and 1912), and
+Hindle (1912), on the life cycle of spirochætes affecting fowls.
+
+_Spirochæta duttoni_ ingested by _Ornithodoros moubata_ apparently
+disappear within a few days, but Leishman believed that in reality they
+break up into minute granules which are to be found in the alimentary
+canal, the salivary glands and the Malpighian tubes of the tick. These
+granules, or "coccoid bodies," as Hindle calls them, are supposed to be
+the form in which the spirochætes infect the new host. We shall see
+later that Marchoux and Couvy (1913) dissent wholly from this
+interpretation.
+
+According to Leishman, and Hindle, the coccoid bodies are not injected
+into the vertebrate host with the saliva of the tick, as are the
+sporozoites of malaria with that of the mosquito. Instead, they pass out
+with the excrement and secondarily gain access to the wound inflicted by
+the tick.
+
+Nuttall (1912) calls attention to the fact that the geographical
+distribution of _Ornithodoros moubata_ is far wider than our present
+records show for the distribution of the relapsing fever in man and that
+there is every reason to fear the extension of the disease. Huts where
+the ticks occur should be avoided and it should be remembered that in
+infected localities there is special danger in sleeping on the ground.
+
+
+EUROPEAN RELAPSING FEVER--There is widely distributed in Europe a type
+of relapsing fever which is caused by _Spirochæta recurrentis_. It has
+long been supposed that this disease is spread by the bed-bug and there
+is some experimental evidence to show that it may be conveyed by these
+insects.
+
+In 1897, Tictin found that he could infect monkeys by inoculating the
+contents of bed-bugs which had fed upon a patient within forty-eight
+hours. Nuttall, in 1907, in one experiment succeeded in transmitting
+_Spirochæta recurrentis_ from mouse to mouse by bites of bed-bugs. The
+bugs, thirty-five in number, were transferred at short intervals from
+one mouse to another, not being allowed to take a full meal on the
+first, or infected mouse.
+
+On the other hand, there is much clinical evidence to show that the
+European relapsing fever like various other types of the disease is
+transmitted from man to man by head and body lice (_Pediculus humanus_
+and _Pediculus corporis_).
+
+Interesting supplementary evidence is that of Bayon's observations
+(1912), in Moscow. "Having visited the big municipal night hospitals at
+Moscow I soon noticed that they were kept with such scrupulous
+cleanliness, disinfected so lavishly, the beds of iron, the floor
+cemented, that it was not possible for bed-bugs to thrive to any extent
+on the premises. The people sleeping there were allowed, however, to
+sleep in their own clothes. The introduction of these model homes had
+not had any effect on the incidence of relapsing fever, for the places
+were still hot-beds of the fever during winter. On the other hand,
+though I changed my rooms several times, I found bugs in every
+successive lodging, and I was told in Moscow, this can hardly be
+avoided. Yet no foreigner, or Russian of the better class, ever catches
+relapsing fever. To this may be added the fact that when I asked for
+clothes-lice and promised to pay a kopec for two, the attendants from
+the night hostel brought me next morning a small ounce bottle crammed
+with _Pediculus capitis_ (= _P. humanus_), and _Pediculus vestimentorum_
+(= _P. corporis_) collected off the sleepers. If relapsing fever were
+transmitted by bed-bugs, it would be much more disseminated than it is
+at present in Moscow."
+
+Direct experimental evidence of the agency of lice in transmitting
+relapsing fever is especially clear in the case of a type of the disease
+prevalent in parts of North Africa. We shall consider this evidence
+later.
+
+
+OTHER TYPES OF RELAPSING FEVER OF MAN--In addition to the three types of
+human relapsing fever already referred to, several others have been
+distinguished and have been attributed to distinct species of
+spirochætes. The various spirochætoses of man are:
+
+African, caused by _S. duttoni_; European, caused by _S. recurrentis_;
+North African, caused by _S. berbera_; East African, caused by _S.
+rossi_; East Indian, caused by _S. carteri_; North American, caused by
+_S. novyi_; South American, caused by _S. duttoni_ (?).
+
+Nuttall (1912) in his valuable résumé of the subject, has emphasized
+that "in view of the morphological similarity of the supposedly
+different species of spirochætes and their individual variations in
+virulence, we may well doubt if any of the 'species' are valid. As I
+pointed out four years ago, the various specific names given to the
+spirochætes causing relapsing fever in man may be used merely for
+convenience _to distinguish strains or races_ of different origin. They
+cannot be regarded as valid names, in the sense of scientific
+nomenclature, for virulence and immunity reactions are not adequate
+tests of specificity."
+
+
+NORTH AFRICAN RELAPSING FEVER OF MAN--The type of human relapsing fever
+to be met with in Algeria, Tunis, and Tripoli, is due to a _Spirochæta_
+to which does not differ morphologically from _Spirochæta duttoni_, but
+which has been separated on biological grounds as _Spirochæta berberi_.
+
+Experimenting with this type of disease in Algeria, Sergent and Foly
+(1910), twice succeeded in transmitting it from man to monkeys by
+inoculation of crushed body lice and in two cases obtained infection of
+human subjects who had received infected lice under their clothing and
+who slept under coverings harboring many of the lice which had fed upon
+a patient. Their results were negative with _Argas persicus_, _Cimex
+lectularius_, _Musca domestica_, _Hæmatopinus spinulosus_ and
+_Ceratophyllus fasciatus_. They found body lice associated with every
+case of relapsing fever which they found in Algeria.
+
+Nicolle, Blaizot, and Conseil (1912) showed that the louse did not
+transmit the parasite by its bite. Two or three hours after it has fed
+on a patient, the spirochætes begin to break up and finally they
+disappear, so that after a day, repeated examinations fail to reveal
+them. They persist, nevertheless, in some unknown form, for if the
+observations are continued they reappear in eight to twelve days. These
+new forms are virulent, for a monkey was infected by inoculating a
+single crushed louse which had fed on infected blood fifteen days
+before.
+
+Natural infection is indirect. Those attacked by the insect scratch, and
+in this act they excoriate the skin, crush the lice and contaminate
+their fingers. The least abrasion of the skin serves for the entrance of
+the spirochætes. Even the contact of the soiled fingers on the various
+mucosa, such as the conjunctive of the eye, is sufficient.
+
+As in the case of _Spirochæta duttoni_, the organism is transmitted
+hereditarily in the arthropod vector. The progeny of lice which have fed
+on infected blood may themselves be infective.
+
+
+SPIROCHÆTOSIS OF FOWLS--One of the best known of the spirochætes
+transmitted by arthropods is _Spirochæta gallinarum_, the cause of a
+very fatal disease of domestic fowls in widely separated regions of the
+world. According to Nuttall, it occurs in Southeastern Europe, Asia,
+Africa, South America and Australia.
+
+In 1903, Marchoux and Salimbeni, working in Brazil, made the first
+detailed study of the disease, and showed that the causative organism is
+transmitted from fowl to fowl by the tick _Argas persicus_. They found
+that the ticks remained infective for at least five months. Specimens
+which had fed upon diseased birds in Brazil were sent to Nuttall and he
+promptly confirmed the experiments. Since that date many investigators,
+notably Balfour and Hindle, have contributed to the elucidating of the
+life-cycle of the parasite. Since it has been worked out more fully than
+has that of any of the human spirochætes, we present Hindle's diagram
+(fig. 143) and quote the brief summary from his preliminary paper
+(1911_b_).
+
+"Commencing with the ordinary parasite in the blood of the fowl, the
+spirochæte grows until it reaches a certain length (16-19µ) and then
+divides by transverse division. This process is repeated, and is
+probably the only method of multiplication of the parasite within the
+blood. When the spirochætes disappear from the circulation, some of them
+break up into the coccoid bodies which, however, do not usually develop
+in the fowl. When the spirochætes are ingested by _Argas persicus_, some
+of them pass through the gut wall into the coelomic fluid. From this
+medium they bore their way into the cells of the various organs of the
+tick and there break up into a number of coccoid bodies. These
+intracellular forms multiply by ordinary fission in the cells of the
+Malpighian tubules and gonads. Some of the coccoid bodies are formed in
+the lumen of the gut and Malpighian tubules. The result is that some of
+the coccoid bodies may be present in the Malpighian secretion and
+excrement of an infected tick and when mixed with the coxal fluid may
+gain entry into another fowl by the open wound caused by the tick's
+bite. They then elongate and redevelop into ordinary spirochætes in the
+blood of the fowl, and the cycle may be repeated."
+
+[Illustration: 143. Spirochæta gallinarum. After Hindle.]
+
+Hindle's account is clear cut and circumstantial, and is quite in line
+with the work of Balfour, and of Leishman. Radically different is the
+interpretation of Marchoux and Couvy (1913). These investigators
+maintain that the granules localized in the Malpighian tubules in the
+larvæ and, in the adult, also in the ovules and the genital ducts of the
+male and female, are not derived from spirochætes but that they exist
+normally in many acariens. They interpret the supposed disassociation
+of the spirochæte into granules as simply the first phase, not of a
+process of multiplication, but of a degeneration ending in the death of
+the parasite. The fragmented chromatin has lost its affinity for stains,
+remaining always paler than that of the normal spirochætes. On the other
+hand, the granules of Leishman stain energetically with all the basic
+stains.
+
+Further, according to Marchoux and Couvy, infection takes place without
+the emission of the coxal fluid and indeed, soiling of the host by the
+coxal fluid diluting the excrement is exceptional. All of the organs of
+the Argasid are invaded by the parasites, but they pass from the
+coelom into the acini of the salivary glands and collect in its
+efferent canal. The saliva serves as the vehicle of infection.
+
+Thus, the question of the life cycle of _Spirochæta gallinarum_, and of
+spirochætes in general, is an open one.
+
+It should be noted that _Argas persicus_, the carrier of _Spirochæta
+gallinarum_, is a common pest of poultry in the southwestern United
+States. Though the disease has not been reported from this country,
+conditions are such that if accidentally introduced, it might do great
+damage.
+
+
+OTHER SPIROCHÆTE DISEASES OF ANIMALS--About a score of other blood
+inhabiting spirochætes have been reported as occurring in mammals, but
+little is known concerning their life-histories. One of the most
+important is _Spirochæta theileri_ which produces a spirochætosis of
+cattle in the Transvaal. Theiler has determined that it is transmitted
+by an Ixodid tick, _Margaropus decoloratus_.
+
+
+TYPHUS FEVER AND PEDICULIDÆ
+
+Typhus is an acute, and continued fever, formerly epidemically prevalent
+in camps, hospitals, jails, and similar places where persons were
+crowded together under insanitary conditions. It is accompanied by a
+characteristic rash, which gives the disease the common name of
+"spotted" or "lenticular" fever. The causative organism is unknown.
+
+Typhus fever has not generally been supposed to occur in the United
+States, but there have been a few outbreaks and sporadic cases
+recognized. According to Anderson and Goldberger (1912_a_), it has been
+a subject of speculation among health authorities why, in spite of the
+arrival of occasional cases in this country and of many persons from
+endemic foci of the disease, typhus fever apparently does not gain a
+foothold in the United States. These same workers showed that the
+so-called Brill's disease, studied especially in New York City, is
+identical with the typhus fever of Mexico and of Europe.
+
+The conditions under which the disease occurs and under which it spreads
+most rapidly are such as to suggest that it is carried by some parasitic
+insect. On epidemiological grounds the insects most open to suspicion
+are the lice, bed-bugs and fleas.
+
+In 1909, Nicolle, Comte and Conseil, succeeded in transmitting typhus
+fever from infected to healthy monkeys by means of the body louse
+(_Pediculus corporis_). Independently of this work, Anderson and
+Goldberger had undertaken work along this line in Mexico, and in 1910
+reported two attempts to transmit the disease to monkeys by means of
+body lice. The first experiment resulted negatively, but the second
+resulted in a slight rise in temperature, and in view of later results
+it seems that this was due to infection with typhus.
+
+Shortly after, Ricketts and Wilder (1910) succeeded in transmitting the
+disease to the monkey by the bite of body lice in two experiments, the
+lice in one instance deriving their infection from a man and in another
+from the monkey. Another monkey was infected by typhus through the
+introduction of the feces and abdominal contents of infested lice into
+small incisions. Experiments with fleas and bed-bugs resulted
+negatively.
+
+Subsequently, Goldberger and Anderson (1912_b_) indicated that the head
+louse (_Pediculus humanus_) as well, may become infected with typhus. In
+an attempt to transmit typhus fever (Mexican virus) from man to monkey
+by subcutaneous injection of a saline suspension of crushed head lice,
+the monkeys developed a typical febrile reaction with subsequent
+resistance to an inoculation of virulent typhus (Mexican) blood. In one
+of the three experiments to transmit the disease from man to monkey by
+means of the bite of the head louse, the animal bitten by the presumably
+infected head lice proved resistant to two successive immunity tests
+with virulent typhus blood.
+
+In 1910, Ricketts and Wilder reported an experiment undertaken with a
+view to determining whether the young of infected lice were themselves
+infected. Young lice were reared to maturity on the bodies of typhus
+patients, so that if the eggs were susceptible to infection at any stage
+of their development, they would have every opportunity of being
+infected within the ovary. The eggs of these infected lice were
+obtained, they were incubated, and the young lice of the second
+generation were placed on a normal rhesus monkey. The experimenters were
+unable to keep the monkey under very close observation during the
+following three or four weeks, but from the fact that he proved
+resistant to a subsequent immunity test they concluded that he probably
+owed this immunity to infection by these lice of the second generation.
+
+Anderson and Goldberger (1912_b_) object that due consideration was not
+given to the possibility of a variable susceptibility of the monkey to
+typhus. Their similar experiment was "frankly negative."
+
+Prophylaxis against typhus fever is, therefore, primarily a question of
+vermin extermination. A brief article by Dr. Goldberger (1914) so
+clearly shows the practical application of his work and that of the
+other investigators of the subject, that we abstract from it the
+following account:
+
+"In general terms it may be stated that association with a case of
+typhus fever in the absence of the transmitting insect is no more
+dangerous than is association with a case of yellow fever in the absence
+of the yellow fever mosquito. Danger threatens only when the insect
+appears on the scene."
+
+"We may say, therefore, that to prevent infection of the individual it
+is necessary for him only to avoid being bitten by the louse. In theory
+this may readily be done, for we know that the body louse infests and
+attaches itself almost entirely to the body linen, and that boiling
+kills this insect and its eggs. Individual prophylaxis is based
+essentially, therefore, on the avoidance of contact with individuals
+likely to harbor lice. Practically, however, this is not always as easy
+as it may seem, especially under the conditions of such intimate
+association as is imposed by urban life. Particularly is this the case
+in places such as some of the large Mexican cities, where a large
+proportion of the population harbors this vermin. Under such
+circumstances it is well to avoid crowds or crowded places, such as
+public markets, crowded streets, or public assemblies at which the
+'peon' gathers."
+
+"Community prophylaxis efficiently and intelligently carried out is,
+from a certain point of view, probably easier and more effective in
+protecting the individual than is the individual's own effort to guard
+himself. Typhus emphasizes, perhaps better than any other disease, the
+fact that fundamentally, sanitation and health are economic problems. In
+proportion as the economic condition of the masses has improved--that
+is, in proportion as they could afford to keep clean--the notorious
+filth disease has decreased or disappeared. In localities where it still
+prevails, its further reduction or complete eradication waits on a
+further improvement in, or extension of, the improved economic status of
+those afflicted. Economic evolution is very slow process, and, while
+doing what we can to hasten it, we must take such precautions as
+existing conditions permit, looking to a reduction in or complete
+eradication of the disease."
+
+"When possible, public bath houses and public wash houses, where the
+poor may bathe and do their washings at a minimum or without cost,
+should be provided. Similar provision should be made in military and
+construction camps. Troops in the field should be given the opportunity
+as frequently as possible to wash and _scald_ or _boil_ their body
+linen."
+
+"Lodging houses, cheap boarding houses, night shelters, hospitals, jails
+and prisons, are important factors in the spread and frequently
+constitute foci of the disease. They should receive rigid sanitary
+supervision, including the enforcement of measures to free all inmates
+of such institutions of lice on admission."
+
+"So far as individual foci of the disease are concerned these should be
+dealt with by segregating and keeping under observation all exposed
+individuals for 14 days--the period of incubation--from the last
+exposure, by disinfecting (boiling or steaming) the suspected bedding,
+body linen, and clothes, for the destruction of any possible vermin that
+they may harbor, and by fumigating (with sulphur) the quarters that they
+may have occupied."
+
+"It will be noted that nothing has been said as to the disposition of
+the patient. So far as the patient is concerned, he should be removed to
+'clean' surroundings, making sure that he does not take with him any
+vermin. This may be done by bathing, treating the hair with an
+insecticide (coal oil, tincture of larkspur), and a complete change of
+body linen. Aside from this, the patient may be treated or cared for in
+a general hospital ward or in a private house, provided the sanitary
+officer is satisfied that the new surroundings to which the patient has
+been removed are 'clean,' that is, free from vermin. Indeed, it is
+reasonably safe to permit a 'clean' patient to remain in his own home if
+this is 'clean,' for, as has already been emphasized, there can be no
+spread in the absence of lice. This is a common experience in native
+families of the better class and of Europeans in Mexico City."
+
+"Similarly the sulphur fumigation above prescribed may be dispensed with
+as unnecessary in this class of cases."
+
+
+
+
+CHAPTER XI
+
+SOME POSSIBLE, BUT IMPERFECTLY ESTABLISHED CASES OF ARTHROPOD
+TRANSMISSION OF DISEASE
+
+
+INFANTILE PARALYSIS OR ACUTE ANTERIOR POLIOMYELITIS
+
+The disease usually known in this country as infantile paralysis or,
+more technically, as acute anterior poliomyelitis, is one which has
+aroused much attention in recent years.
+
+The causative organism of infantile paralysis is unknown, but it has
+been demonstrated that it belongs to the group of filterable viruses. It
+gives rise to a general infection, producing characteristic lesions in
+the central nervous system. The result of the injury to the motor nerves
+is a more or less complete paralysis of the corresponding muscle. This
+usually manifests itself in the legs and arms. The fatal cases are
+usually the result of paralysis of the muscles of respiration. Of the
+non-fatal cases about 60 per cent remain permanently crippled in varying
+degrees.
+
+Though long known, it was not until about 1890 that it was emphasized
+that the disease occurs in epidemic form. At this time Medin reported
+his observations on an epidemic of forty-three cases which occurred in
+and around Stockholm in 1887. Since then, according to Frost (1911),
+epidemics have been observed with increasing frequency in various parts
+of the world. The largest recorded epidemics have been those in Vermont,
+1894, 126 cases; Norway and Sweden, 1905, about 1,500 cases; New York
+City, 1907, about 2,500 cases. Since 1907 many epidemics have been
+reported in the United States, and especially in the Northern States
+east of the Dakotas. In 1912 there were over 300 cases of the disease in
+Buffalo, N. Y., with a mortality of somewhat over 11 per cent.
+
+In view of the sudden prominence and the alarming spread of infantile
+paralysis, there have been many attempts to determine the cause, and the
+manner in which the disease spreads and develops in epidemic form. In
+the course of these studies, the question of possible transmission by
+insects was naturally suggested.
+
+C. W. Howard and Clark (1912) presented the results of studies in this
+phase of the subject. They dealt especially with the house-fly, bedbug,
+head, and body lice, and mosquitoes. It was found that the house-fly
+(_Musca domestica_) can carry the virus of poliomyelitis in an active
+state for several days upon the surface of the body and for several
+hours within the gastro-intestinal tract. Mosquitoes and lice were found
+not to take up or maintain the virus. On the other hand, the bedbug
+(_Cimex lectularius_) was found to take the virus from the infected
+monkeys and to maintain it in a living state within the body for a
+period of seven days. This was demonstrated by grinding up in salt
+solution, insects which had fed on poliomyelitic animals and injecting
+the filtrate into a healthy monkey. The experimenters doubted that the
+bedbug is a carrier of the virus in nature.
+
+Earlier in the same year, Brues and Sheppard published the results of an
+intensive epidemiological study of the outbreak of 1911, in
+Massachusetts. Special attention had been paid to the possibility of
+insect transfer and the following conclusion was reached:
+
+"Field work during the past summer together with a consideration of the
+epidemiology of the disease so far as known, points strongly toward
+biting flies as possible carriers of the virus. It seems probable that
+the common stable-fly (_Stomoxys calcitrans_ L.) may be responsible to a
+certain extent for the spread of acute epidemic poliomyelitis, possibly
+aided by other biting flies, such as _Tabanus lineola_. No facts which
+disprove such a hypothesis have as yet been adduced, and experiments
+based upon it are now in progress."
+
+As stated by Brues (1913), especial suspicion fell upon the stable-fly
+because:
+
+1. The blood-sucking habits of the adult fly suit it for the transfer of
+virus present in the blood.
+
+2. The seasonal abundance of the fly is very closely correlated with the
+incidence of the disease, rising rapidly during the summer and reaching
+a maximum in July and August, then slowly declining in September and
+October.
+
+3. The geographical distribution of the fly is, so far as can be
+ascertained, wider, or at least co-extensive with that of poliomyelitis.
+
+4. _Stomoxys_ is distinctly more abundant under rural conditions, than
+in cities and thickly populated areas.
+
+5. While the disease spreads over districts quickly and in a rather
+erratic way, it often appears to follow along lines of travel, and it is
+known that _Stomoxys_ flies will often follow horses for long distances
+along highways.
+
+6. In a surprisingly large number of cases, it appeared probable that
+the children affected had been in the habit of frequenting places where
+_Stomoxys_ is particularly abundant, i.e., about stables, barnyards,
+etc.
+
+The experiments referred to were carried on during the summer of 1912
+and in September Dr. Rosenau announced that the disease was transferred
+by the bite of the stable-fly.
+
+A monkey infected by inoculation was exposed to the bites of upwards of
+a thousand of the _Stomoxys_ flies daily, by stretching it at full
+length and rolling it in a piece of chicken wire, and then placing it on
+the floor of the cage in which the flies were confined. The flies fed
+freely from the first, as well as later, after paralysis had set in.
+Alternating with the inoculated monkey, healthy monkeys were similarly
+introduced into the cage at intervals. New monkeys were inoculated to
+keep a supply of such infected animals and additional healthy ones were
+exposed to the flies, which fed willingly and in considerable numbers on
+each occasion. "Thus the flies were given every opportunity to obtain
+infection from the monkeys, since the animals were bitten during
+practically every stage of the disease from the time of the inoculation
+of the virus till their death following the appearance of paralysis. By
+the same arrangement the healthy monkeys were likely to be bitten by
+flies that had previously fed during the various stages of the disease
+on the infected monkeys. The flies had meanwhile enjoyed the opportunity
+of incubating the virus for periods varying from the day or two which
+usually elapses between consecutive feedings, to the two or three-week
+period for which at least some (although a very small percentage) of the
+flies lived in the cage."
+
+"In all, twelve apparently healthy monkeys of a small Japan species were
+exposed to the flies in the manner described for the infected monkeys.
+Some were placed in the cage only once or twice and others a number of
+times after varying intervals. These exposures usually lasted for about
+half an hour, but were sometimes more protracted. No results were
+apparent until two or three weeks after the experiment was well under
+way, and then in rather rapid succession six of the animals developed
+symptoms of poliomyelitis. In three, the disease appeared in a virulent
+form, resulting in death, while the other three experienced transient
+tremblings, diarrhoea, partial paralysis and recovery."--Brues, 1913.
+
+Very soon after the announcement of the results of experiments by
+Rosenau and Brues, they were apparently conclusively confirmed by
+Anderson and Frost (1912), who repeated the experiments, at Washington.
+They announced that through the bites of the _Stomoxys_ flies that had
+previously fed on infected monkeys, they had succeeded in experimentally
+infecting three healthy monkeys.
+
+The results of these experiments gained much publicity and in spite of
+the conservative manner in which they had been announced, it was widely
+proclaimed that infantile paralysis was conveyed in nature by the
+stable-fly and by it alone.
+
+Serious doubt was cast on this theory by the results of further
+experiments by Anderson and Frost, reported in May of 1913. Contrary to
+the expectations justified by their first experience, the results of all
+the later, and more extended, experiments were wholly negative. Not once
+were these investigators again able to transmit the infection of
+poliomyelitis through _Stomoxys_. They concluded that it was extremely
+doubtful that the insect was an important factor in the natural
+transmission of the disease, not only because of their series of
+negative results, "but also because recent experiments have afforded
+additional evidence of the direct transmissibility or contagiousness of
+poliomyelitis, and because epidemiological studies appear to us to
+indicate that the disease is more likely transmitted largely through
+passive human virus carriers."
+
+Soon after this, Kling and Levaditi (1913) published their detailed
+studies on acute anterior poliomyelitis. They considered that the
+experiments of Flexner and Clark (and Howard and Clark), who fed
+house-flies on emulsion of infected spinal cord, were under conditions
+so different from what could occur in nature that one could not draw
+precise conclusions from them regarding the epidemiology of the disease.
+They cited the experiments of Josefson (1912), as being under more
+reasonable conditions. He sought to determine whether the inoculation of
+monkeys with flies caught in the wards of the Hospital for Contagious
+Diseases at Stockholm, where they had been in contact with cases of
+poliomyelitis, would produce the disease. The results were completely
+negative.
+
+Kling and Lavaditi made four attempts of this kind. The flies were
+collected in places where poliomyelitics had dwelt, three, four and
+twenty-four after the beginning of the disease in the family and one,
+three, and fifteen days after the patient had left the house. These
+insects were for the greater part living and had certainly been in
+contact with the infected person. In addition, flies were used which had
+been caught in the wards of the Hospital for Contagious Diseases at
+Söderkoping, when numbers of poliomyelitics were confined there.
+Finally, to make the conditions as favorable as possible, the emulsions
+prepared from these flies were injected without previous filtering,
+since filtration often causes a weakening of the virus. In spite of
+these precautions, all their results were negative, none of the
+inoculated animals having contracted poliomyelitis. They also
+experimented with bedbugs which had fed upon infected patients at
+various stages of the disease, but the results in these cases also were
+wholly negative.
+
+Kling and Levaditi considered at length the possibility of transmission
+of the disease by _Stomoxys_. As a result of their epidemiological
+studies, they found that infantile paralysis continued to spread in
+epidemic form in the dead of winter, when these flies were very rare and
+torpid, or were even completely absent. Numerous cases developed in the
+northern part of Sweden late in October and November, long after snow
+had fallen. On account of the rarity of the Stomoxys flies during the
+period of their investigations they were unable to conduct satisfactory
+experiments. In one instance, during a severe epidemic, they found a
+number of the flies in a stable near a house inhabited by an infected
+family, though none was found in the house itself. These flies were used
+in preparing an emulsion which, after filtering, was injected into the
+peritoneal cavity of a monkey. The result was wholly negative.
+
+As for the earlier experiments, Kling and Levaditi believe if the flies
+were responsible for the transmission of the disease in the cases
+reported by Rosenau and Brues, and the first experiments of Anderson and
+Frost, it was because the virus of infantile paralysis is eliminated
+with the nasal secretions of paralyzed monkeys and the flies, becoming
+contaminated, had merely acted as accidental carriers.
+
+Still further evidence against the hypothesis of the transmission of
+acute anterior poliomyelitis by _Stomoxys calcitrans_ was brought
+forward by Sawyer and Herms (1913). Special precautions were used to
+prevent the transference of saliva or other possibly infectious material
+from the surface of one monkey to that of another, and to avoid the
+possibility of complicating the experiments by introducing other
+pathogenic organisms from wild flies, only laboratory-bred flies were
+used. In a series of seven carefully performed experiments, in which the
+conditions were varied, Sawyer and Herms were unable to transmit
+poliomyelitis from monkey to monkey through the agency of _Stomoxys_, or
+to obtain any indication that the fly is the usual agent for spreading
+the disease in nature.
+
+The evidence at hand to date indicates that acute anterior
+poliomyelitis, or infantile paralysis, is transmitted by contact with
+infected persons. Under certain conditions insects may be agents in
+spreading the disease, but their rôle is a subordinate one.
+
+
+Pellagra
+
+PELLAGRA is an endemic and epidemic disease characterized by a peculiar
+eruption or erythema of the skin (figs 144 and 145), digestive
+disturbances and nervous trouble. Insanity is a common result, rather
+than a precursor of the disease. The manifestations of pellagra are
+periodic and its duration indeterminate.
+
+[Illustration: 144. Pellagrous eruption on the face. After Watson.]
+
+The disease is one the very name of which was almost unknown in the
+United States until within the past decade. It has usually been regarded
+as tropical, though it occurs commonly in Italy and in various parts of
+Europe. Now it is known that it not only occurs quite generally in the
+United States but that it is spreading. Lavinder (1911) says that "There
+are certainly many thousand cases of the disease in this country, and
+the present situation must be looked upon with grave concern."
+
+It is not within the scope of this book to undertake a general
+discussion of pellagra. The subject is of such importance to every
+medical man that we cannot do better than refer to Lavinder's valuable
+précis. We can only touch briefly upon the entomological phases of the
+problems presented.
+
+The most commonly accepted theories regarding the etiology of the
+disease have attributed it to the use of Indian corn as an article of
+diet. This supposed relationship was explained either on the basis of,
+(a) insufficiency of nutriment and inappropriateness of corn as a prime
+article of food; (b) toxicity of corn or, (c) parasitism of certain
+organisms--fungi or bacteria--ingested with either sound or deteriorated
+corn.
+
+In 1905, Sambon proposed the theory of the protozoal origin of pellagra
+and in 1910 he marshalled an imposing array of objections to the theory
+that there existed any relationship between corn and the disease. He
+presented clear evidence that pellagra existed in Europe before the
+introduction of Indian corn from America, as an article of diet, and
+that its spread was not _pari passu_ with that of the use of corn. Cases
+were found in which the patients had apparently never used corn, though
+that is obviously difficult to establish. He showed that preventive
+measures based on the theory had been a failure. Finally, he believed
+that the recurrence of symptoms of the disease for successive springs,
+in patients who abstained absolutely from the use of corn, militated
+against the theory.
+
+[Illustration: 145. Pellagrous eruption on the hand. After Watson.]
+
+On the other hand, Sambon believed that the periodicity of the symptoms,
+peculiarities of distribution and seasonal incidence, and analogies of
+the symptoms to those of other parasitic diseases indicated that
+pellagra was of protozoal origin, and that it was insect-borne.
+
+The insect carriers, he believed to be one or more species of Simuliidæ,
+or black-flies. In support of this he stated that _Simulium_ appears to
+effect the same topographical conditions as pellagra, that in its imago
+stage it seems to present the same seasonal incidence, that it has a
+wide geographical distribution which seems to cover that of pellagra,
+and that species of the genus are known to cause severe epizootics.
+Concluding from his studies in Italy, that pellagra was limited almost
+wholly to agricultural laborers, he pointed out that the Simulium flies
+are found only in rural districts, and as a rule do not enter towns,
+villages, or houses.
+
+[Illustration: 146. A favorite breeding place of Simulium. Ithaca, N.
+Y.]
+
+When Sambon's detailed report was published in 1910, his theory was
+seized upon everywhere by workers who were anxious to test it and who,
+in most cases, were favorably disposed towards it because of the
+wonderful progress which had been made in the understanding of other
+insect-borne diseases. In this country, the entomological aspects of the
+subject have been dealt with especially by Forbes (1912), and by King
+and Jennings, under the direction of W. D. Hunter, of the Bureau of
+Entomology, and in coöperation with the Thompson-McFadden Pellagra
+Commission of the Department of Tropical Medicine of the New York
+Post-Graduate Medical School. An important series of experiments with
+monkeys has been undertaken by S. J. Hunter, of Kansas, but
+unfortunately we have as yet no satisfactory evidence that these animals
+are susceptible to the disease--a fact which renders the whole problem
+difficult.
+
+The accumulated evidence is increasingly opposed to Sambon's hypothesis
+of the transmission of pellagra by _Simulium_. This has been so clearly
+manifested in the work of the Thompson-McFadden Commission that we quote
+here from the report by Jennings (1914):
+
+"Our studies in 1912 convinced us that there was little evidence to
+support the incrimination of any species of _Simulium_ in South Carolina
+in the transmission of pellagra. Reviewing the group as a whole, we find
+that its species are essentially "wild" and lack those habits of
+intimate association with man which would be expected in the vector of
+such a disease as pellagra. Although these flies are excessively
+abundant in some parts of their range and are moderately so in
+Spartanburg County, man is merely an incidental host, and no disposition
+whatever to seek him out or to invade his domicile seems to be
+manifested. Critically considered, it is nearer the fact that usually
+man is attacked only when he invades their habitat."
+
+"As our knowledge of pellagra accumulates, it is more and more evident
+that its origin is in some way closely associated with the domicile. The
+possibility that an insect whose association with man and his immediate
+environment is, at the best, casual and desultory, can be active in the
+causation of the disease becomes increasingly remote."
+
+"Our knowledge of the biting habits of _Simulium_ is not complete, but
+it is evident, as regards American species at least, that these are
+sometimes not constant for the same species in different localities.
+Certain species will bite man freely when opportunity offers, while
+others have never been known to attack him. To assume that the proximity
+of a _Simulium_-breeding stream necessarily implies that persons in its
+vicinity must be attacked and bitten is highly fallacious. In
+Spartanburg County attacks by _Simulium_ seems to be confined to the
+immediate vicinity of the breeding-places. Our records and observations,
+exceedingly few in number, refer almost exclusively to such locations.
+Statements regarding such attacks, secured with much care and
+discrimination from a large number of persons, including many
+pellagrins, indicate conclusively that these insects are seldom a pest
+of man in this county. A certain number of the persons questioned were
+familiar with the gnats in other localities, but the majority were
+seemingly ignorant of the existence of such flies with biting habits.
+This is especially striking, in view of the fact that the average
+distance of streams from the homes of the pellagra cases studied was
+about 200 yards, many being at a distance of less than 200 yards, and
+that 78 per cent of these streams were found to be infested by larval
+_Simulium_. Such ignorance in a large number of persons cannot be
+overlooked and indicates strongly that our belief in the negligible
+character of local attacks by _Simulium_ is well founded."
+
+"In localities infested by 'sand-flies,' mosquitoes, etc., these pests
+are always well known and the ignorance described above is very
+significant."
+
+"Such positive reports as we received nearly always referred to bites
+received in the open, along streams, etc., and observations made of
+their attack were of those on field laborers in similar situations.
+Males engaged in agricultural pursuits are almost exempt from pellagra
+in Spartanburg County. During the season of 1913, in some two or three
+instances, observations were made of the biting of _Simulium_ and some
+additional and entirely creditable reports were received. These
+observations and reports were under conditions identical with those
+referred to in the reports of 1912 and confirm the conclusions based on
+the observations of that year. I would repeat with emphasis that it is
+inconceivable that a fly of the appearance and habits of the prevalent
+species of _Simulium_ could be present in such a region, especially
+about the haunts of man and attack him with sufficient frequency and
+regularity to satisfactorily account for so active and prevalent a
+disease as pellagra without being a well-known and recognized pest."
+
+"In connection with the conditions in the Piedmont region of South
+Carolina, it may be well to cite the results of a study of those in the
+arid region of western Texas."
+
+"In May, 1913, in company with Capt. J. F. Siler of the
+Thompson-McFadden Pellagra Commission, I visited the region of which
+Midland in Midland County is the center. This region is very dry and
+totally devoid of running water for a long distance in every direction.
+The only natural source of water-supply, a few water holes and ponds,
+were visited and found to be of such a nature that the survival of
+_Simulium_, far less its propagation in them, is absolutely impossible.
+The nearest stream affording possibilities as a source of _Simulium_ is
+60 miles away, while the average distance of such possibility is not
+less than 100 miles."
+
+"Artificial sources of water-supply were also investigated carefully and
+were found to offer no opportunity for the breeding of _Simulium_."
+
+"At Midland the histories of five cases of pellagra were obtained, which
+gave clear evidence that this place or its immediate vicinity was the
+point of origin. Persons of long residence in the country were
+questioned as to the occurrence of such flies as _Simulium_ and returned
+negative answers. These included a retired cattle owner, who is a man of
+education and a keen observer, an expert veterinarian stationed in the
+country who has the cattle of the country under constant observation,
+and a practical cattle man, manager of a ranch and of wide experience.
+The latter had had experience with 'Buffalo gnats' in other localities
+(in the East) and is well acquainted with them. His close personal
+supervision of the cattle under his charge, makes it practically certain
+that he would have discovered these gnats had they been present in the
+country."
+
+"At the time the study was made, _Simulium_ was breeding and active in
+the adult state in the vicinity of Dallas, Texas, in the eastern part of
+the state. We have here a region in which cases of pellagra have
+originated, yet in which _Simulium_ does not and cannot breed."
+
+Other possible insect vectors of pellagra have been studied in great
+detail and the available evidence indicates that if _any_ insect plays a
+rôle in the spread of the disease, _Stomoxys calcitrans_ most nearly
+fills the conditions. This conclusion was announced by Jennings and King
+in 1912, and has been supported by their subsequent work.
+
+Yet, after all the studies of the past decade, the old belief that
+pellagra is essentially of dietary origin is gaining ground. Goldberger,
+Waring and Willets (1914) of the United States Public Health Service
+summarize their conclusions in the statement, (1) that it is dependent
+on some yet undetermined fault in a diet in which the animal or
+leguminous protein component is disproportionately large and (2) that no
+pellagra develops in those who _consume_ a mixed, well-balanced, and
+varied diet, such, for example, as that furnished by the Government to
+the enlisted men of the Army, Navy, and Marine Corps.
+
+
+Leprosy
+
+LEPROSY is a specific, infectious disease due to _Bacillus lepræ_, and
+characterized by the formation of tubercular nodules, ulcerations, and
+disturbances of sensation. In spite of the long time that the disease
+has been known and the dread with which it is regarded, little is known
+concerning the method of transfer of the causative organism or the means
+by which it gains access to the human body.
+
+It is known that the bacilli are to be found in the tubercles, the scurf
+of the skin, nasal secretions, the sputum and, in fact in practically
+all the discharges of the leper. Under such conditions it is quite
+conceivable that they may be transferred in some instances from diseased
+to healthy individuals through the agency of insects and other
+arthropods. Many attempts have been made to demonstrate this method of
+spread of the disease, but with little success.
+
+Of the suggested insect carriers none seem to meet the conditions better
+than mosquitoes, and there are many suggestions in literature that these
+insects play an important rôle in the transmission of leprosy. The
+literature has been reviewed and important experimental evidence
+presented by Currie (1910). He found that mosquitoes feeding, under
+natural conditions, upon cases of nodular leprosy so rarely, if ever,
+imbibe the lepra bacillus that they cannot be regarded as one of the
+ordinary means of transference of this bacillus from lepers to the skin
+of healthy persons. He believes that the reason that mosquitoes that
+have fed on lepers do not contain the lepra bacillus is that when these
+insects feed they insert their proboscis directly into a blood vessel
+and thus obtain bacilli-free blood, unmixed with lymph.
+
+The same worker undertook to determine whether flies are able to
+transmit leprosy. He experimented with five species found in
+Honolulu,--_Musca domestica_, _Sarcophaga pallinervis_, _Sarcophaga
+barbata_, _Volucella obesa_ and an undetermined species of _Lucilia_.
+The experiments with _Musca domestica_ were the most detailed. From
+these experiments he concluded, first, that all of the above-named
+flies, when given an opportunity to feed upon leprous fluids, will
+contain the bacilli in their intestinal tracts and feces for several
+days after such feeding. Second, that considering the habits of these
+flies, and especially those of _Musca domestica_, it is certain that,
+given an exposed leprous ulcer, these insects will frequently convey
+immense numbers of lepra bacilli, directly or indirectly, to the skins,
+nasal mucosa, and digestive tracts of healthy persons. Additional
+evidence along this line has recently been brought forward by Honeij and
+Parker (1914), who incriminate both _Musca domestica_ and _Stomoxys
+calcitrans_. Whether or not such insect-borne bacilli are capable of
+infecting persons whose skin and mucosa are thus contaminated, Currie
+was unwilling to maintain, but he concludes that until we have more
+accurate knowledge on this point, we are justified in regarding these
+insects with grave suspicion of being one of the means of disseminating
+leprous infection.
+
+Various students of the subject have suggested that bed-bugs may be the
+carriers of leprosy and have determined the presence of acid-fast
+bacilli in the intestines of bed-bugs which had fed on leprous patients.
+Opposed to this, the careful experiments of Thompson (1913) and of
+Skelton and Parkham (1913) have been wholly negative.
+
+Borrel has recently suggested that _Demodex_, may play a rôle in
+spreading the infection in families. Many other insects and acariens
+have been suggested as possible vectors, but the experimental data are
+few and in no wise conclusive. The most that can be said is that it is
+quite possible that under favorable conditions the infection might be
+spread by any of the several blood-sucking forms or by house-flies.
+
+
+Verruga peruviana
+
+VERRUGA PERUVIANA is defined by Castellani and Chalmers as "a chronic,
+endemic, specific, general disorder of unknown origin, not contagious,
+but apparently inoculable, and characterized by an irregular fever
+associated with rheumatoid pains, anemia, followed by granulomatous
+swellings in the skin, mucous membranes, and organs of the body." It has
+been generally believed by medical men interested that the comparatively
+benign eruptive verruga is identical with the so-called Oroya, or
+Carrion's fever, a malignant type. This view is not supported by the
+work of Strong, Tyzzer and Brues, (1913).
+
+The disease is confined to South America and to definitely limited areas
+of those countries in which it does occur. It is especially prevalent in
+some parts of Peru.
+
+The causative organism and the method of transfer of verruga are
+unknown. Castellani and Chalmers pointed out in 1910 that the study of
+the distribution of the disease in Peru would impress one with the
+similarity to the distribution of the Rocky Mountain fever and would
+lead to the conclusion that the ætiological cause must in some way be
+associated with some blood-sucking animal, perhaps an arachnid, and that
+this is supported by the fact that the persons most prone to the
+infection are those who work in the fields.
+
+More recently, Townsend (1913), in a series of papers, has maintained
+that verruga and Carrion's disease are identical, and that they are
+transmitted to man by the bites of the Psychodid fly, _Phlebotomus
+verrucarum_. He succeeded in producing the eruptive type of the disease
+in experimental animals by injecting a physiological salt trituration of
+wild Phlebotomus flies. A cebus monkey was exposed from October so to
+November 6, by chaining him to a tree in the verruga zone, next to a
+stone wall from which the flies emerged in large numbers every night.
+Miliar eruption began to appear on the orbits November 13 and by
+November 21, there were a number of typical eruptions, with exudation on
+various parts of the body exactly like miliar eruptive sores commonly
+seen on legs of human cases.
+
+An assistant in the verruga work, George E. Nicholson, contracted the
+eruptive type of the disease, apparently as a result of being bitten by
+the Phlebotomus flies. He had slept in a verruga zone, under a tight
+net. During the night he evidently put his hands in contact with the
+net, for in the morning there were fifty-five unmistakable Phlebotomus
+bites on the backs of his hands and wrists.
+
+Townsend believes that in nature, lizards constitute the reservoir of
+the disease and that it is from them that the Phlebotomus flies receive
+the infection.
+
+
+Cancer
+
+There are not wanting suggestions that this dread disease is carried, or
+even caused, by arthropods. Borrel (1909) stated that he had found mites
+of the genus _Demodex_ in carcinoma of the face and of the mammæ. He
+believed that they acted as carriers of the virus.
+
+Saul (1910) and Dahl (1910) go much further, since they attribute the
+production of the malignant growth to the presence of mites which Saul
+had found in cancers. These Dahl described as belonging to a new
+species, which he designated _Tarsonemus hominis_. These findings have
+since been confirmed by several workers. Nevertheless, the presence of
+the mite is so rare that it cannot be regarded as an important factor in
+the causation of the disease. The theory that cancer is caused by an
+external parasite is given little credence by investigators in this
+field.
+
+
+IN CONCLUSION, it should be noted that the medical and entomological
+literature of the past few years abounds in suggestions, and in
+unsupported direct statements that various other diseases are
+insect-borne. Knab (1912) has well said "Since the discovery that
+certain blood-sucking insects are the secondary hosts of pathogenic
+parasites, nearly every insect that sucks blood, whether habitually or
+occasionally, has been suspected or considered a possible transmitter of
+disease. No thought seems to have been given to the conditions and the
+characteristics of the individual species of blood-sucking insects,
+which make disease transmission possible."
+
+He points out that "in order to be a potential transmitter of human
+blood-parasites, an insect must be closely associated with man and
+normally have opportunity to suck his blood repeatedly. It is not
+sufficient that occasional specimens bite man, as, for example, is the
+case with forest mosquitoes. Although a person may be bitten by a large
+number of such mosquitoes, the chances that any of these mosquitoes
+survive to develop the parasites in question, (assuming such development
+to be possible), and then find opportunity to bite and infect another
+person, are altogether too remote. Applying this criterion, not only the
+majority of mosquitoes but many other blood-sucking insects, such as
+Tabanidæ and Simuliidæ, may be confidently eliminated. Moreover, these
+insects are mostly in evidence only during a brief season, so that we
+have an additional difficulty of a very long interval during which there
+could be no propagation of the disease in question." He makes an
+exception of tick-borne diseases, where the parasites are directly
+transmitted from the tick host to its offspring and where, for this
+reason, the insect remains a potential transmitter for a very long
+period. He also cites the trypanosome diseases as possible exceptions,
+since the causative organisms apparently thrive in a number of different
+vertebrate hosts and may be transmitted from cattle, or wild animals, to
+man.
+
+Knab's article should serve a valuable end in checking irresponsible
+theorizing on the subject of insect transmission of disease.
+Nevertheless, the principles which he laid down cannot be applied to the
+cases of accidental carriage of bacterial diseases, or to those of
+direct inoculation of pyogenic organisms, or of blood parasites such as
+the bacillus of anthrax, or of bubonic plague. Accumulated evidence has
+justified the conclusion that certain trypanosomes pathogenic to man are
+harbored by wild mammals, and so form an exception. Townsend believes
+that lizards constitute the natural reservoir of verruga; and it seems
+probable that field mice harbor the organism of tsutsugamushi disease.
+Such instances are likely to accumulate as our knowledge of the relation
+of arthropods to disease broadens.
+
+
+
+
+CHAPTER XII
+
+HOMINOXIOUS ARTHROPODS
+
+
+The following synoptic tables are presented in the hope that they may be
+of service in giving the reader a perspective of the relationships of
+the Arthropoda in general and enabling him to identify the more
+important species which have been found noxious to man. Though
+applicable chiefly to the arthropods found in the United States, exotic
+genera and species which are concerned in the transmission of disease
+are also included. For this reason the keys to the genera of the Muscids
+of the world are given. As will be seen, the tables embrace a number of
+groups of species which are not injurious. This was found necessary in
+order that the student might not be lead to an erroneous determination
+which would result were he to attempt to identify a species which
+heretofore had not been considered noxious, by means of a key containing
+only the noxious forms. The names printed in BOLD FACED TYPE indicate
+the hominoxious arthropods which have been most commonly mentioned in
+literature.
+
+
+CRUSTACEA
+
+Arthropods having two pairs of antennæ which are sometimes modified for
+grasping, and usually with more than five pairs of legs. With but few
+exceptions they are aquatic creatures. Representatives are: Crabs,
+lobsters, shrimps, crayfish, water-fleas, and woodlice. To this class
+belongs the CYCLOPS (fig. 122) a genus of minute aquatic crustaceans of
+which at least one species harbors _Dracunculus medinensis_, the Guinea
+worm (fig. 121).
+
+
+MYRIAPODA
+
+Elongate, usually vermiform, wingless, terrestrial creatures having one
+pair of antennæ, legs attached to each of the many intermediate body
+segments. This group is divided into two sections, now usually given
+class rank: the DIPLOPODA or millipedes (fig. 13), commonly known as
+thousand legs, characterized by having two pairs of legs attached to
+each intermediate body segment, and the CHILOPODA or centipedes (fig.
+14) having only one pair of legs to each body segment.
+
+
+ARACHNIDA
+
+In this class the antennæ are apparently wanting, wings are never
+present, and the adults are usually provided with four pairs of legs.
+Scorpions, harvest-men, spiders, mites, etc.
+
+
+HEXAPODA (Insects)
+
+True insects have a single pair of antennæ, which is rarely vestigial,
+and usually one or two pairs of wings in the adult stage. Familiar
+examples are cockroaches, crickets, grasshoppers, bugs, dragon-flies,
+butterflies, moths, mosquitoes, flies, beetles, ants, bees and wasps.
+
+
+ORDERS OF THE ARACHNIDA
+
+a. Abdomen distinctly segmented. A group of orders including scorpions,
+    (fig. 11), whip-scorpions (fig. 10), pseudo-scorpions, solpugids
+    (fig. 12) harvest-men (daddy-long-legs or harvestmen), etc.
+    ARTHROGASTRA
+
+aa. Abdomen unsegmented, though sometimes with numerous annulations
+    SPHÆROGASTRA
+
+  b. A constriction between cephalothorax and abdomen (fig. 7). True
+      Spiders ARANEIDA
+
+  bb. No deep constriction between these parts.
+
+    c. Legs usually well developed, body more or less depressed (fig.
+        49). Mites ACARINA
+
+    cc. Legs stumpy or absent, body more or less elongate or vermiform,
+        or if shorter, the species is aquatic or semi-aquatic in habit.
+
+      d. Four pairs of short legs; species inhabiting moss or water.
+          Water-bears. TARDIGRADA
+
+      dd. Two pairs of clasping organs near the mouth, instead of legs,
+          in the adult; worm-like creatures parasitic within the nasal
+          passages, lungs, etc. of mammals and reptiles (fig. 148).
+          Tongue worms. LINGUATULINA
+
+[Illustration: 148. Linguatula. (_a_) larva; (enlarged). (_b_) adult;
+(natural size).]
+
+
+ACARINA[E]
+
+a. Abdomen annulate, elongate; very minute forms, often with but four
+    legs (fig. 62). DEMODICOIDEA
+
+  b. With but four legs of five segments each. Living on plants, often
+      forming galls. ERIOPHYIDÆ
+
+  bb. With eight legs, of three segments each. Living in the skin of
+      mammals. DEMODICIDÆ
+
+    To this family belongs the genus DEMODEX found in the sebaceous
+        glands and hair follicles of various mammals, including man. _D.
+        phylloides_ Csokor has been found in Canada on swine, causing
+        white tubercles on the skin. _D. bovis_ Stiles has been reported
+        from the United States on cattle, upon the skin of which they
+        form swellings. D. FOLLICULORUM Simon is the species found on
+        man. See page 78.
+
+aa. Abdomen not annulate nor prolonged behind; eight legs in the adult
+    stage.
+
+  b. With a distinct spiracle upon a stigmal plate on each side of the
+      body (usually ventral) above the third or fourth coxæ or a little
+      behind (fig. 50); palpi free; skin often coriaceous or leathery;
+      tarsi often with a sucker.
+
+    c. Hypostome large (fig. 50), furnished below with many recurved
+        teeth; venter with furrows, skin leathery; large forms, usually
+        parasitic. IXODOIDEA
+
+      d. Without scutum but covered by a more or less uniform leathery
+          integument; festoons absent; coxæ unarmed, tarsi without
+          ventral spurs; pulvilli absent or vestigial in the adults;
+          palpi cylindrical; sexual dimorphism slight. ARGASIDÆ
+
+        e. Body flattened, oval or rounded, with a distinct flattened
+            margin differing in structure from the general integument;
+            this margin gives the body a sharp edge which is not
+            entirely obliterated even when the tick is full fed.
+            Capitulum (in adults and nymphs) entirely invisible
+            dorsally, distant in the adult by about its own length from
+            the anterior border. Eyes absent. ARGUS Latr.
+
+          f. Body oblong; margin with quadrangular cells; anterior tibiæ
+              and metatarsi each about three times as long as broad. On
+              poultry, southwest United States. A. PERSICUS MINIATUS
+
+            _A. brevipes_ Banks, a species with proportionately shorter
+                legs has been recorded from Arizona.
+
+          ff. With another combination of characters. About six other
+              species of _Argas_ from various parts of the world,
+              parasitic on birds and mammals.
+
+        ee. Body flattened when unfed, but usually becoming very convex
+            on distention; anterior end more or less pointed and
+            hoodlike; margin thick and not clearly defined, similar in
+            structure to the rest of the integument and generally
+            disappearing on distention; capitulum subterminal, its
+            anterior portions often visible dorsally in the adult; eyes
+            present in some species.
+
+          f. Integument pitted, without rounded tubercles; body provided
+              with many short stiff bristles; eyes absent. On horses,
+              cattle and man (fig. 48). OTIOBIUS Banks.
+
+            O. MEGNINI, a widely distributed species, is the type of
+                this genus.
+
+          ff. Integument with rounded tubercles or granules; body
+              without stiff bristles. ORNITHODOROS Koch.
+
+            g. Two pairs of eyes; tarsi IV with a prominent subterminal
+                spur above; leg I strongly roughened. On cattle and man.
+                O. CORIACEUS
+
+            gg. No eyes; no such spur on the hind tarsi.
+
+              h. Tarsi I without humps above. _O. talaje._
+
+              hh. Tarsi I with humps above.
+
+                i. Tarsi IV without distinct humps above. On hogs,
+                    cattle and man. O. TURICATA
+
+                ii. Tarsi IV with humps nearly equidistant (fig. 142).
+                    Africa. O. MOUBATA
+
+[Illustration: 149. Hæmaphysalis wellingtoni. Note short palpi. After
+Nuttall and Warburton.]
+
+      dd. With scutum or shield (fig. 50); festoons usually present;
+          coxæ usually armed with spurs, tarsi generally with one or two
+          ventral spurs; pulvilli present in the adults; sexual
+          dimorphism pronounced. IXODIDÆ
+
+        e. With anal grooves surrounding anus in front; inornate;
+            without eyes; no posterior marginal festoons; venter of the
+            male with non-salient plates. Numerous species, 14 from the
+            United States, among them I. RICINUS (fig. 49 and 50),
+            SCAPULARIS, COOKEI, _hexagonus_, _bicornis_. IXODES Latr.
+            (including Ceratixodes).
+
+        ee. With anal groove contouring anus behind, or groove faint or
+            obsolete.
+
+          f. With short palpi (fig. 149).
+
+            g. Without eyes, inornate, with posterior marginal festoons;
+                male without ventral plates. Numerous species. _H.
+                chordeilis_ and _leporis-palustris_ from the United
+                States. _Hæmaphysalis_ Koch.
+
+[Illustration: 150. Stigmal plate of Dermacentor andersoni; (_a_) of
+male, (_b_) of female. After Stiles. (_c_) Dermacentor variabilis, male;
+(_d_) Glyciphagus obesus; (_e_) Otodectes cynotis; (_f_) Tyroglyphus
+lintneri; (_g_) Tarsonemus pallidus; (_h_) anal plate and mandible of
+Liponyssus; (_c_) to (_h_) after Banks.]
+
+            gg. With eyes.
+
+              h. Anal groove distinct; posterior marginal festoons
+                  present.
+
+                i. Base of the capitulum (fig. 150c) rectangular
+                    dorsally; usually ornate. DERMACENTOR Koch.
+
+                  j. Adults with four longitudinal rows of large
+                      denticles on each half of hypostome; stigmal plate
+                      nearly circular, without dorso-lateral
+                      prolongation, goblets very large, attaining 43µ to
+                      115µ in diameter; not over 40 per plate, each
+                      plate surrounded by an elevated row of regularly
+                      arranged supporting cells; white rust wanting;
+                      base of capitulum distinctly broader than long,
+                      its postero-lateral angles prolonged slightly, if
+                      at all; coxæ T with short spurs; trochanter I with
+                      small dorso-terminal blade. Texas, Arizona, etc.
+                      _D. nitens_
+
+[Illustration: 151. Rhipicephalus bursa, male. After Nuttall and
+Warburton.]
+
+                  jj. Adults with three longitudinal rows of large
+                      denticles on each half of hypostome; goblet cells
+                      always more than 40 per plate; whitish rust
+                      usually present.
+
+                    k. Dorso-lateral prolongation of stigmal plate small
+                        or absent; plates of the adults distinctly
+                        longer than broad; goblet cells large, usually
+                        30µ to 85µ in diameter, appearing as very coarse
+                        punctations on untreated specimens, but on
+                        specimens treated with caustic potash they
+                        appear very distinct in outline; base of
+                        capitulum distinctly (usually about twice)
+                        broader than long, the postero-lateral angles
+                        distinctly produced caudad; spurs of coxæ I
+                        long, lateral spur slightly longer than median;
+                        trochanter I with dorso-terminal spur. _D.
+                        albipictus_, (= _variegatus_), _salmoni_,
+                        _nigrolineatus_.
+
+                    kk. Dorso-lateral prolongation of stigmal plate
+                        distinct.
+
+                      l. Body of plate distinctly longer than broad;
+                          goblet cells of medium size, usually 17.5µ to
+                          35µ or 40µ in diameter, appearing as medium
+                          sized punctuations on untreated specimens, but
+                          on the specimens treated with caustic potash
+                          they appear very distinct in outline, which is
+                          not circular; base of capitulum usually less
+                          than twice as broad as long, the
+                          postero-lateral angles always distinctly
+                          prolonged caudad.
+
+                        m. Trochanter I with distinct dorso-subterminal
+                            retrograde sharp, digitate spur;
+                            postero-lateral angles of capitulum
+                            pronouncedly prolonged caudal, 112µ to 160µ
+                            long; goblet cells attain 13µ to 40µ in
+                            diameter; type locality California. D.
+                            OCCIDENTALIS
+
+                        mm. Trochanter I with dorso-terminal blade;
+                            postero-lateral angles of capitulum with
+                            rather short prolongations.
+
+                          n. Stigmal plate small, goblet cells not
+                              exceeding 45 in the male or 100 in the
+                              female; scutum with little rust, coxa I
+                              with short spurs, the inner distinctly
+                              shorter than the outer. _D.
+                              parumapertus-marginatus_
+
+                          nn. Stigmal plate larger; goblet cells over 70
+                              in the male and over 100 in the female;
+                              coxa I with longer spurs, inner slightly
+                              shorter than the outer; scutum with
+                              considerable rust. D. VENUSTUS[F]
+
+                      ll. Goblet cells small, rarely exceeding 17.6µ,
+                          occasionally reaching 19µ in diameter; on
+                          untreated specimens they appear as very fine
+                          granulations, and on specimens treated with
+                          caustic potash they may be difficult to see,
+                          but their large number can be determined from
+                          the prominent stems of the goblets; surface of
+                          outline of the goblets distinctly circular;
+                          base of the capitulum usually less than twice
+                          as broad as long, the postero-lateral angle
+                          distinctly prolonged caudad; spurs of coxæ I
+                          long. _D. reticulatus_ and _electus_ (=
+                          _variabilis_?)
+
+                ii. Base of the capitulum (fig. 151) usually hexagonal
+                    (except in the male of _puchellus_); and usually
+                    inornate.
+
+                  j. No ventral plate or shield in either sex (fig.
+                      153). R. BICORNIS from the United States.
+                      RHIPICENTOR Nuttall
+
+                  jj. Males with a pair of adanal shields, and usually a
+                      pair of accessory adanal shields. Numerous
+                      species, among them _R. sanguineus_ (fig. 154) and
+                      _texanus_, the latter from the United States.
+                      _Rhipicephalus_ Koch
+
+              hh. Anal grooves faint or obsolete; no marginal festoons.
+
+                i. Short palpi; highly chitinized; unfed adults of large
+                    size; coxæ conical; male with a median plate
+                    prolonged in two long spines projecting caudad;
+                    segments of leg pair IV greatly swollen (fig. 155,
+                    156). _M. winthemi_ _Margaropus_ Karsch
+
+[Illustration: 152. Monieziella (Histiogaster) emtomophaga-spermatica,
+ventral aspect, male and female. After Trouessart.]
+
+                ii. Very short palpi, ridged dorsally and laterally;
+                    slightly chitinized; unfed adults of smaller size;
+                    coxæ I bifid; male with adanal and accessory adanal
+                    shields (fig. 139). B. ANNULATUS. BOOPHILUS Curtis
+
+          ff. Palpi longer than broad (fig. 157).
+
+            g. Male with pair of adanal shields, and two posterior
+                abdominal protrusions capped by chitinized points;
+                festoons present or absent. Several species, among them
+                H. ÆGYPTICUM (fig. 140) from the old world. HYALOMMA
+                Koch
+
+            gg. Male without adanal shields but small ventral plaques
+                are occasionally present close to the festoons. Many
+                species, a few from the United States (fig. 157).
+                AMBLYOMMA Koch
+
+              h. Coxa I with but one spine; metatarsi (except I) with
+                  two thickened spurs at tips. _A. maculatum_
+
+              hh. Coxa I with two spines; metatarsi without stout spurs
+                  at tips, only slender hairs.
+
+                i. Projections of coxa I blunt and short. Large species
+                    on the gopher tortoise in Florida. _A. tuberculatum_
+
+                ii. Projections of coxa I longer, and at least one of
+                    them sharp pointed; second segment of palpus twice
+                    as long as the third; coxa IV of the male with a
+                    long spine.
+
+                  j. Porose areas nearly circular; shield of both sexes
+                      pale yellowish, with some silvery streaks and
+                      marks, and some reddish spots; shield of female as
+                      broad as long. A. CAJENNENSE (= MIXTUM).
+
+                  jj. Porose areas elongate, shield brown, in the female
+                      with an apical silvery mark, in the male with two
+                      small and two or four other silvery spots; shield
+                      of the female longer than broad (fig 158 e). A.
+                      AMERICANUM.
+
+[Illustration: 153. Rhipicentor bicornis, ventral aspect, male. After
+Nuttall and Warburton.]
+
+    cc. Hypostome small, without teeth, venter without furrows; body
+        often with coriaceous shields, posterior margin of the body
+        never crenulate (i.e. without festoons); no eyes. GAMASOIDEA.
+
+      d. Parasitic on vertebrates; mandibles fitted for piercing; body
+          sometimes constricted. DERMANYSSIDÆ.
+
+        e. Anal plate present. DERMANYSSINÆ.
+
+          f. Body short; legs stout, hind pair reaching much beyond the
+              tip of the body. On bats. _Pteroptus_ Dufour.
+
+          ff. Body long; hind legs not reaching beyond the tip of the
+              body.
+
+            g. Peritreme on the dorsum, very short; body distinctly
+                  constricted. _Ptilonyssus_ Berl.
+
+            gg. Peritreme on the venter, longer; body not distinctly
+                  constricted.
+
+                h. Mandibles in both sexes chelate. Parasitic on bats,
+                    mice and birds (fig. 150, h). LIPONYSSUS Kol.
+
+                  The species L. (= LEIOGNATHUS) SYLVIARUM frequents the
+                      nests of warblers. An instance is on record of
+                      these mites attacking man, causing a pruritis.
+
+                hh. Mandibles in the male chelate (fig. 158 j), in the
+                    female long, styliform. Parasitic on birds.
+                    DERMANYSSUS Dug. Two species of importance may be
+                    noted, _D. hirundinus_ and D. GALLINÆ. The latter
+                    (fig. 51) is a serious pest of poultry, sometimes
+                    attacking man, causing itching and soreness.
+
+        ee. Anal plate absent. In lungs and air passages of some
+            mammals. HALARACHNINÆ.
+
+      dd. Free or attached to insects, rarely on vertebrates.
+
+        e. First pair of legs inserted within the same body opening as
+            the oral tube; genital apertures surrounded by the sternum.
+            On insects. UROPODIDÆ.
+
+[Illustration: 154. Rhicephalus sanguineus, male. After Nuttall and
+Warburton.]
+
+        ee. First pair of legs inserted at one side of the mouth
+            opening; male genital aperture usually on the anterior
+            margin of the sternal plate. GAMASIDÆ.
+
+          This family contains a number of genera, some of which are
+              found upon mammals, though the majority affect only other
+              arthropods. One species, LÆLAPS STABULARIS, frequents the
+              bedding in stables, and in one instance at least, has
+              occasioned irritation and itching, in man.
+
+  bb. No distinct spiracle in the stigmal plate on each side of the
+      body.
+
+    c. Body usually coriaceous, with few hairs, with a specialized seta
+        arising from a pore near each posterior corner of the
+        cephalothorax; no eyes; mouth parts and palpi very small;
+        ventral openings of the abdomen large; tarsi without sucker. Not
+        parasitic. ORIBATOIDEA.
+
+    cc. Body softer; without such specialized seta.
+
+      d. Aquatic species. HYDRACHNOIDEA.
+
+      dd. Not aquatic.
+
+        e. Palpi small, three segmented, adhering for some distance to
+            the lip; ventral suckers at genital opening or near anal
+            opening usually present; no eyes; tarsi often end in
+            suckers; beneath the skin on the venter are seen rod-like
+            epimera that support the legs; body often entire. Adults
+            frequently parasitic. SARCOPTOIDEA.
+
+          f. With tracheæ; no ventral suckers; legs ending in claws;
+              body divided into cephalothorax and abdomen; the female
+              with a clavate hair between legs I and II. Usually not
+              parasitic on birds and mammals. TARSONEMIDÆ
+
+            g. Hind legs of female ending in claw and sucker as in the
+                other pairs. PEDICULOIDINÆ
+
+              To this sub-family belongs the genus PEDICULOIDES
+
+              P. ventricosus is described on page 69.
+
+[Illustration: 155. Margaropus winthemi, male. After Nuttall and
+Warburton.]
+
+[Illustration: 156. Margaropus winthemi, capitulum and scutum.
+After Nuttall and Warburton.]
+
+            gg. Hind legs of the female end in long hairs. TARSONEMINÆ
+
+              TARSONEMUS INTECTUS Karpelles, normally found upon grain,
+                  is said to attack man in Hungary and Russia. Other
+                  species of the genus affect various plants (c.f. fig.
+                  150, g).
+
+          ff. Without tracheæ; no such clavate hair.
+
+            g. Genital suckers usually present; integument usually
+                without fine parallel lines.
+
+              h. Legs short, without clavate hair on tarsi I and II. On
+                  insects. CANESTRINIDÆ.
+
+              hh. Legs longer, with a clavate hair on tarsi I and II.
+                  Not normally parasitic except on bees. TYROGLYPHIDÆ
+
+                i. Dorsal integument more or less granulate; claws very
+                    weak, almost invisible; some hairs of the body
+                    plainly feathered; ventral apertures large.
+                    GLYCIPHAGUS Her.
+
+                  This genus occurs in the United States. In Europe the
+                      mites have been found feeding on all sorts of
+                      substances. They are known as sugar mites and
+                      cause the disease known as grocer's itch. G.
+                      DOMESTICUS and G. PRUNORUM are old world species
+                      (fig. 150, d).
+
+                ii. Dorsal integument not granulate; claws distinct; no
+                    prominent feathered hairs; ventral aperture small.
+
+                  j. Mandibles not chelate; elongate, and toothed below;
+                      body without long hairs; palpi enlarged at tip and
+                      provided with two divergent bristles. Species feed
+                      on decaying substances. _Histiostoma_ Kram.
+
+                  jj. Mandibles chelate; palpi not enlarged at the tip,
+                      nor with two bristles.
+
+                    k. No clavate hair on the base of tarsi I and II; no
+                        suture between cephalothorax and abdomen. Live
+                        on bees or in their nests. _Trichotarsus_ Can.
+
+                    kk. A clavate or thickened hair at the base of tarsi
+                        I and II.
+
+                      l. The bristle on the penultimate segment of the
+                          legs arises from near the middle; no suture
+                          between the cephalothorax and abdomen. The
+                          species, some of which occur in the United
+                          States, feed on dried fruit, etc.
+                          _Carpoglyphus_ Robin.
+
+                      ll. The bristle on the penultimate segment of the
+                          legs arise from near the tip; a suture between
+                          cephalothorax and abdomen.
+
+                        m. Cephalothorax with four distinct and long
+                            bristles in a transverse row; tarsi I and II
+                            about twice as long as the preceding segment
+                            (fig. 150 f). TYROGLYPHUS Latr.
+
+                          n. Some bristles on tarsi I and II near
+                              middle, distinctly spine-like; the sense
+                              hair about its length from the base of the
+                              segment. Several species in the United
+                              States belong to this group.
+
+                          nn. No spine-like bristles near the middle of
+                              the tarsi; sense hair not its length from
+                              the base of the segment.
+
+                            o. Of the terminal abdominal bristles, only
+                                two are about as long as the abdomen;
+                                leg I of the male greatly thickened and
+                                with a spine at apex of the femur below.
+                                T. FARINÆ.
+
+                            oo. Of the terminal abdominal bristles at
+                                least six or more are very long, nearly
+                                as long as the body.
+
+                              p. Bristles of the body distinctly plumose
+                                  or pectinate; tarsi very long. T.
+                                  LONGIOR.
+
+                              pp. Bristles of the body not pectinate.
+
+                                q. In mills, stored foods, grains, etc.
+                                    Third and fourth joints of hind legs
+                                    scarcely twice as long as broad;
+                                    abdominal bristles not unusually
+                                    long; legs I and II of the male not
+                                    unusually stout. T. AMERICANUS.
+
+                                qq. With other characters and habits.
+                                    _T. lintneri_ (fig. 150 f) the
+                                    mushroom mite, and several other
+                                    species.
+
+                        mm. Cephalothorax with but two long distinct
+                            bristles (besides the frontal pair), but
+                            sometimes a very minute intermediate pair;
+                            tarsi I and II unusually short and not twice
+                            as long as the preceding segment.
+
+                          n. Tarsi with some stout spines. RHIZOGLYPHUS
+                              Clap.
+
+                            The species of this genus are vegetable
+                                feeders. Several occur in the United
+                                States. R. PARASITICUS and R.
+                                SPINITARSUS have been recorded from the
+                                old world, attacking human beings who
+                                handle affected plants.
+
+                          nn. Tarsi with only fine hairs. MONIEZIELLA
+                              Berl.
+
+                            The species of this genus, as far as known,
+                                are predaceous or feed on recently
+                                killed animal matter. Several species
+                                occur in the United States. M. (=
+                                HISTIOGASTER) ENTOMOPHAGA (fig. 152)
+                                from the old world has been recorded as
+                                injurious to man.
+
+            gg. Genital suckers absent; integument with fine parallel
+                lines. Parasitic on birds and mammals.
+
+              h. Possessing a specially developed apparatus for clinging
+                  to hairs of mammals. LISTROPHORIDÆ.
+
+              hh. Without such apparatus.
+
+                i. Living on the plumage of birds. ANALGESIDÆ.
+
+                ii. In the living tissues of birds and mammals.
+
+                  j. Vulva longitudinal. In the skin and cellular
+                      tissues of birds. CYTOLEICHIDÆ.
+
+                    This family contains two species, both occurring in
+                        the United States on the common fowl.
+                        _Laminosioptes cysticola_ occurs on the skin and
+                        also bores into the subcutaneous tissue where it
+                        gives rise to a calcareous cyst. _Cytoleichus
+                        nudus_ is most commonly found in the air
+                        passages and air cells.
+
+                  jj. Vulva transverse. In the skin of mammals and
+                      birds. SARCOPTIDÆ
+
+                    k. Anal opening on the dorsum.
+
+                      l. Third pair of legs in the male without apical
+                          suckers. On cats and rabbits. NOTOEDRES
+                          Rail.
+
+                        The itch mite of the cat, N. CATI (fig. 61) has
+                            been recorded on man.
+
+                      ll. Third leg in the male with suckers. On bats
+                          _Prosopodectes_ Can.
+
+                    kk. Anal opening below.
+
+                      l. Pedicel of the suckers jointed; mandibles
+                          styliform and serrate near the tip. PSOROPTES
+                          Gerv. P. COMMUNIS OVIS is the cause of sheep
+                          scab.
+
+                      ll. Pedicel of the suckers not jointed; mandibles
+                          chelate.
+
+                        m. No suckers on the legs of the females;
+                            parasitic on birds, including chickens. _C.
+                            mutans_ is itch mite of chickens.
+                            _Cnemidocoptes_ Fürst.
+
+                        mm. Suckers at least on legs I and II; parasitic
+                            on mammals.
+
+                          n. Legs very short; in the male the hind pairs
+                              equal in size; body usually short.
+                              SARCOPTES Latr.
+
+                            S. SCABIEI is the itch mite of man (fig.
+                                56).
+
+[Illustration: 157. Amblyomma, female. After Nuttall and Warburton.]
+
+                          nn. Legs more slender; in the male the third
+                              pair is much larger than the fourth; body
+                              more elongate.
+
+                            o. Female with suckers on the fourth pair of
+                                legs. Species do not burrow in the skin,
+                                but produce a scab similar to sheep
+                                scab. They occur in the ox, horse, sheep
+                                and goat. CHORIOPTES Gerv. C. SYMBIOTES
+                                BOVIS of the ox has been recorded a few
+                                times on man.
+
+                            oo. Female without suckers to the fourth
+                                legs.
+
+                              p. Hind part of the male abdomen with two
+                                  lobes. On a few wild animals.
+                                  _Caparinia_ Can.
+
+                              pp. Hind part of the male abdomen without
+                                  lobes. Live in ears of dogs and cats.
+                                  _Otodectes_ Canestr.
+
+                                _O. cynotis_ Hering (fig. 150 e) has
+                                    been taken in the United States.
+
+        ee. Palpi usually of four or five segments, free; rarely with
+            ventral suckers near genital or anal openings; eyes often
+            present; tarsi never end in suckers; body usually divided
+            into cephalothorax and abdomen; rod-like epimera rarely
+            visible; adults rarely parasitic.
+
+          f. Last segment of the palpi never forms a thumb to the
+              preceding segment; palpi simple, or rarely formed to hold
+              prey; body with but few hairs. EUPODOIDEA.
+
+            g. Palpi often geniculate, or else fitted for grasping prey;
+                mandibles large and snout like; cephalothorax with four
+                long bristles above, two in front, two behind; last
+                segment of leg I longer than the preceding segment,
+                often twice as long. BDELLIDÆ.
+
+            gg. Palpi never geniculate (fig. 158a), nor fitted for
+                grasping prey: beak small; cephalothorax with bristles
+                in different arrangement; last segment of leg I shorter
+                or but little longer than the preceding joint; eyes when
+                present near posterior border. EUPODIDÆ
+
+              Moniez has described a species from Belgium (TYDEUS
+                  MOLESTUS) which attacks man. It is rose colored;
+                  eyeless; its legs are scarcely as long as its body,
+                  the hind femur is not thickened; the mandibles are
+                  small and the anal opening is on the venter. The
+                  female attains a length of about 0.3 mm.
+
+          ff. Last segment of the palpus forms a thumb to the preceding,
+              which ends in a claw (with few exceptions); body often
+              with many hairs (fig. 158 k). TROMBIDOIDEA.
+
+            g. Legs I and II with processes bearing spines; skin with
+                several shields; coxæ contiguous. CÆCULIDÆ.
+
+            gg. Legs I and II without such processes; few if any
+                shields.
+
+              h. Palpi much thickened on the base, moving laterally,
+                  last joint often with two pectinate bristles; no eyes;
+                  legs I ending in several long hairs; adult sometimes
+                  parasitic. CHEYLETIDÆ
+
+                CHEYLETUS ERUDITUS, which frequents old books, has once
+                    been found in pus discharged from the ear of man.
+
+              hh. Palpi less thickened, moving vertically; eyes usually
+                  present; leg I not ending in long hairs.
+
+                i. Coxæ contiguous, radiate; legs slender, bristly; body
+                    with few hairs; no dorsal groove; tarsi not swollen.
+                    ERYTHRÆIDÆ.
+
+                ii. Coxæ more or less in two groups; legs less bristly.
+
+[Illustration: 158. (_a_) Tydeus, beak and leg from below; (_b_)
+Cheyletus pyriformis, beak and palpus; (_c_) beak and claw of
+Pediculoides; (_d_) leg of Sarcoptes; (_e_) scutum of female of
+Amblyomma americana; (_f_) leg I and tip of mandible of Histiostoma
+americana; (_g_) Histiogaster malus, mandible and venter; (_h_)
+Aleurobius farinæ, palpus and leg I of male; (_i_) Otodectes cynotis, tip of
+abdomen of male, (_j_) beak and anal plate of Dermanyssus gallinæ female; (_k_)
+palpus of Allothrombium. (_a_) to (_j_) after Banks.]
+
+                  j. Body with fewer, longer hairs; often spinning
+                      threads; no dorsal groove; tarsi never swollen;
+                      mandibles styliform (for piercing). TETRANYCHIDÆ
+
+                    The genus TETRANYCHUS may be distinguished from the
+                        other genera occurring in the United States by
+                        the following characters: No scale-like
+                        projections on the front of the cephalothorax;
+                        legs I as long or longer than the body; palp
+                        ends in a distinct thumb; the body is about 1.5
+                        times as long as broad. T. MOLESTISSIMUS Weyenb.
+                        from South America, and T. TELARIUS from Europe
+                        and America ordinarily infesting plants, are
+                        said also to molest man.
+
+                  jj. Body with many fine hairs or short spines; not
+                      spinning threads; often with dorsal groove; tarsi
+                      often swollen.
+
+                    k. Mandibles styliform for piercing. RHYCHOLOPHIDÆ.
+
+                    kk. Mandibles chelate, for biting. TROMBIDIDÆ
+
+                      The genus TROMBIDIUM has recently been subdivided
+                          by Berlese into a number of smaller ones, of
+                          which some five or six occur in the United
+                          States. The mature mite is not parasitic but
+                          the larvæ which are very numerous in certain
+                          localities will cause intense itching,
+                          soreness, and even more serious complications.
+                          They burrow beneath the skin and produce
+                          inflamed spots. They have received the
+                          popular name of "RED BUG." The names LEPTUS
+                          AMERICANUS and L. IRRITANS have been applied
+                          to them, although they are now known to be
+                          immature stages. (Fig. 44.)
+
+
+HEXAPODA (Insecta)
+
+The Thysanura (springtails and bristletails), the Neuropteroids
+(may-flies, stone-flies, dragon-flies, caddis-flies, etc.), Mallophaga
+(bird lice), Physopoda (thrips), Orthoptera (grasshoppers, crickets,
+roaches), are of no special interest from our viewpoint. The remaining
+orders are briefly characterized below.
+
+
+SIPHUNCULATA (page 275)
+
+Mouth parts suctorial; beak fleshy, not jointed; insect wingless;
+parasitic upon mammals. Metamorphosis incomplete. Lice.
+
+
+HEMIPTERA (page 275)
+
+Mouth parts suctorial; beak or the sheath of the beak jointed; in the
+mature state usually with four wings. In external appearance the
+immature insect resembles the adult except that the immature form (i.e.
+nymph) never has wings, the successive instars during the process of
+growth, therefore, are quite similar; and the metamorphosis is thus
+incomplete. To this order belong the true bugs, the plant lice, leaf
+hoppers, frog hoppers, cicadas, etc.
+
+
+LEPIDOPTERA
+
+The adult insect has the body covered with scales and (with the rare
+exception of the females of a few species) with four wings also covered
+with scales. Proboscis, when present, coiled, not segmented, adapted for
+sucking. Metamorphosis complete, i.e. the young which hatches from the
+egg is quite unlike the adult, and after undergoing several molts
+transforms into a quiescent pupa which is frequently enclosed in a
+cocoon from which the adult later emerges. The larvæ are known as
+caterpillars. Butterflies and moths.
+
+
+DIPTERA (page 285)
+
+The adult insect is provided with two, usually transparent, wings, the
+second pair of wings of other insects being replaced by a pair of
+halteres or balancers. In a few rare species the wings, or halteres, or
+both, are wanting. The mouth parts, which are not segmented, are adapted
+for sucking. The tarsi are five-segmented. Metamorphosis complete. The
+larvæ, which are never provided with jointed legs, are variously known
+as maggots, or grubs, or wrigglers. Flies, midges, mosquitoes.
+
+
+SIPHONAPTERA (page 316)
+
+Mouth parts adapted for sucking; body naked or with bristles and spines;
+prothorax well developed; body compressed; tarsi with five segments;
+wings absent. Metamorphosis complete. The larva is a wormlike creature.
+Fleas.
+
+
+COLEOPTERA
+
+Adult with four wings (rarely wanting), the first pair horny or
+leathery, veinless, forming wing covers which meet in a line along the
+middle of the back. Mouth parts of both immature stages and adults
+adapted for biting and chewing. Metamorphosis complete. The larvæ of
+many species are known as grubs. Beetles.
+
+
+HYMENOPTERA
+
+Adult insect with four, usually transparent, wings, wanting in some
+species. Mouth parts adapted for biting and sucking; palpi small; tarsi
+four or five-segmented. Metamorphosis complete. Parasitic four-winged
+flies, ants, bees, and wasps.
+
+
+SIPHUNCULATA AND HEMIPTERA
+
+a. Legs with claws fitted for clinging to hairs; wings wanting;
+    spiracles of the abdomen on the dorsal surface. (= ANOPLURA =
+    PARASITICA) SIPHUNCULATA.
+
+  b. Legs not modified into clinging hooks; tibia and tarsus very long
+      and slender; tibia without thumb-like process; antennæ
+      five-segmented HÆMATOMYZIDÆ Endr.
+
+    _Hæmatomyzus elephantis_ on the elephant.
+
+  bb. Legs modified into clinging hooks; tibia and tarsus usually short
+      and stout; tibia with a thumb-like process; head not anteriorly
+      prolonged, tube-like.
+
+    c. Body depressed; a pair of stigmata on the mesothorax, and
+        abdominal segments three to eight; antennæ three to
+        five-segmented.
+
+      d. Eyes large, projecting, distinctly pigmented; pharynx short and
+          broad; fulturæ (inner skeleton of head) very strong and broad,
+          with broad arms; proboscis short, scarcely attaining the
+          thorax. PEDICULIDÆ
+
+        e. Antennæ three-segmented. A few species occurring upon old
+            world monkeys. _Pedicinis_ Gerv.
+
+        ee. Antennæ five-segmented.
+
+          f. All legs stout; thumb-like process of the tibia very long
+              and slender, beset with strong spines, fore legs stouter
+              than the others; abdomen elongate, segments without
+              lateral processes; the divided telson with a conical
+              process posteriorly upon the ventral side. PEDICULUS L.
+
+            g. Upon man.
+
+              h. Each abdominal segment dorsally with from one to three
+                  more or less regular transverse rows of small setæ;
+                  antenna about as long as the width of the head. Head
+                  louse (fig. 65). P. HUMANUS.
+
+              hh. "No transverse rows of abdominal setæ; antenna longer
+                  than the width of the head; species larger." Piaget.
+                  Body louse of man. P. CORPORIS.
+
+            gg. Upon apes and other mammals. _P. pusitatus_ (?).
+
+          ff. Fore legs delicate, with very long and slender claws;
+              other legs very stout with short and stout claws;
+              thumb-like process of the tibia short and stout; abdomen
+              very short and broad; segment one to five closely crowded,
+              thus the stigmata of segments three to five apparently
+              lying in one segment; segments five to eight with lateral
+              processes; telson without lateral conical appendages (fig.
+              69). Crab louse of man. PHTHIRUS PUBIS.
+
+      dd. Eyes indistinct or wanting; pharynx long and slender, fulturæ
+          very slender and closely applied to the pharynx; proboscis
+          very long. Several genera found upon various mammals.
+          HÆMATOPINIDÆ.
+
+    cc. Body swollen; meso- and metathorax, and abdominal segments two
+        to eight each with a pair of stigmata; eyes wanting; antennæ
+        four or five-segmented; body covered with stout spines. Three
+        genera found upon marine mammals. ECHINOPHTHIRIIDÆ
+
+aa. Legs fitted for walking or jumping; spiracles of abdomen usually
+    ventral; beak segmented.
+
+  b. Apex of head usually directed anteriorly; beak arising from its
+      apex; sides of the face remote from the front coxæ; first pair of
+      wings when present thickened at base, with thinner margins.
+      HETEROPTERA
+
+[Illustration: 159. Taxonomic details of Hemiptera-Heteroptera. (_a_)
+Dorsal aspect; (_b_) seta from bedbug; (_c_) wing of Heteropteron; (_d_)
+leg; (_e_) wing of Sinea.]
+
+    c. Front tarsi of one segment, spade-form (palæformes); beak short,
+        at most two-segmented; intermediate legs long, slender;
+        posterior pair adapted for swimming. CORIXIDÆ
+
+    cc. Front tarsi rarely one-segmented, never spade-form; beak free,
+        at least three-segmented.
+
+      d. Pulvilli wanting.
+
+        e. Hemelytra usually with a distinct clavus (fig. 159), clavus
+            always ends behind the apex of the scutellum, forming the
+            commissure. (Species having the wings much reduced or
+            wanting should be sought for in both sections.)
+
+          f. Antennæ very short; meso- and metasternum composite; eyes
+              always present.
+
+            g. Ocelli present; beak four-segmented. OCHTERIDÆ and
+                NERTHRIDÆ.
+
+            gg. Ocelli wanting; antennæ more or less hidden in a groove.
+
+              h. Anterior coxæ inserted at or near anterior margin of
+                  the prosternum; front legs raptorial; beak
+                  three-segmented BELOSTOMIDÆ (with swimming legs),
+                  NEPIDÆ, NAUCORIDÆ.
+
+                i. Metasternum without a median longitudinal keel;
+                    antennæ always four-segmented.
+
+                  j. Beak short, robust, conical; the hairy fleck on the
+                      corium elongate, large, lying in the middle
+                      between the inner angle of the membrane and the
+                      outer vein parallel to the membrane margin;
+                      membrane margin S-shaped.
+
+                    k. The thick fore femur with a relatively deep
+                        longitudinal furrow to receive the tibia.
+                        Several American species (fig. 19f.). BELOSTOMA
+                        (= Lethocerus Mayer)
+
+                    kk. The less thickened fore femur without such a
+                        furrow. B. GRISEUS. BENACUS Stäl.
+
+                  jj. Beak slender, cylindrical; the hairy spot on the
+                      corium rounded lying next to the inner angle of
+                      the membrane.
+
+                    k. Membrane large, furrow of the embolium broadened.
+                        _Z. aurantiacum_, _fluminea_, etc. _Zaitha_
+
+                    kk. Membrane very short; furrow of embolium not
+                        broadened. Western genus. _Pedinocoris_
+
+              ii. Metasternum with a long median longitudinal keel.
+                  Southwestern forms. _Abedus ovatus_ and _Deniostoma
+                  dilatato_
+
+            hh. Anterior coxæ inserted at the posterior margin of the
+                prosternum; legs natatorial. Back swimmers (fig. 19 b.).
+                NOTONECTIDÆ
+
+              i. Apices of the hemelytra entire; the three pairs of legs
+                  similar in shape; beak three-segmented; abdomen not
+                  keeled or hairy. _Plea_ Leach
+
+              ii. Apices of hemelytra notched; legs dissimilar; beak
+                  four-segmented; abdomen keeled and hairy.
+
+                j. Hemelytra usually much longer than the abdomen;
+                    fourth segment of the antenna longer than the third
+                    segment; hind tarsi with claws. _Bueno_ Kirk.
+
+                jj. Hemelytra but little longer than the abdomen; fourth
+                    segment of the antenna shorter than the third
+                    segment; hind tarsi without claws (fig. 19b).
+                    NOTONECTA L.
+
+          ff. Antennæ longer than the head; or if shorter, then the eyes
+              and ocelli absent.
+
+            g. Eyes, ocelli, and scutellum wanting; beak
+                three-segmented; head short; hemelytra always short;
+                membrane wanting. Insects parasitic on bats. POLYCTENIDÆ
+
+            gg. Eyes present.
+
+              h. First two antennal segments very short, last two long,
+                  pilose, third thickened at the base; ocelli present,
+                  veins of the hemelytra forming cells. DIPSOCORIDÆ (=
+                  CERATOCOMBIDÆ) including SCHIZOPTERIDÆ.
+
+              hh. Third segment of the antenna not thickened at the
+                  base, second as long or longer than the third, rarely
+                  shorter.
+
+                i. Posterior coxæ hinged (cardinate), if rarely
+                    rotating, the cuneus is severed, the membrane is one
+                    or two-celled, and the meso- and metasternum are
+                    composite.
+
+                  j. Ocelli absent, clypeus dilated toward the apex;
+                      hemelytra always short, membrane wanting. Species
+                      parasitic. Bed bugs, etc. CIMICIDÆ
+
+                    k. Beak short, reaching to about the anterior coxæ;
+                        scutellum acuminate at the apex; lateral margin
+                        of the elytra but little reflexed, apical margin
+                        more or less rounded; intermediate and posterior
+                        coxæ very remote.
+
+                      l. Body covered with short hairs, only the sides
+                          of the pronotum and the hemelytra fringed with
+                          longer hairs; antennæ with the third and
+                          fourth segments very much more slender than
+                          the first and second; pronotum with the
+                          anterior margin very _deeply sinuate_. CIMEX
+                          L.
+
+                        m. Sides of the pronotum widely dilated, broader
+                            than the breadth of one eye, and densely
+                            fringed with backward curved hairs; apical
+                            margin of the hemelytra nearly straight,
+                            rounded toward the interior or exterior
+                            angles.
+
+                          n. Body covered with very short hairs; second
+                              segment of the antenna shorter than the
+                              third; sides of the pronotum feebly
+                              reflexed, fringed with shorter hairs than
+                              the breadth of one eye; hemelytra with the
+                              commissural (inner) margin rounded and
+                              shorter than the scutellum, apical margin
+                              rounded towards the interior angle. The
+                              common bed bug (fig. 19h). C. LECTULARIUS
+                              Linn
+
+                          nn. Body covered with longer hairs; second and
+                              third segments of the antenna of equal
+                              length; side of the pronotum narrowly, but
+                              distinctly, reflexed, fringed with longer
+                              hairs than the breadth of one eye;
+                              hemelytra with the commissural margin
+                              straight and longer than the scutellum,
+                              apical margin rounded towards the exterior
+                              angle. Species found on bats in various
+                              parts of the United States. _C.
+                              pillosellus_ Hov.
+
+                        mm. Sides of the pronotum neither dilated, nor
+                            reflexed, fringed with less dense and nearly
+                            straight hairs; hemelytra with the apical
+                            margin distinctly rounded. Parasitic on man,
+                            birds and bats. Occurs in the old world,
+                            Brazil and the West Indies. C. HEMIPTERUS
+                            Fabr. (= rotundatus)
+
+                      ll. Body clothed with rather longer silky hairs;
+                          third and fourth segments of the antenna
+                          somewhat more slender than the first and
+                          second; anterior margin of the pronotum _very
+                          slightly sinuate_ or nearly straight in the
+                          middle, produced at the lateral angles. This
+                          is the species which in American collections
+                          is known as _C. hirundinis_, the latter being
+                          an old world form. It is found in swallows
+                          nests. O. VICARIUS. OECIACUS Stäl
+
+                    kk. Beak long, reaching to the posterior coxæ;
+                        scutellum rounded at the apex; lateral margins
+                        of the elytra strongly reflexed, apical margin
+                        slightly sinuate toward the middle; intermediate
+                        and posterior coxæ sub-contiguous. This species
+                        infests poultry in southwest United States and
+                        in Mexico. H. INODORUS. HÆMATOSIPHON Champ.
+
+[Illustration: 160. Pselliopsis (Milyas) cinctus (×2). After C. V.
+Riley.]
+
+                  jj. Ocelli present, if rarely absent in the female,
+                      then the tarsus has two segments; or if with three
+                      tarsal segments, the wing membrane with one or two
+                      cells.
+
+                    k. Beak four-segmented, or with two-segmented tarsi.
+                        ISOMETOPIDÆ, MICROPHYSIDÆ, and some CAPSIDÆ.
+
+                    kk. Beak three-segmented.
+
+                      l. Hemelytra with embolium; head horizontal, more
+                          or less conical; membrane with one to four
+                          veins, rarely wanting. ANTHOCORIDÆ
+
+                        Several species of this family affecting man
+                            have been noted, ANTHOCORIS KINGI and
+                            CONGOLENSE, from Africa and LYCTOCORIS
+                            CAMPESTRIS from various parts of the world.
+                            LYCTOCORIS FITCHII Reuter (fig. 19 j), later
+                            considered by Reuter as a variety of L.
+                            CAMPESTRIS, occurs in the United States.
+
+                      ll. Hemelytra without embolium. Superfamily
+                          ACANTHIOIDEA (= SALDÆ Fieber and LEPTOPODÆ
+                          Fieber)
+
+                ii. Posterior coxæ rotating.
+
+                  j. Claws preapical; aquatic forms. GERRIDÆ and VELIADÆ
+
+                  jj. Claws apical.
+
+                    k. Prosternum without stridulatory sulcus (notch for
+                        beak).
+
+                      l. Tarsus with three segments; membrane with two
+                          or three longitudinal cells from which veins
+                          radiate; rarely with free longitudinal veins
+                          (Arachnocoris) or veins nearly obsolete
+                          (Arbela); clavus and corium coriaceous; ocelli
+                          rarely absent. NABIDÆ
+
+                        REDUVIOLUS (= CORISCUS) SUBCOLEOPTRATUS (fig. 19
+                            g), a species belonging to this family,
+                            occurring in the United States, has been
+                            accused of biting man. This insect is flat,
+                            of a jet black color, bordered with yellow
+                            on the sides of the abdomen, and with
+                            yellowish legs. It is predaceous, feeding on
+                            other insects.
+
+                      ll. With other combinations of characters.
+                          HYDROMETRIDÆ, HENICOCEPHALIDÆ, NÆOGEIDÆ,
+                          MESOVELIADÆ, JOPPEICIDÆ
+
+                    kk. Prosternum with stridulatory sulcus (notch for
+                        beak); with three segments, short, strong.
+
+                      l. Antennæ filiform or sometimes more slender
+                          apically, geniculate; wing membrane with two
+                          or three large basal cells; scutellum small or
+                          moderate REDUVIIDÆ
+
+                        For a key to the genera and species see next
+                            page.
+
+                      ll. Last antennal segment clavate or fusiform; win
+                          membrane with the veins often forked and
+                          anastomosing; scutellum large; tarsi each with
+                          two segments; fore legs strong. (= PHYMATIDÆ)
+                          MACROCEPHALIDÆ
+
+        ee. Clavus noticeably narrowed towards the apex, never extending
+            beyond the scutellum, the two not meeting to form a
+            commissure; head horizontal, much prolonged between the
+            antennæ, on each side with an antennal tubercle, sometimes
+            acute; ocelli absent; meso- and metasternum simple; tarsi
+            each with two segments; body flattened (fig. 19c). ARADIDÆ,
+            including DYSODIIDÆ.
+
+      dd. Pulvilli present (absent in one Australian family
+          THAUMATOCORIDÆ in which case there is a membranous appendage
+          at the tip of the tibia). CAPSIDÆ (= MIRIDÆ),[G] _Eotrechus_
+          (in family GERRIDÆ), NÆOGAIDÆ, TINGITIDÆ, PIESMIDÆ,
+          MYODOCHIDÆ, CORIZIDÆ, COREIDÆ, ALYDIDÆ, PENTATOMIDÆ,
+          SCUTELLERIDÆ, etc.
+
+  bb. Apex of head directed ventrally, beak arising from the hinder part
+      of the lower side of the head; sides of face contiguous to the
+      front coxæ; first pair of wings, when present, of uniform
+      thickness. Cicadas, scale insects, plant lice (Aphids),
+      spittle-insects, leaf hoppers, etc. HOMOPTERA
+
+
+REDUVIIDÆ OF THE UNITED STATES
+
+(Adapted from a key given by Fracker).
+
+a. Ocelli none; wings and hemelytra always present in the adults; no
+    discoidal areole in the corium near the apex of the clavus.
+    _Orthometrops decorata_, _Oncerotrachelus acuminatus_, etc.,
+    Pennsylvania and south. _Sarcinæ_
+
+aa. Ocelli present in the winged individuals; anterior coxæ not as long
+    as the femora.
+
+  b. Hemelytra without a quadrangular or discoidal areole in the corium
+      near the apex of the clavus.
+
+    c. Ocelli not farther cephalad than the caudal margins of the eyes;
+        segment two of the antenna single.
+
+      d. Thorax usually constricted caudad of the middle; anterior coxæ
+          externally flat or concave. PIRATINÆ
+
+        e. Middle tibiæ without spongy fossa, head long, no lateral
+            tubercle on neck. _S. stria_, Carolina, Ill., Cal.
+            _Sirthenia_ Spinola
+
+        ee. Middle tibiæ with spongy fossa; fore tibiæ convex above;
+            neck with a small tubercle on each side.
+
+          f. Apical portion of anterior tibiæ angularly dilated beneath,
+              the spongy fossa being preceded by a small prominence.
+              MELANOLESTES Stäl
+
+            g. Black, with piceous legs and antennæ. N. E. States (fig.
+                19a) M. PICIPES
+
+            gg. Sides, and sometimes the whole dorsal surface of the
+                abdomen red. Ill., and southward. M. ABDOMINALIS
+
+          ff. Tibiæ not dilated as in "f"; spongy fossa elongate;
+              metapleural sulci close to the margin. R. BIGUTTATUS (fig.
+              22). South RASAHUS A. and S.
+
+      dd. Thorax constricted in the middle or cephalad of the middle;
+          anterior tarsi each three-segmented.
+
+        e. Apex of the scutellum narrow, without spines or with a single
+            spine REDUVIINÆ
+
+          f. Antennæ inserted in the lateral or dorso-lateral margins of
+              the head; antenniferous tubercles slightly projecting from
+              the sides of the head; head produced strongly cephalad;
+              ocelli at least as far apart as the eyes.
+
+            g. Antennæ inserted very near the apex of the head; segments
+                one and three of the beak short, segment two nearly four
+                times as long as segment one. R. PROLIXUS. W. I.
+                RHODNIUS Stäl
+
+            gg. Antennæ inserted remote from the vertex of the head.
+
+              h. Body slightly hairy; pronotum distinctly constricted;
+                  angles distinct; anterior lobe four-tuberculate, with
+                  the middle tubercles large and conical. _M.
+                  phyllosoma_, large species from the southwest.
+                  _Meccus_ Stäl
+
+              hh. Body smooth, margin of the pronotum sinuous, scarcely
+                  constricted; anterior lobe lined with little
+                  tubercles. CONORHINUS Lap.
+
+                i. Surface of the pronotum and prosternum more or less
+                    granular.
+
+                  j. Eyes small, head black; body very narrow, a fifth
+                      as wide as long; beak reaches the middle of the
+                      prosternum. California. C. PROTRACTUS
+
+                  jj. Eyes large, head fuscous; body at least a fourth
+                      as wide as long. Southern species. _C.
+                      rubrofasciatus_
+
+                ii. Pronotum and prosternum destitute of granules.
+
+                  j. Border of abdomen entirely black except for a
+                      narrow yellowish spot at the apex of one segment.
+                      Texas. _C. gerstaeckeri_
+
+                  jj. Border of abdomen otherwise marked.
+
+                    k. Beak slender, joints one and two slightly pilose,
+                        two more than twice as long as one; tubercles at
+                        the apical angles of the pronotum slightly
+                        acute, conical. Md. to Ill. and south. The
+                        masked bed bug hunter (fig. 71). C. SANGUISUGUS
+
+                    kk. Beak entirely pilose, joint two a third longer
+                        than joint one; joint one much longer than
+                        three; tubercles at the apical angles of
+                        pronotum slightly elevated, obtuse. Ga., Ill.,
+                        Tex., Cal. _C. variegatus_
+
+          ff. Antenna inserted on top of the head between margins, close
+              to the eyes; antenniferous tubercles not projecting from
+              the side of the head.
+
+            g. Anterior lobe of the pronotum with a bispinous or
+                bituberculate disc; femora unarmed. _S. arizonica_, _S.
+                bicolor_. Southwestern species. _Spiniger_ Burm.
+
+            gg. Disc of pronotum unarmed; apex of scutellum produced
+                into a spine; ocelli close to the eyes; eyes large and
+                close together. REDUVIUS Lamarck
+
+              h. Color piceous. Widely distributed in the United States.
+                  (Fig. 20). R. PERSONATUS
+
+              hh. More or less testaceous in color. Southwestern states.
+                  R. SENILIS
+
+        ee. Apex of scutellum broad, with two or three spines.
+            ECTRICHODIINÆ
+
+          f. First segment of the antenna about as long as the head. _E.
+              cruciata_ Pa. and south; _E. cinctiventris_, Tex. and Mex.
+              _Ectrichodia_ L. et S.
+
+          ff. First segment of the antennæ short. _P. æneo-nitens_.
+              South. _Pothea_ A. et S.
+
+    cc. Ocelli cephalad of the hind margins of the eyes; first segment
+        of the antennæ stout, second segment divided into many smaller
+        segments. South and west. _Homalocoris maculicollis_, and
+        _Hammatocerus purcis_. HAMMATOCERINÆ
+
+  bb. Hemelytra with a quadrangular or discoidal areole in the corium
+      near the apex of the clavus (fig. 159e).
+
+    c. Anal areole of the membrane not extending as far proximad as the
+        costal areole; basal segment of the antenna thickened, porrect;
+        the other segments slender, folding back beneath the head and
+        the first segment STENOPODINÆ
+
+      d. Head armed with a ramous or furcate spine below each side,
+          caudad of the eyes.
+
+        e. First segment of the antenna thickened, apex produced in a
+            spine beyond the insertion of the second segment. Species
+            from Va., Ill. and south. _Pnirontis_ Stäl.
+
+        ee. First segment of the antenna not produced beyond the
+            insertion of the second segment. _Pygolampis_, N. E. states
+            and south; _Gnathobleda_, S. W. and Mex.
+
+      dd. Head unarmed below or armed with a simple spine; rarely with a
+          subfurcate spine at the side of the base. Carolina, Missouri
+          and south. _Stenopoda_, _Schumannia_, _Diaditus_, _Narvesus_,
+          _Oncocephalus_
+
+    cc. Anal areole of membrane extending farther proximad than the
+        costal areole.
+
+      d. Ocelli farther apart than the eyes. _A. crassipes_, widely
+          distributed in the United States; other species occur in the
+          southwest. _Apiomerus_ Hahn.
+
+      dd. Ocelli not so far apart as the eyes. ZELINÆ
+
+        e. Sides of mesosternum without a tubercle or fold in front.
+
+          f. Fore femur as long as or longer than the hind femur; first
+              segment of the beak much shorter than the second. _Z.
+              audax_, in the north eastern states; other species south
+              and west. _Zelus_ Fabr.
+
+          ff. Fore femur shorter than the hind femur, rarely of equal
+              length, in this case the first segment of the beak as long
+              or longer than the second.
+
+            g. First segment of the beak shorter than the second; fore
+                femur a little shorter than the hind femur; the first
+                segment of the beak distinctly longer than the head
+                before the eyes. _P. cinctus_ a widely distributed
+                species (fig. 160). _P. punctipes_, _P. spinicollis_,
+                Cal., Mex. (= _Milyas_) _Pselliopus_ Berg.
+
+            gg. First segment of the beak as long or longer than the
+                second.
+
+              h. Pronotum armed with spines on the disc.
+
+                i. Juga distinctly prominent at the apex and often acute
+                    or subacute; fore femur distinctly thickened;
+                    hemelytra usually not reaching the apex of the
+                    abdomen. _Fitchia aptera_, N. Y., south and west;
+                    _F. spinosula_, South; _Rocconata annulicornis_,
+                    Texas, etc.
+
+                ii. Juga when prominent, obtuse at apex; eyes full width
+                    of the head; fore femur not thickened; pronotum with
+                    four spines on posterior lobe. _R. taurus_, Pa.,
+                    south and west. _Repipta_ Stäl.
+
+              hh. Pronotum unarmed on the disc.
+
+                i. Spines on each apical angle of the penultimate
+                    abdominal segment. _A. cinereus_, Pa., and south.
+                    _Atrachelus_ A. et S.
+
+                ii. Apical angle of the penultimate abdominal segment
+                    unarmed. _Fitchia_ (in part); _Castolus ferox_,
+                    Arizona.
+
+        ee. Sides of the mesosternum with a tubercle or fold in front at
+            the hind angles of the prosternum; first segment of the beak
+            longer than the part of the head cephalad of the eyes.
+
+          f. Fore femur thickened, densely granulated; hind femur
+              unarmed.
+
+[Illustration: 161. Taxonomic details of Diptera. (_a_) Ventral aspect
+of abdomen of Cynomyia; (_b_) antenna of Tabanus; (_c_) ventral aspect
+of abdomen of Chortophila; (_d_) ventral aspect of abdomen of Stomoxys;
+(_e_) claw of Aedes (Culex) sylvestris, male; (_f_) claw of Hippoboscid;
+(_g_) foot of dipterous insect showing empodium developed pulvilliform;
+(_h_) hind tarsal segment of Simulium vittatum, female; (_i_) foot of
+dipterous insect showing bristle-like empodium.]
+
+            g. Fore tibiæ each with three long spines on the ventral
+                side. _S. diadema_ (fig. 159e), a widely distributed
+                species; and several southwestern species. _Sinea_ A. et
+                S.
+
+            gg. Fore tibiæ unarmed. _A. multispinosa_, widely
+                distributed; _A. tabida_, Cal. _Acholla_ Stäl.
+
+          ff. Fore femur unarmed, rarely a little thickened, a little
+              granulated.
+
+            g. Pronotum produced caudad over the scutellum, with a high
+                mesal tuberculate ridge (fig. 19e). A. CRISTATUS. N. Y.
+                to Cal. and south. ARILUS Hahn.
+
+            gg. Caudal lobe of the pronotum six sided, neither elevated
+                nor produced caudad. _H. americanus_, Southwest; also
+                several W. I. and Mexican genera. HARPACTOR Lap.
+
+
+DIPTERA (Mosquitoes, Midges, Flies)
+
+a. Integument leathery, abdominal segments indistinct; wings often
+    wanting; parasitic forms. PUPIPARA
+
+  b. Head folding back on the dorsum of the thorax; wingless flies
+      parasitic on bats. Genus _Nycteribia_. NYCTERIBIIDÆ
+
+  bb. Head not folding back upon the dorsum of the thorax; flies either
+      winged or wingless; parasitic on birds and on bats and other
+      mammals.
+
+    c. Antennæ reduced, wings when present, with distinct parallel veins
+        and outer crossveins; claws simple; palpi leaf-like, projecting
+        in front of the head. Flies chiefly found on bats. Several
+        genera occur in North America. STREBLIDÆ
+
+[Illustration: 162. Hippobosca equina, ×4. After Osborn.]
+
+    cc. Antennæ more elongate, segments more or less distinctly
+        separated; head sunk into an emargination of the thorax; wings
+        when present with the veins crowded toward the anterior margin;
+        palpi not leaf-like. HIPPOBOSCIDÆ
+
+      d. Wings absent or reduced and not adapted for flight.
+
+        e. Wings and halteres (balancers) absent. _M. ovinus_, the sheep
+            tick. _Melophagus_ Latr.
+
+        ee. Wing reduced (or cast off), halteres present.
+
+          f. Claw bidentate; ocelli present. On deer after the wings are
+              cast off. _L. depressa_. _Lipoptena_ Nitsch
+
+          ff. Claw tridentate (fig. 161 f). On _Macropis_. _B.
+              femorata._ _Brachypteromyia_ Will.
+
+      dd. Wings present and adapted for flight.
+
+        e. Claws bidentate.
+
+          f. Ocelli present; head flat; wings frequently cast off. On
+              birds before casting of the wing. _Lipoptena_ Nitsch.
+
+          ff. Ocelli absent; head round; wings present. The horse tick
+              H. EQUINA may attack man (fig. 162). HIPPOBOSCA L.
+
+        ee. Claws tridentate (fig. 161 f.).
+
+          f. Anal cell closed at apical margin by the anal crossvein.
+
+            g. Ocelli absent. _Stilbometopa_ Coq.
+
+            gg. Ocelli present.
+
+              h. R_{4+5} does not form an angle at the crossvein. On
+                  birds. There is a record of one species of this genus
+                  attacking man. ORNITHOMYIA Latr.
+
+              hh. R_{4+5} makes an angle at the crossvein. _O.
+                  confluens_. _Ornithoica_ Rdi.
+
+          ff. Anal cell not closed by an anal crossvein. _Lynchia_,
+              _Pseudolfersia_, and _Olfersia_ are chiefly bird
+              parasites. The first mentioned genus is said to be the
+              intermediate host of _Hæmoproteus columbæ_.
+
+aa. Abdominal segments chitinous; not parasitic in the adult stage.
+
+  b. Antennæ with six or more segments and empodium not developed
+      pulvilliform; palpi often with four segments.
+
+    c. Ocelli present. BLEPHAROCERIDÆ, RHYPHIDÆ, BIBIONIDÆ,
+        MYCETOPHILIDÆ, besides some isolated genera of other families.
+
+    cc. Ocelli absent.
+
+      d. Dorsum of the thorax with a V-shaped suture; wings usually with
+          numerous veins; legs often very long and slender. Crane flies.
+          TIPULIDÆ
+
+      dd. Dorsum of the thorax without a V-shaped suture.
+
+        e. Not more than four longitudinal veins ending in the wing
+            margin; wing usually hairy: antennæ slender; coxæ not long;
+            tibiæ: without spurs, legs long and slender. Small, delicate
+            flies often called Gall gnats. CECIDOMYIIDÆ.
+
+        ee. More than four longitudinal veins ending in the wing margin.
+
+          f. The costal vein is not produced beyond the tip of the wing;
+              radius with not more than three branches.
+
+            g. Antennæ short, composed of ten or eleven closely united
+                segments; legs stout; body stout; abdomen oval; anterior
+                veins stout, posterior ones weak (fig. 163 b); eyes of
+                the male contiguous over the antennæ. Black flies,
+                buffalo flies, turkey gnats. Many North American
+                species, several of them notorious for their blood
+                sucking propensities. SIMULIIDÆ
+
+              h. Second joint of the hind tarsus with basal scale-like
+                  process and dorsal excision (fig. 161 h); radial
+                  sector not forked; no small cell at the base of the
+                  wing. _S. forbesi_, _jenningsi_, _johannseni_,
+                  _meridionale_, _piscicidium_, VENUSTUM, VITTATUM, etc.
+                  Widely distributed species (= EUSIMULIUM) SIMULIUM
+                  Latr.
+
+              hh. No basal scale-like process on the second joint of the
+                  hind tarsus; radial sector usually forked (fig. 163
+                  b).
+
+                i. Face broad, small basal cell of the wing present. _P.
+                    fulvum_, HIRTIPES, _mutatum_, PECUARUM, _pleurale_.
+                    PROSIMULIUM Roub.
+
+                ii. Face linear; small basal cell of the wing absent.
+                    One species, _P. furcatum_, from California.
+                    _Parasimulium_ Malloch
+
+            gg. Flies of a different structure.
+
+              h. Antennæ composed of apparently two segments and a
+                  terminal arista formed of a number of closely united
+                  segments. Rare flies with aquatic larvæ.
+                  ORPHNEPHILIDÆ
+
+              hh. Antennæ of six to fifteen segments, those of the male
+                  usually plumose; legs frequently slender and wings
+                  narrow CHIRONOMIDÆ
+
+                i. Media forked (except in the European genus
+                    _Brachypogon_); thorax without longitudinal fissure
+                    and not produced over the head (except in four
+                    exotic genera); antennæ usually fourteen-jointed in
+                    both sexes; fore tibia with a simple comb of setulæ,
+                    hind tibia with two unequal combs, middle tibia
+                    without comb. CERATOPOGONINÆ
+
+                  j. Thorax produced cap-like over the head, wing narrow
+                      and very long. _Jenkinsia_, _Macroptilum_ and
+                      _Calyptopogon_, eastern hemisphere;
+                      _Paryphoconus_, Brazil.
+
+                  jj. Thorax not produced over the head.
+
+                    k. Eyes pubescent, empodium well developed, or if
+                        short then R_{2+3} distinct and crossvein-like
+                        or the branches of R coalescent; r-m crossvein
+                        present; fore femora not thickened; wing either
+                        with appressed hairs or with microscopic erect
+                        setulæ _Dasyhelea_ Kieff.
+
+                    kk. Eyes bare, or otherwise differing from the
+                        foregoing.
+
+                      l. Empodium well developed, nearly as long as the
+                          claws and with long hairs at the base; femora
+                          and fifth tarsal segments unarmed, i.e.
+                          without spines or stout setæ; fourth tarsal
+                          segment cylindrical.
+
+                        m. Wing with erect and microscopic setulæ.
+                            Widely distributed. (= Atrichopogon)
+                            _Ceratopogon_ Meig.
+
+                        mm. Wing with long and depressed hairs. Widely
+                            distributed. _Forcipomyia_
+
+                          n. Hind metatarsus shorter or not longer than
+                              the following (i.e. the second tarsal)
+                              segment. Subgenus _Prohelea_ Kieff
+
+                          nn. Hind metatarsus longer than the following
+                              segment. Subgenus _Forcipomyia_ Meig.
+
+                      ll. Empodium short, scarcely reaching the middle
+                          of the claws, or vestigial.
+
+                        m. R-m crossvein wanting.
+
+                          n. Palpi four segmented; inferior fork of the
+                              media obliterated at the base. Australia.
+                              _Leptoconops_ Skuse
+
+                          nn. Palpi three-segmented.
+
+                            o. Legs spinulose, tarsal claws of the
+                                female with a basal tooth or strong
+                                bristle, those of the male unequal, the
+                                anterior with a long sinuous tooth, the
+                                posterior with a short arcuate tooth.
+                                Italy. MYCTEROTYPUS Noé
+
+                            oo. Legs unarmed; no crossvein between the
+                                branches of the radius (fig. 163e). New
+                                Mexico. TERSESTHES Townsend
+
+                        mm. R-m crossvein present.
+
+                          n. Fore femora very much swollen, armed with
+                              spines below, fore tibia arcuate and
+                              applied closely to the inferior margin of
+                              the femur.
+
+                            o. R_{2+3} present, therefore cell R_1 and
+                                R_2 both present; wing usually fasciate.
+                                United States _Heteromyia_ Say.
+
+                            oo. R_{2+3} not distinct from R_{4+5}, hence
+                                cell R_3 obliterated. South America
+                                _Pachyleptus_ Arrib. (Walker)
+
+                          nn. Fore femur not distinctly swollen.
+
+                            o. R_{2+3} present therefore cells R_1 and
+                                R_3 both present, or if not, then the
+                                branches of the radius more or less
+                                coalescent, obliterating the cells.
+
+                              p. At least the tip of the wing with erect
+                                  setulæ; tip of R_{4+5} scarcely
+                                  attaining the middle of the wing,
+                                  empodium rather indistinct, not
+                                  reaching the middle of the claws, the
+                                  claws not toothed, equal, with long
+                                  basal bristle; legs without stout
+                                  setæ. Widely distributed. CULICOIDES
+                                  Latr.
+
+                                HÆMATOMYIDIUM and OECACTA are probable
+                                    synonyms of this.
+
+                              pp. Wings bare, if rarely with hair, then
+                                  the radius reaches beyond two-thirds
+                                  the length of the wing, or the femur
+                                  or fifth tarsal segment with stout
+                                  black spines.
+
+                                q. Media unbranched. Europe.
+                                    _Brachypogon_ Kieff
+
+                                qq. Media branched.
+
+                                  r. Hind femur much swollen and spined.
+                                      America and Europe. _Serromyia_
+                                      Meg.
+
+                                  rr. Hind femur not distinctly swollen.
+
+                                    s. Cell R_1 not longer than high;
+                                        fork of the media distad of the
+                                        crossvein; wing with microscopic
+                                        setulæ _Stilobezzia_ Kieff
+
+                                    ss. Cell R_1 elongate.
+
+                                      t. Femora unarmed. Widely
+                                          distributed. (= Sphaeromias
+                                          Kieff. 1913 not Curtis?).
+                                          JOHANNSENIELLA Will.
+
+                                      tt. Femora, at least in part, with
+                                          strong black spines. Widely
+                                          distributed. _Palpomyia_
+                                          Megerle
+
+                            oo. R_{2+3} coalescent with R_{4+5} hence
+                                cell R_3 is obliterated.
+
+                              p. In the female the lower branch of the
+                                  media with an elbow near its base
+                                  projecting proximad, the petiole of
+                                  the media coalescent with the basal
+                                  section of the radius, wing long and
+                                  narrow, radial sector ending near the
+                                  tip of the wing; venation of the male
+                                  as in _Bezzia_; front concave. United
+                                  States. _Stenoxenus_ Coq.
+
+                              pp. Venation otherwise, front not concave.
+
+                                q. Subcosta and R_1 more or less
+                                    coalescent with the costa; wing
+                                    pointed at the apex, much longer
+                                    than the body; antennæ fourteen
+                                    segmented, not plumose. India.
+                                    _Haasiella_ Kieff.
+
+                                qq. Subcosta and radius distinct from
+                                    the costa.
+
+                                  r. Abdomen petiolate. _Dibezzia_
+                                      Kieff.
+
+                                  rr. Abdomen not petiolate.
+
+                                    s. Head semi-globose; hind tarsi
+                                        unusually elongate in the
+                                        female; antennæ of the male not
+                                        plumose. Europe. _Macropeza_
+                                        Meigen.
+
+                                    ss. Head not globose, more or less
+                                        flattened in front; antennæ of
+                                        the male plumose. Widely
+                                        distributed. _Bezzia_ Kieff.
+
+                                      t. Fore femora, at least, armed
+                                          with stout spines below.
+                                          Subgenus _Bezzia_ Kieff.
+
+                                      tt. Femora unarmed. Subgenus
+                                          _Probezzia_ Kieff.
+
+                ii. Media of the wing simple, and otherwise not as in
+                    "i". To this group belong numerous Chironomid
+                    genera, none of which are known to be noxious to
+                    man.
+
+          ff. The costal vein apparently is continued around the hind
+              margin of the wing; radius with at least four branches.
+
+            g. Wing ovate pointed, with numerous veins; crossveins, if
+                evident, before the basal third of the wing; veins very
+                hairy; very small moth-like flies. PSYCHODIDÆ
+
+              h. With elongate biting proboscis; the petiole of the
+                  anterior forked cell of the wing (R_2) arises at or
+                  beyond the middle of the wing (fig. 163d). PHLEBOTOMUS
+                  Rdi.
+
+[Illustration: 163. Wings of Diptera. (_a_) Anopheles; (_b_)
+Prosimulium; (_c_) Johannseniella; (_d_) Phlebotomus (After Doerr and
+Russ); (_e_) Tersesthes (after Townsend); (_f_) Tabanus; (_g_)
+Symphoromyia; (_h_) Aphiochæta; (_i_) Eristalis; (_j_) Gastrophilus;
+(_k_) Fannia; (_l_) Musca.]
+
+              hh. With shorter proboscis; the petiole of the anterior
+                  forked cell arises near the base of the wing.
+                  _Psychoda_, _Pericoma_, etc.
+
+            gg. The r-m crossvein placed at or beyond the center of the
+                wing; wings not folded roof-like over the abdomen.
+
+              h. Proboscis short, not adapted for piercing; wings bare
+                  (DIXIDÆ); or wings scaled (CULICIDÆ, Subf.
+                  CORETHRINÆ).
+
+              hh. Proboscis elongate, adapted for piercing; wings
+                  scaled, fringed on the hind margin; antennæ of the
+                  male bushy plumose. Mosquitoes. CULICIDÆ (exclusive of
+                  CORETHRINÆ)
+
+                i. Metanotum without setæ.
+
+                  j. Proboscis strongly decurved; body with broad,
+                      appressed, metalescent scales; cell R_2 less than
+                      half as long as its petiole; claws of female
+                      simple, some of the claws of the male toothed.
+                      Several large southern species believed to feed
+                      only on nectar of flowers. _Megarhinus_ R. D.
+
+                  jj. Proboscis straight or nearly so, or otherwise
+                      different.
+
+                    k. Scutellum evenly rounded, not lobed; claws simple
+                        in both sexes. ANOPHELES Meig.
+
+                      l. Abdomen with clusters of broad outstanding
+                          scales along the sides; outstanding scales on
+                          the veins of the wing rather narrow,
+                          lanceolate; upper side of the thorax and
+                          scutellum bearing many appressed lanceolate
+                          scales. Florida and southward (CELLIA).
+
+                        m. Hind feet from the middle of the second
+                            segment largely or wholly snow white.
+
+                          n. With a black band at the base of the last
+                              segment of each hind foot. A.
+                              ALBIMANUS*[H] and TARSIMACULATA*
+
+                          nn. Without such a band A. ARGYRITARSIS*
+
+                        mm. Hind feet black, mottled with whitish and
+                            with bands of the same color at the sutures
+                            of the segments. W. I. A. MACULIPES
+
+                      ll. Abdomen without such a cluster of scales;
+                          outstanding scales of the wing veins rather
+                          narrow, lanceolate; tarsi wholly black.
+
+                        m. Deep black, thorax obscurely lined with
+                            violaceous, especially posteriorly; head,
+                            abdomen and legs black; no markings on the
+                            pleura; abdomen without trace of lighter
+                            bindings; wing scales outstanding, uniform,
+                            not forming spots, though little thicker at
+                            the usual points indicating the spottings.
+                            Florida. A. ATROPUS
+
+                        mm. Otherwise marked when the wings are
+                            unspotted.
+
+                          n. Wings unspotted.
+
+                            o. Petiole of the first forked cell (R_2)
+                                more than a third the length of the
+                                cell. Mississippi valley. A. WALKERI
+
+                            oo. Petiole of the first forked cell a third
+                                the length of the cell. Md. A. BARBERI
+
+                          nn. Wings spotted.
+
+                            o. Front margin of the wings with a patch of
+                                whitish and yellow scales at a point
+                                about two-thirds or three-fourths of the
+                                way from base to apex of wing.
+
+                              p. Veins of the wing with many broad
+                                  obovate outstanding scales; thorax
+                                  with a black dot near the middle of
+                                  each side. W. I. A. GRABHAMI*
+
+                              pp. The outstanding scales of the wings
+                                  rather narrow, lanceolate.
+
+                                q. Scales of the last vein of the wings
+                                    white, those at each end black;
+                                    R_{4+5} black scaled, the extreme
+                                    apex white scaled. Widely
+                                    distributed north and south (fig.
+                                    131). A. PUNCTIPENNIS
+
+                                  A dark variety from Pennsylvania has
+                                      been named A. PERPLEXENS.
+
+                                qq. Scales of the last vein of the wing
+                                    white, those at its apex black;
+                                    R_{4+5} white scaled and with two
+                                    patches of black scales. South and
+                                    the tropics. A. FRANCISCANUS and
+                                    PSEUDOPUNCTIPENNIS*
+
+                            oo. Front margin of the wings wholly black
+                                scaled.
+
+                              p. Last (anal) vein of the wings white
+                                  scaled with three patches of black
+                                  scales (fig. 132). New Jersey to
+                                  Texas. A. CRUCIANS*
+
+                              pp. Last vein of the wings wholly black
+                                  scaled.
+
+                                q. Widely distributed north and south
+                                    (fig. 130), (= MACULIPENNIS). A.
+                                    QUADRIMACULATUS*
+
+                                qq. Distributed from Rocky Mountains
+                                    westward. A. OCCIDENTALIS
+
+                    kk. Scutellum distinctly trilobed.
+
+                      l. Cell R_2 less than half as long as its petiole;
+                          thorax with metallic blue scales; median lobe
+                          of the scutellum not tuberculate; few small
+                          species which are not common. URANOTÆNIA
+                          Arrib.
+
+                      ll. Cell R_2 nearly or quite as long as its
+                          petiole, or otherwise distinct.
+
+                        m. Femora with erect outstanding scales; occiput
+                            broad and exposed. Large species. P.
+                            CILIATA. P. HOWARDI PSOROPHORA R. D.
+
+                        mm. Femora without erect scales.
+
+                          n. Clypeus bearing several scales or hairs,
+                              scutellum with broad scales only; back of
+                              head with broad scales; scales along the
+                              sides of the mesonotum narrow; some or the
+                              claws toothed; thorax marked with a pair
+                              of silvery scaled curved stripes; legs
+                              black with white bands at the bases of
+                              some of the segments (fig. 134). Yellow
+                              Fever mosquito. AEDES (= STEGOMYIA)
+                              CALOPUS.
+
+                          nn. With another combination of characters.
+                              Numerous species of mosquitoes belonging
+                              to several closely related genera, widely
+                              distributed over the country. (_Culex_,
+                              _Aedes_, _Ochlerotatus_, etc.). CULEX in
+                              the wide sense.
+
+                ii. Metanotum with setæ. _Wyeomyia_ (found in the United
+                    States); and related tropic genera.
+
+  bb. Antennæ composed of three segments with a differentiated style or
+      bristle; third segment sometimes complex or annulate, in which
+      case the empodium is usually developed like the pulvilli, i.e.,
+      pad-like (fig. 161 g).
+
+    c. Empodium developed pad-like (pulvilliform) i.e., three nearly
+        equal membranous appendages on the underside of the claw (fig.
+        161g).
+
+      d. Squamæ, head, and eyes large; occiput flattened or concave;
+          third segment of the antennæ with four to eight annuli or
+          segments, proboscis adapted for piercing; body with fine
+          hairs, never with bristles; middle tibia with two spurs; wing
+          venation as figured (fig. 163f); marginal vein encompasses the
+          entire wing. Horse flies, greenheads, deer flies, gad flies
+          TABANIDÆ[I]
+
+        e. Hind tibia with spurs at tip; ocelli usually present
+            (PANGONINÆ)
+
+          f. Third joint of the antennæ with seven or eight segments;
+              proboscis usually prolonged.
+
+            g. Each section the third antennal segment branched. Central
+                American species, _P. festæ_. _Pityocera_ G. T.
+
+            gg. Sections of the third antennal segment not branched.
+
+              h. Upper corner of the eyes in the female terminating in
+                  an acute angle; wings of both sexes dark anteriorly.
+                  _G. chrysocoma_, a species from the eastern states.
+                  _Goniops_ Ald.
+
+              hh. Upper corner of the eye in the female not so
+                  terminating; wings nearly uniform in color, or
+                  hyaline.
+
+                i. Proboscis scarcely extending beyond the palpi; front
+                    of the female wide; much wider below than above. S.
+                    W. States. _Apatolestes_ Will.
+
+                ii. Proboscis extending beyond the palpi.
+
+                  j. Wing with cell M_3 closed. Tropic America. (=
+                      _Diclisa_) _Scione_ Wlk.
+
+                  jj. Cell M_3 open; ocelli present or absent. Two or
+                      three eastern species; many south and west
+                      PANGONIA Rdi.
+
+          ff. Third segment of the antenna with five divisions; ocelli
+              present.
+
+            g. First and second segments of the antenna short, the
+                second only half as long as the first, three western
+                species. SILVIUS Rdi.
+
+            gg. First and second segments of the antenna long, the
+                second distinctly over half as long as the first. Deer
+                flies. Many species, widely distributed. CHRYSOPS Meig.
+
+        ee. Hind tibia without spurs; ocelli absent.
+
+          f. Third segment of antenna with four divisions, no tooth or
+              angulation; wings marked with rings and circles of darker
+              coloring; front of the female very wide. Widely
+              distributed. _H. americana_, _H. punctulata_. HÆMATOPOTA
+              Meig.
+
+          ff. Third segment of the antenna with five divisions (fig.
+              161b).
+
+            g. Third segment of the antenna not furnished with a tooth
+                or distinct angular projection.
+
+              h. Body covered with metallic scales; front of female of
+                  normal width; front and middle tibiæ greatly dilated.
+                  _L. lepidota_. _Lepidoselaga_ Macq.
+
+              hh. Body without metallic scales; antennæ not very long,
+                  the third segment not cylindrical, not situated on a
+                  projecting tubercle; front of the female narrow.
+                  South. _D. ferrugatus._ (= _Diabasis_) _Diachlorus_ O.
+                  S.
+
+            gg. Third segment of the antenna furnished with a tooth or a
+                distinct angular projection.
+
+              h. Hind tibiæ ciliate with long hairs. S. W. and tropics.
+                  _Snowiella_ and _Stibasoma_.
+
+              hh. Hind tibiæ not ciliate.
+
+                i. Species of slender build, usually with a banded
+                    thorax and abdomen; third segment of the antenna
+                    slender, the basal prominence long; wings mostly
+                    with brownish markings. Tropic America.
+                    _Dichelacera_ Macq.
+
+                ii. Species of a stouter build; third segment of the
+                    antenna stout, its basal process short (fig. 161b).
+                    Many species, widely distributed TABANUS L.
+
+      dd. With another group of characters.
+
+        e. Squamæ small, antennæ variable, thinly pilose or nearly bare
+            species, without distinct bristles; wing veins not crowded
+            anteriorly, R_4 and R_5 both present, basal cells large;
+            middle tibiæ at least with spurs. LEPTIDÆ
+
+          f. Flagellum of the antenna more or less elongated, composed
+              of numerous more or less distinct divisions. XYLOPHAGINÆ
+              and ARTHROCERATINÆ.
+
+          ff. Antennæ short, third segment simple, with arista or style;
+              face small, proboscis short LEPTINÆ
+
+            g. Front tibiæ each with one or two spurs, or if absent,
+                then no discal cell. _Triptotricha_, _Pheneus_,
+                _Dialysis_, _Hilarimorpha_.
+
+            gg. Front tibiæ without terminal spurs, discal cell present.
+
+              h. Hind tibiæ each with a single spur.
+
+                i. Anal cell open (fig. 163g); third antennal segment
+                    kidney-shaped with dorsal or subdorsal arista; first
+                    antennal segment elongate and thickened. About a
+                    dozen species have been described from the United
+                    States, of which at least one (S. PACHYCERAS) is
+                    known to be a vicious blood sucker. SYMPHOROMYIA
+                    Frauenf.
+
+                ii. Anal cell closed; third antennal segment not
+                    kidney-shaped. _Chrysopila_, _Ptiolina_, _Spania_.
+
+              hh. Hind tibiæ each with two spurs.
+
+                i. Third segment kidney-shaped, the arista subdorsal;
+                    anal cell closed. _Atherix_ Meig.
+
+                ii. Third segment of the antenna short and with terminal
+                    arista; anal cell open _Leptis_ Fabr. Two European
+                    species of this genus have been accused of blood
+                    sucking habits, but the record seems to have been
+                    based upon error in observation.
+
+        ee. With another combination of characters. STRATIOMYIIDÆ,
+            CYRTIDÆ, etc.
+
+    cc. Empodium bristlelike or absent.
+
+      d. Antennæ apparently two segmented, with three-segmented arista,
+          wings (rarely wanting) with several stout veins anteriorly,
+          the weaker ones running obliquely across the wing (fig. 163h);
+          small, quick running, bristly, humpbacked flies. Several
+          genera; APHIOCHÆTA, PHORA, TRINEURA, etc. PHORIDÆ
+
+      dd. Flies with other characters.
+
+        e. No frontal lunule above the base of the antennæ; both R_4 and
+            R_5 often present; third segment of the antenna often with a
+            terminal bristle. ASILIDÆ, MYDAIDÆ, APIOCERIDÆ, THEREVIDÆ,
+            SCENOPINIDÆ, BOMBYLIIDÆ, EMPIDIDÆ, DOLICHOPODIDÆ,
+            LONCHOPTERIDÆ.
+
+        ee. A frontal lunule above the base of the antennæ; third
+            segment of the antenna always simple, i.e., not ringed,
+            usually with a dorsal arista; R_4 and R_5 coalesced into a
+            simple vein.
+
+          f. A spurious vein or fold between the radius and the media,
+              rarely absent; the cell R_{4+5} closed at the apex by vein
+              M_1; few or no bristles on the body, none on the head;
+              flies frequently with yellow markings. ERISTALIS (fig.
+              163i), HELOPHILUS, and many other genera. SYRPHIDÆ
+
+          ff. No spurious vein present.
+
+            g. Body without bristles; proboscis elongate and slender,
+                often folding; front of both male and female broad.
+                CONOPIDÆ
+
+            gg. Bristles almost always present on head, thorax, abdomen
+                and legs.
+
+              h. Arista terminal; hind metatarsus enlarged, sometimes
+                  ornamented, hind tarsus more or less flattened beneath
+                  PLATYPEZIDÆ
+
+              hh. Flies having a different combination of characters.
+
+                i. Head large, eyes occupying nearly the entire head;
+                    cell R_{4+5} narrowed in the margin; small flies.
+                    PIPUNCULIDÆ
+
+                ii. Head and eyes not unusually large.
+
+                  j. Squamæ (tegulæ, or calyptræ, or alulæ) not large,
+                      often quite small, the lower one lacking, or at
+                      most barely projecting from below the upper one
+                      (antisquama); front of both male and female broad,
+                      the eyes therefore widely separated; posthumeral
+                      and intraalar macrochæta not simultaneously
+                      present; thorax usually without a complete
+                      transverse suture; postalar callus usually absent;
+                      the connectiva adjoining the ventral sclerites
+                      always visible; hypopleural macrochætæ absent;
+                      last section of R_{4+5} and M_{1+2} with but few
+                      exceptions nearly parallel; subcostal vein often
+                      wanting or vestigial or closely approximated to
+                      R_1; the latter often short, basal cells small,
+                      the posterior ones often indistinct or wanting;
+                      vibrissæ present or absent. ACALYPTRATE MUSCOIDEA
+
+                    k. Subcosta present, distinctly separated from R_1
+                        at the tip; R_1 usually ends distad of the
+                        middle of the wing; the small basal cells of the
+                        wing distinct.
+
+                      l. A bristle (vibrissa) on each side of the face
+                          near the margin of the mouth. CORDYLURIDÆ,
+                          SEPSIDÆ, PHYCODROMIDÆ, HETERONEURIDÆ,
+                          HELOMYZIDÆ.
+
+                      ll. No vibrissæ present.
+
+                        m. Head nearly spherical, cheeks broad and
+                            retreating; proboscis short; the cell R_5
+                            closed or narrowed in the margin; legs very
+                            long; tarsi shorter than the tibiæ. CALOBATA
+                            and other genera. MICROPEZIDÆ
+
+                        mm. Flies with another combination of
+                            characters. RHOPALOMERIDÆ, TRYPETIDÆ,
+                            ORTALIDÆ, SCIOMYZIDÆ.
+
+                    kk. Subcosta absent or vestigial, or if present,
+                        then apparently ending in the costa at the point
+                        where R_1 joins it; R_1 usually ends in the
+                        costa at or before the middle of the wing.
+
+                      l. Arista long plumose, or pectinate above; oral
+                          vibrissæ present; anal cell complete; costa
+                          broken at the apex of R_1. DROSOPHILA,
+                          PHORTICA, and other genera. DROSOPHILIDÆ
+
+                      ll. With another combination of characters.
+
+                        m. The cell M and first M_2 not separated by a
+                            crossvein; anal cell absent; front bare or
+                            only bristly above; usually light colored
+                            flies. HIPPELATES, OSCINUS, and other
+                            genera. (See also m m m.) OSCINIDÆ
+
+                        mm. Cell M and cell first M_2 often separated by
+                            a crossvein; anal cell present, complete,
+                            though frequently small; scutellum without
+                            spines or protuberances; oral vibrissæ
+                            present; arista bare or short plumose; front
+                            bristly at vertex only; small dark flies.
+                            PIOPHILA (fig. 99), SEPSIS and other genera.
+                            SEPSIDÆ
+
+                        mmm. The GEOMYZIDÆ, AGROMYZIDÆ, PSILIDÆ,
+                            TRYPETIDÆ, RHOPALOMERIDÆ, BORBORIDÆ and
+                            DIOPSIDÆ differ in various particulars from
+                            either the OSCINIDÆ and the SEPSIDÆ noted
+                            above.
+
+                  jj. Squamæ well developed, usually large, the lower
+                      one frequently projecting from below the upper
+                      one; both posthumeral and intraalar macrochætæ
+                      present; thorax with a complete transverse suture;
+                      postalar callus present and separated by a
+                      distinct suture from the dorsum of the thorax;
+                      front of the female broad, of the male frequently
+                      narrow, the eyes then nearly or quite contiguous;
+                      the connectiva adjoining the ventral sclerites
+                      either visible or not; hypopleural macrochætæ
+                      present or absent; subcosta always distinct in its
+                      whole course, R_1 never short. CALYPTRATE
+                      MUSCOIDEA[J]
+
+                    k. Oral opening small, mouth parts usually much
+                        reduced or vestigial. This family is undoubtedly
+                        of polyphyletic origin but for convenience it is
+                        here considered as a single family. OESTRIDÆ.
+
+                      l. The costal vein ends at the tip of R_{4+5},
+                          M_{1+2} straight, not reaching the wing
+                          margin, hence cell R_5 wide open (fig. 163j);
+                          squamæ small; arista bare; ovipositor of the
+                          female elongate. Larvæ in the alimentary canal
+                          of horses, etc. GASTROPHILUS
+
+                        m. Posterior crossvein (m-cu) wanting; wings
+                            smoky or with clouds. Europe. G. PECORUM
+
+                        mm. Posterior crossvein (m-cu) present, at least
+                            in part.
+
+                          n. Wing hyaline with smoky median cross band,
+                              and two or three spots; posterior
+                              trochanters with hook in the male and a
+                              prominence in the female. World wide
+                              distribution. G. EQUI.
+
+                          nn. Wings without spots.
+
+                            o. Posterior crossvein (m-cu) distad of the
+                                anterior crossvein (r-m); legs,
+                                particularly the femora, blackish brown.
+                                Europe and North America. G.
+                                HÆMORRHOIDALIS
+
+                            oo. Posterior crossvein opposite or proximad
+                                of the anterior crossvein. Europe and
+                                North America. G. NASALIS
+
+                      ll. The costal vein ends at the tip of M_{1+2},
+                          M_{1+2} with a bend, the cell R_5 hence much
+                          narrowed in the margin, or closed.
+
+                        m. Proboscis geniculate, inserted in a deep
+                            slit; female without extricate ovipositor;
+                            arista either bare or plumose; squamæ large;
+                            facial grooves approximated below.
+
+                          n. Arista bare, short. Larvæ in rodents.
+                              Tropic America. _B. princeps_. _Bogeria_
+                              Austen
+
+                          nn. Arista pectinate above.
+
+                            o. Tarsi broadened and flattened, hairy,
+                                anal lobe of the wing large. Larvæ in
+                                rodents. A number of American species.
+                                _Cuterebra_.
+
+                            oo. Tarsi slender, not hairy; anal lobe of
+                                the wing moderate. Larvæ in man and
+                                other mammals. Tropic America. D.
+                                CYANIVENTRIS. DERMATOBIA Br.
+
+                        mm. Mouth parts very small, vestigial; arista
+                            bare.
+
+                          n. Facial grooves approximated below, leaving
+                              a narrow median depression or groove.
+
+                            o. Cell R_5 closed and petiolate, body
+                                nearly bare. Larvæ in the nasal cavities
+                                of the smaller Ungulates. The sheep bot
+                                fly. O. OVIS. Widely distributed OESTRUS
+                                L.
+
+                            oo. Cell R_5 narrowly open, body hairy.
+                                Larvæ parasitic on deer. Europe and
+                                America. _Cephenomyia_ Latr.
+
+                          nn. Facial grooves far apart, enclosing
+                              between them a broad shield-shaped
+                              surface; squamæ large; female with
+                              elongate ovipositor. Larvæ hypodermatic on
+                              Ungulates HYPODERMA Clark
+
+                            o. Palpi wanting; tibiæ thickened in the
+                                middle.
+
+                              p. Hair at apex of the abdomen yellow;
+                                  legs including femora yellowish brown.
+                                  H. DIANA
+
+                              pp. Hair at the apex of the abdomen
+                                  reddish yellow. Europe and America.
+
+                                q. Tibiæ and tarsi yellow; femora black.
+                                    H. LINEATA
+
+                                qq. Legs black with black hair; tips of
+                                    hind tibia and tarsi yellowish
+                                    brown. H. BOVIS
+
+                            oo. Palpi small, globular; tibiæ
+                                cylindrical, straight. On reindeer. _O.
+                                tarandi_ _Oedemagena_ Latr.
+
+                    kk. Oral opening of the usual size; mouth parts not
+                        vestigial.
+
+                      l. Hypopleurals wanting; if three sternopleurals
+                          are present the arrangement is 1:2;
+                          conjunctiva (fig. 161c) of the venter usually
+                          present; if the terminal section of M_{1+2} is
+                          bent it has neither fold nor appendage
+                          (ANTHOMYIIDÆ of Girschner).
+
+                        m. Sternopleurals wanting; M_{1+2} straight
+                            toward the apex, costa ends at or slightly
+                            beyond the tip of R_{4+5}; mouth parts
+                            vestigial. GASTROPHILINÆ. See OESTRIDÆ
+
+                        mm. Sternopleurals present, if rarely absent
+                            then differing in other characters.
+
+                          n. Caudal margin of the fifth ventral
+                              abdominal sclerite of the male deeply
+                              notched on the median line usually to
+                              beyond the middle; abdomen often
+                              cylindrical or linear; abdomen often with
+                              four to eight spots; eyes of the male
+                              usually widely separated; sternopleurals
+                              three, arranged in an equilateral
+                              triangle; subapical seta of the hind tibia
+                              placed very low; M_{1+2} straight; anal
+                              vein abbreviated; wings not rilled.
+                              _Cænosia_, _Caricea_, _Dexiopsis_,
+                              _Hoplogaster_, _Schoenomyia_, etc.
+                              (COENOSINÆ)[K]. ANTHOMYIIDÆ in part
+
+                          nn. Caudal margin of the fifth ventral
+                              abdominal sclerite of the male incurved,
+                              rarely deeply cleft, rarely entire, in a
+                              few genera deeply two or three notched;
+                              M_{1+2} straight or curved; abdomen
+                              usually short or elongate oval;
+                              sternopleurals, if three are present,
+                              arranged in the order 1:2 in a right
+                              triangle. (MUSCINÆ-ANTHOMYIINÆ of
+                              Girschner)
+
+                            o. M_{1+2} straight, hence cell R_5 not
+                                narrowed in the margin. ANTHOMYIIDÆ in
+                                part
+
+                              p. Underside of the scutellum more or less
+                                  sparsely covered with fine hairs; anal
+                                  vein nearly always reaches the hind
+                                  margin of the wing; extensor surface
+                                  of the hind tibiæ with a number of
+                                  stout setæ; squamæ often small and
+                                  equal. ANTHOMYIA, _Chortophila_,
+                                  _Eustalomyia_, _Hammomyia_,
+                                  _Hylemyia_, _Prosalpia_, _Pegomyia_,
+                                  etc. HYLEMYINÆ-PEGOMYINÆ
+
+                              pp. Underside of the scutellum bare; anal
+                                  vein does not reach the wing margin.
+
+                                q. First anal vein short, second anal
+                                    suddenly flexed upwards; hind tibiæ
+                                    each with one or two strong setæ on
+                                    the extensor surface. FANNIA (=
+                                    HOMALOMYIA), _Coelomyia_,
+                                    _Choristoma_, _Euryomma_, _Azelia_,
+                                    etc. FANNINÆ-AZELINÆ
+
+                                qq. Anal veins parallel or divergent.
+
+                                  r. Setæ on the exterior surface of the
+                                      hind tibiæ wanting (except in
+                                      _Limnaricia_ and _Coenosites_),
+                                      lower squama not broadened to the
+                                      margin of the scutellum.
+                                      _Leucomelina_, _Limnophora_,
+                                      _Limnospila_, _Lispa_, _Mydæa_,
+                                      _Spilogaster_, etc.
+                                      MYDÆINÆ-LIMNOPHORINÆ
+
+                                  rr. One (rarely more) seta on the
+                                      extensor surface of the hind
+                                      tibia; squamæ usually large and
+                                      unequal. HYDROTAEA, _Aricia_,
+                                      _Drymeia_, _Ophyra_, _Phaonia_ (=
+                                      _Hyetodesia_), _Pogonomyia_,
+                                      _Trichophthicus_, etc. ARICINÆ
+
+                            oo. M_{1+2} curved or bent, hence the cell
+                                R_5 more or less narrowed in the margin.
+                                (MUSCINÆ). MUSCIDÆ in part. See page 303
+                                for generic synopsis.
+
+                      ll. Hypopleurals present; when three
+                          sternopleurals are present the arrangement is
+                          2:1 or 1:1:1. (TACHINIDÆ of Girschner)
+
+                        m. Conjunctiva of the ventral sclerites of the
+                            abdomen present, frequently well developed,
+                            surrounding the sclerites.
+
+                          n. Mouth parts vestigial. OESTRIDÆ. See page
+                              297 for generic synopsis.
+
+                          nn. Mouth parts well developed.
+
+                            o. M_{1+2} straight, hence cell R_5 wide
+                                open in the margin; costa ending at the
+                                tip of R_5; three sternopleurals
+                                present; antennal arista plumose.
+                                _Syllegoptera_. Europe.
+                                (SYLLEGOPTERINÆ). DEXIIDÆ in part
+
+                            oo. M_{1+2} bent, hence cell R_5 narrowed in
+                                the margin; sternopleurals rarely
+                                wanting, usually 1:1 or 0:1; facial
+                                plate strongly produced below vibrissal
+                                angle like the bridge of the nose;
+                                antennal arista bare. Parasitic on
+                                Hemiptera and Coleoptera. _Allophora_,
+                                _Cistogaster_, _Clytia_, _Phasia_, etc.
+                                (PHASIINÆ) TACHINIDÆ in part.
+
+                        mm. Conjunctiva of the ventral sclerites
+                            invisible (fig. 161a).
+
+                          n. Second ventral sclerite of the abdomen
+                              lying with its edges either upon or in
+                              contact with the ventral edges of the
+                              corresponding dorsal sclerite.
+
+                            o. Outermost posthumeral almost always lower
+                                (more ventrad) in position than the
+                                presutural macrochæta; fifth ventral
+                                abdominal sclerite of the male cleft
+                                beyond the middle, often strongly
+                                developed; body color very frequently
+                                metallic green or blue, or yellow;
+                                arista plumose. (CALLIPHORINÆ) MUSCIDÆ
+                                in part.
+
+                              See page 303 for generic synopsis.
+
+                            oo. Outermost posthumeral macrochæta on
+                                level or higher (more dorsad) than the
+                                presutural macrochæta; arista bare,
+                                pubescent, or plumose only on the basal
+                                two-thirds; body coloring usually
+                                grayish (fig. 106). SARCOPHAGIDÆ
+
+                              p. Fifth ventral sclerite of the male
+                                  either wanting or with the caudal
+                                  margin straight; presutural intraalar
+                                  rarely present. (SARCOPHAGINÆ)
+
+                                q. Fifth ventral abdominal sclerite of
+                                    the male much reduced, the remaining
+                                    segments with straight posterior
+                                    margin, overlapping scale-like; in
+                                    the female only segment one and two
+                                    scale-like, the others wholly or in
+                                    part covered; sternopleurals usually
+                                    three or more. SARCOPHAGA and
+                                    related genera.
+
+                                qq. Fifth ventral sclerite of the male
+                                    plainly visible; sternopleurals
+                                    usually two. SARCOPHILA,
+                                    WOHLFAHRTIA, _Brachycoma_,
+                                    _Hilarella_, _Miltogramma_,
+                                    _Metopia_, _Macronychia_, _Nyctia_,
+                                    _Paramacronychia_, _Pachyphthalmus_,
+                                    etc.
+
+                              pp. Fifth ventral abdominal sclerite of
+                                  the male cleft to beyond the middle;
+                                  ventral sclerites usually visible,
+                                  shield-like. _Rhinophora_, _Phyto_,
+                                  _Melanophora_ RHINOPHORINÆ
+
+[Illustration: 164. Glossina palpalis. (×4.) After Austen.]
+
+                          nn. Second ventral abdominal sclerite as well
+                              as the others more or less covered,
+                              sometimes wholly, by the edges of the
+                              dorsal sclerite.
+
+                            o. The presutural intraalar wanting; ventral
+                                sclerites two to five nearly or quite
+                                covered by the edges of the
+                                corresponding dorsal sclerites; base of
+                                the antennæ usually at or below the
+                                middle of the eye; arista usually
+                                plumose; legs usually elongate;
+                                abdominal segments with marginal and
+                                often discal macrochætæ. DEXIIDÆ
+
+                            oo. Presutural intraalar present, if absent,
+                                then the ventral sclerites broadly
+                                exposed or the fifth ventral sclerite
+                                vestigial; base of the antennæ usually
+                                above the middle of the eye; arista
+                                bare; at least two posthumerals and
+                                three posterior intraalars present.
+                                Parasitic on caterpillars, etc.
+                                TACHINIDÆ
+
+
+SYNOPSIS OF THE PRINCIPAL GENERA OF THE MUSCIDÆ OF THE WORLD
+
+a. Proboscis long, directed forward, adapted for piercing, or oral
+    margin much produced, snout-like.
+
+  b. Oral margin produced snout-like; vibrissa placed high above the
+      oral margin; antennal arista either pectinate or more or less
+      plumose.
+
+    c. Antennal arista short or long-plumose; neither sex with distinct
+        orbital bristles.
+
+      d. No facial carina between the antennæ. RHYNCHOMYIINÆ
+
+        e. Arista short-plumose. _R. speciosa._ Europe. _Rhynchomyia_ R.
+            D.
+
+        ee. Arista long-plumose. _I. phasina_. Europe and Egypt.
+            _Idiopsis_. B. B.
+
+      dd. With flattened carina, the bases of the antennæ separated; no
+          abdominal macrochætæ. COSMININÆ _C. fuscipennis_. South
+          Africa. _Cosmina_
+
+    cc. Antennal arista pectinate; bases of the antennæ separated by a
+        flattened carina. RHINIINÆ R. D.
+
+      d. Cell R_5 open, or closed at the margin.
+
+        e. Third segment of the antenna twice as long as the second;
+            claws of both sexes short; cell R_5 open. _I. lunata._
+            Eastern Hemisphere. _Idia_ Meigen
+
+        ee. Third segment of the antenna three times as long as the
+            second; cell R_5 open or closed; claws of the male long and
+            slender, of the female shorter than the last tarsal joint.
+            _I. mandarina_, China. _Idiella_ B. B.
+
+      dd. Cell R_5 petiolate. _Rhinia_; and _Beccarimyia_ Rdi.
+
+  bb. Proboscis long, directed forward, adapted for piercing. STOMOXINÆ
+
+    c. Arista flat, pectinate above with plumose rays; sternopleurals
+        1:2; bases of the veins R_1 and R_{4+5} without setæ; base of
+        the media bowed down; apical cell opens before the apex of the
+        wing. African species. GLOSSINA Wied.
+
+      d. Species measuring over twelve mm. in length. _G. longipennis_
+          and FUSCA.
+
+      dd. Species less than twelve mm. in length.
+
+        e. All segments of the hind tarsi black.
+
+          f. The fourth and fifth segments of the fore tarsi black;
+              antennæ black (fig. 164). G. PALPALIS R. D.
+
+          ff. Otherwise marked. _G. bocagei_, _tachinoides_,
+              _pallicera._
+
+        ee. First three segments of the hind tarsi are yellow, the
+            fourth and fifth segments are black.
+
+          f. Fourth and fifth segments of the first and second pair of
+              tarsi are black.
+
+            g. The yellow bands of the abdominal segments occupy a third
+                of the segment (fig. 165). G. MORSITANS Westw.
+
+            gg. The yellow band on each segment of the abdomen occupies
+                a sixth of the segment. G. LONGIPALPIS Wied.
+
+          ff. Tarsi of the first and second pairs of legs wholly yellow.
+              _G. pallidipes_ Austen
+
+    cc. Rays of the arista not plumose; only one or two sternopleurals;
+        base of the media not strongly bowed down; apical cell opens at
+        or very near the apex of the wing.
+
+      d. Vein R_{4+5} without setæ at the base; palpi about as long as
+          the proboscis.
+
+        e. Arista pectinate (i.e. rays on one side only), the rays often
+            undulate; two yellow sternopleurals often difficult to
+            detect; vein M_{1+2} only slightly bent, the apical cell
+            hence wide open. The horn fly, H. IRRITANS (= _Lyperosia
+            serrata_) and related species. Widely distributed (figs.
+            167, 168). HÆMATOBIA R. D. not B. B.
+
+[Illustration: 165. Glossina morsitans. (×4.) After Austen.]
+
+        ee. Arista also with rays below; vein M_{1+2} more strongly
+            bent, the apical cell hence less widely open.
+
+          f. Palpi strongly spatulate at the tips, lower rays of the
+              arista about six in number, B. SANGUINOLENTUS. South Asia.
+              BDELLOLARYNX Austen
+
+          ff. Palpi feebly spatulate; apical cell of the wing narrowly
+              open slightly before the tip; sternopleurals black,
+              anterior bristle sometimes absent. H. ATRIPALPIS. Europe.
+              HÆMATOBOSCA Bezzi
+
+      dd. Vein R_{4+5} with setæ at the base.[L]
+
+        e. Veins R_1 and R_{4+5} with setæ at the base; two equally
+            prominent sternopleural macrochætæ; arista with rays both
+            above and below; palpi as long as the proboscis; apical cell
+            of the wing wide open. L. TIBIALIS. (_Hæmatobia_ B. B. not
+            R. D.). LYPEROSIOPS Town.
+
+        ee. Only vein R_{4+5} with basal setæ; anterior sternopleural
+            macrochæta wanting; arista pectinate.
+
+          f. Palpi as long as the proboscis, the latter stout, with
+              fleshy terminal labellæ; apical cell narrowly open;
+              sternopleural macrochætæ black. S. MACULOSA from Africa
+              and related species from Asia. STYGEROMYIA Austen
+
+          ff. Palpi much shorter than the proboscis, the latter pointed
+              at the apex, without fleshy labellæ; apical cell of the
+              wing wide open. S. CALCITRANS, the stable fly and related
+              species. Widely distributed in both hemispheres (fig.
+              110). STOMOXYS Geof.
+
+aa. Proboscis neither slender nor elongate, the labellæ fleshy and not
+    adapted for piercing.
+
+  b. Hypopleuræ without a vertical row of macrochætæ. MUSCINÆ
+
+    c. Arista bare; distal portion of M_{1+2} broadly curved at the end;
+        hypopleuræ with a sparse cluster of fine hairs. _S.
+        braziliana_, Southern States and southward. _Synthesiomyia_ B.
+        B.
+
+    cc. Arista pectinate or plumose.
+
+      d. Arista pectinate. _H. vittigera_, with the posterior half of
+          the abdomen metallic blue. Mexico. _Hemichlora_ V. d. W.
+
+      dd. Arista plumose.
+
+        e. Middle tibia with one or more prominent setæ on the inner
+            (flexor) surface beyond the middle, or inner surface very
+            hairy.
+
+          f. R_1 ends distad of the m-cu crossvein; M_{1+2} with a broad
+              curve near its apical end. (= _Neomesembrina_ Schnabl. =
+              _Metamesembrina_ Town). _M. meridiana._ Europe.
+              _Mesembrina_ Meigen
+
+          ff. R_1 ends proximad of the m-cu crossvein.
+
+            g. Eyes pilose, sometimes sparsely in the female.
+
+              h. Female with two or three stout orbital setæ; the hind
+                  metatarsus of the male thickened below at the base and
+                  penicillate. _D. pratorum._ Europe. _Dasyphora_ R.
+                  D.[M]
+
+              hh. Neither sex with orbital setæ.
+
+                i. Abdomen without macrochætæ; arista plumose. _C.
+                    asiatica._ Eastern Hemisphere. _Cryptolucilia_ B. B.
+
+                ii. Abdomen with strong macrochætæ; arista very
+                    short-plumose, nearly bare. _B. tachinina._ Brazil.
+                    _Reinwardtia_ B. B.
+
+            gg. Eyes bare.
+
+              h. Body densely pilose; thoracic macrochætæ wanting;
+                  middle tibiæ much elongate and bent; last section of
+                  M_{1+2} with a gentle curve. H. (_Mesembrina_)
+                  _mystacea, et al._, Europe and _H. solitaria_, N.
+                  America. _Hypodermodes_ Town.
+
+              hh. Body not densely pilose.
+
+                i. Dorsocentrals six; last section of M_{1+2} with a
+                    gentle curve.
+
+                  j. Inner dorsocentrals ("acrostichals") wanting;
+                      sternopleurals arranged 1:3. _P. cyanicolor_,
+                      _cadaverina_, etc. Europe and America _Pyrellia_
+                      R. D.
+
+                  jj. Inner dorsocentrals ("acrostichals") present;
+                      sternopleurals arranged 1:2. E. _latreillii._
+                      North America. _Eumesembrina_ Town.
+
+                ii. Dorsocentrals five; inner dorsocentrals present;
+                    last section of M_{1+2} with a rounded angle;
+                    sternopleurals arranged 1:2. _P. cornicina_ Europe
+                    and America. (_Pseudopyrellia_ Girsch.) _Orthellia_
+                    R. D.
+
+        ee. Middle tibia without a prominent bristle on the inner
+            surface beyond the middle.
+
+[Illustration: 166. Pycnosoma marginale. (×4.) After Graham-Smith.]
+
+          f. Squamula thoracalis broadened mesad and caudad as far as
+              the scutellum.
+
+            g. Sternopleural macrochætæ arranged in an equilateral
+                triangle; front of both sexes broad; genæ bare;
+                dorsocentrals six, small; wing not rilled. (To
+                COENOSINÆ). _Atherigona_ Rdi.
+
+            gg. Sternopleural macrochætæ when three are present,
+                arranged in a right triangle.
+
+              h. Last section of M_{1+2} with a more or less rounded
+                  angle (fig. 163l).
+
+                i. Eyes of the male pilose or pubescent, of the female
+                    nearly bare; m-cu crossvein usually at or proximad
+                    of the mid-distance between the r-m crossvein and
+                    the bend of M_{1+2}. P. (= _Placomyia_ R. D.)
+                    _vitripennis_. _Plaxemyia_ R. D.
+
+                ii. Eyes bare; the m-cu crossvein always nearer to the
+                    bend of M_{1+2} than to the r-m crossvein.
+
+                  j. Apex of the proboscis when extended reveals a
+                      circlet of stout chitinous teeth. P. INSIGNIS
+                      Austen, of India, bites both man and animals. (=
+                      _Pristirhynchomyia_.) PHILÆMATOMYIA Austen
+
+                  jj. Apex of the proboscis without black teeth.
+
+                    k. Eyes of male separated by a distance equal to a
+                        fourth the width of the head. House or typhoid
+                        fly. M. DOMESTICA L. Widely distributed. MUSCA
+                        L.
+
+                    kk. Eyes of the male contiguous. E. CORVINA. Europe.
+                        EUMUSCA Town
+
+              hh. Last section of M_{1+2} with a gentle curve (fig.
+                  102).
+
+                i. Eyes pilose.
+
+                  j. Claws in the male somewhat elongated; no orbitals
+                      in either sex; antennæ separated at the base by a
+                      flat carina; abdomen marked with red or yellow.
+                      _G. maculata._ Europe and America. _Graphomyia_ R.
+                      D.
+
+                  jj. Claws short and equal in the two sexes; two or
+                      three stout orbital macrochætæ in the female; R_1
+                      scarcely produced beyond the r-m crossvein; eyes
+                      contiguous in the male. _P. obsoleta._ Brazil.
+                      _Phasiophana_ Br.
+
+                ii. Eyes bare; fronto-orbital macrochætæ in a double
+                    row, antennæ contiguous at the base.
+
+                  j. One or more pairs of well developed anterior inner
+                      dorsocentral (acrostichal) macrochætæ; seta on
+                      extensor surface of hind tibia. M. ASSIMILIS,
+                      STABULANS, etc. Europe and America. MUSCINA R. D.
+
+                  jj. Anterior inner dorsocentrals and the setæ; on the
+                      extensor surface of the hind tibia wanting. _M.
+                      micans_, etc. Europe and North America. _Morellia_
+                      R. D.
+
+          ff. Squamula thoracalis not broadened mesad and caudad, not
+              reaching the margin of the scutellum; macrochætæ on
+              extensor surface of the hind tibia wanting.
+
+            g. Eyes pubescent. _M. meditabunda._ Europe and America.
+                _Myiospila_ Rdi.
+
+            gg. Eyes bare; R_1 ends before the middle of the wing. A
+                number of species from the tropics of both hemispheres.
+                _Clinopera_ V. d. W.
+
+  bb. Hypopleuræ with a vertical row of macrochætæ.
+
+    c. Eyes pubescent.
+
+      d. R_1 ends about opposite the r-m crossvein; basal section of
+          R_{4+5} bristly nearly to the crossvein; _S. enigmatica_.
+          Africa. _Somalia_ Hough
+
+      dd. R_1 ends distad of the r-m crossvein.
+
+        e. Eastern hemisphere. Australasia. _N. ochracea_,
+             _dasypthalma._ _Neocalliphora_ Br.
+
+        ee. Western Hemisphere. _T. muscinum._ Mexico. _Tyreomma_ V. d.
+            W.
+
+    cc. Eyes bare.
+
+      d. The vibrissal angle situated at a noticeable distance above the
+          level of the margin of the mouth.
+
+        e. Sternopleural macrochætæ arranged in the order 1:1.
+
+          f. Genæ with microchætæ.
+
+            g. Body grayish, with depressed yellow woolly hair among the
+                macrochætæ; wings folded longitudinally over the body
+                when at rest. Cluster flies. _P. rudis_ and related
+                species, widely distributed. _Pollenia_ R. D.[N]
+
+            gg. Body metallic blue or green. Eastern Hemisphere.
+
+              h. Vibrissal angle placed very high above the oral margin;
+                  a carina between the antennæ; outer posthumeral
+                  wanting; anterior intraalar present. _T. viridaurea_.
+                  Java. _Thelychæta_ Br.
+
+[Illustration: 167. Horn fly. (_a_) egg; (_b_) larva; (_c_) puparium;
+(_d_) adult. (×4). Bureau of Entomology]
+
+              hh. Vibrissal angle moderately high above the oral margin;
+                  carina small or wanting; no post humeral macrochæta;
+                  lower squamæ hairy above. (= _Paracompsomyia_ Hough)
+                  (fig. 166). _Pycnosoma_ Br.
+
+          ff. Genæ bare. _S. terminata_. Eastern Hemisphere
+              _Strongyloneura_ Bigot
+
+        ee. Sternopleurals arranged 2:1.
+
+          f. Body metallic green or blue, with gray stripes; genæ hairy
+              to the lower margin; post humerals often wanting; lower
+              squamæ bare above. (= _Compsomyia_ Rdi.). CHRYSOMYIA R. D.
+
+            g. With one or two orbitals; height of bucca less than half
+                the height of the eye. South and east U. S. (fig. 107).
+                C. MARCELLARIA
+
+            gg. No orbitals; height of bucca about a third less than
+                height of eye. West U. S. _C. wheeleri_ Hough
+
+          ff. Body black or sordidly metallic greenish gray, usually
+              yellow pollinose or variegate; genæ at most hairy above.
+              _N. stygia_. Eastern Hemisphere. _Neopollenia_ Br.
+
+      dd. Vibrissal angle situated nearly on a level of the oral margin.
+
+        e. Species wholly blackish, bluish, or greenish metallic in
+            color.
+
+          f. First section of R_{4+5} with at most three or four small
+              bristles at the immediate base.
+
+            g. The bend of M_{1+2} a gentle curve; costal spine present;
+                cell R_5 closed, ending before the apex of the wing. _S.
+                cuprina._ Java. _Synamphoneura_ Bigot
+
+            gg. Bend of M_{1+2} angular; or the insect differs in other
+                characters; dorsal surface of the squamula thoracalis
+                hairy (except in _Melinda_); arista plumose only on the
+                basal two-thirds (except usually in _Calliphora_ and
+                _Eucalliphora_).
+
+[Illustration: 168. Head of horn-fly (Lyperosia irritans); (_a_) female;
+(_b_) male; (_c_) lateral aspect of female. Bureau of Entomology]
+
+              h. Arista plumose only on the basal two-thirds.
+
+                i. Base of the antennæ ventrad of the middle of the eye;
+                    eyes of the male nearly contiguous; genæ hairy;
+                    second abdominal segment with median marginal
+                    macrochætæ; two, rarely three, postsutural intraalar
+                    macrochætæ.
+
+                  j. Squamula thoracalis dorsally with long black hairs;
+                      male hypopygium two-segmented, large, projecting;
+                      claws and pulvilli of the male elongate; three
+                      strong sternopleural macrochætæ; genæ at least
+                      half the width of the eye; buccæ (cheeks) half the
+                      height of the eyes; oviviparous. _O. sepulcralis._
+                      Europe. _Onesia_ R. D.
+
+                  jj. Dorsal surface of the squamula thoracalis bare;
+                      male hypopygium small, scarcely projecting below;
+                      claws and pulvilli not elongate; two stout
+                      sternopleural macrochætæ, sometimes with a
+                      delicate one below the anterior; genæ nearly
+                      linear in the male; buccæ about a third of the eye
+                      height; oviparous. _M. cærulea_. Europe.
+                      _Melinda_. R. D.
+
+[Illustration: 169. Lateral and dorsal aspects of the thorax, and
+frontal aspect of the head of a muscoidean fly, with designations of the
+parts commonly used in taxonomic work.]
+
+                ii. Base of the antennæ dorsad of the middle of the eye;
+                    eyes of both sexes distinctly separated; dorsal
+                    surface of the squamula thoracalis with black hairs;
+                    two postsutural intraalar macrochætæ.
+
+                  j. Hypopygium of the male large, with a pair of
+                      slightly curved forceps whose ends are concealed
+                      in a longitudinal slit in the fifth ventral
+                      sclerite; third posterior inner dorso-central
+                      (acrostichal) macrochætæ absent; anterior
+                      intraalar rarely present; abdomen usually not
+                      pollinose; the second segment without median
+                      marginal macrochætæ; face yellow. _C. mortuorum_,
+                      _cadaverina_, and related species. Both
+                      hemispheres. _Cynomyia_ R. D.[O]
+
+[Illustration: 170. Sepsis violacea; puparium and adult. (See page 297.)
+After Howard.]
+
+                  jj. Three pairs of posterior inner dorsocentrals
+                      (acrostichals) present; second abdominal segment
+                      with a row of marginal macrochætæ; genæ hairy, at
+                      least above.
+
+                    k. Hypopygium of the male with a projecting style.
+                        _S. stylifera_. Europe. _Steringomyia_ Pok.
+
+
+                    kk. Hypopygium of the male without style. _A.
+                        stelviana_ B. B. _Acrophaga_ B. B.
+
+              hh. Arista usually plumose nearly to the tip; posterior
+                  dorsocentrals and inner dorsocentrals (acrostichals)
+                  well developed; dorsal surface of the squamula
+                  thoracalis hairy; abdomen metallic and usually
+                  pollinose; genæ hairy.
+
+                i. With one pair of ocellar macrochætæ. C. VOMITORIA,
+                    ERYTHROCEPHALA, VIRIDESCENS, and related species.
+                    Both hemispheres. CALLIPHORA R. D.
+
+                ii. With two strong pairs of ocellar macrochætæ. _E.
+                    latifrons._ Pacific slope of the U. S.
+                    _Eucalliphora_ Town.
+
+          ff. First section of R_{4+5} bristly near or quite half way to
+              the small crossvein; dorsal surface of the squamula
+              thoracalis is bare; the hypopygium of the male is
+              inconspicuous.
+
+            g. Genæ bare; posterior inner and outer dorsocentrals
+                distinct and well developed. _L. cæsar_, _sericata_,
+                _sylvarum_, and related species. Widely distributed in
+                both hemispheres (fig. 103). LUCILIA R. D.
+
+            gg. Genæ with microchætæ, at least down to the level of the
+                base of the arista.
+
+              h. Mesonotum flattened behind the transverse suture.
+
+                i. Posterior dorsocentrals inconstant and unequally
+                    developed; one pair of posterior inner
+                    dorsocentrals. _P. terrænovæ._ North America.
+                    _Protophormia_ Town.
+
+                ii. Posterior dorsocentrals well developed, the inner
+                    dorsocentrals (acrostichals) unequally developed.
+                    _P. azurea_, _chrysorrhoea_, etc. Europe and America.
+                    _Protocalliphora_ Hough
+
+              hh. Mesonotum not flattened behind the transverse suture;
+                  posterior inner and outer dorsocentrals inconstant and
+                  unequally developed. _P. regina._ Europe and America.
+                  _Phormia_ R. D.
+
+        ee. Species more or less rufous or yellow in color.
+
+          f. Anterior dorsocentrals wanting; first section of the
+              R_{4+5} at most only bristly at the base, bend near apex
+              of M_{1+2} rectangular, R_1 ends over the crossvein;
+              fronto-orbital macrochæta absent; eyes of the male
+              contiguous. _C. semiviridis._ Mexico. _Chloroprocta_
+              V. d. W
+
+          ff. With another combination of characters.
+
+            g. Body robust, of large size, abdomen elongate, not round;
+                genæ with several ranges of microchætæ; vibrissal ridges
+                strongly convergent; abdomen with well developed
+                macrochætæ; costal spine usually absent; eyes of the
+                male widely separated.
+
+[Illustration: 171. Stigmata of the larvæ of Muscoidea. Third instar.
+(_a_) Cynomyia cadaverina; (_b_) Phormia regina; (_c_) Chrysomyia
+macellaria; (_d_) Musca domestica; (_e_) Sarcophaga sp.; (_f_) Oestris
+ovis; (_g_) Gastrophilus equi; (_h_) Sarcophaga sp.; (_i_) Pegomyia
+vicina; (_j_) Protocalliphora azurea; (_k_) Hypoderma lineata; (_l_)
+Muscina stabulans. Magnification for f, g, and k, ×25; all others, ×
+50.]
+
+              h. Peristome broad, pteropleural macrochætæ distinct; one
+                  or two sternopleurals; in the female a single orbital
+                  macrochæta; last abdominal segment without discal
+                  macrochætæ; hypopygial processes of the male with a
+                  long stylet; second abdominal segment of the female
+                  sometimes much elongate. A. LUTEOLA (fig. 86).
+                  Africa. The sub-genus _Choeromyia_ Roub. is included
+                  here. AUCHMEROMYIA B. B.
+
+              hh. Peristome narrow; no pteropleurals, two
+                  sternopleurals; two orbitals in the female; second
+                  segment not elongate; the fourth with two well
+                  developed discal macrochætæ. B. DEPRESSA. Africa.
+                  BENGALIA R. D
+
+            gg. With another combination of characters.
+
+              h. Costal spine present; body in part black; antennæ
+                  noticeably shorter than the epistome, inserted above
+                  the middle of the eye and separated from each other by
+                  a carina; abdominal segments with marginal macrochætæ;
+                  sternopleurals 2:1 or 1:1. _Paratricyclea_ Villen.
+
+              hh. Costal spine not distinct, or if present, insect
+                  otherwise different.
+
+                i. Genæ with several ranges of microchætæ; vibrissal
+                    ridges strongly converging; peristome broad; arista
+                    moderately plumose; sternopleurals usually 1:1;
+                    color entirely testaceous. C. ANTHROPOPHAGA (fig.
+                    87) and GRUNBERGI. Africa. CORDYLOBIA Grünb.
+
+                ii. Genæ bare or with but one range of setæ; vibrissal
+                    ridges less converging; peristome narrow; arista
+                    long plumose.
+
+                  j. Genæ with a single row of microchætæ.
+
+                    k. Sternopleurals 2:1; color entirely testaceous.
+                        _Ochromyia_ Macq.[P]
+
+                    kk. Sternopleurals 1:1. _P. varia_ Hough. Africa.
+                        _Parochromyia_ Hough
+
+                  jj. Genæ bare.
+
+                    k. Basal section of R_{4+5} bristly only at the
+                        immediate base, distally M_{1+2} with a broad
+                        curve; distal portion of the abdomen metallic;
+                        sternopleurals usually 1:1, rarely 2:1. _M.
+                        æneiventris_ Wd. Tropic America.
+                        _Mesembrinella._ G. T.
+
+                    kk. R_{4+5} bristly at least nearly half way to the
+                        small crossvein; sternopleurals 1:1.
+
+                      l. Macrochætæ of the abdomen marginal; neither sex
+                          with orbitals; no carina between the base of
+                          the antennæ; three pairs of presutural inner
+                          dorsocentrals. Eastern hemisphere. _T.
+                          ferruginea._ _Tricyclea V. d. W_. (=
+                          _Zonochroa_ B. B. according to Villeneuve
+                          1914).
+
+                      ll. Abdomen without macrochætæ; wing usually with
+                          a marginal streak and gray markings. Brazil.
+                          Hemilucilia B. B.
+
+[Illustration: 172. Left hand stigmata of the larvæ of muscoidea. Third
+instar. (_a_) Lucilia cæsar; (_b_) Calliphora vomitoria; (_c_) Stomoxys
+calcitrans; (_d_) Orthellia cornicina; (_e_) Pyrellia cadavarina;
+(_f_) Hæmatobia irritans; (_g_) Mesembrina mystacea; (_h_) Mesembrina
+meridiana; (_i_) Myospila meditabunda; (_j_) Mydæa urbana; (_k_)
+Polietes albolineata; (_l_) Polietes lardaria; (_m_) Morellia hortorum;
+(_n_) Hydrotæa dentipes; (_o_) Hebecnema umbratica; (_p_) H. vespertina;
+(_q_) Limnophora septemnotata; (_r_) Muscina stabulans. (_a_ and _b_)
+after MacGregor; (_d_) after Banks; all others after Portchinsky.
+Magnification varies. The relative distance to the median line is
+indicated in each figure.]
+
+
+SIPHONAPTERA. Fleas
+
+Adapted from a table published by Oudemans.
+
+a. Elongated fleas, with jointed (articulated) head, with combs
+    (ctenidia) on head and thorax; with long, oval, free-jointed
+    flagellum of the antenna (fig. 92d). Suborder FRACTICIPATA
+
+  b. With ctenidia in front of the antennæ and on the genæ (cheeks);
+      maxillæ with acute apices; labial palpi five-segmented,
+      symmetrical; eyes poorly developed or wanting. On rodents.
+      HYSTRICHOPSYLLIDÆ
+
+    c. Abdominal segments without ctenidia.
+
+      d. Post-tibial spines in pairs and not in a very close set row;
+          head with ctenidia. _Ctenophthalmus_ Kol.
+
+      dd. Post-tibial spines mostly single and in a close set row.
+          _Ctenopsyllus_ and _Leptopsyllus_. The last genus has recently
+          been erected for _L. musculi_, a widely distributed species
+          occurring on rats and mice.
+
+    cc. Abdominal segments with one or more ctenidia; post-tibial
+        spines in numerous, short, close-set transverse rows on
+        posterior border with about four spines in each row. _H.
+        americana._ _Hystrichopsylla_ Taschenb.
+
+  bb. With only two pairs of subfrontal ctenidia; labial palpi
+      five-segmented, symmetrical; eyes vestigial or wanting. On bats.
+      (= ISCHNOPSYLLIDÆ). NYCTERIDIPSYLLIDÆ
+
+    With more or less blunt maxilla; all tibiæ with notch; a single
+        antepygidial bristle; metepimeron without ctenidium. _N.
+        crosbyi_ from Missouri was found on bats. Rothschild suggests
+        that this is probably the same as _N. insignis_. (=
+        _Ischnopsyllus_ = _Ceratopsyllus_), _Nycteridiphilus_
+
+aa. Head not jointed, i.e. the segments coalescent, traces of the
+    segmentation still being visible in the presence of the vertex
+    tubercle, the falx (sickle-shaped process), and a suture. Suborder
+    INTEGRICIPITA
+
+  b. Flagellum of the antennæ long and oval.
+
+    c. Usually elongate fleas, with a free-segmented flagellum of the
+        antenna; thorax not shorter than the head, longer than the first
+        tergite.
+
+      d. Genæ of the head and the pronotum with ctenidia. NEOPSYLLIDÆ
+
+        e. Labial palpi four or five-segmented; symmetrical; hind coxæ
+            with patch of spines inside; row of six spatulate spines on
+            each side in front of the antennæ. _C. ornate_ found on a
+            California mole. _Corypsylla_
+
+        ee. Labial palpi two-segmented, transparent, membranous. On
+            hares. _Spilopsyllus_ Baker
+
+      dd. No ctenidium on the head.
+
+        e. Pronotum with ctenidium. DOLICHOPSYLLIDÆ
+
+          f. Labial palpi five-segmented, symmetrical.
+
+            g. Antepygidial bristles one to three; eyes present.
+
+              h. Inner side of hind coxæ distally with a comb of minute
+                  teeth; falx present. On rodents and carnivores.
+                  _Odontopsyllus_ Baker
+
+              hh. Inner side of hind coxæ without comb or teeth. Many
+                  North American species on rodents. CERATOPHYLLUS
+                  Curtis
+
+            gg. Antepygidial bristles five on each side; eyes absent;
+                suture white. _D. stylosus_ on rodents. _Dolichopsyllus_
+                Baker
+
+          ff. Labial palpi four or five-segmented; asymmetrical
+              (membranous behind), apex acute. _Hoplopsyllus anomalus_
+              found on Spermophiles in Colorado. HOPLOPSYLLIDÆ
+
+        ee. Pronotum without ctenidium. _Anomiopsyllus californicus_ and
+            _nudatus_ on rodents. ANOMIOPSYLLIDÆ
+
+    cc. Very short fleas; flagellum of the antenna with pseudo-segments
+        coalescent; thorax much shorter than the head and than the first
+        tergite. HECTOPSYLLIDÆ
+
+      Flagellum of the antenna with six coalescent pseudo-segments;
+          maxilla blunt. The chigger on man (fig. 93). D. PENETRANS. (=
+          RHYNCHOPRION = SARCOPSYLLA) DERMATOPHILUS Guérin
+
+  bb. Flagellum short, round, free portion of the first segment shaped
+      like a mandolin.
+
+    c. Thorax not shorter than the head, longer than the first tergite;
+        flagellum either with free segments or in part with the segments
+        coalescent.
+
+      d. Head and pronotum with ctenidium; labial palpi asymmetrical.
+          ARCHÆOPSYLLIDÆ
+
+        With four subfrontal, four genal, and one angular ctenidia.
+            Widely distributed. CTENOCEPHALUS Kol.
+
+        e. Head rounded in front (fig. 92a). Dog flea. C. CANIS
+
+        ee. Head long and flat (fig. 92b). Cat flea. C. FELIS
+
+      dd. Neither head nor pronotum with ctenidium. Labial palpi
+          asymmetrical, membranous behind. PULICIDÆ
+
+        e. Mesosternite narrow, without internal rod-like thickening
+            from the insertion of the coxæ upwards. Human flea, etc.
+            PULEX L.
+
+        ee. Mesosternite broad with a rod-like internal thickening from
+            the insertion of the coxæ upwards (fig. 89). X.
+            (LOEMOPSYLLA) CHEOPIS, plague or rat flea. XENOPSYLLA
+
+    cc. Thorax much shorter than the head and than the first tergite.
+        ECHIDNOPHAGIDÆ. E. GALLINACEA, the hen flea also attacks man
+        (fig. 96). (= ARGOPSYLLA = XESTOPSYLLA) ECHIDNOPHAGA Olliff.
+
+
+FOOTNOTES:
+
+[E] Adapted from Banks, Nuttall, Warburton, Stiles, _et al._
+
+[F] Dr. C. W. Stiles considers the species which is responsible for
+spotted fever distinct from the _venustus_ of Banks, separating it as
+follows:
+
+Goblet cells about 75 in the male or 105 in the female. Texas. _D.
+venustus._
+
+Goblet cells 157 in the male, or 120 in the female; stigmal plate shaped
+as shown in the figure (figs. 150 a, b). Montana, etc. D. ANDERSONI.
+
+[G] Professor C. R. Crosby who has been working upon certain capsids
+states that he and his assistant have been bitten by LYGUS PRATENSIS,
+the tarnished plant bug, by CHLAMYDATUS ASSOCIATUS and by ORTHOTYLUS
+FLAVOSPARSUS, though without serious results.
+
+[H] Species marked with an * are known to transmit malaria. Species
+found only in tropical North America and not known to carry malaria have
+been omitted from this table, but all found in the United States are
+included.
+
+[I] This table to the North American genera of the Tabanidæ is adapted
+from one given by Miss Ricardo.
+
+[J] The classification of the Muscoidea as set forth by Schiner and
+other earlier writers has long been followed, although it is not
+satisfactory, being admittedly more or less artificial. Within the last
+two or three decades several schemes have been advanced, that of Brauer
+and Bergenstamm and of Girschner, with the modifications of Schnabl and
+Dziedzicki having obtained most favor in Europe. Townsend, in 1908,
+proposed a system which differs from Girschner's in some respects, but
+unfortunately it has not yet been published in sufficient detail to
+permit us to adopt it. From considerations of expediency we use here the
+arrangement given in Aldrich's Catalogue of North American Diptera,
+though we have drawn very freely upon Girschner's most excellent paper
+for taxonomic characters to separate the various groups.
+
+It may sometimes be found that a species does not agree in all the
+characters with the synopsis; in this case it must be placed in the
+group with which it has the most characters in common.
+
+[K] There are several genera of flies of the family _Cordyluridæ_; (i.e.
+_Acalyptratæ_) which might be placed with the _Anthomyiidæ_ (i.e.
+_Calyptratæ_), owing to the relatively large size of their squamæ. As
+there is no single character which will satisfactorily separate all
+doubtful genera of these two groups we must arbitrarily fix the limits.
+In general those forms on the border line having a costal spine, or
+lower squama larger than the upper, or the lower surface of the
+scutellum more or less pubescent, or the eyes of the male nearly or
+quite contiguous, or the eyes hairy, or the frontal setæ decussate in
+the female; or any combination of these characters may at once be placed
+with the _Anthomyiidæ_. Those forms which lack these characteristics and
+have at least six abdominal segments (the first and second segments
+usually being more or less coalescent) are placed with the Acalyptrates.
+There are other acalyptrates with squamæ of moderate size which have
+either no vibrissæ, or have the subcosta either wholly lacking or
+coalescent in large part with R_1 or have spotted wings; they, therefore
+will not be confused with the calyptrates.
+
+[L] _Pachymyia_ Macq. is closely related to _Stomoxys_. It differs in
+having the arista rayed both above and below. _P. vexans_, Brazil.
+
+[M] The genus _Eudasyphora_ Town. has recently been erected to contain
+_D. lasiophthalma_.
+
+[N] _Nitellia_, usually included in this genus has the apical cell
+petiolate. _Apollenia_ Bezzi, has recently been separated from
+_Pollenia_ to contain the species _P. nudiuscula_. Both genera belong to
+the Eastern hemisphere.
+
+[O] The following three genera are not sufficiently well defined to
+place in this synopsis. In color and structural characters they are
+closely related to _Cynomyia_ from which they may be distinguished as
+follows. _Catapicephala_ Macq., represented by the species _C.
+splendens_ from Java, has the setæ on the facial ridges rising to the
+base of the antennæ and has median marginal macrochætæ on the abdominal
+segments two to four: _Blepharicnema_ Macq., represented by _B.
+splendens_ from Venezuela has bare genæ, oral setæ not ascending; tibiæ
+villose; claws short in both sexes; _Sarconesia_ Bigot with the species
+_S. chlorogaster_ from Chile, setose genæ; legs slender, not villose;
+claws of the male elongate.
+
+[P] _Plinthomyia_ Rdi. and _Hemigymnochæta_ Corti are related to
+_Ochromyia_, though too briefly described to place in the key.
+
+
+
+
+APPENDIX
+
+HYDROCYANIC ACID GAS AGAINST HOUSEHOLD INSECTS
+
+
+The following directions for fumigating with hydrocyanic acid
+gas are taken from Professor Herrick's circular published by the
+Cornell Reading Course:
+
+Hydrocyanic acid gas has been used successfully against household
+insects and will probably be used more and more in the future.
+It is particularly effective against bed-bugs, and cockroaches, but
+because _it is such a deadly poison it must be used very carefully_.
+
+The gas is generated from the salt potassium cyanid, by treating
+it with sulfuric acid diluted with water. Potassium cyanid is a
+most poisonous substance and the gas emanating from it is also
+deadly to most, if not all, forms of animal life. The greatest care
+must always be exercised in fumigating houses or rooms in buildings
+that are occupied. Before fumigation a house should be vacated.
+It is not necessary to move furniture or belongings except brass or
+nickel objects, which may be somewhat tarnished, and butter, milk,
+and other larder supplies that are likely to absorb gas. If the nickel
+and brass fixtures or objects are carefully covered with blankets
+they will usually be sufficiently protected.
+
+There may be danger in fumigating one house in a solid row of
+houses if there is a crack in the walls through which the gas may find
+its way. It also follows that the fumigation of one room in a house
+may endanger the occupants of an adjoining room if the walls between
+the two rooms are not perfectly tight. It is necessary to keep
+all these points in mind and to do the work deliberately and thoughtfully.
+The writer has fumigated a large college dormitory of 253
+rooms, once a year for several years, without the slightest accident
+of any kind. In order to fumigate this building about 340 pounds
+of cyanid and the same amount of sulfuric acid were used each time.
+In addition to this, the writer has fumigated single rooms and smaller
+houses with the gas. In one instance the generating jars were too
+small; the liquid boiled over and injured the floors and the rugs.
+Such an accident should be avoided by the use of large jars and by
+placing old rugs or a quantity of newspapers beneath the jars.
+
+
+THE PROPORTIONS OF INGREDIENTS
+
+Experiments and experience have shown that the potassium
+cyanid should be ninety-eight per cent pure in order to give satisfactory
+results. The purchaser should insist on the cyanid being of
+at least that purity, and it should be procurable at not more than
+forty cents per pound. The crude form of sulfuric acid may be used.
+It is a thickish, brown liquid and should not cost more than four or
+five cents a pound. If a room is made tight, one ounce of cyanid for
+every one hundred cubic feet of space has been shown to be sufficient.
+It is combined with the acid and water in the following proportions:
+
+  Potassium cyanid                       1 ounce
+  Commercial sulfuric acid               1 fluid ounce
+  Water                                  3 fluid ounces
+
+
+A SINGLE ROOM AS AN EXAMPLE
+
+Suppose a room to be 12 by 15 by 8 feet. It will contain 12 × 15 × 8, or
+1440 cubic feet. For convenience the writer always works on the basis of
+complete hundreds; in this case he would work on the basis of 1500 cubic
+feet, and thus be sure to have enough. The foregoing room, then, would
+require 15 ounces of cyanid, 15 ounces of sulfuric acid, and 45 ounces
+of water. The room should be made as tight as possible by stopping all
+the larger openings, such as fireplaces and chimney flues, with old rags
+or blankets. Cracks about windows or in other places should be sealed
+with narrow strips of newspaper well soaked in water. Strips of
+newspaper two or three inches wide that have been thoroughly soaked in
+water may be applied quickly and effectively over the cracks around the
+window sash and elsewhere. Such strips will stick closely for several
+hours and may be easily removed at the conclusion of the work.
+
+While the room is being made tight, the ingredients should be measured
+according to the formula already given. The water should be measured and
+_poured first_ into a stone jar for holding at least two gallons. The
+jar should be placed in the middle of the room, with an old rug or
+several newspapers under it in order to protect the floor.
+
+The required amount of sulfuric acid should then be poured rather slowly
+into the water. _This process must never be reversed; that is, the acid
+must never be poured into the jar first._ The cyanid should be weighed
+and put into a paper bag beside the jar. All hats, coats, or other
+articles that will be needed before the work is over should be removed
+from the room. When everything is ready the operator should drop the bag
+of cyanid gently into the jar, holding his breath, and should walk
+quickly out of the room. The steam-like gas does not rise immediately
+under these conditions, and ample time is given for the operator to walk
+out and shut the door. If preferred, however, the paper bag may be
+suspended by a string passing through a screw eye in the ceiling and
+then through the keyhole of the door. In this case the bag may be
+lowered from the outside after the operator has left the room and closed
+the door.
+
+The writer has most often started the fumigation toward evening and left
+it going all night, opening the doors in the morning. The work can be
+done, however, at any time during the day and should extend over a
+period of five or six hours at least. It is said that better results
+will be obtained in a temperature of 70° F., or above, than at a lower
+degree.
+
+At the close of the operation the windows and doors may be opened from
+the outside. In the course of two or three hours the gas should be
+dissipated enough to allow a person to enter the room without danger.
+The odor of the gas is like that of peach kernels and is easily
+recognized. The room should not be occupied until the odor has
+disappeared.
+
+
+FUMIGATING A LARGE HOUSE
+
+The fumigation of a large house is merely a repetition, in each room and
+hall, of the operations already described for a single room. All the
+rooms should be made tight, and the proper quantities of water and
+sulfuric acid should be measured and poured into jars placed in each
+room with the cyanid in bags besides the jars. When all is ready, the
+operator should _go to the top floor and work downward_ because the gas
+is lighter than air and tends to rise.
+
+
+PRECAUTIONS
+
+The cyanid should be broken up into small pieces not larger than small
+eggs. This can best be done on a cement or brick pavement. It would be
+advantageous to wear gloves in order to protect the hands, although the
+writer has broken many pounds of cyanid without any protection on the
+hands. Wash the hands thoroughly at frequent intervals in order to
+remove the cyanid.
+
+The operations of the work must be carried out according to directions.
+
+The work should be done by a calm, thoughtful and careful person--best
+by one who has had some experience.
+
+Conspicuous notices of what has been done should be placed on the doors,
+and the doors should be locked so that no one can stray into the rooms.
+
+The gas is lighter than air, therefore one should always begin in the
+rooms at the top of the house and work down.
+
+After fumigation is over the contents of the jar should be emptied into
+the sewer or some other safe place. The jars should be washed thoroughly
+before they are used again.
+
+_It must be remembered that cyanid is a deadly poison_; but it is very
+efficient against household insects, if carefully used, and is not
+particularly dangerous when properly handled.
+
+
+LESIONS PRODUCED BY THE BITE OF THE BLACK-FLY
+
+While this text was in press there came to hand an important paper
+presenting a phase of the subject of black fly injury so different from
+others heretofore given that we deem it expedient to reproduce here the
+author's summary. The paper was published in _The Journal of Cutaneous
+Diseases_, for November and December, 1914, under the title of "A
+Clinical, Pathological and Experimental Study of the Lesions Produced by
+the Bite of the Black Fly (_Simulium venustum_)," by Dr. John Hinchman
+Stokes, of the University of Michigan.
+
+
+RESUME AND DISCUSSION OF EXPERIMENTAL FINDINGS
+
+The principal positive result of the work has been the experimental
+reproduction of the lesion produced by the black-fly in characteristic
+histological detail by the use of preserved flies. The experimental
+lesions not only reproduced the pathological pictures, but followed a
+clinical course, which in local symptomatology especially, tallied
+closely with that of the bite. This the writer interprets as
+satisfactory evidence that the lesion is not produced by any living
+infective agent. The experiments performed do not identify the nature of
+the toxic agent. Tentatively they seem to bring out, however, the
+following characteristics.
+
+1. The product of alcoholic extraction of flies do not contain the toxic
+agent.
+
+2. The toxic agent is not inactivated by alcohol.
+
+3. The toxic agent is not destroyed by drying fixed flies.
+
+4. The toxic agent is not affected by glycerin, but is, if anything,
+more active in pastes made from the ground fly and glycerin, than in the
+ground flies as such.
+
+5. The toxic agent is rendered inactive or destroyed by hydrochloric
+acid in a concentration of 0.25%.
+
+6. The toxic agent is most abundant in the region of the anatomical
+structures connected with the biting and salivary apparatus (head and
+thorax).
+
+7. The toxic agent is not affected by a 0.5% solution of sodium
+bicarbonate.
+
+8. The toxic agent is not affected by exposure to dry heat at 100° C.
+for two hours.
+
+9. The toxic agent is destroyed or rendered inactive in alkaline
+solution by a typical hydrolytic ferment, pancreatin.
+
+10. Incomplete experimental evidence suggests that the activity of the
+toxic agent may be heightened by a possible lytic action of the blood
+serum of a sensitive individual, and that the sensitive serum itself may
+contain the toxic agent in solution.
+
+These results, as far as they go (omitting No. 10), accord with Langer's
+except on the point of alcoholic solubility and the effect of acids. The
+actual nature of the toxic agent in the black-fly is left a matter of
+speculation.
+
+The following working theories have suggested themselves to the writer.
+First, the toxin may be, as Langer believes in the case of the bee, an
+alkaloidal base, toxic as such, and neutralized after injection by
+antibodies produced for the occasion by the body. In such a case the
+view that a partial local fixation of the toxin occurs, which prevents
+its immediate diffusion, is acceptable. Through chemotactic action,
+special cells capable of breaking up the toxin into harmless elements
+are attracted to the scene. Their function may be, on the other hand, to
+neutralize directly, not by lysis. This would explain the rôle of the
+eosinophiles in the black-fly lesion. If their activities be essential
+to the destruction or neutralization of the toxin, one would expect them
+to be most numerous where there was least reaction. This would be at the
+site of a bite in an immune individual. A point of special interest for
+further investigation, would be the study of such a lesion.
+
+Second, it is conceivable that the injected saliva of the fly does not
+contain an agent toxic as such. It is possible, that like many foreign
+proteins, it only becomes toxic when broken down. The completeness and
+rapidity of the breaking down depends on the number of eosinophiles
+present. In such a case immunity should again be marked by intense
+eosinophilia.
+
+[Illustration: 173. Fifth day mature lesion. Lower power drawing showing
+papillary oedema and infiltrate in the region of the puncture. After Dr.
+J .H. Stokes]
+
+Third, lytic agents in the blood serum may play the chief rôle in the
+liberation of the toxic agent from its non-toxic combination. An immune
+individual would then be one whose immunity was not the positive one of
+antibody formation, but the negative immunity of failure to metabolize.
+An immune lesion in such a case might be conceived as presenting no
+eosinophilia, since no toxin is liberated. If the liberation of the
+toxin is dependent upon lytic agents present in the serum rather than in
+any cellular elements, a rational explanation would be available for the
+apparent results (subject to confirmation) of the experiment with
+sensitive and immune sera. In this experiment it will be recalled that
+the sensitive serum seemed to bring out the toxicity of the ground
+flies, and the serum itself seemed even to contain some of the dissolved
+or liberated toxin. The slowness with which a lesion develops in the
+case of the black-fly bite supports the view of the initial lack of
+toxicity of the injected material. The entire absence of early
+subjective symptoms, such as pain, burning, etc., is further evidence
+for this view. It would appear as if no reaction occurred until lysis of
+an originally non-toxic substance had begun. Regarding the toxin itself
+as the chemotactic agent which attracts eosinophiles, its liberation in
+the lytic process and diffusion through the blood stream attracts the
+cells in question to the point at which it is being liberated. Arriving
+upon the scene, these cells assist in its neutralization.
+
+The last view presented is the one to which the author inclines as the
+one which most adequately explains the phenomena.
+
+A fourth view is that the initial injection of a foreign protein by the
+fly (i.e., with the first bite) sensitizes the body to that protein. Its
+subsequent injection at any point in the skin gives rise to a local
+expression of systematic sensitization. Such local sensitization
+reactions have been described by Arthus and Breton, by Hamburger and
+Pollack and by Cowie. The description of such a lesion given by the
+first named authors, in the rabbit, however, does not suggest,
+histopathologically at least, a strong resemblance to that of the
+black-fly. Such an explanation of many insect urticariæ deserves further
+investigation, however, and may align them under cutaneous expressions
+of anaphylaxis to a foreign protein injected by the insect. Depending on
+the chemical nature of the protein injected, a specific chemotactic
+reaction like eosinophilia may or may not occur. Viewed in this light
+the development of immunity to insect bites assumes a place in the
+larger problem of anaphylaxis.
+
+[Illustration: 174. Experimental lesion produced from alcohol-fixed
+flies, dried and ground into a paste with glycerin. After Dr. J. H.
+Stokes]
+
+
+SUMMARY
+
+In order to bring the results of the foregoing studies together, the
+author appends the following résumé of the clinical data presented in
+the first paper.
+
+The black-fly, _Simulium venustum_, inflicts a painless bite, with
+ecchymosis and hæmorrhage at the site of puncture. A papulo-vesicular
+lesion upon an urticarial base slowly develops, the full course of the
+lesion occupying several days to several weeks. Marked differences in
+individual reaction occur, but the typical course involves four stages.
+These are, in chronological order, the papular stage, the vesicular or
+pseudovesicular, the mature vesico-papular or weeping papular stage and
+the stage of involution terminating in a scar. The papule develops in
+from 3 to 24 hours. The early pseudovesicle develops in 24 to 48 hours.
+The mature vesico-papular lesion develops by the third to fifth day and
+may last from a few days to three weeks. Involution is marked by
+cessation of oozing, subsidence of the papule and scar-like changes at
+the site of the lesion. The symptoms accompanying this cycle consist of
+severe localized or diffused pruritus, with some heat and burning in the
+earlier stages if the oedema is marked. The pruritus appears with the
+pseudovesicular stage and exhibits extraordinary persistence and a
+marked tendency to periodic spontaneous exacerbation. The flies tend to
+group their bites and confluence of the developing lesions in such cases
+may result in extensive oedema with the formation of oozing and
+crusted plaques. A special tendency on the part of the flies to attack
+the skin about the cheeks, eyes and the neck along the hair line and
+behind the ears, is noted. In these sites inflammation and oedema may
+be extreme.
+
+A distinctive satellite adenopathy of the cervical glands develops in
+the majority of susceptible persons within 48 hours after being bitten
+in the typical sites. This adenopathy is marked, discrete and painful,
+the glands often exquisitely tender on pressure. It subsides without
+suppuration.
+
+Immunity may be developed to all except the earliest manifestations, by
+repeated exposures. Such an immunity in natives of an infested locality
+is usually highly developed. There are also apparently seasonal
+variations in the virulence of the fly and variations in the reaction of
+the same individual to different bites.
+
+Constitutional effects were not observed but have been reported.
+
+
+
+
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+   Zeitung. xx, p. 28-33.
+
+HERMS, W. B. 1911. The housefly in its relation to public health. Cal.
+   Agric. Exp. Sta. Bul. 215, p. 511-548.
+
+---- 1913. Malaria: cause and control. 8^o. New York, Macmillan Co. (xi
+   + 163 p.).
+
+HERRICK, G. W. 1903. The relation of malaria to agriculture and other
+   industries of the South. Pop. Sci. Mo. lxii, p. 521-525.
+
+---- 1913. Household insects and methods of control. Cornell Reading
+   Course, (N. Y. State College of Agric.), iii, 47 p.
+
+---- 1914. Insects injurious to the household and annoying to man. 8vo.
+   New York, Macmillan Co. (xvii + 470).
+
+HEWITT, C. G. 1910. The house-fly. A study of its structure,
+   development, bionomics, and economy. 8vo. Manchester Univ. Press.
+   (xiv + 196 p.).
+
+---- 1912. _Fannia_ (_Homalomyia_) _canicularis_ Linn. and _F. scalaris_
+   Fab. Parasitology, v. p. 161-174.
+
+HEYMONS, R. 1901. Biologische Beobachtungen an asiatischen Solifugen,
+   nebst Beiträge zur Systematik derselben. Abl. Ak. Berlin, 1901, Anh.
+   i, 1-65 p.
+
+HIGGINS, F. W. 1891. Dipterous larvæ vomited by a child. Insect Life,
+   Washington. iii, p. 396-397.
+
+HINDLE, E. 1911 a. The relapsing fever of tropical Africa. A Review.
+   Parasitology, iv, p. 183-203.
+
+---- 1911 b. On the life cycle of _Spirochæta gallinarum_. ibid., iv. p.
+   463-477.
+
+HINDLE, E. and MERRIMAN, G. 1914. The range of flight of _Musca
+   domestica_. Journ. of Hygiene, xiv. p. 23-45.
+
+HINE, J. S. 1903. Tabanidæ of Ohio. Papers Ohio Acad. Sci. No. 5, 55 p.
+
+---- 1906. Habits and life-histories of some flies of the family
+   Tabanidæ. U. S. Dept. Agric. Bur. Ent. tech. bul. 12, p. 19-38.
+
+---- 1907. Second report upon the horse-flies of Louisiana. La. Stat.
+   Exp. Bul. 93, p. 1-59.
+
+HODGE, C. F. 1910. A practical point in the study of the typhoid, or
+   filth-fly. Nature Study Review, vi, p. 195-199.
+
+---- 1913. The distance house-flies, blue-bottles, and stable flies may
+   travel over water. Science, n. s. xxxviii, p. 513.
+
+HONEIJ, J. A. and PARKER, R. R. 1914. Leprosy: flies in relation to the
+   transmission of the disease. Journ. Med. Research, Boston, xxx, p.
+   127-130.
+
+HOOKER, W. A. 1908 a. Life history, habits, and methods of study of the
+   Ixodoidea. Jour. Econ. Ent. i, p. 34-51.
+
+---- 1908 b. A review of the present knowledge of the rôle of ticks in
+   the transmission of disease. ibid., i, p. 65-76.
+
+HOPE, F. W. 1837. On insects and their larvæ occasionally found in the
+   human body. Trans. Ent. Soc., London, ii, p. 256-271.
+
+HOUGH, G. DE N. 1899 a. Synopsis of the Calliphorinæ of the United
+   States. Zoological Bulletin, ii, p. 283-290.
+
+---- 1899 b. Some Muscinæ of North America, Biological Bulletin i, p.
+   19-33.
+
+---- 1899 c. Some North American Genera of Calliphorinæ. Entom. News,
+   x, p. 62-66.
+
+HOVARTH, G. 1912. Revision of the American Cimicidæ. Ann. Mus. Nat.
+   Hungarici, x, p. 257-262.
+
+HOWARD, C. W. 1908. A list of the ticks of South Africa, with
+   descriptions and keys to all the forms known. Ann. Transvaal Mus. 1,
+   p. 73-170.
+
+HOWARD, C. W. and CLARK, P. F. 1912. Experiments on insect transmission
+   of the virus of poliomyelitis. Journ. Exper. Med. xvi, p. 805-859.
+
+HOWARD, L. O. 1899. Spider bites and kissing bugs. Pop. Sci. Mo. lv, p.
+   31-42.
+
+---- 1900. A contribution to the study of the insect fauna of human
+   excrement. Proc. Wash. Acad. Sci. ii, p. 541-604.
+
+---- 1901. Mosquitoes, how they live, how they carry disease, how they
+   are classified, how they may be destroyed. 8vo. New York, Doubleday,
+   Page & Co. (xv + 241 p.)
+
+---- 1909. Economic loss to the people of the United States, through
+   insects that carry disease. U. S. Dept. Agric. Bur. of Ent. Bul. 78,
+   p. 1-40.
+
+HOWARD, L. O., DYAR, H. G. and KNAB, F. 1913-. The mosquitoes of North
+   and Central America and the West Indies. Vol. I. A general
+   consideration of mosquitoes, their habits, and their relations to the
+   human species. 4^o. Carnegie Institution of Washington (vii + 520
+   p.).
+
+HOWARD, L. O. and MARLATT, C. L. 1902. The principal household insects
+   of the United States. U. S. Dept. Agric., Bur. Ent. Bul. 4.
+
+HUEBNER, W. 1907. Ueber das Pfeilgift der Kalahari. Arch. exper. Path.
+   und Pharm., lvii, p. 358-366.
+
+HUNTER, S. J. 1913. Pellagra and the sand-fly. Jour. econ. Ent. vi, p.
+   96-99.
+
+HUNTER, W. D. 1913. American interest in medical entomology. Jour. econ.
+   Ent. vi, p. 27-39.
+
+HUNTER, W. D. and BISHOPP, F. C. 1910. Some of the more important ticks
+   of the United States. U. S. Dept. Agric. Yearbook 1910, p. 219-230,
+   pls. xv-xvi.
+
+---- 1911. The Rocky Mountain spotted fever tick. With special reference
+   to the problem of its control in the Bitter Root Valley in Montana.
+   U. S. Dept. Agric., Bur. Ent. Bul. 105, p. 1-47.
+
+HUTCHISON, R. H. 1914. The migratory habit of housefly larvæ as
+   indicating a favorable remedial measure. An account of progress. U.
+   S. Dept. Agric., Bul. 14, p. 1-11.
+
+JENNINGS, A. H. 1914. Summary of two years' study of insects in relation
+   to pellagra. Journ. of Parasitology, i, p. 10-21.
+
+JENNINGS, A. H. and KING, W. V. 1913. One of the possible factors in the
+   causation of pellagra. Journ. Amer. Med. Assoc., lx, p. 271-274.
+
+JEPSON, F. P. 1909. Notes on colouring flies for purposes of
+   identification. Rep't to the Local Gov't Board on Publ. Health, n. s.
+   16, p. 4-9.
+
+JOHANNSEN, O. A. 1903. Aquatic Nematocerous Diptera. N. Y. State Mus.
+   Bul., 68, p. 328-448, pls. 32-50.
+
+---- 1905. Aquatic Nematocerous Diptera II. (Chironomidæ). ibid. 86, p.
+   76-330, pls. 16-37.
+
+---- 1908. North America Chironomidæ. ibid., 124, p. 264-285.
+
+---- 1911. The typhoid fly and its allies. Maine Agric. Exp. Sta. Bul.,
+   401, p. 1-7.
+
+---- 1911. Simulium and pellagra. Insect Notes for 1910. Maine Agr.
+   Exper. Station. Bul. 187, p. 4.
+
+KELLOGG, V. L. 1915. Spider poison. Jour. of Parasitology, i, p. 107+
+
+KELLY, H. A. 1907. Walter Reed and yellow fever. 8vo. New York, McClure,
+   Phillips & Co. (xix + 310 p.).
+
+KEPHART, CORNELIA F. 1914. The poison glands of the larva of the
+   browntail moth (Euproctis chrysorrhoea Linn.). Journ. Parasit., i,
+   p.
+
+KIEFFER, J. J. 1906. Chironomidæ. Genera Insectorum. Fasc. 42, p. 1-78.
+
+---- 1913. Nouv. étude sur les Chironomides de l'Indien Museum de
+   Calcutta. Records of the Indian Mus., ix, p. 119-197.
+
+KING, A. F. A. 1883. Insects and disease--mosquitoes and malaria. Pop.
+   Sci. Mo. xxiii, p. 644-658.
+
+KIRKLAND, A. H. 1907. Second annual report of the Superintendent for
+   suppressing the gypsy and browntail moths. 8vo. Boston. 170 p.
+
+KLEINE, E. 1909. Postive Infektionsversuche mit _Trypanosoma brucei_
+   durch _Glossina palpalis._ Deutsche med. Wochenschr., xxxv, p.
+   469-470.
+
+   Weitere wissenschaftliche Beobachtungen über die Entwicklung von
+      Trypanosomen in Glossinen. ibid. p. 924-925.
+
+   Weitere Untersuchungen über die Ætiologie der Schlafkrankheit. ibid.,
+      p. 1257-1260.
+
+   Weitere Beobachtungen über Tsetsefliegen und Trypanosomen. ibid., p.
+      1956-1958.
+
+KLING, C. and LEVADITI, C. 1913. Études sur la poliomyélite aiguë
+   épidémique. Ann. Inst. Pasteur, xxvii, p. 718-749, 739-855.
+
+KNAB, F. 1912. Unconsidered factors in disease-transmission by
+   blood-sucking insects. Journ. Econ. Ent., v, p. 196-200.
+
+---- 1913 a. The species of Anopheles that transmit human malaria. Amer.
+   Journ. Trop. Dis. and Preventive Med., i, p. 24-43.
+
+---- 1913 b. Anopheles and malaria. ibid., i, p. 217.
+
+---- 1913 c. The life history of _Dermatobia hominis_. ibid., i, p.
+   464-468.
+
+KNAB, F. See Howard, Dyar, and Knab.
+
+KOBERT, R. 1893. Lehrbuch der Intoxikationen. 4^o. Stuttgart, Enke. (xxii
+   + 816 p.). 2d ed. in 2 vols., 1906.
+
+---- 1901. Beiträge zur Kenntniss der Giftspinnen. 8^o. Stuttgart, Enke.
+   (viii + 191 p.).
+
+KOLBE, H. J. 1894. Der Pfeilgiftkäfer der Kalahari-Wüste, _Diamphidia
+   simplex_. Stett. Ent. Zeitg., iv, p. 79-86.
+
+KRAUSE, M. 1907. Untersuchungen über Pfeilgifte aus unseren
+   africanischen Kolonien. Verhand. deutsche Kolonien kong. 1905. p.
+   264-288.
+
+LALLIER, P. 1897. Étude sur la myase du tube digestif chez l'homme.
+   Thesis, Paris, 8^o. 120 p.
+
+LANGER, J. 1897. Ueber das Gift unserer Honigbiene. Archiv. exper. Path.
+   und Pharm., xxxviii, p. 381-396.
+
+LAVINDER, C. H. 1911. Pellagra: a précis. U. S. Publ. Health Service
+   Bul. 48, 37 p.
+
+LEIDY, J. 1847. History and anatomy of the hemipterous genus
+   _Belostoma_. Journ. Acad. Philad. (2), i, p. 57-67.
+
+LEIPER, R. T. 1907. The etiology and prophylaxis of dracontiasis.
+   British Med. Journ. 1907, p. 129-132.
+
+LEISHMAN, W. B. 1910 a. Observations on the mechanism of infection in
+   tick fever and on the hereditary transmission of _Spirochæta duttoni_
+   in the tick. Trans. Soc. Trop. Med. Hyg., iii, p. 77-95. Abstr. in
+   Bul. Inst. Pasteur, viii, p. 312-313.
+
+---- 1910 b. On the hereditary transmission and mechanism of infection
+   in tick fever and on the hereditary transmission of _Spirochæta
+   duttoni_ in the tick. Lancet., clxxvii, p. 11.
+
+LINNELL, R. McC. 1914. Notes on a case of death following the sting of a
+   scorpion. Lancet, 1914, p. 1608-1609.
+
+LIVINGSTONE, D. 1857. Missionary travels and researches in South Africa.
+
+LUCAS, H. 1843. (note) _Latrodectus malmignatus_ Bul. Soc. Ent., France,
+   1843, p. viii.
+
+LUDLOW, C. S. 1914. Disease bearing mosquitoes of North and Central
+   America, the West Indies and the Philippine Islands. War Dept.,
+   Office of Surgeon General. Bul. No. 4, 1-96.
+
+LUGGER, 1896. Insects injurious in 1896. Agr. Exp. Sta. Bul. 48. p. 33
+   to 270.
+
+MacCALLUM, W. C. 1898. On the hæmatozoan infection of birds. Journ. Exp.
+   Med. iii, p. 117.
+
+MacGREGOR, M. E. 1914. The posterior stigmata of dipterous larvæ as a
+   diagnostic character. Parasitology, vii, p. 176-188.
+
+MacLOSKIE, G. 1888. The poison apparatus of the mosquito. Amer.
+   Naturalist, xxii, p. 884-888.
+
+MALLOCH, J. P. 1913. American black-flies or Buffalo gnats. U. S. Dept.
+   Agric. Bur. Ent. Tech. Bul. 26, p. 1-72.
+
+---- 1914. Notes on North American Diptera. Bul. Illinois State Lab.
+   Nat. Hist., x, p. 213-243.
+
+MANSON, P. 1911. Tropical diseases: a manual of the diseases of warm
+   climates. 8^o. London, Cassell & Co. (xx + 876 p.). 4 ed. (1907).
+   Reprinted.
+
+MARCHOUX, E. and COUVY, L. 1913. Argas et spirochætes (1 mémoire). Les
+   granules de Leishman. Ann. Inst. Pasteur, xxvii, p. 450-480. 2
+   mémoire. Le virus chez l'acarien. ibid. p. 620-643.
+
+MARCHOUX, E. and SELIMBENI, A. 1903. La spirillose des poules. Ann.
+   Inst. Pasteur, xvii, p. 569-580.
+
+MARCHOUX, E. and SIMOND, P. L. 1905. Études sur la fièvre jaune. Ann.
+   Inst. Pasteur, xx, pp. 16-40, 104-148, 161-205.
+
+MARLATT, C. L. 1902. (See Howard, L. O. and Marlatt, C. L.)
+
+---- 1907. The bed-bug (_Cimex lectularius_ L.) U. S. Dept. Agric., Bur.
+   Ent., Circ. No. 47, revised ed., 8 pp.
+
+MARTIN, G. LEBOEUF, and ROUBAUD. 1909. Rapport de la mission d'études de
+   la maladie du sommeil au Congo français. 4^o. Paris, Masson & Cie.
+   (vi + 722 p., 8 pls. and map.).
+
+MAVER, MARIA B. 1911. Transmission of spotted fever by other than
+   Montana and Idaho ticks. Journ. Infec. Dis., viii, p. 322-326.
+
+McCLINTIC, T. B. 1912. Investigations of and tick eradications in Rocky
+   Mountain spotted fever. Publ. Health Repts., Washington, xxvii, p.
+   732-760.
+
+MECKEL, H. 1847. Uber schwarzes Pigment in der Milz und im Blute einer
+   Geisteskranken. Allgem. Zeitschr. f. Psychiatrie, iv, p. 198-226.
+
+MEGNI, P. 1906. Les insectes buveurs de sang. 12mo. Paris, Rudeval. (150
+   p.).
+
+MELNIKOFF, N. 1869. Ueber die Jugendzustände der _Tænia cucumerina_.
+   Arch. f. Naturg., xxxv, p. 62-70.
+
+MENSE, C. 1913. Handbuch der Tropenkrankheiten. 1 Band. 4^o. Leipzig,
+   Barth (xv + 295 p.) Entomological parts by A. Eysell, and by Doerr
+   and Russ.
+
+MINCHIN, E. A. 1912. An introduction to the study of the Protozoa, with
+   special reference to the parasitic forms. 8^o. London. Arnold (xi +
+   517 p.).
+
+MITCHELL, EVELYN G. 1907. Mosquito life. 8vo. New York, Putmans. (xxii +
+   281 p.).
+
+MITZMAIN, M. B. 1910. General observations on the bionomics of the
+   rodent and human flies. U. S. Publ. Health Service. Bul., 38, p.
+   1-34.
+
+---- 1912. The rôle of _Stomoxys calcitrans_ in the transmission of
+   _Trypanosoma evansi_. Philippine Journ. Sci., vii, p. 475-519, 5 pls.
+
+---- 1913 a. The biology of _Tabanus striatus_ Fabricius, the horsefly
+   of the Philippines. ibid., vii, B. p. 197-221.
+
+---- 1913 b. The mechanical transmission of surra. ibid., viii, sec. B.,
+   p. 223-229.
+
+---- 1914 a. Experimental insect transmission of anthrax. U. S. Public
+   Health Repts. xxix, p. 75-77.
+
+---- 1914 b. I. Collected studies on the insect transmission of
+   _Trypanosoma evansi_. II. Summary of experiments in the transmission
+   of anthrax by biting flies. U. S. Pub. Health Service, Hyg. Lab.
+   Bul., 94, p. 1-48.
+
+MIYAKE, H. and SCRIBA, J. 1893. Vorläufige Mitteilung über einen neuen
+   Parasit des Menschen. Berl. klin. Wochenschr., xxx, p. 374.
+
+MOLLERS, B. 1907. Experimentelle Studien über die Uebertragung des
+   Rückfallfiebers durch Zecken. Zeitschr. für Hyg. u.
+   Infektionskrankheiten, lviii, p. 277-286.
+
+MOTE, D. C. 1914. The cheese-skipper (_Piophila casei_). Ohio Naturalist
+   xiv, p. 309-310.
+
+NEIVA, A. 1910. Beiträge zur Biologie der _Conorhinus megistus_ Burm.
+   Memorias de Institute Oswaldo Cruz., ii, p. 206-212.
+
+NEVEU-LEMAIRE, M. 1907. Un nouveau cas de parasitisme accidental d'un
+   myriapode dans le tube digestif de l'homme, C. R. Soc. der Biol.,
+   lxiii p. 305-308.
+
+---- 1908. Précis de parasitologie humaine. 8vo. Paris, Rudeval. (v +
+   712 p.).
+
+NEWSTEAD, R. 1911. The papataci flies (Phlebotomus) of the Maltese
+   Islands. Bul. of Ent. Research, ii, p. 47-78, pls. 1-3.
+
+NICOLL, W. 1911. On the part played by flies in the disposal of the eggs
+   of parasitic worms. Repts. to the Local Gov't. Board on Publ. Health
+   and Med. Subjects, n. s. No. 53, p. 13-30.
+
+NICOLLE, C. 1910, Recherches expérimentales sur la typhus exanthématique
+   entreprises à l'Institut Pasteur de Tunis pendant l'année 1909. Ann.
+   Inst. Pasteur, xxiv, p. 243-275.
+
+---- 1911. Recherches expérimentales sur la typhus exanthématique
+   entreprises à l'Institut Pasteur de Tunis pendant l'année 1910.
+   ibid., xxv, p. 1-55, 97-154.
+
+NICOLLE, C., BLAIZOT, A., and CONSEIL, E. 1912 a. Étiologie de la fièvre
+   récurrente. Son mode de transmission par le pou. C. R. Acad. Sci.,
+   cliv, p. 1636-1638.
+
+---- 1912 b. Conditions de transmission de la fièvre récurrente par le
+   pou. ibid., clv., p. 481-484.
+
+NICOLLE, C. and CATOUILLARD, G. 1905. Sur le venin d'un scorpion commun
+   de Tunisie (_Heterometrus maurus_). C. R. Soc. Biol. lviii: p.
+   100-102.
+
+NOE, G. 1901. Sul ciclo evolutivo della _Filaria bancrofti_ e delta
+   _Filaria immitis_. Ricerche labr. anat. comp. norm. Univ. di Roma.,
+   viii, p. 275-353.
+
+NORMAN, W. W. 1896. The effect of the poison of centipedes. Trans. Texas
+   Acad. Sci., i, p. 118-119.
+
+NUTTALL, G. H. F. 1899. On the rôle of insects, arachnids, and myriapods
+   as carriers in the spread of bacterial and parasitic diseases of man
+   and animals. Johns Hopkins Hosp. Repts., viii, 154 p., 3 pls.
+
+---- 1908 a. On the behavior of Spirochætæ in _Acanthia lectularia_.
+   Parasitology, i, p. 143-151.
+
+---- 1908 b. The transmission of _Trypanosoma lewisi_ by fleas and lice.
+   ibid., i, p. 296-301.
+
+---- 1908 c. The Ixodoidea or ticks, spirochætosis in man and animals,
+   piroplasmosis. Journ. Roy. Inst. Publ. Health, xvi, p. 385-403,
+   449-464, 513-526.
+
+---- 1914. Tick paralysis in man and animals. Parasitology, vii, p.
+   95-104.
+
+NUTTALL, G. H. F. and JEPSON, F. P. 1909. The part played by _Musca
+   domestica_ and allied (non-biting) flies in the spread of infective
+   diseases. A summary of our present knowledge. Rept. to the Local
+   Gov't Board on Publ. Health and Med. Subjects, n. s. 16, p. 13-41.
+
+NUTTALL, G. H. F. and SHIPLEY, E. A. 1901-03. Studies in relation to
+   malaria. The structure and biology of Anopheles. Journ. Hyg., vols.
+   i, ii, and iii.
+
+ORTH, J. 1910. Ueber die Beziehungungen der Haarsackmilbe zu
+   Krebsbildungen in der Mamma. Berliner klin. Wochenschr., xlvii, p.
+   452-453.
+
+OSBORN, HERBERT. 1896. Insects affecting domestic animals. U. S. Dept.
+   Agric., Bur. of Ent. Bul., 5, n. s., 302 p.
+
+---- 1902. Poisonous insects. Article in Reference Handbook. Med. Sci.,
+   v, p. 158-169.
+
+OSLER, W. 1887. An address on the Hæmatozoa of malaria. British Med.
+   Jour. i. p. 556.
+
+OSTEN SACKEN, C. R. 1875-78, Prodrome of a Monograph of North American
+   Tabanidæ. Mem. Boston Soc. Nat. Hist., ii, p. 365-397, 421-479, and
+   555-566.
+
+OUDEMANS, A. C. 1910. Neue Ansichten über die Morphologie des
+   Flohkopfes, sowie über die Ontogenie, Phylogenie und Systematik der
+   Flöhe. Novit. Zool., xvi, p. 133-158.
+
+PATTON, W. S. 1907. Preliminary report on the development of the
+   Leishman-Donovan body in the bed-bug. Sci. Mem., Med. and Sanitary
+   Dept., Gov't of India, 28, p. 1-19.
+
+PATTON, W. S. and CRAGG, F. W. 1913. A textbook of medical entomology.
+   4^o. London, Christian Literature Society for India. (xxxiv + 764 p.)
+
+PAWLOWSKY, E. 1906. Ueber den Steck- und Saug-apparat der Pediculiden.
+   Zeitschr. wiss. Insektenbiol., ii, p. 156-162, 198-204.
+
+PAWLOWSKY, E. 1913. Scorpiotomische Mitteilungen. I. Ein Beitrag zur
+   Morphologie des Giftdrüsen der Skorpione. Zeitschr. wiss. Zool., cv.,
+   p. 157-177. Taf. x-xi.
+
+PEPPER, W., SCHNAUSS, F. W., and SMITH, A. J. 1908. Transient parasitism
+   in men by a species of _Rhizoglyphus_. Univ. of Pa. Med. Bul. xxi, p.
+   274-277.
+
+PETROVSKAIA, MARIA. 1910. Sur les myases produites chez l'homme par les
+   Oestrides (Gastrophilus et Rhinoestrus). Thèse, Fac. de médecine,
+   Paris, 79 p.
+
+PETTIT, A. and KROHN, A. 1905. Sur la structure des glandes salivaires
+   du Notonecte (_Notonecta glauca_). Arch. anat. micr. Paris, vii, p.
+   351-368, pl. 13.
+
+PHISALIX, MME. 1900. Un venin volatil. Sécrétion cutanée du _Iulus
+   terrestris_. C. R. Soc. Biol. Paris, 1900, p. 1033-1036.
+
+---- 1912. Effets physiologiques du venin de la Mygale de Haïti, le
+   _Phormictopus cancerides_ Pocock. Effets physiologiques du venin de
+   la Mygale de Corse (_Cteniza sauvaga_ Rossi); Bul. Mus. Paris, 1912:
+   134-138.
+
+PORTSCHINSKY, I. A. 1908. _Rhinoestrus purpureus_, a parasite of
+   horses which deposits its larvæ in the eyes of man. Mss. transl. by
+   Miss S. L. Weissman, in library of Ent. Dept., Cornell University.
+
+---- 1910. Biology of _Stomoxys calcitrans_ and other coprophagous
+   flies. Monograph in Russian. Mss. summarized transl. by Miss S. L.
+   Weissman, in Library of Ent. Dept., C. U.
+
+---- 1911. _Gastrophilus intestinalis_. Mss. transl. by Miss S. L.
+   Weissman, in library of Ent. Dept., C. U.
+
+---- 1913 a. The sheep gad-fly, _Oestrus ovis_, its life, habits,
+   methods of combating it, and its relation to man. Russian. Mss.
+   summarized trans. by Miss S. L. Weissman, in library of Ent. Dept.,
+   C. U.
+
+---- 1913 b. _Muscina stabulans_. A monograph in Russian. Mss., trans.
+   by J. Millman, in library of Ent. Dept., Cornell Univ.
+
+PROWAZEK, S. 1905. Studien über Säugetiertrypanosomen. Arb. aus dem
+   kais. Gesundheitsamte xxii, p. 351-395.
+
+PUSEY, W. A. 1911. The principles and practice of dermatology. 2 ed,
+   8vo. Appleton & Co. (1079 p.)
+
+RABINOWITSCH, L. and KEMPNER, W. 1899. Beitrag zur Kentniss der
+   Blutparasiten, speciell der Ratten trypanosomen. Zeitschr. f. Hyg.
+   xxx, p. 251-291.
+
+RANSOM, B. H. 1904. An account of the tape worms of the genus
+   _Hymenolepis_ parasitic in man. Bul. No. 18, Hyg. Lab., U. S. Pub.
+   Health and Mar.-Hosp. Serv., Wash., p. 1-138.
+
+---- 1911. The life history of a parasitic nematode, _Hebronema muscæ_.
+   Science n. s. xxxiv, p. 690-692.
+
+---- 1913. The life history of _Habronema muscæ_, (Carter), a parasite
+   of the horse transmitted by the house-fly. U. S. Dept. Agric. Bur.
+   Animal, Ind. Bul. 163, p. 1-36.
+
+REAUMUR, R. A. F. DE. 1738. Mémoires pour servir a l'histoirie des
+   insectes. Histoire des cousins, iv, p. 573-636.
+
+REED, WALTER. 1900. The etiology of yellow fever. Philadelphia Med.
+   Jour. Oct. 27, 1900, vi, p. 790-796.
+
+REED, W. and CARROLL, J. 1901. The prevention of yellow fever. Med.
+   Record, Oct. 26, 1901, p. 441-449.
+
+REUTER, ENZIO. 1910. Acari und Geschwulstätiologie. Centralbl. Bakt.
+   Jena. Abt. 1 lvi.; Originale 339-344.
+
+REUTER, O. M. 1912. Bemerkungen über mein neues Heteropterensystem. Ofv.
+   Finska Vetensk. Soc. Förh., liv. Afd. A. vi, p. 1-62.
+
+RIBAGA, C. 1897. Sopra un organo particolare della Cimici dei letti
+   (_Cimex lectularius_ L.). Rivista di Patologia Vegetale, v, p.
+   343-352.
+
+RICARDO, GERTRUDE. 1900. Notes on the Pangoninæ. Ann. and Mag. Nat.
+   Hist. v, p. 97-121.
+
+---- 1901. Further Notes on the Pangoninæ. ibid. viii, p. 286-315.
+
+---- 1904. Notes on the smaller genera of the Tabanidæ. ibid. xiv, P.
+   349-373.
+
+RICKETTS, H. T. 1906-1910. Contributions to medical sciences by Howard
+   Taylor Ricketts. 1870-1910. Univ. of Chicago Press. 1911.
+
+---- 1909. A microorganism which apparently has a specific relationship
+   to Rocky Mountain spotted fever. A preliminary report. Jour. Amer.
+   Med. Assoc. iii, p. 373-380.
+
+---- Spotted fever reports 1 and 2. In the 4th Bien. Rept. State Board
+   of Health, Montana, 1909, p. 87-191.
+
+RICKETTS, H. T. and WILDER, R. M. 1910. The transmission of the typhus
+   fever of Mexico (tabardillo) by means of the louse, _Pediculus
+   vestimenti_. Journ. Am. Med. Assoc. liv. p. 1304.
+
+RILEY, C. V. and HOWARD, L. O. 1889. A contribution to the literature of
+   fatal spider-bites. Insect life, Washington, i. p. 204-211.
+
+RILEY, W. A. 1906. A case of pseudoparasitism by dipterous larvæ.
+   Canadian Ent. xxxviii, p. 413.
+
+---- 1910 a. Earlier references to the relation of flies to disease.
+   Science n. s. xxxi, p. 263-4.
+
+---- 1910 b. _Dipylidium caninum_ in an American child. Science n. s.
+   xxxi, p. 349-350.
+
+---- 1911. The relation of insects to disease. Cornell Countryman ix, P.
+   51-55.
+
+---- 1912 a. Notes on the relation of insects to disease. 8vo. Ithaca,
+   N. Y. 51 p.
+
+---- 1912 b. Notes on animal parasites and parasitism. 8vo. Ithaca, N.
+   Y. 55 p.
+
+---- 1913. Some sources of laboratory material for work on the relations
+   of insects to disease. Ent. News. xxiv, p. 172-175.
+
+---- 1914. Mr. Nott's theory of insect causation of disease. Jour. of
+   Parasitology. i, p. 37-39.
+
+ROSENAU, M. J. and BRUES, C. T. 1912. Some experimental observations on
+   monkeys, concerning the transmission of poliomyelitis through the
+   agency of _Stomoxys calcitrans_. Monthly Bul. Mass. State Board of
+   Health. Vol. vii, p. 314-317.
+
+ROSS, R. 1904. Researches on Malaria. The Nobel Medical Prize Lecture
+   for 1902, Stockholm, Norstedt & Söner. 89 p. 9 pls. In "Les Prix
+   Nobel en 1902."
+
+---- 1910. The prevention of malaria. 4^o. New York. Dutton & Co. (xx +
+   669 p.).
+
+ROTHSCHILD, N. C. 1905 a. North American Ceratophyllus. Novitates
+   Zoologicæ xii, p. 153-174.
+
+---- 1905 b. Some further notes on _Pulex canis_ and _P. felis_. ibid.
+   xii, p. 192-193.
+
+ROUBAUD, E. 1911. Les Choeromyies. C. R. Acad. Sci. Paris, cliii, p.
+   553.
+
+---- 1913. Recherches sur les Auchméromyies. Bul. Sci. France et Belg.
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+
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+   Referate, p. 788.
+
+SAMBON, L. W. 1908. Report presented at the International Conference on
+   Sleeping Sickness.
+
+---- 1910. Progress report on the investigation of pellagra. Reprinted
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+   Danielsson, 12^o. 125 p.
+
+SANDERSON, E. D. 1910. Controlling the black-fly in the White Mountains.
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+
+SAUL, E. 1910. Untersuchungen über Beziehungen der Acari zur
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+   15-18.
+
+SAUL, E. 1913. Beziehungen des Helminthen und Acari zur
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
+SKELTON, D. S. and PARKHAM, J. G. 1913. Leprosy and the bed-bug. R. A.
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+
+SKINNER, H. 1909. A remedy for the house-fleas. Journ. Econ. Ent. ii, p.
+   192.
+
+SMITH, G. U. 1909. On some cases of relapsing fever in Egypt and the
+   question of carriage by domestic vermin. Résumé in Ann. Inst. Pasteur
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+
+SMITH, J. B. 1904. Report upon the mosquitoes occurring within the
+   State, their habits, life history, etc. N. J. Agric. Exp. Sta. 1904,
+   p. 1-482.
+
+---- 1908. The house mosquito, a city, town, and village problem. N. J.
+   Agric. Exp. Sta. Bul. No. 216, p. 1-21.
+
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+   causation, and prevention of Texas or southern cattle fever. U. S.
+   Dept. Agric., Bur. Animal Ind. Bul. 1, p. 1-301. 10 pls.
+
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+
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+
+STILES, C. W. 1905. A zoological investigation into the cause,
+   transmission, and source of Rocky Mountain fever. U. S. Public Health
+   and Marine Hosp. Serv. Hyg. Labr. Bul. 14, 121 p.
+
+---- 1907. Diseases caused by animal parasites. Osler's Modern Medicine,
+   i, p. 525-637.
+
+---- 1910 a. The sanitary privy: its purpose and construction. Public
+   Health Bul. No. 37. U. S. Pub. Health and Marine Hosp. Service, p.
+   1-24.
+
+---- 1910 b. The taxonomic value of the microscopic structure of the
+   stigmal plates in the tick genus _Dermacentor_. Bul. No. 62; Hyg.
+   Lab., U. S. Pub. Health and Mar. Hosp. Serc., Washington, p. 1-72. 43
+   pls.
+
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+   excreta. Public Health Repts. Washington. xxv, p. 1825-1830.
+
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+   Spores. The contamination of food with human excreta. Public Health
+   Repts. Washington, xxviii, p. 2530-2534.
+
+STILES, C. W. and LUMSDEN, L. L. 1911. The sanitary privy. U. S. Dept.
+   Agric., Farmers Bul. 463, 32 p.
+
+STRICKLAND, C. 1914. The biology of _Ceratophyllus fasciatus_ Bosc., the
+   common rat-flea of Great Britain. Jour. Hygiene, xiv, p. 139-142.
+
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+   Intern. Plague Conf. held at Mukden, Apr. 1911, p. 83-87.
+
+STRONG, R. P., TYZZER, E. E., and BRUES, C. T. 1913. Verruga peruviana,
+   Oroya fever and uta. Journ. Amer. Med. Assoc. lxi, p. 1713-1716.
+
+STRYKE, ANNA C. 1912. The life-cycle of the malarial parasite. Entom.
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+
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+   Acad. Sci., Paris, clvi, p. 1406-1408.
+
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+   325 p.).
+
+TAUTE, M. 1911. Experimentelle Studien über die Beziehungen der
+   _Glossina morsitans_ zur Schlafkrankheit. Zeitschr. f. Hyg. lxix, p.
+   553-558.
+
+TEMPLE, I. U. 1912. Acute ascending paralysis, or tick paralysis.
+   Medical Sentinel, Portland, Oregon. Sept. 1912. (Reprint unpaged.)
+
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+   volumes. London.
+
+THEBAULT, V. 1901. Hémorrhagie intestinale et affection typhiode causée
+   par des larves de Diptère. Arch. Parasit. iv, p. 353-361
+
+THOMPSON, D. 1913. Preliminary note on bed-bugs and leprosy. British
+   Med. Journ. 1913, p. 847.
+
+TIRABOSCHI, C. 1904. Les rats, les souris et leurs parasites cutanés
+   dans leurs rapports avec la propagation de la peste bubonique. Arch.
+   Parasit. viii, p. 161-349.
+
+TOPSENT, E. 1901. Sur un cas de myase hypodermique chez l'homme. Arch.
+   Parasit., iv. p. 607-614.
+
+TORREY, J. C. 1912. Numbers and types of bacteria carried by city flies.
+   Journ. of Inf. Dis., x, p. 166-177.
+
+TOWNSEND, C. H. T. 1908. The taxonomy of the Muscoidean flies.
+   Smithsonian Misc. Col., p. 1-138.
+
+---- 1911. Review of work by Pantel and Portchinski on reproductive and
+   early stage characters of Muscoid flies. Proc. Ent. Soc., Washington,
+   xiii, p. 151-170.
+
+---- 1912. Muscoid names. ibid., xiv, p. 45.
+
+---- 1913 a. Preliminary characterization of the vector of verruga,
+   _Phlebotomus verrucarum_ sp. nov. Insecutor Inscitiæ Menstruus,
+   Washington, i, p. 107-109.
+
+---- 1913 b. The transmission of verruga by _Phlebotomus_. Journ. Amer.
+   Med. Assoc., lxi, p. 1717.
+
+---- 1914 a. The relations between lizards and _Phlebotomus verrucarum_
+   as indicating the reservoir of verruga. Science n. s., xl, p.
+   212-214.
+
+---- 1914 b. Progress of verruga work with _Phlebotomus verrucarum_ T.
+   Journ. Econ. Ent., vii. p. 357-367.
+
+TROUESSART, E. 1902. Endoparasitisme accidental chez l'homme d'une
+   espèce de Sarcoptidæ détriticole, (_Histiogaster spermaticus_). Arch.
+   Parasit., v, P. 449-459.
+
+TSUNODA, T. 1910. Eine Milbenart von _Glyciphagus_ als Endoparasit. D.
+   med. Wochenschr., xxxvi, p. 1327-1328.
+
+TYZZER, E. E. 1907. The pathology of the brown-tail moth dermatitis. In
+   2d Rept. of the Supt. for Suppressing the Gypsy and Brown-tail Moths,
+   Boston, 1907, p. 154-168.
+
+VAUGHAN,
+
+VERDUN, P. and BRUYANT, L. 1912. Un nouveau cas de pseudo-parasitisme
+   d'un myriapode, (_Chætachlyne vesuviana_) chez l'homme. C. R. Soc.
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+
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+   plague. Transl. from Russian in Jour. Hyg., viii, p. 162-208.
+
+VILLENEUVE, J. 1914. Quelques réflexions au sujet de la tribu des
+   Calliphorinæ Bul. Soc. Ent., France, No. 8, p. 256-258.
+
+WARD, H. B. 1905. The relation of animals to disease. Science n. s.
+   xxii, P. 193-203.
+
+WATSON, J. J. 1910. Symptomology of pellagra and report of cases. Trans.
+   Nat. Conference on Pellagra, Columbia, S. C., Nov. 3 and 4, 1909, p.
+   207-218.
+
+WEED, C. M. 1904. An experiment with black-flies. U. S. Dept. Agric.,
+   Bur. Ent. Bul. n. s., 46, p. 108-109.
+
+WELLMAN, F. C. 1906. Human trypanosomiasis and spirochætosis in
+   Portuguese Southwest Africa, with suggestions for preventing their
+   spread in the Colony. Journ. Hyg., vi, p. 237-345.
+
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+
+WHITFIELD, A. 1912. A method of rapidly exterminating pediculi capitis.
+   Lancet 1912 (2), p. 1648. See notes.
+
+WILLISTON, S. W. 1908. Manual of the North American Diptera, New Haven,
+   p. 1-405.
+
+WILSON, G. B. and CHOWNING, W. M. 1903. Studies in _Piroplasmosis
+   hominis_. Journ. Inf. Dis., iv, p. 31-57.
+
+WILSON, W. H. 1904. On the venom of scorpions. Rec. Egyptian Gov't
+   School of Medicine, Cairo, ii, p. 7-44.
+
+
+
+
+INDEX
+
+
+Abscess, 178
+
+Acanthia, 87
+
+Acariasis, 58
+
+Acarina, 23, 58, 131, 259
+
+Acarus dysenteriæ, 132
+
+Accidental parasites, 131, 132, 134
+
+Aedes, 194, 293
+
+Aedes calopus, 182, 201, 205, 206, 208
+
+Aedes cantator, 101
+
+Aedes sollicitans, 101
+
+Aedes tæniorhynchus, 101
+
+Aerobic bacteria, 152
+
+Æstivo-autumnal, 186
+
+African Relapsing Fever, 230
+
+Akis spinosa, 177
+
+Alternation of Generations, 175
+
+Amblyomma, 264
+
+Amblyomma americanum, 67
+
+Amblyomma cajennense, 67
+
+American dog tick, 228
+
+Amoeboid organism, 189
+
+Anisolabis annulipes, 177
+
+Anterior poliomyelitis, 241
+
+Anopheles, 194, 291
+
+Anopheles crucians, 199
+
+Anopheles maculipennis, 182
+
+Anopheles punctipennis, 198
+
+Anopheles quadrimaculatus, 197
+
+Anopheline, 192
+
+Anthocoris, 279
+
+Anthomyiidæ, 300
+
+Anthomyia, 138
+
+Anthrax, 165
+
+Antipruritic treatment, 72
+
+Ants, 42
+
+Aphiochæta, 295
+
+Apis mellifica, 36
+
+Arachnida, 258
+
+Araneida, 6
+
+Argas, 64
+
+Argas persicus, 63, 235, 237
+
+Argasidæ, 62
+
+Argopsylla, 317
+
+Argus, 259
+
+Arilus, 284
+
+Arthropods, poisonous, 6
+
+Asopia farinalis, 177
+
+Assassin-bugs, 31, 219
+
+Auchmeromyia, 117
+
+Automeris io, 47
+
+Avicularoidea, 12
+
+
+Babesia, 226
+
+Babesia bovis, 223
+
+Babesia ovis, 225
+
+Babesiosis, 221-222
+
+Bacilli, 170
+
+Bacillus icteroides, 202, 205
+
+Bacillus pestis, 166
+
+Bacillus typhosus, 153
+
+Back swimmers, 30
+
+Bdellolarynx, 304
+
+Beauperthuy, Louis Daniel, 2
+
+Bed-bug, 86, 88, 90, 173, 219-220
+
+Bed-bug, cone-nosed, 92
+
+Blister beetles, 54
+
+Belostoma, 28, 277
+
+Belostoma americana, 31
+
+Belostomatidæ, 30
+
+Bengalia, 314
+
+Bird-spiders, 10
+
+Black death, 1, 166
+
+Black flies, 33, 104, 247
+
+Black heads, 80
+
+Blaps mortisaga, 134
+
+Blepharoceridæ, 286
+
+Boophilus, 264
+
+Boophilus annulatus, 67, 223-225
+
+Bot-flies, 112
+
+Blue bottle flies, 140
+
+Brill's disease, 238
+
+Brown-tailed moth, 48
+
+Bruck, 34
+
+Buthus quinquestriatus, 21
+
+
+Cabbage butterfly, 56
+
+Calliphora, 136, 140, 312
+
+Calliphora erythrocephala, 141
+
+Calobata, 296
+
+Camponotinæ, 43
+
+Cancer, 254
+
+Cantharidin, 54
+
+Cantharidin poison, 55
+
+Canthariasis, 134
+
+Capsidæ, 280
+
+Carriers, simple, 4, 144
+
+Carriers of disease, 144
+
+Carrion's fever, 253
+
+Caterpillar rash, 45
+
+Cat flea, 172
+
+Cattle ticks, 222
+
+Causative organism, 170
+
+Cellia, 291
+
+Centipedes, 25, 257
+
+Ceratophyllus, 120, 316
+
+Ceratophyllus acutus, 123
+
+Ceratophyllus fasciatus, 122, 172, 213
+
+Ceratopogon, 108
+
+Cheese-fly, 137
+
+Cheyletus eruditus, 271
+
+Chigger, 60, 70
+
+Chigoes, 126
+
+Chilopoda, 25, 257
+
+Chiracanthium nutrix, 18
+
+Chironomidæ, 107
+
+Chorioptes, 270
+
+Chrysomelid, 55
+
+Chrysomyia, 136, 308
+
+Chrysomyia macellaria, 117, 140
+
+Chrysops, 294
+
+Chylous dropsy, 179
+
+Chyluria, 178
+
+Cicadidæ, 55
+
+Cimex L., 278
+
+Cimex boueti, 92
+
+Cimex columbarius, 92
+
+Cimex hemipterus, 91, 220
+
+Cimex hirundinis, 92
+
+Cimex inodorus, 92
+
+Cimex lectularius, 87, 219
+
+Citheronia regalis, 44
+
+Clinocoris, 87
+
+Coleoptera, 134, 274
+
+Comedons, 80
+
+Complete metamorphosis, 80
+
+Compressor muscle, 20
+
+Compsomyia, 117
+
+Cone-nosed bed-bug, 92
+
+Conjunctivitis, nodular, 52
+
+Conorhinus, 282
+
+Conorhinus megistus, 93, 219-220
+
+Conorhinus rubrofasciatus, 220
+
+Conorhinus sanguisugus, 32, 92
+
+Copra itch, 72
+
+Cordylobia, 118
+
+Coriscus, 280
+
+Coriscus subcoleoptratus, 32
+
+Creeping myasis, 112
+
+Crustacea, 257
+
+Cryptocystis, 176
+
+Cryptotoxic, 54-55
+
+Cteniza sauvagei, 13
+
+Ctenocephalus, 120, 172, 213, 317
+
+Culex, 194, 201, 293
+
+Culex pipiens, 35, 98
+
+Culex quinquefasciatus, 180
+
+Culex sollicitans, 200
+
+Culex territans, 101
+
+Culicidæ, 33, 97
+
+Culicin, 34
+
+Culicoides, 109, 288
+
+Cyclops, 183, 257
+
+Cynomyia, 136, 311
+
+
+Dance, St. Vitus, 8
+
+Dancing mania, 8
+
+Deer-flies, 110
+
+Definitive host, 192
+
+Demodecidæ, 78
+
+Demodex, 259
+
+Demodex folliculorum, 78
+
+Dermacentor, 262
+
+Dermacentor andersoni, 67, 228
+
+Dermacentor occidentalis, 227
+
+Dermacentor variabilis, 67
+
+Dermacentor venustus, 24, 228
+
+Dermanyssidæ, 68
+
+Dermanyssus, 266
+
+Dermanyssus gallinæ, 68
+
+Dermatitis, 72, 77, 85
+
+Dermatobia, 115, 298
+
+Dermatobia cyaniventris, 163
+
+Dermatophilus, 317
+
+Dermatophilus penetrans, 60, 126
+
+Diamphidia simplex, 55
+
+Dimorphism, 65
+
+Direct inoculators, 4
+
+Diplopoda, 25, 257
+
+Diptera, 33, 94, 274
+
+Dipterous Larvæ, 135
+
+Dipylidium, 175, 221
+
+Dipylidium caninum, 4, 175-176
+
+Dog flea, 172
+
+Dracunculus, 257
+
+Dracunculus medinensis, 182
+
+Drosophila, 296
+
+Dum-dum fever, 220
+
+Dysentery, 154
+
+
+Ear-flies, 110
+
+Earwig, 177
+
+Echidnophaga, 317
+
+Echinorhynchus, 185
+
+Elephantiasis, 178-179
+
+Empoasca mali, 33
+
+Empretia, 46
+
+English Plague Commission, 171
+
+Epeira diadema, 18
+
+Epizootic, 170
+
+Eristalis, 137, 295
+
+Essential hosts, 4, 165
+
+Eumusca, 307
+
+European Relapsing Fever, 233
+
+Euproctis chrysorrhoea, 48
+
+Eusimulium, 286
+
+
+Facultative parasites, 131
+
+Fannia, 136, 138, 145, 300
+
+Federal Health Service, 169
+
+Fever, lenticular, 237
+  African Relapsing, 230, 234
+  Carrion's, 253
+  dum-dum, 154
+  European Relapsing, 233
+  pappatici, 96
+  red water, 220
+  Rocky Mt. Spotted, 226
+  three day, 96
+  Typhus, 237
+
+Filaria, 178, 221
+  immitis, 182
+
+Filariasis, 178
+
+Flannel-moth larvæ, 44
+
+Fleas, 119, 166, 213
+  cat, 172
+  dog, 172
+  human, 172, 176
+  rodent, 123, 172
+  rat, 171
+
+Flesope, 125
+
+Formaldehyde, 91
+
+Fomites, 199, 204
+
+Fulgoridæ, 28
+
+Fumigation, 320
+
+
+Gamasid, 68
+
+Gangrene, 129
+
+Gastrophilus, 113, 297
+
+Giant crab spiders, 13
+
+Giant water bugs, 30
+
+Gigantorhynchus, 185
+
+Glossina, 117, 297, 303
+
+Glossina morsitans, 214, 217
+  palpalis, 215, 217, 218
+
+Glyciphagus, 267
+
+Grain moth, 69
+
+Grocer's itch, 72
+
+Guinea-worm, 182
+
+
+Habronema muscæ, 156, 183
+
+Hæmatobia, 166, 304
+  irritans, 146
+
+Hæmatobosca, 304
+
+Hæmatomyidium, 288
+
+Hæmatopinus spinulosus, 213
+
+Hæmatopota, 294
+
+Hæmatosiphon, 279
+
+Hæmoglobinuria, 222
+
+Hæmozoin, 189
+
+Harpactor, 284
+
+Harvest mites, 60
+  effect of, 59
+
+Head-louse, 173
+
+Helminthiasis, 138
+
+Helophilus, 295
+
+Hemiptera, 27, 86, 273-275
+
+Heteropodidæ, 13
+
+Heuchis sanguinea, 55
+
+Hexapod larvæ, 58
+
+Hexapoda, 27, 80, 258
+
+Hippelates, 297
+
+Hippobosca, 285
+
+Histiogaster, 269
+  spermaticus, 132
+
+Homalomyia, 136, 138, 300
+
+Honey bee, 36
+  poison of, 37
+
+Hornets, 43
+
+Horn-fly, 137, 304, 308
+
+Horse-fly, 110, 165
+
+House-fly, 137-139, 144, 183
+  control of, 156, 160
+
+Human flea, 124
+
+Host, definitive, 175
+  intermediate, 175
+  primary, 175
+
+Hyalomma, 264
+  ægypticum, 224-225
+
+Hydrocyanic Acid Gas, 318
+
+Hydrotæa, 300
+
+Hymenolepis diminuta, 176
+
+Hymenoptera, 36, 275
+
+Hypoderma, 113, 298
+  diana, 113
+  lineata, 113
+
+Hypopharynx, 80
+
+
+Immunity from stings, 39
+
+Incomplete metamorphosis, 80
+
+Infantile paralysis, 162, 241
+  splenic, 220
+  Direct inoculation, 164
+
+Insects, 258
+  blood-sucking, 170
+
+Intermediate host, 192, 203
+
+Intestinal infestation, 112, 133
+  myasis, 137
+
+Isosoma, 69
+
+Itch, 73-74
+  mite, 73
+  Norwegian, 77
+
+Ixodes, 260
+  ricinus, 66, 225
+  scapularis, 66
+
+Ixodidæ, 64-65
+
+Ixodoidea, 62
+
+
+Janthinosoma lutzi, 116
+
+Jigger, 60
+
+Johannseniella, 110, 288
+
+Journal of Tropical Medicine and Hygiene, 36
+
+Julus terrestris, 25
+
+June bug, 185
+
+
+Kala-azar, 220
+
+Karakurte, 14
+
+Katipo, 14
+
+King, A. F. A., 3
+
+Kircher, Athanasius, 1, 8
+
+Kissing-bug, 31
+
+
+Labium, 29, 80
+
+Labrum, 28, 80
+
+Lachnosterna, 185
+
+Lælaps, 266
+
+Lagoa crispata, 45
+
+Lamblia intestinalis, 154
+
+Langer, Josef, 37
+
+Larder beetles, 135
+
+Latrodectus, 12, 14, 17
+  mactans, 15
+
+Leishmanioses, 220
+
+Lenticular fever, 237
+
+Lepidoptera, 274
+
+Lepidopterous larvæ, 134
+
+Leprosy, 252
+
+Leptidæ, 112
+
+Leptis, 295
+
+Leptus, 60, 273
+
+Lice, 80
+
+Linguatulina, 258
+
+Liponyssus, 265
+
+Loemopsylla, 172, 317
+
+Lone star tick, 228
+
+Louse, body, 84
+  crab, 85
+  dog, 176
+  head, 82
+  pubic, 85
+
+Lucilia, 136, 312
+
+Lycosa tarantula, 10
+
+Lycosidæ, 10
+
+Lyctocoris, 279
+
+Lygus pratensis, 33
+
+Lymphangitis, 67
+
+Lymph scrotum, 178
+
+Lyperosia, 304
+
+Lyperosiops, 305
+
+
+Macloskie, 34
+
+Maggots, rat-tail, 137
+
+Magnes sive de Arte Magnetica, 8
+
+Malaria, 186
+
+Malmigniatte, 14
+
+Mandibles, 28, 80
+
+Mange, 73-75
+
+Margaropus, 237, 264
+  annulatus, 223
+
+Masked bed-bug hunter, 32
+
+Mastigoproctus giganteus, 19, 80
+
+Maxillæ, 28
+
+Meal infesting species, 135
+
+Melanin granules, 189
+
+Melanolestes, 280
+  picipes, 32
+
+Mena-vodi, 14
+
+Mercurialis, 1
+
+Merozoites, 190
+
+Metamorphosis, 80
+
+Miana bug, 63
+
+Microgametoblast, 192
+
+Midges, 107
+
+Migratory ookinete, 192
+
+Millipedes, 25, 257
+
+Mites, 23, 58
+
+Monieziella, 269
+
+Mosquitoes, 33, 97, 178, 196, 250
+  treatment for bites of, 34, 36, 102
+
+Musca, 137, 307
+  domestica, 139, 145, 146, 157, 162
+
+Muscidæ, 117
+
+Muscina, 137, 146, 307
+  stabulans, 140
+
+Mutualism, 57
+
+Myasis, 112, 135
+  intestinal, 135-140
+  nasal, 141
+
+Mycterotypus, 287
+
+Myiospila, 146, 307
+
+Myriapoda, 225, 132, 257
+
+
+Nagana, 165, 214
+
+Nasal infestation, 114, 133
+
+Necrobia, 135
+
+Nematode parasite, 182
+
+Nepa, 28
+
+Nephrophages sanguinarius, 132
+
+Nettling insects, 43
+  larvæ, poison of, 53
+
+Neurasthenia, 89
+
+Nits, 86
+
+North African Relapsing Fever, 234
+
+Norwegian itch, 77
+
+No-see-ums, 109
+
+Notoedres, 269
+  cati, 78
+
+Notonecta, 28, 277
+
+Notonectidæ, 30
+
+Nott, Dr. Josiah, 2
+
+Nuttall, 34
+
+
+Occipital headaches, 138
+
+Oecacta, 288
+
+Oeciacus, 279
+
+Oesophageal diverticula, 35
+
+Oestridæ, 112, 136
+
+Oestris ovis, 113
+
+Oestrus, 298
+  oocyst, 192
+  ookinete, 192
+
+Opsicoetes personatus, 32
+
+Opthalmia, 155
+  nodosa, 52
+
+Oriental sore, 221
+
+Ornithodoros, 65, 260
+  moubata, 220, 230
+
+Orthotylus flavosparsus, 33
+
+Ornithomyia, 286
+
+Oroya, 253
+
+Oscinus, 297
+
+Otiobius, 259
+  megnini, 65
+
+Otodectes, 271
+
+
+Pangonia, 294
+
+Pappatici fever, 96
+
+Parasimulium, 286
+
+Parasite, 3, 57, 131, 134, 182
+  accidental, 3, 131, 134
+  facultative, 3, 57, 131
+  nematode, 182
+  stationary, 57
+  temporary, 57
+  true, 3
+
+Parasitism, accidental, 134
+
+Pathogenic bacteria, 152
+  organisms, 144, 164
+
+Pawlowsky, 81
+
+Pediculoides, 267
+  ventricosus, 69, 72
+
+Pediculosis, 81
+
+Pediculus, 275
+  corporis, 84, 233, 238
+  humanus, 82, 173
+
+Pellagra, 162, 246
+
+Pernicious fever, 186
+
+Pest, 166
+
+Phidippus audax, 19
+
+Philæmatomyia, 306
+
+Phisalix, 13, 43
+
+Phlebotomus, 289
+  papatasii, 94
+  verrucarum, 254
+  vexator, 95
+
+Phora, 295
+
+Phormia, 136
+
+Phormictopus carcerides, 13
+
+Phthirus pubis, 85, 275
+
+Phortica, 296
+
+Pieris brassicæ, 56
+
+Piophila, 297
+
+Piophila casei, 136, 137
+
+Piroplasmosis, 222
+
+Plague, 166
+  bubonic, 166, 169, 170
+  pneumonic, 167
+
+Plasmodium, 186
+
+Platymetopius acutus, 33
+
+Plica palonica, 83
+
+Pneumonic, 166
+  plague, 167, 173
+
+Poisoning by nettling larvæ, 53
+
+Poison of spiders, 7
+
+Pollenia, 308
+  rudis, 146, 147
+
+Primary gland, 28
+
+Prionurus citrinus, 20
+
+Prosimulium, 286
+
+Protocalliphora, 136, 312
+
+Protozoan blood parasite, 165
+
+Pseudo-tubercular, 52
+
+Psorophora, 293
+
+Psoroptes, 270
+
+Psychodidæ, 94
+
+Pulex, 120, 124, 126, 172, 317
+  cheopis, 172
+  irritans, 124
+  penetrans, 126
+  serraticeps, 120
+
+Pulvillus, 150
+
+Punkies, 109
+
+Pycnosoma, 308
+
+
+Rasahus, 280
+  thoracicus, 32
+
+Rat fleas, 120, 124, 171
+
+Rat louse, 213
+
+Red bugs, 70-72
+
+Reduviidæ, 31
+
+Reduviolus, 280
+
+Reduvius, 282
+  personatus, 32
+
+Redwater fever, 222
+
+Relapsing fever, 230, 233
+
+Rhinoestrus nasalis, 115
+
+Rhipicentor, 264
+
+Rhipicephalus, 264
+
+Rhizoglyphus, 269
+
+Rhodnius, 281
+
+Rocky Mountain Spotted Fever, 226
+  spotted fever tick, 67
+
+Russian gad-fly, 115
+
+
+St. Vitus's or St. John's dance, 8
+
+Salivary syringe, 28
+
+Sand-flies, 109, 250
+
+Sanguinetti, 11
+
+Sarcophaga, 136, 142, 143
+
+Sarcophila, 302
+
+Sarcopsylla, 317
+  penetrans, 126
+
+Sarcoptes, 270
+  minor, 78
+  scabiei, 73
+
+Sarcoptidæ, 72
+
+Scabies, 72, 73, 74, 75
+
+Scaurus striatus, 177
+
+Schaudinn, 34
+
+Schizont, 189, 190
+
+Scholeciasis, 134
+
+Scolopendra morsitans, 26
+
+Scorpions, 20
+  poison of, 21
+
+Screw worm fly, 140
+
+Sepsidæ, 296
+
+Sepsis, 136, 297
+
+Shipley, 34
+
+Sibine, 46
+
+Silvius, 294
+
+Simple carriers, 4, 144
+
+Simuliidæ, 33, 104
+
+Simulium, 247, 249, 286, 321
+  pictipes, 104
+
+Siphonaptera, 119, 274, 316
+
+Siphunculata, 80, 275
+
+Sitotroga cerealella, 69
+
+Skippers, 137
+
+Sleeping sickness, 166, 215
+
+Snipe-flies, 112
+
+Solpugida, 22
+
+Spanish fly, 54
+
+Spermatozoa, 192
+
+Spinose ear-tick, 65
+
+Spirochæta, 35
+  berberi, 234
+  duttoni, 234
+
+Spirochætosis, 235
+
+Sporozoite, 189
+
+Spotted fever, 67, 226
+
+Squirrel flea, 123
+
+Stable-fly, 137, 160, 163, 165
+
+Stegomyia, 182, 293
+  calopus, 206
+  fasciata, 206
+
+Stomoxys, 137, 305
+  calcitrans, 117, 146, 160, 161, 165, 242
+
+Straw-worm, 69
+
+Stygeromyia, 305
+
+Sucking stomach, 35
+
+Sulphur ointment, 77
+
+Surra, 165
+
+Symbiosis, 57
+
+Symphoromyia, 112, 295
+
+
+Tabanidæ, 110
+
+Tabanus, 110, 166, 294
+  striatus, 165
+
+Taenia, 175
+
+Tapeworm, 4, 176
+
+Tarantella, 8
+
+Tarantism, 8
+
+Tarantula, 10
+
+Tarsonemidæ, 69
+
+Tarsonemus, 267
+
+Tenebrionid beetles, 127
+
+Tersesthes, 110, 288
+
+Tetanus, 129
+
+Tetranychus, 273
+
+Texas fever, 220-223
+
+Three-day fever, 96
+
+Tick, 23, 226
+  bites, Treatment of, 68
+  fever, 230
+  paralysis, 67
+
+Treatment,
+  Bee stings, 36, 41
+  Bites of,
+    Bed-bugs, 90, 93
+    Blackflies, 107
+    Buffalo flies, 107
+    Bugs, 31, 33
+    Centipedes, 26, 27
+    Chiggers, 127
+    Chigoes, 127
+    Fleas, 127
+    Harvest mites, 61
+    Jiggers, 129
+    Lice, 83, 85
+    Mosquitoes, 34, 36, 102
+    Phlebotomus flies, 97
+    Sand flies, 96, 107, 109
+    Scorpions, 22, 23
+    Spiders, 19
+    Ticks, 61, 68, 72
+    Ticks, ear, 65
+  Blister beetle poison, 55
+  Brown-tail moth rash, 45
+  Cantharidin poison, 55
+  Caterpillar rash, 45
+  Ear ticks, 65
+  House fly control, 156, 160
+  Itch, 77
+  Itch, grocer's, 72
+  Lice, 85
+  Nasal myasis, 143
+  Rocky Mt. spotted fever, 228, 229
+  Rash, caterpillar, 45
+  Scabies, 77
+  Sleeping sickness control, 218
+  Spotted fever, 228, 229
+  Stings, bee, 36, 41
+  Typhus fever, prophylaxis, 239
+
+Trichodectes canis, 176
+
+Trichoma, 82
+
+Trineura, 295
+
+Trochosa singoriensis, 11
+
+Trombidium, 60, 273
+
+True insects, 80
+
+Trypanosoma, 35
+
+Trypanosoma, brucei, 165
+
+Trypanosoma cruzi, 219
+
+Trypanosoma lewisi, 213
+
+Trypanosomiases, 212
+
+Trypanosomiasis, 165, 219
+
+Tsetse flies, 117, 166, 214, 219
+
+Tsetse flies disease, 165
+
+Tuberculosis, 155
+
+Tumbu-fly, 118
+
+Tydeus, 271
+
+Typhoid, 155
+
+Typhoid fever, 154
+
+Typhus, 237
+
+Typhus fever, 237
+
+Tyroglyphus, 72, 131, 268
+
+Dr. Tyzzer, 49
+
+
+Uranotænia, 292
+
+
+Vancoho, 14
+
+Varicose groin glands, 178
+
+Verruga peruviana, 253
+
+Vescicating insects, 54
+
+
+Wanzenspritze, 29
+
+Warble-flies, 112
+
+Wasps, 43
+
+Whip-scorpions, 19
+
+Wohlfahrtia, 143, 302
+
+Wolf-spiders, 10
+
+Wyeomyia smithii, 101, 293
+
+
+Xenopsylla, 172, 317
+
+Xenopsylla cheopis, 171, 124
+
+Xestopsylla, 317
+
+
+Yaws, 2
+
+Yellow fever, 196, 203, 205
+
+
+
+
+TRANSCRIBER'S NOTES
+
+The following discrepancies in the text are as in the original:
+
+  The inconsistent hyphenation of the following:
+    assassin-bugs/assassin bugs;
+    bedbug/bed-bug (and bedbugs);
+    beekeeper/bee-keeper (and beekeepers);
+    blackflies/black-flies;
+    blow-flies/blow flies;
+    bluebottles/blue-bottles;
+    bot-flies/bot flies;
+    bristlelike/bristle-like;
+    browntail/brown-tail;
+    coextensive/co-extensive;
+    deer-flies/deer flies;
+    dorsocentral/dorso-central;
+    ectoparasites/ecto-parasites;
+    endoparasites/endo-parasites;
+    flesh-fly/flesh fly (and flesh flies);
+    hotbed/hot-bed;
+    housefly/house-fly (and houseflies);
+    horsefly/horse-fly (and horse flies);
+    horse-manure/horse manure;
+    midsummer/mid-summer;
+    preeminently/pre-eminently;
+    sandfly/sand-fly (and sandflies);
+    screw-worm fly/screw worm fly;
+    stable-fly/stable fly;
+    subequal/sub-equal;
+    subfamily/sub-family;
+    subtropical/sub-tropical;
+    tapeworm/tape-worm (and tapeworms);
+    today/to-day;
+    tsetse-flies/tsetse flies;
+    widespread/wide-spread;
+    wormlike/worm-like.
+
+  Inconsistent use of diaeresis in Aëdes/Aedes
+
+  Inconsistent spelling of the following:
+    defence/defense;
+    disc/disk;
+    hemolysis/hæmolysis;
+    hemolytic/hæmolytic;
+    hexapod/hexopod;
+    Levaditi/Lavaditi;
+    metalescent/metallescent;
+    Mitzmain/Mitzman;
+    Neveau-Lemaire/Neveau-Lamaire;
+    offence/offense;
+    Phthirus/Phthirius
+    Portschinsky/Portchinsky/Portchinski;
+    travelled/traveled;
+    ventra-/ventro-;
+    Villot/Villet;
+    Wohlfartia/Wohlfahrtia;
+
+  Inconsistent use of ligatures in Taenia/Tænia
+
+toxine, insiduous, efficaceous, cyanid are spelt as in the original
+
+In the first paragraph of chapter XII, "the student might not be lead"
+is as in the original. Lead perhaps should be led
+
+In the bibliography, the entry for Vaughan without a text specified is
+as in the original
+
+
+
+
+
+End of the Project Gutenberg EBook of Handbook of Medical Entomology, by 
+William Albert Riley and Oskar Augustus Johanssen
+
+*** END OF THIS PROJECT GUTENBERG EBOOK HANDBOOK OF MEDICAL ENTOMOLOGY ***
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+<pre>
+
+The Project Gutenberg EBook of Handbook of Medical Entomology, by 
+William Albert Riley and Oskar Augustus Johanssen
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Handbook of Medical Entomology
+
+Author: William Albert Riley
+        Oskar Augustus Johanssen
+
+Release Date: November 11, 2010 [EBook #34279]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK HANDBOOK OF MEDICAL ENTOMOLOGY ***
+
+
+
+
+Produced by Bryan Ness, Iris Schimandle, Brownfox and the
+Online Distributed Proofreading Team at http://www.pgdp.net
+(This file was produced from images generously made
+available by The Internet Archive/American Libraries.)
+
+
+
+
+
+
+</pre>
+
+
+
+<div class="bbox" style="padding:1em;">
+<h3>TRANSCRIBERS' NOTES</h3>
+<p>Barring some obvious typos, the text has been left
+as printed. Discrepancies identified are listed at the end of the text.
+Most images are linked to a larger image of the same picture.</p>
+</div>
+
+
+<div class="figcenter" style="width: 300px;margin-top:2em;">
+<a href="images/frontispiece-full.png"><img src="images/frontispiece.png" width="300" height="436" alt="Some early medical entomology. Athanasius Kircher&#39;s illustration of the Italian tarantula
+and the music prescribed as an antidote for the poison of its bite. (1643)." title="Some early medical entomology. Athanasius Kircher&#39;s illustration of the Italian tarantula
+and the music prescribed as an antidote for the poison of its bite. (1643)." /></a>
+<span class="caption">Some early medical entomology. Athanasius Kircher&#39;s illustration of the Italian tarantula
+and the music prescribed as an antidote for the poison of its bite. (1643).</span>
+</div>
+
+
+
+
+<hr style="width: 65%;" />
+<h1>HANDBOOK OF MEDICAL
+ENTOMOLOGY</h1>
+
+<h2>WM. A. RILEY, <span class="smcap">Ph.D.</span></h2>
+
+<p class="center">Professor of Insect Morphology and Parasitology, Cornell University</p>
+
+<p class="center">and</p>
+
+<h2>O. A. JOHANNSEN, <span class="smcap">Ph.D.</span></h2>
+
+<p class="center">Professor of Biology, Cornell University</p>
+
+<div class="figcenter" style="width: 125px;">
+<img src="images/tpage.png" width="125" height="152" alt="" title="" />
+</div>
+
+<p class="center">ITHACA, NEW YORK</p>
+
+<p class="center">THE COMSTOCK PUBLISHING COMPANY</p>
+
+<p class="center">1915</p>
+
+
+<p class="center">COPYRIGHT, 1915</p>
+
+<p class="center">BY THE COMSTOCK PUBLISHING COMPANY,</p>
+
+<p class="center">ITHACA, N. Y.</p>
+
+
+<p class="center">Press of W.&nbsp;F. Humphrey<br />
+Geneva, N. Y.</p>
+<p><span class="pagenum"><a name="Page_v" id="Page_v">[Pg v]</a></span></p>
+
+
+
+
+<hr style="width: 65%;" />
+<h2>PREFACE</h2>
+
+
+<p>The Handbook of Medical Entomology is the outgrowth of a
+course of lectures along the lines of insect transmission and
+dissemination of diseases of man given by the senior author
+in the Department of Entomology of Cornell University during the
+past six years. More specifically it is an illustrated revision and
+elaboration of his "Notes on the Relation of Insects to Disease"
+published January, 1912.</p>
+
+<p>Its object is to afford a general survey of the field, and primarily
+to put the student of medicine and entomology in touch with the
+discoveries and theories which underlie some of the most important
+modern work in preventive medicine. At the same time the older
+phases of the subject&mdash;the consideration of poisonous and parasitic
+forms&mdash;have not been ignored.</p>
+
+<p>Considering the rapid shifts in viewpoint, and the development
+of the subject within recent years, the authors do not indulge in any
+hopes that the present text will exactly meet the needs of every
+one specializing in the field,&mdash;still less do they regard it as complete
+or final. The fact that the enormous literature of isolated articles is
+to be found principally in foreign periodicals and is therefore difficult
+of access to many American workers, has led the authors to hope
+that a summary of the important advances, in the form of a reference
+book may not prove unwelcome to physicians, sanitarians and
+working entomologists, and to teachers as a text supplementing
+lecture work in the subject.</p>
+
+<p>Lengthy as is the bibliography, it covers but a very small fraction
+of the important contributions to the subject. It will serve only to
+put those interested in touch with original sources and to open up
+the field. Of the more general works, special acknowledgment
+should be made to those of Banks, Brumpt, Castellani and Chalmers,
+Comstock, Hewitt, Howard, Manson, Mense, Neveau-Lemaire,
+Nuttall, and Stiles.</p>
+
+<p>To the many who have aided the authors in the years past, by
+suggestions and by sending specimens and other materials, sincerest
+thanks is tendered. This is especially due to their colleagues in
+the Department of Entomology of Cornell University, and to Professor
+Charles&nbsp;W. Howard, Dr. John Uri Lloyd, Mr. A.&nbsp;H. Ritchie,
+Dr. I.&nbsp;M. Unger, and Dr. Luzerne Coville.<span class="pagenum"><a name="Page_vi" id="Page_vi">[Pg vi]</a></span></p>
+
+<p>They wish to express indebtedness to the authors and publishers
+who have so willingly given permission to use certain illustrations.
+Especially is this acknowledgment due to Professor John Henry
+Comstock, Dr. L.&nbsp;O. Howard, Dr. Graham-Smith, and Professor
+G.&nbsp;H.&nbsp;T. Nuttall. Professor Comstock not only authorized the use
+of departmental negatives by the late Professor M.&nbsp;V. Slingerland
+(credited as M.&nbsp;V.&nbsp;S.), but generously put at their disposal the illustrations
+from the <span class="smcap">Manual for the Study of Insects</span> and from
+the <span class="smcap">Spider Book</span>. Figures <a href="#Fig_5">5</a> and <a href="#Fig_111">111</a> are from Peter's "Der Arzt
+und die <a name="AC_1" id="AC_1"><span title="for Heilkunft read Heilkunst">Heilkunft</span></a> in der deutschen Vergangenheit." It should be
+noted that on examining the original, it is found that Gottfried's
+figure relates to an event antedating the typical epidemic of dancing
+mania.</p>
+
+<div style="margin-left: 75%;"><p><span class="smcap">Wm.&nbsp;A. Riley.</span><br />
+<span class="smcap">O.&nbsp;A. Johannsen.</span></p></div>
+
+<div style="margin-left: 2em;"><p><span class="smcap">Cornell University</span>,<br />
+January, 1915.</p></div>
+
+
+
+
+<hr style="width: 65%;" />
+<h2>ADDITIONS AND CORRECTIONS</h2>
+
+
+<div class="hanging"><p>vi <a href="#AC_1">line 11</a>, for Heilkunft read Heilkunst.</p>
+
+<p>18 <a href="#AC_2">line 2</a>, for tarsi read tarsus.</p>
+
+<p>32 <a href="#AC_3">line 21</a>, and legend under <a href="#Fig_23">fig.&nbsp;23</a>, for C. (Conorhinus)
+abdominalis read Melanolestes abdominalis.</p>
+
+<p>47 legend under <a href="#Fig_33c">figure</a> for 33c read 34.</p>
+
+<p>92 line <a href="#AC_5a">22</a> and <a href="#AC_5b">25</a>, for sangiusugus read sanguisugus.</p>
+
+<p>116 legend under <a href="#Fig_83">fig.&nbsp;83</a>, for Graham-Smith read Manson.</p>
+
+<p>136 <a href="#AC_7">line 10, from bottom</a>, insert "ring" after "chitin".</p>
+
+<p>137 <a href="#AC_8">line 3</a>, for meditatunda read meditabunda.</p>
+
+<p>145 <a href="#AC_9">line 7, from bottom</a>, for Rs read R<sub>5</sub>.</p>
+
+<p>158 <a href="#AC_10">line 20</a>, for have read has.</p>
+
+<p>212 after the <a href="#CHAPTER_IX">chapter heading</a> insert "continued".</p>
+
+<p>219 <a href="#AC_12">line 10, from bottom</a>, for Cornohinus read Conorhinus.</p>
+
+<p>266 <a href="#AC_13">line 1</a>, <a href="#Fig_158">fig.&nbsp;158j</a> refers to the female.</p>
+
+<p>272 <a href="#AC_14">line 5</a>, insert "palpus" before "and leg".</p>
+
+<p>281 <a href="#AC_15">line 6</a>, for discodial read discoidal.</p>
+
+<p>281 <a href="#AC_16">last line</a>, insert "from" before "the".</p>
+
+<p>284 <a href="#AC_17">line 5</a>, for "tubercle of" read "tubercle or".</p>
+
+<p>305 lines <a href="#AC_18a">19</a>, <a href="#AC_18b">28</a>, <a href="#AC_18c">44</a>, page 306 lines <a href="#AC_18d">1</a>, <a href="#AC_18e">9</a>, <a href="#AC_18f">22</a>, <a href="#AC_18g">27</a>, <a href="#AC_18h">30</a>, page 307 <a href="#AC_18i">line 7</a>,
+page 309 lines <a href="#AC_18j">8</a>, <a href="#AC_18k">11</a>, for R<sub>4+5</sub> read M<sub>1+2</sub>.</p>
+
+<p>309 legend under <a href="#Fig_168">fig.&nbsp;168</a> add Bureau of Entomology.</p>
+
+<p>312 <a href="#AC_20">line 36</a>, for "near apex" read "of M<sub>1+2</sub>".</p>
+
+<p>313 running head, for Muscidæ read Muscoidea.</p>
+
+<p>314 <a href="#AC_22">line 29</a>, for "distal section" read "distally M<sub>1+2</sub>".</p>
+
+<p>315 legend under <a href="#Fig_172">fig.&nbsp;172</a>, for Pseudopyrellia read Orthellia,
+for Lyperosia read Hæmatobia, for Umbana read urbana.</p>
+
+<p><a href="#Fig_173">323</a> and <a href="#Fig_174">325</a> legends under the figures, add "After Dr. J.&nbsp;H.
+Stokes".</p>
+
+<p>328 <a href="#AC_25">line 7 from bottom</a> for Apiochæta read Aphiochæta.</p></div><p><span class="pagenum"><a name="Page_vii" id="Page_vii">[Pg vii]</a></span></p>
+
+
+
+<hr style="width: 65%;" />
+<h2>CONTENTS</h2>
+
+
+<pre>
+<a href="#CHAPTER_I"><b>CHAPTER I</b></a>
+
+<a href="#CHAPTER_I"><b>INTRODUCTION</b></a>                                                 <a href="#Page_1">1-5</a>
+
+  <a href="#EARLY_SUGGESTIONS_REGARDING_THE_TRANSMISSION_OF_DISEASE_BY_INSECTS">Early suggestions regarding the transmission of disease by</a>
+    <a href="#EARLY_SUGGESTIONS_REGARDING_THE_TRANSMISSION_OF_DISEASE_BY_INSECTS">insects.</a>
+  <a href="#THE_WAYS_IN_WHICH_ARTHROPODS_MAY_AFFECT_THE_HEALTH_OF_MAN">The ways in which arthropods may affect the health of man.</a>
+
+
+<a href="#CHAPTER_II"><b>CHAPTER II</b></a>
+
+<a href="#CHAPTER_II"><b>ARTHROPODS WHICH ARE DIRECTLY POISONOUS</b></a>                       <a href="#Page_6">6-56</a>
+
+  <a href="#ARANEIDA_OR_SPIDERS">The Araneida, or Spiders.</a>
+    <a href="#The_Tarantulas">The tarantulas.</a> <a href="#Avicularoidea">Bird spiders.</a> <a href="#Spiders_of_the_Genus_Latrodectus">Spiders of the genus</a>
+      <a href="#Spiders_of_the_Genus_Latrodectus">Latrodectus.</a> <a href="#Other_Venomous_Spiders">Other venomous spiders.</a> <a href="#Summary">Summary.</a>
+  <a href="#THE_PEDIPALPIDA_OR_WHIP-SCORPIONS">The Pedipalpida, or whip-scorpions.</a>
+  <a href="#THE_SCORPIONIDA_OR_TRUE_SCORPIONS">The Scorpionida, or true scorpions.</a>
+  <a href="#THE_SOLPUGIDA_OR_SOLPUGIDS">The Solpugida, or solpugids.</a>
+  <a href="#THE_ACARINA_OR_MITES_AND_TICKS">The Acarina, or mites and ticks.</a>
+  <a href="#THE_MYRIAPODA_OR_CENTIPEDES_AND_MILLIPEDES">The Myriapoda, or centipedes and millipedes.</a>
+  <a href="#THE_HEXAPODA_OR_TRUE_INSECTS">The Hexapoda, or true insects.</a>
+    <a href="#PIERCING_OR_BITING_INSECTS_POISONOUS_TO_MAN">Piercing or biting insects poisonous to man.</a>
+      <a href="#Hemiptera">Hemiptera, or true bugs.</a>
+        <a href="#The_Notonectidae_or_back_swimmers">The Notonectidæ or back-swimmers.</a> <a href="#The_Belostomatidae_or_giant_water_bugs">Belostomidæ or giant</a>
+          <a href="#The_Belostomatidae_or_giant_water_bugs">water-bugs.</a> <a href="#The_Reduviidae_or_assassin-bugs">Reduviidæ, or assassin bugs.</a> <a href="#Other_Hemiptera_Reported_as_Poisonous_to_Man">Other</a>
+          <a href="#Other_Hemiptera_Reported_as_Poisonous_to_Man">Hemiptera reported as poisonous to man.</a>
+      <a href="#DIPTERA">Diptera; the midges, mosquitoes and flies.</a>
+    <a href="#STINGING_INSECTS">Stinging insects.</a>
+      <a href="#Apis_mellifica_the_honey_bee">Apis mellifica, the honey bee.</a> <a href="#Other_Stinging_Forms">Other stinging forms.</a>
+    <a href="#NETTLING_INSECTS">Nettling insects.</a>
+      <a href="#LEPIDOPTERA">Lepidoptera, or butterflies and moths.</a> <a href="#Relief_from_Poisoning_by_Nettling_Larvae">Relief from</a>
+        <a href="#Relief_from_Poisoning_by_Nettling_Larvae">poisoning by nettling larvæ.</a>
+    <a href="#Vescicating_Insects_and_those_Possessing_Other_Poisons_in_their_Blood_Plasma">Vescicating insects and those possessing other poisons</a>
+      <a href="#Vescicating_Insects_and_those_Possessing_Other_Poisons_in_their_Blood_Plasma">in their blood plasma.</a> <a href="#The_Blister_Beetles">The blister beetles.</a> <a href="#Other_Cryptotoxic_Insects">Other</a>
+      <a href="#Other_Cryptotoxic_Insects">cryptotoxic insects.</a>
+
+
+<a href="#CHAPTER_III"><b>CHAPTER III</b></a>
+
+<a href="#CHAPTER_III"><b>PARASITIC ARTHROPODS AFFECTING MAN</b></a>                            <a href="#Page_57">57-130</a>
+
+  <a href="#Acarina_or_Mites">Acarina, or mites.</a>
+    <a href="#The_Trombidiidae_or_Harvest_Mites">The Trombidiidæ, or harvest mites.</a>
+    <a href="#Ixodoidea_or_Ticks">The Ixodoidea, or ticks.</a>
+      <a href="#Argasidae">Argasidæ.</a> <a href="#Ixodidae">Ixodidæ.</a> <a href="#Treatment_of_Tick_Bites">Treatment of tick bites.</a>
+    <a href="#Dermanyssidae">The mites.</a>
+      <a href="#Dermanyssidae">Dermanyssidæ.</a> <a href="#Tarsonemidae">Tarsonemidæ.</a> <a href="#Sarcoptidae">Sarcoptidæ, the itch mites.</a>
+        <a href="#Demodecidae">Demodecidæ, the follicle mites.</a>
+  <a href="#Hexapoda_or_True_Insects">Hexapoda, or true insects.</a>
+    <a href="#Siphunculata">Siphunculata, or sucking lice.</a>
+    <a href="#Hemiptera">Hemiptera.</a><span class="pagenum"><a name="Page_viii" id="Page_viii">[Pg viii]</a></span>
+    <a href="#The_Bed-bugs">The bed-bug.</a> <a href="#Other_Bed-bugs">Other bed-bugs.</a>
+  <a href="#Parasitic_Diptera_or_Flies">Parasitic Diptera, or flies.</a>
+    <a href="#Psychodidae_or_Moth-Flies">Psychodidæ, or moth flies.</a> <a href="#The_Phlebotominae">Phlebotominæ.</a> <a href="#Culicidae_or_Mosquitoes">Culicidæ, or</a>
+      <a href="#Culicidae_or_Mosquitoes">mosquitoes.</a> <a href="#The_Simuliidae_or_Black_Flies">Simuliidæ, or black-flies.</a> <a href="#Chironomidae_or_Midges">Chironomidæ, or</a>
+      <a href="#Chironomidae_or_Midges">midges.</a> <a href="#Tabanidae_or_Horse-Flies">Tabanidæ, or horse-flies.</a> <a href="#Leptidae_or_Snipe-Flies">Leptidæ or</a>
+      <a href="#Leptidae_or_Snipe-Flies">snipe-flies.</a> <a href="#Oestridae_or_Bot-flies">Oestridæ, or bot-flies.</a> <a href="#Muscidae">Muscidæ, the</a>
+      <a href="#Muscidae">stable-fly and others.</a>
+  <a href="#The_Siphonaptera_or_Fleas">Siphonaptera, or fleas.</a>
+    <a href="#The_Siphonaptera_or_Fleas">The fleas affecting man, the dog, cat, and rat.</a>
+    <a href="#The_true_chiggers">The true chiggers, or chigoes.</a>
+
+<a href="#CHAPTER_IV"><b>CHAPTER IV</b></a>
+
+<a href="#CHAPTER_IV"><b>ACCIDENTAL OR FACULTATIVE PARASITES</b></a>                           <a href="#Page_131">131-143</a>
+
+  <a href="#Acarina">Acarina, or mites.</a>
+  <a href="#Myriapoda">Myriapoda, or centipedes and millipedes.</a>
+  <a href="#Lepidopterous_Larvae">Lepidopterous larvæ.</a>
+  <a href="#Coleoptera">Coleoptera, or beetles.</a>
+  <a href="#Dipterous_Larvae">Dipterous larvæ causing myiasis.</a>
+    <a href="#Piophila_casei">Piophila casei, the cheese skipper.</a> <a href="#Chrysomyia_macellaria">Chrysomyia macellaria,</a>
+      <a href="#Chrysomyia_macellaria">the screw-worm fly.</a> <a href="#Calliphorinae">Calliphorinæ, the bluebottles.</a>
+      <a href="#Muscinae">Muscinæ, the house or typhoid fly, and others.</a>
+      <a href="#Anthyomyiidae">Anthomyiidæ, the lesser house-fly and others.</a>
+      <a href="#Sarcophagidae">Sarcophagidæ, the flesh-flies.</a>
+
+
+<a href="#CHAPTER_V"><b>CHAPTER V</b></a>
+
+<a href="#CHAPTER_V"><b>ARTHROPODS AS SIMPLE CARRIERS OF DISEASE</b></a>                      <a href="#Page_144">144-163</a>
+
+  <a href="#The_House-fly_As_a_Carrier_of_Disease">The house or typhoid fly as a carrier of disease.</a>
+  <a href="#Stomoxys_calcitrans_the_stable-fly">Stomoxys calcitrans, the stable-fly.</a>
+  <a href="#Other_arthropods_which_may_serve_as_simple_carriers_of_pathogenic_organisms">Other arthropods which may serve as simple carriers of</a>
+    <a href="#Other_arthropods_which_may_serve_as_simple_carriers_of_pathogenic_organisms">pathogenic organisms.</a>
+
+
+<a href="#CHAPTER_VI"><b>CHAPTER VI</b></a>
+
+<a href="#CHAPTER_VI"><b>ARTHROPODS AS DIRECT INOCULATORS OF DISEASE GERMS</b></a>             <a href="#Page_164">164-174</a>
+
+  <a href="#Some_Illustrations_of_Direct_Inoculation_of_Disease_Germs_by_Arthropods">Some illustrations of direct inoculations of disease germs</a>
+    <a href="#Some_Illustrations_of_Direct_Inoculation_of_Disease_Germs_by_Arthropods">by arthropods.</a>
+  <a href="#The_Role_of_Fleas_in_the_Transmission_of_the_Plague">The rôle of fleas in the transmission of the plague.</a>
+
+
+<a href="#CHAPTER_VII"><b>CHAPTER VII</b></a>
+
+<a href="#CHAPTER_VII"><b>ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC ORGANISMS</b></a>         <a href="#Page_175">175-185</a>
+
+  <a href="#Insects_as_Intermediate_Hosts_of_Tapeworms">Insects as intermediate hosts of tape-worms.</a>
+  <a href="#Arthropods_as_Intermediate_Hosts_of_Nematode_Worms">Arthropods as intermediate hosts of nematode worms.</a>
+    <a href="#Filariasis_and_Mosquitoes">Filariasis and mosquitoes.</a>
+  <a href="#Other_Nematode_Parasites_of_Man_and_Animals_Developing_in_Arthropods">Other nematode parasites of man and animals.</a>
+
+
+<a href="#CHAPTER_VIII"><b>CHAPTER VIII</b></a>
+
+<a href="#CHAPTER_VIII"><b>ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA</b></a>          <a href="#Page_186">186-211</a>
+
+  <a href="#Mosquitoes_and_Malaria">Mosquitoes and malaria.</a>
+  <a href="#Mosquitoes_and_Yellow_Fever">Mosquitoes and yellow fever.</a><span class="pagenum"><a name="Page_ix" id="Page_ix">[Pg ix]</a></span>
+
+
+<a href="#CHAPTER_IX"><b>CHAPTER IX</b></a>
+
+<a href="#CHAPTER_IX"><b>ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA</b></a>          <a href="#Page_212">212-229</a>
+
+  <a href="#Insects_and_Trypanosomiases">Insects and trypanosomiases.</a>
+    <a href="#Fleas_and_Lice_as_Carriers_of_Trypanosoma_lewisi">Fleas and lice as carriers of Trypanosoma lewisi.</a>
+    <a href="#Tsetse-flies_and_Nagana">Tsetse-flies and nagana.</a>
+    <a href="#Tsetse-flies_and_Sleeping_Sickness_of_Man">Tsetse-flies and sleeping sickness in man.</a>
+    <a href="#South_American_Trypanosomiasis">South American trypanosomiasis.</a>
+    <a href="#Leishmanioses_and_Insects">Leishmanioses and insects.</a>
+  <a href="#Ticks_and_Diseases_of_Man_and_Animals">Ticks and diseases of man and animals.</a>
+    <a href="#Cattle_Ticks_and_Texas_Fever">Cattle tick and Texas fever.</a>
+    <a href="#Ticks_and_Rocky_Mountain_Spotted_Fever_of_Man">Ticks and Rocky Mountain Spotted fever of man.</a>
+
+
+<a href="#CHAPTER_X"><b>CHAPTER X</b></a>
+
+<b><a href="#CHAPTER_X">ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA</a>
+<a href="#CHAPTER_X">(Continued)</a></b>                                                   <a href="#Page_230">230-240</a>
+
+  <a href="#Arthropods_and_Spirochaetoses_of_Man_and_Animals">Arthropods and Spirochætoses of man and animals.</a>
+    <a href="#African_Relapsing_Fever_of_Man">African relapsing fever of man.</a>
+    <a href="#European_Relapsing_Fever">European relapsing fever.</a>
+    <a href="#North_African_Relapsing_Fever_of_Man">North African relapsing fever of man.</a>
+    <a href="#Other_Types_of_Relapsing_Fever_of_Man">Other types of relapsing fever of man.</a>
+    <a href="#Spirochaetosis_of_Fowls">Spirochætosis of fowls.</a>
+    <a href="#Other_Spirochaete_Diseases_of_Animals">Other spirochæte diseases of animals.</a>
+  <a href="#Typhus_Fever_and_Pediculidae">Typhus fever and lice.</a>
+
+
+<a href="#CHAPTER_XI"><b>CHAPTER XI</b></a>
+
+<b><a href="#CHAPTER_XI">SOME POSSIBLE, BUT IMPERFECTLY KNOWN CASES OF</a>
+<a href="#CHAPTER_XI">ARTHROPOD TRANSMISSION OF DISEASE</a></b>                             <a href="#Page_241">241-256</a>
+
+  <a href="#Infantile_Paralysis_or_Acute_Anterior_Poliomyelitis">Infantile paralysis, or acute anterior poliomyelitis.</a>
+  <a href="#Pellagra">Pellagra.</a> <a href="#Leprosy">Leprosy.</a> <a href="#Verruga_peruviana">Verruga peruviana.</a> <a href="#Cancer">Cancer.</a>
+
+
+<a href="#CHAPTER_XII"><b>CHAPTER XII</b></a>
+
+<a href="#CHAPTER_XII"><b>KEYS TO THE ARTHROPODS NOXIOUS TO MAN</b></a>                         <a href="#Page_257">257-317</a>
+
+  <a href="#CRUSTACEA">Crustacea.</a>
+  <a href="#MYRIAPODA_1">Myriapoda, or centipedes and millipedes.</a>
+  <a href="#ORDERS_OF_THE_ARACHNIDA">Arachnida (Orders of).</a>
+    <a href="#ACARINA_KEY">Acarina or ticks.</a>
+  <a href="#HEXAPODA_Insecta">Hexapoda (Insecta).</a>
+    <a href="#SIPHUNCULATA_AND_HEMIPTERA">Siphunculata and Hemiptera (lice and true bugs).</a>
+    <a href="#DIPTERA_Mosquitoes_Midges_Flies">Diptera (mosquitoes, midges, and flies).</a>
+    <a href="#SIPHONAPTERA_Fleas">Siphonaptera (fleas).</a>
+
+
+<a href="#APPENDIX"><b>APPENDIX</b></a>
+
+<a href="#HYDROCYANIC_ACID_GAS_AGAINST_HOUSEHOLD_INSECTS">Hydrocyanic acid gas against household insects</a>                <a href="#Page_318">318-320</a>
+  <a href="#The_Proportions_of_Ingredients">Proportion of ingredients.</a> <a href="#A_Single_Room_As_an_Example">A single room as an example.</a>
+    <a href="#Fumigating_a_Large_House">Fumigating a large house.</a> <a href="#Precautions">Precautions.</a>
+
+<a href="#LESIONS_PRODUCED_BY_THE_BITE_OF_THE_BLACK-FLY">Lesions produced by the bite of the black-fly</a>                 <a href="#Page_321">321-326</a>
+
+
+<a href="#BIBLIOGRAPHY"><b>BIBLIOGRAPHY</b></a>                                                  <a href="#Page_327">327-340</a>
+
+
+<a href="#INDEX"><b>INDEX</b></a>                                                         <a href="#Page_341">341-348</a><span class="pagenum"><a name="Page_1" id="Page_1">[Pg 1]</a></span></pre>
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="CHAPTER_I" id="CHAPTER_I"></a>CHAPTER I.</h2>
+
+<h2>INTRODUCTION</h2>
+
+
+<a name="EARLY_SUGGESTIONS_REGARDING_THE_TRANSMISSION_OF_DISEASE_BY_INSECTS" id="EARLY_SUGGESTIONS_REGARDING_THE_TRANSMISSION_OF_DISEASE_BY_INSECTS"></a><h3>EARLY SUGGESTIONS REGARDING THE TRANSMISSION OF DISEASE
+BY INSECTS</h3>
+
+<p>Until very recent years insects and their allies have been considered
+as of economic importance merely in so far as they are an annoyance
+or direct menace to man, or his flocks and herds, or are injurious to
+his crops. It is only within the past fifteen years that there has
+sprung into prominence the knowledge that in another and much more
+insiduous manner, they may be the enemy of mankind, that they
+may be among the most important of the disseminators of disease.
+In this brief period, such knowledge has completely revolutionized
+our methods of control of certain diseases, and has become an important
+weapon in the fight for the conservation of health.</p>
+
+<p>It is nowhere truer than in the case under consideration that however
+abrupt may be their coming into prominence, great movements
+and great discoveries do not arise suddenly. Centuries ago
+there was suggested the possibility that insects were concerned with
+the spread of disease, and from time to time there have appeared keen
+suggestions and logical hypotheses along this line, that lead us to
+marvel that the establishment of the truths should have been so long
+delayed.</p>
+
+<p>One of the earliest of these references is by the Italian physician,
+Mercurialis, who lived from 1530 to 1607, during a period when
+Europe was being ravaged by the dread "black death", or plague.
+Concerning its transmission he wrote: "There can be no doubt that
+flies feed on the internal secretions of the diseased and dying, then,
+flying away, they deposit their excretions on the food in neighboring
+dwellings, and persons who eat of it are thus infected."</p>
+
+<p>It would be difficult to formulate more clearly this aspect of the
+facts as we know them to-day, though it must always be borne in
+mind that we are prone to interpret such statements in the light of
+present-day knowledge. Mercurialis had no conception of the animate
+nature of contagion, and his statement was little more than a lucky
+guess.</p>
+
+<p>Much more worthy of consideration is the approval which was
+given to his view by the German Jesuit, Athanasius Kircher in 1658.<span class="pagenum"><a name="Page_2" id="Page_2">[Pg 2]</a></span>
+One cannot read carefully his works without believing that long
+before Leeuwenhook's discovery, Kircher had seen the larger species of
+bacteria. Moreover, he attributed the production of disease to these
+organisms and formulated, vaguely, to be sure, a theory of the animate
+nature of contagion. It has taken two and a half centuries to
+accumulate the facts to prove his hypothesis.</p>
+
+<p>The theory of Mercurialis was not wholly lost sight of, for in the
+medical literature of the eighteenth century there are scattered
+references to flies as carriers of disease. Such a view seems even to
+have been more or less popularly accepted, in some cases. Gudger
+(1910), has pointed out that, as far back as 1769, Edward Bancroft,
+in "An Essay on the Natural History of Guiana in South America,"
+wrote concerning the contagious skin-disease known as "Yaws":
+"It is usually believed that this disorder is communicated by the flies
+who have been feasting on a diseased object, to those persons who have
+sores, or scratches, which are uncovered; and from many observations,
+I think this is not improbable, as none ever receive this disorder
+whose skins are whole."</p>
+
+<p>Approaching more closely the present epoch, we find that in 1848,
+Dr. Josiah Nott, of Mobile, Alabama, published a remarkable
+article on the cause of yellow fever, in which he presented "reasons for
+supposing its specific cause to exist in some form of insect life."
+As a matter of fact, the bearing of Nott's work on present day ideas
+of the insect transmission of disease has been very curiously overrated.
+The common interpretation of his theory has been deduced from a few
+isolated sentences, but his argument appears quite differently when
+the entire article is studied. It must be remembered that he wrote at
+a period before the epoch-making discoveries of Pasteur and before
+the recognition of micro-organisms as factors in the cause of disease.
+His article is a masterly refutation of the theory of "malarial" origin
+of "all the fevers of hot climates," but he uses the term "insect" as
+applicable to the lower forms of life, and specific references to "mosquitoes,"
+"aphids," "cotton-worms," and others, are merely in the
+way of similes.</p>
+
+<p>But, while Nott's ideas regarding the relation of insects to yellow
+fever were vague and indefinite, it was almost contemporaneously
+that the French physician, Louis Daniel Beauperthuy argued in the
+most explicit possible manner, that yellow fever and various others
+are transmitted by mosquitoes. In the light of the data which were
+available when he wrote, in 1853, it is not surprising that he erred by<span class="pagenum"><a name="Page_3" id="Page_3">[Pg 3]</a></span>
+thinking that the source of the virus was decomposing matter which
+the mosquito took up and accidentally inoculated into man. Beauperthuy
+not only discussed the rôle of mosquitoes in the transmission
+of disease, but he taught, less clearly, that house-flies scatter pathogenic
+organisms. It seems that Boyce (1909) who quotes extensively
+from this pioneer work, does not go too far when he says "It is Dr.
+Beauperthuy whom we must regard as the father of the doctrine of
+insect-borne disease."</p>
+
+<p>In this connection, mention must be made of the scholarly article
+by the American physician, A.&nbsp;F.&nbsp;A. King who, in 1883, brought
+together an all but conclusive mass of argument in support of his
+belief that malaria was caused by mosquitoes. At about the same
+time, Finley, of Havana, was forcefully presenting his view that the
+mosquito played the chief rôle in the spread of yellow fever.</p>
+
+<p>To enter more fully into the general historical discussion is beyond
+the scope of this book. We shall have occasion to make more
+explicit references in considering various insect-borne diseases.
+Enough has been said here to emphasize that the recognition of
+insects as factors in the spread of disease was long presaged, and that
+there were not wanting keen thinkers who, with a background of
+present-day conceptions of the nature of disease, might have been in
+the front rank of investigators along these lines.</p>
+
+
+<a name="THE_WAYS_IN_WHICH_ARTHROPODS_MAY_AFFECT_THE_HEALTH_OF_MAN" id="THE_WAYS_IN_WHICH_ARTHROPODS_MAY_AFFECT_THE_HEALTH_OF_MAN"></a><h3>THE WAYS IN WHICH ARTHROPODS MAY AFFECT THE HEALTH
+OF MAN</h3>
+
+<p>When we consider the ways in which insects and their allies may
+affect the health of man, we find that we may treat them under three
+main groups:</p>
+
+<p>A. They may be directly poisonous. Such, for example, are the
+scorpions, certain spiders and mites, some of the predaceous bugs,
+and stinging insects. Even such forms as the mosquito deserve
+some consideration from this viewpoint.</p>
+
+<p>B. They may be parasitic, living more or less permanently on
+or in the body and deriving their sustenance from it.</p>
+
+<p>Of the parasitic arthropods we may distinguish, first, the <i>true
+parasites</i>, those which have adopted and become confirmed in the
+parasitic habit. Such are the itch mites, the lice, fleas, and the
+majority of the forms to be considered as parasitic.</p>
+
+<p>In addition to these, we may distinguish a group of <i>accidental</i>, or
+<i>facultative parasites</i>, species which are normally free-living, feeding on<span class="pagenum"><a name="Page_4" id="Page_4">[Pg 4]</a></span>
+decaying substances, but which when accidentally introduced into
+the alimentary canal or other cavities of man, may exist there
+for a greater or less period. For example, certain fly larvæ, or maggots,
+normally feeding in putrifying meat, have been known to occur
+as accidental or facultative parasites in the stomach of man.</p>
+
+<p>C. Finally, and most important, arthropods may be transmitters
+and disseminators of disease. In this capacity they may
+function in one of three ways; as <i>simple carriers</i>, as <i>direct inoculators</i>,
+or as <i>essential hosts</i> of disease germs.</p>
+
+<p>As simple carriers, they may, in a wholly incidental manner,
+transport from the diseased to the healthy, or from filth to food,
+pathogenic germs which cling to their bodies or appendages. Such,
+for instance, is the relation of the house-fly to the dissemination of
+typhoid.</p>
+
+<p>As direct inoculators, biting or piercing species may take up from
+a diseased man or animal, germs which, clinging to the mouth parts,
+are inoculated directly into the blood of the insect's next victim. It
+it thus that horse-flies may occasionally transmit anthrax. Similarly,
+species of spiders and other forms which are ordinarily perfectly
+harmless, may accidentally convey and inoculate pyogenic bacteria.</p>
+
+<p>It is as essential hosts of disease germs that arthropods play their
+most important rôle. In such cases an essential part of the life cycle
+of the pathogenic organism is undergone in the insect. In other
+words, without the arthropod host the disease-producing organism
+cannot complete its development. As illustrations may be cited the
+relation of the Anopheles mosquito to the malarial parasite, and the
+relation of the cattle tick to Texas fever.</p>
+
+<p>A little consideration will show that this is the most important of
+the group. Typhoid fever is carried by water or by contaminated
+milk, and in various other ways, as well as by the house-fly. Kill all
+the house-flies and typhoid would still exist. On the other hand,
+malaria is carried only by the mosquito, because an essential part of
+the development of the malarial parasite is undergone in this insect.
+Exterminate all of the mosquitoes of certain species and the dissemination
+of human malaria is absolutely prevented.</p>
+
+<p>Once an arthropod becomes an essential host for a given parasite
+it may disseminate infection in three different ways:</p>
+
+<p>1. By infecting man or animals who ingest it. It is thus, for
+example, that man, dog, or cat, becomes infected with the double-pored
+dog tapeworm, <i>Dipylidium caninum</i>. The cysticercoid stage<span class="pagenum"><a name="Page_5" id="Page_5">[Pg 5]</a></span>
+occurs in the dog louse, or in the dog or cat fleas, and by accidentally
+ingesting the infested insect the vertebrate becomes infested. Similarly,
+<i>Hymenolepis diminuta</i>, a common tapeworm of rats and mice,
+and occasional in man, undergoes part of its life cycle in various meal-infesting
+insects, and is accidentally taken up by its definitive host.
+It is very probable that man becomes infested with <i>Dracunculus
+(Filaria) medinensis</i> through swallowing in drinking water, the
+crustacean, <i>Cyclops</i>, containing the larvæ of this worm.</p>
+
+<p>2. By infecting man or animals on whose skin or mucous membranes the
+insect host may be crushed or may deposit its excrement.
+The pathogenic organism may then actively penetrate, or may be
+inoculated by scratching. The causative organism of typhus fever
+is thus transmitted by the body louse.</p>
+
+<p>3. By direct inoculation by its bite, the insect host may transfer
+the parasite which has undergone development within it. The
+malarial parasite is thus transferred by mosquitoes; the Texas fever
+parasite by cattle ticks.<span class="pagenum"><a name="Page_6" id="Page_6">[Pg 6]</a></span></p>
+
+
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="CHAPTER_II" id="CHAPTER_II"></a>CHAPTER II.</h2>
+
+<h2>ARTHROPODS WHICH ARE DIRECTLY POISONOUS</h2>
+
+
+<p>Of all the myriads of insects and related forms, a very few are of
+direct use to man, some few others have forced his approbation on
+account of their wonderful beauty, but the great hordes of them are
+loathed or regarded as directly dangerous. As a matter of fact, only
+a very small number are in the slightest degree poisonous to man or
+to the higher animals. The result is that entomologists and lovers
+of nature, intent upon dissipating the foolish dread of insects, are
+sometimes inclined to go to the extreme of discrediting all statements
+of serious injury from the bites or stings of any species.</p>
+
+<p>Nevertheless, it must not be overlooked that poisonous forms do
+exist, and they must receive attention in a consideration of the ways
+in which arthropods may affect the health of man. Moreover, it
+must be recognized that "what is one man's meat, is another man's
+poison," and that in considering the possibilities of injury we must not
+ignore individual idiosyncrasies. Just as certain individuals may be
+poisoned by what, for others, are common articles of food, so some
+persons may be abnormally susceptible to insect poison. Thus, the
+poison of a bee sting may be of varying severity, but there are individuals
+who are made seriously sick by a single sting, regardless of the
+point of entry. Some individuals scarcely notice a mosquito bite,
+others find it very painful, and so illustrations of this difference in
+individuals might be multiplied.</p>
+
+<p>In considering the poisonous arthropods, we shall take them up by
+groups. The reader who is unacquainted with the systematic relationship
+of insects and their allies is referred to <a href="#CHAPTER_XII">Chapter&nbsp;XII</a>. No
+attempt will be made to make the lists under the various headings
+exhaustive, but typical forms will be discussed.</p>
+
+
+<a name="ARANEIDA_OR_SPIDERS" id="ARANEIDA_OR_SPIDERS"></a><h3>ARANEIDA OR SPIDERS</h3>
+
+<p>Of all the arthropods there are none which are more universally
+feared than are the spiders. It is commonly supposed that the
+majority, if not all the species are poisonous and that they are aggressive
+enemies of man and the higher animals, as well as of lower forms.</p>
+
+<p>That they really secrete a poison may be readily inferred from the
+effect of their bite upon insects and other small forms. Moreover,<span class="pagenum"><a name="Page_7" id="Page_7">[Pg 7]</a></span>
+the presence of definite and well-developed poison glands can easily
+be shown. They occur as a pair of pouches (<a href="#Fig_1">fig.&nbsp;1</a>) lying within the
+cephalothorax and connected by a delicate
+duct with a pore on the claw of the chelicera,
+or so-called "mandible" on the convex surface
+of the claw in such a position that it is not
+plugged and closed by the flesh of the victim.</p>
+
+<div class="figleft" style="width: 300px;"><a name="Fig_1" id="Fig_1"></a>
+<a href="images/f001-full.png"><img src="images/f001.png" width="300" height="263" alt="1. Head of a spider showing
+poison gland (c) and its relation
+to the chelicera (a)." title="1. Head of a spider showing
+poison gland (c) and its relation
+to the chelicera (a)." /></a>
+<span class="caption">1. Head of a spider showing
+poison gland&nbsp;(<i>c</i>) and its relation
+to the chelicera&nbsp;(<i>a</i>).</span>
+</div>
+
+<p>The glands may be demonstrated by slowly
+and carefully twisting off a chelicera and
+pushing aside the stumps of muscles at its
+base. By exercising care, the chitinous wall
+of the chelicera and its claw may be broken
+away and the duct traced from the gland to its outlet. The inner
+lining of the sac is constituted by a highly developed glandular
+epithelium, supported by a basement membrane of connective
+tissue and covered by a muscular layer, (<a href="#Fig_2">fig.&nbsp;2</a>). The muscles, which
+are striated, are spirally arranged (<a href="#Fig_1">fig.&nbsp;1</a>), and are doubtless under
+control of the spider, so that the amount of poison to be injected into
+a wound may be varied.</p>
+
+<div class="figright" style="width: 300px;"><a name="Fig_2" id="Fig_2"></a>
+<a href="images/f002-full.png"><img src="images/f002.png" width="300" height="254" alt="2. Section through a venom
+gland of Latrodectus
+13-guttatus showing
+the peritoneal, muscular
+and epithelial layers.
+After Bordas." title="2. Section through a venom
+gland of Latrodectus
+13-guttatus showing
+the peritoneal, muscular
+and epithelial layers.
+After Bordas." /></a>
+<span class="caption">2. Section through a venom
+gland of Latrodectus
+13-guttatus showing
+the peritoneal, muscular
+and epithelial layers.
+After Bordas.</span>
+</div>
+
+<p>The poison itself, according to Kobert (1901), is a clear, colorless
+fluid, of oily consistency, acid reaction, and very bitter taste. After
+the spider has bitten two or three times, its supply is exhausted and
+therefore, as in the case of snakes, the poison of the bite decreases
+quickly with use, until it is null. To what extent the content of the
+poison sacs may contain blood serum or, at least, active principles of
+serum, in addition to a specific poison formed by the poison glands
+themselves, Kobert regards as an open question. He believes that
+the acid part of the poison, if really present,
+is formed by the glands and that,
+in the case of some spiders, the
+ferment-like, or better, active
+toxine, comes from the blood.</p>
+
+<div class="figleft" style="width: 225px;">
+<a href="images/f003-full.png"><img src="images/f003.png" width="225" height="342" alt="3. Chelicera of a
+spider." title="3. Chelicera of a
+spider." /></a>
+<span class="caption">3. Chelicera of a
+spider.</span>
+</div>
+
+<p>But there is a wide difference
+between a poison which may kill
+an insect and one which is harmful
+to men. Certain it is that
+there is no lack of popular belief
+and newspaper records of fatal
+cases, but the evidence regarding the possibility of fatal or even very
+serious results for man is most contradictory. For some years,
+we have attempted to trace the more circumstantial newspaper<span class="pagenum"><a name="Page_8" id="Page_8">[Pg 8]</a></span>
+accounts, which have come to our notice, of injury by North
+American species. The results have served, mainly, to emphasize
+the straits to which reporters are sometimes driven when
+there is a dearth of news. The accounts are usually vague and lacking
+in any definite clue for locating the supposed victim. In the
+comparatively few cases where the patient, or his physician, could
+be located, there was either no claim that the injury was due to
+spider venom, or there was no evidence to support the belief.
+Rarely, there was evidence that a secondary blood poisoning, such
+as might be brought about by the prick of a pin, or by any mechanical
+injury, had followed the bite of a spider. Such instances have
+no bearing on the question of the
+venomous nature of these forms.</p>
+
+<div class="figleft" style="width: 300px;"><a name="Fig_4" id="Fig_4"></a>
+<a href="images/f004-full.png"><img src="images/f004.png" width="300" height="321" alt="4. The Italian tarantula (Lycosa tarantula).
+After Kobert." title="4. The Italian tarantula (Lycosa tarantula).
+After Kobert." /></a>
+<span class="caption">4. The Italian tarantula (Lycosa tarantula).
+After Kobert.</span>
+</div>
+
+<p>The extreme to which unreasonable
+fear of the bites of spiders
+influenced the popular mind was
+evidenced by the accepted explanation
+of the remarkable dancing
+mania, or tarantism, of Italy during
+the Middle Ages. This was a nervous
+disorder, supposed to be due
+to the bite of a spider, the European
+tarantula (<a href="#Fig_4">fig.&nbsp;4</a>), though it was
+also, at times, attributed to the
+bite of the scorpion. In its typical
+form, it was characterized by so
+great a sensibility to music that under its influence the victims
+indulged in the wildest and most frenzied dancing, until they sank
+to the ground utterly exhausted and almost lifeless. The profuse
+perspiring resulting from these exertions was supposed to be the
+only efficacious remedy for the disease. Certain forms of music
+were regarded as of especial value in treating this tarantism, and
+hence the name of "tarantella" was applied to them. Our frontispiece,
+taken from Athanasius Kircher's <i>Magnes sive de Arte Magnetica</i>,
+1643 ed., represents the most commonly implicated spider and illustrates
+some of what Fabre has aptly designated as "medical
+choreography."</p>
+
+<p>The disease was, in reality, a form of hysteria, spreading by sympathy
+until whole communities were involved, and was paralleled by
+the outbreaks of the so-called St. Vitus's or St. John's dance, which<span class="pagenum"><a name="Page_9" id="Page_9">[Pg 9]</a></span>
+swept Germany at about the same time (<a href="#Fig_5">fig.&nbsp;5</a>). The evidence that
+the spider was the cause of the first is about as conclusive as is that
+of the demoniacal origin of the latter. The true explanation of the
+outbreaks is doubtless to be found in the depleted physical and mental
+condition of the people, resulting from the wars and the frightful
+plagues which devastated all Europe previous to, and during these
+times. An interesting discussion of these aspects of the question is to
+be found in Hecker.</p>
+
+<div class="figcenter" style="width: 300px;"><a name="Fig_5" id="Fig_5"></a>
+<a href="images/f005-full.png"><img src="images/f005.png" width="300" height="218" alt="5. Dancing mania. Illustration from Johann Ludwig Gottfried&#39;s Chronik. 1632." title="5. Dancing mania. Illustration from Johann Ludwig Gottfried&#39;s Chronik. 1632." /></a>
+<span class="caption">5. Dancing mania. Illustration from Johann Ludwig Gottfried&#39;s Chronik. 1632.</span>
+</div>
+
+<p>So gross has been the exaggeration and so baseless the popular fear
+regarding spiders that entomologists have been inclined to discredit
+all accounts of serious injury from their bites. Not only have the
+most circumstantial of newspaper accounts proved to be without
+foundation but there are on record a number of cases where the bite
+of many of the commoner species have been intentionally provoked
+and where the effect has been insignificant. Some years ago the
+senior author personally experimented with a number of the largest of
+our northern species, and with unexpected results. The first surprise
+was that the spiders were very unwilling to bite and that it required a
+considerable effort to get them to attempt to do so. In the second<span class="pagenum"><a name="Page_10" id="Page_10">[Pg 10]</a></span>
+place, most of those experimented with were unable to pierce the skin
+of the palm or the back of the hand, but had to be applied to the thin
+skin between the fingers before they were able to draw blood. Unfortunately,
+no special attempt was made to determine, at the time, the
+species experimented with, but among them were <i>Theridion tepidariorum</i>,
+<i>Miranda aurantia</i> (<i>Argiopa</i>), <i>Metargiope trifasciata</i>, <i>Marxia
+stellata</i>, <i>Aranea trifolium</i>, <i>Misumena vatia</i>, and <i>Agelena nævia</i>. In
+no case was the bite more severe than a pin prick and though in some
+cases the sensation seemed to last longer, it was probably due to the
+fact that the mind was intent upon the experiment.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_6" id="Fig_6"></a>
+<a href="images/f006-full.png"><img src="images/f006.png" width="400" height="171" alt="6. An American tarantula (Eurypelma hentzii). Natural size. After Comstock." title="6. An American tarantula (Eurypelma hentzii). Natural size. After Comstock." /></a>
+<span class="caption">6. An American tarantula (Eurypelma hentzii). Natural size. After Comstock.</span>
+</div>
+
+<p>Similar experiments were carried out by Blackwell (1855), who
+believed that in the case of insects bitten, death did not result any
+more promptly than it would have from a purely mechanical injury of
+equal extent. He was inclined to regard all accounts of serious
+injury to man as baseless. The question cannot be so summarily
+dismissed, and we shall now consider some of the groups which have
+been more explicitly implicated.</p>
+
+
+<p><a name="The_Tarantulas" id="The_Tarantulas"></a><b>The Tarantulas.</b>&mdash;In popular usage, the term "tarantula" is
+loosely applied to any one of a number of large spiders. The famous
+tarantulas of southern Europe, whose bites were supposed to cause the
+dancing mania, were Lycosidæ, or wolf-spiders. Though various
+species of this group were doubtless so designated, the one which
+seems to have been most implicated was <i>Lycosa tarantula</i> (L.),
+(<a href="#Fig_4">fig.&nbsp;4</a>). On the other hand, in this country, though there are many
+Lycosidæ, the term "tarantula" has been applied to members of the
+superfamily Avicularoidea (<a href="#Fig_6">fig.&nbsp;6</a>), including the bird-spiders.</p>
+
+<p>Of the Old World Lycosidæ there is no doubt that several species
+were implicated as the supposed cause of the tarantism. In fact, as
+we have already noted, the blame was sometimes attached to a scorpion.<span class="pagenum"><a name="Page_11" id="Page_11">[Pg 11]</a></span>
+However, there seems to be no doubt that most of the accounts
+refer to the spider known as <i>Lycosa tarantula</i>.</p>
+
+<p>There is no need to enter into further details here regarding the
+supposed virulence of these forms, popular and the older medical
+literature abound in circumstantial accounts of the terrible effects of
+the bite. Fortunately, there is direct experimental evidence which
+bears on the question.</p>
+
+<p>Fabre induced a common south European wolf-spider, <i>Lycosa
+narbonensis</i>, to bite the leg of a young sparrow, ready to leave the
+nest. The leg seemed paralyzed as a result of the bite, and though
+the bird seemed lively and clamored for food the next day, on the
+third day it died. A mole, bitten on the nose, succumbed after thirty-six
+hours. From these experiments Fabre seemed justified in his
+conclusion that the bite of this spider is not an accident which man
+can afford to treat lightly. Unfortunately, there is nothing in the
+experiments, or in the symptoms detailed, to exclude the probability
+that the death of the animals was the result of secondary infection.</p>
+
+<p>As far back as 1693, as we learn from the valuable account of
+Kobert, (1901), the Italian physician, Sanguinetti allowed himself to
+be bitten on the arm by two tarantulas, in the presence of witnesses.
+The sensation was equivalent to that from an ant or a mosquito bite
+and there were no other phenomena the first day. On the second day
+the wound was inflamed and there was slight ulceration. It is clear
+that these later symptoms were due to a secondary infection. These
+experiments have been repeated by various observers, among whom
+may be mentioned Leon Dufour, Josef Erker and Heinzel, and with
+the similar conclusion that the bite of the Italian tarantula ordinarily
+causes no severe symptoms. In this conclusion, Kobert, though
+firmly convinced of the poisonous nature of some spiders, coincides.
+He also believes that striking symptoms may be simulated or artificially
+induced by patients in order to attract interest, or because
+they have been assured that the bite, under all circumstances, caused
+tarantism.</p>
+
+<p>The so-called Russian tarantula, <i>Trochosa singoriensis</i> (<a href="#Fig_7">fig.&nbsp;7</a>), is
+much larger than the Italian species, and is much feared. Kobert
+carried out a series of careful experiments with this species and his
+results have such an important bearing on the question of the venomous
+nature of the tarantula that we quote his summary. Experimenting
+first on nearly a hundred living specimens of <i>Trochosa
+singoriensis</i> from Crimea he says that:<span class="pagenum"><a name="Page_12" id="Page_12">[Pg 12]</a></span></p>
+
+<p>"The tarantulas, no matter how often they were placed on the
+skin, handled, and irritated, could not be induced to bite either myself,
+the janitor, or the ordinary experimental animals. The objection
+that the tarantulas were weak and indifferent cannot stand, for as
+soon as I placed two of them on the shaved skin of a rabbit, instead of
+an attack on the animal, there began a furious battle between the
+two spiders, which did not cease until one of the two was killed."</p>
+
+<div class="figleft" style="width: 300px;"><a name="Fig_7" id="Fig_7"></a>
+<a href="images/f007-full.png"><img src="images/f007.png" width="300" height="373" alt="7. Trochosa singoriensis. After Kobert." title="7. Trochosa singoriensis. After Kobert." /></a>
+<span class="caption">7. Trochosa singoriensis. After Kobert.</span>
+</div>
+
+<p>"Since the spiders would not
+bite, I carefully ground up the
+fresh animals in physiological
+salt solution, preparing an extract
+which must have contained, in
+solution, all of the poisonous
+substance of their bodies. While
+in the case of <i>Latrodectus</i>, as we
+shall see, less than one specimen
+sufficed to yield an active extract,
+I have injected the filtered extract
+of six fresh Russian tarantulas,
+of which each one was much
+heavier than an average <i>Latrodectus</i>,
+subcutaneously and into
+the jugular vein of various cats
+without the animals dying or
+showing any special symptoms.
+On the basis of my experiments I can therefore only say that the
+quantity of the poison soluble in physiological salt solution, even
+when the spiders are perfectly fresh and well nourished, is very
+insignificant. That the poison of the Russian tarantula is not
+soluble in physiological salt solution, is exceedingly improbable.
+Moreover, I have prepared alcoholic extracts and was unable to
+find them active. Since the Russian spider exceeds the Italian in
+size and in intensity of the bite, it seems very improbable to me that
+the pharmacological test of the Italian tarantula would yield
+essentially other results than those from the Russian species."</p>
+
+<p>To the <a name="Avicularoidea" id="Avicularoidea"></a><b>Avicularoidea</b> belong the largest and most formidable
+appearing of the spiders and it is not strange that in the New World
+they have fallen heir to the bad reputation, as well as to the name of
+the tarantula of Europe. In this country they occur only in the
+South or in the far West, but occasionally living specimens are brought<span class="pagenum"><a name="Page_13" id="Page_13">[Pg 13]</a></span>
+to our northern ports in shipments of bananas and other tropical
+produce, and are the source of much alarm. It should be mentioned,
+however, that the large spider most frequently found under such circumstances
+is not a tarantula at all, but one of the Heteropodidæ, or
+giant crab-spiders, (<a href="#Fig_8">fig.&nbsp;8</a>).</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_8" id="Fig_8"></a>
+<a href="images/f008-full.png"><img src="images/f008.png" width="400" height="341" alt="8. The giant crab-spider or banana spider (Heteropoda venatoria).
+Natural size. After Comstock." title="8. The giant crab-spider or banana spider (Heteropoda venatoria).
+Natural size. After Comstock." /></a>
+<span class="caption">8. The giant crab-spider or banana spider (Heteropoda venatoria).
+Natural size. After Comstock.</span>
+</div>
+
+<p>In spite of their prominence and the fear which they arouse there
+are few accurate data regarding these American tarantulas. It has
+often been shown experimentally that they can kill small birds and
+mammals, though it is doubtful if these form the normal prey of any
+of the species, as has been claimed. There is no question but that
+the mere mechanical injury which they may inflict, and the consequent
+chances of secondary infection, justify, in part, their bad reputation.
+In addition to the injury from their bite, it is claimed that the body
+hairs of several of the South American species are readily detached
+and are urticating.</p>
+
+<p>Recently, Phisalix (1912) has made a study of the physiological
+effects of the venom of two Avicularoidea, <i>Phormictopus carcerides</i>
+Pocock, from Haiti and <i>Cteniza sauvagei</i> Rossi, from Corsica. The
+glands were removed aseptically and ground up with fine, sterilized
+sand in distilled water. The resultant liquid was somewhat viscid,
+colorless, and feebly alkaline. Injected into sparrows and mice the<span class="pagenum"><a name="Page_14" id="Page_14">[Pg 14]</a></span>
+extract of <i>Phormictopus</i> proved very actively poisonous, that from a
+single spider being sufficient to kill ten sparrows or twenty mice. It
+manifested itself first and, above all, as a narcotic, slightly lowering
+the temperature and paralyzing the respiration. Muscular and
+cardiac weakening, loss of general sensibility, and the disappearance
+of reflexes did not occur until near the end. The extract from <i>Cteniza</i>
+was less active and, curiously enough, the comparative effect on
+sparrows and on mice was just reversed.</p>
+
+
+<p><a name="Spiders_of_the_Genus_Latrodectus" id="Spiders_of_the_Genus_Latrodectus"></a><b>Spiders of the Genus Latrodectus.</b>&mdash;While most of the popular
+accounts of evil effects from the bites of spiders will not stand investigation,
+it is a significant fact that, the world over, the best authenticated
+records refer to a group of small and comparatively insignificant
+spiders belonging to the genus <i>Latrodectus</i>, of the family Theridiidæ.
+The dread "Malmigniatte" of Corsica and South Europe, the "Karakurte"
+of southeastern Russia, the "Katipo" of New Zealand, the
+"Mena-vodi" and "Vancoho" of Madagascar, and our own <i>Latrodectus
+mactans</i>, all belong to this genus, and concerning all of these the most
+circumstantial accounts of their venomous nature are given. These
+accounts are not mere fantastic stories by uneducated natives but in
+many cases are reports from thoroughly trained medical men.</p>
+
+<p>The symptoms produced are general, rather than local. As
+summarized by Kobert (1901) from a study of twenty-two cases
+treated in 1888, in the Kherson (Russia) Government Hospital and
+Berislaw (Kherson) District Hospital the typical case, aside from
+complications, exhibits the following symptoms. The victim suddenly
+feels the bite, like the sting of a bee. Swelling of the barely
+reddened spot seldom follows. The shooting pains, which quickly
+set in, are not manifested at the point of injury but localized at the
+joints of the lower limb and in the region of the hip. The severity
+of the pain forces the victim to the hospital, in spite of the fact that
+they otherwise have a great abhorrence of it. The patient is unable
+to reach the hospital afoot, or, at least, not without help, for there is
+usually inability to walk. The patient, even if he has ridden, reaches
+the hospital covered with cold sweat and continues to perspire for a
+considerable period. His expression indicates great suffering. The
+respiration may be somewhat dyspn&oelig;ic, and a feeling of oppression
+in the region of the heart is common. There is great aversion to
+solid food, but increasing thirst for milk and tea. Retention of
+urine, and constipation occur. Cathartics and, at night, strong<span class="pagenum"><a name="Page_15" id="Page_15">[Pg 15]</a></span>
+narcotics are desired. Warm baths give great relief. After three
+days, there is marked improvement and usually the patient is dismissed
+after the fifth. This summary of symptoms agrees well with
+other trustworthy records.</p>
+
+<p>It would seem, then, that Riley and Howard (1889), who discussed
+a number of accounts in the entomological literature, were fully
+justified in their statement that "It must be admitted that certain
+spiders of the genus <i>Latrodectus</i> have the power to inflict poisonous
+bites, which may (probably exceptionally and depending upon exceptional
+conditions) bring about the death of a human being."</p>
+
+<p>And yet, until recently the evidence bearing on the question has
+been most conflicting. The eminent arachnologist, Lucas, (1843)
+states that he himself, had been repeatedly bitten by the Malmigniatte
+without any bad effects. Dr. Marx, in 1890, gave before the Entomological
+Society of Washington, an account of a series of experiments
+to determine whether the bite of <i>Latrodectus mactans</i> is poisonous or
+not. He described the poison glands as remarkably small<a name="FNanchor_A_1" id="FNanchor_A_1"></a><a href="#Footnote_A_1" class="fnanchor">[A]</a> and stated
+that he had introduced the poison in various ways into guinea-pigs
+and rabbits without obtaining any satisfactory results. Obviously,
+carefully conducted experiments with the supposed venom were
+needed and fortunately they have been carried out in the greatest
+detail by Kobert (1901).</p>
+
+<p>This investigator pointed out that there were two factors which
+might account for the discrepancies in the earlier experiments. In
+the first place, the poison of spiders, as of snakes, might be so exhausted
+after two or three bites that further bites, following directly,
+might be without visible effect. Secondly, the application of the
+poison by means of the bite, is exceedingly inexact, since even after
+the most careful selection of the point of application, the poison might
+in one instance enter a little vein or lymph vessel, and in another case
+fail to do so. Besides, there would always remain an incalculable and
+very large amount externally, in the nonabsorptive epithelium.
+While all of these factors enter into the question of the effect of the
+bite in specific instances, they must be as nearly as possible obviated
+in considering the question of whether the spiders really secrete a
+venom harmful to man.</p>
+<p><span class="pagenum"><a name="Page_16" id="Page_16">[Pg 16]</a></span></p>
+<p>Kobert therefore sought to prepare extracts which would contain
+the active principles of the poison and which could be injected in
+definite quantities directly into the blood of the experimental animal.
+For this purpose various parts of the spiders were rubbed up in a mortar
+with distilled water, or physiological salt solution, allowed to
+stand for an hour, filtered, and then carefully washed, by adding water
+drop by drop for twenty-four hours. The filtrate and the wash-water
+were then united, well mixed and, if necessary, cleared by centrifuging
+or by exposure to cold. The mixture was again filtered,
+measured, and used, in part, for injection and, in part, for the determination
+of the organic materials.</p>
+
+<p>Such an extract was prepared from the cephalothoraces of eight
+dried specimens of the Russian <i>Latrodectus</i> and three cubic centimeters
+of this, containing 4.29 mg. of organic material, were injected into
+the jugular vein of a cat weighing 2450 grams. The previously very
+active animal was paralyzed and lay in whatever position it was
+placed. The sensibility of the skin of the extremities and the rump
+was so reduced that there was no reaction from cutting or sticking.
+There quickly followed dyspn&oelig;a, convulsions, paralysis of the
+respiratory muscles and of the heart. In twenty-eight minutes the
+cat was dead, after having exhibited exactly the symptoms observed
+in severe cases of poisoning of man from the bite of this spider.</p>
+
+<p>These experiments were continued on cats, dogs, guinea pigs and
+various other animals. Not only extracts from the cephalothorax,
+but from other parts of the body, from newly hatched spiders, and
+from the eggs were used and all showed a similar virulence. Every
+effort was made to avoid sources of error and the experiments, conducted
+by such a recognized authority in the field of toxicology, must
+be accepted as conclusively showing that this spider and, presumably,
+other species of the genus <i>Latrodectus</i> against which the clinical evidence
+is quite parallel, possess a poison which paralyzes the heart and
+central nervous system, with or without preliminary stimulus of the
+motor center. If the quantity of the poison which comes into direct
+contact with the blood is large, there may occur hæmolysis and
+thrombosis of the vessels.</p>
+
+<p>On the other hand, check experiments were carried out, using
+similar extracts of many common European spiders of the genera
+<i>Tegenaria</i>, <i>Drassus</i>, <i>Agelena</i>, <i>Eucharia</i> and <i>Argyroneta</i>, as well as
+the Russian tarantula, <i>Lycosa singoriensis</i>. In no other case was the
+effect on experimental animals comparable to the <i>Latrodectus</i> extract.<span class="pagenum"><a name="Page_17" id="Page_17">[Pg 17]</a></span></p>
+
+<p>Kobert concludes that in its chemical nature the poison is neither
+an alkaloid, nor a glycoside, nor an acid, but a toxalbumen, or poisonous
+enzyme which is very similar to certain other animal poisons,
+notably that of the scorpion.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_9" id="Fig_9"></a>
+<a href="images/f009-full.png"><img src="images/f009.png" width="350" height="396" alt="9. Latrodectus mactans; (a) female, x 3; (b) venter of female; (c) dorsum of male.
+After Comstock." title="9. Latrodectus mactans; (a) female, x 3; (b) venter of female; (c) dorsum of male.
+After Comstock." /></a>
+<span class="caption">9. Latrodectus mactans; (<i>a</i>)&nbsp;female, ×3; (<i>b</i>)&nbsp;venter of female; (<i>c</i>)&nbsp;dorsum of male.
+After Comstock.</span>
+</div>
+
+<p>The genus <i>Latrodectus</i> is represented in the United States by at
+least two species, <i>L. mactans</i> and <i>L. geometricus</i>. Concerning <i>L.
+mactans</i> there are very circumstantial accounts of serious injury and
+even death in man<a name="FNanchor_B_2" id="FNanchor_B_2"></a><a href="#Footnote_B_2" class="fnanchor">[B]</a>. <i>Latrodectus mactans</i> is coal black, marked with
+red or yellow or both. It has eight eyes, which are dissimilar in<span class="pagenum"><a name="Page_18" id="Page_18">[Pg 18]</a></span>
+color and are distinctly in front of the middle of the thorax, the
+lateral eyes of each side widely separate. The <span title="for tarsi read tarsus"><a name="AC_2" id="AC_2"></a>tarsi</span> of the fourth
+pair of legs has a number of curved setæ in a single series. It has on
+the ventral side of its abdomen an hour-glass shaped spot. The full-grown
+female is about half an inch in length. Its globose abdomen is
+usually marked with one or more red spots dorsally along the middle
+line. The male is about half as long but has in addition to the dorsal
+spots, four pairs of stripes along the sides. Immature females
+resemble the male in coloring (<a href="#Fig_9">fig.&nbsp;9</a>).</p>
+
+<p>Regarding the distribution of <i>Latrodectus mactans</i>, Comstock
+states that: "Although it is essentially a Southern species, it occurs
+in Indiana, Ohio, Pennsylvania, New Hampshire, and doubtless other
+of the Northern States." <i>L. geometricus</i> has been reported from
+California.</p>
+
+
+<p><a name="Other_Venomous_Spiders" id="Other_Venomous_Spiders"></a><b>Other Venomous Spiders</b>&mdash;While conclusive evidence regarding
+the venomous nature of spiders is meager and relates almost wholly
+to that of the genus <i>Latrodectus</i>, the group is a large one and we are
+not justified in dismissing arbitrarily, all accounts of injury from their
+bites. Several species stand out as especially needing more detailed
+investigation.</p>
+
+<p><i>Chiracanthium nutrix</i> is a common European species of the family
+Clubionidæ, concerning which there is much conflicting testimony.
+Among the reports are two by distinguished scientists whose accounts
+of personal experiences cannot be ignored. A. Forel allowed a spider
+of this species to bite him and not only was the pain extreme, but the
+general symptoms were so severe that he had to be helped to his
+house. The distinguished arachnologist, Bertkau reports that he,
+himself, was bitten and that an extreme, burning pain spread almost
+instantaneously over the arm and into the breast. There were slight
+chills the same day and throbbing pain at the wound lasted for days.
+While this particular species is not found in the United States, there
+are two other representatives of the genus and it is possible that they
+possess the same properties. We are unaware of any direct experimental
+work on the poison.</p>
+
+<p><i>Epeira diadema</i>, of Europe, belongs to a wholly different group,
+that of the orb-weavers, but has long been reputed venomous. Kobert
+was able to prepare from it an extract whose effects were very similar
+to that prepared from <i>Latrodectus</i>, though feebler in its action. Under
+ordinary circumstances this spider is unable to pierce the skin of man<span class="pagenum"><a name="Page_19" id="Page_19">[Pg 19]</a></span>
+and though Kobert's results seem conclusive, the spider is little to
+be feared.</p>
+
+<p><i>Phidippus audax</i> (<i>P. tripunctatus</i>) is one of our largest Attids,
+or jumping spiders. The late Dr. O. Lugger describes a case of severe
+poisoning from the bite of this spider and though details are lacking,
+it is quite possible that this and other large species of the same group,
+which stalk their prey, may possess a more active poison than that of
+web-building species.</p>
+
+
+<p><a name="Summary" id="Summary"></a><b>Summary</b>&mdash;It is clearly established that our common spiders are
+not to be feared and that the stories regarding their virulence are
+almost wholly without foundation.
+On the other hand, the
+chances of secondary infection
+from the bites of some of the
+more powerful species are not
+to be ignored.</p>
+
+<p>Probably all species possess
+a toxin secreted by the poison
+gland, virulent for insects and
+other normal prey of the
+spiders, but with little or no
+effect on man.</p>
+
+<p>There are a very few species,
+notably of the genus <i>Latrodectus</i>,
+and possibly including the European
+<i>Chiracanthium nutrix</i> and
+<i>Epeira diadema</i>, which possess,
+in addition, a toxalbumen
+derived from the general body
+tissue, which is of great virulence
+and may even cause death in man and the higher animals.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_10" id="Fig_10"></a>
+<a href="images/f010-full.png"><img src="images/f010.png" width="350" height="482" alt="10. A whip-scorpion (Mastigoproctus giganteus).
+Half natural size. After Comstock." title="10. A whip-scorpion (Mastigoproctus giganteus).
+Half natural size. After Comstock." /></a>
+<span class="caption">10. A whip-scorpion (Mastigoproctus giganteus).
+Half natural size. After Comstock.</span>
+</div>
+
+
+<h3><a name="THE_PEDIPALPIDA_OR_WHIP-SCORPIONS" id="THE_PEDIPALPIDA_OR_WHIP-SCORPIONS"></a>THE PEDIPALPIDA OR WHIP-SCORPIONS</h3>
+
+<p>The tailed whip-scorpions, belonging to the family Thelyphonidæ,
+are represented in the United States by the giant whip-scorpion
+<i>Mastigoproctus giganteus</i> (<a href="#Fig_10">fig.&nbsp;10</a>), which is common in Florida, Texas
+and some other parts of the South. In Florida, it is locally known as
+the "grampus" or "mule-killer" and is very greatly feared. There is
+no evidence that these fears have any foundation, and Dr. Marx
+states that there is neither a poison gland nor a pore in the claw of the
+chelicera.<span class="pagenum"><a name="Page_20" id="Page_20">[Pg 20]</a></span></p>
+
+
+<h3><a name="THE_SCORPIONIDA_OR_TRUE_SCORPIONS" id="THE_SCORPIONIDA_OR_TRUE_SCORPIONS"></a>THE SCORPIONIDA, OR TRUE SCORPIONS</h3>
+
+<p>The true scorpions are widely distributed throughout warm countries
+and everywhere bear an evil reputation. According to Comstock
+(1912), about a score of species occur in the Southern United States.
+These are comparatively small forms but in the tropics members of
+this group may reach a length of seven or eight inches. They are
+pre-eminently predaceous forms, which lie hidden during the day and
+seek their prey by night.</p>
+
+<div class="figleft" style="width: 300px;"><a name="Fig_11" id="Fig_11"></a>
+<a href="images/f011-full.png"><img src="images/f011.png" width="300" height="591" alt="11. A true scorpion. After
+Comstock." title="11. A true scorpion. After
+Comstock." /></a>
+<span class="caption">11. A true scorpion. After
+Comstock.</span>
+</div>
+
+<p>The scorpions (<a href="#Fig_11">fig.&nbsp;11</a>) possess large pedipalpi, terminated by
+strongly developed claws, or chelæ. They may be distinguished from
+all other Arachnids by the fact that the distinctly
+segmented abdomen is divided into a
+broad basal region of seven segments and a
+terminal, slender, tail-like division of five
+distinct segments.</p>
+
+<p>The last segment of the abdomen, or
+telson, terminates in a ventrally-directed,
+sharp spine, and contains a pair of highly
+developed poison glands. These glands open
+by two small pores near the tip of the spine.
+Most of the species when running carry the
+tip of the abdomen bent upward over the
+back, and the prey, caught and held by the
+pedipalpi, is stung by inserting the spine of
+the telson and allowing it to remain for a
+time in the wound.</p>
+
+<p>The glands themselves have been studied
+in <i>Prionurus citrinus</i> by Wilson (1904).
+He found that each gland is covered by a sheet of muscle on its
+mesal and dorsal aspects, which may be described as the <i>compressor
+muscle</i>. The muscle of each side is inserted by its edge along the
+ventral inner surface of the chitinous wall of the telson, close to the
+middle line, and by a broader insertion laterally. A layer of fine
+connective tissue completely envelops each gland and forms the
+basis upon which the secreting cells rest. The secreting epithelium
+is columnar; and apparently of three different types of cells.</p>
+
+<p>1. The most numerous have the appearance of mucous cells,
+resembling the goblet cells of columnar mucous membranes. The
+nucleus, surrounded by a small quantity of protoplasm staining with
+hæmatoxylin, lies close to the base of the cell.<span class="pagenum"><a name="Page_21" id="Page_21">[Pg 21]</a></span></p>
+
+<p>2. Cells present in considerable numbers, the peripheral portions
+of which are filled with very numerous fine granules, staining
+with acid dyes such as methyl orange.</p>
+
+<p>3. Cells few in number, filled with very large granules, or irregular
+masses of a substance staining with hæmatoxylin.</p>
+
+<p>The poison, according to Kobert (1893), is a limpid, acid-reacting
+fluid, soluble in water but insoluble in absolute alcohol and ether.
+There are few data relative to its chemical nature. Wilson (1901)
+states that a common Egyptian species, <i>Buthus quinquestriatus</i>, has
+a specific gravity of 1.092, and contains 20.3% of solids and 8.4% ash.</p>
+
+<p>The venom of different species appears to differ not only quantitatively
+but qualitatively. The effects of the bite of the smaller species
+of the Southern United States may be painful but there is no satisfactory
+evidence that it is ever fatal. On the other hand, certain
+tropical species are exceedingly virulent and cases of death of man
+from the bite are common.</p>
+
+<p>In the case of <i>Buthus quinquestriatus</i>, Wilson (1904) found the
+symptoms in animals to be hypersecretion, salivation and lachrymation,
+especially marked, convulsions followed by prolonged muscular
+spasm; death from asphyxia. The temperature shows a
+slight, rarely considerable, rise. Rapid and considerable increase
+of blood-pressure (observed in dogs) is followed by a gradual fall with
+slowing of the heart-beat. The coagulability of the blood is not
+affected.</p>
+
+<p>An interesting phase of Wilson's work was the experiments on
+desert mammals. The condition under which these animals exist
+must frequently bring them in contact with scorpions, and he found
+that they possess a degree of immunity to the venom sufficient at
+least to protect them from the fatal effects of the sting.</p>
+
+<p>As far as concerns its effect on man, Wilson found that much
+depended upon the age. As high as 60 per cent of the cases of
+children under five, resulted fatally. Caroroz (1865), states that in a
+Mexican state of 15,000 inhabitants, the scorpions were so abundant
+and so much feared that the authorities offered a bounty for their
+destruction. A result was a large number of fatalities, over two
+hundred per year. Most of the victims were children who had
+attempted to collect the scorpions.</p>
+
+<p>The treatment usually employed in the case of bites by the more
+poisonous forms is similar to that for the bite of venomous snakes.
+First, a tight ligature is applied above the wound so as to stop the<span class="pagenum"><a name="Page_22" id="Page_22">[Pg 22]</a></span>
+flow of blood and lymph from that region. The wound is then
+freely excised and treated with a strong solution of permanganate
+of potash, or with lead and opium lotion.</p>
+
+<p>In recent years there have been many attempts to prepare an
+antivenom, or antiserum comparable to what has been used so
+effectively in the case of snake bites. The most promising of these
+is that of Todd (1909), produced by the immunization of suitable
+animals. This antivenom proved capable of neutralizing the venom
+when mixed <i>in vitro</i> and also acts both prophylactically and curatively
+in animals. Employed curatively in man, it appears to have
+a very marked effect on the intense pain following the sting, and
+the evidence so far indicates that its prompt use greatly reduces
+the chance of fatal results.</p>
+
+
+<h3><a name="THE_SOLPUGIDA_OR_SOLPUGIDS" id="THE_SOLPUGIDA_OR_SOLPUGIDS"></a>THE SOLPUGIDA, OR SOLPUGIDS</h3>
+
+<p>The <b>Solpugida</b> are peculiar spider-like forms which are distinguished
+from nearly all other
+arachnids by the fact that
+they possess no true cephalothorax,
+the last two leg-bearing
+segments being distinct,
+resembling those of the abdomen
+in this respect. The
+first pair of legs is not used
+in locomotion but seemingly
+functions as a second pair of
+pedipalpi. <a href="#Fig_12">Figure 12</a> illustrates
+the striking peculiarities
+of the group. They are
+primarily desert forms and
+occur in the warm zones of
+all countries. Of the two
+hundred or more species,
+Comstock lists twelve as
+occurring in our fauna.
+These occur primarily in the
+southwest.</p>
+
+<div class="figleft" style="width: 300px;"><a name="Fig_12" id="Fig_12"></a>
+<a href="images/f012-full.png"><img src="images/f012.png" width="300" height="424" alt="12. A solpugid (Eremobates cinerea). After Comstock." title="12. A solpugid (Eremobates cinerea). After Comstock." /></a>
+<span class="caption">12. A solpugid (Eremobates cinerea). After Comstock.</span>
+</div>
+
+<p>The Solpugida have long
+borne a bad reputation and, regarding virulence, have been classed
+with the scorpions. Among the effects of their bites have been<span class="pagenum"><a name="Page_23" id="Page_23">[Pg 23]</a></span>
+described painful swelling, gangrene, loss of speech, cramps, delirium,
+unconsciousness and even death. Opposed to the numerous loose
+accounts of poisoning, there are a number of careful records by
+physicians and zoölogists which indicate clearly that the effects are
+local and though they may be severe, they show not the slightest
+symptom of direct poisoning.</p>
+
+<p>More important in the consideration of the question is the fact
+that there are neither poison glands nor pores in the fangs for the
+exit of any poisonous secretion. This is the testimony of a number
+of prominent zoölogists, among whom is Dr. A.&nbsp;Walter, who wrote
+to Kobert at length on the subject and whose conclusions are presented
+by him.</p>
+
+<p>However, it should be noted that the fangs are very powerful
+and are used in such a manner that they may inflict especially severe
+wounds. Thus, there may be more opportunity for secondary
+infection than is usual in the case of insect wounds.</p>
+
+<p>The treatment of the bite of the Solpugida is, therefore, a matter
+of preventing infection. The wound should be allowed to bleed
+freely and then washed out with a 1:3000 solution of corrosive
+sublimate, and, if severe, a wet dressing of this should be applied.
+If infection takes place, it should be treated in the usual manner,
+regardless of its origin.</p>
+
+
+<h3><a name="THE_ACARINA_OR_MITES_AND_TICKS" id="THE_ACARINA_OR_MITES_AND_TICKS"></a>THE ACARINA, OR MITES AND TICKS</h3>
+
+<p>A number of the parasitic Acarina evidently secrete a
+specific poison, presumably carried by the saliva, but in most cases
+its effect on man is insignificant. There is an abundant literature
+dealing with the poisonous effect of the bite of these forms, especially
+the ticks, but until recently it has been confused by failure to recognize
+that various species may transmit diseases of man, rather than
+produce injury through direct poisoning. We shall therefore
+discuss the Acarina more especially in subsequent chapters, dealing
+with parasitism and with disease transmission.</p>
+
+<p>Nevertheless, after the evidence is sifted, there can be no doubt
+that the bites of certain ticks may occasionally be followed by a
+direct poisoning, which may be either local or general in its effects.
+Nuttall (1908) was unable to determine the cause of the toxic effect,
+for, in <i>Argas persicus</i>, the species most often implicated, he failed to
+get the slightest local or general effect on experimental animals, from
+the injection of an emulsion prepared by crushing three of the ticks.<span class="pagenum"><a name="Page_24" id="Page_24">[Pg 24]</a></span></p>
+
+<p>It seems clearly established that the bite of certain ticks may
+cause a temporary paralysis, or even complete paralysis, involving
+the organs of respiration or the heart, and causing death. In 1912,
+Dr. I. U. Temple, of Pendleton, Oregon, reported several cases of
+what he called "acute ascending paralysis" associated with the occurrence
+of ticks on the head or the back of the neck. A typical severe
+case was that of a six year old child, who had retired in her usual
+normal health. The following morning upon arising she was unable
+to stand on her feet. She exhibited paralysis extending to the knees,
+slight temperature, no pain, sensory nerves normal, motor nerves
+completely paralyzed, reflexes absent. The following day the paralysis
+had extended to the upper limbs, and before night of the third
+day the nerves of the throat (hypoglossal) were affected. The thorax
+and larynx were involved, breathing was labored, she was unable
+to swallow liquids, phonation was impossible and she could only make
+low, guttural sounds. At this stage, two ticks, fully distended with
+blood, were found over the junction of the spinal column with the
+occipital bones in the hollow depression. They were removed by
+the application of undiluted creoline. Though the child's life was
+despaired of, by the following morning she was very much improved.
+By evening she was able to speak. The paralysis gradually receded,
+remaining longest in the feet, and at the end of one week the patient
+was able to go home.</p>
+
+<p>There was some doubt as to the exact species of tick implicated
+in the cases which Dr. Temple reported, although the evidence
+pointed strongly to <i>Dermacentor venustus</i>.<a name="FNanchor_C_3" id="FNanchor_C_3"></a><a href="#Footnote_C_3" class="fnanchor">[C]</a> Somewhat later, Hadwen
+(1913) reported that "tick paralysis" occurs in British Columbia,
+where it affects not only man, but sheep and probably other animals.
+It is caused by the bites of <i>Dermacentor venustus</i> and was experimentally
+produced in lambs and a dog (Hadwen and Nuttall, 1913).
+It is only when the tick begins to engorge or feed rapidly, some days
+after it has become attached, that its saliva produces pathogenic
+effects.</p>
+
+<p>Ulceration following tick bite is not uncommon. In many of the
+instances it is due to the file-like hypostome, with its recurved teeth,
+being left in the wound when the tick is forcibly pulled off.</p>
+<p><span class="pagenum"><a name="Page_25" id="Page_25">[Pg 25]</a></span></p>
+
+
+<h3><a name="THE_MYRIAPODA_OR_CENTIPEDES_AND_MILLIPEDES" id="THE_MYRIAPODA_OR_CENTIPEDES_AND_MILLIPEDES"></a>THE MYRIAPODA, OR CENTIPEDES AND MILLIPEDES</h3>
+
+<p>The old class, Myriapoda includes the <b>Diplopoda</b>, or
+millipedes, and the <b>Chilopoda</b>, or centipedes. The present
+tendency is to raise these groups to the rank of
+classes.</p>
+
+
+<h3>The Diplopoda</h3>
+
+<div class="figleft" style="width: 125px;"><a name="Fig_13" id="Fig_13"></a>
+<a href="images/f013-full.png"><img src="images/f013.png" width="125" height="527" alt="13. A millipede.
+After Comstock." title="13. A millipede.
+After Comstock." /></a>
+<span class="caption">13. A millipede.
+After Comstock.</span>
+</div>
+
+<p>The <b>Diplopoda</b>, or millipedes (<a href="#Fig_13">fig.&nbsp;13</a>), are characterized
+by the presence of two pairs of legs to a segment.
+The largest of our local myriapods belong to this group.
+They live in moist places, feeding primarily on decaying
+vegetable matter, though a few species occasionally
+attack growing plants.</p>
+
+<p>The millipedes are inoffensive and harmless. <i>Julus
+terrestris</i>, and related species, when irritated pour out
+over the entire body a yellowish secretion which escapes
+from cutaneous glands. It is
+volatile, with a pungent odor,
+and Phisalix (1900) has shown
+that it is an active poison when
+injected into the blood of experimental
+animals. This, however,
+does not entitle
+them to be considered
+as poisonous arthropods,
+in the sense of this
+chapter, any more than
+the toad can be considered
+poisonous to
+man because it secretes
+a venom from its cutaneous
+glands.</p>
+
+
+<h3>The Chilopoda</h3>
+
+<div class="figright" style="width: 323px;"><a name="Fig_14" id="Fig_14"></a>
+<a href="images/f014-full.png"><img src="images/f014.png" width="323" height="456" alt="14. Two common centipedes.
+
+(a) Lithobius forficatus.
+After Comstock.
+
+(b) Scutigera forceps. Natural
+size; after Howard." title="14. Two common centipedes.
+
+(a) Lithobius forficatus.
+After Comstock.
+
+(b) Scutigera forceps. Natural
+size; after Howard." /></a>
+<span class="caption">14. Two common centipedes.
+
+(<i>a</i>)&nbsp;Lithobius forficatus.
+After Comstock.
+
+(<i>b</i>)&nbsp;Scutigera forceps. Natural
+size; after Howard.</span>
+</div>
+
+<p>The <b>Chilopoda</b>, or
+centipedes (<a href="#Fig_14">fig.&nbsp;14</a>), unlike
+the millipedes, are
+predaceous forms, and
+possess well developed
+poison glands for killing
+their prey. These<span class="pagenum"><a name="Page_26" id="Page_26">[Pg 26]</a></span>
+glands are at the base of the first pair of legs (<a href="#Fig_15">fig.&nbsp;15</a>), which are
+bent forward so as to be used in holding their prey. The legs
+terminate in a powerful claw, at the tip of which is the
+outlet of the poison glands.</p>
+
+<p>The poison is a limpid, homogeneous, slightly acid
+fluid, which precipitates in distilled water. Briot (1904)
+extracted it from the glands of <i>Scolopendra morsitans</i>, a
+species common in central France, and found that it was
+actively venomous for the ordinary experimental animals.
+A rabbit of two kilograms weight received an
+injection of three cubic centimeters in the vein of the ear
+and died in a minute. A white rat, weighing forty-eight
+grams, received one and a half cubic centimeters in the
+hind leg. There was an almost immediate paralysis of
+the leg and marked necrosis of the tissues.</p>
+
+<div class="figleft" style="width: 200px;"><a name="Fig_15" id="Fig_15"></a>
+<a href="images/f015-full.png"><img src="images/f015.png" width="200" height="367" alt="15. Mandible of
+Scolopendra
+cingulata
+showing
+venom
+gland. After
+Dubosq." title="15. Mandible of
+Scolopendra
+cingulata
+showing
+venom
+gland. After
+Dubosq." /></a>
+<span class="caption">15. Mandible of
+Scolopendra
+cingulata
+showing
+venom
+gland. After
+Dubosq.</span>
+</div>
+
+<p>As for the effect on man, there is little foundation for the fear
+with which centipedes are regarded. Our native species produce,
+at most, local symptoms,&mdash;sometimes severe local pain and swelling,&mdash;but
+there is no authentic record of fatal results. In the tropics,
+some of the species attain a large size, <i>Scolopendra gigantea</i> reaching
+a length of nearly a foot. These forms are justly feared, and there
+is good evidence that death sometimes, though rarely, results from
+their bite.</p>
+
+<p>One of the most careful accounts of death from the sting of the
+scorpion is that of Linnell, (1914), which relates to a comparatively
+small Malayan species, unfortunately undetermined. The patient,
+a coolie, aged twenty, was admitted to a hospital after having been
+stung two days previously on the left heel. For cure, the other
+coolies had made him eat the head of the scorpion. On admission,
+the patient complained of "things creeping all over the body".
+Temp. 102.8°. On the fourth day he had paralysis of the legs, and
+on the fifth day motor paralysis to the umbilicus, sensation being
+unaltered. On the sixth day there was retention of the urine and
+on the ninth day (first test after third day) sugar was present. On
+the thirteenth day the patient became comatose, but could be
+roused to eat and drink. The temperature on the following day fell
+below 95° and the patient was still comatose. Death fifteenth day.</p>
+
+<p>Examination of the spinal (lumbar) cord showed acute disseminated
+myelitis. In one part there was an acute destruction of the
+anterior horn and an infiltration of round cells. In another portion<span class="pagenum"><a name="Page_27" id="Page_27">[Pg 27]</a></span>
+Clarke's column had been destroyed. The perivascular sheaths
+were crowded with small round cells and the meninges were congested.
+Some of the cells of the anterior horn were swollen and the
+nuclei eccentric; chromatolysis had occurred in many of them.</p>
+
+<p>As for treatment, Castellani and Chalmers (1910), recommend
+bathing the part well with a solution of ammonia (one in five, or one
+in ten). After bathing, apply a dressing of the same alkali or, if
+there is much swelling and redness, an ice-bag. If necessary, hypodermic
+injections of morphine may be given to relieve the pain.
+At a later period fomentations may be required to reduce the local
+inflammation.</p>
+
+
+<h3><a name="THE_HEXAPODA_OR_TRUE_INSECTS" id="THE_HEXAPODA_OR_TRUE_INSECTS"></a>THE HEXAPODA OR TRUE INSECTS</h3>
+
+<p>There are a number of <b>Hexapoda</b>, or true insects, which are, in
+one way or another, poisonous to man. These belong primarily
+to the orders Hemiptera, or true bugs; Lepidoptera, or butterflies
+and moths (larval forms); Diptera, or flies; Coleoptera, or beetles;
+and Hymenoptera, or ants, bees, and wasps. There are various ways
+in which they may be poisonous.</p>
+
+<p>1. <i>Piercing</i> or <i>biting</i> forms may inject an irritating or poisonous
+saliva into the wound caused by their mouth-parts.</p>
+
+<p>2. <i>Stinging forms</i> may inject a poison, from glands at the caudal
+end of the abdomen, into wounds produced by a specially modified
+ovipositer, the <i>sting</i>.</p>
+
+<p>3. <i>Nettling</i> properties may be possessed by the hairs of the insect.</p>
+
+<p>4. <i>Vescicating</i>, or <i>poisonous blood plasma</i>, or <i>body fluids</i> are
+known to exist in a large number of species and may, under exceptional
+circumstances, affect man.</p>
+
+<p>For convenience of discussion, we shall consider poisonous insects
+under these various headings. In this, as in the preceding discussion,
+no attempt will be made to give an exhaustive list of the poisonous
+forms. Typical instances will be selected and these will be chosen
+largely from North American species.</p>
+
+
+<h3><a name="PIERCING_OR_BITING_INSECTS_POISONOUS_TO_MAN" id="PIERCING_OR_BITING_INSECTS_POISONOUS_TO_MAN"></a>PIERCING OR BITING INSECTS POISONOUS TO MAN</h3>
+
+
+<h3><span class="smcap"><a name="Hemiptera" id="Hemiptera"></a>Hemiptera</span></h3>
+
+<p>Several families of the true bugs include forms which, while
+normally inoffensive, are capable of inflicting painful wounds on man.
+In these, as in all of the Hemiptera, the mouth-parts are modified<span class="pagenum"><a name="Page_28" id="Page_28">[Pg 28]</a></span>
+to form an organ for piercing and
+sucking. This is well shown by the
+accompanying illustration (<a href="#Fig_16">fig.&nbsp;16</a>).</p>
+
+<p>The upper lip, or <i>labrum</i>, is much
+reduced and immovable, the lower
+lip, or <i>labium</i>, is elongated to form
+a jointed sheath, within which the
+lance-like mandibles and maxillæ
+are enclosed. The mandibles are
+more or less deeply serrate, depending
+on the species concerned.</p>
+
+<div class="figleft" style="width: 400px;"><a name="Fig_16" id="Fig_16"></a>
+<a href="images/f016-full.png"><img src="images/f016.png" width="400" height="339" alt="16. Beak of hemipteron." title="16. Beak of hemipteron." /></a>
+<span class="caption">16. Beak of hemipteron.</span>
+</div>
+
+<p>The poison is elaborated by the salivary glands, excepting, possibly,
+in <i>Belostoma</i> where Locy is inclined to believe that it is secreted
+by the maxillary glands. The salivary glands
+of the Hemiptera have been the subject of
+much study but the most recent, comprehensive
+work has been done by Bugnion and Popoff,
+(1908 and 1910) to whose text the reader is
+referred for details.</p>
+
+<p>The Hemiptera have two
+pairs of salivary glands: the
+<i>primary gland</i>, of which the
+efferent duct leads to the
+salivary syringe, and the
+<i>accessory gland</i>, of which the
+very long and flexuous duct
+empties into the primary duct
+at its point of insertion.
+Thus, when one observes the
+isolated primary gland it appears as though it
+had efferent ducts inserted at the same point. In
+<i>Nepa</i> and the <i>Fulgoridæ</i> there are two accessory
+glands and therefore apparently three ducts
+at the same point on the primary gland. The
+<i>ensemble</i> differs greatly in appearance in different
+species but we shall show here Bugnion and
+Popoff's figure of the apparatus of <i>Notonecta
+maculata</i>, a species capable of inflicting a painful
+bite on man (<a href="#Fig_17">fig.&nbsp;17</a>).</p>
+
+<div class="figcenter" style="width: 200px;"><a name="Fig_17" id="Fig_17"></a>
+<a href="images/f017-full.png"><img src="images/f017.png" width="200" height="361" alt="17. Salivary glands of
+Notonecta maculata.
+After Bugnion and
+Popoff." title="17. Salivary glands of
+Notonecta maculata.
+After Bugnion and
+Popoff." /></a>
+<span class="caption">17. Salivary glands of
+Notonecta maculata.
+After Bugnion and
+Popoff.</span>
+</div>
+
+<div class="figcenter" style="width: 200px;"><a name="Fig_18" id="Fig_18"></a>
+<a href="images/f018-full.png"><img src="images/f018.png" width="200" height="524" alt="18. Pharyngeal syringe or
+salivary pump of Fulgora
+maculata. After
+Bugnion and Popoff." title="18. Pharyngeal syringe or
+salivary pump of Fulgora
+maculata. After
+Bugnion and Popoff." /></a>
+<span class="caption">18. Pharyngeal syringe or
+salivary pump of Fulgora
+maculata. After
+Bugnion and Popoff.</span>
+</div><p><span class="pagenum"><a name="Page_29" id="Page_29">[Pg 29]</a></span></p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_19" id="Fig_19"></a>
+<a href="images/f019-full.png"><img src="images/f019.png" width="400" height="515" alt="19. Heteroptera, (a) Melanolestes picipes; (b) Notonecta undulata; (c, d) Aradus robustus
+(c) adult, (d) nymph, much enlarged; (e) Arilus cristatus; (f) Belostoma americana;
+(g) Nabis (Coriscus) subcoleoptratus, enlarged; (h) Cimex lectularius, (i) Oeciacus
+vicarius, much enlarged; (j) Lyctocoris fitchii, much enlarged. After Lugger." title="19. Heteroptera, (a) Melanolestes picipes; (b) Notonecta undulata; (c, d) Aradus robustus
+(c) adult, (d) nymph, much enlarged; (e) Arilus cristatus; (f) Belostoma americana;
+(g) Nabis (Coriscus) subcoleoptratus, enlarged; (h) Cimex lectularius, (i) Oeciacus
+vicarius, much enlarged; (j) Lyctocoris fitchii, much enlarged. After Lugger." /></a>
+<span class="caption">19. Heteroptera, (<i>a</i>)&nbsp;Melanolestes picipes; (<i>b</i>)&nbsp;Notonecta undulata; (<i>c</i>,&nbsp;<i>d</i>)&nbsp;Aradus robustus
+(<i>c</i>)&nbsp;adult, (<i>d</i>)&nbsp;nymph, much enlarged; (<i>e</i>)&nbsp;Arilus cristatus; (<i>f</i>)&nbsp;Belostoma americana;
+(<i>g</i>)&nbsp;Nabis (Coriscus) subcoleoptratus, enlarged; (<i>h</i>)&nbsp;Cimex lectularius, (<i>i</i>)&nbsp;Oeciacus
+vicarius, much enlarged; (<i>j</i>)&nbsp;Lyctocoris fitchii, much enlarged. After Lugger.</span>
+</div>
+
+<p>Accessory to the salivary apparatus there is on the ventral side
+of the head, underneath the pharynx, a peculiar organ which the
+Germans have called the "Wanzenspritze," or syringe. The accompanying
+figure of the structure in <i>Fulgora maculata</i> (<a href="#Fig_18">fig.&nbsp;18</a>) shows
+its relation to the ducts of the salivary glands and to the beak. It is<span class="pagenum"><a name="Page_30" id="Page_30">[Pg 30]</a></span>
+made up of a dilatation forming the body of the pump, in which there
+is a chitinous piston. Attached to the piston is a strong retractor
+muscle. The function of the salivary pump is to suck up the saliva
+from the salivary ducts and to force it out through the beak.</p>
+
+<p>Of the Hemiptera reported as attacking man, we shall consider
+briefly the forms most frequently noted.</p>
+
+
+<p><a name="The_Notonectidae_or_back_swimmers" id="The_Notonectidae_or_back_swimmers"></a>The <b>Notonectidæ</b>, or <i>back swimmers</i>, (<a href="#Fig_19">fig.&nbsp;19<i>b</i></a>) are small, aquatic
+bugs that differ from all others in that they always swim on their
+backs. They are predaceous; feeding on insects and other small
+forms. When handled carelessly they are able to inflict a painful
+bite, which is sometimes as severe as the sting of a bee. In fact,
+they are known in Germany as "Wasserbienen."</p>
+
+
+<p><a name="The_Belostomatidae_or_giant_water_bugs" id="The_Belostomatidae_or_giant_water_bugs"></a>The <b>Belostomatidæ</b>, or <i>giant water bugs</i>, (<a href="#Fig_19">fig.&nbsp;19<i>f</i></a>) include the largest
+living Hemiptera. They are attracted to lights and on account of the
+large numbers which swarm about the electric street lamps in some
+localities they have received the popular name "electric light bugs."
+Our largest representatives in the northern United States belong to
+the two genera <i>Belostoma</i> and <i>Banacus</i>, distinguished from each
+other by the fact that <i>Belostoma</i> has a groove on the under side of
+the femur of the front leg, for the reception of the tibia.</p>
+
+<p>The salivary glands of Belostoma were figured by Leidy (1847)
+and later were studied in more detail by Locy (1884). There are
+two pairs of the glands, those of one pair being long and extending
+back as far as the beginning of the abdomen, while the others are
+about one-fourth as long. They lie on either side of the &oelig;sophagus.
+On each side of the &oelig;sophagus there is a slender tube with a
+sigmoid swelling which may serve as a poison reservoir. In addition
+to this salivary system, there is a pair of very prominent glands
+on the ventral side of the head, opening just above the base of the
+beak. These Locy has called the "cephalic glands" and he suggests
+that they are the source of the poison. They are the homologues
+of the maxillary glands described for other Hemiptera, and it is by
+no means clear that they are concerned with the production of
+venom. It seems more probable that in <i>Belostoma</i>, as in other
+Hemiptera, it is produced by the salivary glands, though the question
+is an open one.</p>
+
+<p>The Belostomatidæ feed not only on insects, but on small frogs,
+fish, salamanders and the like. Matheson (1907) has recorded the
+killing of a good-sized bird by <i>Belostoma americana</i>. A woodpecker,<span class="pagenum"><a name="Page_31" id="Page_31">[Pg 31]</a></span>
+or flicker, was heard to utter cries of distress,
+and fluttered and fell from a tree. On examination
+it was found that a bug of this species
+had inserted its beak into the back part of
+the skull and was apparently busily engaged
+in sucking the blood or brains of the bird.
+Various species of <i>Belostoma</i> have been cited
+as causing painful bites in man. We can
+testify from personal experience that the bite
+of <i>Belostoma americana</i> may almost immediately cause severe,
+shooting pains that
+may extend throughout
+the arm and that
+they may be felt for several days.</p>
+
+<div class="figleft" style="width: 300px;"><a name="Fig_20" id="Fig_20"></a>
+<a href="images/f020-full.png"><img src="images/f020.png" width="300" height="437" alt="20. Reduvius (Opsic&oelig;tus)
+personatus. (×2)." title="20. Reduvius (Opsic&oelig;tus)
+personatus. (×2)." /></a>
+<span class="caption">20. Reduvius (Opsic&oelig;tus)
+personatus. (×2).</span>
+</div>
+
+<p>Relief from the pain may be obtained by
+the use of dilute ammonia, or a menthol
+ointment. In the not uncommon case of
+secondary infection the usual treatment for
+that should be adopted.</p>
+
+<div class="figright" style="width: 300px;"><a name="Fig_21a" id="Fig_21a"></a>
+<a href="images/f021-full.jpg"><img src="images/f021.png" width="300" height="511" alt="21. (a) Reduvius personatus,
+nymph.
+Photograph by M. V. S." title="21. (a) Reduvius personatus,
+nymph.
+Photograph by M. V. S." /></a>
+<span class="caption">21. (<i>a</i>)&nbsp;Reduvius personatus,
+nymph.
+Photograph by M. V. S.</span>
+</div>
+
+
+<p><a name="The_Reduviidae_or_assassin-bugs" id="The_Reduviidae_or_assassin-bugs"></a>The <b>Reduviidæ</b>, or <i>assassin-bugs</i> are capable
+of inflicting very painful wounds, as
+most collectors
+of Hemiptera
+know to
+their sorrow.
+Some species are frequently to be
+found in houses and outhouses and
+Dr. Howard suggests that many of
+the stories of painful spider bites
+relate to the attack of these forms.</p>
+
+<div class="figleft" style="width: 375px;">
+<a href="images/f021b-full.jpg"><img src="images/f021b.png" width="375" height="512" alt="21. (b) Reduvius personatus,
+adult (×2)
+Photograph by M. V. S." title="21. (b) Reduvius personatus,
+adult (×2)
+Photograph by M. V. S." /></a>
+<span class="caption">21. (<i>b</i>)&nbsp;Reduvius personatus,
+adult (×2)
+Photograph by M. V. S.</span>
+</div>
+
+<p>An interesting psychological study
+was afforded in the summer of 1899,
+by the "kissing-bug" scare which
+swept over the country. It was
+reported in the daily papers that a
+new and deadly bug had made its
+appearance, which had the unpleasant
+habit of choosing the lips or cheeks<span class="pagenum"><a name="Page_32" id="Page_32">[Pg 32]</a></span>
+for its point of attack on man. So widespread were the stories
+regarding this supposedly new insect that station entomologists all
+over the country began to receive suspected
+specimens for identification. At
+Cornell there were received, among
+others, specimens of stone-flies, may-flies
+and even small moths, with inquiries
+as to whether they were "kissing-bugs."</p>
+
+<div class="figleft" style="width: 300px;"><a name="Fig_22" id="Fig_22"></a>
+<a href="images/f022-full.png"><img src="images/f022.png" width="300" height="391" alt="22. Rasahus biguttatus. (×2). After Howard." title="22. Rasahus biguttatus. (×2). After Howard." /></a>
+<span class="caption">22. Rasahus biguttatus. (×2). After Howard.</span>
+</div>
+
+<p>Dr. L.&nbsp;O. Howard has shown that the
+scare had its origin in newspaper reports
+of some instances of bites by either
+<i>Melanolestes picipes</i> (<a href="#Fig_19">fig.&nbsp;19a</a>) or <i>Opsicoetes
+personatus</i> (<a href="#Fig_20">fig.&nbsp;20</a>), in the vicinity
+of Washington, D.&nbsp;C. He then discusses
+in considerable detail the more prominent
+of the Reduviidæ which, with
+greater or less frequency pierce the skin
+of human beings. These are <i>Opsicoetes personatus</i>, <i>Melanolestes
+picipes</i>, <i>Coriscus subcoleoptratus</i> (<a href="#Fig_19">fig.&nbsp;19<i>g</i></a>), <i>Rasahus thoracicus</i>,
+<i>Rasahus biguttatus</i> (<a href="#Fig_22">fig.&nbsp;22</a>), <i>Conorhinus sanguisugus</i> (<a href="#Fig_71">fig.&nbsp;71</a>), and <span title="for C. (Conorhinus) abdominalis read Melanolestes abdominalis"><a name="AC_3" id="AC_3"></a><i>C.
+abdominalis</i></span> (<a href="#Fig_23">fig.&nbsp;23</a>).</p>
+
+<div class="figright" style="width: 400px;"><a name="Fig_23" id="Fig_23"></a>
+<a href="images/f023-full.png"><img src="images/f023.png" width="400" height="386" alt="23. Conorhinus abdominalis (×2). After
+Marlatt." title="23. Conorhinus abdominalis (×2). After
+Marlatt." /></a>
+<span class="caption">23. <span title="for C. (Conorhinus) abdominalis read Melanolestes abdominalis">Conorhinus abdominalis</span> (×2). After
+Marlatt.</span>
+</div>
+
+<p>One of the most interesting of these species is <i>Reduvius personatus</i>,
+(= <i>Opsic&oelig;tus personatus</i>), which is popularly known as the "masked
+bed-bug hunter." It owes this
+name to the fact that the immature
+nymphs (<a href="#Fig_21a">fig.&nbsp;21</a>) have their
+bodies and legs completely covered
+by dust and lint, and that they
+are supposed to prey upon bed-bugs.
+LeConte is quoted by Howard
+as stating that "This species is
+remarkable for the intense pain
+caused by its bite. I do not know
+whether it ever willingly plunges
+its rostrum into any person, but
+when caught, or unskilfully handled
+it always stings. In this case the
+pain is almost equal to the bite of a snake, and the swelling and
+irritation which result from it will sometimes last for a week."<span class="pagenum"><a name="Page_33" id="Page_33">[Pg 33]</a></span></p>
+
+<p>A species which very commonly attacks man is <i>Conorhinus
+sanguisugus</i>, the so-called "big bed-bug" of the south and southern
+United States. It is frequently found in houses and is known to
+inflict an exceedingly painful bite. As in the case of a number of
+other predaceous Hemiptera, the salivary glands of these forms are
+highly developed. The effect of the bite on their prey and, as Marlatt
+has pointed out, the constant and uniform character of the symptoms
+in nearly all cases of bites in man, clearly indicate that their saliva
+contains a specific substance. No satisfactory studies of the secretions
+have been made. On the other hand, Dr. Howard is doubtless
+right in maintaining that the very serious results which sometimes
+follow the bite are due to the introduction of extraneous poison
+germs. This is borne out by the symptoms of most of the cases
+cited in literature and also by the fact that treatment with corrosive
+sublimate, locally applied to the wound, has yielded favorable results.</p>
+
+
+<p><a name="Other_Hemiptera_Reported_as_Poisonous_to_Man" id="Other_Hemiptera_Reported_as_Poisonous_to_Man"></a><b>Other Hemiptera Reported as Poisonous to Man</b>&mdash;A large number
+of other Hemiptera have been reported as attacking man. Of these,
+there are several species of Lygæidæ, Coreidæ, and Capsidæ. Of the
+latter, <i>Lygus pratensis</i>, the tarnished plant-bug, is reported by
+Professor Crosby as sucking blood. <i>Orthotylus flavosparsus</i> is another
+Capsid which has been implicated. <i>Empoasca mali</i> and <i>Platymetopius
+acutus</i> of the Jassidæ have also been reported as having similar
+habits.</p>
+
+<p>Whenever the periodical cicada or "seventeen-year locust" becomes
+abundant, the newspapers contain accounts of serious results
+from its bites. The senior author has made scores of attempts to
+induce this species to bite and only once successfully. At that
+time the bite was in no wise more severe than a pin-prick. A student
+in our department reports a similar experience. There is no
+case on record which bears evidence of being worthy of any credence,
+whatsoever.</p>
+
+<p>Under the heading of poisonous Hemiptera we might consider the
+bed-bugs and the lice. These will be discussed later, as parasites
+and as carriers of disease, and therefore need only be mentioned here.</p>
+
+
+<h3><a name="DIPTERA" id="DIPTERA"></a>DIPTERA</h3>
+
+<p>Several species of blood-sucking Diptera undoubtedly secrete a
+saliva possessing poisonous properties. Chief among these are the
+Culicidæ, or mosquitoes, and the Simuliidæ, or black-flies. As we
+shall consider these forms in detail under the heading of parasitic<span class="pagenum"><a name="Page_34" id="Page_34">[Pg 34]</a></span>
+species and insects transmitting disease, we shall discuss here only
+the poison of the mosquitoes.</p>
+
+<p>It is well known that mosquitoes, when they bite, inject into the
+wound a minute quantity of poison. The effect of this varies according
+to the species of mosquito and also depends very much on the
+susceptibility of the individual. Soon after the bite a sensation of
+itching is noticed and often a wheal, or eminence, is produced on the
+skin, which may increase to a considerable swelling. The scratching
+which is induced may cause a secondary infection and thus lead to
+serious results. Some people seem to acquire an immunity against
+the poison.</p>
+
+<p>The purpose of this irritating fluid may be, as Reaumur suggested,
+to prevent the coagulation of the blood and thus not only to cause
+it to flow freely when the insect bites but to prevent its rapid coagulation
+in the stomach. Obviously, it is not developed as a protective
+fluid, and its presence subjects the group to the additional handicap
+of the vengeance of man.</p>
+
+<div class="figleft" style="width: 425px;"><a name="Fig_24" id="Fig_24"></a>
+<a href="images/f024-full.png"><img src="images/f024.png" width="425" height="150" alt="24. Diagram of a longitudinal section of a mosquito." title="24. Diagram of a longitudinal section of a mosquito." /></a>
+<span class="caption">24. Diagram of a longitudinal section of a mosquito.</span>
+</div>
+
+<p>As to the origin of the poison, there has been little question,
+until recent years, that it was a secretion from the salivary glands.
+Macloskie (1888) showed
+that each gland is subdivided
+into three lobes,
+the middle of which differs
+from the others in having
+evenly granulated contents
+and staining more deeply
+than the others (<a href="#Fig_24">fig.&nbsp;24</a>). This middle lobe he regarded as the source
+of the poison. Bruck, (1911), by the use of water, glycerine, chloroform,
+and other fluids, extracted from the bodies of a large number
+of mosquitoes a toxine which he calls <i>culicin</i>. This he assumes
+comes from the salivary glands. Animal experimentation showed
+that this extract possessed hemolytic powers. Inoculated into the
+experimenter's own skin it produced lesions which behaved exactly
+as do those of mosquito bites.</p>
+
+<p>Similarly, most writers on the subject have concurred with the
+view that the salivary glands are the source of the poison. However,
+recent work, especially that of Nuttall and Shipley (1903),
+and Schaudinn (1904), has shown that the evidence is by no means
+conclusive. Nuttall dissected out six sets (thirty-six acini) of glands
+from freshly killed <i>Culex pipiens</i> and placed them in a drop of salt<span class="pagenum"><a name="Page_35" id="Page_35">[Pg 35]</a></span>
+solution. The drop was allowed to dry, it being thought that the
+salt crystals would facilitate the grinding up of the glands with the
+end of a small glass rod, this being done under microscopic control.
+After grinding up, a small drop of water was added of the size of the
+original drop of saline, and an equal volume of human blood taken
+from the clean finger-tip was quickly mixed therewith, and the whole
+drawn up into a capillary tube. Clotting was not prevented and no
+hemolysis occurred. Salivary gland emulsion added to a dilute
+suspension of corpuscles did not lead to hemolysis. This experiment
+was repeated a number of times, with slight modification, but
+with similar results. The data obtained from the series "do not
+support the hypothesis that the salivary glands, at any rate in <i>Culex
+pipiens</i>, contain a substance which prevents coagulation."</p>
+
+<p>Much more detailed, and the more important experiments made
+along this line, are those of Schaudinn (1904). The results of these
+experiments were published in connection with a technical paper
+on the alternation of generations and of hosts in <i>Trypanosoma</i> and
+<i>Spirochæta</i>, and for this reason seem to have largely escaped the notice
+of entomologists. They are so suggestive that we shall refer to them
+in some detail.</p>
+
+<p>Schaudinn observed that the three &oelig;sophageal diverticula (commonly,
+but incorrectly, known as the "sucking stomach") (<a href="#Fig_24">fig.&nbsp;24</a>)
+usually contain large bubbles of gas and in addition, he always found
+yeast cells. On the ground of numerous observations, Schaudinn
+was convinced that these yeast plants are normal and constant
+commensals of the insect. He regarded them as the cause of the gas
+bubbles to be found in diverticula. It was found that as the insect
+fed, from time to time the abdomen underwent convulsive contractions
+which resulted in the emptying of the &oelig;sophageal diverticula and
+the salivary glands through blood pressure.</p>
+
+<p>In order to test the supposed toxic action of the salivary glands,
+Schaudinn repeatedly introduced them under his skin and that of
+his assistant, in a drop of salt solution, and never obtained a suggestion
+of the irritation following a bite of the insect, even though the
+glands were carefully rubbed to fragments after their implantation.
+Like Nuttall, he failed to get satisfactory evidence that the secretion
+of the salivary glands retarded coagulation of the blood.</p>
+
+<p>He then carefully removed the &oelig;sophageal diverticula with their
+content of yeast and introduced them into an opening in the skin
+of the hand. Within a few seconds there was noticeable the characteristic<span class="pagenum"><a name="Page_36" id="Page_36">[Pg 36]</a></span>
+itching irritation of the mosquito bite; and in a short time
+there appeared reddening and typical swelling. This was usually
+much more severe than after the usual mosquito bite, and the swelling
+persisted and itched longer. This was because by the ordinary
+bite of the mosquito most of the yeast cells are again sucked up,
+while in these experiments they remained in the wound. These
+experiments were repeated a number of times on himself, his assistant
+and others, and always with the same result. From them Schaudinn
+decided that the poisonous action of the mosquito bite is caused by
+an enzyme from a commensal fungus. These conclusions have not,
+as yet, been satisfactorily tested.</p>
+
+<p>Relief from the effect of the mosquito bite may be obtained by
+bathing the swellings with weak ammonia or, according to Howard,
+by using moist soap. The latter is to be rubbed gently on the puncture
+and is said to speedily allay the irritation. Howard also quotes
+from the <i>Journal of Tropical Medicine and Hygiene</i> to the effect that
+a few drops of a solution of thirty to forty grains of iodine to an ounce
+of saponated petroleum rubbed into the mosquito bite, or wasp sting,
+allay the pain instantaneously.</p>
+
+<p>Methods of mosquito control will be discussed later, in considering
+these insects as parasites and as carriers of disease.</p>
+
+
+<h3><a name="STINGING_INSECTS" id="STINGING_INSECTS"></a>STINGING INSECTS</h3>
+
+<p>The stinging insects all belong to the order <b>Hymenoptera</b>. In a
+number of families of this group the ovipositor is modified to form a
+sting and is connected with poison-secreting glands. We shall
+consider the apparatus of the honey-bee and then make briefer reference
+to that of other forms.</p>
+
+
+<p><a name="Apis_mellifica_the_honey_bee" id="Apis_mellifica_the_honey_bee"></a><b>Apis mellifica, the honey bee</b>&mdash;The sting of the worker honey-bee
+is situated within a so-called sting chamber at the end of the
+abdomen. This chamber is produced by the infolding of the greatly
+reduced and modified eighth, ninth and tenth abdominal segments
+into the seventh.<a name="FNanchor_D_4" id="FNanchor_D_4"></a><a href="#Footnote_D_4" class="fnanchor">[D]</a> From it the dart-like sting can be quickly exserted.</p>
+
+<div class="figright" style="width: 400px;"><a name="Fig_25" id="Fig_25"></a>
+<a href="images/f025-full.png"><img src="images/f025.png" width="400" height="245" alt="25. Sting of a honey bee. Psn Sc, base of acid
+poison gland; B Gl, alkaline poison gland;
+Stn Plp, sting palpi; Sh B, bulb of sting;
+Sh A, basal arm; Lct, lancets or darts; Sh s,
+shaft of sting. Modified from Snodgrass." title="25. Sting of a honey bee. Psn Sc, base of acid
+poison gland; B Gl, alkaline poison gland;
+Stn Plp, sting palpi; Sh B, bulb of sting;
+Sh A, basal arm; Lct, lancets or darts; Sh s,
+shaft of sting. Modified from Snodgrass." /></a>
+<span class="caption">25. Sting of a honey bee. <i>Psn&nbsp;Sc</i>, base of acid
+poison gland; <i>B&nbsp;Gl</i>, alkaline poison gland;
+<i>Stn&nbsp;Plp</i>, sting palpi; <i>Sh&nbsp;B</i>, bulb of sting;
+<i>Sh&nbsp;A</i>, basal arm; <i>Lct</i>, lancets or darts; <i>Sh&nbsp;s</i>,
+shaft of sting. Modified from Snodgrass.</span>
+</div>
+
+<p>The sting (<a href="#Fig_25">fig.&nbsp;25</a>) is made up of a central shaft, ventro-laterad of
+which are the paired <i>lancets</i>, or darts, which are provided with sharp,
+recurved teeth. Still further laterad lie the paired whitish, finger-like<span class="pagenum"><a name="Page_37" id="Page_37">[Pg 37]</a></span>
+<i>sting palpi</i>. Comparative morphological as well as embryological
+studies have clearly established that these three parts correspond
+to the three pairs of
+gonopophyses of the ovipositor
+of more generalized insects.</p>
+
+<p>An examination of the internal
+structures (<a href="#Fig_26">fig.&nbsp;26</a>) reveals
+two distinct types of poison
+glands, the acid-secreting and
+the alkaline-secreting glands,
+and a prominent poison reservoir.
+In addition, there is a
+small pair of accessory structures
+which have been called lubricating glands, on account of the
+supposed function of their product. The acid-secreting gland empties
+into the distal end of the poison reservoir which in turn pours the
+secretion into the muscular bulb-like enlargement at the base of the
+shaft. The alkaline secreting gland empties into the bulb ventrad
+of the narrow neck of the reservoir.</p>
+
+<div class="figleft" style="width: 300px;"><a name="Fig_26" id="Fig_26"></a>
+<a href="images/f026-full.png"><img src="images/f026.png" width="300" height="438" alt="26. Poison apparatus of a honey
+bee. Modified from Snodgrass." title="26. Poison apparatus of a honey
+bee. Modified from Snodgrass." /></a>
+<span class="caption">26. Poison apparatus of a honey
+bee. Modified from Snodgrass.</span>
+</div>
+
+<p>The poison is usually referred to as formic acid. That it is not so
+easily explained has been repeatedly shown and is evidenced by the
+presence of the two types of glands. Carlet maintains that the product
+of either gland is in itself innocent,&mdash;it
+is only when they are combined that
+the toxic properties appear.</p>
+
+<p>The most detailed study of the poison
+of the honey-bee is that of Josef Langer
+(1897), who in the course of his work used
+some 25,000 bees. Various methods of
+obtaining the active poison for experimental
+purposes were used. For obtaining
+the pure secretion, bees were held in the
+fingers and compressed until the sting was
+exserted, when a clear drop of the poison
+was visible at its tip. This was then taken
+up in a capillary tube or dilute solutions
+obtained by dipping the tip of the sting into
+a definite amount of distilled water.</p>
+
+<p>An aqueous solution of the poison was more readily obtained by
+pulling out the sting and poison sacs by means of forceps, and grinding<span class="pagenum"><a name="Page_38" id="Page_38">[Pg 38]</a></span>
+them up in water. The somewhat clouded fluid was then filtered
+one or more times. For obtaining still greater quantities, advantage
+was taken of the fact that while alcohol coagulates the poison, the
+active principle remains soluble in water. Hence the stings with
+the annexed glands where collected in 96 per cent alcohol, after
+filtering off of the alcohol were dried at 40° C., then rubbed to a fine
+powder and this was repeatedly extracted with water. Through
+filtering of this aqueous extract there was obtained a yellowish-brown
+fluid which produced the typical reactions, according to concentration
+of the poison.</p>
+
+<p>The freshly expelled drop of poison is limpid, of distinct acid
+reaction, tastes bitter and has a delicate aromatic odor. On evaporation,
+it leaves a sticky residue, which at 100 degrees becomes fissured,
+and suggests dried gum arabic. The poison is readily soluble in
+water and possesses a specific gravity of 1.1313. On drying at room
+temperature, it leaves a residue of 30 per cent, which has not lost in
+poisonous action or in solubility. In spite of extended experiments,
+Langer was unable to determine the nature of the active principle.
+He showed that it was not, as had been supposed, an albuminous
+body, but rather an organic base.</p>
+
+<p>The pure poison, or the two per cent aqueous solution, placed on
+the uninjured skin showed absolutely no irritating effect, though it
+produced a marked reaction on the mucus membrane of the nose or
+eye. A single drop of one-tenth per cent aqueous solution of the
+poison brought about a typical irritation in the conjunctiva of the
+rabbit's eye. On the other hand, the application of a drop of the
+poison, or its solution, to the slightest break in the skin, or by means
+of a needle piercing the skin, produced typical effects. There is produced
+a local necrosis, in the neighborhood of which there is infiltration
+of lymphocytes, &oelig;dema, and hyperæmia.</p>
+
+<p>The effect of the sting on man (<a href="#Fig_27">fig.&nbsp;27</a>) is usually transitory but
+there are some individuals who are made sick for hours, by a single
+sting. Much depends, too, on the place struck. It is a common
+experience that an angry bee will attempt to reach the eye of its
+victim and a sting on the lid may result in severe and prolonged
+swelling. In the case of a man stung on the cheek, Legiehn observed
+complete aphonia and a breaking out of red blotches all over the
+body. A sting on the tongue has been known to cause such collateral
+&oelig;dema as to endanger life through suffocation. Cases of death of
+man from the attacks of bees are rare but are not unknown. Such<span class="pagenum"><a name="Page_39" id="Page_39">[Pg 39]</a></span>
+results are usually from a number of stings but, rarely, death has
+been known to follow a single sting, entering a blood vessel of a
+particularly susceptible individual.</p>
+
+<div class="figcenter" style="width: 425px;"><a name="Fig_27" id="Fig_27"></a>
+<a href="images/f027-full.png"><img src="images/f027.png" width="425" height="407" alt="Effect of bee stings. After Root." title="Effect of bee stings. After Root." /></a>
+<span class="caption">Effect of bee stings. After Root.</span>
+</div>
+
+<p>It is clearly established that partial immunity from the effects
+of the poison may be acquired. By repeated injections of the venom,
+mice have been rendered capable of bearing doses that certainly
+would have killed them at first. It is a well-known fact that most
+bee-keepers become gradually hardened to the stings, so that the
+irritation and the swelling become less and less. Some individuals
+have found this immunity a temporary one, to be reacquired each
+season. A striking case of acquired immunity is related by the
+Roots in their "A B C and X Y Z of Bee Culture." The evidence
+in the case is so clear that it should be made more widely available
+and hence we quote it here.</p>
+
+<p>A young man who was determined to become a bee-keeper, was so
+susceptible to the poison that he was most seriously affected by a
+single sting, his body breaking out with red blotches, breathing growing
+difficult, and his heart action being painfully accelerated. "We
+finally suggested taking a live bee and pressing it on the back of his
+hand until it merely pierced his skin with the sting, then immediately
+brushing off both bee and sting. This was done and since no serious
+effect followed, it was repeated inside of four or five days. This
+was continued for some three or four weeks, when the patient began to
+have a sort of itching sensation all over his body. The hypodermic<span class="pagenum"><a name="Page_40" id="Page_40">[Pg 40]</a></span>
+injections of bee-sting poison were then discontinued. At the end
+of a month they were repeated at intervals of four or five days.
+Again, after two or three weeks the itching sensation came on, but
+it was less pronounced. The patient was given a rest of about a
+month, when the doses were repeated as before." By this course
+of treatment the young man became so thoroughly immunized that
+neither unpleasant results nor swelling followed the attacks of the
+insects and he is able to handle bees with the same freedom that any
+experienced bee-keeper does.</p>
+
+<p>In an interesting article in the <i>Entomological News</i> for November,
+1914, J. H. Lovell calls attention to the fact that "There has been a
+widespread belief among apiarists that a beekeeper will receive more
+stings when dressed in black than when wearing white clothing.
+A large amount of evidence has been published in the various bee
+journals showing beyond question that honey-bees under certain
+conditions discriminate against black. A few instances may be
+cited in illustration. Of a flock of twelve chickens running in a bee-yard
+seven black ones were stung to death, while five light colored
+ones escaped uninjured. A white dog ran among the bee-hives
+without attracting much attention, while at the same time a black
+dog was furiously assailed by the bees. Mr. J. D. Byer, a prominent
+Canadian beekeeper, relates that a black and white cow, tethered
+about forty feet from an apiary, was one afternoon attacked and
+badly stung by bees. On examination it was found that the black
+spots had five or six stings to one on the white. All noticed this fact,
+although no one was able to offer any explanation. A white horse
+is in much less danger of being stung, when driven near an apiary,
+than a black one. It has, indeed, been observed repeatedly that
+domestic animals of all kinds, if wholly or partially black, are much
+more liable to be attacked by bees, if they wander among the hives,
+than those which are entirely white."</p>
+
+<p>In order to test the matter experimentally, the following series
+of experiments was performed. In the language of the investigator:</p>
+
+<p>"On a clear, warm day in August I dressed wholly in white with
+the exception of a black veil. Midway on the sleeve of my right arm
+there was sewed a band of black cloth ten inches wide. I then
+entered the bee-yard and, removing the cover from one of the hives,
+lifted a piece of comb with both hands and gently shook it. Instantly
+many of the bees flew to the black band, which they continued to<span class="pagenum"><a name="Page_41" id="Page_41">[Pg 41]</a></span>
+attack as long as they were disturbed. Not a single bee attempted
+to sting the left sleeve, which was of course entirely white, and very
+few even alighted upon it."</p>
+
+<p>"This experiment was repeated a second, third and fourth time;
+in each instance with similar results. I estimated the number of bees
+on the band of black cloth at various moments was from thirty to
+forty; it was evident from their behavior that they were extremely
+irritable. To the left white sleeve and other portions of my clothing
+they paid very little attention; but the black veil was very frequently
+attacked."</p>
+
+<p>"A few days later the experiments were repeated, but the band of
+black cloth, ten inches wide, was sewed around my left arm instead
+of around the right arm as before. When the bees were disturbed,
+after the hive cover had been removed, they fiercely attacked the
+band of black cloth as in the previous experiences; but the right white
+sleeve and the white suit were scarcely noticed. At one time a part
+of the black cloth was almost literally covered with furiously stinging
+bees, and the black veil was assailed by hundreds. The bees behaved
+in a similar manner when a second hive on the opposite side of the
+apiary was opened."</p>
+
+<p>"A white veil which had been procured for this purpose, was next
+substituted for the black veil. The result was most surprising,
+for, whereas in the previous experiments hundreds of bees had
+attacked the black veil, so few flew against the white veil as to cause
+me no inconvenience. Undoubtedly beekeepers will find it greatly
+to their advantage to wear white clothing when working among their
+colonies of bees and manipulating the frames of the hives."</p>
+
+<p>When a honey-bee stings, the tip of the abdomen, with the entire
+sting apparatus, is torn off and remains in the wound. Here the
+muscles continue to contract, for some minutes, forcing the barbs
+deeper and deeper into the skin, and forcing out additional poison
+from the reservoir.</p>
+
+<p>Treatment, therefore, first consists in removing the sting without
+squeezing out additional poison. This is accomplished by lifting
+and scraping it out with a knife-blade or the fingernail instead of
+grasping and pulling it out. Local application of alkalines, such as
+weak ammonia, are often recommended on the assumption that the
+poison is an acid to be neutralized on this manner, but these are of
+little or no avail. They should certainly not be rubbed in, as that
+would only accelerate the absorption of the poison. The use of<span class="pagenum"><a name="Page_42" id="Page_42">[Pg 42]</a></span>
+cloths wrung out in hot water and applied as hot as can be borne,
+affords much relief in the case of severe stings. The application of
+wet clay, or of the end of a freshly cut potato is sometimes helpful.</p>
+
+<p>In extreme cases, where there is great susceptibility, or where
+there may have been many stings, a physician should be called. He
+may find strychnine injections or other treatment necessary, if
+general symptoms develop.</p>
+
+<div class="figcenter" style="width: 300px;"><a name="Fig_28" id="Fig_28"></a>
+<a href="images/f028-full.png"><img src="images/f028.png" width="300" height="215" alt="28. The poison apparatus of Formica. Wheeler, after Forel." title="28. The poison apparatus of Formica. Wheeler, after Forel." /></a>
+<span class="caption">28. The poison apparatus of Formica. Wheeler, after Forel.</span>
+</div>
+
+
+<p><a name="Other_Stinging_Forms" id="Other_Stinging_Forms"></a><b>Other Stinging Forms</b>&mdash;Of the five thousand, or more, species
+of bees, most possess a sting and poison apparatus and some of the
+larger forms are capable of inflicting a much more painful sting than
+that of the common honey-bee. In fact, some, like the bumble bees,
+possess the advantage that they do not lose the sting from once using
+it, but are capable of driving it in repeatedly. In the tropics there
+are found many species of stingless bees but these are noted for their
+united efforts to drive away intruders by biting. Certain species
+possess a very irritating saliva which they inject into the wounds.</p>
+
+<p>The ants are not ordinarily regarded as worthy of consideration
+under the heading of "stinging insects" but as a matter of fact,
+most of them possess well developed stings and some of them, especially
+in the tropics, are very justly feared. Even those which lack
+the sting possess well-developed poison glands and the parts of the
+entire stinging apparatus, in so far as it is developed in the various
+species, may readily be homologized with those of the honey-bee.<span class="pagenum"><a name="Page_43" id="Page_43">[Pg 43]</a></span></p>
+
+<p>The ants lacking a sting are those of the subfamily <b>Camponotinæ</b>,
+which includes the largest of our local species. It is an interesting
+fact that some of these species possess the largest poison glands and
+reservoir (<a href="#Fig_28">fig.&nbsp;28</a>) and it is found that when they attack an enemy
+they bring the tip of the abdomen forward and spray the poison in
+such a way that it is introduced into the wound made by the powerful
+mandibles.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_29" id="Fig_29"></a>
+<a href="images/f029-full.png"><img src="images/f029.png" width="450" height="367" alt="29. A harmless, but much feared larva, the &quot;tomato worm.&quot;
+Natural size. Photograph by M. V. S." title="29. A harmless, but much feared larva, the &quot;tomato worm.&quot;
+Natural size. Photograph by M. V. S." /></a>
+<span class="caption">29. A harmless, but much feared larva, the &quot;tomato worm.&quot;
+Natural size. Photograph by M. V. S.</span>
+</div>
+
+<p>More feared than any of the other Hymenoptera are the hornets
+and wasps. Of these there are many species, some of which attain
+a large size and are truly formidable. Phisalix (1897), has made a
+study of the venom of the common hornet and finds that, like the
+poison of the honey-bee, it is neither an albuminoid nor an alkaloid.
+Its toxic properties are destroyed at 120° C. Phisalix also says that
+the venom is soluble in alcohol. If this be true, it differs in this
+respect from that of the bee. An interesting phase of the work of
+Phisalix is that several of her experiments go to show that the venom
+of hornets acts as a vaccine against that of vipers.</p>
+
+
+<h3><a name="NETTLING_INSECTS" id="NETTLING_INSECTS"></a>NETTLING INSECTS</h3>
+
+<p>So far, we have considered insects which possess poison glands
+connected with the mouth-parts or a special sting and which actively<span class="pagenum"><a name="Page_44" id="Page_44">[Pg 44]</a></span>
+inject their poison into man. There remain to be considered those
+insects which possess poisonous hairs or body fluids which, under
+favorable circumstances, may act as poisons. To the first of these
+belong primarily the larvæ of certain Lepidoptera.</p>
+
+
+<h3><a name="LEPIDOPTERA" id="LEPIDOPTERA"></a>LEPIDOPTERA</h3>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_30" id="Fig_30"></a>
+<a href="images/f030-full.png"><img src="images/f030.png" width="500" height="353" alt="30. Another innocent but much maligned caterpillar, the larva of the Regal moth.
+Photograph by M. V. S." title="50030. Another innocent but much maligned caterpillar, the larva of the Regal moth.
+Photograph by M. V. S." /></a>
+<span class="caption">30. Another innocent but much maligned caterpillar, the larva of the Regal moth.
+Photograph by M.&nbsp;V.&nbsp;S.</span>
+</div>
+
+<p>When we consider the reputedly poisonous larvæ of moths and
+butterflies, one of the first things to impress us is that we cannot
+judge by mere appearance. Various species of Sphingid, or hawk-moth
+larvæ, bear at the end of the body a chitinous horn, which is
+often referred to as a "sting" and regarded as capable of inflicting
+dangerous wounds. It would seem unnecessary to refer to this
+absurd belief if it were not that each summer the newspapers contain
+supposed accounts of injury from the "tomato worm" (<a href="#Fig_29">fig.&nbsp;29</a>)
+and others of this group. The grotesque, spiny larva (<a href="#Fig_30">fig.&nbsp;30</a>) of
+one of our largest moths, <i>Citheronia regalis</i> is much feared though
+perfectly harmless, and similar instances could be multiplied.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_31a" id="Fig_31a"></a>
+<a href="images/f031a-full.png"><img src="images/f031a.png" width="500" height="361" alt="31. The flannel moth (Lagoa crispata). (a) Poisonous larva." title="31. The flannel moth (Lagoa crispata). (a) Poisonous larva." /></a>
+<span class="caption">31. The flannel moth (Lagoa crispata). (<i>a</i>) Poisonous larva.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;">
+<a href="images/f031b-full.png"><img src="images/f031b.png" width="400" height="323" alt="31. (b) Adult. Enlarged. Photographs by M. V. S." title="31. (b) Adult. Enlarged. Photographs by M. V. S." /></a>
+<span class="caption">31. (<i>b</i>) Adult. Enlarged. Photographs by M.&nbsp;V.&nbsp;S.</span>
+</div>
+
+<div class="figcenter" style="width: 396px;"><a name="Fig_32" id="Fig_32"></a>
+<a href="images/f032-full.png"><img src="images/f032.png" width="396" height="372" alt="32. The poisonous saddle back caterpillar. Empretia
+(Sibine) stimulea. Photograph by M. V. S." title="32. The poisonous saddle back caterpillar. Empretia
+(Sibine) stimulea. Photograph by M. V. S." /></a>
+<span class="caption">32. The poisonous saddle back caterpillar. Empretia
+(Sibine) stimulea. Photograph by M. V. S.</span>
+</div>
+
+<p>But if the larvæ are often misjudged on account of their ferocious
+appearance, the reverse may be true. A group of most innocent
+looking and attractive caterpillars is that of the flannel-moth larvæ,<span class="pagenum"><a name="Page_45" id="Page_45">[Pg 45]</a></span>
+of which <i>Lagoa crispata</i> may be taken as an example. Its larva
+(<a href="#Fig_31a">fig.&nbsp;31</a>) has a very short and thick body, which is fleshy and completely
+covered and hidden by long silken hairs of a tawny or brown
+color, giving a convex form to the upper side. Interspersed among<span class="pagenum"><a name="Page_46" id="Page_46">[Pg 46]</a></span>
+these long hairs are numerous
+short spines connected
+with underlying hypodermal
+poison glands. These
+hairs are capable of producing
+a marked nettling
+effect when they come in
+contact with the skin.
+This species is found in
+our Atlantic and Southern
+States. Satisfactory
+studies of its poisonous
+hairs and their glands have
+not yet been made.</p>
+
+<div class="figcenter" style="width: 350px;">
+<a href="images/f033a-full.png"><img src="images/f033a.png" width="350" height="368" alt="33a. Io moth larvæ on willow. Photograph by M. V. S." title="33a. Io moth larvæ on willow. Photograph by M. V. S." /></a>
+<span class="caption">33<i>a</i>. Io moth larvæ on willow. Photograph by M.&nbsp;V.&nbsp;S.</span>
+</div>
+
+<p><i>Sibine stimulea (Empretia stimulea)</i>, or the
+saddle-back caterpillar
+(<a href="#Fig_32">fig.&nbsp;32</a>), is another which possesses nettling hairs. This species
+belongs to the group of Eucleidæ, or slug caterpillars. It can be
+readily recognized
+by its flattened
+form, lateral, bristling
+spines and by
+the large green
+patch on the back
+resembling a
+saddle-cloth, while
+the saddle is represented
+by an oval,
+purplish-brown
+spot. The small
+spines are venomous
+and affect
+some persons very
+painfully. The
+larva feeds on the
+leaves of a large
+variety of forest
+trees and also on
+cherry, plum, and<span class="pagenum"><a name="Page_47" id="Page_47">[Pg 47]</a></span>
+even corn leaves. It is to be found throughout the Eastern and
+Southern United States.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_33b" id="Fig_33b"></a>
+<a href="images/f033b-full.png"><img src="images/f033b.png" width="350" height="281" alt="33b. Io moth. Full grown larva. Photograph by M. V. S." title="33b. Io moth. Full grown larva. Photograph by M. V. S." /></a>
+<span class="caption">33<i>b</i>. Io moth. Full grown larva. Photograph by M. V. S.</span>
+</div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_33c" id="Fig_33c"></a>
+<a href="images/f033c-full.png"><img src="images/f033c.png" width="350" height="237" alt="33c. Io moth. Adult. Photograph by M. V. S." title="33c. Io moth. Adult. Photograph by M. V. S." /></a>
+<span class="caption"><span title="for 33c read 34">33<i>c</i>.</span> Io moth. Adult. Photograph by M. V. S.</span>
+</div>
+
+<p><i>Automeris io</i> is the best known of the nettling caterpillars. It is
+the larva of the Io moth, one of the Saturniidæ. The mature caterpillar,
+(<a href="#Fig_33b">fig.&nbsp;33</a>), which reaches a length of two and one-half inches, is
+of a beautiful pale green with sublateral stripes of cream and red color
+and a few black spines among the green ones. The green radiating
+spines give the body a mossy appearance. They are tipped with a<span class="pagenum"><a name="Page_48" id="Page_48">[Pg 48]</a></span>
+slender chitinous hair whose tip is readily broken off in the skin and
+whose poisonous content causes great irritation. Some individuals
+are very susceptible to the poison, while others are able to handle
+the larvæ freely without any discomfort. The larvæ feed on a wide
+range of food plants. They are most commonly encountered on
+corn and on willow, because of the opportunities for coming in contact
+with them.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_35" id="Fig_35"></a>
+<a href="images/f035-full.png"><img src="images/f035.png" width="350" height="258" alt="35. Larva of brown-tail moth. (Natural size). Photograph by M. V. S." title="35. Larva of brown-tail moth. (Natural size). Photograph by M. V. S." /></a>
+<span class="caption">35. Larva of brown-tail moth. (Natural size). Photograph by M. V. S.</span>
+</div>
+
+<p>The larvæ of the brown-tail moth (<i>Euproctis chrysorrh&oelig;a</i>) (fig.&nbsp;<a href="#Fig_35">35</a>
+and&nbsp;<a href="#Fig_36">36</a>), where they occur in this country, are, on account of their
+great numbers, the most serious of all poisonous caterpillars. It is
+not necessary here, to go into details regarding the introduction of
+this species from Europe into the New England States. This is all
+available in the literature from the United States Bureau of Entomology
+and from that of the various states which are fighting the species.
+Suffice to say, there is every prospect that the pest will continue to
+spread throughout the Eastern United States and Canada and that
+wherever it goes it will prove a direct pest to man as well as to his
+plants.</p>
+
+<p>Very soon after the introduction of the species there occurred in
+the region where it had gained a foothold, a mysterious dermatitis of
+man. The breaking out which usually occurred on the neck or other
+exposed part of the body was always accompanied by an intense<span class="pagenum"><a name="Page_49" id="Page_49">[Pg 49]</a></span>
+itching. It was soon found that this dermatitis was caused by certain
+short, barbed hairs of the brown-tail caterpillars and that not only the
+caterpillars but their cocoons and even the adult female moths might
+harbor these nettling hairs and thus give rise to the irritation. In
+many cases the hairs were wafted to clothing on the line and when this
+was worn it might cause the same trouble. Still worse, it was found
+that very serious internal injury was often caused by breathing or
+swallowing the poisonous hairs.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_36" id="Fig_36"></a>
+<a href="images/f036-full.png"><img src="images/f036.png" width="350" height="292" alt="36. Browntail moths. One male and two females. Photograph by
+M. V. S." title="36. Browntail moths. One male and two females. Photograph by
+M. V. S." /></a>
+<span class="caption">36. Browntail moths. One male and two females. Photograph by
+M.&nbsp;V.&nbsp;S.</span>
+</div>
+
+<div class="figleft" style="width: 400px;"><a name="Fig_37a" id="Fig_37a"></a>
+<a href="images/f037a-full.png"><img src="images/f037a.png" width="400" height="341" alt="37. (a) Ordinary hairs and three poison hairs of subdorsal
+and lateral tubercles of the larva of the
+browntail moth. Drawing by Miss Kephart." title="37. (a) Ordinary hairs and three poison hairs of subdorsal
+and lateral tubercles of the larva of the
+browntail moth. Drawing by Miss Kephart." /></a>
+<span class="caption">37. (<i>a</i>)&nbsp;Ordinary hairs and three poison hairs of subdorsal
+and lateral tubercles of the larva of the
+browntail moth. Drawing by Miss Kephart.</span>
+</div>
+
+<p>The earlier studies seemed to indicate that the irritation was
+purely mechanical in origin, the result of the minute barbed hairs
+working into the skin in large numbers. Subsequently, however,
+Dr. Tyzzer (1907) demonstrated beyond question that the trouble
+was due to a poison contained in the hairs. In the first place, it is
+only the peculiar short barbed hairs which will produce the dermatitis
+when rubbed on the skin, although most of the other hairs are sharply
+barbed. Moreover, it was found that in various ways the nettling
+properties could be destroyed without modifying the structure of the
+hairs. This was accomplished by baking for one hour at 110° C, by
+warming to 60° C in distilled water, or by soaking in one per cent. or in
+one-tenth per cent. of potassium hydrate or sodium hydrate. The
+most significant part of his work was the demonstration of the fact<span class="pagenum"><a name="Page_50" id="Page_50">[Pg 50]</a></span>
+that if the nettling hairs are mingled with blood, they immediately
+produce a change in the red corpuscles. These at once become
+coarsely crenated, and the
+roleaux are broken up in the
+vicinity of the hair (<a href="#Fig_37b">fig.&nbsp;37<i>b</i></a>).
+The corpuscles decrease in
+size, the coarse crenations
+are transformed into slender
+spines which rapidly disappear,
+leaving the corpuscles
+in the form of spheres, the
+light refraction of which contrasts
+them sharply with the
+normal corpuscles. The
+reaction always begins at the
+basal sharp point of the hair.
+It could not be produced by
+purely mechanical means, such as the mingling of minute particles
+of glass wool, the barbed hairs of a tussock moth, or the other
+coarser hairs of the brown-tail, with the blood.</p>
+
+<p>The question of the source of the poison has been studied in our
+laboratory by Miss Cornelia
+Kephart. She first confirmed
+Dr. Tyzzer's general results
+and then studied carefully fixed
+specimens of the larvæ to
+determine the distribution of
+the hairs and their relation to
+the underlying tissues.</p>
+
+<div class="figcenter" style="width: 360px;"><a name="Fig_37b" id="Fig_37b"></a>
+<a href="images/f037b-full.png"><img src="images/f037b.png" width="360" height="391" alt="37. (b) Effect of the poison on the blood corpuscles
+of man. After Tyzzer." title="37. (b) Effect of the poison on the blood corpuscles
+of man. After Tyzzer." /></a>
+<span class="caption">37. (<i>b</i>)&nbsp;Effect of the poison on the blood corpuscles
+of man. After Tyzzer.</span>
+</div>
+
+<p>The poison hairs (<a href="#Fig_37a">fig.&nbsp;37</a>),
+are found on the subdorsal
+and lateral tubercles (<a href="#Fig_38">fig.&nbsp;38</a>),
+in bunches of from three to
+twelve on the minute papillæ
+with which the tubercles are
+thickly covered. The underlying
+hypodermis is very
+greatly thickened, the cells
+being three or four times the length of the ordinary hypodermal
+cells and being closely crowded together. Instead of a pore canal<span class="pagenum"><a name="Page_51" id="Page_51">[Pg 51]</a></span>
+through the cuticula for each individual hair, there is a single pore
+for each papillæ on a tubercle, all the hairs of the papilla being
+connected with the
+underlying cells
+through the same
+pore canal, (figs.
+<a href="#Fig_39">39</a>&nbsp;and&nbsp;<a href="#Fig_40">40</a>).</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_38" id="Fig_38"></a>
+<a href="images/f038-full.png"><img src="images/f038.png" width="500" height="352" alt="38. Cross section of the larva of the browntail moth showing the
+tubercles bearing the poison hairs. Drawing by Miss
+Kephart." title="38. Cross section of the larva of the browntail moth showing the
+tubercles bearing the poison hairs. Drawing by Miss
+Kephart." /></a>
+<span class="caption">38. Cross section of the larva of the browntail moth showing the
+tubercles bearing the poison hairs. Drawing by Miss
+Kephart.</span>
+</div>
+
+<p>The hypodermis
+of this region is of
+two distinct types
+of cells. First,
+there is a group of
+slender fusiform
+cells, one for each
+poison hair on the
+papilla, which are
+the trichogen, or
+hair-formative cells. They are crowded to one side and towards
+the basement membrane by a series of much larger, and more prominent
+cells (<a href="#Fig_40">fig.&nbsp;40</a>), of which there is a single one for each papilla.
+These larger cells have a granular protoplasm with large nuclei and
+are obviously actively secreting. They are so characteristic in
+appearance as to leave no question but that they are the true
+poison glands.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_39" id="Fig_39"></a>
+<a href="images/f039-full.png"><img src="images/f039.png" width="500" height="285" alt="39. Epithelium underlying poison hairs of the larva of the
+browntail moth. Drawing by Miss Kephart." title="39. Epithelium underlying poison hairs of the larva of the
+browntail moth. Drawing by Miss Kephart." /></a>
+<span class="caption">39. Epithelium underlying poison hairs of the larva of the
+browntail moth. Drawing by Miss Kephart.</span>
+</div>
+
+<p>Poisonous larvæ of many other species have been reported from
+Europe and especially from the tropics but the above-mentioned
+species are the more important of those occurring in the United States
+and will serve as types. It should be noted in this connection that<span class="pagenum"><a name="Page_52" id="Page_52">[Pg 52]</a></span>
+through some curious misunderstanding
+G&oelig;ldi (1913)
+has featured the larva of
+<i>Orgyia leucostigma</i>, the white-marked
+tussock moth, as the
+most important of the poisonous
+caterpillars of this
+country. Though there are
+occasional reports of irritation
+from its hairs such cases are
+rare and there is no evidence
+that there is any poison present.
+Indeed, subcutaneous
+implantation of the hairs
+leads to no poisoning, but merely to temporary irritation.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_40" id="Fig_40"></a>
+<a href="images/f040-full.png"><img src="images/f040.png" width="450" height="410" alt="40. Same as figure 39, on larger scale." title="40. Same as figure 39, on larger scale." /></a>
+<span class="caption">40. Same as <a href="#Fig_39">figure 39</a>, on larger scale.</span>
+</div>
+
+<p>Occasionally, the hairs of certain species of caterpillars find lodgement
+in the conjunctiva, cornea, or iris of the eye of man and give
+rise to the condition known as <i>opthalmia nodosa</i>. The essential
+feature of this trouble is a nodular conjunctivitis which simulates
+tuberculosis of the conjunctiva and hence has been called <i>pseudo-tubercular</i>.
+It may be distinguished microscopically by the presence
+of the hairs.</p>
+
+<div class="figcenter" style="width: 375px;"><a name="Fig_41a" id="Fig_41a"></a>
+<a href="images/f041a-full.png"><img src="images/f041a.png" width="375" height="317" alt="41. (a) Nodular conjunctivitis in the eye of a child.
+De Schweinitz and Shumway." title="41. (a) Nodular conjunctivitis in the eye of a child.
+De Schweinitz and Shumway." /></a>
+<span class="caption">41. (<i>a</i>)&nbsp;Nodular conjunctivitis in the eye of a child.
+De Schweinitz and Shumway.</span>
+</div>
+
+<p>Numerous cases of opthalmia nodosa are on record. Of those
+from this country, one of the most interesting is reported by de
+Schweinitz and
+Shumway (1904). It
+is that of a child of
+fifteen years whose
+eye had become inflamed
+owing to the
+presence of some foreign
+body. Downward
+and inward on
+the bulbar conjunctiva
+were a number
+of flattened, grayish-yellow
+nodules, between
+which was a
+marked congestion of
+the conjunctival and<span class="pagenum"><a name="Page_53" id="Page_53">[Pg 53]</a></span>
+episcleral vessels (<a href="#Fig_41a">fig.&nbsp;41<i>a</i></a>). Twenty-seven nodules could be differentiated,
+those directly in the center of the collection being somewhat
+confluent and
+assuming a crescentic
+and circular appearance.
+The nodules
+were excised
+and, on sectioning,
+were found to be
+composed of a layer
+of spindle cells and
+round cells, outside
+of which the tissue
+was condensed into
+a capsule. The
+interior consisted of
+epithelioid cells, between
+which was a
+considerable intercellular
+substance. Directly in the center of a certain number of
+nodules was found the section of a hair (<a href="#Fig_41b">fig.&nbsp;41<i>b</i></a>). The evidence
+indicated that the injury had resulted from playing with caterpillars
+of one of the Arctiid moths, <i>Spilosoma virginica</i>. Other reported
+cases have been caused by the hairs of larvæ of <i>Lasiocampa rubi</i>,
+<i>L. pini</i>, <i>Porthetria dispar</i>, <i>Psilura monacha</i> and <i>Cnethocampa
+processionea</i>.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_41b" id="Fig_41b"></a>
+<a href="images/f041b-full.png"><img src="images/f041b.png" width="350" height="278" alt="41b. Section through one of the nodules showing the caterpillar
+hair. De Schweinitz and Shumway." title="41b. Section through one of the nodules showing the caterpillar
+hair. De Schweinitz and Shumway." /></a>
+<span class="caption">41<i>b</i>. Section through one of the nodules showing the caterpillar
+hair. De Schweinitz and Shumway.</span>
+</div>
+
+
+<p><a name="Relief_from_Poisoning_by_Nettling_Larvae" id="Relief_from_Poisoning_by_Nettling_Larvae"></a><b>Relief from Poisoning by Nettling Larvæ</b>&mdash;The irritation from
+nettling larvæ is often severe and, especially in regions where the
+brown-tail abounds, inquiries as to treatment arise. In general, it
+may be said that cooling lotions afford relief, and that scratching,
+with the possibilities of secondary infection, should be avoided, in
+so far as possible.</p>
+
+<p>Among the remedies usually at hand, weak solutions of ammonia,
+or a paste of ordinary baking soda are helpful. Castellani and Chalmers
+recommend cleaning away the hairs by bathing the region with
+an alkaline lotion, such as two per cent solution of bicarbonate of
+soda, and then applying an ointment of ichthyol (10%).<span class="pagenum"><a name="Page_54" id="Page_54">[Pg 54]</a></span></p>
+
+<p>In the brown-tail district, there are many proprietary remedies of
+which the best ones are essentially the following, as recommended
+by Kirkland (1907):</p>
+
+
+<div class="center">
+<table border="0" cellpadding="4" cellspacing="0" summary="">
+<tr><td align="left">Carbolic acid</td><td align="left">&frac12; drachm.</td></tr>
+<tr><td align="left">Zinc oxide</td><td align="left">&frac12; oz.</td></tr>
+<tr><td align="left">Lime water</td><td align="left">8 oz.</td></tr>
+</table></div>
+
+<p>Shake thoroughly and rub well into the affected parts.</p>
+
+<p>In some cases, and especially where there is danger of secondary
+infection, the use of a weak solution of creoline (one teaspoonful to a
+quart of water), is to be advised.</p>
+
+
+<h3><a name="Vescicating_Insects_and_those_Possessing_Other_Poisons_in_their_Blood_Plasma" id="Vescicating_Insects_and_those_Possessing_Other_Poisons_in_their_Blood_Plasma"></a><span class="smcap">Vescicating Insects and those Possessing Other Poisons in
+their Blood Plasma</span></h3>
+
+<div class="figleft" style="width: 150px;"><a name="Fig_42a" id="Fig_42a"></a>
+<a href="images/f042a-full.png"><img src="images/f042a.png" width="150" height="185" alt="42a. Blister beetle." title="42a. Blister beetle." /></a>
+<span class="caption">42<i>a</i>. Blister beetle.</span>
+</div>
+
+<p>We have seen that certain forms, for example, the
+poisonous spiders, not only secrete a toxine in their
+poison glands, but that such a substance may be extracted
+from other parts of their body, or even their
+eggs. There are many insects which likewise possess a
+poisonous blood plasma. Such forms have been well
+designated by Taschenberg as <i>cryptotoxic</i> (&kappa;&rho;&upsilon;&pi;&tau;&omicron;&sigmaf; =
+hidden). We shall consider a few representative forms.</p>
+
+<div class="figright" style="width: 400px;">
+<a href="images/f042b-full.png"><img src="images/f042b.png" width="400" height="505" alt="42b. An American blister beetle. Meloe angusticollis.
+Photograph by M. V. S." title="42b. An American blister beetle. Meloe angusticollis.
+Photograph by M. V. S." /></a>
+<span class="caption">42<i>b</i>. An American blister beetle. Meloe angusticollis.
+Photograph by M. V. S.</span>
+</div>
+
+
+<p><a name="The_Blister_Beetles" id="The_Blister_Beetles"></a><b>The Blister Beetles</b>&mdash;Foremost
+among the cryptotoxic
+insects are the <i>Meloidæ</i> or
+"blister beetles," to which the
+well-known "Spanish fly" (<a href="#Fig_42a">fig.&nbsp;42<i>a</i></a>),
+formerly very generally
+used in medical practice, belongs.
+The vescicating property
+is due to the presence in the
+blood plasma of a peculiar,
+volatile, crystalline substance
+known as <i>cantharidin</i>, which is
+especially abundant in the reproductive
+organs of the beetle. According
+to Kobert, the amount
+of this varies in different species
+from .4 or .5% to 2.57% of the
+dry weight of the beetle.<span class="pagenum"><a name="Page_55" id="Page_55">[Pg 55]</a></span></p>
+
+<p>While blister beetles have been especially used for external application,
+they are also at times used internally as a stimulant and a
+diuretic. The powder or extract was formerly much in vogue as an
+aphrodisiac, and formed the essential constituent of various philters,
+or "love powders". It is now known that its effects on the reproductive
+organs appear primarily after the kidneys have been affected to
+such an extent as to endanger life, and that many cases of fatal poison
+have been due to its ignorant use.</p>
+
+<p>There are many cases on record of poisoning and death due to
+internal use, and in some instances from merely external application.
+There are not rarely cases of poisoning of cattle from feeding on
+herbage bearing a large number of the beetles and authentic cases are
+known of human beings who have been poisoned by eating the flesh
+of such cattle. Kobert states that the beetles are not poisonous to
+birds but that the flesh of birds which have fed on them is poisonous
+to man, and that if the flesh of chickens or frogs which have fed on
+the cantharidin be fed to cats it causes in them the same symptoms
+as does the cantharidin.</p>
+
+<p>Treatment of cases of cantharidin poison is a matter for a skilled
+physician. Until he can be obtained, emetics should be administered
+and these should be followed by white of egg in water. Oils should
+be avoided, as they hasten the absorption of the poison.</p>
+
+
+<p><a name="Other_Cryptotoxic_Insects" id="Other_Cryptotoxic_Insects"></a><b>Other Cryptotoxic Insects</b>&mdash;Though the blister beetles are the
+best known of the insects with poisonous blood plasma, various
+others have been reported and we shall refer to a few of the best
+authenticated.</p>
+
+<p>One of the most famous is the Chrysomelid beetle, <i>Diamphidia
+simplex</i>, the body fluids of whose larvæ are used by certain South
+African bushmen as an arrow poison. Its action is due to the presence
+of a toxalbumin which exerts a hæmolytic action on the blood, and
+produces inflammation of the subcutaneous connective tissue and
+mucous membranes. Death results from general paralysis. Krause
+(1907) has surmised that the active principle may be a bacterial toxin
+arising from decomposition of the tissues of the larva, but he presents
+no support of this view and it is opposed by all the available evidence.</p>
+
+<p>In China, a bug, <i>Heuchis sanguinea</i>, belonging to the family
+Cicadidæ, is used like the Meloidæ, to produce blistering, and often
+causes poisoning. It has been assumed that its vescicating properties
+are due to cantharidin, but the presence of this substance has not
+been demonstrated.<span class="pagenum"><a name="Page_56" id="Page_56">[Pg 56]</a></span></p>
+
+<p>Certain Aphididæ contain a strongly irritating substance which
+produces, not merely on mucous membranes but on outer skin, a
+characteristic inflammation.</p>
+
+<p>It has been frequently reported that the larvæ of the European
+cabbage butterfly, <i>Pieris brassicæ</i>, accidentally eaten by cows, horses,
+ducks, and other domestic animals, cause severe colic, attempts to
+vomit, paralysis of the hind legs, salivation, and stomatitis. On
+<i>postmortem</i> there are to be found hæmorrhagic gastro-enteritis,
+splenitis, and nephritis. Kobert has recently investigated the subject
+and has found a poisonous substance in the blood of not only the
+larvæ but also the pupæ.<span class="pagenum"><a name="Page_57" id="Page_57">[Pg 57]</a></span></p>
+
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_A_1" id="Footnote_A_1"></a><a href="#FNanchor_A_1"><span class="label">[A]</span></a> This is diametrically opposed to the findings of Bordas (1905) in the case
+of the European <i>Latrodectus 13-guttatus</i>, whose glands are "much larger than
+those of other spiders." From a considerable comparative study, we should also
+unhesitatingly make this statement regarding the glands of our American species,
+<i>L. mactans</i>.</p></div>
+
+<div class="footnote"><p><a name="Footnote_B_2" id="Footnote_B_2"></a><a href="#FNanchor_B_2"><span class="label">[B]</span></a> Dr. E. H. Coleman (Kellogg, 1915) has demonstrated its virulence by a series
+of experiments comparable with those of Kobert.</p></div>
+
+<div class="footnote"><p><a name="Footnote_C_3" id="Footnote_C_3"></a><a href="#FNanchor_C_3"><span class="label">[C]</span></a> According to Stiles, the species occurring in the Northwest which is commonly
+identified as <i>D. venustus</i> should be called <i>D. andersoni</i> (see footnote, chapter 12).</p></div>
+
+<div class="footnote"><p><a name="Footnote_D_4" id="Footnote_D_4"></a><a href="#FNanchor_D_4"><span class="label">[D]</span></a> It should be remembered that in all the higher Hymenoptera the first abdominal
+segment is fused with the thorax and that what is apparently the sixth
+segment is, in reality, the seventh.</p></div>
+</div>
+
+
+<hr style="width: 65%;" />
+<h2><a name="CHAPTER_III" id="CHAPTER_III"></a>CHAPTER III</h2>
+
+<h2>PARASITIC ARTHROPODA AFFECTING MAN</h2>
+
+
+<p>The relation of insects to man as simple parasites has long been
+studied, and until very recent years the bulk of the literature of medical
+entomology referred to this phase of the subject. This is now
+completely overshadowed by the fact that so many of these parasitic
+forms are more than simple parasites, they are transmitters of other
+microscopic parasites which are pathogenic to man. Yet the importance
+of insects as parasites still remains and must be considered in a
+discussion of the relation of insects to the health of man. In taking
+up the subject we shall first consider some general features of the
+phenomenon of animal parasitism.</p>
+
+<p>Parasitism is an adaptation which has originated very often among
+living organisms and in widely separated groups. It would seem
+simple to define what is meant by a "parasite" but, in reality, the
+term is not easily limited. It is often stated that a parasite is "An
+organism which lives at the expense of another," but this definition
+is applicable to a predatory species or, in its broadest sense, to all
+organisms. For our purpose we may say with Braun: "A parasite
+is an organism which, for the purpose of obtaining food, takes up its
+abode, temporarily or permanently, on or within another living
+organism".</p>
+
+<p>Thus, parasitism is a phase of the broad biological phenomenon of
+<i>symbiosis</i>, or living together of organisms. It is distinguished from
+<i>mutualism</i>, or symbiosis in the narrow sense, by the fact that only one
+party to the arrangement obtains any advantage, while the other is
+to a greater or less extent injured.</p>
+
+<p>Of parasites we may distinguish on the basis of their location on or
+in the host, <i>ecto-parasites</i>, which live outside of the body; and <i>endo-parasites</i>,
+which live within the body. On account of their method
+of breathing the parasitic arthropods belong almost exclusively to the
+first of these groups.</p>
+
+<p>On the basis of relation to their host, we find <i>temporary parasites</i>,
+those which seek the host only occasionally, to obtain food; and the
+<i>stationary</i> or <i>permanent</i> parasites which, at least during certain stages,
+do not leave their host.</p>
+
+<p><i>Facultative parasites</i> are forms which are not normally parasitic,
+but which, when accidentally ingested, or otherwise brought into the<span class="pagenum"><a name="Page_58" id="Page_58">[Pg 58]</a></span>
+body, are able to exist for a greater or less period of time in their
+unusual environment. These are generally called in the medical
+literature "pseudoparasites" but the term is an unfortunate one.</p>
+
+<p>We shall now take up the different groups of arthropods, discussing
+the more important of the parasitic forms attacking man. The
+systematic relationship of these forms, and key for determining
+important species will be found in Chapter XII.</p>
+
+
+<h3><a name="Acarina_or_Mites" id="Acarina_or_Mites"></a><span class="smcap">Acarina or Mites</span></h3>
+
+<p>The <b>Acarina</b>, or <i>mites</i>, form a fairly natural group of arachnids,
+characterized, in general, by a sac-like, unsegmented body which is
+generally fused with the cephalothorax. The mouth-parts have been
+united to form a beak or rostrum.</p>
+
+<p>The representatives of this group undergo a marked metamorphosis.
+Commonly, the larvæ on hatching from the egg, possess but
+three pairs of legs, and hence are called <i>hexapod larvæ</i>. After a molt,
+they transform into nymphs which, like the adult, have four pairs of
+legs and are called <i>octopod nymphs</i>. These after a period of growth,
+molt one or more times and, acquiring external sexual organs, become
+adult.</p>
+
+<p>Most of the mites are free-living, but there are many parasitic
+species and as these have originated in widely separated families, the
+Acarina form an especially favorable group for study of the origin of
+parasitism. Such a study has been made by Ewing (1911), who has
+reached the following conclusions:</p>
+
+<p>"We have strong evidence indicating that the parasitic habit has
+originated independently at least eleven times in the phylogeny of the
+Ararina. Among the zoophagous parasites, the parasitic habit has
+been developed from three different types of free-living Acarina:
+(a) predaceous forms, (b) scavengers, (c) forms living upon the juices
+of plants."</p>
+
+<p>Ewing also showed that among the living forms of Acarina we can
+trace out all the stages of advancing parasitism, semiparasitism,
+facultative parasitism, even to the fixed and permanent type, and
+finally to endoparasitism.</p>
+
+<p>Of the many parasitic forms, there are several species which are
+serious parasites of man and we shall consider the more important of
+these. Infestation by mites is technically known as <i>acariasis</i>.<span class="pagenum"><a name="Page_59" id="Page_59">[Pg 59]</a></span></p>
+
+<div class="figcenter" style="width: 225px;"><a name="Fig_43" id="Fig_43"></a>
+<a href="images/f043-full.png"><img src="images/f043.png" width="225" height="373" alt="43. Effect of the harvest mites on the skin of man. Photograph by
+J. C. Bradley." title="43. Effect of the harvest mites on the skin of man. Photograph by
+J. C. Bradley." /></a>
+<span class="caption">43. Effect of the harvest mites on the skin of man. Photograph by
+J. C. Bradley.</span>
+</div><p><span class="pagenum"><a name="Page_60" id="Page_60">[Pg 60]</a></span></p>
+
+
+<h3><a name="The_Trombidiidae_or_Harvest_Mites" id="The_Trombidiidae_or_Harvest_Mites"></a>The Trombidiidæ, or Harvest Mites</h3>
+
+<p>In many parts of this country it is impossible for a visitor to go
+into the fields and, particularly, into berry patches and among tall
+weeds and grass in the summer or early fall without being affected by
+an intolerable itching, which is followed, later, by a breaking out of
+wheals, or papules, surrounded by a bright red or violaceous aureola,
+(<a href="#Fig_43">fig.&nbsp;43</a>). It is often regarded as a urticaria or eczema, produced by
+change of climate, an error in diet, or some condition of general health.</p>
+
+<p>Sooner or later, the victim finds that it is due to none of these, but
+to the attacks of an almost microscopic red mite, usually called
+"jigger" or "chigger" in this country. As the term "chigger" is
+applied to one of the true fleas, <i>Dermatophilus penetrans</i>, of the tropics,
+these forms are more
+correctly known as
+"harvest mites."
+Natives of an infested
+region may be so
+immune or accustomed
+to its attacks
+as to be unaware of
+its presence, though
+such immunity is by
+no means possessed
+by all who have been
+long exposed to the
+annoyance.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_44" id="Fig_44"></a>
+<a href="images/f044-full.png"><img src="images/f044.png" width="500" height="305" alt="44. Harvest mites. (Larvæ of Trombidium). After C. V.
+Riley." title="44. Harvest mites. (Larvæ of Trombidium). After C. V.
+Riley." /></a>
+<span class="caption">44. Harvest mites. (Larvæ of Trombidium). After C. V.
+Riley.</span>
+</div>
+
+<p>The harvest mites, or chiggers, attacking man are larval forms,
+possessing three pairs of legs (<a href="#Fig_44">fig.&nbsp;44</a>). Their systematic position was
+at first unknown and they were classed under a special genus <i>Leptus</i>,
+a name which is very commonly still retained in the medical literature.
+It is now known that they are the larval forms of various species of
+the genus <i>Trombidium</i>, a group of predaceous forms, the adults of
+which feed primarily on insects and their eggs. In this country the
+species best known are those to be found late in summer, as larvæ
+at the base of the wings of houseflies or grasshoppers.</p>
+
+<p>There is much uncertainty as to the species of the larvæ attacking
+man but it is clear that several are implicated. Bruyant has shown
+that in France the larvæ <i>Trombidium inapinatum</i> and <i>Trombidium
+holosericeum</i> are those most frequently found. The habit of attacking
+man is abnormal and the larvæ die after entering the skin. Normally
+they are parasitic on various insects.<span class="pagenum"><a name="Page_61" id="Page_61">[Pg 61]</a></span></p>
+
+<p>Most recent writers agree that, on man, they do not bore into the
+skin, as is generally supposed, but enter a hair follicle or sebaceous
+gland and from the bottom of this, pierce the cutis with their elongate
+hypopharynx. According to Braun, there arises about the inserted
+hypopharynx a fibrous secretion&mdash;the so-called "beak" which is, in
+reality, a product of the host. Dr. J. C. Bradley, however, has made
+careful observations on their method of attack, and he assures us that
+the mite ordinarily remains for a long time feeding on the surface of
+the skin, where it produces the erythema above described. During
+this time it is not buried in the skin but is able to retreat rapidly into
+it through a hair follicle or sweat gland. The irritation from the
+mites ceases after a few days, but not infrequently the intolerable
+itching leads to so much scratching that secondary infection follows.</p>
+
+<p>Relief from the irritation may be afforded by taking a warm salt
+bath as soon as possible after exposure or by killing the mites by
+application of benzine, sulphur ointment or carbolized vaseline.
+When they are few in number, they can be picked out with a sterile
+needle.</p>
+
+<p>Much may be done in the way of warding off their attacks by
+wearing gaiters or close-woven stockings extending from ankle to the
+knee. Still more efficacious is the sprinkling of flowers of sulphur in
+the stockings and the underclothes from a little above the knee, down.
+The writers have known this to make it possible for persons who were
+especially susceptible to work with perfect comfort in badly infested
+regions. Powdered naphthalene is successfully used in the same way
+and as Chittenden (1906) points out, is a safeguard against various
+forms of man-infesting tropical insect pests.</p>
+
+<p>The question of the destruction of the mites in the field is sometimes
+an important one, and under some conditions, is feasible.
+Chittenden states that much can be accomplished by keeping the
+grass, weeds, and useless herbage mowed closely, so as to expose the
+mites to the sun. He believes that in some cases good may be done
+by dusting the grass and other plants, after cutting, with flowers of
+sulphur or by spraying with dilute kerosene emulsion in which
+sulphur has been mixed. More recently (1914) he calls attention to
+the value of cattle, and more especially sheep, in destroying the pests
+by tramping on them and by keeping the grass and herbage closely
+cropped.<span class="pagenum"><a name="Page_62" id="Page_62">[Pg 62]</a></span></p>
+
+
+<h3><a name="Ixodoidea_or_Ticks" id="Ixodoidea_or_Ticks"></a><span class="smcap">Ixodoidea or Ticks</span></h3>
+
+<p>Until recently, the ticks attracted comparatively little attention
+from entomologists. Since their importance as carriers of disease
+has been established, interest in
+the group has been enormously
+stimulated and now they rank
+second only to the mosquitoes
+in the amount of detailed study
+that has been devoted to them.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_45a" id="Fig_45a"></a>
+<a href="images/f045a-full.png"><img src="images/f045a.png" width="450" height="481" alt="45a. Argus persicus. Capitulum of male.
+After Nuttall and Warburton." title="45a. Argus persicus. Capitulum of male.
+After Nuttall and Warburton." /></a>
+<span class="caption">45<i>a</i>. Argus persicus. Capitulum of male.
+After Nuttall and Warburton.</span>
+</div>
+
+<p>The ticks are the largest of
+the Acarina. They are characterized
+by the fact that the
+hypostome, or "tongue" (<a href="#Fig_45a">fig.&nbsp;45</a>)
+is large and file-like, roughened
+by sharp teeth. They possess
+a breathing pore on each side
+of the body, above the third
+or fourth coxæ (<a href="#Fig_45b">fig.&nbsp;45<i>b</i></a>).</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_45b" id="Fig_45b"></a>
+<a href="images/f045b-full.png"><img src="images/f045b.png" width="450" height="398" alt="45b. Left spiracle of nymph of Argas persicus.
+After Nuttall and Warburton." title="45b. Left spiracle of nymph of Argas persicus.
+After Nuttall and Warburton." /></a>
+<span class="caption">45<i>b</i>. Left spiracle of nymph of <i>Argas persicus</i>.
+After Nuttall and Warburton.</span>
+</div>
+
+<p>There are two distinct families
+of the <b>Ixodoidea</b>, differing
+greatly in structure, life-history and habits. These are the <b>Argasidæ</b>
+and the <b>Ixodidæ</b>. We shall follow Nuttall (1908) in characterizing
+these two families and in pointing out their biological differences, and
+shall discuss briefly the more important species which attack man.
+The consideration of the
+ticks as carriers of disease
+will be reserved for a later
+chapter.</p>
+
+
+<h3><a name="Argasidae" id="Argasidae"></a>Argasidæ</h3>
+
+<p>In the ticks belonging to
+the family <b>Argasidæ</b>, there
+is comparatively little sexual
+dimorphism, while this is
+very marked in the Ixodidæ.
+The capitulum, or so-called
+"head" is ventral, instead of
+terminal; the palpi are leg-like,
+with the segments subequal; the scutum, or dorsal shield, is
+absent; eyes, when present, are lateral, on supracoxal folds. The<span class="pagenum"><a name="Page_63" id="Page_63">[Pg 63]</a></span>
+spiracles are very small; coxæ unarmed; tarsi without ventral spurs,
+and the pulvilli are absent or rudimentary.</p>
+
+<p>In habits and life history the Argasidæ present striking characteristics.
+In the first place, they are long-lived, a factor which counts for
+much in the maintenance of the species. They are intermittent
+feeders, being comparable with the bed-bug in this respect. There are
+two or more nymphal stages, and they may molt after attaining maturity.
+The female lays comparatively few eggs in several small batches.</p>
+
+<p>Nuttall (1911) concludes that "The Argasidæ represent the relatively
+primitive type of ticks because they are less constantly parasitic
+than are the Ixodidæ. Their nymphs and adults are rapid
+feeders and chiefly infest the habitat of their hosts. * * * Owing
+to the Argasidæ infesting the habitats of their hosts, their resistance
+to prolonged starvation and their rapid feeding habits, they do not
+need to bring forth a large progeny, because there is less loss of life
+in the various stages, as compared with the Ixodidæ, prior to their
+attaining maturity."</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_46" id="Fig_46"></a>
+<a href="images/f046-full.png"><img src="images/f046.png" width="350" height="264" alt="46. Argus persicus. Dorsal and ventral aspects. (×4). After Hassell." title="46. Argus persicus. Dorsal and ventral aspects. (×4). After Hassell." /></a>
+<span class="caption">46. Argus persicus. Dorsal and ventral aspects. (×4). After Hassell.</span>
+</div>
+
+<p>Of the Argasidæ, we have in the United States, several species
+which have been reported as attacking man.</p>
+
+<div class="figleft" style="width: 300px;"><a name="Fig_47" id="Fig_47"></a>
+<a href="images/f047-full.png"><img src="images/f047.png" width="300" height="354" alt="47. Otiobius (Ornithodoros) megnini, head
+of nymph. After Stiles." title="47. Otiobius (Ornithodoros) megnini, head
+of nymph. After Stiles." /></a>
+<span class="caption">47. Otiobius (Ornithodoros) megnini, head
+of nymph. After Stiles.</span>
+</div>
+
+<p><i>Argas persicus</i>, the famous "Miana bug" (<a href="#Fig_46">fig.&nbsp;46</a>), is a very widely
+distributed species, being reported from Europe, Asia, Africa, and
+Australia. It is everywhere preeminently a parasite of fowls.<span class="pagenum"><a name="Page_64" id="Page_64">[Pg 64]</a></span>
+According to Nuttall it is specifically identical with <i>Argas americanus</i>
+Packard or <i>Argas miniatus</i> Koch, which is commonly found on fowls
+in the United States, in the South
+and Southwest. Its habits are comparable
+to those of the bed-bug. It
+feeds intermittently, primarily at
+night, and instead of remaining on its
+host, it then retreats to cracks and
+crevices. Hunter and Hooker (1908)
+record that they have found the larva
+to remain attached for five or eight
+days before dropping. Unlike the
+Ixodidæ, the adults oviposit frequently.</p>
+
+<p>The most remarkable feature of
+the biology of this species is the great
+longevity, especially of the adult.
+Hunter and Hooker report keeping
+larvæ confined in summer in pill boxes immediately after hatching
+for about two months while under similar conditions those
+of the Ixodid, <i>Boophilus annulatus</i> lived for but two or three days.
+Many writers have recorded keeping adults for long periods without
+food. We have kept specimens in a tin box for over a year and a half
+and at the end of that time a number were still alive. Laboulliene
+kept unfed adults for over three years. In view of the effectiveness of<span class="pagenum"><a name="Page_65" id="Page_65">[Pg 65]</a></span>
+sulphur in warding off the attacks of Trombidiidæ, it is astonishing
+to find that Lounsbury has kept adults of <i>Argas persicus</i> for three
+months in a box nearly filled with flowers of sulphur, with no apparent
+effect on them.</p>
+
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_48" id="Fig_48"></a>
+<a href="images/f048-full.png"><img src="images/f048.png" width="500" height="335" alt="48. Otiobius (Ornithodoros) megnini, male. (a) dorsal, (b) ventral
+aspect. After Nuttall and Warburton." title="48. Otiobius (Ornithodoros) megnini, male. (a) dorsal, (b) ventral
+aspect. After Nuttall and Warburton." /></a>
+<span class="caption">48. Otiobius (Ornithodoros) megnini, male. (<i>a</i>)&nbsp;dorsal, (<i>b</i>)&nbsp;ventral
+aspect. After Nuttall and Warburton.</span>
+</div>
+
+<p>We have already called attention to the occasional serious effects
+of the bites of this species. While such reports have been frequently
+discredited there can be no doubt that they have foundation in fact.
+The readiness with which this tick attacks man, and the extent to
+which old huts may be infested makes it especially troublesome.</p>
+
+<p><i>Otiobius (Ornithodoros) megnini</i>, the "spinose ear-tick" (figs. <a href="#Fig_47">47</a>,&nbsp;<a href="#Fig_48">48</a>),
+first described from Mexico, as occurring in the ears of horses, is a
+common species in our Southwestern States and is recorded by Banks
+as occurring as far north as Iowa.</p>
+
+<p>The species is remarkable for the great difference between the
+spiny nymph stage and the adult. The life history has been worked
+out by Hooker (1908). Seed ticks, having gained entrance to the
+ear, attach deeply down in the folds, engorge, and in about five days,
+molt; as nymphs with their spinose body they appear entirely unlike
+the larvæ. As nymphs they continue feeding sometimes for months.
+Finally the nymph leaves the host, molts to form the unspined adult,
+and without further feeding is fertilized and commences oviposition.</p>
+
+<p>The common name is due to the fact that in the young stage the
+ticks occur in the ear of their hosts, usually horses or cattle. Not
+uncommonly it has been reported as occurring in the ear of man and
+causing very severe pain. Stiles recommends that it be removed by
+pouring some bland oil into the ear.</p>
+
+<p>Banks (1908) reports three species of <i>Ornithodoros</i>&mdash;<i>O. turicata</i>,
+<i>coriaceus</i> and <i>talaje</i>&mdash;as occurring in the United States. All of these
+attack man and are capable of inflicting very painful bites.</p>
+
+
+<h3><a name="Ixodidae" id="Ixodidae"></a>Ixodidæ</h3>
+
+<p>The ticks belonging to the family <b>Ixodidæ</b> (figs. <a href="#Fig_49">49</a>&nbsp;and&nbsp;<a href="#Fig_50">50</a>) exhibit
+a marked sexual dimorphism. The capitulum is anterior, terminal,
+instead of ventral as in the Argasidæ; the palpi are relatively rigid
+(except in the subfamily Ixodinæ), with rudimentary fourth segment;
+scutum present; eyes, when present, dorsal, on side of scutum. The
+spiracles are generally large, situated well behind the fourth coxæ;
+coxæ generally with spurs; pulvilli always present.</p>
+
+<p>In habits and life history the typical Ixodidæ differ greatly from
+the Argasidæ. They are relatively short-lived, though some recent<span class="pagenum"><a name="Page_66" id="Page_66">[Pg 66]</a></span>
+work indicates that their longevity
+has been considerably
+under-estimated. Typically,
+they are permanent feeders,
+remaining on the host, or hosts,
+during the greater part of their
+life. They molt twice only,
+on leaving the larval and the
+nymphal stages. The adult
+female deposits a single, large
+batch of eggs. Contrasting
+the habits of the Ixodidæ to
+those of the Argasidæ, Nuttall
+(1911) emphasizes that the
+Ixodidæ are more highly
+specialized parasites. "The
+majority are parasitic on hosts
+having no fixed habitat and
+consequently all stages, as a
+rule, occur upon the host."</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_49" id="Fig_49"></a>
+<a href="images/f049-full.png"><img src="images/f049.png" width="400" height="524" alt="49. Ixodes ricinus; male, ventral aspect. After
+Braun and Luehe." title="49. Ixodes ricinus; male, ventral aspect. After
+Braun and Luehe." /></a>
+<span class="caption">49. Ixodes ricinus; male, ventral aspect. After
+Braun and Luehe.</span>
+</div>
+
+<p>As mere parasites of man, apart from their power to transmit
+disease, the Ixodidæ are much less important than the Argasidæ.
+Many are reported as occasionally attacking man and of these the
+following native species
+may be mentioned.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_50" id="Fig_50"></a>
+<a href="images/f050-full.png"><img src="images/f050.png" width="500" height="427" alt="50. Ixodes ricinus, var. scapularis, female. Capitulum and
+scutum; ventral aspect of capitulum; coxæ; tarsus 4;
+spiracle; genital and anal grooves. After Nuttall and
+Warburton." title="50. Ixodes ricinus, var. scapularis, female. Capitulum and
+scutum; ventral aspect of capitulum; coxæ; tarsus 4;
+spiracle; genital and anal grooves. After Nuttall and
+Warburton." /></a>
+<span class="caption">50. Ixodes ricinus, var. scapularis, female. Capitulum and
+scutum; ventral aspect of capitulum; coxæ; tarsus&nbsp;4;
+spiracle; genital and anal grooves. After Nuttall and
+Warburton.</span>
+</div>
+
+<p><i>Ixodes ricinus</i>, the
+European castor bean
+tick (figs. <a href="#Fig_49">49</a>,&nbsp;<a href="#Fig_50">50</a>), is a
+species which has been
+often reported from
+this country but Banks
+(1908) has shown that,
+though it does occur,
+practically all of the
+records apply to <i>Ixodes
+scapularis</i> or <i>Ixodes
+cookei</i>. In Europe,
+<i>Ixodes ricinus</i> is very
+abundant and very
+commonly attacks<span class="pagenum"><a name="Page_67" id="Page_67">[Pg 67]</a></span>
+man. At the point of penetration of the hypostome there is more or
+less inflammation but serious injury does not occur unless there have
+been introduced pathogenic bacteria or, unless the tick has been
+abruptly removed, leaving the capitulum in the wound. Under the
+latter circumstances, there may be an abscess formed about the foreign
+body and occasionally, serious results have followed. Under certain
+conditions the tick, in various stages, may penetrate under the skin
+and produce a tumor, within which it may survive for a considerable
+period of time.</p>
+
+<p><i>Ixodes cookei</i> is given by Banks as "common on mammals in the
+Eastern States as far west as the Rockies." It is said to affect man
+severely.</p>
+
+<p><i>Amblyomma americanum</i>, (<a href="#Fig_158">fig.&nbsp;158c</a>), the "lone star tick," is
+widely distributed in the United States. Its common name is derived
+from the single silvery spot on the scutum of the female. Hunter
+and Hooker regard this species as, next to <i>Boophilus annulatus</i>, the
+most important tick in the United States. Though more common on
+cattle, it appears to attack mammals generally, and "in portions of
+Louisiana and Texas it becomes a pest of considerable importance to
+moss gatherers and other persons who spend much time in the forests."</p>
+
+<p><i>Amblyomma cajennense</i>, noted as a pest of man in central and
+tropical America, is reported from various places in the south and
+southwestern United States.</p>
+
+<p><i>Dermacentor variabilis</i> is a common dog tick of the eastern United
+States. It frequently attacks man, but the direct effects of its bite
+are negligible.</p>
+
+<p>The "Rocky Mountain spotted fever tick" (<i>Dermacentor andersoni</i>
+according to Stiles, <i>D. venustus</i> according to Banks) is, from the viewpoint
+of its effects on man, the most important of the ticks of the
+United States. This is because, as has been clearly established, it
+transmits the so-called "spotted fever" of man in our northwestern
+states. This phase of the subject will be discussed later and it need
+merely be mentioned here, that this species has been reported as
+causing painful injuries by its bites. Dr. Stiles states that he has
+seen cases of rather severe lymphangitis and various sores and swellings
+developing from this cause. In one case, of an individual bitten
+near the elbow, the arm became very much swollen and the patient
+was confined in bed for several days. The so-called tick paralysis
+produced by this species is discussed in a preceding chapter.<span class="pagenum"><a name="Page_68" id="Page_68">[Pg 68]</a></span></p>
+
+<p>There are many other records of various species of ticks attacking
+man, but the above-mentioned will serve as typical and it is not necessary
+to enter into greater detail.</p>
+
+
+<p><a name="Treatment_of_Tick_Bites" id="Treatment_of_Tick_Bites"></a><b>Treatment of Tick Bites</b>&mdash;When a tick attaches to man the first
+thing to be done is to remove it without leaving the hypostome in the
+wound to fester and bring about secondary effects. This is best
+accomplished by applying to the tick's body some substance which
+will cause it to more readily loosen its hold. Gasoline or petroleum,
+oil or vaseline will serve.
+For removing the
+spinose ear-tick, Stiles
+recommends pouring
+some bland oil into the
+ear. Others have used
+effectively a pledget of
+cotton soaked in chloroform.</p>
+
+<p>In general, the treatment
+recommended by
+Wellman for the bites
+of <i>Ornithodoros moubata</i>
+will prove helpful. It
+consists of prolonged
+bathing in very hot
+water, followed by the
+application of a strong
+solution of bicarbonate
+of soda, which is allowed to dry upon the skin. He states that this
+treatment is comforting. For severe itching he advises smearing
+the bites with vaseline, which is slightly impregnated with camphor
+or menthol. Medical aid should be sought when complications arise.</p>
+
+<p>The <a name="Dermanyssidae" id="Dermanyssidae"></a><b>Dermanyssidæ</b> are Gamasid mites which differ from others of
+the group in that they are parasitic on vertebrates. None of the
+species normally attack man, but certain of them, especially the
+poultry mite, may be accidental annoyances.</p>
+
+<div class="figcenter" style="width: 475px;"><a name="Fig_51" id="Fig_51"></a>
+<a href="images/f051-full.png"><img src="images/f051.png" width="475" height="473" alt="51. Dermanyssus gallinæ, female. After Delafond." title="51. Dermanyssus gallinæ, female. After Delafond." /></a>
+<span class="caption">51. Dermanyssus gallinæ, female. After Delafond.</span>
+</div>
+
+<p><i>Dermanyssus gallinæ</i> (<a href="#Fig_51">fig.&nbsp;51</a>), the red mite of poultry, is an exceedingly
+common and widespread parasite of fowls. During the day
+it lives in cracks and crevices of poultry houses, under supports of
+roosts, and in litter of the food and nests, coming out at night to feed.<span class="pagenum"><a name="Page_69" id="Page_69">[Pg 69]</a></span>
+They often attack people working in poultry houses or handling and
+plucking infested fowls. They may cause an intense pruritis, but they
+do not produce a true dermatosis, for
+they do not find conditions favorable for
+multiplication on the skin of man.</p>
+
+
+<h3><a name="Tarsonemidae" id="Tarsonemidae"></a>Tarsonemidæ</h3>
+
+<p>The representatives of the family <b>Tarsonemidæ</b>
+are minute mites, with the body
+divided into cephalothorax and abdomen.
+There is marked sexual dimorphism.
+The females possess stigmata at the
+anterior part of the body, at the base of
+the rostrum, and differ from all other mites
+in having on each side, a prominent clavate
+organ between the first and second legs.
+The larva, when it exists, is hexapodous
+and resembles the adult. A number of the
+species are true parasites on insects, while others attack plants.
+Several of them may be accidental parasites of man.</p>
+
+<div class="figcenter" style="width: 275px;"><a name="Fig_52" id="Fig_52"></a>
+<a href="images/f052-full.png"><img src="images/f052.png" width="275" height="421" alt="52. Pediculoides ventricosus, female.
+After Webster." title="52. Pediculoides ventricosus, female.
+After Webster." /></a>
+<span class="caption">52. Pediculoides ventricosus, female.
+After Webster.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_53" id="Fig_53"></a>
+<a href="images/f053-full.png"><img src="images/f053.png" width="400" height="495" alt="53. Pediculoides ventricosus, gravid female. (×80).
+After Webster." title="53. Pediculoides ventricosus, gravid female. (×80).
+After Webster." /></a>
+<span class="caption">53. Pediculoides ventricosus, gravid female. (×80).
+After Webster.</span>
+</div>
+
+<p><i>Pediculoides ventricosus</i>
+(fig. <a href="#Fig_52">52</a>&nbsp;and&nbsp;<a href="#Fig_53">53</a>) is, of all the
+Tarsonemidæ reported, the
+one which has proved most
+troublesome to man. It is a
+predaceous species which
+attacks a large number of
+insects but which has most
+commonly been met with by
+man through its fondness for
+certain grain-infesting insects,
+notably the Angoumois grain
+moth, <i>Sitotroga cerealella</i>, and
+the wheat straw-worm, <i>Isosoma
+grande</i>. In recent years
+it has attracted much attention
+in the United States and
+its distribution and habits
+have been the object of detailed
+study by Webster (1901).<span class="pagenum"><a name="Page_70" id="Page_70">[Pg 70]</a></span></p>
+
+<div class="figcenter" style="width: 250px;"><a name="Fig_54" id="Fig_54"></a>
+<a href="images/f054-full.png"><img src="images/f054.png" width="250" height="264" alt="54. Pediculoides ventricosus, male. After Braun." title="54. Pediculoides ventricosus, male. After Braun." /></a>
+<span class="caption">54. Pediculoides ventricosus, male. After Braun.</span>
+</div>
+
+<p>There is a very striking sexual dimorphism in this species. The
+non-gravid female is elongate, about 200µ by 70µ (<a href="#Fig_52">fig.&nbsp;52</a>), with the
+abdomen slightly striated longitudinally. The gravid female (<a href="#Fig_53">fig.&nbsp;53</a>)
+has the abdomen enormously swollen, so that it is from twenty to a
+hundred times greater than the rest of the body. The species is
+viviparous and the larvæ undergo their entire growth in the body of
+the mother. They emerge as sexually mature males and females
+which soon pair. The male (<a href="#Fig_54">fig.&nbsp;54</a>) is much smaller, reaching a
+length of only 320µ but
+is relatively broad,
+80µ, and angular. Its
+abdomen is very greatly
+reduced.</p>
+
+<p>As far back as 1850
+it was noted as causing
+serious outbreaks
+of peculiar dermatitis
+among men handling
+infested grain. For
+some time the true
+source of the difficulty
+was unknown and it
+was even believed that
+the grain had been
+poisoned. Webster
+has shown that in this
+country (and probably
+in Europe as well) its
+attacks have been mistaken for those of the red bugs or "chiggers"
+(larval Trombiidæ). More recently a number of outbreaks of a
+mysterious "skin disease" were traced to the use of straw mattresses,
+which were found to be swarming with these almost microscopic
+forms which had turned their attentions to the occupants of the beds.
+Other cases cited were those of farmers running wheat through a
+fanning mill, and of thrashers engaged in feeding unthrashed grain
+into the cylinder of the machine.</p>
+
+<div class="figcenter" style="width: 250px;"><a name="Fig_55" id="Fig_55"></a>
+<a href="images/f055-full.png"><img src="images/f055.png" width="250" height="338" alt="55. Lesions produced by the attacks of Pediculoides ventricosus.
+After Webster." title="55. Lesions produced by the attacks of Pediculoides ventricosus.
+After Webster." /></a>
+<span class="caption">55. Lesions produced by the attacks of Pediculoides ventricosus.
+After Webster.</span>
+</div>
+
+<p>The medical aspects of the question have been studied especially
+by Schamberg and Goldberger and from the latter's summary (1910)
+we derive the following data. Within twelve to sixteen hours after
+exposure, itching appears and in severe cases, especially where exposure<span class="pagenum"><a name="Page_71" id="Page_71">[Pg 71]</a></span>
+is continued night after night by sleeping on an infested bed, the
+itching may become almost intolerable. Simultaneously, there
+appears an eruption which characteristically consists of wheals
+surrounded by a vesicle (<a href="#Fig_55">fig.&nbsp;55</a>). The vesicle as a rule does not exceed
+a pin head in size but may become as large as a pea. Its contents
+rapidly become turbid and in a few hours it is converted into a pustule.
+The eruption is most abundant on the trunk, slight on the face and
+extremities and almost absent on the feet and hands. In severe cases
+there may be constitutional disturbances marked, at the outset, by
+chilliness, nausea, and vomiting, followed for a few days by a slight
+elevation of temperature, with the appearance of albumin in the
+urine. In some cases the eruption may simulate that of chicken-pox
+or small-pox.<span class="pagenum"><a name="Page_72" id="Page_72">[Pg 72]</a></span></p>
+
+<p>Treatment for the purpose of killing the mites is hardly necessary
+as they attach feebly to the surface and are readily brushed off by
+friction of the clothes. "Antipruritic treatment is always called for;
+warm, mildly alkaline baths or some soothing ointment, such as zinc
+oxide will be found to fulfil this indication." Of course, reinfestation
+must be guarded against, by discarding, or thoroughly fumigating
+infested mattresses, or by avoiding other sources. Goldberger suggests
+that farm laborers who must work with infested wheat or straw
+might protect themselves by anointing the body freely with some
+bland oil or grease, followed by a change of clothes and bath as soon
+as their work is done. We are not aware of any experiments to
+determine the effect of flowers of sulphur, but their efficiency in the
+case of "red bugs" suggests that they are worth a trial against
+<i>Pediculoides</i>.</p>
+
+<p>Various species of <b>Tyroglyphidæ</b> (<a href="#Fig_150">fig.&nbsp;150<i>f</i></a>) may abound on dried
+fruits and other products and attacking persons handling them, may
+cause a severe dermatitis, comparable to that described above for
+<i>Pediculoides ventricosus</i>. Many instances of their occurrence as such
+temporary ectoparasites are on record. Thus, workers who handle
+vanilla pods are subject to a severe dermatitis, known as vanillism,
+which is due to the attacks of <i>Tyroglyphus siro</i>, or a closely related
+species. The so-called "grocer's itch" is similarly caused by mites
+infesting various products. Castellani has shown that in Ceylon,
+workers employed in the copra mills, where dried cocoanut is ground
+up for export, are much annoyed by mites, which produce the so-called
+"copra itch." The skin of the hands, arms and legs, and sometimes
+of the whole body, except the face, is covered by fairly numerous, very
+pruriginous papules, often covered by small, bloody crusts due to
+scratching. The condition is readily mistaken for scabies. It is
+due to the attacks of <i>Tyroglyphus longior castellanii</i> which occur in
+enormous numbers in some samples of the copra.</p>
+
+
+<h3><a name="Sarcoptidae" id="Sarcoptidae"></a>Sarcoptidæ</h3>
+
+<p>The <b>Sarcoptidæ</b> are minute whitish mites, semi-globular in shape,
+with a delicate transversely striated cuticula. They lack eyes and
+tracheæ. The mouth-parts are fused at the base to form a cone
+which is usually designated as the head. The legs are short and
+stout, and composed of five segments. The tarsi may or may not
+possess a claw and may terminate in a pedunculated sucker, or simple
+long bristle, or both. The presence or absence of these structures<span class="pagenum"><a name="Page_73" id="Page_73">[Pg 73]</a></span>
+and their distribution are much used in classification. The mites
+live on or under the skin of mammals and birds, where they produce
+the disease known as scabies, mange, or
+itch. Several species of the Sarcoptidæ
+attack man but the most important of
+these, and the one pre-eminent as the
+"itch mite" is <i>Sarcoptes scabiei</i>.</p>
+
+<p>The female of <i>Sarcoptes scabiei</i>, of man,
+is oval and yellowish white; the male
+more rounded and of a somewhat reddish
+tinge, and much smaller. The body is
+marked by transverse striæ which are
+partly interrupted on the back. There
+are transverse rows of scales, or pointed
+spines, and scattered bristles on the
+dorsum.</p>
+
+<div class="figleft" style="width: 300px;"><a name="Fig_56a" id="Fig_56a"></a>
+<a href="images/f056a-full.png"><img src="images/f056a.png" width="300" height="427" alt="56a. Sarcoptes scabiei, male.
+(×100). After Fürstenberg." title="56a. Sarcoptes scabiei, male.
+(×100). After Fürstenberg." /></a>
+<span class="caption">56<i>a</i>. Sarcoptes scabiei, male.
+(×100). After Fürstenberg.</span>
+</div>
+
+<p>The male (<a href="#Fig_56a">fig.&nbsp;56</a>) which is from 200-240µ
+in length, and 150-200µ in breadth,
+possesses pedunculated suckers on each
+pair of legs except the third, which bears, instead, a long bristle.
+The female (<a href="#Fig_56b">fig.&nbsp;56</a>) 300-450µ in length and 250-350µ in breadth, has
+the pedunculated suckers on the first and second pairs of legs, only,
+the third and fourth terminating in bristles.</p>
+
+<div class="figright" style="width: 300px;"><a name="Fig_56b" id="Fig_56b"></a>
+<a href="images/f056b-full.png"><img src="images/f056b.png" width="300" height="416" alt="56b. Sarcoptes scabiei, female.
+(×100.) After Fürstenberg." title="56b. Sarcoptes scabiei, female.
+(×100.) After Fürstenberg." /></a>
+<span class="caption">56<i>b</i>. Sarcoptes scabiei, female.
+(×100.) After Fürstenberg.</span>
+</div>
+
+<p>The mite lives in irregular galleries from
+a few millimeters to several centimeters in
+length, which it excavates in the epidermis
+(<a href="#Fig_57">fig.&nbsp;57</a>). It works especially where the
+skin is thin, such as between the fingers,
+in the bend of the elbows and knees, and
+in the groin, but it is by no means restricted
+to these localities. The female, alone,
+tunnels into the skin; the males remain
+under the superficial epidermal scales, and
+seldom are found, as they die soon after
+mating.</p>
+
+<p>As she burrows into the skin the female
+deposits her eggs, which measure about
+150 × 100µ. Fürstenberg says that each
+deposits an average of twenty-two to twenty-four eggs, though
+Gudden reports a single burrow as containing fifty-one. From these<span class="pagenum"><a name="Page_74" id="Page_74">[Pg 74]</a></span>
+there develop after about seven days, the hexapod larvæ. These
+molt on the sixteenth day to form an octopod nymph, which molts
+again the twenty-first day. At the end of the fourth week the
+nymphs molt to form the sexually mature males and the so-called
+pubescent females. These pair, the males die, and the females again
+cast their skin, and become the oviparous females. Thus the life
+cycle is completed in about twenty-eight days.</p>
+
+<p>The external temperature exercises a great influence on the development
+of the mites and thus, during the winter, the areas of infestation
+not only do not spread, but they become restricted. As soon as
+the temperature rises, the mites increase and the infestation becomes
+much more extensive.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_57" id="Fig_57"></a>
+<a href="images/f057-full.png"><img src="images/f057.png" width="500" height="259" alt="57. Sarcoptes scabiei. Diagrammatic representation of the course in
+the skin of man." title="57. Sarcoptes scabiei. Diagrammatic representation of the course in
+the skin of man." /></a>
+<span class="caption">57. Sarcoptes scabiei. Diagrammatic representation of the course in
+the skin of man.</span>
+</div>
+
+<p>In considering the possible sources of infestation, and the chances
+of reinfestation after treatment, the question of the ability of the mite
+to live apart from its host is a very important one. Unfortunately
+there are few reliable data on this subject. Gerlach found that,
+exposed in the dry, warm air of a room they became very inactive
+within twenty-four hours, that after two days they showed only
+slight movement, and that after three or four days they could not
+be revived by moisture and warming. The important fact was
+brought out that in moist air, in folded soiled underwear, they survived
+as long as ten days. Bourguignon found that under the most
+favorable conditions the mites of <i>Sarcoptes scabiei equi</i> would live for
+sixteen days.</p>
+
+<p>The disease designated the "itch" or "scabies," in man has been
+known from time immemorial, but until within less than a hundred
+years it was almost universally attributed to malnutrition, errors of<span class="pagenum"><a name="Page_75" id="Page_75">[Pg 75]</a></span>
+diet, or "bad blood." This was in spite of the fact that the mite was
+known to Mouffet and that Bonomo had figured both the adult and
+the egg and had declared the mite the sole cause of the disease. In
+1834 the Corsican medical student, Francis Renucci, demonstrated
+the mite before a clinic in Saint Louis Hospital in Paris and soon
+thereafter there followed detailed studies of the life history of the
+various itch mites of
+man and animals.</p>
+
+<div class="figcenter" style="width: 270px;"><a name="Fig_58" id="Fig_58"></a>
+<a href="images/f058-full.png"><img src="images/f058.png" width="270" height="390" alt="58. Scabies on the hand. From portfolio of Dermochromes
+by permission of Rebman &amp; Co., of
+New York. Publishers." title="58. Scabies on the hand. From portfolio of Dermochromes
+by permission of Rebman &amp; Co., of
+New York. Publishers." /></a>
+<span class="caption">58. Scabies on the hand. From portfolio of Dermochromes
+by permission of Rebman&nbsp;&amp;&nbsp;Co., of
+New York. Publishers.</span>
+</div>
+
+<p>The disease is a cosmopolitan
+one, being exceedingly
+abundant in
+some localities. Its
+spread is much favored
+where large numbers of
+people are crowded together
+under insanitary
+conditions and hence it
+increases greatly during
+wars and is widely disseminated
+and abundant
+immediately afterwards.
+Though more commonly
+to be met with among
+the lower classes, it not
+infrequently appears
+among those of the most
+cleanly, careful habits,
+and it is such cases that
+are most liable to wrong
+diagnosis by the physician.</p>
+
+<p>Infection occurs solely through the passage, direct or indirect,
+of the young fertilized females to the skin of a healthy individual.
+The adult, oviparous females do not quit their galleries and hence
+do not serve to spread the disease. The young females move about
+more or less at night and thus the principal source of infestation is
+through sleeping in the same bed with an infested person, or indirectly
+through bedclothes, or even towels or clothing. Diurnal infestation
+through contact or clothing is exceptional. Many cases are known
+of the disease being contracted from animals suffering from scabies,
+or mange.<span class="pagenum"><a name="Page_76" id="Page_76">[Pg 76]</a></span></p>
+
+<p>When a person is exposed to infestation, the trouble manifests
+itself after eight or ten days, though there usually elapses a period of
+twenty to thirty days before
+there is a suspicion of
+anything serious. The first
+symptom is an intense
+itching which increases
+when the patient is in bed.
+When the point of irritation
+is examined the galleries
+may usually be seen
+as characteristic sinuous
+lines, at first whitish in
+color but soon becoming
+blackish because of the contained
+eggs and excrement.
+The galleries, which may
+not be very distinct in
+some cases, may measure
+as much as four centimeters
+in length. Little
+vesicles, of the size of a
+pin head are produced by
+the secretions of the feeding mite; they are firm, and projecting, and
+contain a limpid fluid. Figures&nbsp;<a href="#Fig_58">58</a>
+and&nbsp;<a href="#Fig_59">59</a> show the typical appearance
+of scabies on the hands, while <a href="#Fig_60">figure&nbsp;60</a>
+shows a severe general infestation.
+The intolerable itching induces
+scratching and through this various
+complications may arise. The lesions
+are not normally found on the face
+and scalp, and are rare on the back.</p>
+
+<div class="figcenter" style="width: 315px;"><a name="Fig_59" id="Fig_59"></a>
+<a href="images/f059-full.png"><img src="images/f059.png" width="315" height="396" alt="59. Scabies on the hand. After Duhring." title="59. Scabies on the hand. After Duhring." /></a>
+<span class="caption">59. Scabies on the hand. After Duhring.</span>
+</div>
+
+<div class="figcenter" style="width: 315px;"><a name="Fig_60" id="Fig_60"></a>
+<a href="images/f060-full.png"><img src="images/f060.png" width="315" height="391" alt="60. Generalized infection of Scabies.
+After Morrow." title="60. Generalized infection of Scabies.
+After Morrow." /></a>
+<span class="caption">60. Generalized infection of Scabies.
+After Morrow.</span>
+</div>
+
+<p>Formerly, scabies was considered
+a very serious disease, for its cause
+and method of treatment were unknown,
+and potentially it may continue
+indefinitely. Generation after
+generation of the mites may develop
+and finally their number become so<span class="pagenum"><a name="Page_77" id="Page_77">[Pg 77]</a></span>
+great that the general health of the individual is seriously affected.
+Now that the true cause of the disease is known, it is easily controlled.</p>
+
+<p>Treatment usually consists in softening the skin by friction with
+soap and warm water, followed by a warm bath, and then applying
+some substance to kill the mites. Stiles gives the following directions,
+modified from Bourguignon's, as "a rather radical guide, to
+be modified according to facilities and according to the delicacy of the
+skin or condition of the patient":</p>
+
+<p>1. The patient, stripped naked, is energetically rubbed all over
+(except the head) for twenty minutes, with green soap and warm
+water. 2. He is then placed in a warm bath for thirty minutes,
+during which time the rubbing is continued. 3. The parasiticide
+is next rubbed in for twenty minutes and is allowed to remain on the
+body for four or five hours; in the meantime the patient's clothes are
+sterilized, to kill the eggs or mites attached to them. 4. A final
+bath is taken to remove the parasiticide.</p>
+
+<p>The parasiticide usually relied on is the officinal sulphur ointment
+of the United States pharmacop&oelig;ia. When infestation is severe it
+is necessary to repeat treatment after three or four days in order
+to kill mites which have hatched from the eggs.</p>
+
+<p>The above treatment is too severe for some individuals and may,
+of itself, produce a troublesome dermatitis. We have seen cases
+where the treatment was persisted in and aggravated the condition
+because it was supposed to be due to the parasite. For delicate-skinned
+patients the use of balsam of Peru is very satisfactory,
+and usually causes no irritation whatever. Of course, sources
+of reinfection should be carefully guarded against.</p>
+
+<p><i>Sarcoptes scabiei crustosæ</i>, which is a distinct variety, if not species,
+of the human itch mite, is the cause of so-called Norwegian itch.
+This disease is very contagious, and is much more resistant than the
+ordinary scabies. Unlike the latter, it may occur on the face and
+scalp.</p>
+
+<p><i>Sarcoptes scabiei</i> not only attacks man but also occurs on a large
+number of mammals. Many species, based on choice of host, and
+minute differences in size and secondary characters, have been
+established, but most students of the subject relegate these to
+varietal rank. Many of them readily attack man, but they have
+become sufficiently adapted to their normal host so that they are
+usually less persistent on man.<span class="pagenum"><a name="Page_78" id="Page_78">[Pg 78]</a></span></p>
+
+<p><i>Notoedres cati</i> (usually known as <i>Sarcoptes minor</i>) is a species
+of itch mites which produce an often fatal disease of cats. The body
+is rounded and it is considerably smaller than <i>Sarcoptes scabiei</i>,
+the female (<a href="#Fig_61">fig.&nbsp;61</a>) measuring 215-230µ long and 165-175µ wide;
+the males 145-150µ by 120-125µ. The most important character
+separating <i>Notoedres</i> from <i>Sarcoptes</i> is the position of the anus,
+which is dorsal instead of terminal. The mite readily transfers
+to man but does not persist, the infestation usually disappearing
+spontaneously in about two weeks. Infested cats are
+very difficult to cure, unless treatment is begun at
+the very inception of the outbreak, and under ordinary
+circumstances it is better to kill them promptly,
+to avoid spread of the disease to children and others
+who may be exposed.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_61" id="Fig_61"></a>
+<a href="images/f061-full.png"><img src="images/f061.png" width="500" height="312" alt="61. Notoedres cati, male and female. After Railliet." title="61. Not&oelig;dres cati, male and female. After Railliet." /></a>
+<span class="caption">61. Not&oelig;dres cati, male and female. After Railliet.</span>
+</div>
+
+
+<h3><a name="Demodecidae" id="Demodecidae"></a>Demodecidæ</h3>
+
+<div class="figcenter" style="width: 125px;"><a name="Fig_62" id="Fig_62"></a>
+<a href="images/f062-full.png"><img src="images/f062.png" width="125" height="463" alt="62. Demodex folliculorum.
+(×200).
+After Blanchard." title="62. Demodex folliculorum.
+(×200).
+After Blanchard." /></a>
+<span class="caption">62. Demodex folliculorum.
+(×200).
+After Blanchard.</span>
+</div>
+
+<p>The <b>Demodecidæ</b> are small, elongate, vermiform
+mites which live in the hair follicles of mammals.
+The family characteristics will be brought out in the
+discussion of the species infesting man, <i>Demodex
+folliculorum</i>.</p>
+
+<p><i>Demodex folliculorum</i> (<a href="#Fig_62">fig.&nbsp;62</a>) is to be found very
+commonly in the hair follicles and sebaceous glands
+of man. It is vermiform in appearance, and with the
+elongate abdomen transversely striated so as to give
+it the appearance of segmentation. The female is 380-400µ
+long by 45µ; the male 300µ by 40µ. The three-jointed<span class="pagenum"><a name="Page_79" id="Page_79">[Pg 79]</a></span>
+legs, eight in number, are reduced to mere stubs in the adult.
+The larval form is hexopod. These mites thus show in their form a
+striking adaptation to their environment. In the sebaceous glands
+and hair follicles they lie with their heads down (<a href="#Fig_63">fig.&nbsp;63</a>). Usually
+there are only a few in a gland, but Gruby has counted as many as
+two hundred.</p>
+
+<div class="figcenter" style="width: 250px;"><a name="Fig_63" id="Fig_63"></a>
+<a href="images/f063-full.png"><img src="images/f063.png" width="250" height="378" alt="63. Demodex folliculorum. Section through skin showing the
+mites in situ. Magnification of Nos. 1, 2, 6 and 7, ×150;
+Nos, 3, 4, 5, ×450. After Megnin." title="63. Demodex folliculorum. Section through skin showing the
+mites in situ. Magnification of Nos. 1, 2, 6 and 7, ×150;
+Nos, 3, 4, 5, ×450. After Megnin." /></a>
+<span class="caption">63. Demodex folliculorum. Section through skin showing the
+mites in situ. Magnification of Nos. 1, 2, 6 and 7, ×150;
+Nos, 3, 4, 5, ×450. After Megnin.</span>
+</div>
+
+<p>The frequency with which they occur in man is surprising. According
+to European statistics they are found in 50 per cent to 60 per
+cent or even more. Gruby found them in forty out of sixty persons<span class="pagenum"><a name="Page_80" id="Page_80">[Pg 80]</a></span>
+examined. These figures are very commonly quoted, but reliable
+data for the United States seem to be lacking. Our studies indicate
+that it is very much less common in this country than is generally
+assumed.</p>
+
+<p>The Demodex in man does not, as a rule, cause the slightest
+inconvenience to its host. It is often stated that they give rise to
+comedons or "black-heads" but there is no clear evidence that they
+are ever implicated. Certain it is that they are not the usual cause.
+A variety of the same, or a very closely related species of <i>Demodex</i>,
+on the dog gives rise to the very resistant and often fatal follicular
+mange.</p>
+
+
+<h3><a name="Hexapoda_or_True_Insects" id="Hexapoda_or_True_Insects"></a><span class="smcap">Hexapoda or True Insects</span></h3>
+
+<p>The <b>Hexapoda</b>, or true insects, are characterized by the fact that
+the adult possesses three pairs of legs. The body is distinctly
+segmented and is divided into head, thorax, and abdomen.</p>
+
+<p>The mouth-parts in a generalized form, consist of an upper lip,
+or <i>labrum</i>, which is a part of the head capsule, and a central unpaired
+<i>hypopharynx</i>, two <i>mandibles</i>, two <i>maxillæ</i> and a lower lip, or <i>labium</i>,
+made up of the fused pair of second maxillæ. These parts may be
+greatly modified, dependent upon whether they are used for biting,
+sucking, piercing and sucking, or a combination of biting and sucking.</p>
+
+<p>Roughly speaking, insects may be grouped into those which
+undergo <i>complete metamorphosis</i> and those which have <i>incomplete
+metamorphosis</i>. They are said to undergo complete metamorphosis
+when the young form, as it leaves the egg, bears no resemblance to
+the adult. For example, the maggot changes to a quiescent pupa
+and from this emerges the winged active fly. They undergo incomplete
+metamorphosis, when the young insect, as it leaves the egg,
+resembles the adult to a greater or less extent, and after undergoing
+a certain number of molts becomes sexually mature.</p>
+
+<p>Representatives of several orders have been reported as accidental
+or faculative parasites of man, but the true parasites are restricted
+to four orders. These are the Siphunculata; the Hemiptera, the
+Diptera and the Siphonaptera.</p>
+
+
+<h3><a name="Siphunculata" id="Siphunculata"></a><span class="smcap">Siphunculata</span></h3>
+
+<p>The order <b>Siphunculata</b> was established by Meinert to include the
+true sucking lice. These are small wingless insects, with reduced
+mouth-parts, adapted for sucking; thorax apparently a single piece
+due to indistinct separation of its three segments: the compound eyes<span class="pagenum"><a name="Page_81" id="Page_81">[Pg 81]</a></span>
+reduced to a single ommatidium on each side. The short, powerful
+legs are terminated by a single long claw. Metamorphosis incomplete.</p>
+
+<p>There has been a great deal of discussion regarding the structure
+of the mouth-parts, and the relationships of the sucking lice, and the
+questions cannot yet be regarded
+as settled. The conflicting
+views are well represented
+by Cholodkovsky
+(1904 and 1905) and by
+Enderlein (1904).</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_64" id="Fig_64"></a>
+<a href="images/f064-full.png"><img src="images/f064.png" width="450" height="252" alt="64. Pediculus showing the blind sac (b) containing the
+mouth parts (a) beneath the alimentary canal
+(p). After Pawlowsky." title="64. Pediculus showing the blind sac (b) containing the
+mouth parts (a) beneath the alimentary canal
+(p). After Pawlowsky." /></a>
+<span class="caption">64. Pediculus showing the blind sac&nbsp;(<i>b</i>) containing the
+mouth parts&nbsp;(<i>a</i>) beneath the alimentary canal&nbsp;(<i>p</i>).
+After Pawlowsky.</span>
+</div>
+
+<p>Following Graber, it is
+generally stated that the
+mouth-parts consist of a
+short tube furnished with
+hooks in front, which constitutes
+the lower lip, and that within this is a delicate sucking tube
+derived from the fusion of the labrum and the mandibles. Opposed
+to this, Cholodkovsky and, more recently, Pawlowsky, (1906), have
+shown that the piercing apparatus lies in a blind sac under the
+pharynx and opening into the mouth cavity (<a href="#Fig_64">fig.&nbsp;64</a>). It does not
+form a true tube but a furrow with its open surface uppermost.
+Eysell has shown that, in addition, there is a pair of chitinous rods
+which he regards as the homologues of the maxillæ.</p>
+
+<p>When the louse feeds, it everts the anterior part of the mouth
+cavity, with its circle of hooks. The latter serve for anchoring
+the bug, and the piercing apparatus is then pushed
+out.</p>
+
+<div class="figright" style="width: 150px;"><a name="Fig_65" id="Fig_65"></a>
+<a href="images/f065-full.png"><img src="images/f065.png" width="150" height="275" alt="65. Pediculus humanus,
+ventral aspect
+of male. (×10)" title="65. Pediculus humanus,
+ventral aspect
+of male. (×10)" /></a>
+<span class="caption">65. Pediculus humanus,
+ventral aspect
+of male. (×10)</span>
+</div>
+
+<p>Most writers have classed the sucking lice as a
+sub-order of the Hemiptera, but the more recent
+anatomical and developmental studies render this
+grouping untenable. An important fact, bearing on
+the question, is that, as shown by Gross, (1905),
+the structure of the ovaries is radically different
+from that of the Hemiptera.</p>
+
+<p>Lice infestation and its effects are known medically
+as <i>pediculosis</i>. Though their continued presence
+is the result of the grossest neglect and filthiness, the original
+infestation may be innocently obtained and by people of the most
+careful habits.<span class="pagenum"><a name="Page_82" id="Page_82">[Pg 82]</a></span></p>
+
+<p>Three species commonly attack man. Strangely enough, there
+are very few accurate data regarding their life history.</p>
+
+<p><i>Pediculus humanus</i> (<a href="#Fig_65">fig.&nbsp;65</a>), the head louse, is the most widely
+distributed. It is usually referred to in medical literature as <i>Pediculus
+capitis</i>, but the Linnean specific name has priority. In color
+it is of a pale gray, blackish on the margins. It is claimed by some
+authors that the color varies according to the color of the skin of the
+host. The abdomen is
+composed of seven distinct
+segments, bearing
+spiracles laterally.
+There is considerable
+variation in size. The
+males average 1.8 mm.
+and the females 2.7 mm.
+in length.</p>
+
+<p>The eggs, fifty to
+sixty in number, stick
+firmly to the hairs of
+the host and are known
+as nits. They are large
+and conspicuous, especially
+on dark hair and
+are provided with an
+operculum, or cap, at
+the free end, where the
+nymphs emerge. They
+hatch in about six days
+and about the eighteenth
+day the young
+lice are sexually mature.</p>
+
+<div class="figcenter" style="width: 300px;"><a name="Fig_66" id="Fig_66"></a>
+<a href="images/f066-full.png"><img src="images/f066.png" width="300" height="353" alt="66. Pediculosis of the head. The illustration shows the
+characteristic indications of the presence of lice, viz:
+the occipital eczema gluing the hairs together, the
+swollen cervical glands, and the porrigo, or eruption
+of contagious pustules upon the neck. After
+Fox." title="66. Pediculosis of the head. The illustration shows the
+characteristic indications of the presence of lice, viz:
+the occipital eczema gluing the hairs together, the
+swollen cervical glands, and the porrigo, or eruption
+of contagious pustules upon the neck. After
+Fox." /></a>
+<span class="caption">66. Pediculosis of the head. The illustration shows the
+characteristic indications of the presence of lice, viz:
+the occipital eczema gluing the hairs together, the
+swollen cervical glands, and the porrigo, or eruption
+of contagious pustules upon the neck. After
+Fox.</span>
+</div>
+
+<p>The head lice live by preference on the scalp of their host but
+occasionally they are found on the eyelashes and beard, or in the
+pubic region. They may also occur elsewhere on the body. The
+penetration of the rostrum into the skin and the discharge of an irritating
+saliva produce a severe itching, accompanied by the formation
+of an eczema-like eruption (<a href="#Fig_66">fig.&nbsp;66</a>). When the infestation is severe,
+the discharge from the pustules mats down the hair, and scabs are
+formed, under which the insects swarm. "If allowed to run, a regular
+carapace may form, called <i>trichoma</i>, and the head exudes a f&oelig;tid<span class="pagenum"><a name="Page_83" id="Page_83">[Pg 83]</a></span>
+odor. Various low plants may grow in the trichoma, the whole
+being known as <i>plica palonica</i>."&mdash;Stiles.</p>
+
+<p>Sources of infestation are various. School children may obtain
+the lice from seatmates, by wearing the hats or caps of infested mates,
+or by the use, in common, of brushes and combs. They may be
+obtained from infested beds or sleeper berths. Stiles reports an instance
+in which a large number of girls in a fashionable boarding
+school developed lousiness a short time after traveling in a sleeping
+car.</p>
+
+<p>Treatment is simple, for the parasites may readily be controlled
+by cleanliness and washing the head with a two per cent solution of
+carbolic acid or even kerosene. The latter is better used mixed with
+equal parts of olive oil, to avoid irritation. The treatment should
+be applied at night and followed the next morning by a shampoo with
+soap and warm water. It is necessary to repeat the operation in a
+few days. Xylol, used pure, or with the addition of five per cent
+of vaseline, is also very efficacious. Of course, the patient must be
+cautioned to stay away from a lighted lamp or fire while using either
+the kerosene or xylol. While these treatments will kill the eggs or
+nits, they will not remove them from the hairs. Pusey recommends
+repeated washings with vinegar or 25 per cent of acetic acid in water,
+for the purpose of loosening and removing the nits.</p>
+
+<p>Treatment of severe infestations in females is often troublesome
+on account of long hair. For such cases the following method recommended
+by Whitfield (1912) is especially applicable:</p>
+
+<p>The patient is laid on her back on the bed with her head over the
+edge, and beneath the head is placed a basin on a chair so that the
+hair lies in the basin. A solution of 1 in 40 carbolic acid is then poured
+over the hair into the basin and sluiced backwards and forwards
+until the whole of the hair is thoroughly soaked with it. It is especially
+necessary that care should be taken to secure thorough saturation
+of the hair over the ears and at the nape of the neck, since these
+parts are not only the sites of predilection of the parasites but they
+are apt to escape the solution. This sluicing is carried out for ten
+minutes by the clock. At the end of ten minutes the hair is lifted
+from the basin and allowed to drain, but is not dried or even thoroughly
+wrung out. The whole head is then swathed with a thick
+towel or better, a large piece of common house flannel, which is
+fastened up to form a sort of turban, and is allowed to remain thus
+for an hour. It can then be washed or simply allowed to dry, as the<span class="pagenum"><a name="Page_84" id="Page_84">[Pg 84]</a></span>
+carbolic quickly disperses. At the end of this period every pediculus
+and what is better, every ovum is dead and no relapse will occur
+unless there is exposure to fresh contagion. Whitfield states that
+there seem to be no disadvantages in this method, which he has used
+for years. He has never seen carboluria result from it, but would
+advise first cutting the hair of children under five years of age.</p>
+
+<p><i>Pediculus corporis</i> (= <i>P. vestimenti</i>) the body louse, is larger than
+the preceding species, the female measuring 3.3 mm., and the male
+3 mm. in length. The color is a dirty white, or grayish. <i>P. corporis</i>
+has been regarded by some authorities as merely a variety of <i>P.
+humanus</i> but Piaget maintains there are good characters separating
+the two species.</p>
+
+<p>The body louse lives in the folds and seams of the clothing of its
+host, passing to the skin only when it wishes to feed. Brumpt
+states that he has found enormous numbers of them in the collars
+of glass-ware or grains worn by certain naked tribes in Africa.</p>
+
+<p>Exact data regarding the life-history of this species have been
+supplied, in part, by the work of Warburton (1910), cited by Nuttall.
+He found that <i>Pediculus corporis</i> lives longer than <i>P. humanus</i> under
+adverse conditions. This is doubtless due to its living habitually
+on the clothing, whereas <i>humanus</i> lives upon the head, where it has
+more frequent opportunities of feeding. He reared a single female
+upon his own person, keeping the louse enclosed in a cotton-plugged
+tube with a particle of cloth to which it could cling. The tube was
+kept next to his body, thus simulating the natural conditions of
+warmth and moisture under which the lice thrive. The specimen
+was fed twice daily, while it clung to the cloth upon which it rested.
+Under these conditions she lived for one month. Copulation commenced
+five days after the female had hatched and was repeated a
+number of times, sexual union lasting for hours. The female laid
+one hundred and twenty-four eggs within twenty-five days.</p>
+
+<p>The eggs hatched after eight days, under favorable conditions,
+such as those under which the female was kept. They did not
+hatch in the cold. Eggs kept near the person during the day and
+hung in clothing by the bedside at night, during the winter, in a cold
+room, did not hatch until the thirty-fifth day. When the nymphs
+emerge from the eggs, they feed at once, if given a chance to do so.
+They are prone to scatter about the person and abandon the fragment
+of cloth to which the adult clings.<span class="pagenum"><a name="Page_85" id="Page_85">[Pg 85]</a></span></p>
+
+<p>The adult stage is reached on the eleventh day, after three molts,
+about four days apart. Adults enter into copulation about the
+fifth day and as the eggs require eight days for development,
+the total cycle, under favorable conditions, is about twenty-four
+days. Warburton's data differ considerably from those commonly
+quoted and serve to emphasize the necessity for detailed studies
+of some of the commonest of parasitic insects.</p>
+
+<p>Body lice are voracious feeders, producing by their bites and the
+irritating saliva which they inject, rosy elevations and papules which
+become covered with a brownish
+crust. The intense itching provokes
+scratching, and characteristic
+white scars (<a href="#Fig_67">fig.&nbsp;67</a>) surrounded
+by brownish pigment
+(<a href="#Fig_68">fig.&nbsp;68</a>) are formed. The skin
+may become thickened and take
+on a bronze tinge. This melanoderma
+is especially marked
+in the region between the shoulders
+but it may become generalized,
+a prominent characteristic
+of "vagabond's disease." According
+to Dubre and Beille,
+this melanoderma is due to a
+toxic substance secreted by the
+lice, which indirectly provokes
+the formation of pigment.</p>
+
+<div class="figcenter" style="width: 300px;"><a name="Fig_67" id="Fig_67"></a>
+<a href="images/f067-full.png"><img src="images/f067.png" width="300" height="391" alt="67. Pediculosis in man caused by the body
+louse. After Morrow." title="67. Pediculosis in man caused by the body
+louse. After Morrow." /></a>
+<span class="caption">67. Pediculosis in man caused by the body
+louse. After Morrow.</span>
+</div>
+
+<p>Control measures, in the case
+of the body louse, consist in
+boiling or steaming the clothes or in some cases, sterilizing by dry heat.
+The dermatitis may be relieved by the use of zinc-oxide ointment,
+to which Pusey recommends that there be added, on account of their
+parasiticidal properties, sulphur and balsam of Peru, equal parts, 15
+to 30 grains to the ounce.</p>
+
+<div class="figcenter" style="width: 245px;"><a name="Fig_68" id="Fig_68"></a>
+<a href="images/f068-full.png"><img src="images/f068.png" width="245" height="463" alt="68. Melanoderma caused by the body
+louse. From Portfolio of Dermochromes,
+by permission of Rebman
+&amp; Co., New York, Publishers." title="68. Melanoderma caused by the body
+louse. From Portfolio of Dermochromes,
+by permission of Rebman
+&amp; Co., New York, Publishers." /></a>
+<span class="caption">68. Melanoderma caused by the body
+louse. From Portfolio of Dermochromes,
+by permission of Rebman
+&amp; Co., New York, Publishers.</span>
+</div>
+
+<div class="figright" style="width: 200px;"><a name="Fig_69" id="Fig_69"></a>
+<a href="images/f069-full.png"><img src="images/f069.png" width="200" height="182" alt="69. Phthirius pubis. Ventral
+aspect of female.
+(×12)." title="69. Phthirius pubis. Ventral
+aspect of female.
+(×12)." /></a>
+<span class="caption">69. Phthirius pubis. Ventral
+aspect of female.
+(×12).</span>
+</div>
+
+<p><i>Phthirius pubis</i> (=&nbsp;<i>P. inguinalis</i>), the pubic louse, or so-called
+"crab louse," differs greatly from the preceding in appearance. It is
+characterized by its relatively short head which fits into a broad
+depression in the thorax. The latter is broad and flat and merges
+into the abdomen. The first pair of legs is slender and terminated
+by a straight claw. The second and third pairs of legs are thicker<span class="pagenum"><a name="Page_86" id="Page_86">[Pg 86]</a></span>
+and are provided with powerful claws fitted for clinging to hairs.
+The females (<a href="#Fig_69">fig.&nbsp;69</a>) measure 1.5 to 2 mm. in length by 1.5 mm. in
+breadth. The male averages a
+little over half as large. The eggs,
+or nits, are fixed at the base of the
+hairs. Only a few, ten to fifteen
+are deposited by a single female,
+and they hatch in about a week's
+time. The young lice mature in
+two weeks.</p>
+
+<p>The pubic louse usually infests
+the hairs of the pubis and the
+perineal region. It may pass to
+the arm pits or even to the beard
+or moustache. Rarely, it occurs
+on the eyelids, and it has even
+been found, in a very few instances,
+occurring in all stages, on the scalp.
+Infestation may be contracted
+from beds or even from badly infested
+persons in a crowd. We
+have seen several cases which undoubtedly
+were due to the use of
+public water closets. It produces
+papular eruption and an intense
+pruritis. When abundant, there
+occurs a grayish discoloration of
+the skin which Duguet has shown
+is due to a poisonous saliva injected by the louse,
+as is the melanoderma caused by the body louse.</p>
+
+<p>The pubic louse may be exterminated by the
+measures recommended for the head louse, or
+by the use of officinal mercurial ointment.</p>
+
+
+<h3><span class="smcap">Hemiptera</span></h3>
+
+<p>Several species of <b>Hemiptera-Heteroptera</b> are
+habitual parasites of man, and others occur
+as occasional or accidental parasites. Of all
+these, the most important and widespread are the bed-bugs, belonging
+to the genus <i>Cimex</i> (= <i>Acanthia</i>).<span class="pagenum"><a name="Page_87" id="Page_87">[Pg 87]</a></span></p>
+
+
+<p><a name="The_Bed-bugs" id="The_Bed-bugs"></a><b>The Bed-bugs</b>&mdash;The bed-bugs are characterized by a much flattened
+oval body, with the short, broad head unconstricted behind,
+and fitting into the strongly excavated anterior margin of the thorax.
+The compound eyes are prominent, simple eyes lacking. Antennæ
+four-jointed, the first segment short, the second long and thick, and
+the third and fourth slender. The tarsi are short and three segmented.</p>
+
+<p>It is often assumed in the literature of the subject that there is
+but a single species of <i>Cimex</i> attacking man, but several such species
+are to be recognized. These are distinguishable by the characters
+given in Chapter XII. We shall consider
+especially <i>Cimex lectularius</i>, the
+most common and widespread species.</p>
+
+<p><i>Cimex lectularius</i> (= <i>Acanthia
+lectularia</i>, <i>Clinocoris lectularius</i>), is
+one of the most cosmopolitan of human
+parasites but, like the lice, it has been
+comparatively little studied until
+recent years, when the possibility
+that it may be concerned with the
+transmission of various diseases has
+awakened interest in the details of
+its life-history and habits.</p>
+
+<div class="figleft" style="width: 350px;"><a name="Fig_70" id="Fig_70"></a>
+<a href="images/f070-full.png"><img src="images/f070.png" width="350" height="382" alt="70. Cimex lectularius adult and eggs.
+Photograph by M. V. S." title="70. Cimex lectularius adult and eggs.
+Photograph by M. V. S." /></a>
+<span class="caption">70. Cimex lectularius adult and eggs.
+Photograph by M.&nbsp;V.&nbsp;S.</span>
+</div>
+
+<p>The adult insect (<a href="#Fig_70">fig.&nbsp;70</a>) is 4-5
+mm. long by 3 mm. broad, reddish
+brown in color, with the beak and body appendages lighter in color.
+The short, broad and somewhat rectangular head has no neck-like
+constriction but fits into the broadly semilunar prothorax. The
+four segmented labium or proboscis encloses the lancet-like maxillæ
+and mandibles. The distal of the four antennal segments is slightly
+club-shaped. The prothorax is characteristic of the species, being
+deeply incised anteriorly and with its thin lateral margins somewhat
+turned up. The mesothorax is triangular, with the apex posteriorly,
+and bears the greatly atrophied first pair of wings. There is no trace
+of the metathoracic pair. The greatly flattened abdomen has eight
+visible segments, though in reality the first is greatly reduced and
+has been disregarded by most writers. The body is densely covered
+with short bristles and hairs, the former being peculiarly saber-shaped
+structures sharply toothed at the apex and along the convex
+side (<a href="#Fig_159">fig.&nbsp;159<i>b</i></a>).<span class="pagenum"><a name="Page_88" id="Page_88">[Pg 88]</a></span></p>
+
+<p>The peculiar disagreeable odor of the adult bed-bug is due to the
+secretion of the stink glands which lie on the inner surface of the
+mesosternum and open by a pair of orifices in front of the metacoxæ,
+near the middle line. In the nymphs, the thoracic glands are not
+developed but in the abdomen there are to be found three unpaired
+dorsal stink glands, which persist until the fifth molt, when they
+become atrophied and replaced by the thoracic glands. The nymphal
+glands occupy the median dorsal portion of the abdomen, opening
+by paired pores at the anterior margin of the fourth, fifth and sixth
+segments. The secretion is a clear, oily, volatile fluid, strongly acid
+in reaction. Similar glands are to be found in most of the Hemiptera-Heteroptera
+and their secretion is doubtless protective, through
+being disagreeable to the birds. In the bed-bug, as Marlatt points
+out, "it is probably an illustration of a very common phenomenon
+among animals, i.e., the persistence of a characteristic which is no
+longer of any special value to the possessor." In fact, its possession
+is a distinct disadvantage to the bed-bug, as the odor frequently
+reveals the presence of the bugs, before they are seen.</p>
+
+<p>The eggs of the bed-bug (<a href="#Fig_70">fig.&nbsp;70</a>) are pearly white, oval in outline,
+about a millimeter long, and possess a small operculum or cap
+at one end, which is pushed off when the young hatches. They are
+laid intermittently, for a long period, in cracks and crevices of beds
+and furniture, under seams of mattresses, under loose wall paper,
+and similar places of concealment of the adult bugs. Girault (1905)
+observed a well-fed female deposit one hundred and eleven eggs
+during the sixty-one days that she was kept in captivity. She had
+apparently deposited some of her eggs before being captured.</p>
+
+<p>The eggs hatch in six to ten days, the newly emerged nymphs
+being about 1.5 mm. in length and of a pale yellowish white color.
+They grow slowly, molting five times. At the last molt the mesathoracic
+wing pads appear, characteristic of the adult. The total
+length of the nymphal stage varies greatly, depending upon conditions
+of food supply, temperature and possibly other factors. Marlatt
+(1907) found under most favorable conditions a period averaging
+eight days between molting which, added to an equal egg period,
+gave a total of about seven weeks from egg to adult insect. Girault
+(1912) found the postembryonic period as low as twenty-nine days
+and as high as seventy days under apparently similar and normal
+conditions of food supply. Under optimum and normal conditions
+of food supply, beginning August 27, the average nymphal life was<span class="pagenum"><a name="Page_89" id="Page_89">[Pg 89]</a></span>
+69.9 days; average number of meals 8.75 and the molts 5. Under
+conditions allowing about half the normal food supply the average
+nymphal life was from 116.9 to 139 days. Nymphs starved from
+birth lived up to 42 days. We have kept unfed nymphs, of the first
+stage, alive in a bottle for 75 days. The interesting fact was brought
+out that under these conditions of minimum food supply there were
+sometimes six molts instead of the normal number.</p>
+
+<p>The adults are remarkable for their longevity, a factor which is
+of importance in considering the spread of the insect and methods of
+control. Dufour (1833) (not De Geer, as often stated) kept specimens
+for a year, in a closed vial, without food. This ability, coupled
+with their willingness to feed upon mice, bats, and other small mammals,
+and even upon birds, accounts for the long periods that deserted
+houses and camps may remain infested. There is no evidence that
+under such conditions they are able to subsist on the starch of the
+wall paper, juices of moistened wood, or the moisture in the accumulations
+of dust, as is often stated.</p>
+
+<p>There are three or four generations a year, as Girault's breeding
+experiments have conclusively shown. He found that the bed-bug
+does not hibernate where the conditions are such as to allow it to
+breed and that breeding is continuous unless interrupted by the lack
+of food or, during the winter, by low temperature.</p>
+
+<p>Bed-bugs ordinarily crawl from their hiding places and attack
+the face and neck or uncovered parts of the legs and arms of their
+victims. If undisturbed, they will feed to repletion. We have
+found that the young nymph would glut itself in about six minutes,
+though some individuals fed continuously for nine minutes, while
+the adult required ten to fifteen minutes for a full meal. When
+gorged, it quickly retreats to a crack or crevice to digest its meal,
+a process which requires two or three days. The effect of the bite
+depends very greatly on the susceptibility of the individual attacked.
+Some persons are so little affected that they may be wholly ignorant
+of the presence of a large number of bugs. Usually the bite produces
+a small hard swelling, or wheal, whitish in color. It may even be
+accompanied by an edema and a disagreeable inflammation, and in
+such susceptible individuals the restlessness and loss of sleep due to
+the presence of the insects may be a matter of considerable importance.
+Stiles (1907) records the case of a young man who underwent
+treatment for neurasthenia, the diagnosis being agreed upon by
+several prominent physicians; all symptoms promptly disappeared,<span class="pagenum"><a name="Page_90" id="Page_90">[Pg 90]</a></span>
+however, immediately following a thorough fumigation of his rooms,
+where nearly a pint of bed-bugs were collected.</p>
+
+<p>It is natural to suppose that an insect which throughout its whole
+life is in such intimate relationship with man should play an important
+rôle in the transmission of disease. Yet comparatively little is
+definitely known regarding the importance of the bed-bug in this
+respect. It has been shown that it is capable of transmitting the
+bubonic plague, and South American trypanosomiasis. Nuttall
+succeeded in transmitting European relapsing fever from mouse to
+mouse by its bite. It has been claimed that Oriental sore, tuberculosis,
+and even syphilis may be so carried. These phases of the
+subject will be considered later.</p>
+
+<p>The sources of infestation are many, and the invasion of a house
+is not necessarily due to neglect, though the continued presence of
+the pests is quite another matter. In apartments and closely placed
+houses they are known to invade new quarters by migration. They
+are frequently to be met with in boat and sleeper berths, and even
+the plush seats of day coaches, whence a nucleus may be carried in
+baggage to residences. They may be brought in the laundry or
+in clothes of servants.</p>
+
+<p>Usually they are a great scourge in frontier settlements and it is
+generally believed that they live in nature under the bark of trees,
+in lumber, and under similar conditions. This belief is founded upon
+the common occurrence of bugs resembling the bed-bug, in such
+places. As a matter of fact, they are no relation to bed-bugs but
+belong to plant-feeding forms alone (<a href="#Fig_19">fig.&nbsp;19</a> <i>c</i>,&nbsp;<i>d</i>).</p>
+
+<p>It is also often stated that bed-bugs live in poultry houses, in
+swallows nests, and on bats, and that it is from these sources that they
+gain access to dwellings. These bugs are specifically distinct from
+the true bed-bug, but any of them may, rarely, invade houses.
+Moreover, chicken houses are sometimes thoroughly infested with
+the true <i>Cimex lectularius</i>.</p>
+
+<p>Control measures consist in the use of iron bedsteads and the
+reduction of hiding places for the bugs. If the infestation is slight
+they may be exterminated by a vigilant and systematic hunt, and
+by squirting gasoline or alcohol into cracks and crevices of the beds,
+and furniture. Fumigation must be resorted to in more general
+infestations.</p>
+
+<p>The simplest and safest method of fumigation is by the use of
+flowers of sulphur at the rate of two pounds to each one thousand<span class="pagenum"><a name="Page_91" id="Page_91">[Pg 91]</a></span>
+cubic feet of room space. The sulphur should be placed in a pan,
+a well made in the top of the pile and a little alcohol poured in, to
+facilitate burning. The whole should be placed in a larger pan
+and surrounded by water so as to avoid all danger of fire. Windows
+should be tightly closed, beds, closets and drawers opened, and
+bedding spread out over chairs in order to expose them fully to the
+fumes. As metal is tarnished by the sulphur fumes, ornaments,
+clocks, instruments, and the like should be removed. When all is
+ready the sulphur should be fired, the room tightly closed and left
+for twelve to twenty-four hours. Still more efficient in large houses,
+or where many hiding places favor the bugs, is fumigation with
+hydrocyanic acid gas. This is a deadly poison and must be used
+under rigid precautions. Through the courtesy of Professor Herrick,
+who has had much experience with this method, we give in the Appendix,
+the clear and detailed directions taken from his bulletin on
+"Household Insects."</p>
+
+<p>Fumigation with formaldehyde gas, either from the liquid or
+"solid" formalin, so efficient in the case of contagious diseases, is
+useless against bed-bugs and most other insects.</p>
+
+
+<p><a name="Other_Bed-bugs" id="Other_Bed-bugs"></a><b>Other Bed-bugs</b>&mdash;<i>Cimex hemipterus</i> (= <i>C. rotundatus</i>) is a tropical
+and subtropical species, occurring in both the old and new world.
+Patton and Cragg state that it is distributed throughout India,
+Burma, Assam, the Malay Peninsula, Aden, the Island of Mauritius,
+Reunion, St. Vincent and Porto Rico. "It is widely distributed
+in Africa, and is probably the common species associated there
+with man." Brumpt also records it for Cuba, the Antilles, Brazil,
+and Venezuela.</p>
+
+<p>This species, which is sometimes called the Indian bed-bug,
+differs from <i>C. lectularius</i> in being darker and in having a more
+elongate abdomen. The head also is shorter and narrower, and the
+prothorax has rounded borders.</p>
+
+<p>It has the same habits and practically the same life cycle as
+<i>Cimex lectularius</i>. Mackie, in India, has found that it is capable
+of transmitting the Asiatic type of recurrent fever. Roger suggested
+that it was also capable of transmitting Kala-azar and Patton has
+described in detail the developmental stages of <i>Leishmania</i>, the
+causative organism of Kala-azar, in the stomach of this bug, but
+Brumpt declares that the forms described are those of a common,
+non-pathogenic flagellate to be found in the bug, and have nothing<span class="pagenum"><a name="Page_92" id="Page_92">[Pg 92]</a></span>
+to do with the human disease. Brumpt has shown experimentally
+that <i>Cimex hemipterus</i> may transmit <i>Trypanosoma cruzi</i> in its excrement.</p>
+
+<p><i>Cimex boueti</i>, occurring in French Guinea, is another species
+attacking man. Its habits and general life history are the same as
+for the above species. It is 3 to 4.5 mm. in length,
+has vestigial elytra, and much elongated antennæ and
+legs. The extended hind legs are about as long as the
+body.</p>
+
+<p><i>Cimex columbarius</i>, a widely distributed species normally
+living in poultry houses and dove cotes, <i>C.&nbsp;inodorus</i>,
+infesting poultry in Mexico, <i>C.&nbsp;hirundinis</i>, occurring in
+the nests of swallows in Europe and <i>Oeciacus vicarius</i>
+(<a href="#Fig_19">fig.&nbsp;19i</a>) occurring in swallows' nests in this country,
+are species which occasionally infest houses and attack
+man.</p>
+
+<div class="figleft" style="width: 150px;"><a name="Fig_71" id="Fig_71"></a>
+<a href="images/f071-full.png"><img src="images/f071.png" width="150" height="271" alt="71. Conorhinus
+sanguisugus." title="71. Conorhinus
+sanguisugus." /></a>
+<span class="caption">71. Conorhinus
+sanguisugus.</span>
+</div>
+
+<p><i>Conorhinus sanguisugus</i>, the cone-nosed bed-bug. We have seen
+in our consideration of poisonous insects, that various species of
+Reduviid bugs readily attack man. Certain of these are nocturnal
+and are so commonly found in houses that they have gained the
+name, of "big bed-bugs." The most noted of these, in the United
+States, is <i>Conorhinus <span title="for sangiusugus read sanguisugus"><a name="AC_5a" id="AC_5a"></a>sangiusugus</span></i> (<a href="#Fig_71">fig.&nbsp;71</a>), which is widely distributed
+in our Southern States.</p>
+
+<p>Like its near relatives, <i>Conorhinus
+<span title="for sangiusugus read sanguisugus"><a name="AC_5b" id="AC_5b"></a>sangiusugus</span></i> is carnivorous in habit and
+feeds upon insects as well as upon
+mammalian and human blood. It is
+reported as often occurring in poultry
+houses and as attacking horses in
+barns. The life history has been
+worked out in considerable detail by
+Marlatt, (1902), from whose account we
+extract the following.</p>
+
+<div class="figright" style="width: 350px;"><a name="Fig_72" id="Fig_72"></a>
+<a href="images/f072-full.png"><img src="images/f072.png" width="350" height="419" alt="72. Beak of Conorhinus sanguisugus.
+After Marlatt." title="72. Beak of Conorhinus sanguisugus.
+After Marlatt." /></a>
+<span class="caption">72. Beak of Conorhinus sanguisugus.
+After Marlatt.</span>
+</div>
+
+<p>The eggs are white, changing to
+yellow and pink before hatching. The
+young hatch within twenty days
+and there are four nymphal stages.
+In all these stages the insect is active and predaceous, the mouth-parts
+(<a href="#Fig_72">fig.&nbsp;72</a>) being powerfully developed. The eggs are normally
+deposited, and the early stages are undoubtedly passed, out of doors,<span class="pagenum"><a name="Page_93" id="Page_93">[Pg 93]</a></span>
+the food of the immature forms being other insects. Immature
+specimens are rarely found indoors. It winters both in the partly
+grown and adult stage, often under the bark of trees or in any
+similar protection, and only in its nocturnal spring and early
+summer flights does it attack men. Marlatt states that this insect
+seems to be decidedly on the increase in the region which it particularly
+infests,&mdash;the plains region from Texas northward and westward.
+In California a closely related species of similar habits is
+known locally as the "monitor bug."</p>
+
+<p>The effect of the bite of the giant bed-bug on man is often very
+severe, a poisonous saliva apparently being injected into the wound.
+We have discussed this phase of the subject more fully under the
+head of poisonous insects.</p>
+
+<p><i>Conorhinus megistus</i> is a Brazilian species very commonly attacking
+man, and of special interest since Chagas has shown that it is
+the carrier of a trypanosomiasis of man. Its habits and life history
+have been studied in detail by Neiva, (1910).</p>
+
+<p>This species is now pre-eminently a household insect, depositing
+its eggs in cracks and crevices in houses, though this is a relatively
+recent adaptation. The nymphs emerge in from twenty to forty
+days, depending upon the temperature. There are five nymphal
+stages, and as in the case of true bed-bugs, the duration of these is
+very greatly influenced by the availability of food and by temperature.
+Neiva reckons the entire life cycle, from egg to egg, as requiring
+a minimum of three hundred and twenty-four days.</p>
+
+<p>The nymphs begin to suck blood in three to five days after hatching.
+They usually feed at night and in the dark, attacking especially
+the face of sleeping individuals. The bite occasions but little pain.
+The immature insects live in cracks and crevices in houses and
+invade the beds which are in contact with walls, but the adults are
+active flyers and attack people sleeping in hammocks. The males
+as well as the females are blood suckers.</p>
+
+<p>Like many blood-sucking forms, <i>Conorhinus megistus</i> can endure
+for long periods without food. Neiva received a female specimen
+which had been for fifty-seven days alive in a tightly closed box.
+They rarely feed on two consecutive days, even on small quantities
+of blood, and were never seen to feed on three consecutive days.</p>
+
+<p>Methods of control consist in screening against the adult bugs,
+and the elimination of crevices and such hiding places of the nymphs.
+Where the infestation is considerable, fumigation with sulphur is
+advisable.<span class="pagenum"><a name="Page_94" id="Page_94">[Pg 94]</a></span></p>
+
+
+<h3><a name="Parasitic_Diptera_or_Flies" id="Parasitic_Diptera_or_Flies"></a><span class="smcap">Parasitic Diptera or Flies</span></h3>
+
+<p>Of the <b>Diptera</b> or two-winged flies, many species occasionally
+attack man. Of these, a few are outstanding pests, many of them
+may also serve to disseminate disease, a phase of our subject which
+will be considered later. We shall now consider the most important
+of the group from the viewpoint of their direct attacks on man.</p>
+
+
+<h3><a name="Psychodidae_or_Moth-Flies" id="Psychodidae_or_Moth-Flies"></a>Psychodidæ or Moth-Flies</h3>
+
+<p>The <b>Psychodidæ</b> or Moth-flies, include a few species which attack
+man, and at least one species, <i>Phlebotomus papatasii</i>, is known
+to transmit the so-called "three-day fever" of man. Another species
+is supposed to be the vector of Peruvian verruga.</p>
+
+<p>The family is made up of small, sometimes very small, nematocerous
+Diptera, which are densely covered with hairs, giving them a
+moth-like appearance. The wings are relatively large, oval or
+lanceolate in shape, and when at rest are held in a sloping manner
+over the abdomen, or are held horizontally in such a way as to give
+the insect a triangular outline. Not only is the moth-like appearance
+characteristic, but the venation of the wings (<a href="#Fig_163">fig.&nbsp;163, d</a>) is very peculiar
+and, according to Comstock, presents an extremely generalized form.
+All of the longitudinal veins separate near the base of the wing
+except veins R<sub>2</sub> and R<sub>3</sub> and veins M<sub>1 </sub>and M<sub>2</sub>. Cross veins are
+wanting in most cases.</p>
+
+<p>Comparatively little is known regarding the life-history and
+habits of the Psychodidæ, but one genus, <i>Phlebotomus</i>, contains
+minute, blood-sucking species, commonly known as sand-flies. The
+family is divided into two subfamilies, the <b>Psychodinæ</b> and the
+<b>Phlebotominæ</b>. The second of these, the <b>Phlebotominæ</b>, is of
+interest to us.</p>
+
+
+<p><a name="The_Phlebotominae" id="The_Phlebotominae"></a><b>The Phlebotominæ</b>&mdash;The Phlebotominæ differ from the Psychodinæ
+in that the radical sector branches well out into the wing rather
+than at the base of the wing. They are usually less hairy than the
+Psychodinæ. The ovipositor is hidden and less strongly chitinized.
+The species attacking man belong to the genus <i>Phlebotomus</i>, small
+forms with relatively large, hairy wings which are held upright,
+and with elongate proboscis. The mandibles and maxillæ are serrated
+and fitted for biting.</p>
+
+<p>According to Miss Summers (1913) there are twenty-nine known
+species of the genus <i>Phlebotomus</i>, five European, eleven Asiatic,<span class="pagenum"><a name="Page_95" id="Page_95">[Pg 95]</a></span>
+seven African and six American. One species only, <i>Phlebotomus
+vexator</i>, has been reported for the United States. This was described
+by Coquillett, (1907), from species taken on Plummer's Island, Maryland.
+It measures only 1.5 mm. in length. As it is very probable
+that this species is much more widely distributed, and that other
+species of these minute flies will be found to occur in our fauna, we
+quote Coquillett's description.</p>
+
+<p><i>Phlebotomus vexator</i>, Coq.: Yellow, the mesonotum brown,
+hairs chiefly brown; legs in certain lights appear brown, but are
+covered with a white tomentum; wings hyaline, unmarked; the first
+vein (R<sub>1</sub>) terminates opposite one-fifth of the length of the first
+submarginal cell (cell R<sub>2</sub>); this cell is slightly over twice as long
+as its petiole; terminal, horny portion of male claspers slender,
+bearing many long hairs; the apex terminated by two curved spines
+which are more than one-half as long as the preceding part, and just
+in front of these are two similar spines, while near the middle of the
+length of this portion is a fifth spine similar to the others. Length
+1.5 mm.</p>
+
+<p>The life-history of the Phlebotomus flies has been best worked out
+for the European <i>Phlebotomus papatasii</i> and we shall briefly summarize
+the account of D&oelig;rr and Russ (1913) based primarily on work
+on this species. The European Phlebotomus flies appear at the
+beginning of the warm season, a few weeks after the cessation of the
+heavy rains and storms of springtime. They gradually become more
+abundant until they reach their first maximum, which in Italy is near
+the end of July (Grassi). They then become scarcer but reach a
+second maximum in September. At the beginning of winter they
+vanish completely, hibernating individuals not being found.</p>
+
+<p>After fertilization there is a period of eight to ten days before oviposition.
+The eggs are then deposited, the majority in a single mass
+covered by a slimy secretion from the sebaceous glands. The larvæ
+emerge in fourteen to twenty days. There is uncertainty as to the
+length of larval life, specimens kept in captivity remaining fifty or
+more days without transforming. Growth may be much more rapid
+in nature. The larvæ do not live in fluid media but in moist detritus
+in dark places. Marett believes that they live chiefly on the excrement
+of pill-bugs (Oniscidæ) and lizards. Pupation always occurs
+during the night. The remnants of the larval skin remain attached
+to the last two segments of the quiescent pupa and serve to attach
+it to the stone on which it lives. The pupal stage lasts eleven to
+sixteen days, the adult escaping at night.<span class="pagenum"><a name="Page_96" id="Page_96">[Pg 96]</a></span></p>
+
+<p>Only the females suck blood. They attack not only man but all
+warm-blooded animals and, according to recent workers, also cold-blooded
+forms, such as frogs, lizards, and larvæ. Indeed, Townsend
+(1914) believes that there is an intimate relation between <i>Phlebotomus</i>
+and lizards, or other reptiles the world over. The Phlebotomus
+passes the daylight hours within the darkened recesses of the loose
+stone walls and piles of rock in order to escape wind and strong light.
+Lizards inhabit the same places, and the flies, always ready to suck
+blood in the absence of light and wind, have been found more prone
+to suck reptilian than mammalian blood.</p>
+
+<p>On hot summer nights, when the wind is not stirring, the Phlebotomus
+flies, or sand-flies, as they are popularly called, invade houses and
+sleeping rooms in swarms and attack the inmates. As soon as light
+begins to break the flies either escape to the breeding places, or cool,
+dark places protected from the wind, or a part of them remain in the
+rooms, hiding behind pictures, under garments, and in similar places.
+Wherever the Phlebotomus flies occur they are an intolerable nuisance.
+On account of their small size they can easily pass through
+the meshes of ordinary screens and mosquito curtains. They attack
+silently and inflict a very painful, stinging bite, followed by itching.
+The ankles, dorsum of the feet, wrists, inner elbow, knee joint and
+similar places are favorite places of attack, possibly on account of
+their more delicate skin.</p>
+
+<p>Special interest has been attracted to these little pests in recent
+years, since it has been shown that they transmit the European
+"pappatici fever" or "three day fever." More recently yet, it
+appears that they are the carriers of the virus of the Peruvian "verruga."
+This phase of the subject will be discussed later.</p>
+
+<p>Control measures have not been worked out. As Newstead says,
+"In consideration of the facts which have so far been brought to light
+regarding the economy of Phlebotomus, it is clearly evident that the
+task of suppressing these insects is an almost insurmountable one.
+Had we to deal with insects as large and as accessible as mosquitoes,
+the adoption of prophylactic measures would be comparatively easy,
+but owing to the extremely minute size and almost flea-like habits of
+the adult insects, and the enormous area over which the breeding-places
+may occur, we are faced with a problem which is most difficult
+of solution." For these reasons, Newstead considers that the only
+really prophylactic measures which can at present be taken, are those
+which are considered as precautionary against the bites of the insects.<span class="pagenum"><a name="Page_97" id="Page_97">[Pg 97]</a></span></p>
+
+<p>Of repellents, he cites as one of the best a salve composed of the
+following:</p>
+
+<div class="center">
+<table border="0" cellpadding="4" cellspacing="0" summary="">
+<tr><td align="left">Ol. Anisi</td><td align="left">3 grs.</td></tr>
+<tr><td align="left">Ol. Eucalypti</td><td align="left">3 grs.</td></tr>
+<tr><td align="left">Ol. Terebenth</td><td align="left">3 grs.</td></tr>
+<tr><td align="left">Unq. Acid Borac.</td></tr>
+</table></div>
+
+<p>Of sprays he recommends as the least objectionable and at the
+same time one of the most effective, formalin. "The dark portions
+and angles of sleeping apartments should be sprayed with a one per
+cent. solution of this substance every day during the season in which
+the flies are prevalent. A fine spraying apparatus is necessary for
+its application and an excessive amount must not be applied. It is
+considered an excellent plan also to spray the mosquito curtains
+regularly every day towards sunset; nets thus treated are claimed to
+repel the attacks of these insects." This effectiveness of formalin is
+very surprising for, as we have seen, it is almost wholly ineffective
+against bed-bugs, mosquitoes, house flies and other insects, where it
+has been tried.</p>
+
+<p>A measure which promises to be very effective, where it can be
+adopted, is the use of electric fans so placed as to produce a current
+of air in the direction of the windows of sleeping apartments. On
+account of the inability of the Phlebotomus flies to withstand even
+slight breezes, it seems very probable that they would be unable to
+enter a room so protected.</p>
+
+
+<h3><a name="Culicidae_or_Mosquitoes" id="Culicidae_or_Mosquitoes"></a>Culicidæ or Mosquitoes</h3>
+
+<p>From the medical viewpoint, probably the most interesting and
+important of the blood-sucking insects are the mosquitoes. Certainly
+this is true of temperate zones, such as those of the United States.
+The result is that no other group of insects has aroused such widespread
+interest, or has been subjected to more detailed study than
+have the mosquitoes, since their rôle as carriers of disease was made
+known. There is an enormous literature dealing with the group, but
+fortunately for the general student, this has been well summarized
+by a number of workers. The most important and helpful of the
+general works are those of Howard (1901), Smith (1904), Blanchard
+(1905), Mitchell (1907), and especially of Howard, Dyar, and Knab,
+whose magnificent monograph is still in course of publication.<span class="pagenum"><a name="Page_98" id="Page_98">[Pg 98]</a></span></p>
+
+<p>Aside from their importance as carriers of disease, mosquitoes are
+notorious as pests of man, and the earlier literature on the group is
+largely devoted to references to their enormous numbers and their
+blood-thirstiness in certain regions. They are to be found in all
+parts of the world, from the equator to the Arctic and Antarctic
+regions. Linnæus, in the "Flora Lapponica," according to Howard,
+Dyar and Knab, "dwells at some length upon the great abundance of
+mosquitoes in Lapland and the torments they inflicted upon man and
+beast. He states that he believes that nowhere else on earth are they
+found in such abundance and he compares their numbers to the dust
+of the earth. Even in the open, you cannot draw your breath without
+having your mouth and nostrils filled with them; and ointments of
+tar and cream or of fish grease are scarcely sufficient to protect even
+the case-hardened cuticle of the Laplander from their bite. Even in
+their cabins, the natives cannot take a mouthful of food or lie down
+to sleep unless they are fumigated almost to suffocation." In some
+parts of the Northwestern and Southwestern United States it is
+necessary to protect horses working in the fields by the use of sheets or
+burlaps, against the ferocious attacks of these insects. It is a surprising
+fact that even in the dry deserts of the western United States
+they sometimes occur in enormous numbers.</p>
+
+<p>Until comparatively recent years, but few species of mosquitoes
+were known and most of the statements regarding their life-history
+were based upon the classic work of Reaumur (1738) on the biology
+of the rain barrel mosquito, <i>Culex pipiens</i>. In 1896, Dr. Howard
+refers to twenty-one species in the United States, now over fifty are
+known; Giles, in 1900, gives a total of two hundred and forty-two
+for the world fauna, now over seven hundred species are known.
+We have found eighteen species at Ithaca, N. Y.</p>
+
+<p>All of the known species of mosquitoes are aquatic in the larval
+stage, but in their life-histories and habits such great differences occur
+that we now know that it is not possible to select any one species as
+typical of the group. For our present purpose we shall first discuss
+the general characteristics and structure of mosquitoes, and shall
+then give the life-history of a common species, following this by a
+brief consideration of some of the more striking departures from what
+have been supposed to be the typical condition.</p>
+
+<p>The <b>Culicidæ</b> are slender, nematocerous Diptera with narrow wings,
+antennæ plumose in the males, and usually with the proboscis much
+longer than the head, slender, firm and adapted for piercing in the<span class="pagenum"><a name="Page_99" id="Page_99">[Pg 99]</a></span>
+female. The most characteristic feature is that the margins of the
+wings and, in most cases, the wing veins possess a fringe of scale-like
+hairs. These may also cover in part, or entirely, the head, thorax,
+abdomen and legs. The females, only, suck blood.</p>
+
+<p>On account of the importance of the group in this country and the
+desirability of the student being able to determine material in various
+stages, we show in the accompanying figures the characters most
+used in classification.</p>
+
+<p>The larvæ (<a href="#Fig_73">fig.&nbsp;73</a>) are elongate,
+with the head and thorax sharply
+distinct. The larval antennæ are
+prominent, consisting of a single
+cylindrical and sometimes curved
+segment. The outer third is often
+narrower and bears at its base a
+fan-shaped tuft of hairs, the arrangement
+and abundance of which
+is of systematic importance. About
+the mouth are the so-called rotary
+mouth brushes, dense masses of
+long hairs borne by the labrum
+and having the function of sweeping
+food into the mouth. The
+form and arrangement of thoracic,
+abdominal, and anal tufts of hair
+vary in different species and present
+characteristics of value. On either
+side of the eighth abdominal segment
+is a patch of scales varying
+greatly in arrangement and number and of much value in separating
+species. Respiration is by means of tracheæ which open at the apex
+of the so-called anal siphon, when it is present. In addition, there
+are also one or two pairs of tracheal gills which vary much in appearance
+in different species. On the ventral side of the anal siphon is a
+double row of flattened, toothed spines whose number and shape are
+likewise of some value in separating species. They constitute the
+comb or pecten.</p>
+
+<div class="figright" style="width: 300px;"><a name="Fig_73" id="Fig_73"></a>
+<a href="images/f073-full.png"><img src="images/f073.png" width="300" height="490" alt="73. Culex larva showing details of external
+structure." title="73. Culex larva showing details of external
+structure." /></a>
+<span class="caption">73. Culex larva showing details of external
+structure.</span>
+</div>
+
+<p>The pupa (<a href="#Fig_139">fig.&nbsp;139, b</a>) unlike that of most insects, is active, though it
+takes no food. The head and thorax are not distinctly separated, but
+the slender flexible abdomen in sharply marked off. The antennæ,<span class="pagenum"><a name="Page_100" id="Page_100">[Pg 100]</a></span>
+mouth-parts, legs, and wings of the future adult are now external, but
+enclosed in chitinous cases. On the upper surface, near the base of
+the wings are two trumpets, or breathing tubes, for the pupal spiracles
+are towards the anterior end instead of at the caudal end, as in the
+larva. At the tip of the abdomen is a pair of large chitinous swimming
+paddles.</p>
+
+<p>As illustrative of the life cycle of a mosquito we shall discuss the
+development of a common house mosquito, <i>Culex pipiens</i>, often
+referred to in the Northern United States as the rain barrel mosquito.
+Its life cycle is often given as typical for the entire group, but, as we
+have already emphasized, no one species can serve this purpose.</p>
+
+<p>The adults of <i>Culex pipiens</i> hibernate throughout the winter in
+cellars, buildings, hollow trees, or similar dark shelters. Early in
+the spring they emerge and deposit their eggs in a raft-like mass.
+The number of eggs in a single mass is in the neighborhood of two
+hundred, recorded counts varying considerably. A single female
+may deposit several masses during her life time. The duration of
+the egg stage is dependent upon temperature. In the warm summer
+time the larvæ may emerge within a day. The larvæ undergo four
+molts and under optimum conditions may transform into pupæ in
+about a week's time. Under the same favorable conditions, the pupal
+stage may be completed in a day's time. The total life cycle of <i>Culex
+pipiens</i>, under optimum conditions, may thus be completed in a week
+to ten days. This period may be considerably extended under less
+favorable conditions of temperature and food supply.</p>
+
+<p><i>Culex pipiens</i> breeds continuously throughout the summer,
+developing in rain barrels, horse troughs, tin cans, or indeed in any
+standing water about houses, which lasts for a week or more. The
+catch basins of sewers furnish an abundant supply of the pests under
+some conditions. Such places, the tin gutters on residences, and all
+possible breeding places must be considered in attempts to exterminate
+this species.</p>
+
+<p>Other species of mosquitoes may exhibit radical departures from
+<i>Culex pipiens</i> in life-history and habits. To control them it is essential
+that the biological details be thoroughly worked out for, as
+Howard, Dyar, and Knab have emphasized, "much useless labor and
+expense can be avoided by an accurate knowledge of the habits of the
+species." For a critical discussion of the known facts the reader is
+referred to their monograph. We shall confine ourselves to a few
+illustrations.<span class="pagenum"><a name="Page_101" id="Page_101">[Pg 101]</a></span></p>
+
+<p>The majority of mosquitoes in temperate climates hibernate in
+the egg stage, hatching in the spring or even mild winter days in water
+from melting snow. It is such single-brooded species which appear in
+astounding numbers in the far North. Similarly, in dry regions the
+eggs may stand thorough dessication, and yet hatch out with great
+promptness when submerged by the rains. "Another provision to
+insure the species against destruction in such a case, exists in the fact
+* * * that not all the eggs hatch, a part of them lying over until
+again submerged by subsequent rains." In temperate North
+America, a few species pass the winter in the larval state. An interesting
+illustration of this is afforded by <i>Wyeomia smithii</i>, whose
+larvæ live in pitcher plants and are to be found on the coldest winter
+days imbedded in the solid ice. Late in the spring, the adults emerge
+and produce several broods during the summer.</p>
+
+<p>In the United States, one of the most important facts which has
+been brought out by the intensive studies of recent years is that certain
+species are migratory and that they can travel long distances and
+become an intolerable pest many miles from their breeding places.
+This was forcibly emphasized in Dr. Smith's work in New Jersey,
+when he found that migratory mosquitoes, developing in the salt
+marshes along the coast, are the dominant species largely responsible
+for the fame of the New Jersey mosquito. The species concerned are
+<i>Aedes sollicitans</i>, <i>A. cantator</i> and <i>A. tæniorhynchus</i>. Dr. Smith
+decided that the first of these might migrate at least forty miles
+inland. It is obvious that where such species are the dominant pest,
+local control measures are a useless waste of time and money. Such
+migratory habits are rare, however, and it is probable that the
+majority of mosquitoes do not fly any great distance from their
+breeding places.</p>
+
+<p>While mosquitoes are thought of primarily as a pest of man, there
+are many species which have never been known to feed upon human
+or mammalian blood, no matter how favorable the opportunity.
+According to Howard, Dyar, and Knab, this is true of <i>Culex territans</i>,
+one of the common mosquitoes in the summer months in the Northern
+United States. There are some species, probably many, in which
+the females, like the males, are plant feeders. In experimental work,
+both sexes are often kept alive for long periods by feeding them upon
+ripe banana, dried fig, raisins, and the like, and in spite of sweeping
+assertions that mosquitoes must have a meal of blood in order to
+stimulate the ovaries to development, some of the common blood-sucking<span class="pagenum"><a name="Page_102" id="Page_102">[Pg 102]</a></span>
+species, notably <i>Culex pipiens</i>, have been bred repeatedly
+without opportunity to feed upon blood.</p>
+
+<p>The effect of the bite varies greatly with different species and
+depends upon the susceptibility of the individual bitten. Some
+persons are driven almost frantic by the attacks of the pests when
+their companions seem almost unconscious of any inconvenience.
+Usually, irritation and some degree of inflammation appear shortly
+following the bite. Not infrequently a hardened wheal or even a
+nodule forms, and sometimes scratching leads to secondary infection
+and serious results.</p>
+
+<p>The source of the poison is usually supposed to be the salivary
+glands of the insect. As we have already pointed out, (<a href="#Page_34">p. 34</a>),
+Macloskie believed that one lobe of the gland, on each side, was
+specialized for forming the poison, while a radically different view is
+that of Schaudinn, who believed that the irritation is due to the
+expelled contents of the &oelig;sophageal diverticula, which contain a
+gas and a peculiar type of fungi or bacteria. In numerous attempts,
+Schaudinn was unable to produce any irritation by applying the
+triturated salivary glands to a wound, but obtained the typical result
+when he used the isolated diverticula.</p>
+
+<p>The irritation of the bite may be relieved to some extent by using
+ammonia water, a one per cent. alcoholic solution of menthol, or
+preparations of cresol, or carbolic acid. Dr. Howard recommends
+rubbing the bite gently with a piece of moist toilet soap. Castellani
+and Chalmers recommend cleansing inflamed bites with one in forty
+carbolic lotion, followed by dressing with boracic ointment. Of
+course, scratching should be avoided as much as possible.</p>
+
+<p>Repellents of various kinds are used, for warding off the attacks
+of the insects. We have often used a mixture of equal parts of oil
+of pennyroyal and kerosene, applied to the hands and face. Oil of
+citronella is much used and is less objectionable to some persons. A
+recommended formula is, oil of citronella one ounce, spirits of camphor
+one ounce, oil of cedar one-half ounce. A last resort would seem to
+be the following mixture recommended by Howard, Dyar, and Knab
+for use by hunters and fishermen in badly infested regions, against
+mosquitoes and blackflies.</p>
+
+<p>Take 2&frac14; lbs. of mutton tallow and strain it. While still hot add
+&frac12; lb. black tar (Canadian tar). Stir thoroughly and pour into the
+receptacle in which it is to be contained. When nearly cool stir in
+three ounces of oil of citronella and 1&frac14; oz. of pennyroyal.<span class="pagenum"><a name="Page_103" id="Page_103">[Pg 103]</a></span></p>
+
+<p>At night the surest protection is a good bed net. There are many
+types of these in use, but in order to be serviceable and at the same
+time comfortable it should be roomy and hung in such a way as to
+be stretched tightly in every direction. We prefer one suspended
+from a broad, square frame, supported by a right-angled standard
+which is fastened to the head of the bed. It must be absolutely free
+from rents or holes and tucked in securely under the mattress or it
+will serve merely as a convenient cage to retain mosquitoes which gain
+an entrance. While such nets are a convenience in any mosquito
+ridden community, they are essential in regions where disease-carrying
+species abound. Screening of doors, windows and porches, against
+the pests is so commonly practiced in this country that its importance
+and convenience need hardly be urged.</p>
+
+<p>Destruction of mosquitoes and prevention of breeding are of
+fundamental importance. Such measures demand first, as we have
+seen, the correct determination of the species which is to be dealt
+with, and a knowledge of its life-history and habits. If it prove to be
+one of the migratory forms, it is beyond mere local effort and becomes
+a problem demanding careful organization and state control. An
+excellent illustration of the importance and effectiveness of work
+along these lines is afforded by that in New Jersey, begun by the late
+Dr. John B. Smith and being pushed with vigor by his successor,
+Dr. Headlee.</p>
+
+<p>In any case, there is necessity for community action. Even near
+the coast, where the migratory species are dominant, there are the
+local species which demand attention and which cannot be reached
+by any measures directed against the species of the salt marshes. The
+most important of local measures consist in the destruction of breeding
+places by filling or draining ponds and pools, clearing up of more
+temporary breeding places, such as cans, pails, water barrels and the
+like. Under conditions where complete drainage of swamps is impracticable
+or undesirable, judicious dredging may result in a pool or
+series of steep-sided pools deep enough to maintain a supply of fish,
+which will keep down the mosquito larvæ. Where water receptacles
+are needed for storage of rain water, they should be protected by
+careful screening or a film of kerosene over the top of the water,
+renewed every two weeks or so, so as to prevent mosquitoes from
+depositing their eggs. When kerosene is used, Water drawn from the
+bottom of the receptacle will not be contaminated by it to any injurious
+extent. Where ponds cannot be drained much good will be<span class="pagenum"><a name="Page_104" id="Page_104">[Pg 104]</a></span>
+accomplished by spraying kerosene oil on the surface of the water, or
+by the introduction of fish which will feed on the larvæ.</p>
+
+<div class="figleft" style="width: 350px;"><a name="Fig_74" id="Fig_74"></a>
+<a href="images/f074-full.jpg"><img src="images/f074.jpg" width="350" height="244" alt="74. Mouth parts of Simulium. After
+Grünberg." title="74. Mouth parts of Simulium. After
+Grünberg." /></a>
+<span class="caption">74. Mouth parts of Simulium. After
+Grünberg.</span>
+</div>
+
+<p>Detailed consideration of the
+most efficient measures for controlling
+mosquitoes is to be found
+in Dr. Howard's Bulletin No. 88
+of the Bureau of Entomology,
+"Preventive and remedial work
+against mosquitoes" or, in more
+summarized form, in Farmers'
+Bulletin No. 444. One of these
+should be obtained by any person
+interested in the problems of mosquito
+control and public health.</p>
+
+
+<h3><a name="The_Simuliidae_or_Black_Flies" id="The_Simuliidae_or_Black_Flies"></a>The Simuliidæ, or Black Flies</h3>
+
+<div class="figright" style="width: 150px;"><a name="Fig_75" id="Fig_75"></a>
+<a href="images/f075-full.png"><img src="images/f075.png" width="150" height="502" alt="75. Larva of Simulium,
+(×8).
+After Garman." title="75. Larva of Simulium,
+(×8).
+After Garman." /></a>
+<span class="caption">75. Larva of Simulium,
+(×8).
+After Garman.</span>
+</div>
+
+<p>The <b>Simuliidæ</b>, or black flies, are small, dark, or black flies, with
+a stout body and a hump-back appearance. The
+antennæ are short but eleven-segmented, the wings
+broad, without scales or hairs, and with the anterior
+veins stout but the others very weak. The mouth-parts
+(<a href="#Fig_74">fig.&nbsp;74</a>) are fitted for biting.</p>
+
+<p>The larvæ of the Simuliidæ (<a href="#Fig_75">fig.&nbsp;75</a>) are aquatic
+and, unlike those of mosquitoes, require a well ærated,
+or swiftly running water. Here they attach to stones,
+logs, or vegetation and feed upon various micro-organisms.
+They pupate in silken cocoons open at
+the top. Detailed life-histories have not been worked
+out for most of the species. We shall consider as
+typical that of <i>Simulium pictipes</i>, an inoffensive
+species widely distributed in the Eastern United
+States, which has been studied especially at Ithaca,
+N.Y. (Johannsen, 1903).</p>
+
+<p>The eggs are deposited in a compact yellowish layer
+on the surface of rock, on the brinks of falls and
+rapids where the water is flowing swiftly. They are
+elongate ellipsoidal in shape, about .4 by .18 mm.
+As myriads of females deposit in the same place the
+egg patches may be conspicuous coatings of a foot or much more
+in diameter. When first laid they are enveloped in a yellowish<span class="pagenum"><a name="Page_105" id="Page_105">[Pg 105]</a></span>
+white slime, which becomes darker, until finally it becomes black just
+before the emerging of the larvæ. The egg stage lasts a week.</p>
+
+<p>The larvæ (<a href="#Fig_75">fig.&nbsp;75</a>) are black, soft skinned, somewhat cylindrical
+in shape, enlarged at both ends and attenuated in the middle. The
+posterior half is much stouter than the anterior part and almost club-shaped.
+The head bears two large fan-shaped organs which aid in
+procuring food. Respiration is accomplished by means of three so-called
+blood gills which are pushed out from the dorsal part of the
+rectum. The larvæ occur in enormous numbers, in moss-like patches.
+If removed from their natural habitat and placed in quiet water they
+die within three or four hours. Fastened to the rock by means of a
+disk-like sucker at the caudal end of
+the body, they ordinarily assume an
+erect position. They move about on
+the surface of the rocks, to a limited
+extent, with a looping gait similar to
+that of a measuring worm, and a web
+is secreted which prevents their being
+washed away by the swiftly flowing
+water. They feed chiefly upon algæ
+and diatoms.</p>
+
+<p>The complete larval stage during
+the summer months occupies about
+four weeks, varying somewhat with the
+temperature and velocity of the water.
+At the end of this period they spin
+from cephalic glands, boot-shaped
+silken cocoons within which they pupate. The cocoon when spun
+is firmly attached to the rock and also to adjacent cocoons.
+Clustered continuously over a large area and sometimes one above
+another, they form a compact, carpet-like covering on the rocks,
+the reddish-brown color of which is easily distinguishable from the
+jet-black appearance of the larvæ. The pupal stage lasts about
+three weeks. The adult fly, surrounded by a bubble of air, quickly
+rises to the surface of the water and escapes. The adults (<a href="#Fig_76">fig.&nbsp;76</a>)
+are apparently short lived and thus the entire life cycle, from egg
+to egg is completed in approximately eight weeks.</p>
+
+<div class="figright" style="width: 350px;"><a name="Fig_76" id="Fig_76"></a>
+<a href="images/f076-full.png"><img src="images/f076.png" width="350" height="450" alt="76. Simulium venustum, (×8).
+After Garman." title="76. Simulium venustum, (×8).
+After Garman." /></a>
+<span class="caption">76. Simulium venustum, (×8).
+After Garman.</span>
+</div>
+
+<p>In the case of <i>Simulium pictipes</i> at Ithaca, N.&nbsp;Y., the first brood
+of adults emerges early in May and successive generations are produced
+throughout the summer and early autumn. This species winters in<span class="pagenum"><a name="Page_106" id="Page_106">[Pg 106]</a></span>
+the larval condition. Most of the other species of <i>Simulium</i> which
+have been studied seem to be single brooded.</p>
+
+<p>While <i>Simulium pictipes</i> does not attack man, there are a number
+of the species which are blood-sucking and in some regions they are a
+veritable scourge. In recent years the greatest interest in the group
+has been aroused by Sambon's hypothesis that they transmit pellagra
+from man to man. This has not been established, and, indeed, seems
+very doubtful, but the importance of these insects as pests and the
+possibility that they may carry disease make it urgent that detailed
+life-histories of the hominoxious species be worked out.</p>
+
+<p>As pests a vivid account of their attacks is in Agassiz's "Lake
+Superior" (p.&nbsp;61), quoted by Forbes (1912).</p>
+
+<p>"Neither the love of the picturesque, however, nor the interests of
+science, could tempt us into the woods, so terrible were the black flies.
+This pest of flies which all the way hither had confined our ramblings
+on shore pretty closely to the rocks and the beach, and had been
+growing constantly worse, here reached its climax. Although detained
+nearly two days, *&nbsp;*&nbsp;* we could only sit with folded
+hands, or employ ourselves in arranging specimens, and such other
+operations as could be pursued in camp, and under the protection of
+a 'smudge.' One, whom scientific ardor tempted a little way up the
+river in a canoe, after water plants, came back a frightful spectacle,
+with blood-red rings round his eyes, his face bloody, and covered with
+punctures. The next morning his head and neck were swollen as if
+from an attack of erysipelas."</p>
+
+<p>There are even well authenticated accounts on record of death of
+humans from the attacks of large swarms of these gnats. In some
+regions, and especially in the Mississippi Valley in this country, certain
+species of black flies have been the cause of enormous losses to
+farmers and stockmen, through their attacks on poultry and domestic
+animals. C.&nbsp;V. Riley states that in 1874 the loss occasioned in one
+county in Tennessee was estimated at $500,000.</p>
+
+<p>The measures of prevention and protection against these insects
+have been well summarized by Forbes (1912). They are of two kinds:
+"the use of repellents intended to drive away the winged flies, and
+measures for the local destruction of the aquatic larvæ. The repellents
+used are either smudges, or surface applications made to keep
+the flies from biting. The black-fly will not endure a dense smoke,
+and the well-known mosquito smudge seems to be ordinarily sufficient
+for the protection of man. In the South, leather, cloth, and other<span class="pagenum"><a name="Page_107" id="Page_107">[Pg 107]</a></span>
+materials which will make the densest and most stifling smoke, are
+often preserved for this use in the spring. Smudges are built in
+pastures for the protection of stock, and are kept burning before the
+doors of barns and stables. As the black-flies do not readily enter a
+dark room, light is excluded from stables as much as possible during
+the gnat season. If teams must be used in the open field while gnats
+are abroad, they may be protected against the attacks of the gnats by
+applying cotton-seed oil or axle grease to the surface, especially to the
+less hairy parts of the animals, at least twice a day. A mixture of oil
+and tar and, indeed, several other preventives, are of practical use in
+badly infested regions; but no definite test or exact comparison has
+been made with any them in a way to give a record of the precise
+results."</p>
+
+<p>"It is easy to drive the flies from houses or tents by burning
+pyrethrum powder inside; this either kills the flies or stupifies them
+so that they do not bite for some time thereafter." *&nbsp;*&nbsp;* "Oil of
+tar is commonly applied to the exposed parts of the body for the purpose
+of repelling the insects, and this preparation is supplied by the
+Hudson Bay Company to its employees. Minnesota fishermen
+frequently grease their faces and hands with a mixture of kerosene
+and mutton tallow for the same purpose." We have found a mixture
+of equal parts of kerosene and oil of pennyroyal efficient.</p>
+
+<p>Under most circumstances very little can be done to destroy this
+insect in its early stage, but occasionally conditions are such that a
+larvicide can be used effectively. Weed (1904), and Sanderson (1910)
+both report excellent results from the use of phinotas oil, a proprietary
+compound. The first-mentioned also found that in some places the
+larvæ could be removed by sweeping them loose in masses with stiff
+stable brooms and then catching them downstream on wire netting
+stretched in the water.</p>
+
+
+<h3><a name="Chironomidae_or_Midges" id="Chironomidae_or_Midges"></a>Chironomidæ or Midges</h3>
+
+<p>The flies of this family, commonly known as midges, resemble
+mosquitoes in form and size but are usually more delicate, and the
+wing-veins, though sometimes hairy, are not fringed with scales.
+The venation is simpler than in the mosquitoes and the veins are
+usually less distinct.</p>
+
+<p>These midges, especially in spring or autumn, are often seen in
+immense swarms arising like smoke over swamps and producing a
+humming noise which can be heard for a considerable distance. At<span class="pagenum"><a name="Page_108" id="Page_108">[Pg 108]</a></span>
+these seasons they are frequently to be found upon the windows of
+dwellings, where they are often mistaken for mosquitoes.</p>
+
+<p>The larvæ are worm-like, but vary somewhat in form in the different
+genera. Most of them are aquatic, but a few live in the earth, in
+manure, decaying wood, under bark, or in the sap of trees, especially
+in the sap which collects in wounds.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_77" id="Fig_77"></a>
+<a href="images/f077-full.png"><img src="images/f077.png" width="500" height="348" alt="77. Culicoides guttipennis; (a) adult, (×15); (b) head of same; (c) larva;
+(d) head; (e) pupa. After Pratt." title="77. Culicoides guttipennis; (a) adult, (×15); (b) head of same; (c) larva;
+(d) head; (e) pupa. After Pratt." /></a>
+<span class="caption">77. Culicoides guttipennis; (<i>a</i>)&nbsp;adult, (×15); (<i>b</i>)&nbsp;head of same; (<i>c</i>)&nbsp;larva;
+(<i>d</i>)&nbsp;head; (<i>e</i>)&nbsp;pupa. After Pratt.</span>
+</div>
+
+<p>Of the many species of <b>Chironomidæ</b>, (over eight hundred known),
+the vast majority are inoffensive. The sub-family Ceratopogoninæ,
+however, forms an exception, for some of the members of this group,
+known as sandflies, or punkies, suck blood and are particularly troublesome
+in the mountains, along streams, and at the seashore. Most of
+these have been classed under the genus <i>Ceratopogon</i>, but the group
+has been broken up into a number of genera and <i>Ceratopogon</i>, in the
+strict sense, is not known to contain any species which sucks the blood
+of vertebrates.</p>
+
+<p><b>The Ceratopogoninæ</b>&mdash;The Ceratopogoninæ are among the smallest
+of the Diptera, many of them being hardly a millimeter long and some
+not even so large. They are Chironomidæ in which the thorax is not
+prolonged over the head. The antennæ are filiform with fourteen
+(rarely thirteen) segments in both sexes, those of the male being brush-like.
+The basal segment is enlarged, the last segment never longer<span class="pagenum"><a name="Page_109" id="Page_109">[Pg 109]</a></span>
+than the two preceding combined, while the last five are sub-equal to,
+or longer than the preceding segment. The legs are relatively stouter
+than in the other Chironomidæ. The following three genera of this
+subfamily are best known as blood suckers in this country.</p>
+
+<div class="figright" style="width: 300px;"><a name="Fig_78" id="Fig_78"></a>
+<a href="images/f078-full.png"><img src="images/f078.png" width="300" height="352" alt="78. Culicoides guttipennis; mouth
+parts of adult. After Pratt." title="78. Culicoides guttipennis; mouth
+parts of adult. After Pratt." /></a>
+<span class="caption">78. Culicoides guttipennis; mouth
+parts of adult. After Pratt.</span>
+</div>
+
+<p>Of the genus <i>Culicoides</i> there are many species occurring in various
+parts of the world. A number are known to bite man and animals and
+it is probable that all are capable of inflicting injury. In some
+localities they are called punkies, in others, sand-flies, a name sometimes
+also applied to the species of <i>Simulium</i> and <i>Phlebotomus</i>.
+Owing to their very small size they are known by some tribes of
+Indians as No-see-ums. The larvæ are found in ponds, pools, water
+standing in hollow tree stumps, and the like. Though probably living
+chiefly in fresh water, we have found a species occurring in salt water.
+The larvæ are small, slender, legless,
+worm-like creatures (<a href="#Fig_77">fig.&nbsp;77<i>c</i></a>) with
+small brown head and twelve body
+segments. The pupæ (<a href="#Fig_77">fig.&nbsp;77<i>e</i></a>) are
+slender, more swollen at the anterior
+end and terminating in a forked process.
+They float nearly motionless in
+a vertical position, the respiratory
+tubes in contact with the surface film.
+The adults are all small, rarely exceeding
+2&frac14; mm. in length. The wings
+are more or less covered with erect
+setulæ or hairs and in many species
+variously spotted and marked with
+iridescent blotches. The antennæ have fourteen segments, the palpi
+usually five. The wing venation and mouth-parts are shown in
+figures&nbsp;<a href="#Fig_77">77</a> and&nbsp;<a href="#Fig_78">78</a>. Of the twenty or more species of this genus
+occurring in the United States the following are known to bite: <i>C.&nbsp;cinctus</i>,
+<i>C.&nbsp;guttipennis</i>, <i>C.&nbsp;sanguisuga</i>, <i>C.&nbsp;stellifer</i>, <i>C.&nbsp;variipennis</i>,
+<i>C.&nbsp;unicolor</i>.</p>
+
+<p>One of the most widely distributed and commonest species in the
+Eastern States is <i>C.&nbsp;guttipennis</i> (<a href="#Fig_77">fig.&nbsp;77a</a>). It is black with brown
+legs, a whitish ring before the apex of each femur and both ends of
+each tibia; tarsi yellow, knobs of halteres yellow. Mesonotum
+opaque, brown, two vittæ in the middle, enlarging into a large spot
+on the posterior half, also a curved row of three spots in front of each
+wing, and the narrow lateral margins, light gray pruinose. Wings<span class="pagenum"><a name="Page_110" id="Page_110">[Pg 110]</a></span>
+nearly wholly covered with brown hairs, gray, with markings as
+shown in the figure. Length one mm.</p>
+
+<p><i>Johannseniella</i> Will. is a
+wide-spread genus related
+to the foregoing. Its
+mouth-parts are well
+adapted for piercing and
+it is said to be a persistent
+blood sucker, particularly
+in Greenland. This genus
+is distinguished from <i>Culicoides</i>
+by its bare wings,
+the venation (<a href="#Fig_163">fig.&nbsp;163</a>,&nbsp;c),
+and the longer tarsal claws.
+There are over twenty
+North American species.</p>
+
+<div class="figcenter" style="width: 320px;">
+<a href="images/f079-full.png"><img src="images/f079.png" width="320" height="254" alt="79. Chrysops univittatus, (×4). After Osborn." title="79. Chrysops univittatus, (×4). After Osborn." /></a>
+<span class="caption">79. Chrysops univittatus, (×4). After Osborn.</span>
+</div>
+
+<p>In the Southwestern United States, <i>Tersesthes torrens</i> Towns.
+occurs, a little gnat which annoys horses, and perhaps man also, by
+its bite. It is related to <i>Culicoides</i> but differs in the number of
+antennal segments and in its wing venation (<a href="#Fig_163">fig.&nbsp;163</a>, e). The fly
+measures but two mm. in length and is blackish in color. The
+antennæ of the female have thirteen segments, the palpi but three, of
+which the second is enlarged and swollen.</p>
+
+
+<h3><a name="Tabanidae_or_Horse-Flies" id="Tabanidae_or_Horse-Flies"></a>Tabanidæ or Horse-Flies</h3>
+
+<div class="figleft" style="width: 250px;"><a name="Fig_80a" id="Fig_80a"></a>
+<a href="images/f080a-full.jpg"><img src="images/f080a.png" width="250" height="806" alt="80. (a) Eggs of Tabanus. Photograph
+by J. T. Lloyd." title="80. (a) Eggs of Tabanus. Photograph
+by J. T. Lloyd." /></a>
+<span class="caption">80. (<i>a</i>)&nbsp;Eggs of Tabanus. Photograph
+by J.&nbsp;T. Lloyd.</span>
+</div>
+
+<div class="figright" style="width: 250px;"><a name="Fig_80b" id="Fig_80b"></a>
+<a href="images/f080b-full.jpg"><img src="images/f080b.png" width="250" height="601" alt="80. (b) Larva of Tabanus.
+Photograph by M. V. S." title="80. (b) Larva of Tabanus.
+Photograph by M. V. S." /></a>
+<span class="caption">80. (<i>b</i>)&nbsp;Larva of Tabanus.
+Photograph by M.&nbsp;V.&nbsp;S.</span>
+</div>
+
+<p>The <b>Tabanidæ</b>,&mdash;horse-flies, ear-flies, and deer-flies,&mdash;are well-known
+pests of cattle and horses and are often extremely annoying
+to man. The characteristics of the family and of the principal North
+American genera are given in the keys of Chapter XII. There are
+over 2500 recorded species. As in the mosquitoes, the females
+alone are blood suckers. The males are flower feeders or live on
+plant juices. This is apparently true also of the females of some of
+the genera.</p>
+
+<p>The eggs are deposited in masses on water plants or grasses and
+sedges growing in marshy or wet ground. Those of a common
+species of <i>Tabanus</i> are illustrated in <a href="#Fig_80a">figure&nbsp;80, <i>a</i></a>. They are placed
+in masses of several hundred, light colored when first deposited but
+turning black. In a week or so the cylindrical larvæ, tapering at
+both ends (<a href="#Fig_80b">fig.&nbsp;80, <i>b</i></a>), escape to the water, or damp earth, and lead<span class="pagenum"><a name="Page_111" id="Page_111">[Pg 111]</a></span>
+an active, carnivorous life, feeding mainly on insect larvæ, and worms.
+In the forms which have been best studied the larval life is a long
+one, lasting for months or even for more
+than a year. Until recently, little was
+known concerning the life-histories of this
+group, but the studies of Hart (1895),
+and Hine (1903&nbsp;+)
+have added
+greatly to the
+knowledge concerning
+North
+American
+forms.</p>
+
+<p>Many of the
+species attack
+man with avidity
+and are able
+to inflict painful
+bites, which
+may smart for
+hours. In some
+instances the
+wound is so
+considerable
+that blood will
+continue to flow
+after the fly has
+left. We have
+seen several
+cases of secondary infection following
+such bites.</p>
+
+<p>The horse-flies have been definitely
+convicted of transferring the trypanosome
+of surra from diseased to healthy animals
+and there is good evidence that they transfer anthrax. The possibility
+of their being important agents in the conveyal of human
+diseases should not be overlooked. Indeed, Leiper has recently
+determined that a species of <i>Chrysops</i> transfers the blood parasite
+<i>Filaria diurna</i>.<span class="pagenum"><a name="Page_112" id="Page_112">[Pg 112]</a></span></p>
+
+
+<h3><a name="Leptidae_or_Snipe-Flies" id="Leptidae_or_Snipe-Flies"></a>Leptidæ or Snipe-Flies</h3>
+
+<p>The family <b>Leptidæ</b> is made up of moderate or large sized flies,
+predaceous in habit. They are sufficiently characterized in the keys
+of Chapter XII. Four blood-sucking
+species belonging to three
+genera have been reported. Of
+these <i>Symphoromyia pachyceras</i> is
+a western species. Dr. J. C.
+Bradley, from personal experience,
+reports it as a vicious biter.</p>
+
+<div class="figcenter" style="width: 400px;">
+<a href="images/f080c-full.png"><img src="images/f080c.png" width="400" height="346" alt="80. (c) Mouth parts of Tabanus. After Grünberg." title="80. (c) Mouth parts of Tabanus. After Grünberg." /></a>
+<span class="caption">80. (<i>c</i>)&nbsp;Mouth parts of Tabanus. After Grünberg.</span>
+</div>
+
+
+<h3><a name="Oestridae_or_Bot-flies" id="Oestridae_or_Bot-flies"></a>Oestridæ or Bot-flies</h3>
+
+<p>To the family <b>Oestridæ</b> belong
+the bot and warble-flies so frequently
+injurious to animals.
+The adults are large, or of
+medium size, heavy bodied, rather
+hairy, and usually resemble bees in appearance.</p>
+
+<p>The larvæ live parasitically in various parts of the body of mammals,
+such as the stomach (horse bot-fly), the subcutaneous connective
+tissue (warble-fly of cattle), or the nasal passage (sheep bot-fly
+or head maggot).</p>
+
+<p>There are on record many cases of the occurrence of the larvæ
+of Oestridæ as occasional parasites of man. A number of these have
+been collected and reviewed in a thesis by Mme. Pètrovskaia (1910).
+The majority of them relate to the following species.</p>
+
+<p><i>Gastrophilus hæmorrhoidalis</i>, the red tailed bot-fly, is one of the
+species whose larvæ are most commonly found in the stomach of the
+horse. Schoch (1877) cites the case of a woman who suffered from
+a severe case of chronic catarrh of the stomach, and who vomited,
+and also passed from the anus, larvæ which apparently belonged
+to this species. Such cases are exceedingly rare but instances of
+subcutaneous infestation are fairly numerous. In the latter type
+these larvæ are sometimes the cause of the peculiar "creeping myasis."
+This is characterized at its beginning by a very painful swelling
+which gradually migrates, producing a narrow raised line four to
+twenty-five millimeters broad. When the larva is mature, sometimes
+after several months, it becomes stationary and a tumor is formed
+which opens and discharges the larva along with pus and serum.<span class="pagenum"><a name="Page_113" id="Page_113">[Pg 113]</a></span></p>
+
+<p><i>Gastrophilus equi</i> is the most widespread and common of the horse
+bot-flies. Portschinsky reports it as commonly causing subcutaneous
+myasis of man in Russia.</p>
+
+<p><i>Hypoderma bovis</i> (= <i>Oestrus bovis</i>), and <i>Hypoderma lineata</i> are
+the so-called warble-flies of cattle. The latter species is the more
+common in North America but Dr. C. G. Hewitt has recently shown
+that <i>H. bovis</i> also occurs. Though warbles are very common in
+cattle in this country, the adult flies are very rarely seen. They
+are about half an inch in length, very hairy, dark, and closely resemble
+common honey-bees.</p>
+
+<p>They deposit their eggs on the hairs of cattle and the animals in
+licking themselves take in the young larvæ. These pass out through
+the walls of the &oelig;sophagus and migrate through the tissues of the
+animal, to finally settle down in the subcutaneous tissue of the back.
+The possibility of their entering directly through the skin, especially
+in case of infestation of man, is not absolutely precluded, although
+it is doubtful.</p>
+
+<p>For both species of <i>Hypoderma</i> there are numerous cases on
+record of their occurrence in man. Hamilton (1893) saw a boy,
+six years of age, who had been suffering for some months from the
+glands on one side of his neck being swollen and from a fetid ulceration
+around the back teeth of the lower jaw of the same side. Three
+months' treatment was of no avail and the end seemed near; one day
+a white object, which was seen to move, was observed in the ulcer
+at the root of the tongue, and on being extracted was recognized as a
+full grown larva of <i>Hypoderma</i>. It was of usual tawny color, about
+half an inch long when contracted, about one third that thickness,
+and quite lively. The case resulted fatally. The boy had been on a
+dairy farm the previous fall, where probably the egg (or larva) was
+in some way taken into his mouth, and the larva found between the
+base of the tongue and the jaw suitable tissue in which to develop.</p>
+
+<p>Topsent (1901) reports a case of "creeping myasis" caused by
+<i>H. lineata</i> in the skin of the neck and shoulders of a girl eight years
+of age. The larva travelled a distance of nearly six and a half inches.
+The little patient suffered excruciating pain in the place occupied by
+the larva.</p>
+
+<p><i>Hypoderma diana</i> infests deer, and has been known to occur in
+man.</p>
+
+<p><i>Oestris ovis</i>, the sheep bot-fly, or head maggot, is widely distributed
+in all parts of the world. In mid-summer the flies deposit<span class="pagenum"><a name="Page_114" id="Page_114">[Pg 114]</a></span>
+living maggots in the nostrils of sheep. These larvæ promptly pass
+up the nasal passages into the frontal and maxillary sinuses, where
+they feed on the mucous to be found there. In their migrations
+they cause great irritation to their host, and when present in numbers
+may cause vertigo, paroxysms, and even death. Portschinsky in an
+important monograph on this species, has discussed in detail its
+relation to man. He shows that it is not uncommon for the fly to
+attack man and that the minute living larvæ are deposited in the
+eyes, nostrils, lips, or mouth. A typical case in which the larvæ
+were deposited in the eye was described by a German oculist Kayser,
+in 1905. A woman brought her six year old daughter to him and
+said that the day before, about noontime, a flying insect struck the
+eye of the child and that since then she had felt a pain which increased
+towards evening. In the morning the pain ceased but the
+eye was very red. She was examined at about noon, at which time
+she was quiet and felt no pain. She was not sensitive to light, and
+the only thing noticed was a slight congestion and accumulation of
+secretion in the corner of the right eye. A careful examination of
+the eye disclosed small, active, white larvæ that crawled out from
+the folds of the conjunctiva and then back and disappeared. Five
+of these larvæ were removed and although an uncomfortable feeling
+persisted for a while, the eye became normal in about three weeks.</p>
+
+<p>Some of the other recorded cases have not resulted so favorably,
+for the eyesight has been seriously affected or even lost.</p>
+
+<p>According to Edmund and Etienne Sergent (1907), myasis caused
+by the larvæ of <i>Oestris ovis</i> is very common among the shepherds in
+Algeria. The natives say that the fly deposits its larvæ quickly,
+while on the wing, without pause. The greatest pain is caused when
+these larvæ establish themselves in the nasal cavities. They then
+produce severe frontal headaches, making sleep impossible. This
+is accompanied by continuous secretion from the nasal cavities
+and itching pains in the sinuses. If the larvæ happen to get into
+the mouth, the throat becomes inflamed, swallowing is painful,
+and sometimes vomiting results. The diseased condition may last
+for from three to ten days or in the case of nasal infection, longer,
+but recovery always follows. The natives remove the larvæ from
+the eye mechanically by means of a small rag. When the nose is
+infested, tobacco fumigations are applied, and in case of throat
+infestation gargles of pepper, onion, or garlic extracts are used.<span class="pagenum"><a name="Page_115" id="Page_115">[Pg 115]</a></span></p>
+
+<p><i>Rhin&oelig;strus nasalis</i>, the Russian gad-fly, parasitizes the nasopharyngeal
+region of the horse. According to Portschinsky, it not
+infrequently attacks man
+and then, in all the known
+cases deposits its larvæ
+in the eye, only. This
+is generally done while
+the person is quiet, but
+not during sleep. The
+fly strikes without stopping
+and deposits its larva
+instantaneously. Immediately
+after, the victim
+experiences lancinating
+pains which without intermission
+increase in
+violence. There is an intense
+conjunctivitis and
+if the larvæ are not removed promptly the envelopes
+of the eye are gradually destroyed and the organ
+lost.</p>
+
+<div class="figcenter" style="width: 360px;"><a name="Fig_81" id="Fig_81"></a>
+<a href="images/f081-full.png"><img src="images/f081.png" width="360" height="323" alt="81. Larvæ of Dermatobia cyaniventris. After Blanchard." title="81. Larvæ of Dermatobia cyaniventris. After Blanchard." /></a>
+<span class="caption">81. Larvæ of Dermatobia cyaniventris. After Blanchard.</span>
+</div>
+
+<div class="figcenter" style="width: 125px;"><a name="Fig_82" id="Fig_82"></a>
+<a href="images/f082-full.png"><img src="images/f082.png" width="125" height="519" alt="82. Young larva of
+Dermatobia cyaniventris.
+After Surcouf." title="82. Young larva of
+Dermatobia cyaniventris.
+After Surcouf." /></a>
+<span class="caption">82. Young larva of
+Dermatobia cyaniventris.
+After Surcouf.</span>
+</div>
+
+<p><i>Dermatobia cyaniventris</i>&mdash;This fly (<a href="#Fig_83">fig.&nbsp;83</a>) is widely
+distributed throughout tropical America, and in its
+larval stage is well known as a parasite of man. The
+larvæ (figs. <a href="#Fig_81">81</a>&nbsp;and&nbsp;<a href="#Fig_82">82</a>) which are known as the "ver
+macaque," "torcel," "ver moyocuil" or by several other
+local names, enter the skin and give rise to a boil-like
+swelling, open at the top, and comparable with the swelling
+produced by the warble fly larvæ, in cattle. They
+cause itching and occasional excruciating pain. When
+mature, nearly an inch in length, they voluntarily
+leave their host, drop to the ground and complete their
+development. The adult female is about 12 mm. in
+length. The face is yellow, the frons black with a
+grayish bloom; antennæ yellow, the third segment
+four times as long as the second, the arista pectinate.
+The thorax is bluish black with grayish bloom; the
+abdomen depressed, brilliant metallescent blue with
+violet tinge. The legs are yellowish, the squamæ and
+wings brownish.<span class="pagenum"><a name="Page_116" id="Page_116">[Pg 116]</a></span></p>
+
+<p>The different types of larvæ represented in <a href="#Fig_81">figure 81</a> were formerly
+supposed to belong to different species but Blanchard regards them
+as merely various stages
+of the same species. It
+is only very recently
+that the early stage and
+the method by which
+man becomes infested
+were made known.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_83" id="Fig_83"></a>
+<a href="images/f083-full.png"><img src="images/f083.png" width="500" height="353" alt="83. Dermatobia cyaniventris (×1&frac34;). After Graham-Smith." title="83. Dermatobia cyaniventris (×1&frac34;). After Graham-Smith." /></a>
+<span class="caption">83. Dermatobia cyaniventris (×1&frac34;). After <span title="for Graham-Smith read Manson">Graham-Smith</span>.</span>
+</div>
+
+<div class="figcenter" style="width: 280px;"><a name="Fig_84" id="Fig_84"></a>
+<a href="images/f084-full.png"><img src="images/f084.png" width="280" height="323" alt="84. Mosquito carrying eggs of Dermatobia
+cyaniventris. After Surcouf." title="84. Mosquito carrying eggs of Dermatobia
+cyaniventris. After Surcouf." /></a>
+<span class="caption">84. Mosquito carrying eggs of Dermatobia
+cyaniventris. After Surcouf.</span>
+</div>
+
+<p>About 1900, Blanchard
+observed the presence
+of packets of large-sized
+eggs under the
+abdomen of certain mosquitoes
+from Central
+America; and in 1910,
+Dr. Moralès, of Costa Rica, declared that the Dermatobia deposited
+its eggs directly under the abdomen of the mosquito and that they
+were thus carried to vertebrates.
+Dr. Nunez Tovar observed the
+mosquito carriers of the eggs and
+placing larvæ from this source on
+animals, produced typical tumors
+and reared the adult flies. It
+remained for Surcouf (1913) to
+work out the full details. He
+found that the Dermatobia deposits
+its eggs in packets covered
+by a very viscid substance, on
+leaves. These become attached
+to mosquitoes of the species
+<i>Janthinosoma lutzi</i> (<a href="#Fig_84">fig.&nbsp;84</a>) which
+walk over the leaves. The eggs
+which adhere to the abdomen,
+remain attached and are thus
+transported. The embryo develops,
+but the young larva (<a href="#Fig_82">fig.&nbsp;82</a>) remains in the egg until it has
+opportunity to drop upon a vertebrate fed upon by the mosquito.<span class="pagenum"><a name="Page_117" id="Page_117">[Pg 117]</a></span></p>
+
+
+<h3><a name="Muscidae" id="Muscidae"></a>Muscidæ</h3>
+
+<p>The following <b>Muscidæ</b>, characterized elsewhere, deserve special
+mention under our present grouping of parasitic species. Other
+important species will be considered as facultative parasites.</p>
+
+<p><i>Stomoxys calcitrans</i>, the stable-fly, or the biting house-fly,
+is often confused with <i>Musca domestica</i> and therefore
+is discussed especially in our consideration of the latter
+species as an accidental carrier of disease. Its possible
+relation to the spread of infantile paralysis is also considered
+later.</p>
+
+<div class="figcenter" style="width: 100px;"><a name="Fig_85" id="Fig_85"></a>
+<a href="images/f085-full.png"><img src="images/f085.png" width="100" height="320" alt="85. Larva of
+Auchmeromyia
+luteola. After
+Graham-Smith." title="85. Larva of
+Auchmeromyia
+luteola. After
+Graham-Smith." /></a>
+<span class="caption">85. Larva of
+Auchmeromyia
+luteola. After
+Graham-Smith.</span>
+</div>
+
+<p>The <i>tsetse flies</i>, belonging to the genus <i>Glossina</i>, are
+African species of blood-sucking Muscidæ which have
+attracted much attention because of their rôle in transmitting
+various trypanosome diseases of man and animals.
+They are characterized in Chapter XII and are also
+discussed in connection with the diseases which they
+convey.</p>
+
+<p><a name="Chrysomyia_macellaria" id="Chrysomyia_macellaria"></a><i>Chrysomyia macellaria</i>, (= <i>Compsomyia</i>), the "screw worm"-fly
+is one of the most important species of flies directly affecting man,
+in North America. It is not normally parasitic, however, and hence
+will be considered with other facultative parasites in Chapter IV.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_86" id="Fig_86"></a>
+<a href="images/f086-full.png"><img src="images/f086.png" width="500" height="416" alt="86. Auchmeromyia luteola (×4). After Graham-Smith." title="86. Auchmeromyia luteola (×4). After Graham-Smith." /></a>
+<span class="caption">86. Auchmeromyia luteola (×4). After Graham-Smith.</span>
+</div>
+
+<p><i>Auchmeromyia luteola</i>,
+the Congo floor
+maggot. This is a
+muscid of grewsome
+habits, which has a wide
+distribution throughout
+Africa. The fly (<a href="#Fig_86">fig.&nbsp;86</a>)
+deposits its eggs on the
+ground of the huts of the
+natives. The whitish
+larvæ (<a href="#Fig_85">fig.&nbsp;85</a>) on hatching
+are slightly flattened
+ventrally, and
+each segment bears
+posteriorly three foot-pads
+transversely arranged. At night the larvæ find their way into the
+low beds or couches of the natives and suck their blood. The adult
+flies do not bite man and, as far as known, the larvæ do not play any
+rôle in the transmission of sleeping sickness or other diseases.<span class="pagenum"><a name="Page_118" id="Page_118">[Pg 118]</a></span></p>
+
+<div class="figleft" style="width: 350px;"><a name="Fig_87" id="Fig_87"></a>
+<a href="images/f087-full.png"><img src="images/f087.png" width="350" height="327" alt="87. Cordylobia anthropophaga (×3).
+After Fülleborn." title="87. Cordylobia anthropophaga (×3).
+After Fülleborn." /></a>
+<span class="caption">87. Cordylobia anthropophaga (×3).
+After Fülleborn.</span>
+</div>
+
+<div class="figright" style="width: 300px;"><a name="Fig_88" id="Fig_88"></a>
+<a href="images/f088-full.png"><img src="images/f088.png" width="300" height="409" alt="88. Larva of Cordylobia anthropophaga.
+After Blanchard." title="88. Larva of Cordylobia anthropophaga.
+After Blanchard." /></a>
+<span class="caption">88. Larva of Cordylobia anthropophaga.
+After Blanchard.</span>
+</div>
+
+<p>This habit of blood-sucking by muscid larvæ is usually referred
+to as peculiar to <i>Auchmeromyia luteola</i> but it should be noted that the
+larvæ of <i>Protocalliphora</i> frequent the
+nests of birds and feed upon the
+young. Mr. A.&nbsp;F. Coutant has studied
+especially the life-history and habits
+of <i>P.&nbsp;azurea</i>, whose larvæ he found
+attacking young crows at Ithaca, N.Y.
+He was unable to induce the larvæ to
+feed on man.</p>
+
+<p><i>Cordylobia anthropophaga</i>, (<i>Ochromyia
+anthropophaga</i>), or Tumbu-fly
+(<a href="#Fig_87">fig.&nbsp;87</a>) is an African species whose
+larvæ affect man much as do those of
+<i>Dermatobia cyniventris</i>, of Central and
+South America. The larva (<a href="#Fig_88">fig.&nbsp;88</a>), which is known as "ver du
+Cayor" because it was first observed in Cayor, in Senegambia,
+develops in the skin of man and of various animals, such as dogs,
+cats, and monkeys. It is about 12 mm. in length, and of the form
+of the larvæ of other muscids. Upon the intermediate segments are
+minute, brownish recurved spines which give to the larva its characteristic
+appearance. The life-history is not satisfactorily worked
+out, but Fuller (1914), after reviewing
+the evidence believes that, as a rule, it
+deposits its young in the sleeping places
+of man and animals, whether such be a
+bed, a board, the floor, or the bare ground.
+In the case of babies, the maggots may
+be deposited on the scalp. The minute
+maggots bore their way painlessly into
+the skin. As many as forty parasites
+have been found in one individual and
+one author has reported finding more
+than three hundred in a spaniel puppy.
+Though their attacks are at times extremely
+painful, it is seldom that any
+serious results follow.<span class="pagenum"><a name="Page_119" id="Page_119">[Pg 119]</a></span></p>
+
+
+<h3><a name="The_Siphonaptera_or_Fleas" id="The_Siphonaptera_or_Fleas"></a><span class="smcap">The Siphonaptera or Fleas</span></h3>
+
+<p>The <b>Siphonaptera</b>, or fleas (<a href="#Fig_89">fig.&nbsp;89</a>) are wingless insects, with
+highly chitinized and laterally compressed bodies. The mouth-parts
+are formed for piercing and sucking. Compound eyes are lacking
+but some species possess ocelli. The metamorphosis is complete.</p>
+
+<p>This group of parasites, concerning which little was known until
+recently, has assumed a very great importance since it was learned
+that fleas are the carriers of bubonic plague. Now over four hundred
+species are known. Of these, several species commonly attack man.
+The most common hominoxious species are <i>Pulex irritans</i>, <i>Xenopsylla
+cheopis</i>, <i>Ctenocephalus canis</i>, <i>Ctenocephalus felis</i>, <i>Ceratophyllus
+fasciatus</i> and <i>Dermatophilus penetrans</i>, but many others will feed
+readily on human blood if occasion arises.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_89" id="Fig_89"></a>
+<a href="images/f089-full.png"><img src="images/f089.png" width="500" height="467" alt="89. Xenopsylla cheopis, male (×25). After Jordan and Rothschild." title="89. Xenopsylla cheopis, male (×25). After Jordan and Rothschild." /></a>
+<span class="caption">89. Xenopsylla cheopis, male (×25). After Jordan and Rothschild.</span>
+</div>
+
+<p>We shall treat in this place of the general biology and habits of
+the hominoxious forms and reserve for the systematic section the
+discussion of the characteristics of the different genera.<span class="pagenum"><a name="Page_120" id="Page_120">[Pg 120]</a></span></p>
+
+<p>The most common fleas infesting houses in the Eastern United
+States are the cosmopolitan dog and cat fleas, <i>Ctenocephalus canis</i>
+(<a href="#Fig_90">fig.&nbsp;90</a>) and <i>C. felis</i>. Their life
+cycles will serve as typical.
+These two species have until
+recently been considered as one,
+under the name <i>Pulex serraticeps</i>.
+See <a href="#Fig_92">figure&nbsp;92</a>.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_90" id="Fig_90"></a>
+<a href="images/f090-full.png"><img src="images/f090.png" width="400" height="295" alt="90. Dog flea (×15). After Howard." title="90. Dog flea (×15). After Howard." /></a>
+<span class="caption">90. Dog flea (×15). After Howard.</span>
+</div>
+
+<p>The eggs are oval, slightly
+translucent or pearly white, and
+measure about .5 mm. in their
+long diameter. They are deposited
+loosely in the hairs of
+the host and readily drop off as the animal moves around. Howard
+found that these eggs hatch in one to two days. The larvæ are
+elongate, legless, white, worm-like creatures. They are exceedingly
+active, and avoid the light in every way possible. They
+cast their first skin in from three to seven days and their second
+in from three to four days. They commenced spinning in from
+seven to fourteen days after hatching and the imago appeared
+five days later. Thus in summer, at Washington, the entire life
+cycle may be completed in about two weeks. (cf.&nbsp;fig. <a href="#Fig_91">91</a>,&nbsp;<a href="#Fig_92">92</a>).</p>
+
+<p>Strickland's (1914) studies on the biology of the rat flea, <i>Ceratophyllus
+fasciatus</i>, have so important a general bearing that we shall
+cite them in considerable detail.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_91" id="Fig_91"></a>
+<a href="images/f091-full.png"><img src="images/f091.png" width="500" height="130" alt="91. Larva of Xenopsylla cheopis. After Bacot and Ridewood." title="91. Larva of Xenopsylla cheopis. After Bacot and Ridewood." /></a>
+<span class="caption">91. Larva of Xenopsylla cheopis. After Bacot and Ridewood.</span>
+</div>
+
+<p>He found, to begin with, that there is a marked inherent range
+in the rate of development. Thus, of a batch of seventy-three eggs,
+all laid in the same day and kept together under the same conditions,
+one hatched in ten days; four in eleven days; twenty-five in
+twelve days; thirty-one in thirteen days; ten in fourteen days; one
+in fifteen days; and one in sixteen days. Within these limits the
+duration of the egg period seems to depend mainly on the degree
+of humidity. The incubation period is never abnormally prolonged<span class="pagenum"><a name="Page_121" id="Page_121">[Pg 121]</a></span>
+as in the case of lice, (Warburton) and varying conditions of temperature
+and humidity have practically no effect on the percentage of
+eggs which ultimately hatch.</p>
+
+<p>The same investigator found that the most favorable condition
+for the larva is a low temperature, combined with a high degree of
+humidity; and that the presence of rubbish in which the larva may
+bury itself is essential to its successful development. When larvæ
+are placed in a bottle containing either wood-wool soiled by excrement,
+or with feathers or filter paper covered with dried blood they
+will thrive readily and pupate. They seem to have no choice between
+dried blood and powdered rat feces for food, and also feed
+readily on flea excrement. They possess the curious habit of always
+devouring their molted skins.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_92" id="Fig_92"></a>
+<a href="images/f092-full.png"><img src="images/f092.png" width="500" height="312" alt="92. Head and pronotum of (a) dog flea; (b) of cat flea; (c) of hen flea. After Rothschild.
+(d) Nycteridiphilus (Ischnopsyllus) hexactenus. After Oudemans." title="92. Head and pronotum of (a) dog flea; (b) of cat flea; (c) of hen flea. After Rothschild.
+(d) Nycteridiphilus (Ischnopsyllus) hexactenus. After Oudemans." /></a>
+<span class="caption">92. Head and pronotum of (<i>a</i>)&nbsp;dog flea; (<i>b</i>)&nbsp;of cat flea; (<i>c</i>)&nbsp;of hen flea. After Rothschild.
+(<i>d</i>)&nbsp;Nycteridiphilus (Ischnopsyllus) hexactenus. After Oudemans.</span>
+</div>
+
+<p>An important part of Strickland's experiments dealt with the
+question of duration of the pupal stage under the influence of temperature
+and with the longevity and habits of the adult. In October,
+he placed a batch of freshly formed cocoons in a small dish that was
+kept near a white rat in a deep glass jar in the laboratory. Two
+months later one small and feeble flea had emerged, but no more
+until February, four months after the beginning of the experiment.
+Eight cocoons were then dissected and seven more found to contain
+the imago fully formed but in a resting state. The remainder of<span class="pagenum"><a name="Page_122" id="Page_122">[Pg 122]</a></span>
+the batch was then placed at 70° F. for one night, near a white
+rat. The next day all the cocoons were empty and the fleas were
+found on the white rat.</p>
+
+<p>Thus, temperature greatly influences the duration of the pupal
+period, which in <i>Ceratophyllus fasciatus</i> averages seventeen days.
+Moreover, when metamorphosis is complete a low temperature will
+cause the imago to remain within the cocoon.</p>
+
+<p>Sexually mature and ovipositing fleas, he fed at intervals and kept
+alive for two months, when the experiment was discontinued. In
+the presence of rubbish in which they could bury themselves, unfed
+rat fleas were kept alive for many months, whereas in the absence of
+any such substratum they rarely lived a month. In the former case,
+it was found that the length of life is influenced to some degree by the
+temperature and humidity. In an experiment carried out at 70° F.
+and 45 per cent humidity, the fleas did not live for more than four
+months, while in an experiment at 60° F. and 70 per cent humidity
+they lived for at least seventeen months. There was no indication
+that fleas kept under these conditions sucked moisture from surrounding
+objects, and those kept in bell jars, with an extract of flea-rubbish
+on filter paper, did not live any longer than those which were not so
+supplied.</p>
+
+<p>Curiously enough, although the rat is the normal host of <i>Ceratophyllus
+fasciatus</i>, it was found that when given the choice these fleas
+would feed upon man in preference to rats. However, none of the
+fleas laid eggs unless they fed on rat blood.</p>
+
+<p>The experiments of Strickland on copulation and oviposition in
+the rat flea showed that fleas do not copulate until they are sexually
+mature and that, at least in the case of <i>Ceratophyllus fasciatus</i>, the
+reproductive organs are imperfectly developed for some time (more
+than a week) after emerging from the pupa. When mature, copulation
+takes place soon after the fleas have fed on their true host&mdash;the
+rat&mdash;but not if they have fed on a facultative host only, such as man.
+Copulation is always followed by oviposition within a very short
+time.</p>
+
+<p>The effect of the rat's blood on the female with regard to egg-laying,
+Strickland concludes, is stimulating rather than nutritive,
+as fleas that were without food for many months were observed to
+lay eggs immediately after one feed. Similarly, the male requires
+the stimulus of a meal of rat's blood before it displays any copulatory
+activity.<span class="pagenum"><a name="Page_123" id="Page_123">[Pg 123]</a></span></p>
+
+<p>Mitzmain (1910) has described in detail the act of biting on man,
+as observed in the squirrel flea, <i>Ceratophyllus acutus</i>. "The flea
+when permitted to walk freely on the arm selects a suitable hairy
+space where it ceases abruptly in its locomotion, takes a firm hold
+with the tarsi, projects its proboscis, and prepares to puncture the
+skin. A puncture is drilled by the pricking epipharynx, the saw-tooth
+mandibles supplementing the movement by lacerating the
+cavity formed. The two organs of the rostrum work alternately,
+the middle piece boring, while the two lateral elements execute a
+sawing movement. The mandibles, owing to their basal attachments,
+are, as is expressed by the advisory committee on plague
+investigations in India (<i>Journal of Hygiene</i>, vol. 6, No. 4, p. 499),
+'capable of independent action, sliding up and down but maintaining
+their relative positions and preserving the lumen of the aspiratory
+channel.' The labium doubles back, the V-shaped groove of this
+organ guiding the mandibles on either side."</p>
+
+<p>"The action of the proboscis is executed with a forward movement
+of the head and a lateral and downward thrust of the entire body.
+As the mouth-parts are sharply inserted, the abdomen rises simultaneously.
+The hind and middle legs are elevated, resembling oars.
+The forelegs are doubled under the thorax, the tibia and tarsi resting
+firmly on the epidermis serve as a support for the body during the
+feeding. The maxillary palpi are retracted beneath the head and
+thorax. The labium continues to bend, at first acting as a sheath
+for the sawing mandibles, and as these are more deeply inserted, it
+bends beneath the head with the elasticity of a bow, forcing the
+mandibles into the wound until the maxillæ are embedded in the skin
+of the victim. When the proboscis is fully inserted, the abdomen
+ceases for a time its lateral swinging."</p>
+
+<p>"The acute pain of biting is first felt when the mandibles have
+not quite penetrated and subsequently during each distinct movement
+of the abdomen. The swinging of the abdomen gradually
+ceases as it becomes filled with blood. The sting of the biting
+gradually becomes duller and less sensitive as feeding progresses.
+The movements of the elevated abdomen grow noticeably feebler
+as the downward thrusts of the springy bow-like labium becomes less
+frequent."</p>
+
+<p>"As the feeding process advances one can discern through the
+translucent walls of the abdomen a constant flow of blood, caudally
+from the pharynx, accompanied by a peristaltic movement. The<span class="pagenum"><a name="Page_124" id="Page_124">[Pg 124]</a></span>
+end of the meal is signified in an abrupt manner. The flea shakes
+its entire body, and gradually withdraws its proboscis by lowering
+the abdomen and legs and violently twisting the head."</p>
+
+<p>"When starved for several days the feeding of the rat fleas is
+conducted in a rather vigorous manner. As soon as the proboscis
+is buried to the full length the abdomen is raised and there ensues a
+gradual lateral swaying motion, increasing the altitude of the raised
+end of the abdomen until it assumes the perpendicular. The flea is
+observed at this point to gain a better foothold by advancing the
+fore tarsi, and then, gradually doubling back the abdomen, it turns
+with extreme agility, nearly touching with its dorsal side the skin
+of the hand upon which it is feeding. Meanwhile, the hungry parasite
+feeds ravenously."</p>
+
+<p>"It is interesting to note the peculiar nervous action which the
+rodent fleas exhibit immediately when the feeding process is completed
+or when disturbed during the biting. Even while the rostrum
+is inserted to the fullest the parasite shakes its head spasmodically;
+in a twinkling the mouth is withdrawn and then the flea hops away."</p>
+
+<p>A habit of fleas which we shall see is of significance in considering
+their agency in the spread of bubonic plague, is that of ejecting blood
+from the anus as they feed.</p>
+
+<p>Fleas are famous for their jumping powers, and in control measures
+it is of importance to determine their ability along this line. It is
+often stated that they can jump about four inches, or, according to
+the Indian Plague Commission <i>Xenopsylla cheopis</i> cannot hop farther
+than five inches. Mitzmain (1910) conducted some careful experiments
+in which he found that the human flea, <i>Pulex irritans</i>, was
+able to jump as far as thirteen inches on a horizontal plane. The
+mean average of five specimens permitted to jump at will was seven
+and three-tenths inches. The same species was observed to jump
+perpendicularly to a height of at least seven and three-fourths inches.
+Other species were not able to equal this record.</p>
+
+<p>The effect of the bite of fleas on man varies considerably according
+to the individual susceptibility. According to Patton and Cragg,
+this was borne out in a curious manner by the experiments of Chick
+and Martin. "In these, eight human hosts were tried; in seven,
+little or no irritation was produced, while in one quite severe inflammation
+was set up around each bite." Of two individuals, equally
+accustomed to the insects, going into an infested room, one may be
+literally tormented by them while the other will not notice them.<span class="pagenum"><a name="Page_125" id="Page_125">[Pg 125]</a></span>
+Indeed it is not altogether a question of susceptibility, for fleas seem
+to have a special predilection for certain individuals. The typical
+itching wheals produced by the bites are sometimes followed, especially
+after scratching, by inflammatory papules.</p>
+
+<p>The itching can be relieved by the use of lotions of carbolic acid
+(2-3 per cent), camphor, menthol lotion, or carbolated vaseline.
+If forced to sleep in an infested room, protection from attacks can
+be in a large measure gained by sprinkling pyrethrum, bubach, or
+California insect powder between the sheets. The use of camphor,
+menthol, or oil of eucalyptus, or oil of pennyroyal is also said to afford
+protection to a certain extent.</p>
+
+<p>In the Eastern United States the occurrence of fleas as household
+pests is usually due to infested cats and dogs which have the run of
+the house. We have seen that the eggs are not attached to the host
+but drop to the floor when they are laid. Verrill, cited by Osborn,
+states that on one occasion he was able to collect fully a teaspoonful
+of eggs from the dress of a lady in whose lap a half-grown kitten had
+been held for a short time. Patton and Cragg record seeing the
+inside of a hat in which a kitten had spent the night, so covered with
+flea eggs that it looked "as if it had been sprinkled with sugar from
+a sifter." It is no wonder that houses in which pets live become
+overrun with the fleas.</p>
+
+<p>One of the first control measures, then, consists in keeping such
+animals out of the house or in rigorously keeping them free from fleas.
+The latter can best be accomplished by the use of strong tar soap
+or Armour's "Flesope," which may be obtained from most druggists.
+The use of a three per cent solution of creolin, approximately four
+teaspoonfuls to a quart of warm water, has also been recommended.
+While this is satisfactory in the case of dogs, it is liable to sicken cats,
+who will lick their fur in an effort to dry themselves. Howard
+recommends thoroughly rubbing into the fur a quantity of pyrethrum
+powder. This partially stupifies the fleas which should be promptly
+swept up and burned.</p>
+
+<p>He also recommends providing a rug for the dog or cat to sleep
+on and giving this rug a frequent shaking and brushing, afterwards
+sweeping up and burning the dust thus removed.</p>
+
+<p>Since the larvæ of fleas are very susceptible to exposure, the use
+of bare floors, with few rugs, instead of carpets or matting, is to be
+recommended. Thorough sweeping, so as to allow no accumulation
+of dust in cracks and crevices will prove efficient. If a house is once<span class="pagenum"><a name="Page_126" id="Page_126">[Pg 126]</a></span>
+infested it may be necessary to thoroughly scrub the floors with hot
+soapsuds, or to spray them with gasoline. If the latter method is
+adopted, care must be taken to avoid the possibility of fire.</p>
+
+<p>To clear a house of fleas Skinner recommends the use of flake
+naphthalene. In a badly infested house he took one room at a time,
+scattering on the floor five pounds of flake naphthalene, and closed
+it for twenty-four hours. It proved to be a perfect and effectual
+remedy and very inexpensive, as the naphthalene could be swept up
+and transferred to other rooms. Dr. Skinner adds, "so far as I am
+concerned, the flea question is solved and if I have further trouble
+I know the remedy. I intend to keep the dog and cat."</p>
+
+<p>The late Professor Slingerland very effectively used hydrocyanic
+acid gas fumigation in exterminating fleas in houses. In one case,
+where failure was reported, he found on investigation that the house
+had become thoroughly reinfested from pet cats, which had been left
+untreated. Fumigation with sulphur is likewise efficient.</p>
+
+<p>The fact that adult fleas are usually to be found on the floor,
+when not on their hosts, was ingeniously taken advantage of by
+Professor S. H. Gage in ridding an animal room at Cornell University
+of the pests. He swathed the legs of a janitor with sticky fly-paper
+and had him walk back and forth in the room. Large numbers of
+the fleas were collected in this manner.</p>
+
+<p>In some parts of the southern United States hogs are commonly
+infested and in turn infest sheds, barns and even houses. Mr. H. E.
+Vick informs us that it is a common practice to turn sheep into barn-lots
+and sheds in the spring of the year to collect in their wool, the
+fleas which abound in these places after the hogs have been turned
+out.</p>
+
+<p>It is a common belief that adult fleas are attracted to fresh meat
+and that advantage of this can be taken in trapping them. Various
+workers, notably Mitzman (1910), have shown that there is no basis
+for such a belief.</p>
+
+
+<p><a name="The_true_chiggers" id="The_true_chiggers"></a><b>The true chiggers</b>&mdash;The chigoes, or true chiggers, are the most
+completely parasitic of any of the fleas. Of the dozen or more known
+species, one commonly attacks man. This is <i>Dermatophilus penetrans</i>,
+more commonly known as <i>Sarcopsylla penetrans</i> or <i>Pulex penetrans</i>.</p>
+
+<p>This species occurs in Mexico, the West Indies, Central and South
+America. There are no authentic records of its occurrence in the
+United States although, as Baker has pointed out, there is no reason<span class="pagenum"><a name="Page_127" id="Page_127">[Pg 127]</a></span>
+why it should not become established in Florida and Texas. It is
+usually believed that Brazil was its original home. Sometime about
+the middle of the nineteenth century it was introduced into West
+Africa and has spread across that continent.</p>
+
+<p>The males and the immature females of <i>Dermatophilus penetrans</i>
+(<a href="#Fig_93">fig.&nbsp;93</a>) closely resemble those of other fleas. They are very active
+little brown insects about 1-1.2 mm. in size, which live in the dust of
+native huts and stables, and in dry, sandy soil. In such places they
+often occur in enormous numbers and become a veritable plague.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_93" id="Fig_93"></a>
+<a href="images/f093-full.png"><img src="images/f093.png" width="400" height="283" alt="93. Dermatophilus penetrans. Much enlarged. After Karsten." title="93. Dermatophilus penetrans. Much enlarged. After Karsten." /></a>
+<span class="caption">93. Dermatophilus penetrans. Much enlarged. After Karsten.</span>
+</div>
+
+<p>They attack not only man but various animals. According to
+Castellani and Chalmers, "Perhaps the most noted feature is the way
+in which it attacks pigs. On the Gold Coast it appeared to be largely
+kept in existence by these animals. It is very easily captured in
+the free state by taking a little pig with a pale abdomen, and placing
+it on its back on the ground on which infected pigs are living. After
+watching a few moments, a black speck will appear on the pig's
+abdomen, and quickly another and another. These black specks are
+jiggers which can easily be transferred to a test tube. On examination
+they will be found to be males and females in about equal
+numbers."</p>
+
+<p>Both the males and females suck blood. That which characterizes
+this species as distinguished from other fleas attacking man is that
+when the impregnated female attacks she burrows into the skin
+and there swells until in a few days she has the size and appearance of
+a small pea (<a href="#Fig_94">fig.&nbsp;94</a>). Where they are abundant, hundreds of the<span class="pagenum"><a name="Page_128" id="Page_128">[Pg 128]</a></span>
+pests may attack a single individual (<a href="#Fig_95">fig.&nbsp;95</a>). Here they lie with the
+apex of the abdomen blocking the opening. According to Fülleborn
+(1908) they do not
+penetrate beneath the
+epidermis. The eggs are
+not laid in the flesh of
+the victim, as is sometimes
+stated, but are
+expelled through this
+opening. The female
+then dies, withers and
+falls away or is expelled
+by ulceration. According
+to Brumpt, she first
+quits the skin and then,
+falling to the ground,
+deposits her eggs. The
+subsequent development
+in so far as known,
+is like that of other fleas.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_94" id="Fig_94"></a>
+<a href="images/f094-full.png"><img src="images/f094.png" width="350" height="266" alt="94. Dermatophilus penetrans, gravid female. After Moniez." title="94. Dermatophilus penetrans, gravid female. After Moniez." /></a>
+<span class="caption">94. Dermatophilus penetrans, gravid female. After Moniez.</span>
+</div>
+
+<div class="figcenter" style="width: 250px;"><a name="Fig_95" id="Fig_95"></a>
+<a href="images/f095-full.png"><img src="images/f095.png" width="250" height="334" alt="95. Chiggers in the sole of foot of man. Manson&#39;s
+Tropical Diseases. Permission of Cassell and Co." title="95. Chiggers in the sole of foot of man. Manson&#39;s
+Tropical Diseases. Permission of Cassell and Co." /></a>
+<span class="caption">95. Chiggers in the sole of foot of man. Manson&#39;s
+Tropical Diseases. Permission of Cassell and Co.</span>
+</div>
+
+<div class="figleft" style="width: 250px;"><a name="Fig_96" id="Fig_96"></a>
+<a href="images/f096-full.png"><img src="images/f096.png" width="250" height="327" alt="96. Echidnophaga gallinacea." title="96. Echidnophaga gallinacea." /></a>
+<span class="caption">96. Echidnophaga gallinacea.</span>
+</div>
+
+<p>The chigoe usually
+enters between the toes,
+the skin about the roots
+of the nails, or the soles<span class="pagenum"><a name="Page_129" id="Page_129">[Pg 129]</a></span>
+of the feet, although it may attack other parts of the body. Mense
+records the occurrence in folds of the epidermis, as in the neighborhood
+of the anus. They give rise to irritation
+and unless promptly and aseptically removed
+there often occurs pus formation and the
+development of a more or less serious abscess.
+Gangrene and even tetanus may ensue.</p>
+
+<p>Treatment consists in the careful removal
+of the insect, an operation more easily accomplished
+a day or two after its entrance, than
+at first, when it is unswollen. The ulcerated
+point should then be treated with weak carbolic
+acid, or tincture of iodine, or dusted
+thoroughly with an antiseptic powder.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_97" id="Fig_97"></a>
+<a href="images/f097-full.png"><img src="images/f097.png" width="350" height="272" alt="97. Echidnophaga gallinacea infesting head of chicken. After Enderlein." title="97. Echidnophaga gallinacea infesting head of chicken. After Enderlein." /></a>
+<span class="caption">97. Echidnophaga gallinacea infesting head of chicken. After Enderlein.</span>
+</div>
+
+<p>Castellani and Chalmers recommend as
+prophylactic measures, keeping the house clean and keeping pigs,
+poultry, and cattle away therefrom. "High boots should be used,
+and especial care should be taken not to go to a ground floor bathroom
+with bare feet. The feet, especially the toes, and under the
+nails, should be carefully examined every morning to see if any black
+dots can be discovered, when the jigger should be at once removed,
+and in this way suppuration will be prevented. It is advisable,<span class="pagenum"><a name="Page_130" id="Page_130">[Pg 130]</a></span>
+also, to sprinkle the floors with carbolic lotion, Jeyes' fluid, or with
+pyrethrum powder, or with a strong infusion of native tobacco, as
+recommended by Law and Castellani."</p>
+
+<p><i>Echidnophaga gallinacea</i> (<a href="#Fig_96">fig.&nbsp;96</a>) is a widely distributed Hectopsyllid
+attacking poultry (<a href="#Fig_97">fig.&nbsp;97</a>). It occurs in the Southern and Southwestern
+United States and has been occasionally reported as attacking
+man, especially children. It is less highly specialized than
+<i>Dermatophilus penetrans</i>, and does not ordinarily cause serious
+trouble in man.<span class="pagenum"><a name="Page_131" id="Page_131">[Pg 131]</a></span></p>
+
+
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="CHAPTER_IV" id="CHAPTER_IV"></a>CHAPTER IV</h2>
+
+<h2>ACCIDENTAL OR FACULTATIVE PARASITES</h2>
+
+
+<p>In addition to the many species of Arthropods which are normally
+parasitic on man and animals, there is a considerable number of those
+which may be classed as <i>accidental</i> or <i>facultative</i> parasites.</p>
+
+<p>Accidental or facultative parasites are species which are normally
+free-living, but which are able to exist as parasites when accidentally
+introduced into the body of man or other animal. A wide range of
+forms is included under this grouping.</p>
+
+
+<h3><a name="Acarina" id="Acarina"></a><span class="smcap">Acarina</span></h3>
+
+<p>A considerable number of mites have been reported as accidental
+or even normal, endoparasites of man, but the authentic cases are
+comparatively few.</p>
+
+<p>In considering such reports it is well to keep in mind von Siebold's
+warning that in view of the universal distribution of mites one should
+be on his guard. In vessels in which animal and other organic
+fluids and moist substances gradually dry out, mites are very abundantly
+found. If such vessels are used without very careful preliminary
+cleaning, for the reception of evacuations of the sick, or for the
+reception of parts removed from the body, such things may be readily
+contaminated by mites, which have no other relation whatever to
+them.</p>
+
+<p>Nevertheless, there is no doubt but that certain mites, normally
+free-living, have occurred as accidental parasites of man. Of these
+the most commonly met with is <i>Tyroglyphus siro</i>, the cheese-mite.</p>
+
+<p><i>Tyroglyphus siro</i> is a small mite of a whitish color. The male
+measures about 500µ long by 250µ wide, the female slightly larger.
+They live in cheese of almost any kind, especially such as is a little
+decayed. "The individuals gather together in winter in groups or
+heaps in the hollows and chinks of the cheese and there remain
+motionless. As soon as the temperature rises a little, they gnaw
+away at the cheese and reduce it to a powder. The powder is composed
+of excrement having the appearance of little grayish microscopic
+balls; eggs, old and new, cracked and empty; larvæ, nymphs, and
+perfect mites, cast skins and fragments of cheese, to which must be
+added numerous spores of microscopic fungi."&mdash;Murray.<span class="pagenum"><a name="Page_132" id="Page_132">[Pg 132]</a></span></p>
+
+<p><i>Tyroglyphus siro</i>, and related species, have been found many
+times in human feces, under conditions which preclude the explanation
+that the contamination occurred outside of the body. They
+have been supposed to be the cause of dysentery, or diarrh&oelig;a, and
+it is probable that the <i>Acarus dysenteriæ</i> of Linnæus, and Latreille,
+was this species. However, there is little evidence that the mites
+cause any noteworthy symptoms, even when taken into the body
+in large numbers.</p>
+
+<p><i>Histiogaster spermaticus</i> (<a href="#Fig_152">fig.&nbsp;152</a>) is a Tyroglyphid mite which
+was reported by Trouessart (1902) as having been found in a cyst
+in the groin, adherent to the testis. When the cyst was punctured,
+it yielded about two ounces of opalescent fluid containing spermatozoa
+and numerous mites in all stages of development. The evidence
+indicated that a fecundated female mite had been introduced into
+the urethra by means of an unclean catheter. Though Trouessart
+reported the case as that of a Sarcoptid, Banks places the genus
+<i>Histiogaster</i> with the Tyroglyphidæ. He states that our species
+feeds on the oyster-shell bark louse, possibly only after the latter is
+dead, and that in England a species feeds within decaying reeds.</p>
+
+<p><i>Nephrophages sanguinarius</i> is a peculiarly-shaped, angular mite
+which was found by Miyake and Scriba (1893) for eight successive
+days in the urine of a Japanese suffering from fibrinuria. Males,
+.117 mm. long by .079 mm. wide, females .36 mm. by. 12 mm.,
+and eggs were found both in the spontaneously emitted urine and in
+that drawn by means of a catheter. All the mites found were dead.
+The describers regarded this mite as a true endoparasite, but it is
+more probable that it should be classed as an accidental parasite.</p>
+
+
+<h3><a name="Myriapoda" id="Myriapoda"></a><span class="smcap">Myriapoda</span></h3>
+
+<p>There are on record a number of cases of myriapods occurring as
+accidental parasites of man. The subject has been treated in detail
+by Blanchard (1898 and 1902), who discussed forty cases. Since
+then at least eight additions have been made to the list.</p>
+
+<p>Neveau-Lamaire (1908) lists thirteen species implicated, representing
+eight different genera. Of the <i>Chilognatha</i> there are three,
+<i>Julus terrestris</i>, <i>J. londinensis</i> and <i>Polydesmus complanatus</i>. The
+remainder are <i>Chilopoda</i>, namely, <i>Lithobius forficatus</i>, <i>L. malenops</i>,
+<i>Geophilus carpophagus</i>, <i>G. electricus</i>, <i>G. similis</i>, <i>G. cephalicus</i>, <i>Scutigera
+coleoptrata</i>, <i>Himantarium gervaisi</i>, <i>Chætechelyne vesuviana</i> and
+<i>Stigmatogaster subterraneus</i>.<span class="pagenum"><a name="Page_133" id="Page_133">[Pg 133]</a></span></p>
+
+<p>The majority of the cases relate to infestation of the nasal fossæ,
+or the frontal sinus, but intestinal infestation also occurs and there
+is one recorded case of the presence of a species in <i>Julus</i> (<a href="#Fig_13">fig.&nbsp;13</a>) in
+the auditory canal of a child.</p>
+
+<p>In the nose, the myriapods have been known to live for months
+and according to some records, even for years. The symptoms
+caused by their presence are inflammation, with or without increased
+flow of mucus, itching, more or less intense headache, and at times
+general symptoms such as vertigo, delirium, convulsions, and the
+like. These symptoms disappear suddenly when the parasites are
+expelled.</p>
+
+<p>In the intestine of man, myriapods give rise to obscure symptoms
+suggestive of infestation by parasitic worms. In a case reported by
+Verdun and Bruyant (1912), a child twenty months of age had been
+affected for fifteen days by digestive disturbances characterized by
+loss of appetite, nausea and vomiting. The latter had been particularly
+pronounced for three days, when there was discovered in the
+midst of the material expelled a living myriapod of the species
+<i>Chætechelyne vesuviana</i>. Anthelminthics had been administered
+without result. In some of the other cases, the administration of
+such drugs had resulted in the expulsion of the parasite through the
+anus.</p>
+
+<p>One of the extreme cases on record is that reported by Shipley
+(1914). Specimens of <i>Geophilus gorizensis</i> (= <i>G. subterraneus</i>)
+"were vomited and passed by a woman of 68 years of age. Some of
+the centipedes emerged through the patient's nose, and it must be
+mentioned that she was also suffering from a round worm. One of
+her doctors was of the opinion that the centipedes were certainly
+breeding inside the lady's intestines, and as many as seven or eight,
+sometimes more, were daily leaving the alimentary canal."</p>
+
+<p>"According to her attendant's statements those centipedes had
+left the body in some hundreds during a period of twelve or eighteen
+months. Their presence produced vomiting and some hæmatemesis,
+and treatment with thymol, male-fern and turpentine had no effect
+in removing the creatures."</p>
+
+<p>The clinical details, as supplied by Dr. Theodore Thompson were
+as follows:</p>
+
+<p>"Examined by me July, 1912, her tongue was dry and glazed.
+There was bleeding taking place from the nose and I saw a living
+centipede she had just extracted from her nostril. Her heart, lungs<span class="pagenum"><a name="Page_134" id="Page_134">[Pg 134]</a></span>
+and abdomen appeared normal. She was not very wasted, and did
+not think she had lost much flesh, nor was there any marked degree
+of anemia."</p>
+
+<p>Shipley gives the following reasons for believing it impossible
+that these centipedes could have multiplied in the patient's intestine.
+"The breeding habits of the genus <i>Geophilus</i> are peculiar, and ill
+adapted for reproducing in such a habitat. The male builds a small
+web or nest, in which he places his sperm, and the female fertilizes
+herself from this nest or web, and when the eggs are fertilized they
+are again laid in a nest or web in which they incubate and in two or
+three weeks hatch out. The young <i>Geophilus</i> differ but very little
+from the adult, except in size. It is just possible, but improbable,
+that a clutch of eggs had been swallowed by the host when eating
+some vegetables or fruit, but against this is the fact that the <i>Geophilus</i>
+does not lay its eggs upon vegetables or fruit, but upon dry wood or
+earth. The egg-shell is very tough and if the eggs had been swallowed
+the egg-shells could certainly have been detected if the dejecta were
+examined. The specimens of the centipede showed very little signs
+of being digested, and it is almost impossible to reconcile the story
+of the patient with what one knows of the habits of the centipedes."</p>
+
+<p>In none of the observed cases have there been any clear indications
+as to the manner of infestation. It is possible that the myriapods
+have been taken up in uncooked fruit or vegetables.</p>
+
+
+<h3><a name="Lepidopterous_Larvae" id="Lepidopterous_Larvae"></a><span class="smcap">Lepidopterous Larvæ</span></h3>
+
+
+<p><b>Scholeciasis</b>&mdash;Hope (1837) brought together six records of infestation
+of man by lepidopterous larvæ and proposed to apply the name
+scholeciasis to this type of parasitism. The clearest case was that
+of a young boy who had repeatedly eaten raw cabbage and who
+vomited larvæ of the cabbage butterfly, <i>Pieris brassicæ</i>. Such cases
+are extremely rare, and there are few reliable data relative to the
+subject. In this connection it may be noted that Spuler (1906) has
+described a moth whose larvæ live as ectoparasites of the sloth.</p>
+
+
+<h3><a name="Coleoptera" id="Coleoptera"></a><span class="smcap">Coleoptera</span></h3>
+
+
+<p><b>Canthariasis</b>&mdash;By this term Hope designated instances of accidental
+parasitism by the larvæ or adults of beetles. Reports of
+such cases are usually scouted by parasitologists but there seems no
+good basis for wholly rejecting them. Cobbold refers to a half
+dozen cases of accidental parasitism by the larvæ of <i>Blaps mortisaga</i>.<span class="pagenum"><a name="Page_135" id="Page_135">[Pg 135]</a></span>
+In one of these cases upwards of 1200 larvæ and several perfect
+insects were said to have been passed <i>per annum</i>. French (1905)
+reports the case of a man
+who for a considerable period
+voided adult living beetles
+of the species <i>Nitidula
+bipustulata</i>. Most of the
+other cases on record relate
+to the larvæ of <i>Dermestidæ</i>
+(larder beetles <i>et al.</i>) or
+<i>Tenebrionidæ</i> (meal infesting species). Infestation probably occurs
+through eating raw or imperfectly cooked foods containing eggs or
+minute larvæ of these insects.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_98" id="Fig_98"></a>
+<a href="images/f098-full.png"><img src="images/f098.png" width="450" height="181" alt="98. Larva of Piophila casei. Caudal aspect of larva.
+Posterior stigmata." title="98. Larva of Piophila casei. Caudal aspect of larva.
+Posterior stigmata." /></a>
+<span class="caption">98. Larva of Piophila casei. Caudal aspect of larva.
+Posterior stigmata.</span>
+</div>
+
+<p>Brumpt cites a curious case of accidental parasitism by a coleopterous
+larva belonging to the genus <i>Necrobia</i>. This larva was extracted
+from a small tumor, several millimeters long, on the surface of the
+conjunctiva of the eye. The larvæ of this genus ordinarily live in
+decomposing flesh and cadavers.</p>
+
+
+<h3><a name="Dipterous_Larvae" id="Dipterous_Larvae"></a><span class="smcap">Dipterous Larvæ</span></h3>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_99" id="Fig_99"></a>
+<a href="images/f099-full.png"><img src="images/f099.png" width="500" height="380" alt="99. Piophila casei. After Graham-Smith." title="99. Piophila casei. After Graham-Smith." /></a>
+<span class="caption">99. Piophila casei. After Graham-Smith.</span>
+</div>
+
+
+<p><b>Myasis</b>&mdash;By this term (spelled also myiasis, and myiosis), is
+meant parasitism by dipterous larvæ. Such parasitism may be
+normal, as in the cases already described under the heading parasitic
+Diptera, or it may be facultative, due to free-living larvæ being
+accidentally introduced
+into wounds or the body-cavities
+of man. Of this
+latter type, there is a
+multitude of cases on
+record, relating to comparatively
+few species.
+The literature of the subject,
+like that relating
+to facultative parasitism
+in general, is unsatisfactory,
+for most of the
+determinations of species
+have been very loose.
+Indeed, so little has been known regarding the characteristics of
+the larvæ concerned that in many instances they could not be exactly<span class="pagenum"><a name="Page_136" id="Page_136">[Pg 136]</a></span>
+determined. Fortunately, several workers have undertaken comparative
+studies along this line. The most comprehensive publication
+is that of Banks (1912), entitled "The structure of certain dipterous
+larvæ, with particular reference to those in human food."</p>
+
+<p>Without attempting an exhaustive list, we shall discuss here the
+more important species of Diptera whose larvæ are known to cause
+myasis, either external or internal. The following key will serve
+to determine those most likely to be encountered. The writers
+would be glad to examine specimens not readily identifiable, if
+accompanied by exact data relative to occurrence.</p>
+
+<div class="blockquot"><div class="hanging">
+<p><i>a.</i> Body more or less flattened, depressed; broadest in the middle, each segment
+with dorsal, lateral, and ventral fleshy processes, of which the laterals,
+at least, are more or less spiniferous (<a href="#Fig_101">fig.&nbsp;101</a>). <i>Fannia</i> (=&nbsp;<i>Homalomyia</i>).</p>
+
+<div class="hanging">
+<p>In <i>F.&nbsp;canicularis</i> the dorsal processes are nearly as long as the laterals;
+in <i>F.&nbsp;scalaris</i> the dorsal processes are short spinose tubercles.</p>
+</div>
+
+<p><i>aa.</i> Body cylindrical, or slender conical tapering toward the head; without
+fleshy lateral processes (<a href="#Fig_105">fig.&nbsp;105</a>).</p>
+
+<p><i>b.</i> With the posterior stigmata at the end of shorter or longer tubercles, or if not
+placed upon tubercles, then not in pit; usually without a "marginal button"
+and without a chitinous ring surrounding the three slits; the slits narrowly
+or broadly oval, not bent (<a href="#Fig_171">fig.&nbsp;171&nbsp;i</a>). <i>Acalyptrate muscidæ</i> and some species
+of <i>Anthomyiidæ</i>. To this group belong the cheese skipper (<i>Piophila casei</i>,
+figs. <a href="#Fig_98">98</a>,&nbsp;<a href="#Fig_99">99</a>), the pomace-fly (<i>Drosophila ampelophila</i>), the apple maggot
+(<i>Rhagoletis pomonella</i>), the cherry fruit fly (<i>Rhagoletis cingulata</i>), the small
+dung fly (<i>Sepsis violacea</i>, <a href="#Fig_170">fig.&nbsp;170</a>), the beet leaf-miner (<i>Pegomyia vicina</i>,
+<a href="#Fig_171">fig.&nbsp;171&nbsp;i</a>), the cabbage, bean and onion maggots (<i>Phorbia</i> spp.) et.&nbsp;al.</p>
+
+<p><i>bb.</i> Posterior stigmata of various forms, if the slits are narrowly oval (<a href="#Fig_171">fig.&nbsp;171</a>)
+then they are surrounded by a chitin ring which may be open ventro-mesally.</p>
+
+<p><i>c.</i> Integument leathery and usually strongly spinulose; larvæ hypodermatic or
+endoparasitic. Bot flies (<a href="#Fig_171">fig.&nbsp;171, f, g, k</a>).&mdash;<i>Oestridæ</i></p>
+
+<p><i>cc.</i> Integument not leathery and (except in <i>Protocalliphora</i>) spinulæ restricted
+to transverse patches near the incisures of the segments.</p>
+
+<p><i>d.</i> The stigmal plates in a pit; the lip-like margin of the pit with a number of
+fleshy tubercles; <span title="insert &quot;ring&quot; after &quot;chitin&quot;"><a name="AC_7" id="AC_7"></a>chitin</span> of the stigma not complete; open ventro-mesally,
+button absent (<a href="#Fig_171">fig.&nbsp;171&nbsp;e</a>). Flesh flies.&mdash;<i>Sarcophaga</i></p>
+
+<p><i>dd.</i> Stigmata not in a pit.</p>
+
+<p><i>e.</i> The chitin ring open ventra-mesally; button absent (<a href="#Fig_171">fig.&nbsp;171&nbsp;c</a>). Screw-worm
+fly. <i>Chrysomyia</i></p>
+
+<p><i>ee.</i> The chitin ring closed.</p>
+
+<p><i>f.</i> Slits of the posterior stigmata straight; marginal "button" present (<a href="#Fig_171">fig.&nbsp;171&nbsp;b</a>);
+two distinct mouth hooks, fleshy tubercles around the anal area. <i>Phormia</i>
+(<a href="#Fig_171">fig.&nbsp;171&nbsp;f</a>), <i>Lucilia</i> and <i>Calliphora</i> (<a href="#Fig_172">fig.&nbsp;172, a,&nbsp;b</a>), <i>Protocalliphora</i> (<a href="#Fig_171">fig.&nbsp;171, j</a>),
+<i>Cynomyia</i> (<a href="#Fig_171">fig.&nbsp;171, a</a>). Blow flies, bluebottle flies. <i>Calliphorinæ</i><span class="pagenum"><a name="Page_137" id="Page_137">[Pg 137]</a></span></p>
+
+<p><i>ff.</i> Slits of the posterior stigmata sinuous or bent. Subfamily Muscinæ.</p>
+
+<p><i>g.</i> Slits of the posterior stigmata bent; usually two mouth hooks. <i>Muscina
+stabulans</i> (<a href="#Fig_171">fig.&nbsp;171, l</a>), <i>Muscina similis</i>, <i>Myiospila <span title="for meditatunda read meditabunda"><a name="AC_8" id="AC_8"></a>meditatunda</span></i> (<a href="#Fig_172">fig.&nbsp;172, i</a>),
+and some of the higher <i>Anthomyiidæ</i>.</p>
+
+<p><i>gg.</i> Slits of the posterior stigmata sinuous; mouth hooks usually consolidated
+into one. The house-fly (<i>Musca domestica</i> <a href="#Fig_171">fig.&nbsp;171, d</a>), the stable fly
+(<i>Stomoxys calcitrans</i>), the horn fly (<i>Lyperosia irritans</i>), <i>Pyrellia</i>, <i>Pseudopyrellia</i>,
+<i>Morellia</i>, <i>Mesembrina</i>. <i>Polietes</i>, et. al. (<a href="#Fig_172">fig.&nbsp;172</a> in part).</p>
+</div></div>
+
+<p><i>Eristalis</i>&mdash;The larvæ of <i>Eristalis</i> are the so-called rat-tailed maggots,
+which develop in foul water. In a few instances these larvæ
+have been known to pass through the human alimentary canal
+uninjured. Hall and Muir (1913) report the case of a boy five years
+of age, who had been ailing for ten weeks and who was under treatment
+for indigestion and chronic constipation. For some time he
+had vomited everything he ate. On administration of a vermifuge
+he voided one of the rat-tailed maggots of <i>Eristalis</i>. He admitted
+having drunk water from a ditch full of all manner of rotting matter.
+It was doubtless through this that he became infested. It is worth
+noting that the above described symptoms may have been due to
+other organisms or substances in the filthy water.</p>
+
+<p><a name="Piophila_casei" id="Piophila_casei"></a><i>Piophila casei</i>, the cheese-fly (<a href="#Fig_99">fig.&nbsp;99</a>), deposits its eggs not only
+in old cheeses, but on ham, bacon, and other fats. The larvæ (<a href="#Fig_98">fig.&nbsp;98</a>)
+are the well-known cheese skippers, which sometimes occur in great
+abundance on certain kinds of cheese. Indeed, some people have
+a comfortable theory that such infested cheese is especially good.
+Such being the case, it is small wonder that this species has been
+repeatedly reported as causing intestinal myasis. Thebault (1901)
+describes the case of a girl who, shortly after consuming a large piece
+of badly infested cheese, became ill and experienced severe pains
+in the region of the navel. Later these extended through the entire
+alimentary canal, the excrement was mixed with blood and she
+suffered from vertigo and severe headaches. During the four following
+days the girl felt no change, although the excretion of the blood
+gradually diminished and stopped. On the fourth day she voided
+two half-digested larvæ and, later, seven or eight, of which two were
+alive and moving.</p>
+
+<p>That these symptoms may be directly attributed to the larvæ,
+or "skippers," has been abundantly shown by experimental evidence.
+Portschinsky cites the case of a dog fed on cheese containing the
+larvæ. The animal suffered much pain and its excrement contained
+blood. On <i>post mortem</i> it was found that the small intestine throughout<span class="pagenum"><a name="Page_138" id="Page_138">[Pg 138]</a></span>
+almost its entire length was marked by bloody bruises. The
+papillæ on these places were destroyed, although the walls were
+not entirely perforated. In the appendix were found two or three
+dead larvæ. Alessandri (1910) has likewise shown that the larvæ
+cause intestinal lesions.</p>
+
+<p>According to Graham-Smith, Austen (1912) has recorded a case
+of myasis of the nose, attended with a profuse watery discharge of
+several weeks duration and pain, due to the larvæ of <i>Piophila casei</i>.</p>
+
+
+<p><a name="Anthyomyiidae" id="Anthyomyiidae"></a><b>Anthyomyiidæ</b>&mdash;The characteristic larvæ of two species of <i>Fannia</i>
+(= <i>Homalomyia</i> or <i>Anthomyia</i>, in part) (<a href="#Fig_101">fig.&nbsp;101</a>) are the most commonly
+reported of dipterous
+larvæ causing intestinal
+myasis. Hewitt
+(1912) has presented a
+valuable study of the bionomics
+and of the larvæ
+of these flies, a type of
+what is needed for all the
+species concerned in myasis.
+We have seen two
+cases of their having been
+passed in stools, without having caused any special symptoms.
+In other instances their presence in the alimentary canal has given
+rise to symptoms vaguely described as those of tapeworm infestation,
+or helminthiasis. More specifically, they have been described as
+causing vertigo, severe headache, nausea and vomiting, severe
+abdominal pains, and in some instances, bloody diarrh&oelig;a.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_100" id="Fig_100"></a>
+<a href="images/f100-full.png"><img src="images/f100.png" width="500" height="306" alt="100. Fannia canicularis (×4). After Graham-Smith." title="100. Fannia canicularis (×4). After Graham-Smith." /></a>
+<span class="caption">100. Fannia canicularis (×4). After Graham-Smith.</span>
+</div>
+
+<p>One of the most striking cases is that reported by Blankmeyer
+(1914), of a woman whose illness began fourteen years previously
+with nausea and vomiting. After several months of illness she began
+passing larvæ and was compelled to resort to enemas. Three years
+previous to the report, she noticed frequent shooting pains in the
+rectal region and at times abdominal tenderness was marked. There
+was much mucus in the stools and she "experienced the sensation
+of larvæ crawling in the intestine." Occipital headaches were
+marked, with remissions, and constipation became chronic. The
+appetite was variable, there was a bad taste in the mouth, tongue
+furred and ridged, and red at the edges. Her complexion was sallow,
+and general nervousness was marked. As treatment, there
+were given doses of magnesium sulphate before breakfast and at<span class="pagenum"><a name="Page_139" id="Page_139">[Pg 139]</a></span>
+4 <span class="smcap">P. M.</span>, with five grain doses of salol four times a day. The customary
+parasiticides yielded no marked benefit. At the time of the report
+the patient passed from four to fifty larvæ per day, and was showing
+some signs of improvement. The nausea had disappeared, her
+nervousness was less evident, and there was a slight gain in weight.</p>
+
+<div class="figleft" style="width: 200px;"><a name="Fig_101" id="Fig_101"></a>
+<a href="images/f101-full.png"><img src="images/f101.png" width="200" height="442" alt="101. Larva of Fannia
+scalaris." title="101. Larva of Fannia
+scalaris." /></a>
+<span class="caption">101. Larva of Fannia
+scalaris.</span>
+</div>
+
+<p>The case was complicated by various other disorders, but the
+symptoms given above seem to be in large part attributable to the
+myasis. There is nothing in the case to justify the assumption
+that larvæ were continuously present, for years. It seems more
+reasonable to suppose that something in the habits of the patient
+favored repeated infestation. Nevertheless, a study of the various
+cases of intestinal myasis caused by these and
+other species of dipterous larvæ seems to indicate
+that the normal life cycle may be considerably
+prolonged under the unusual conditions.</p>
+
+<p>The best authenticated cases of myasis of the
+urinary passage have been due to larvæ of
+<i>Fannia</i>. Chevril (1909) collected and described
+twenty cases, of which seven seemed beyond
+doubt. One of these was that of a woman of
+fifty-five who suffered from albuminuria, and
+urinated with much difficulty, and finally passed
+thirty to forty larvæ of <i>Fannia canicularis</i>.</p>
+
+<p>It is probable that infestation usually occurs
+through eating partially decayed fruit or vegetables
+on which the flies have deposited their
+eggs. Wellman points out that the flies may
+deposit their eggs in or about the anus of
+persons using outside privies and Hewitt
+believes that this latter method of infection is probably the common
+one in the case of infants belonging to careless mothers. "Such
+infants are sometimes left about in an exposed and not very clean
+condition, in consequence of which flies are readily attracted to them
+and deposit their eggs."</p>
+
+
+<p><a name="Muscinae" id="Muscinae"></a><b>Muscinæ</b>&mdash;The larvæ of the common house-fly, <i>Musca domestica</i>,
+are occasionally recorded as having been passed with the feces or
+vomit of man. While such cases may occur, it is probable that in
+most instances similar appearing larvæ of other insects have been
+mistakenly identified.<span class="pagenum"><a name="Page_140" id="Page_140">[Pg 140]</a></span></p>
+
+<p><i>Muscina stabulans</i> is regarded
+by Portschinsky
+(1913) as responsible for
+many of the cases of intestinal
+myasis attributed to other
+species. He records the case
+of a peasant who suffered from
+pains in the lower part of the
+breast and intestines, and
+whose stools were mixed with
+blood. From November until
+March he had felt particularly
+ill, being troubled with
+nausea and vomiting in addition
+to the pain in his intestines. In March, his physician prescribed
+injections of a concentrated solution of tannin, which resulted in the
+expulsion of fifty living larvæ of <i>Muscina stabulans</i>. Thereafter
+the patient felt much better, although he suffered from intestinal
+catarrh in a less severe form.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_102" id="Fig_102"></a>
+<a href="images/f102-full.png"><img src="images/f102.png" width="450" height="386" alt="102. Muscina stabulans (×4). After Graham-Smith." title="102. Muscina stabulans (×4). After Graham-Smith." /></a>
+<span class="caption">102. Muscina stabulans (×4). After Graham-Smith.</span>
+</div>
+
+
+<p><a name="Calliphorinae" id="Calliphorinae"></a><b>Calliphorinæ</b>&mdash;Closely related to the Sarcophagidæ are the
+<i>Calliphorinæ</i>, to which group belong many of the so-called "blue
+bottle" flies. Their larvæ feed upon dead animals, and upon fresh
+and cooked meat. Those of <i>Protocalliphora</i>,
+already mentioned,
+are ectoparasitic on living nestling
+birds. Larva of <i>Lucilia</i>, we have
+taken from tumors on living turtles.
+To this sub-family belongs also
+<i>Auchmeromyia luteola</i>, the Congo
+floor maggot. Some of these,
+and at least the last mentioned,
+are confirmed, rather than faculative
+parasites. Various species of
+Calliphorinæ are occasionally met
+with as facultative parasites of
+man.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_103" id="Fig_103"></a>
+<a href="images/f103-full.png"><img src="images/f103.png" width="400" height="407" alt="103. Lucilia cæsar, (×3). After Howard." title="103. Lucilia cæsar, (×3). After Howard." /></a>
+<span class="caption">103. Lucilia cæsar, (×3). After Howard.</span>
+</div>
+
+<p><i>Chrysomyia macellaria</i>, the screw worm fly (<a href="#Fig_107">fig.&nbsp;107</a>), is the fly
+which is responsible for the most serious cases of human myasis in
+the United States. It is widely distributed in the United States<span class="pagenum"><a name="Page_141" id="Page_141">[Pg 141]</a></span>
+but is especially abundant in the south. While the larvæ breed in
+decaying matter in general, they so commonly breed in the living
+flesh of animals that they merit rank as true parasites. The females
+are attracted to open wounds of all kinds on cattle and other animals
+and quickly deposit large numbers of eggs. Animals which have
+been recently castrated, dehorned, or branded, injured by barbed
+wire, or even by the attacks of ticks are promptly attacked in the
+regions where the fly abounds. Even the navel of young calves or
+discharges from the vulva of cows may attract the insect.</p>
+
+<div class="figcenter" style="width: 500px;">
+<a href="images/f104-full.png"><img src="images/f104.png" width="500" height="300" alt="104. Calliphora erythrocephala, (×6). After Graham-Smith." title="104. Calliphora erythrocephala, (×6). After Graham-Smith." /></a>
+<span class="caption">104. Calliphora erythrocephala, (×6). After Graham-Smith.</span>
+</div>
+
+<p>Not infrequently the fly attacks man, being attracted by an offensive
+breath, a chronic catarrh, or a purulent discharge from the
+ears. Most common are the cases where the eggs are deposited in
+the nostrils. The larvæ, which are hatched in a day or two, are
+provided with strong spines and proceed to bore into the tissues
+of the nose, even down into or through the bone, into the frontal
+sinus, the pharynx, larynx, and neighboring parts.</p>
+
+<p>Osborn (1896) quotes a number of detailed accounts of the attacks
+of the <i>Chrysomyia</i> on man. A vivid picture of the symptomology
+of rhinal myasis caused by the larvæ of this fly is given by Castellani
+and Chalmers: "Some couple of days after a person suffering from
+a chronic catarrh, foul breath, or ozæna, has slept in the open or has
+been attacked by a fly when riding or driving,&mdash;<i>i.e.</i>, when the hands
+are engaged&mdash;signs of severe catarrh appear, accompanied with
+inordinate sneezing and severe pain over the root of the nose or the
+frontal bone. Quickly the nose becomes swollen, and later the face
+also may swell, while examination of the nose may show the presence<span class="pagenum"><a name="Page_142" id="Page_142">[Pg 142]</a></span>
+of the larvæ. Left untreated, the patient rapidly becomes worse,
+and pus and blood are discharged from the nose, from which an
+offensive odor issues. Cough appears as well as fever, and often
+some delirium. If the patient lives long enough, the septum of the
+nose may fall in, the soft and hard palates may be pierced, the wall
+of the pharynx may be destroyed. By this time, however, the course
+of the disease will have become quite evident by the larvæ dropping
+out of the nose, and if the patient continues to live all the larvæ
+may come away naturally."</p>
+
+<p>For treatment of rhinal myasis these writers recommend douching
+the nose with chloroform water or a solution of chloroform in
+sweet milk (10-20 per cent), followed by douches of mild antiseptics.
+Surgical treatment may be necessary.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_105" id="Fig_105"></a>
+<a href="images/f105-full.png"><img src="images/f105.png" width="500" height="296" alt="105. Larva of a flesh fly (Sarcophaga). Caudal aspect. Anterior stigmata. Pharyngeal skeleton." title="105. Larva of a flesh fly (Sarcophaga). Caudal aspect. Anterior stigmata. Pharyngeal skeleton." /></a>
+<span class="caption">105. Larva of a flesh fly (Sarcophaga). Caudal aspect. Anterior stigmata. Pharyngeal skeleton.</span>
+</div>
+
+
+<p><a name="Sarcophagidae" id="Sarcophagidae"></a><b>Sarcophagidæ</b>&mdash;The larvæ (<a href="#Fig_105">fig.&nbsp;105</a>) of flies of this family usually
+feed upon meats, but have been found in cheese, oleomargerine,
+pickled herring, dead and living insects, cow dung and human feces.
+Certain species are parasitic in insects. Higgins (1890) reported
+an instance of "hundreds" of larvæ of <i>Sarcophaga</i> being vomited by a
+child eighteen months of age. There was no doubt as to their origin
+for they were voided while the physician was in the room. There
+are many other reports of their occurrence in the alimentary canal.
+We have recorded elsewhere (Riley, 1906) a case in which some ten
+or twelve larvæ of <i>Sarcophaga</i> were found feeding on the diseased
+tissues of a malignant tumor. The tumor, a melanotic sarcoma,
+was about the size of a small walnut, and located in the small of the
+back of an elderly lady. Although they had irritated and caused a
+slight hæmorrhage, neither the patient nor others of the family knew<span class="pagenum"><a name="Page_143" id="Page_143">[Pg 143]</a></span>
+of their presence. Any discomfort which they had caused had been
+attributed to the sarcomatous growth. The infestation occurred
+in mid-summer. It is probable that the adult was attracted by the
+odor of the discharges and deposited the living maggots upon the
+diseased tissues.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_106" id="Fig_106"></a>
+<a href="images/f106-full.png"><img src="images/f106.png" width="500" height="347" alt="106. A flesh fly (Sarcophaga), (×4). After Graham-Smith." title="106. A flesh fly (Sarcophaga), (×4). After Graham-Smith." /></a>
+<span class="caption">106. A flesh fly (Sarcophaga), (×4). After Graham-Smith.</span>
+</div>
+
+<p>According to Küchenmeister, <i>Sarcophaga carnaria</i> (<a href="#Fig_106">fig.&nbsp;106</a>),
+attracted by the odor, deposits its eggs and larvæ in the vagina of
+girls and women when they lie naked in hot summer days upon dirty
+clothes, or when they have a discharge from the vagina. In malignant
+inflammations of the eyes the larvæ
+even nestle under the eyelids and in
+Egypt, for example, produce a very
+serious addition to the effects of small-pox
+upon the cornea, as according to
+Pruner, in such cases perforation of the
+cornea usually takes place.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_107" id="Fig_107"></a>
+<a href="images/f107-full.png"><img src="images/f107.png" width="350" height="475" alt="107. Chrysomyia macellaria, (×3)." title="107. Chrysomyia macellaria, (×3)." /></a>
+<span class="caption">107. Chrysomyia macellaria, (×3).</span>
+</div>
+
+<p><i>Wohlfartia magnifica</i> is another
+Sarcophagid which commonly infests
+man in the regions where it is abundant.
+It is found in all Europe but is
+especially common in Russia, where
+Portschinsky has devoted much attention
+to its ravages. It deposits living
+larvæ in wounds, the nasal fossæ, the
+ears and the eyes, causing injuries
+even more revolting than those described for <i>Chrysomyia</i>.<span class="pagenum"><a name="Page_144" id="Page_144">[Pg 144]</a></span></p>
+
+
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="CHAPTER_V" id="CHAPTER_V"></a>CHAPTER V</h2>
+
+<h2>ARTHROPODS AS SIMPLE CARRIERS OF DISEASE</h2>
+
+
+<p>The fact that certain arthropods are poisonous, or may affect the
+health of man as direct parasites has always received attention in
+the medical literature. We come now to the more modern aspect
+of our subject,&mdash;the consideration of insects and other arthropods
+as transmitters and disseminators of disease.</p>
+
+<p>The simplest way in which arthropods may function in this
+capacity is as <i>simple carriers</i> of pathogenic organisms. It is conceivable
+that any insect which has access to, and comes in contact
+with such organisms and then passes to the food, or drink, or to the
+body of man, may in a wholly accidental and incidental manner
+convey infection. That this occurs is abundantly proved by the
+work of recent years. We shall consider as typical the case against
+the house-fly, which has attracted so much attention, both popular
+and scientific. The excellent general treatises of Hewitt (1910),
+Howard (1911), and Graham-Smith (1913), and the flood of bulletins
+and popular literature render it unnecessary to consider the topic
+in any great detail.</p>
+
+
+<h3><a name="The_House-fly_As_a_Carrier_of_Disease" id="The_House-fly_As_a_Carrier_of_Disease"></a><span class="smcap">The House-fly As a Carrier of Disease</span></h3>
+
+<p>Up to the past decade the house-fly has usually been regarded as a
+mere pest. Repeatedly, however, it had been suggested that it
+might disseminate disease. We have seen that as far back as the
+sixteenth century, Mercurialis suggested that it was the agent in the
+spread of bubonic plague, and in 1658, Kircher reiterated this view.
+In 1871, Leidy expressed the opinion that flies were probably a means
+of communicating contagious diseases to a greater degree than was
+generally suspected. From what he had observed regarding gangrene
+in hospitals, he thought flies should be carefully excluded from
+wounds. In the same year, the editor of the <i>London Lancet</i>, referring
+to the belief that they play a useful rôle in purifying the air said,
+"Far from looking upon them as dipterous angels dancing attendance
+on Hygeia, regard them rather in the light of winged sponges spreading
+hither and thither to carry out the foul behests of Contagion."</p>
+
+<p>These suggestions attracted little attention from medical men, for
+it is only within very recent years that the charges have been supported
+by direct evidence. Before considering this evidence, it is<span class="pagenum"><a name="Page_145" id="Page_145">[Pg 145]</a></span>
+necessary that we define what is meant by "house-fly" and that we
+then consider the life-history of the insect.</p>
+
+<p>There are many flies which are occasionally to be found in houses,
+but according to various counts, from 95 per cent to 99 per cent of
+these in warm weather in the Eastern United States belong to the
+one species <i>Musca domestica</i> (<a href="#Fig_108">fig.&nbsp;108</a>). This is the dominant house-fly
+the world over and is the one which merits the name. It has been
+well characterized by Schiner (1864), whose description has been
+freely translated by Hewitt, as follows:</p>
+
+<p>"Frons of male occupying a fourth part of the breadth of the head.
+Frontal stripe of female narrow in front, so broad behind that it
+entirely fills up the width of the frons. The dorsal region of the
+thorax dusty grey in color with four equally broad longitudinal
+stripes. Scutellum gray with black sides. The light regions of
+the abdomen yellowish, transparent, the darkest parts at least at
+the base of the ventral side yellow. The last segment and a dorsal
+line blackish brown. Seen from behind and against the light, the
+whole abdomen shimmering yellow, and only on each side of the
+dorsal line on each segment a dull transverse band. The lower part
+of the face silky yellow, shot with blackish brown. Median stripe
+velvety black. Antennæ brown. Palpi black. Legs blackish
+brown. Wings tinged with pale gray with yellowish base. The
+female has a broad velvety back, often reddishly shimmering frontal
+stripe, which is not broader at the anterior end than at the bases of
+the antennæ, but become so very much broader above that the light
+dustiness of the sides is entirely obliterated. The abdomen gradually
+becoming darker. The shimmering areas on the separate segments
+generally brownish. All the other parts are the same as in
+the male."</p>
+
+<p>The other species of flies found in houses in the Eastern United
+States which are frequently mistaken for the house or typhoid fly
+may readily be distinguished by the characters of the following key:</p>
+
+<div class="blockquot"><div class="hanging">
+<p><i>a.</i> Apical cell (<span title="for Rs read R_5"><a name="AC_9" id="AC_9"></a>R<sub>s</sub></span>) of the wide wing open, i.e., the bounding veins
+parallel or divergent (<a href="#Fig_100">fig.&nbsp;100</a>). Their larvæ are flattened, the
+intermediate body segments each fringed with fleshy, more or
+less spinose, processes. <span class="rightalign"><i>Fannia</i></span></p>
+
+<div class="hanging">
+<p>b. Male with the sides of the second and third abdominal segments
+translucent yellowish. The larva with three pairs
+of nearly equal spiniferous appendages on each segment,<span class="pagenum"><a name="Page_146" id="Page_146">[Pg 146]</a></span>
+arranged in a longitudinal series and in addition two pairs
+of series of smaller processes (<a href="#Fig_100">fig.&nbsp;100</a>) <span class="rightalign"><i>F. canicularis</i></span></p>
+
+<p>bb. Male with blackish abdomen, middle tibia with a tubercle
+beyond the middle. The larva with spiniferous appendages
+of which the dorsal and ventral series are short, the
+lateral series long and feathered (<a href="#Fig_101">fig.&nbsp;101</a>) <span class="rightalign"><i>F. scalaris</i></span></p>
+</div>
+
+<p>aa. Apical cell (R) of the wing more or less narrowed in the
+margin; i.&nbsp;e., the bounding veins more or less converging
+(<a href="#Fig_108">fig.&nbsp;108</a>).</p>
+
+<div class="hanging">
+<p>b. The mouth-parts produced and pointed, fitted for piercing.</p>
+
+<div class="hanging">
+<p>c. Palpi much shorter than the proboscis; a brownish gray
+fly, its thorax with three rather broad whitish stripes;
+on each border of the middle stripe and on the mesal
+borders of the lateral stripes is a blackish brown line.
+Abdomen yellowish brown; on the second, third and
+fourth segments are three brown spots which may be
+faint or even absent. The larvæ live in dung. The
+stable-fly (<a href="#Fig_110">fig.&nbsp;110</a>) <span class="rightalign"><i>Stomoxys calcitrans</i></span></p>
+
+<p>cc. Palpi nearly as long as the proboscis. Smaller species
+than the house-fly. The horn-fly (<a href="#Fig_167">fig.&nbsp;167</a>)
+<span class="rightalign"><i>Hæmatobia irritans</i></span></p>
+</div>
+
+<p>bb. Mouth-parts blunt, fitted for lapping.</p>
+
+<div class="hanging">
+<p>c. Thorax, particularly on the sides and near the base of the
+wings with soft golden yellow hairs among the bristles.
+This fly is often found in the house in very early spring
+or even in the winter. The cluster-fly, <span class="rightalign"><i>Pollenia rudis</i></span></p>
+
+<p>cc. Thorax without golden yellow hairs among the bristles.</p>
+
+<div class="hanging">
+<p>d. The last segment of the vein M with an abrupt
+angle. (<a href="#Fig_108">fig.&nbsp;108</a>). The larvæ live in manure,
+etc. <span class="rightalign">House-fly, <i>Musca domestica</i></span></p>
+
+<p>dd. The last segment of vein M with a broad, gentle
+curve (<a href="#Fig_102">fig.&nbsp;102</a>).</p>
+
+<div class="hanging">
+<p>e. Eyes microscopically hairy; each abdominal
+segment with two spots. Larvæ in dung.
+<span class="rightalign"><i>Myiospila meditabunda</i></span></p>
+
+<p>ee. Eyes bare; abdomen gray and brown marbled.
+<span class="rightalign"><i>Muscina</i></span></p>
+
+<div class="hanging">
+<p>f. With black legs and palpi. <span class="rightalign"><i>M. assimilis</i></span><span class="pagenum"><a name="Page_147" id="Page_147">[Pg 147]</a></span></p>
+
+<p>ff. With legs more or less yellowish; palpi
+yellow. Larvæ in decaying vegetable
+substances, dung, etc. <span class="rightalign"><i>M. stabulans</i></span></p>
+</div></div></div></div></div></div></div>
+
+<p>It is almost universally believed that the adults of <i>Musca domestica</i>
+hibernate, remaining dormant throughout the winter in attics,
+around chimneys, and in sheltered but cold situations. This belief
+has been challenged by Skinner (1913), who maintains that all the
+adult flies die off during the fall and early winter and that the species
+is carried over in the pupal stage, and in no other way. The cluster-fly,
+<i>Pollenia rudis</i>, undoubtedly does hibernate in attics and similar
+situations and is often mistaken for the house-fly. In so far as
+concerns <i>Musca domestica</i>, the important question as to hibernation
+in the adult stage is an open one. Many observations by one of the
+writers (Johannsen) tend to confirm Dr. Skinner's conclusion, in so
+far as it applies to conditions in the latitude of New York State.
+Opposed, is the fact that various experimenters, notably Hewitt
+(1910) and Jepson (1909) wholly failed to carry pupæ through the
+winter.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_108" id="Fig_108"></a>
+<a href="images/f108-full.png"><img src="images/f108.png" width="500" height="259" alt="108. The house or typhoid fly (Musca domestica (×4)). After Howard." title="108. The house or typhoid fly (Musca domestica (4×)). After Howard." /></a>
+<span class="caption">108. The house or typhoid fly (Musca domestica (4×)). After Howard.</span>
+</div>
+
+<p>The house-fly breeds by preference in horse manure. Indeed,
+Dr. Howard, whose extensive studies of the species especially qualify
+him for expressing an opinion on the subject, has estimated that under
+ordinary city and town conditions, more than ninety per cent of the
+flies present in houses have come from horse stables or their vicinity.
+They are not limited to such localities, by any means, for it has been
+found that they would develop in almost any fermenting organic
+substance. Thus, they have been bred from pig, chicken, and cow<span class="pagenum"><a name="Page_148" id="Page_148">[Pg 148]</a></span>
+manure, dirty waste paper, decaying vegetation, decaying meat,
+slaughter-house refuse, sawdust-sweepings, and many other sources.
+A fact which makes them especially dangerous as disease-carriers
+is that they breed readily in human excrement.</p>
+
+<p>The eggs are pure white, elongate ovoid, somewhat broader at
+the anterior end. They measure about one millimeter (1-25 inch)
+in length. They are deposited in small, irregular clusters, one
+hundred and twenty to one hundred and fifty from a single fly. A
+female may deposit as many as four batches in her life time. The
+eggs hatch in from eight to twenty-four hours.</p>
+
+<p>The newly hatched larva, or maggot (<a href="#Fig_108">fig.&nbsp;108</a>), measures about two
+millimeters (1-12 inch) in length. It is pointed at the head end and
+blunt at the opposite end, where the spiracular openings are borne.
+It grows rapidly, molts three times and reaches maturity in from six
+to seven days, under favorable conditions.</p>
+
+<p>The pupal stage, like that of related flies, is passed in the old
+larval skin which, instead of being molted, becomes contracted and
+heavily chitinized, forming the so-called <i>puparium</i> (<a href="#Fig_108">fig.&nbsp;108</a>). The
+pupal stage may be completed in from three to six days.</p>
+
+<p>Thus during the warm summer months a generation of flies may
+be produced in ten to twelve days. Hewitt at Manchester, England,
+found the minimum to be eight days but states that larvæ bred in
+the open air in horse manure which had an average daily temperature
+of 22.5° C., occupied fourteen to twenty days in their development,
+according to the air temperature.</p>
+
+<p>After emergence, a period of time must elapse before the fly is
+capable of depositing eggs. This period has been tuned the <i>preoviposition</i>
+period. Unfortunately we have few exact data regarding
+this period. Hewitt found that the flies became sexually mature in
+ten to fourteen days after their emergence from the pupal state and
+four days after copulation they began to deposit their eggs; in other
+words the preoviposition stage was fourteen days or longer. Griffith
+(1908) found this period to be ten days. Dr. Howard believes that
+the time "must surely be shorter, and perhaps much shorter, under
+midsummer conditions, and in the freedom of the open air." He
+emphasizes that the point is of great practical importance, since it is
+during this period that the trapping and other methods of destroying
+the adult flies, will prove most useful.</p>
+
+<p>Howard estimates that there may be nine generations of flies a
+year under outdoor conditions in places comparable in climate to<span class="pagenum"><a name="Page_149" id="Page_149">[Pg 149]</a></span>
+Washington. The number may be considerably increased in warmer
+climates.</p>
+
+<p>The rate at which flies may increase under favorable conditions is
+astounding. Various writers have given estimates of the numbers of
+flies which may develop as the progeny of a single individual, providing
+all the eggs and all the individual flies survived. Thus, Howard
+estimates that from a single female, depositing one hundred and
+twenty eggs on April 15th, there may be by September 10th,
+5,598,720,000,000 adults. Fortunately, living forms do not produce
+in any such mathematical manner and the chief value of the figures
+is to illustrate the enormous struggle for existence which is constantly
+taking place in nature.</p>
+
+<p>Flies may travel for a considerable distance to reach food and
+shelter, though normally they pass to dwellings and other sources
+of food supply in the immediate neighborhood of their breeding
+places. Copeman, Howlett and Merriman (1911) marked flies by
+shaking them in a bag containing colored chalk. Such flies were
+repeatedly recovered at distances of eight to one thousand yards
+and even at a distance of seventeen hundred yards, nearly a mile.</p>
+
+<p>Hindle and Merriman (1914) continued these experiments on a
+large scale at Cambridge, England. They "do not think it likely
+that, as a rule, flies travel more than a quarter of a mile in thickly-housed
+areas." In one case a single fly was recovered at a distance
+of 770 yards but a part of this distance was across open fen-land.
+The surprising fact was brought out that flies tend to travel either
+<i>against</i> or across the wind. The actual direction followed may be
+determined either directly by the action of the wind (positive anemotropism),
+or indirectly owing to the flies being attracted by any odor
+that it may convey from a source of food. They conclude that it is
+likely that the chief conditions favoring the disposal of flies are fine
+weather and a warm temperature. The nature of the locality is
+another considerable factor. Hodge (1913) has shown that when
+aided by the wind they may fly to much greater distances over the
+water. He reports that at Cleveland, Ohio, the cribs of the water
+works, situated a mile and a quarter, five miles, and six miles out in
+Lake Erie are invaded by a regular plague of flies when the wind
+blows from the city. Investigation showed that there was absolutely
+nothing of any kind in which flies could breed on the crib.</p>
+
+<p>The omnivorous habits of the house-fly are matters of everyday
+observation. From our view point, it is sufficient to emphasize<span class="pagenum"><a name="Page_150" id="Page_150">[Pg 150]</a></span>
+that from feeding on excrement, on sputum, on open sores, or on
+putrifying matter, the flies may pass to the food or milk upon the table
+or to healthy mucous membranes, or uncontaminated wounds.
+There is nothing in its appearance to tell whether the fly that comes
+blithely to sup with you is merely unclean, or whether it has just
+finished feeding upon dejecta teeming with typhoid bacilli.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_109" id="Fig_109"></a>
+<a href="images/f109-full.png"><img src="images/f109.png" width="350" height="350" alt="109. Pulvillus of foot of house-fly, showing glandular hairs." title="109. Pulvillus of foot of house-fly, showing glandular hairs." /></a>
+<span class="caption">109. Pulvillus of foot of house-fly, showing glandular hairs.</span>
+</div>
+
+<p>The method of feeding of the house-fly has an important bearing
+on the question of its ability to transmit pathogenic organisms.
+Graham-Smith (1910) has shown that when feeding, flies frequently
+moisten soluble substances with "vomit" which is regurgitated from
+the crop. This is, of course, loaded with bacteria from previous
+food. When not sucked up again these drops of liquid dry, and produce
+round marks with an opaque center and rim and an intervening
+less opaque area. Fly-specks, then, consist of both vomit spots
+and feces. Graham-Smith shows a photograph of a cupboard window
+where, on an area six inches square, there were counted eleven hundred
+and two vomit marks and nine fecal deposits.<span class="pagenum"><a name="Page_151" id="Page_151">[Pg 151]</a></span></p>
+
+<p>From a bacteriologist's viewpoint a discussion of the possibility
+of a fly's carrying bacteria would seem superfluous. Any exposed
+object, animate or inanimate, is contaminated by bacteria and will
+transfer them if brought into contact with suitable culture media,
+whether such substance be food, or drink, open wounds, or the sterile
+culture media of the laboratory. A needle point may convey enough
+germs to produce disease. Much more readily may the house-fly
+with its covering of hairs and its sponge-like pulvilli (<a href="#Fig_109">fig.&nbsp;109</a>) pick
+up and transfer bits of filth and other contaminated material.</p>
+
+<p>For popular instruction this inevitable transfer of germs by the
+house-fly is strikingly demonstrated by the oft copied illustration
+of the tracks of a fly on a sterile culture plate. Two plates of gelatine
+or, better, agar medium are prepared. Over one of these a fly
+(with wings clipped) is allowed to walk, the other is kept as a check.
+Both are put aside at room temperature, to be examined after twenty-four
+to forty-eight hours. At the end of that time, the check plate
+is as clear as ever, the one which the fly has walked is dotted with
+colonies of bacteria and fungi. The value in the experiment consists
+in emphasizing that by this method we merely render visible what is
+constantly occurring in nature.</p>
+
+<p>A comparable experiment which we use in our elementary laboratory
+work is to take three samples of <i>clean</i> (preferably, sterile) fresh
+milk in sterile bottles. One of them is plugged with a pledget of
+cotton, into the second is dropped a fly from the laboratory and into
+the third is dropped a fly which has been caught feeding upon garbage
+or other filth. After a minute or two the flies are removed and
+the vials plugged as was number one. The three are then set aside
+at room temperature. When examined after twenty-four hours
+the milk in the first vial is either still sweet or has a "clean" sour odor;
+that of the remaining two is very different, for it has a putrid odor,
+which is usually more pronounced in the case of sample number
+three.</p>
+
+<p>Several workers have carried out experiments to determine the
+number of bacteria carried by flies under natural conditions. One
+of the most extended and best known of these is the series by Esten
+and Mason (1908). These workers caught flies from various sources
+in a sterilized net, placed them in a sterile bottle and poured over
+them a known quantity of sterilized water, in which they were shaken
+so as to wash the bacteria from their bodies. They found the number
+of bacteria on a single fly to range from 550 to 6,600,000. Early in<span class="pagenum"><a name="Page_152" id="Page_152">[Pg 152]</a></span>
+the fly season the numbers of bacteria on flies are comparatively
+small, while later the numbers are comparatively very large. The
+place where flies live also determines largely the numbers that they
+carry. The lowest number, 550, was from a fly caught in the
+bacteriological laboratory, the highest number, 6,600,000 was the
+average from eighteen swill-barrel flies. Torrey (1912) made examination
+of "wild" flies from a tenement house district of New York
+City. He found "that the surface contamination of these 'wild'
+flies may vary from 570 to 4,400,000 bacteria per insect, and the
+intestinal bacterial content from 16,000 to 28,000,000."</p>
+
+<p>Less well known in this country is the work of Cox, Lewis, and
+Glynn (1912). They examined over four hundred and fifty naturally
+infected house-flies in Liverpool during September and early October.
+Instead of washing the flies they were allowed to swim on the surface
+of sterile water for five, fifteen, or thirty minutes, thus giving natural
+conditions, where infection occurs from vomit and dejecta of the
+flies, as well as from their bodies. They found, as might be expected,
+that flies from either insanitary or congested areas of the city contain
+far more bacteria than those from the more sanitary, less congested,
+or suburban areas. The number of aerobic bacteria from the former
+varied from 800,000 to 500,000,000 per fly and from the latter from
+21,000 to 100,000. The number of intestinal forms conveyed by
+flies from insanitary or congested areas was from 10,000 to 333,000,000
+as compared with from 100 to 10,000 carried by flies from the more
+sanitary areas.</p>
+
+<p>Pathogenic bacteria and those allied to the food poisoning group
+were only obtained from the congested or moderately congested
+areas and not from the suburban areas, where the chances of infestation
+were less.</p>
+
+<p>The interesting fact was brought out that flies caught in milk
+shops apparently carry and obtain more bacteria than those from
+other shops with exposed food in a similar neighborhood. The
+writers explained this as probably due to the fact that milk when
+accessible, especially during the summer months, is suitable culture
+medium for bacteria, and the flies first inoculate the milk and later
+reinoculate themselves, and then more of the milk, so establishing a
+vicious circle.</p>
+
+<p>They conclude that in cities where food is plentiful flies rarely
+migrate from the locality in which they are bred, and consequently
+the number of bacteria which they carry depends upon the general<span class="pagenum"><a name="Page_153" id="Page_153">[Pg 153]</a></span>
+standard of cleanliness in that locality. Flies caught in a street of
+modern, fairly high class, workmen's dwellings forming a sanitary
+oasis in the midst of a slum area, carried far less bacteria than those
+caught in the adjacent neighborhood.</p>
+
+<p>Thus, as the amount of dirt carried by flies in any particular
+locality, measured in the terms of bacteria, bears a definite relation
+to the habits of the people and to the state of the streets, it demonstrates
+the necessity of efficient municipal and domestic cleanliness,
+if the food of the inhabitants is to escape pollution, not only with
+harmless but also with occasional pathogenic bacteria.</p>
+
+<p>The above cited work is of a general nature, but, especially in
+recent years, many attempts have been made to determine more
+specifically the ability of flies to transmit pathogenic organisms.
+The critical reviews of Nuttall and Jepson (1909), Howard (1911),
+and Graham-Smith (1913) should be consulted by the student of
+the subject. We can only cite here a few of the more striking experiments.</p>
+
+<p>Celli (1888) fed flies on pure cultures of <i>Bacillus typhosus</i> and declared
+that he was able to recover these organisms from the intestinal
+contents and excrement.</p>
+
+<p>Firth and Horrocks (1902), cited by Nuttall and Jepson, "kept
+<i>Musca domestica</i> (also bluebottles) in a large box measuring 4 × 3 × 3
+feet, with one side made of glass. They were fed on material
+contaminated with cultures of <i>B. typhosus</i>. Agar plates, litmus,
+glucose broth and a sheet of clean paper were at the same time
+exposed in the box. After a few days the plates and broth were
+removed and incubated with a positive result." Graham-Smith
+(1910) "carried out experiments with large numbers of flies kept
+in gauze cages and fed for eight hours on emulsions of <i>B. typhosus</i>
+in syrup. After that time the infested syrup was removed and the
+flies were fed on plain syrup. <i>B. typhosus</i> was isolated up to 48
+hours (but not later) from emulsions of their feces and from plates
+over which they walked."</p>
+
+<p>Several other workers, notably Hamilton (1903), Ficker (1903),
+Bertarelli (1910) Faichnie (1909), and Cochrane (1912), have isolated
+<i>B. typhosus</i> from "wild" flies, naturally infected. The papers
+of Faichnie and of Cochrane we have not seen, but they are quoted
+in <i>extenso</i> by Graham-Smith (1913).</p>
+
+<p>On the whole, the evidence is conclusive that typhoid germs not
+only may be accidentally carried on the bodies of house-flies but<span class="pagenum"><a name="Page_154" id="Page_154">[Pg 154]</a></span>
+may pass through their bodies and be scattered in a viable condition
+in the feces of the fly for at least two days after feeding. Similar,
+results have been reached in experiments with cholera, tuberculosis
+and yaws, the last-mentioned being a spirochæte disease. Darling
+(1913) has shown that murrina, a trypanosome disease of horses
+and mules in the Canal zone is transmitted by house-flies which feed
+upon excoriated patches of diseased animals and then pass to cuts
+and galls of healthy animals.</p>
+
+<p>Since it is clear that flies are abundantly able to disseminate
+viable pathogenic bacteria, it is important to consider whether they
+have access to such organisms in nature. A consideration of the
+method of spread of typhoid will serve to illustrate the way in which
+flies may play an important rôle.</p>
+
+<p>Typhoid fever is a specific disease caused by <i>Bacillus typhosus</i>,
+and by it alone. The causative organism is to be found in the excrement
+and urine of patients suffering from the disease. More than
+that, it is often present in the dejecta for days, weeks, or even months
+and years, after the individual has recovered from the disease.
+Individuals so infested are known as "typhoid carriers" and they,
+together with those suffering from mild cases, or "walking typhoid,"
+are a constant menace to the health of the community in which they
+are found.</p>
+
+<p>Human excrement is greedily visited by flies, both for feeding and
+for ovipositing. The discharges of typhoid patients, or of chronic
+"carriers," when passed in the open, in box privies, or camp latrines,
+or the like, serve to contaminate myriads of the insects which may
+then spread the germ to human food and drink. Other intestinal
+diseases may be similarly spread. There is abundant epidæmiological
+evidence that infantile diarrh&oelig;a, dysentery, and cholera may be
+so spread.</p>
+
+<p>Stiles and Keister (1913) have shown that spores of <i>Lamblia
+intestinalis</i>, a flagellate protozoan living in the human intestine,
+may be carried by house-flies. Though this species is not normally
+pathogenic, one or more species of <i>Entam&oelig;ba</i> are the cause of a type
+of a highly fatal tropical dysentery. Concerning it, and another
+protozoan parasite of man, they say, "If flies can carry <i>Lamblia</i>
+spores measuring 10 to 7µ, and bacteria that are much smaller, and
+particles of lime that are much larger, there is no ground to assume
+that flies may not carry <i>Entam&oelig;ba</i> and <i>Trichomonas</i> spores."<span class="pagenum"><a name="Page_155" id="Page_155">[Pg 155]</a></span></p>
+
+<p>Tuberculosis is one of the diseases which it is quite conceivable
+may be carried occasionally. The sputum of tubercular patients
+is very attractive to flies, and various workers, notably Graham-Smith,
+have found that <i>Musca domestica</i> may distribute the bacillus
+for several days after feeding on infected material.</p>
+
+<p>A type of purulent opthalmia which is very prevalent in Egypt
+is often said to be carried by flies. Nuttall and Jepson (1909)
+consider that the evidence regarding the spread of this disease by
+flies is conclusive and that the possibility of gonorrh&oelig;al secretions
+being likewise conveyed cannot be denied.</p>
+
+<p>Many studies have been published, showing a marked agreement
+between the occurrence of typhoid and other intestinal diseases
+and the prevalence of house-flies. The most clear-cut of these are
+the studies of the Army Commission appointed to investigate the
+cause of epidemics of enteric fever in the volunteer camps in the
+Southern United States during the Spanish-American War. Though
+their findings as presented by Vaughan (1909), have been quoted
+very many times, they are so germane to our discussion that they
+will bear repetition:</p>
+
+<p>"Flies swarmed over infected fecal matter in the pits and fed
+upon the food prepared for the soldiers in the mess tents. In some
+instances where lime had recently been sprinkled over the contents
+of the pits, flies with their feet whitened with lime were seen walking
+over the food." Under such conditions it is no wonder that "These
+pests had inflicted greater loss upon American soldiers than the arms
+of Spain."</p>
+
+<p>Similar conditions prevailed in South Africa during the Boer War.
+Seamon believes that very much of the success of the Japanese in
+their fight against Russia was due to the rigid precautions taken to
+prevent the spread of disease by these insects and other means.</p>
+
+<p>Veeder has pointed out that the characteristics of a typical fly-borne
+epidemic of typhoid are that it occurs in little neighborhood
+epidemics, extending by short leaps from house to house, without
+regard to water supply or anything else in common. It tends to
+follow the direction of prevailing winds (cf. the conclusions of Hindle
+and Merriman). It occurs during warm weather. Of course, when
+the epidemic is once well under way, other factors enter into its spread.</p>
+
+<p>In general, flies may be said to be the chief agency in the spread of
+typhoid in villages and camps. In cities with modern sewer systems
+they are less important, though even under the best of such conditions,<span class="pagenum"><a name="Page_156" id="Page_156">[Pg 156]</a></span>
+they are important factors. Howard has emphasized that in
+such cities there are still many uncared-for box privies and that, in
+addition, the deposition of feces overnight in uncared-for waste lots
+and alleys is common.</p>
+
+<p>Not only unicellular organisms, such as bacteria and protozoa,
+but also the eggs, embryos and larvæ of parasitic worms have been
+found to be transported by house-flies. Ransom (1911) has found
+that <i>Habronema muscæ</i>, a nematode worm often found in adult flies,
+is the immature stage of a parasite occurring in the stomach of the
+horse. The eggs or embryos passing out with the feces of the horse,
+are taken up by fly larvæ and carried over to the imago stage.</p>
+
+<p>Grassi (1883), Stiles (1889), Calandruccio (1906), and especially
+Nicoll (1911), have been the chief investigators of the ability of
+house-flies to carry the ova and embryos of human intestinal parasites.
+Graham-Smith (1913) summarizes the work along this line as follows:</p>
+
+<p>"It is evident from the investigations that have been quoted that
+house-flies and other species are greatly attracted to the ova of
+parasitic worms contained in feces and other materials, and make
+great efforts to ingest them. Unless the ova are too large they often
+succeed, and the eggs are deposited uninjured in their feces, in some
+cases up to the third day at least. The eggs may also be carried on
+their legs or bodies. Under suitable conditions, food and fluids
+may be contaminated with the eggs of various parasitic worms by flies,
+and in one case infection of the human subject has been observed.
+Feces containing tape-worm segments may continue to be a source of
+infection for as long as a fortnight. Up to the present, however,
+there is no evidence to show what part flies play in the dissemination
+of parasitic worms under natural conditions."</p>
+
+<p>Enough has been said to show that the house-fly must be dealt
+with as a direct menace to public health. Control measures are
+not merely matters of convenience but are of vital importance.</p>
+
+<p>Under present conditions the speedy elimination of the house-fly
+is impossible and the first thing to be considered is methods of protecting
+food and drink from contamination. The first of these
+methods is the thorough screening of doors and windows to prevent
+the entrance of flies. In the case of kitchen doors, the flies, attracted
+by odors, are likely to swarm onto the screen and improve the first
+opportunity for gaining an entrance. This difficulty can be largely
+avoided by screening-in the back porch and placing the screen door
+at one end rather than directly before the door.<span class="pagenum"><a name="Page_157" id="Page_157">[Pg 157]</a></span></p>
+
+<p>The use of sticky fly paper to catch the pests that gain entrance
+to the house is preferable to the various poisons often used. Of the
+latter, formalin (40 per cent formaldehyde) in the proportion of two
+tablespoonfuls to a pint of water is very efficient, if all other liquids
+are removed or covered, so that the flies must depend on the formalin
+for drink. The mixture is said to be made more attractive by the
+addition of sugar or milk, though we have found the plain solution
+wholly satisfactory, under proper conditions. It should be emphasized
+that this formalin mixture is not perfectly harmless, as so
+often stated. There are on record cases of severe and even fatal
+poisoning from the accidental drinking of solutions.</p>
+
+<p>When flies are very abundant in a room they can be most readily
+gotten rid of by fumigation with sulphur, or by the use of pure
+pyrethrum powder either burned or puffed into the air. Herrick
+(1913) recommends the following method: "At night all the doors
+and windows of the kitchen should be closed; fresh powder should
+be sprinkled over the stove, on the window ledges, tables, and in the
+air. In the morning flies will be found lying around dead or stupified.
+They may then be swept up and burned." This method has proved
+very efficaceous in some of the large dining halls in Ithaca.</p>
+
+<p>The writers have had little success in fumigating with the vapors
+of carbolic acid, or carbolic acid and gum camphor, although these
+methods will aid in driving flies from a darkened room.</p>
+
+<p>All of these methods are but makeshifts. As Howard has so well
+put it, "the truest and simplest way of attacking the fly problem
+is to prevent them from breeding, by the treatment or abolition of
+all places in which they can breed. To permit them to breed undisturbed
+and in countless numbers, and to devote all our energy to
+the problem of keeping them out of our dwellings, or to destroy them
+after they have once entered in spite of all obstacles, seems the
+wrong way to go about it."</p>
+
+<p>We have already seen that <i>Musca domestica</i> breeds in almost any
+fermenting organic material. While it prefers horse manure, it
+breeds also in human feces, cow dung and that of other animals,
+and in refuse of many kinds. To efficiently combat the insect,
+these breeding places must be removed or must be treated in some
+such way as to render them unsuitable for the development of the
+larvæ. Under some conditions individual work may prove effective,
+but to be truly efficient there must be extensive and thorough coöperative
+efforts.<span class="pagenum"><a name="Page_158" id="Page_158">[Pg 158]</a></span></p>
+
+<p>Manure, garbage, and the like should be stored in tight receptacles
+and carted away at least once a week. The manure may be carted
+to the fields and spread. Even in spread manure the larvæ may continue
+their development. Howard points out that "it often happens
+that after a lawn has been heavily manured in early summer the
+occupants of the house will be pestered with flies for a time, but
+finding no available breeding place these disappear sooner or later.
+Another generation will not breed in the spread manure."</p>
+
+<p>Hutchinson (1914) has emphasized that the larvæ of houseflies
+have deeply engrained the habit of migrating in the prepupal
+stage and has shown that this offers an important point of attack
+in attempts to control the pest. He has suggested that maggot
+traps might be developed into an efficient weapon in the warfare
+against the house-fly. Certain it is that the habit greatly simplifies the
+problem of treating the manure for the purpose of killing the larvæ.</p>
+
+<p>There have been many attempts to find some cheap chemical
+which would destroy fly larvæ in horse manure without injuring the
+bacteria or reducing the fertilizing values of the manure. The literature
+abounds in recommendations of kerosene, lime, chloride of lime,
+iron sulphate, and other substances, but none of them <span title="for have read has"><a name="AC_10" id="AC_10"></a>have</span> met the
+situation. The whole question has been gone into thoroughly by
+Cook, Hutchinson and Scales (1914), who tested practically all of the
+substances which have been recommended. They find that by far
+the most effective, economical, and practical of the substances is
+borax in the commercial form in which it is available throughout the
+country.</p>
+
+<p>"Borax increases the water-soluble nitrogen, ammonia and alkalinity
+of manure and apparently does not permanently injure the
+bacterial flora. The application of manure treated with borax at the
+rate of 0.62 pound per eight bushels (10 cubic feet) to soil does not
+injure the plants thus far tested, although its cumulative effect, if
+any, has not been determined."</p>
+
+<p>As their results clearly show that the substances so often recommended
+are inferior to borax, we shall quote in detail their directions
+for treating manure so as to kill fly eggs and maggots.</p>
+
+<p>"Apply 0.62 pound borax or 0.75 pound calcined colemanite to
+every 10 cubic feet (8 bushels) of manure immediately on its removal
+from the barn. Apply the borax particularly around the outer
+edges of the pile with a flour sifter or any fine sieve, and sprinkle two
+or three gallons of water over the borax-treated manure.<span class="pagenum"><a name="Page_159" id="Page_159">[Pg 159]</a></span></p>
+
+<p>"The reason for applying the borax to the fresh manure immediately
+after its removal from the stable is that the flies lay their eggs
+on the fresh manure, and borax, when it comes in contact with the
+eggs, prevents their hatching. As the maggots congregate at the
+outer edge of the pile, most of the borax should be applied there.
+The treatment should be repeated with each addition of fresh manure,
+but when the manure is kept in closed boxes, less frequent applications
+will be sufficient. When the calcined colemanite is available,
+it may be used at the rate of 0.75 pound per 10 cubic feet of manure,
+and is a cheaper means of killing the maggots. In addition to the
+application of borax to horse manure to kill fly larvæ, it may be
+applied in the same proportion to other manures, as well as to refuse
+and garbage. Borax may also be applied to the floors and crevices in
+barns, stables, markets, etc., as well as to street sweepings, and water
+should be added as in the treatment of horse manure. After estimating
+the amount of material to be treated and weighing the necessary
+amount of borax, a measure may be used which will hold the proper
+amount, thus avoiding the subsequent weighings.</p>
+
+<p>"While it can be safely stated that no injurious action will follow
+the application of manure treated with borax at the rate of 0.62
+pound for eight bushels, or even larger amounts in the case of some
+plants, nevertheless the borax-treated manure has not been studied
+in connection with the growth of all crops, nor has its cumulative
+effect been determined. It is therefore recommended that not more
+than 15 tons per acre of the borax-treated manure should be applied
+to the field. As truckmen use considerably more than this amount,
+it is suggested that all cars containing borax-treated manure be so
+marked, and that public-health officials stipulate in their directions
+for this treatment that not over 0.62 pound for eight bushels of manure
+be used, as it has been shown that larger amounts of borax will
+injure most plants. It is also recommended that all public-health
+officials and others, in recommending the borax treatment for killing
+fly eggs and maggots in manure, warn the public against the
+injurious effects of large amounts of borax on the growth of plants."</p>
+
+<p>"The amount of manure from a horse varies with the straw or
+other bedding used, but 12 or 15 bushels per week represent the
+approximate amount obtained. As borax costs from five to six
+cents per pound in 100-pound lots in Washington, it will make the
+cost of the borax practically one cent per horse, per day. And if
+calcined colemanite is purchased in large shipments the cost should
+be considerably less."<span class="pagenum"><a name="Page_160" id="Page_160">[Pg 160]</a></span></p>
+
+<p>Hodge (1910) has approached the problem of fly extermination
+from another viewpoint. He believes that it is practical to trap
+flies out of doors during the preoviposition period, when they are
+sexually immature, and to destroy such numbers of them that the
+comparatively few which survive will not be able to lay eggs in sufficient
+numbers to make the next generation a nuisance. To the end
+of capturing them in enormous numbers he has devised traps to be
+fitted over garbage cans, into stable windows, and connected with the
+kitchen window screens. Under some conditions this method of
+attack has proved very satisfactory.</p>
+
+<p>One of the most important measures for preventing the spread
+of disease by flies is the abolition of the common box privy. In
+villages and rural districts this is today almost the only type to be
+found. It is the chief factor in the spread of typhoid and other
+intestinal diseases, as well as intestinal parasites. Open and exposed
+to myriads of flies which not only breed there but which feed
+upon the excrement, they furnish ideal conditions for spreading contamination.
+Even where efforts are made to cover the contents
+with dust, or ashes, or lime, flies may continue to breed unchecked.
+Stiles and Gardner have shown that house-flies buried in a screened
+stand-pipe forty-eight inches under sterile sand came to the surface.
+Other flies of undetermined species struggled up through seventy-two
+inches of sand.</p>
+
+<p>So great is the menace of the ordinary box privy that a number of
+inexpensive and simple sanitary privies have been designed for use
+where there are not modern sewer systems. Stiles and Lumsden
+(1911) have given minute directions for the construction of one of the
+best types, and their bulletin should be obtained by those interested.</p>
+
+<p>Another precaution which is of fundamental importance in
+preventing the spread of typhoid, is that of disinfecting all discharges
+from patients suffering with the disease. For this purpose, quick-lime
+is the cheapest and is wholly satisfactory. In chamber vessels
+it should be used in a quantity equal to that of the discharge to be
+treated. It should be allowed to act for two hours. Air-slaked
+lime is of no value whatever. Chloride of lime, carbolic acid, or
+formalin may be used, but are more expensive. Other intestinal
+diseases demand similar precautions.</p>
+
+
+<p><a name="Stomoxys_calcitrans_the_stable-fly" id="Stomoxys_calcitrans_the_stable-fly"></a><b>Stomoxys calcitrans, the stable-fly</b>&mdash;It is a popular belief that
+house-flies bite more viciously just before a rain. As a matter of<span class="pagenum"><a name="Page_161" id="Page_161">[Pg 161]</a></span>
+fact, the true house-flies never bite, for their mouth-parts are not
+fitted for piercing. The basis of the misconception is the fact that a
+true biting fly, <i>Stomoxys calcitrans</i> (<a href="#Fig_110">fig.&nbsp;110</a>), closely resembling the
+house-fly, is frequently found in houses and may be driven in in
+greater numbers by muggy weather. From its usual habitat this
+fly is known as the "stable-fly" or, sometimes as the "biting house-fly."</p>
+
+<p><i>Stomoxys calcitrans</i> may be separated from the house-fly by the use
+of the key on p. 145. It may be more fully characterized as follows:</p>
+
+<p>The eyes of the male are separated by a distance equal to one-fourth
+of the diameter of the head, in the female by one-third. The
+frontal stripe is black, the cheeks and margins of the orbits silvery-white.
+The antennæ are black, the arista feathered on the upper
+side only. The proboscis is black, slender, fitted for piercing and
+projects forward in front of the head. The thorax is grayish, marked
+by four conspicuous, more or less complete black longitudinal stripes;
+the scutellum is paler; the macrochætæ are black. The abdomen is
+gray, dorsally with three brown spots on the second and third segments
+and a median spot on the fourth. These spots are more
+pronounced in the female. The legs are black, the pulvilli distinct.
+The wings are hyaline, the vein M<sub>1+2</sub> less sharply curved than in
+the house-fly, the apical cell being thus more widely open (cf. <a href="#Fig_110">fig.&nbsp;110</a>).
+Length 7 mm.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_110" id="Fig_110"></a>
+<a href="images/f110-full.png"><img src="images/f110.png" width="500" height="271" alt="110. Stomoxys calcitrans; adult, larva, puparium and details, (×5). After Howard." title="110. Stomoxys calcitrans; adult, larva, puparium and details, (×5). After Howard." /></a>
+<span class="caption">110. Stomoxys calcitrans; adult, larva, puparium and details, (×5). After Howard.</span>
+</div>
+
+<p>This fly is widely distributed, being found the world over. It was
+probably introduced into the United States, but has spread to all<span class="pagenum"><a name="Page_162" id="Page_162">[Pg 162]</a></span>
+parts of the country. Bishopp (1913) regards it as of much more
+importance as a pest of domestic animals in the grain belt than elsewhere
+in the United States. The life-history and habits of this
+species have assumed a new significance since it has been suggested
+that it may transmit the human diseases, infantile paralysis and
+pellagra. In this country, the most detailed study of the fly is that
+of Bishopp (1913) whose data regarding the life cycle are as follows:</p>
+
+<p>The eggs like those of the house-fly, are about one mm.
+in length. Under a magnifying glass they show a distinct furrow
+along one side. When placed on any moist substance they hatch
+in from one to three days after being deposited.</p>
+
+<p>The larva or maggots (<a href="#Fig_110">fig.&nbsp;110</a>) have the typical shape and actions
+of most maggots of the Muscid group. They can be distinguished
+from those of the house-fly as the stigma-plates are smaller, much
+further apart, with the slits less sinuous. Development takes place
+fairly rapidly when the proper food conditions are available and
+the growth is completed within eleven to thirty or more days.</p>
+
+<p>The pupa (<a href="#Fig_110">fig.&nbsp;110</a>), like that of related flies, undergoes its development
+within the contracted and hardened last larval skin, or puparium.
+This is elongate oval, slightly thicker towards the head end,
+and one-sixth to one-fourth of an inch in length. The pupal stage
+requires six to twenty days, or in cool weather considerably longer.</p>
+
+<p>The life-cycle of the stable-fly is therefore considerably longer
+than that of <i>Musca domestica</i>. Bishopp found that complete
+development might be undergone in nineteen days, but that the
+average period was somewhat longer, ranging from twenty-one to
+twenty-five days, where conditions are very favorable. The longest
+period which he observed was forty-three days, though his finding
+of full grown larvæ and pupæ in straw during the latter part of
+March, in Northern Texas, showed that development may require
+about three months, as he considered that these stages almost certainly
+developed from eggs deposited the previous December.</p>
+
+<p>The favorite breeding place, where available, seems to be straw or
+manure mixed with straw. It also breeds in great numbers in horse-manure,
+in company with <i>Musca domestica</i>.</p>
+
+<p>Newstead considers that in England the stable-fly hibernates in
+the pupal stage. Bishopp finds that in the southern part of the
+United States there is no true hibernation, as the adults have been
+found to emerge at various times during the winter. He believes
+that in the northern United States the winter is normally passed<span class="pagenum"><a name="Page_163" id="Page_163">[Pg 163]</a></span>
+in the larval and pupal stages, and that the adults which have been
+observed in heated stables in the dead of winter were bred out in
+refuse within the warm barns and were not hibernating adults.</p>
+
+<p>Graham-Smith (1913) states that although the stable-fly frequents
+stable manure, it is probably not an important agent in
+distributing the organisms of intestinal diseases. Bishopp makes the
+important observation that "it has never been found breeding in
+human excrement and does not frequent malodorous places, which
+are so attractive to the house-fly. Hence it is much less likely to
+carry typhoid and other germs which may be found in such places."</p>
+
+<p>Questions of the possible agency of <i>Stomoxys calcitrans</i> in the transmission
+of infantile paralysis and of pellagra, we shall consider later.</p>
+
+
+<p><a name="Other_arthropods_which_may_serve_as_simple_carriers_of_pathogenic_organisms" id="Other_arthropods_which_may_serve_as_simple_carriers_of_pathogenic_organisms"></a><b>Other arthropods which may serve as simple carriers of pathogenic
+organisms</b>&mdash;It should be again emphasized that any insect which
+has access to, and comes in contact with, pathogenic organisms
+and then passes to the food, or drink, or the body of man, may serve
+as a simple carrier of disease. In addition to the more obvious
+illustrations, an interesting one is the previously cited case of the
+transfer of <i>Dermatobia cyaniventris</i> by a mosquito (<a href="#Fig_81">fig.&nbsp;81-84</a>).
+Darling (1913) has shown that in the tropics, the omnipresent ants
+may be important factors in the spread of disease.<span class="pagenum"><a name="Page_164" id="Page_164">[Pg 164]</a></span></p>
+
+
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="CHAPTER_VI" id="CHAPTER_VI"></a>CHAPTER VI</h2>
+
+<h2>ARTHROPODS AS DIRECT INOCULATORS OF DISEASE GERMS</h2>
+
+
+<p>We have seen that any insect which, like the house-fly, has access
+to disease germs and then comes into contact with the food or drink
+of man, may serve to disseminate disease. Moreover, it has been
+clearly established that a contaminated insect, alighting upon
+wounded or abraded surfaces, may infect them. These are instances
+of mere accidental, mechanical transfer of pathogenic organisms.</p>
+
+<p>Closely related are the instances of direct inoculation of disease
+germs by insects and other arthropods. In this type, a blood-sucking
+species not only takes up the germs but, passing to a healthy
+individual, it inserts its contaminated mouth-parts and thus directly
+inoculates its victim. In other words, the disease is transferred
+just as blood poisoning may be induced by the prick of a contaminated
+needle, or as the laboratory worker may inoculate an experimental
+animal.</p>
+
+<p>Formerly, it was supposed that this method of the transfer of
+disease by arthropods was a very common one and many instances
+are cited in the earlier literature of the subject. It is, however,
+difficult to draw a sharp line between such cases and those in which,
+on the one hand, the arthropod serves as a mere passive carrier or,
+on the other hand, serves as an essential host of the pathogenic
+organism. More critical study of the subject has led to the belief
+that the importance of the rôle of arthropods as direct inoculators
+has been much overestimated.</p>
+
+<p>The principal reason for regarding this phase of the subject as
+relatively unimportant, is derived from a study of the habits of the
+blood-sucking species. It is found that, in general, they are intermittent
+feeders, visiting their hosts at intervals and then abstaining
+from feeding for a more or less extended period, while digesting their
+meal. In the meantime, most species of bacteria or of protozoan
+parasites with which they might have contaminated their mouth-parts,
+would have perished, through inability to withstand drying.</p>
+
+<p>In spite of this, it must be recognized that this method of transfer
+does occur and must be reckoned with in any consideration of the
+relations of insects to disease. We shall first cite some general
+illustrations and shall then discuss the rôle of fleas in the spreading
+of bubonic plague, an illustration which cannot be regarded as typical,
+since it involves more than mere passive carriage.<span class="pagenum"><a name="Page_165" id="Page_165">[Pg 165]</a></span></p>
+
+
+<h3><a name="Some_Illustrations_of_Direct_Inoculation_of_Disease_Germs_by_Arthropods" id="Some_Illustrations_of_Direct_Inoculation_of_Disease_Germs_by_Arthropods"></a><span class="smcap">Some Illustrations of Direct Inoculation of Disease Germs
+by Arthropods</span></h3>
+
+<p>In discussing poisonous arthropods, we have already emphasized
+that species which are of themselves innocuous to man, may occasionally
+introduce bacteria by their bite or sting and thus cause more or
+less severe secondary symptoms. That such cases should occur, is
+no more than is to be expected. The mouth-parts or the sting of
+the insect are not sterile and the chances of their carrying pyogenic
+organisms are always present.</p>
+
+<p>More strictly falling in the category of transmission of disease
+germs by direct inoculation are the instances where the insect, or
+related form, feeds upon a diseased animal and passes promptly to a
+healthy individual which it infects. Of such a nature are the following:</p>
+
+<p>Various species of biting flies are factors in the dissemination of
+anthrax, an infectious and usually fatal disease of animals and,
+occasionally, of man. That the bacteria with which the blood of
+diseased animals teem shortly before death might be transmitted
+by such insects has long been contended, but the evidence in support
+of the view has been unsatisfactory. Recently, Mitzmain (1914)
+has reported a series of experiments which show conclusively that the
+disease may be so conveyed by a horse-fly, <i>Tabanus striatus</i>, and by
+the stable-fly, <i>Stomoxys calcitrans</i>.</p>
+
+<p>Mitzmain's experiments were tried with an artificially infected
+guinea pig, which died of the disease upon the third day. The flies
+were applied two and one-half hours, to a few minutes, before the
+death of the animal. With both species the infection was successfully
+transferred to healthy guinea pigs by the direct method, in
+which the flies were interrupted while feeding on the sick animal.
+The evidence at hand does not warrant the conclusion that insect
+transmission is the rule in the case of this disease.</p>
+
+<p>The nagana, or tsetse-fly disease of cattle is the most virulent
+disease of domestic animals in certain parts of Africa. It is caused
+by a protozoan blood parasite, <i>Trypanosoma brucei</i>, which is conveyed
+to healthy animals by the bite of <i>Glossina morsitans</i> and possibly
+other species of tsetse-flies. The flies remain infective for
+forty-eight hours after feeding on a diseased animal. The insect
+also serves as an essential host of the parasite.</p>
+
+<p>Surra, a similar trypanosomiasis affecting especially horses and
+mules, occurs in southern Asia, Malaysia, and the Philippines where<span class="pagenum"><a name="Page_166" id="Page_166">[Pg 166]</a></span>
+the tsetse-flies are not to be found. It is thought to be spread by
+various species of blood-sucking flies belonging to the genera <i>Stomoxys</i>,
+<i>Hæmatobia</i>, and <i>Tabanus</i>. Mitzmain (1913) demonstrated that in
+the Philippines it is conveyed mechanically by <i>Tabanus striatus</i>.</p>
+
+<p>The sleeping sickness of man, in Africa, has also been supposed
+to be directly inoculated by one, or several, species of tsetse-flies.
+It is now known that the fly may convey the disease for a short
+time after feeding, but that there is then a latent period of from
+fourteen to twenty-one days, after which it again becomes infectious.
+This indicates that in the meantime the parasite has been undergoing
+some phase of its life-cycle and that the fly serves as an intermediate
+host. We shall therefore consider it more fully under that
+grouping.</p>
+
+<p>These are a few of the cases of direct inoculation which may be
+cited as of the simpler type. We shall next consider the rôle of the
+flea in the dissemination of the bubonic plague, an illustration
+complicated by the fact that the bacillus multiples within the insect
+and may be indirectly inoculated.</p>
+
+
+<h3><a name="The_Role_of_Fleas_in_the_Transmission_of_the_Plague" id="The_Role_of_Fleas_in_the_Transmission_of_the_Plague"></a><span class="smcap">The Rôle of Fleas in the Transmission of the Plague</span></h3>
+
+<p>The plague is a specific infectious disease caused by <i>Bacillus pestis</i>.
+It occurs in several forms, of which the bubonic and the pneumonic
+are the most common. According to Wyman, 80 per cent of the
+human cases are of the bubonic type. It is a disease which, under
+the name of oriental plague, the pest, or the black death, has ravaged
+almost from time immemorial the countries of Africa, Asia, and
+Europe. The record of its ravages are almost beyond belief. In 542
+A. D. it caused in one day ten thousand deaths in Constantinople.
+In the 14th century it was introduced from the East and prevailed
+throughout Armenia, Asia Minor, Egypt and Northern Africa and
+Europe. Hecker estimates that one-fourth of the population of
+Europe, or twenty-five million persons, died in the epidemic of that
+century. From then until the 17th century it was almost constantly
+present in Europe, the great plague of London, in 1665 killing 68,596
+out of a population of 460,000. Such an epidemic would mean for
+New York City a proportionate loss of over 600,000 in a single year.
+It is little wonder that in the face of such an appalling disaster suspicion
+and credulity were rife and the wildest demoralization ensued.</p>
+
+<p>During the 14th century the Jews were regarded as responsible
+for the disease, through poisoning wells, and were subjected to the<span class="pagenum"><a name="Page_167" id="Page_167">[Pg 167]</a></span>
+most incredible persecution and torture. In Milan the visitation
+of 1630 was credited to the so-called anointers,&mdash;men who were
+supposed to spread the plague by anointing the walls with magic
+ointment&mdash;and the most horrible tortures that human ingenuity
+could devise were imposed on scores of victims, regardless of rank
+or of public service (<a href="#Fig_112a">fig.&nbsp;112, a</a>). Manzoni's great historical novel,
+"The Betrothed" has well pictured conditions in Italy during this
+period.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_111" id="Fig_111"></a>
+<a href="images/f111-full.png"><img src="images/f111.png" width="350" height="217" alt="111. A contemporaneous engraving of the pest hospital in Vienna in 1679.
+After Peters." title="111. A contemporaneous engraving of the pest hospital in Vienna in 1679.
+After Peters." /></a>
+<span class="caption">111. A contemporaneous engraving of the pest hospital in Vienna in 1679.
+After Peters.</span>
+</div>
+
+<p>In modern times the plague is confined primarily to warm climates,
+a condition which has been brought about largely through general
+improvement in sanitary conditions.</p>
+
+<p>At present, the hotbed of the disease is India, where there were
+1,040,429 deaths in 1904 and where in a period of fifteen years,
+ending with January 1912, there were over 15,000,000 deaths. The
+reported deaths in that country for 1913 totaled 198,875.</p>
+
+<p>During the winter of 1910-11 there occurred in Manchuria and
+North China a virulent epidemic of the pneumonic plague which
+caused the death of nearly 50,000 people. The question as to its
+origin and means of spread will be especially referred to later.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_112a" id="Fig_112a"></a>
+<a href="images/f112a-full.png"><img src="images/f112a.png" width="350" height="257" alt="112 a. A medieval method of combating the plague. The persecution of the anointers in Milan in 1630. From a
+copy of &quot;Il processi originale degli untori&quot; in the library of Cornell University." title="112 a. A medieval method of combating the plague. The persecution of the anointers in Milan in 1630. From a
+copy of &quot;Il processi originale degli untori&quot; in the library of Cornell University." /></a>
+<span class="caption">112 a. A medieval method of combating the plague. The persecution of the anointers in Milan in 1630. From a
+copy of &quot;Il processi originale degli untori&quot; in the library of Cornell University.</span>
+</div><span class="pagenum"><a name="Page_168" id="Page_168">[Pg 168]</a></span>
+
+<p>Until recent years, the plague had not been known to occur in
+the New World but there were outbreaks in Brazil and Hawaii in
+1899, and in 1900 there occurred the first cases in San Francisco.<span class="pagenum"><a name="Page_169" id="Page_169">[Pg 169]</a></span>
+In California there were 125 cases in the period 1900-04; three cases
+in the next three years and then from May 1907 to March 1908,
+during the height of the outbreak, 170 cases. Since that time there
+have been only sporadic cases, the last case reported being in May
+1914. Still more recent were the outbreaks in the Philippine Islands,
+Porto Rico, and Cuba.</p>
+
+<p>On June 24, 1914, there was recognized a case of human plague
+in New Orleans. The Federal Health Service immediately took
+charge, and measures for the eradication of the disease were vigorously
+enforced. Up to October 10, 1914 there had been reported
+30 cases of the disease in man, and 181 cases of plague in rats.</p>
+
+<div class="figcenter" style="width: 450px;">
+<a href="images/f112b-full.png"><img src="images/f112b.png" width="450" height="225" alt="112 b. The modern method of combating the plague. A day&#39;s catch of rats in the fight
+against plague in San Francisco. Courtesy of Review of Reviews." title="112 b. The modern method of combating the plague. A day&#39;s catch of rats in the fight
+against plague in San Francisco. Courtesy of Review of Reviews." /></a>
+<span class="caption">112 b. The modern method of combating the plague. A day&#39;s catch of rats in the fight
+against plague in San Francisco. Courtesy of Review of Reviews.</span>
+</div>
+
+<p>The present-day methods of combating bubonic plague are well
+illustrated by the fight in San Francisco. Had it not been for the
+strenuous and radical anti-plague campaign directed by the United
+States Marine Hospital Service we might have had in our own
+country an illustration of what the disease can accomplish. On what
+newly acquired knowledge was this fight based?</p>
+
+<p>The basis was laid in 1894, when the plague bacillus was first
+discovered. All through the centuries, before and during the Christian
+era, down to 1894, the subject was enveloped in darkness and there
+had been a helpless, almost hopeless struggle in ignorance on the part
+of physicians, sanitarians, and public health officials against the
+ravages of this dread disease. Now its cause, method of propagation
+and means to prevent its spread are matters of scientific certainty.<span class="pagenum"><a name="Page_170" id="Page_170">[Pg 170]</a></span></p>
+
+<p>After the discovery of the causative organism, one of the first
+advances was the establishment of the identity of human plague
+and that of rodents. It had often been noted that epidemics of the
+human disease were preceded by great epizootics among rats and
+mice. So well established was this fact that with the Chinese,
+unusual mortality among these rodents was regarded as foretelling
+a visitation of the human disease. That there was more than an
+accidental connection between the two was obvious when Yersin,
+the discoverer of <i>Bacillus pestis</i>, announced that during an epidemic
+the rats found dead in the houses and in the streets almost always
+contain the bacillus in great abundance in their organs, and that many
+of them exhibit veritable buboes.</p>
+
+<p>Once it was established that the diseases were identical, the attention
+of the investigators was directed to a study of the relations
+between that of rats and of humans, and evidence accumulated to
+show that the bubonic plague was primarily a disease of rodents
+and that in some manner it was conveyed from them to man.</p>
+
+<p>There yet remained unexplained the method of transfer from rat
+to man. As long ago as the 16th century, Mercuralis suggested
+that house-flies were guilty of disseminating the plague but modern
+investigation, while blaming the fly for much in the way of spreading
+disease, show that it is an insignificant factor in this case.</p>
+
+<p>Search for blood-sucking insects which would feed on both rodents
+and man, and which might therefore be implicated, indicated that
+the fleas most nearly met the conditions. At first it was urged that
+rat fleas would not feed upon man and that the fleas ordinarily attacking
+man would not feed upon rats. More critical study of the habits
+of fleas soon showed that these objections were not well-founded.
+Especially important was the evidence that soon after the death of
+their host, rat fleas deserted its body and might then become a pest
+in houses where they had not been noticed before.</p>
+
+<p>Attention was directed to the fact that while feeding, fleas are in
+the habit of squirting blood from the anus and that in the case of those
+which had fed upon rats and mice dying of the plague, virulent plague
+bacilli were to be found in such blood. Liston (1905) even found,
+and subsequent investigations confirmed, that the plague bacilli
+multiply in the stomach of the insect and that thus the blood ejected
+was richer in the organisms than was that of the diseased animal.
+It was found that a film of this infected blood spread out under the
+body of the flea and that thus the bacilli might be inoculated by the
+bite of the insect and by scratching.<span class="pagenum"><a name="Page_171" id="Page_171">[Pg 171]</a></span></p>
+
+<p>Very recently, Bacot and Martin (1914) have paid especial
+attention to the question of the mechanism of the transmission of
+the plague bacilli by fleas. They believe that plague infested fleas
+regurgitate blood through the mouth, and that under conditions
+precluding the possibility of infection by dejecta, the disease may be
+thus transmitted. The evidence does not seem sufficient to establish
+that this is the chief method of transmission.</p>
+
+<p>Conclusive experimental proof that fleas transmit the disease is
+further available from a number of sources. The most extensive
+series of experiments is that of the English Plague Commission in
+India, which reported in 1906 that:</p>
+
+<p>On thirty occasions a healthy rat contracted plague in sequence
+of living in the neighborhood of a plague infected rat under circumstances
+which prevented the healthy rat coming in contact with
+either the body or excreta of the diseased animal.</p>
+
+<p>In twenty-one experiments out of thirty-eight, healthy rats living
+in flea-proof cages contracted plague when exposed to rat fleas
+(<i>Xenopsylla cheopis</i>), collected from rats dead or dying of septicæmic
+plague.</p>
+
+<p>Close contact of plague-infected with healthy animals, if fleas
+are excluded, does not give rise to an epizootic among the latter.
+As the huts were never cleaned out, close contact included contact
+with feces and urine of infected animals, and contact with, and eating
+of food contaminated with feces and urine of infected animals,
+as well as pus from open plague ulcers. Close contact of young,
+even when suckled by plague-infected mothers, did not give the
+disease to the former.</p>
+
+<p>If fleas are present, then the epizootic, once started, spreads from
+animal to animal, the rate of progress being in direct proportion to
+the number of fleas.</p>
+
+<p>Aerial infection was excluded. Thus guinea-pigs suspended in a
+cage two feet above the ground did not contract the disease, while
+in the same hut those animals allowed to run about and those placed
+two inches above the floor became infected. It had previously
+been found that a rat flea could not hop farther than about five
+inches.</p>
+
+<p>Guinea pigs and monkeys were placed in plague houses in pairs,
+both protected from soil contact infection and both equally exposed
+to aerial infection, but one surrounded with a layer of tangle-foot
+paper and the other surrounded with a layer of sand. The following
+observations were made:<span class="pagenum"><a name="Page_172" id="Page_172">[Pg 172]</a></span></p>
+
+<p>(<i>a</i>) Many fleas were caught in the tangle-foot, a certain proportion
+of which were found on dissection to contain in their stomachs
+abundant bacilli microscopically identical with plague bacilli. Out
+of eighty-five human fleas dissected only one contained these bacilli,
+while out of seventy-seven rat fleas twenty-three were found thus
+infected.</p>
+
+<p>(<i>b</i>) The animals surrounded with tangle-foot in no instance
+developed plague, while several (24 per cent) of the non-protected
+animals died of the disease.</p>
+
+<p>Thus, the experimental evidence that fleas transmit the plague
+from rat to rat, from rats to guinea pigs, and from rats to monkeys
+is indisputable. There is lacking direct experimental proof of its
+transfer from rodents to man but the whole chain of indirect evidence
+is so complete that there can be no doubt that such a transfer
+does occur so commonly that in the case of bubonic plague it must
+be regarded as the normal method.</p>
+
+<p>Rats are not the only animals naturally attacked by the plague
+but as already suggested, it occurs in various other rodents. In
+California the disease has spread from rats to ground squirrels
+(<i>Otospermophilus beecheyi</i>), a condition readily arising from the
+frequency of association of rats with the squirrels in the neighborhood
+of towns, and from the fact that the two species of fleas found
+on them are also found on rats. While the danger of the disease
+being conveyed from squirrels to man is comparatively slight, the
+menace in the situation is that the squirrels may become a more or
+less permanent reservoir of the disease and infect rats, which may
+come into more frequent contact with man.</p>
+
+<p>The tarbagan (<i>Arctomys bobac</i>), is a rodent found in North Manchuria,
+which is much prized for its fur. It is claimed that this animal
+is extremely susceptible to the plague and there is evidence to
+indicate that it was the primary source of the great outbreak of
+pneumonic plague which occurred in Manchuria and North China
+during the winter of 1910-11.</p>
+
+<p>Of fleas, any species which attacks both rodents and man may be
+an agent in the transmission of the plague. We have seen that in
+India the species most commonly implicated is the rat flea, <i>Xenopsylla
+cheopis</i>, (= <i>L&oelig;mopsylla</i> or <i>Pulex cheopis</i>) (<a href="#Fig_89">fig.&nbsp;89</a>). This species has
+also been found commonly on rats in San Francisco. The cat flea,
+<i>Ctenocephalus felis</i>, the dog flea, <i>Ctenocephalus canis</i>, the human flea,
+<i>Pulex irritans</i>, the rat fleas, <i>Ceratophyllus fasciatus</i> and <i>Ctenopsyllus
+musculi</i> have all been shown to meet the conditions.<span class="pagenum"><a name="Page_173" id="Page_173">[Pg 173]</a></span></p>
+
+<p>But, however clear the evidence that fleas are the most important
+agent in the transfer of plague, it is a mistake fraught with danger
+to assume that they are the only factor in the spread of the disease.
+The causative organism is a bacillus and is not dependent upon any
+insect for the completion of its development.</p>
+
+<p>Therefore, any blood-sucking insect which feeds upon a plague
+infected man or animal and then passes to a healthy individual,
+conceivably might transfer the bacilli. Verjbitski (1908) has shown
+experimentally that bed-bugs may thus convey the disease. Hertzog
+found the bacilli in a head-louse, <i>Pediculus humanus</i>, taken from a
+child which had died from the plague, and McCoy found them in a
+louse taken from a plague-infected squirrel. On account of their
+stationary habits, the latter insects could be of little significance in
+spreading the disease.</p>
+
+<p>Contaminated food may also be a source of danger. While this
+source, formerly supposed to be the principal one, is now regarded as
+unimportant, there is abundant experimental evidence to show that
+it cannot be disregarded. It is believed that infection in this way
+can occur only when there is some lesion in the alimentary canal.</p>
+
+<p>Still more important is the proof that in pneumonic plague the
+patient is directly infective and that the disease is spread from man
+to man without any intermediary. Especially conclusive is the
+evidence obtained by Drs. Strong and Teague during the Manchurian
+epidemic of 1910-11. They found that during coughing, in pneumonic
+plague cases, even when sputum visible to the naked eye is
+not expelled, plague bacilli in large numbers may become widely
+disseminated into the surrounding air. By exposing sterile plates
+before patients who coughed a single time, very numerous colonies
+of the bacillus were obtained.</p>
+
+<p>But the great advance which has been made rests on the discovery
+that bubonic plague is in the vast majority of cases transmitted
+by the flea. The pneumonic type forms a very small percentage
+of the human cases and even with it, the evidence indicates that the
+original infection is derived from a rodent through the intermediary
+of the insect.</p>
+
+<p>So modern prophylactic measures are directed primarily against
+the rat and fleas. Ships coming from infected ports are no longer
+disinfected for the purpose of killing the plague germs, but are fumigated
+to destroy the rats and the fleas which they might harbor.
+When anchored at infected ports, ships must observe strenuous<span class="pagenum"><a name="Page_174" id="Page_174">[Pg 174]</a></span>
+precautions to prevent the ingress of rats. Cargo must be inspected
+just before being brought on board, in order to insure its freedom from
+rats. Even lines and hawsers must be protected by large metal discs
+or funnels, for rats readily run along a rope to reach the ship. Once
+infested, the ship must be thoroughly fumigated, not only to avoid
+carrying the disease to other ports but to obviate an outbreak on
+board.</p>
+
+<p>When an epidemic begins, rats must be destroyed by trapping
+and poisoning. Various so-called biological poisons have not proved
+practicable. Sources of food supply should be cut off by thorough
+cleaning up, by use of rat-proof garbage cans and similar measures.
+Hand in hand with these, must go the destruction of breeding places,
+and the rat-proofing of dwellings, stables, markets, warehouses, docks
+and sewers. All these measures are expensive, and a few years ago
+would have been thought wholly impossible to put into practice
+but now they are being enforced on a large scale in every fight against
+the disease.</p>
+
+<p>Rats and other rodents are regularly caught in the danger zone
+and examined for evidence of infection, for the sequence of the epizootic
+and of the human disease is now understood. In London, rats
+are regularly trapped and poisoned in the vicinity of the principal
+docks, to guard against the introduction of infected animals in shipping.
+During the past six years infected rats have been found
+yearly, thirteen having been found in 1912. In Seattle, Washington,
+seven infected rats were found along the water front in October, 1913,
+and infected ground squirrels are still being found in connection with
+the anti-plague measures in California.</p>
+
+<p>The procedure during an outbreak of the human plague was well
+illustrated by the fight in San Francisco. The city was districted,
+and captured rats, after being dipped in some fluid to destroy the fleas,
+were carefully tagged to indicate their source, and were sent to the
+laboratory for examination. If an infected rat was found, the officers
+in charge of the work in the district involved were immediately
+notified by telephone, and the infected building was subjected to a
+thorough fumigation. In addition, special attention was given to
+all the territory in the four contiguous blocks.</p>
+
+<p>By measures such as these, this dread scourge of the human race
+is being brought under control. Incidentally, the enormous losses
+due to the direct ravages of rats are being obviated and this alone
+would justify the expenditure many times over of the money and
+labor involved in the anti-rat measures.<span class="pagenum"><a name="Page_175" id="Page_175">[Pg 175]</a></span></p>
+
+
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="CHAPTER_VII" id="CHAPTER_VII"></a>CHAPTER VII</h2>
+
+<h2>ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC ORGANISMS</h2>
+
+
+<p>We now have to consider the cases in which the arthropod acts
+as the essential host of a pathogenic organism. In other words,
+cases in which the organism, instead of being passively carried or
+merely accidentally inoculated by the bite of its carrier, or vector, is
+taken up and undergoes an essential part of its development within
+the arthropod.</p>
+
+<p>In some cases, the sexual cycle of the parasite is undergone in the
+arthropod, which then serves as the <i>definitive</i> or
+<i>primary host</i>. In other cases, it is the asexual stage
+of the parasite which is undergone, and the arthropod
+then acts as the <i>intermediate host</i>. This distinction
+is often overlooked and all the cases incorrectly
+referred to as those in which the insect or other
+arthropod acts as intermediate host.</p>
+
+<div class="figcenter" style="width: 150px;"><a name="Fig_113" id="Fig_113"></a>
+<a href="images/f113-full.png"><img src="images/f113.png" width="150" height="472" alt="113. Dipylidium
+caninum. The
+double pored
+tapeworm of the
+dog." title="113. Dipylidium
+caninum. The
+double pored
+tapeworm of the
+dog." /></a>
+<span class="caption">113. Dipylidium
+caninum. The
+double pored
+tapeworm of the
+dog.</span>
+</div>
+
+<p>We have already emphasized that this is the most
+important way in which insects may transmit disease,
+for without them the particular organisms concerned
+could never complete their development. Exterminate
+the arthropod host and the life cycle of the
+parasite is broken, the disease is exterminated.</p>
+
+<p>As the phenomenon of alternation of generations,
+as exhibited by many of the parasitic protozoa, is a
+complicated one and usually new to the student, we
+shall first take up some of the grosser cases illustrated
+by certain parasitic worms. There is the additional
+reason that these were the first cases known of arthropod
+transmission of pathogenic organisms.</p>
+
+
+<h3><a name="Insects_as_Intermediate_Hosts_of_Tapeworms" id="Insects_as_Intermediate_Hosts_of_Tapeworms"></a><span class="smcap">Insects as Intermediate Hosts of Tapeworms</span></h3>
+
+<p>A number of tapeworms are known to undergo their sexual stage
+in an insect or other arthropod. Of these at least two are occasional
+parasites of man.</p>
+
+<p><i>Dipylidium caninum</i> (figs. <a href="#Fig_113">113</a>&nbsp;and&nbsp;<a href="#Fig_114">114</a>), more generally known as
+<i>Taenia cucumerina</i> or <i>T. elliptica</i>, is the commonest intestinal parasite
+of pet dogs and cats. It is occasionally found as a human parasite,
+70 per cent of the cases reported being in young children.<span class="pagenum"><a name="Page_176" id="Page_176">[Pg 176]</a></span></p>
+
+<div class="figleft" style="width: 250px;"><a name="Fig_114" id="Fig_114"></a>
+<a href="images/f114-full.png"><img src="images/f114.png" width="250" height="264" alt="114. Dipylidium caninum.
+Rostrum evaginated and
+invaginated. After
+Blanchard." title="114. Dipylidium caninum.
+Rostrum evaginated and
+invaginated. After
+Blanchard." /></a>
+<span class="caption">114. Dipylidium caninum.
+Rostrum evaginated and
+invaginated. After
+Blanchard.</span>
+</div>
+
+<p>In 1869, Melnikoff found in a dog louse, <i>Trichodectes canis</i>, some
+peculiar bodies which Leuckart identified as the larval form of this
+tapeworm. The worm is, however, much more
+common in dogs and cats than is the skin parasite,
+and hence it appears that the <i>Trichodectes</i>
+could not be the only intermediate host. In
+1888, Grassi found that it could also develop
+in the cat and dog fleas, <i>Ctenocephalus felis</i>
+and <i>C. canis</i>, and in the human flea, <i>Pulex
+irritans</i>.</p>
+
+<div class="figright" style="width: 200px;"><a name="Fig_115" id="Fig_115"></a>
+<a href="images/f115-full.png"><img src="images/f115.png" width="200" height="161" alt="115. Dipylidium caninum.
+Immature cysticercoid.
+After Grassi and Rovelli." title="115. Dipylidium caninum.
+Immature cysticercoid.
+After Grassi and Rovelli." /></a>
+<span class="caption">115. Dipylidium caninum.
+Immature cysticercoid.
+After Grassi and Rovelli.</span>
+</div>
+
+<p>The eggs, scattered among the hairs of the
+dog or cat, are ingested by the insect host and
+in its body cavity they develop into pyriform
+bodies, about 300µ in length, almost entirely destitute of a bladder,
+but in the immature stage provided with a caudal appendage (<a href="#Fig_115">fig.&nbsp;115</a>).
+Within the pear-shaped body (<a href="#Fig_116">fig.&nbsp;116</a>) are the invaginated head and
+suckers of the future tapeworm. This larval
+form is known as a cysticercoid, in contradistinction
+to the bladder-like cysticercus of many
+other cestodes. It is often referred to in literature
+as <i>Cryptocystis trichodectis</i> Villot.</p>
+
+<p>As many as fifty of the cysticercoids have
+been found in the body cavity of a single flea.
+When the dog takes up an infested flea or louse,
+by biting itself, or when the cat licks them up, the
+larvæ quickly develop into tapeworms, reaching sexual maturity in
+about twenty days in the intestine of their host. Puppies and
+kittens are quickly infested when suckling a flea-infested mother, the
+developing worms having been found in the intestines of puppies not
+more than five or six days old.</p>
+
+<div class="figleft" style="width: 200px;"><a name="Fig_116" id="Fig_116"></a>
+<a href="images/f116-full.png"><img src="images/f116.png" width="200" height="138" alt="116. Dipylidium caninum.
+Cysticercoid. After
+Villet." title="116. Dipylidium caninum.
+Cysticercoid. After
+Villet." /></a>
+<span class="caption">116. Dipylidium caninum.
+Cysticercoid. After
+Villet.</span>
+</div>
+
+<p>Infestation of human beings occurs only
+through accidental ingestion of an infested flea.
+It is natural that such cases should occur largely
+in children, where they may come about in
+some such way as illustrated in the accompanying
+figures&nbsp;<a href="#Fig_117">117</a> and&nbsp;<a href="#Fig_118">118</a>.</p>
+
+<p><i>Hymenolepis diminuta</i>, very commonly living in the intestine
+of mice and rats, is also known to occur in man. Its cysticercoid
+develops in the body cavity of a surprising range of meal-infesting
+insects. Grassi and Rovelli (abstract in Ransom, 1904) found it in the<span class="pagenum"><a name="Page_177" id="Page_177">[Pg 177]</a></span>
+larvæ and adult of a moth, <i>Asopia farinalis</i>, in the earwig, <i>Anisolabis
+annulipes</i>, the Tenebrionid beetles <i>Akis spinosa</i> and <i>Scaurus striatus</i>.
+Grassi considers that the lepidopter is the normal intermediate
+host. The insect takes
+up the eggs scattered by rats
+and mice. It has been experimentally
+demonstrated that
+man may develop the tapeworm
+by swallowing infested
+insects. Natural infection
+probably occurs by ingesting
+such insects with cereals, or
+imperfectly cooked foods.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_117" id="Fig_117"></a>
+<a href="images/f117-full.png"><img src="images/f117.png" width="400" height="290" alt="117. One way in which Dipylidium infection in
+children may occur. After Blanchard." title="117. One way in which Dipylidium infection in
+children may occur. After Blanchard." /></a>
+<span class="caption">117. One way in which Dipylidium infection in
+children may occur. After Blanchard.</span>
+</div>
+
+<p><i>Hymenolepis lanceolata</i>, a parasite of geese and ducks, has been
+reported once for man. The supposed cysticercoid occurs in various
+small crustaceans of the family Cyclopidæ.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_118" id="Fig_118"></a>
+<a href="images/f118-full.png"><img src="images/f118.png" width="450" height="353" alt="118. The probable method by which Dipylidium infection usually occurs." title="118. The probable method by which Dipylidium infection usually occurs." /></a>
+<span class="caption">118. The probable method by which Dipylidium infection usually occurs.</span>
+</div><p><span class="pagenum"><a name="Page_178" id="Page_178">[Pg 178]</a></span></p>
+
+<p>Several other cestode parasites of domestic animals are believed
+to develop their intermediate stage in certain arthropods. Among
+these may be mentioned:</p>
+
+<p><i>Choanotænia infundibulformis</i>, of chickens, developing in the house-fly
+(Grassi and Rovelli);</p>
+
+<p><i>Davainea cesticillus</i>, of chickens, in some lepidopter or coleopter
+(Grassi and Rovelli);</p>
+
+<p><i>Hymenolepis anatina</i>, <i>H. gracilis</i>, <i>H. sinuosa</i>, <i>H. coronula</i> and
+<i>Fimbriaria fasciolaris</i>, all occurring in ducks, have been reported as
+developing in small aquatic crustaceans. In these cases, cysticercoids
+have been found which, on account of superficial characters,
+have been regarded as belonging to the several species, but direct
+experimental evidence is scant.</p>
+
+
+<h3><a name="Arthropods_as_Intermediate_Hosts_of_Nematode_Worms" id="Arthropods_as_Intermediate_Hosts_of_Nematode_Worms"></a><span class="smcap">Arthropods as Intermediate Hosts of Nematode Worms</span></h3>
+
+
+<p><a name="Filariasis_and_Mosquitoes" id="Filariasis_and_Mosquitoes"></a><b>Filariasis and Mosquitoes</b>&mdash;A number of species of Nematode
+worms belonging to the genus <i>Filaria</i>, infest man and other vertebrates
+and in the larval condition are to be found in the blood.
+Such infestation is known as <i>filariasis</i>. The sexually mature worms
+are to be found in the blood, the lymphatics, the mesentery and subcutaneous
+connective tissue. In the cases best studied it has been
+found that the larval forms are taken up by mosquitoes and undergo
+a transformation before they can attain maturity in man.</p>
+
+<p>The larvæ circulating in the blood are conveniently designated
+as microfilariæ. In this stage they are harmless and only one species,
+<i>Filaria bancrofti</i>, appears to be of any great pathological significance
+at any stage.</p>
+
+<p><i>Filaria bancrofti</i> in its adult state, lives in the lymphatics of man.
+Though often causing no injury it has been clearly established that
+they and their eggs may cause various disorders due to stoppage
+of the lymphatic trunks (<a href="#Fig_119">fig.&nbsp;119</a>). Manson lists among other effects,
+abscess, varicose groin glands, lymph scrotum, chyluria, and elephantiasis.</p>
+
+<p>The geographical distribution of this parasite is usually given as
+coextensive with that of elephantiasis, but it is by no means certain
+that it is the only cause of this disease and so actual findings of the
+parasites are necessary. Manson reports that it is "an indigenous
+parasite in almost every country throughout the tropical and subtropical
+world, as far north as Spain in Europe and Charlestown in<span class="pagenum"><a name="Page_179" id="Page_179">[Pg 179]</a></span>
+the United States, and as far south as Brisbane in Australia." In
+some sections, fully 50 per cent of the natives are infested. Labredo
+(1910) found 17.82 per cent infestation in Havana.</p>
+
+<div class="figcenter" style="width: 317px;"><a name="Fig_119" id="Fig_119"></a>
+<a href="images/f119-full.png"><img src="images/f119.png" width="317" height="390" alt="119. Elephantiasis in Man. From &quot;New
+Sydenham Society&#39;s Atlas.&quot;" title="119. Elephantiasis in Man. From &quot;New
+Sydenham Society&#39;s Atlas.&quot;" /></a>
+<span class="caption">119. Elephantiasis in Man. From &quot;New
+Sydenham Society&#39;s Atlas.&quot;</span>
+</div>
+
+<p>The larval forms of <i>Filaria bancrofti</i> were first discovered in 1863,
+by Demarquay, in a case of chylous dropsy. They were subsequently
+noted under similar conditions, by several workers, and by
+Wücherer in the urine of twenty-eight cases of tropical chyluria,
+but in 1872 Lewis found that the blood of man was the normal
+habitat, and gave them the name <i>Filaria sanguinis hominis</i>. The
+adult worm was found in 1876
+by Bancroft, and in 1877,
+Cobbold gave it the name <i>Filaria
+bancrofti</i>. It has since been
+found repeatedly in various parts
+of the lymphatic system, and its
+life-history has been the subject
+of detailed studies by Manson
+(1884), Bancroft (1899), Low
+(1900), Grassi and Noé (1900),
+Noé (1901) and Fülleborn (1910).</p>
+
+<p>The larvæ as they exist in
+the circulating blood, exhibit a
+very active wriggling movement,
+without material progression.
+They may exist in enormous
+numbers, as many as five or
+six hundred swarming in a
+single drop of blood. This is the more surprising when we consider
+that they measure about 300µ × 8µ, that is, their width is
+equal to the diameter of the red blood corpuscle of their host and
+their length over thirty-seven times as great.</p>
+
+<p>Their organs are very immature and the structure obscure. When
+they have quieted down somewhat in a preparation it may be seen
+that at the head end there is a six-lipped and very delicate prepuce,
+enclosing a short "fang" which may be suddenly exserted and
+retracted. Completely enclosing the larva is a delicate sheath,
+which is considerably longer than the worm itself. To enter into
+further details of anatomy is beyond the scope of this discussion
+and readers interested are referred to the work of Manson and of
+Fülleborn.<span class="pagenum"><a name="Page_180" id="Page_180">[Pg 180]</a></span></p>
+
+<p>One of the most surprising features of the habits of these larvæ
+is the periodicity which they exhibit in their occurrence in the peripheral
+blood. If a preparation be made during the day time there
+may be no evidence whatever of filarial infestation, whereas a preparation
+from the same patient taken late in the evening or during
+the night may be literally swarming with the parasites. Manson
+quotes Mackenzie as having brought out the further interesting
+fact that should a "filarial subject be made to sleep during the day
+and remain awake at night, the periodicity is reversed; that is to say,
+the parasites come into the blood during the day and disappear from
+it during the night." There have been numerous attempts to explain
+this peculiar phenomenon of periodicity but in spite of objections
+which have been raised, the most plausible remains that of Manson,
+who believes that it is an adaptation correlated with the life-habits
+of the liberating agent of the parasite, the mosquito.</p>
+
+<p>The next stages in the development of <i>Filaria nocturna</i> occur in
+mosquitoes, a fact suggested almost simultaneously by Bancroft
+and Manson in 1877, and first demonstrated by the latter very soon
+thereafter. The experiments were first carried out with <i>Culex
+quinquefasciatus</i> (= <i>fatigans</i>) as a host, but it is now known that a
+number of species of mosquitoes, both anopheline and culicine, may
+serve equally well.</p>
+
+<p>When the blood of an infested individual is sucked up and reaches
+the stomach of such a mosquito, the larvæ, by very active movements,
+escape from their sheaths and within a very few hours actively migrate
+to the body cavity of their new host and settle down primarily
+in the thoracic muscles. There in the course of sixteen to twenty
+days they undergo a metamorphosis of which the more conspicuous
+features are the formation of a mouth, an alimentary canal and a
+trilobed tail. At the same time there is an enormous increase in
+size, the larvæ which measured .3 mm. in the blood becoming 1.5 mm.
+in length. This developmental period may be somewhat shortened
+in some cases and on the other hand may be considerably extended.
+The controlling factor seems to be the one of temperature.</p>
+
+<p>The transformed larvæ then reenter the body cavity and finally
+the majority of them reach the interior of the labium (<a href="#Fig_120">fig.&nbsp;120</a>). A
+few enter the legs and antennæ, and the abdomen, but these are
+wanderers which, it is possible, may likewise ultimately reach the
+labium, where they await the opportunity to enter their human host.<span class="pagenum"><a name="Page_181" id="Page_181">[Pg 181]</a></span></p>
+
+<p>It was formerly supposed that when the infested mosquito punctured
+the skin of man, the mature larvæ were injected into the circulation.
+The manner in which this occurred was not obvious, for
+when the insect feeds it inserts only the stylets, the labium itself
+remaining on the surface of the skin. Fülleborn has cleared up the
+question by showing that at this time the filariæ escape and, like
+the hookworm, actively bore into the skin of their new host.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_120" id="Fig_120"></a>
+<a href="images/f120-full.png"><img src="images/f120.png" width="500" height="343" alt="120. Filaria in the muscles and labium of Culex. After Blanchard." title="120. Filaria in the muscles and labium of Culex. After Blanchard." /></a>
+<span class="caption">120. Filaria in the muscles and labium of Culex. After Blanchard.</span>
+</div>
+
+<p>Once entered, they migrate to the lymphatics and there quickly
+become sexually mature. The full grown females measure 85-90 mm.
+in length by .24-.28 mm. in diameter, while the males are less than
+half this size, being about 40 mm. by .1 mm. Fecundation occurs
+and the females will be found filled with eggs in various stages of
+development, for they are normally viviparous.</p>
+
+<p><i>Filaria philippinensis</i> is reported by Ashburn and Craig (1907) as
+a common blood filaria in the Philippine Islands. As they describe
+it, it differs from <i>Filaria bancrofti</i> primarily in that it does not exhibit
+periodicity. Its development has been found to occur in <i>Culex
+quinquefasciatus</i>, where it undergoes metamorphosis in about fourteen
+or fifteen days. There is doubt as to the species being distinct from
+<i>bancrofti</i>.</p>
+
+<p>Several other species occur in man and are thought to be transferred
+by various insects, among which have been mentioned Tabanidæ
+and tsetse-flies, but there is no experimental proof in support
+of such conjectures.<span class="pagenum"><a name="Page_182" id="Page_182">[Pg 182]</a></span></p>
+
+<div class="figleft" style="width: 200px;"><a name="Fig_121" id="Fig_121"></a>
+<a href="images/f121-full.png"><img src="images/f121.png" width="200" height="343" alt="121. Dracunculus
+medinensis; female;
+mouth; embryo.
+After Bastian and
+Leuckart." title="121. Dracunculus
+medinensis; female;
+mouth; embryo.
+After Bastian and
+Leuckart." /></a>
+<span class="caption">121. Dracunculus
+medinensis; female;
+mouth; embryo.
+After Bastian and
+Leuckart.</span>
+</div>
+
+<p><i>Filaria immitis</i> is a dangerous parasite of the dog, the adult worm
+living in the heart and veins of this animal. It is one of the species
+which has been clearly shown to undergo its development in the
+mosquito, particularly in <i>Anopheles maculipennis</i> and <i>Aedes calopus</i>
+(= Stegomyia). The larval form occurs in the peripheral blood,
+especially at night. When taken up by mosquitoes they differ from
+<i>Filaria bancrofti</i> in that they undergo their development in the
+Malpighian tubules rather than in the thoracic muscles. In
+about twelve days they have completed their growth in the tubules,
+pierce the distal end, and pass to the labium. This species occurs
+primarily in China and Japan, but is also found in Europe and in the
+United States. It is an especially favorable species for studying
+the transformations in the mosquito.</p>
+
+<p><i>Filariæ</i> are also commonly found in birds, and in this country
+this is the most available source of laboratory material. We have
+found them locally (Ithaca, N. Y.) in the blood of
+over sixty per cent of all the crows examined, at
+any season of the year, and have also found them
+in English sparrows.</p>
+
+<p>In the crows, they often occur in enormous
+numbers, as many as two thousand having been
+found in a single drop of the blood of the most
+heavily infested specimen examined. For study, a
+small drop of blood should be mounted on a clean
+slide and the coverglass rung with vaseline or oil
+to prevent evaporation. In this way they can
+be kept for hours.</p>
+
+<p>Permanent preparations may be made by
+spreading out the blood in a film on a perfectly
+clean slide and staining. This is easiest done by touching the fresh
+drop of blood with the end of a second slide which is then held at
+an angle of about 45° to the first slide and drawn over it without
+pressure. Allow the smear to dry in the air and stain in the usual
+way with hæmatoxylin.</p>
+
+
+<h3><a name="Other_Nematode_Parasites_of_Man_and_Animals_Developing_in_Arthropods" id="Other_Nematode_Parasites_of_Man_and_Animals_Developing_in_Arthropods"></a><span class="smcap">Other Nematode Parasites of Man and Animals Developing
+in Arthropods</span></h3>
+
+<p><i>Dracunculus medinensis</i> (<a href="#Fig_121">fig.&nbsp;121</a>), the so-called guinea-worm, is
+a nematode parasite of man which is widely distributed in tropical
+Africa, Asia, certain parts of Brazil and is occasionally imported
+into North America.<span class="pagenum"><a name="Page_183" id="Page_183">[Pg 183]</a></span></p>
+
+<div class="figright" style="width: 175px;"><a name="Fig_122" id="Fig_122"></a>
+<a href="images/f122-full.png"><img src="images/f122.png" width="175" height="303" alt="122. Cyclops, the intermediate host of
+Dracunculus." title="122. Cyclops, the intermediate host of
+Dracunculus." /></a>
+<span class="caption">122. Cyclops, the intermediate host of
+Dracunculus.</span>
+</div>
+
+<p>The female worm is excessively long and slender, measuring nearly
+three feet in length and not more than one-fifteenth of an inch in
+diameter. It is found in the subcutaneous connective tissue and when
+mature usually migrates to some part of the leg.
+Here it pierces the skin and there is formed a small
+superficial ulcer through which the larvæ reach the
+exterior after bursting the body of the mother.</p>
+
+<p>Fedtschenko (1879) found that when these larvæ
+reach the water they penetrate the carapace of the
+little crustacean, <i>Cyclops</i> (<a href="#Fig_122">fig.&nbsp;122</a>). Here they molt
+several times and undergo a metamorphosis. Fedtschenko,
+in Turkestan, found that these stages required
+about five weeks, while Manson who confirmed these
+general results, found that eight or nine weeks were
+required in the cooler climate of England.</p>
+
+<p>Infection of the vertebrate host probably occurs through swallowing
+infested cyclops in drinking water. Fedtschenko was unable to
+demonstrate this experimentally and objection has been raised against
+the theory, but Leiper (1907), and Strassen (1907) succeeded in infesting
+monkeys by feeding them on cyclops containing the larvæ.</p>
+
+<p><i>Habronema muscæ</i> is a worm which has long been known in its
+larval stage, as a parasite of the house-fly. Carter found them in
+33 per cent of the house-flies examined in Bombay during July, 1860,
+and since that time they have been shown to be very widely distributed.
+Italian workers reported them in 12 per cent to 30 per cent
+of the flies examined. Hewitt reported finding it rarely in England.
+In this country it was first reported by Leidy who found it in about
+20 per cent of the flies examined at Philadelphia, Pa. Since then it
+has been reported by several American workers. We have found it
+at Ithaca, N. Y., but have not made sufficient examinations to justify
+stating percentage. Ransom (1913) reports it in thirty-nine out of
+one hundred and thirty-seven flies, or 28 per cent.</p>
+
+<div class="figcenter" style="width: 500px;">
+<a href="images/f123-full.png"><img src="images/f123.png" width="500" height="491" alt="123. An Echinorhynchid, showing the spinose retractile proboscis." title="123. An Echinorhynchid, showing the spinose retractile proboscis." /></a>
+<span class="caption">123. An Echinorhynchid, showing the spinose retractile proboscis.</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_124" id="Fig_124"></a>
+<a href="images/f124-full.png"><img src="images/f124.png" width="500" height="309" alt="124. June beetle (Lachnosterna). Larva." title="124. June beetle (Lachnosterna). Larva." /></a>
+<span class="caption">124. June beetle (Lachnosterna). Larva.</span>
+</div>
+
+<p>Until very recently the life-history of this parasite was unknown
+but the thorough work of Ransom (1911, 1913) has shown clearly
+that the adult stage occurs in the stomach of horses. The embryos,
+produced by the parent worms in the stomach of the horse, pass
+out with the feces and enter the bodies of fly larvæ which are developing
+in the manure. In these they reach their final stage of larval
+development at about the time the adult flies emerge from the pupal
+stage. In the adult fly they are commonly found in the head.<span class="pagenum"><a name="Page_184" id="Page_184">[Pg 184]</a></span>
+frequently in the proboscis, but they occur also in the thorax and
+abdomen. Infested flies are accidentally swallowed by horses and
+the parasite completes its development to maturity in the stomach of
+its definitive host.<span class="pagenum"><a name="Page_185" id="Page_185">[Pg 185]</a></span></p>
+
+<p><i>Gigantorhynchus hirudinaceus</i> (= <i>Echinorhynchus gigas</i>) is a common
+parasite of the pig and has been reported as occurring in man.
+The adult female is 20-35 cm. long and 4-9 mm. in diameter.
+It lacks an alimentary canal and is provided with a strongly spined
+protractile rostrum, by means of which it attaches to the intestinal
+mucosa of its host.</p>
+
+<p>The eggs are scattered with the feces of the host and are taken
+up by certain beetle larvæ. In Europe the usual intermediate hosts
+are the larvæ of the cockchafer, <i>Melolontha vulgaris</i>, or of the flower
+beetle, <i>Cetonia aurata</i>. Stiles has shown that in the United States
+the intermediate host is the larva of the June bug, <i>Lachnosterna</i>
+(<a href="#Fig_124">fig.&nbsp;124</a>). It is probable that several of the native species serve in
+this capacity.</p>
+
+<p>A number of other nematode parasites of birds and mammals
+have been reported as developing in arthropods but here, as in the
+case of the cestodes, experimental proof is scant. The cases above
+cited are the better established and will serve as illustrations.<span class="pagenum"><a name="Page_186" id="Page_186">[Pg 186]</a></span></p>
+
+
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="CHAPTER_VIII" id="CHAPTER_VIII"></a>CHAPTER VIII</h2>
+
+<h2>ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC
+PROTOZOA</h2>
+
+
+<h3><a name="Mosquitoes_and_Malaria" id="Mosquitoes_and_Malaria"></a><span class="smcap">Mosquitoes and Malaria</span></h3>
+
+<p>Under the name of malaria is included a group of morbid symptoms
+formerly supposed to be due to a miasm or bad air, but now
+known to be caused by protozoan parasites of the genus <i>Plasmodium</i>,
+which attack the red blood corpuscles. It occurs in paroxysms,
+each marked by a chill, followed by high fever and sweating. The
+fever is either intermittent or remittent.</p>
+
+<p>There are three principal types of the disease, due to different
+species of the parasite. They are:</p>
+
+<p>1. The benign-tertian, caused by <i>Plasmodium vivax</i>, which undergoes
+its schizogony or asexual cycle in the blood in forty-eight hours
+or even less. This type of the disease,&mdash;characterized by fever
+every two days, is the most wide-spread and common.</p>
+
+<p>2. The quartan fever is due to the presence of <i>Plasmodium
+malariæ</i>, which has an asexual cycle of seventy-two hours, and therefore
+the fever recurs every three days. This type is more prevalent
+in temperate and sub-tropical regions, but appears to be rare everywhere.</p>
+
+<p>3. The sub-tertian "æstivo-autumnal," or "pernicious" fever
+is caused by <i>Plasmodium falciparum</i>. Schizogony usually occurs
+in the internal organs, particularly in the spleen, instead of in the
+peripheral circulation, as is the case of the tertian and quartan forms.
+The fever produced is of an irregular type and the period of schizogony
+has not been definitely determined. It is claimed by some that the
+variations are due to different species of malignant parasites.</p>
+
+<p>It is one of the most wide-spread of human diseases, occurring
+in almost all parts of the world, except in the polar regions and in
+waterless deserts. It is most prevalent in marshy regions.</p>
+
+<p>So commonplace is malaria that it causes little of the dread
+inspired by most of the epidemic diseases, and yet, as Ross says,
+it is perhaps the most important of human diseases. Figures regarding
+its ravages are astounding. Celli estimated that in Italy it
+caused an average annual mortality of fifteen thousand, representing
+about two million cases. In India alone, according to Ross (1910)<span class="pagenum"><a name="Page_187" id="Page_187">[Pg 187]</a></span>
+"it has been officially estimated to cause a mean annual death-rate
+of five per thousand; that is, to kill every year, on the average, one
+million one hundred and thirty thousand." In the United States
+it is widespread and though being restricted as the country develops,
+it still causes enormous losses. During the year 1911, "in Alabama
+alone there were seventy thousand cases and seven hundred and
+seventy deaths." The weakening effects of the disease, the invasion
+of other diseases due to the attacks of malaria, are among the very
+serious results, but they cannot be estimated.</p>
+
+<p>Not only is there direct effect on man, but the disease has been one
+of the greatest factors in retarding the development of certain regions.
+Everywhere pioneers have had to face it, and the most fertile regions
+have, in many instances been those most fully dominated by it.
+Herrick (1903) has presented an interesting study of its effects on
+the development of the southern United States and has shown that
+some parts, which are among the most fertile in the world, are
+rendered practically uninhabitable by the ravages of malaria. Howard
+(1909) estimates that the annual money loss from the disease
+in the United States is not less than $100,000,000.</p>
+
+<p>It was formerly supposed that the disease was due to a miasm,
+to a noxious effluvia, or infectious matter rising in the air from
+swamps. In other words its cause was, as the name indicated
+"mal aria," and the deep seated fear of night air is based largely on
+the belief that this miasm was given off at night. Its production
+was thought to be favored by stirring of the soil, dredging operations
+and the like.</p>
+
+<p>The idea of some intimate connection between malaria and
+mosquitoes is not a new one. According to Manson, Lancisi noted
+that in some parts of Italy the peasants for centuries have believed
+that malaria is produced by the bite of mosquitoes. Celli states
+that one not rarely hears from such peasants the statement that
+"In such a place, there is much fever, because it is full of mosquitoes."
+Koch points out that in German East Africa the natives call malaria
+and the mosquito by the same name, <i>Mbù</i>. The opinion was not
+lacking support from medical men. Celli quotes passages from the
+writings of the Italian physician, Lancisi, which indicate that he
+favored the view in 1717.</p>
+
+<p>Dr. Josiah Nott is almost universally credited with having supported
+the theory, in 1848, but as we have already pointed out
+his work has been misinterpreted. The statements of Beauperthuy,
+(1853) were more explicit.<span class="pagenum"><a name="Page_188" id="Page_188">[Pg 188]</a></span></p>
+
+<p>The clearest early presentation of the circumstantial evidence in
+favor of the theory of mosquito transmission was that of A. F. A.
+King, an American physician, in 1883. He presented a series of
+epidemiological data and showed "how they may be explicable by
+the supposition that the mosquito is the real source of the disease,
+rather than the inhalation or cutaneous absorption of a marsh vapor."
+We may well give the space to summarizing his argument here for
+it has been so remarkably substantiated by subsequent work:</p>
+
+<p>1. Malaria, like mosquitoes, affects by preference low and moist
+localities, such as swamps, fens, jungles, marshes, etc.</p>
+
+<p>2. Malaria is hardly ever developed at a lower temperature
+than 60° Fahr., and such a temperature is necessary for the development
+of the mosquito.</p>
+
+<p>3. Mosquitoes, like malaria, may both accumulate in and be
+obstructed by forests lying in the course of winds blowing from
+malarious localities.</p>
+
+<p>4. By atmospheric currents malaria and mosquitoes are alike
+capable of being transported for considerable distances.</p>
+
+<p>5. Malaria may be developed in previously healthy places by
+turning up the soil, as in making excavations for the foundation of
+houses, tracks for railroads, and beds for canals, because these operations
+afford breeding places for mosquitoes.</p>
+
+<p>6. In proportion as countries, previously malarious, are cleared
+up and thickly settled, periodical fevers disappear, because swamps
+and pools are drained so that the mosquito cannot readily find a place
+suitable to deposit her eggs.</p>
+
+<p>7. Malaria is most dangerous when the sun is down and the
+danger of exposure after sunset is greatly increased by the person
+exposed sleeping in the night air. Both facts are readily explicable
+by the mosquito malaria theory.</p>
+
+<p>8. In malarial districts the use of fire, both indoors and to those
+who sleep out, affords a comparative security against malaria, because
+of the destruction of mosquitoes.</p>
+
+<p>9. It is claimed that the air of cities in some way renders the
+poison innocuous, for, though a malarial disease may be raging outside,
+it does not penetrate far into the interior. We may easily
+conceive that mosquitoes, while invading cities during their nocturnal
+pilgrimages will be so far arrested by walls and houses, as well as
+attracted by lights in the suburbs, that many of them will in this
+way be prevented from penetrating "far into the interior."<span class="pagenum"><a name="Page_189" id="Page_189">[Pg 189]</a></span></p>
+
+<p>10. Malarial diseases and likewise mosquitoes are most prevalent
+toward the latter part of summer and in the autumn.</p>
+
+<p>11. Various writers have maintained that malaria is arrested by
+canvas curtains, gauze veils and mosquito nets and have recommended
+the rise of mosquito curtains, "through which malaria can
+seldom or never pass." It can hardly be conceived that these
+intercept marsh-air but they certainly do protect from mosquitoes.</p>
+
+<p>12. Malaria spares no age, but it affects infants much less
+frequently than adults, because young infants are usually carefully
+housed and protected from mosquito inoculation.</p>
+
+<p>Correlated with the miasmatic theory was the belief that some
+animal or vegetable organism which lived in marshes, produced
+malaria, and frequent searches were made for it. Salisbury (1862)
+thought this causative organism to be an alga, of the genus <i>Palmella</i>;
+others attributed it to certain fungi or bacteria.</p>
+
+<p>In 1880, the French physician, Laveran, working in Algeria,
+discovered an am&oelig;boid organism in the blood of malarial patients
+and definitely established the parasitic nature of this disease. Pigmented
+granules had been noted by Meckel as long ago as 1847, in
+the spleen and blood of a patient who had died of malaria, and his
+observations had been repeatedly verified, but the granules had been
+regarded as degeneration products, and the fact that they occurred
+in the body of a foreign organism had been overlooked.</p>
+
+<p>Soon after the discovery of the parasites in the blood, Gerhardt
+(1884) succeeded in transferring the disease to healthy individuals
+by inoculation of malarious blood, and thus proved that it is a true
+infection. This was verified by numerous experimenters and it
+was found that inoculation with a very minute quantity of the diseased
+blood would not only produce malaria but the particular type
+of disease.</p>
+
+<p>Laveran traced out the life cycle of the malarial parasite as it
+occurs in man. The details as we now know them and as they are
+illustrated by the accompanying <a href="#Fig_125">figure&nbsp;125</a>, are as follows:</p>
+
+<p>The infecting organism or <i>sporozoite</i>, is introduced into the circulation,
+penetrates a red blood corpuscle, and forms the am&oelig;boid
+<i>schizont</i>. This lives at the expense of the corpuscle and as it develops
+there are deposited in its body scattered black or reddish black
+particles. These are generally called melanin granules, but are
+much better referred to as hæmozoin, as they are not related to<span class="pagenum"><a name="Page_190" id="Page_190">[Pg 190]</a></span>
+melanin. The hæmozoin is the most conspicuous part of the parasite,
+a feature of advantage in diagnosing from unstained preparations.</p>
+
+<div class="figcenter" style="width: 325px;"><a name="Fig_125" id="Fig_125"></a>
+<a href="images/f125-full.png"><img src="images/f125.png" width="325" height="335" alt="125. Life cycle of the malaria parasite. Adapted from Leuckart&#39;s chart,
+by Miss Anna Stryke." title="125. Life cycle of the malaria parasite. Adapted from Leuckart&#39;s chart,
+by Miss Anna Stryke." /></a>
+<span class="caption">125. Life cycle of the malaria parasite. Adapted from Leuckart&#39;s chart,
+by Miss Anna Stryke.</span>
+</div>
+
+<p>As the schizont matures, its nucleus breaks up into a number of
+daughter nuclei, each with a rounded mass of protoplasm about it,
+and finally the corpuscles are broken down and these rounded bodies
+are liberated in the plasma as <i>merozoites</i>. These merozoites infect
+new corpuscles and thus the asexual cycle is continued. The malarial
+paroxysm is coincident with sporulation.</p>
+
+<p>As early as Laveran's time it was known that under conditions
+not yet determined there are to be found in the blood of malarious
+patients another phase of the parasite, differing in form according
+to the type of the disease. In the pernicious type these appear as
+large, crescent-shaped organisms which have commonly been called
+"crescents." We now know that these are sexual forms.<span class="pagenum"><a name="Page_191" id="Page_191">[Pg 191]</a></span></p>
+
+<p>When the parasite became known there immediately arose speculations
+as to the way in which it was transferred from man to man.
+It was thought by some that in nature it occurred as a free-living
+am&oelig;ba, and that it gained access to man through being taken up
+with impure water. However, numerous attempts to infect healthy
+persons by having them drink or inhale marsh water, or by injecting
+it into their circulation resulted in failure, and influenced by Leuckart's
+and Melnikoff's work on <i>Dipylidium</i>, that of Fedtschenko on <i>Dracunculus</i>,
+and more especially by that of Manson on <i>Filaria</i>, search was
+made for some insect which might transfer the parasite.</p>
+
+<p>Laveran had early suggested that the rôle of carrier might be
+played by the mosquito, but Manson first clearly formulated the
+hypothesis, and it was largely due to his suggestions that Ross in
+India, undertook to solve the problem. With no knowledge of the
+form or of the appearance in this stage, or of the species of mosquito
+concerned, Ross spent almost two and a half years of the most arduous
+work in the search and finally in August, 1897, seventeen years
+after the discovery of the parasite in man, he obtained his first
+definite clue. In dissecting a "dappled-winged mosquito," "every
+cell was searched and to my intense disappointment nothing whatever
+was found, until I came to the insect's stomach. Here, however,
+just as I was about to abandon the examination, I saw a very delicate
+circular cell, apparently lying amongst the ordinary cells of the organ
+and scarcely distinguishable from them. On looking further,
+another and another similar object presented itself. I now focused
+the lens carefully on one of these, and found that it contained a few
+minute granules of some black substance, exactly like the pigment of
+the parasite of malaria. I counted altogether twelve of these cells
+in the insect."</p>
+
+<p>Further search showed that "the contents of the mature pigment
+cells did not consist of clear fluid but of a multitude of delicate,
+thread-like bodies which on the rupture of the parent cell, were poured
+into the body cavity of the insect. They were evidently spores."</p>
+
+<p>With these facts established, confirmation and extension of
+Ross's results quickly followed, from many different sources. We
+cannot trace this work in detail but will only point out that much
+of the credit is due to the Italian workers, Grassi, Bignami, and
+Bastianelli, and to Koch and Daniels.</p>
+
+<p>It had already been found that when fresh blood was mounted and
+properly protected against evaporation, a peculiar change occurred<span class="pagenum"><a name="Page_192" id="Page_192">[Pg 192]</a></span>
+in these crescents after about half an hour's time. From certain
+of them there were pushed out long whip-like processes which moved
+with a very active, lashing movement. The parasite at this stage
+is known as the "flagellated body." Others, differing somewhat in
+details of structure, become rounded but do not give off "flagella."</p>
+
+<p>The American worker, MacCallum (1897), in studying bird
+malaria as found in crows, first recognized the true nature of these
+bodies. He regarded them as sexual forms and believed that the
+so-called flagella played the part of spermatozoa. Thus, the "flagellated
+body" is in reality a <i>microgametoblast</i>, producing <i>microgametes</i>,
+or the male sexual element, while the others constitute the <i>macrogametes</i>,
+or female elements.</p>
+
+<p>It was found that when blood containing these sexual forms was
+sucked up by an Anopheline mosquito and taken into its stomach, a
+microgamete penetrated and fertilized a macrogamete in a way
+analogous to what takes place in the fertilization of the egg in higher
+forms. The resultant, mobile organism is known as the <i>migratory
+ookinete</i>. In this stage the parasite bores through the epithelial
+lining of the "stomach" (mid-intestine) of the mosquito and becomes
+encysted under the muscle layers. Here the <i>oocyst</i>, as it is now
+known, matures and breaks up into the body cavity and finally
+its products come to lie in the salivary glands of the mosquito. Ten
+to twelve days are required for these changes, after which the mosquito
+is infective, capable of introducing the parasite with its saliva,
+when feeding upon a healthy person.</p>
+
+<p>Thus the malarial parasite is known to have a double cycle, an
+alternation of generations, of which the asexual stage is undergone in
+man, the sexual in certain species of mosquitoes. The mosquito is
+therefore the definitive host rather than the <i>intermediate</i>, as usually
+stated.</p>
+
+<p>The complicated cycle may be made clearer by the diagram of
+Miss Stryke (1912) which, by means of a double-headed mosquito
+(<a href="#Fig_126">fig.&nbsp;126</a>) endeavors to show how infection takes place through the
+biting of the human victim, (at A), in whom asexual multiplication
+then takes place, and how the sexual stages, taken up at B in the
+diagram, are passed in the body of the mosquito.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_126" id="Fig_126"></a>
+<a href="images/f126-full.png"><img src="images/f126.png" width="450" height="567" alt="126. Life cycle of the malarial parasite. After Miss Anna Stryke." title="126. Life cycle of the malarial parasite. After Miss Anna Stryke." /></a>
+<span class="caption">126. Life cycle of the malarial parasite. After Miss Anna Stryke.</span>
+</div>
+
+<p>The experimental proof that mosquitoes of the Anopheline group
+are necessary agents in the transmission of malaria was afforded in
+1900 when two English physicians, Drs. Sambon and Low lived for
+the three most malarial months in the midst of the Roman Campagna,<span class="pagenum"><a name="Page_193" id="Page_193">[Pg 193]</a></span>
+a region famous for centuries as a hot-bed of malaria. The two
+experimenters moved about freely throughout the day, exposed
+themselves to rains and all kinds of weather, drank marsh water,
+slept exposed to the marsh air, and, in short, did everything which
+was supposed to cause malaria, except that they protected themselves
+thoroughly from mosquito bites, retiring at sunset to a mosquito-proof<span class="pagenum"><a name="Page_194" id="Page_194">[Pg 194]</a></span>
+hut. Though they took no quinine and all of their neighbors
+suffered from malaria, they were absolutely free from the disease.</p>
+
+<p>To complete the proof, mosquitoes which had fed in Rome on
+malarious patients were sent to England and allowed to bite two
+volunteers, one of them Dr. Manson's own son, who had not been
+otherwise exposed to the disease. Both of these gentlemen contracted
+typical cases of malaria and the parasites were to be found in
+abundance in their blood.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_127" id="Fig_127"></a>
+<a href="images/f127-full.png"><img src="images/f127.png" width="400" height="489" alt="127. Eggs of Anopheles. After Howard." title="127. Eggs of Anopheles. After Howard." /></a>
+<span class="caption">127. Eggs of Anopheles. After Howard.</span>
+</div>
+
+<p>Since that time there have been many practical demonstrations
+of the fact that malaria is transmitted exclusively by the bite of
+mosquitoes and that the destruction
+of the mosquitoes means the
+elimination of the disease.</p>
+
+<p>We have said that the malarial
+parasite is able to undergo its
+development only in certain
+species of mosquitoes belonging
+to the Anopheline group. It is
+by no means certain that all of
+this group even, are capable of
+acting as the definitive host of
+the parasites, and much careful
+experiment work is still needed
+along this line. In the United
+States, several species have been
+found to be implicated, <i>Anopheles
+quadrimaculatus</i> and <i>Anopheles
+crucians</i> being the most common. The characteristics of these species
+and the distinctions between them and other mosquitoes will be
+discussed in <a href="#CHAPTER_XII">Chapter XII</a>.</p>
+
+<p>In antimalarial work it is desirable to distinguish the anopheline
+mosquitoes from the culicine species in all stages. The following
+tabulation presents the more striking distinctions between the groups
+as represented in the United States.</p>
+
+
+<div class="center">
+<table border="0" cellpadding="4" cellspacing="0" summary="">
+<tr><td align="center"><i>Anopheles</i></td><td align="center"><i>Culex, Aedes, etc.</i></td></tr>
+<tr>
+<td align="left">
+<p><i>Eggs</i>: Laid singly in small
+numbers upon the surface of the
+water. Eggs lie upon their sides
+and float by means of lateral
+<span class="pagenum"><a name="Page_195" id="Page_195">[Pg 195]</a></span>expansions (<a href="#Fig_127">fig.&nbsp;127</a>).</p>
+</td>
+<td align="left">
+<p>Deposited in clumps in the
+form of a raft (Culex group) or
+deposited singly in the water or
+on the ground in places which
+may later be submerged.</p>
+</td>
+</tr>
+<tr>
+<td align="left">
+<p><i>Larva</i>: When at rest floats in
+a horizontal position beneath the
+surface film. No respiratory
+tube but instead a flattened
+area on the eighth abdominal
+segment into which the two
+spiracles open (<a href="#Fig_128a">fig.&nbsp;128</a>).</p>
+</td>
+<td align="left">
+<p>When at rest (with few exceptions)
+floats suspended in an
+oblique or vertical position, or
+more rarely nearly horizontal,
+with the respiratory tube in
+contact with the surface film
+(<a href="#Fig_128a">fig.&nbsp;128</a>).</p>
+</td>
+</tr>
+<tr>
+<td align="left">
+<p><i>Adults</i>: Palpi in both sexes
+nearly or quite as long as the
+proboscis. Proboscis projecting
+forward nearly on line with the
+axis of the body. When at rest
+on a vertical wall the body is
+usually held at an angle with the
+vertical (<a href="#Fig_128b">fig.&nbsp;128</a>). Wings frequently
+spotted (<a href="#Fig_130">fig.&nbsp;130</a>).</p>
+</td>
+<td align="left">
+<p>Palpi short in the female, in
+the male usually elongate. Proboscis
+projects forward at an
+angle with the axis of the body.
+When at rest on a vertical wall
+the body is usually held parallel
+or the tip of the abdomen inclined
+towards the wall (<a href="#Fig_128b">fig.&nbsp;128</a>).
+Wings usually not spotted.</p>
+</td>
+</tr>
+</table></div>
+
+<div class="figcenter" style="width: 425px;"><a name="Fig_128a" id="Fig_128a"></a>
+<a href="images/f128a-full.png"><img src="images/f128a.png" width="425" height="142" alt="128. (a) Normal position of the larvæ
+of Culex and Anopheles in
+the water. Culex, left; Anopheles,
+middle; Culex pupa,
+right hand figure." title="128. (a) Normal position of the larvæ
+of Culex and Anopheles in
+the water. Culex, left; Anopheles,
+middle; Culex pupa,
+right hand figure." /></a>
+<span class="caption">128. (<i>a</i>)&nbsp;Normal position of the larvæ
+of Culex and Anopheles in
+the water. Culex, left; Anopheles,
+middle; Culex pupa,
+right hand figure.</span>
+</div>
+
+<p>These malarial-bearing species are essentially domesticated
+mosquitoes. They develop in any accumulation of water which
+stands for a week or more.
+Ponds, puddles, rain barrels,
+horse troughs, cess-pools, cans,
+even the foot-prints of animals
+in marshy ground may
+afford them breeding places.</p>
+
+<div class="figcenter" style="width: 150px;"><a name="Fig_128b" id="Fig_128b"></a>
+<a href="images/f128b-full.png"><img src="images/f128b.png" width="150" height="402" alt="128. (b) Normal
+position of
+Culex and
+Anopheles on
+the wall." title="128. (b) Normal
+position of
+Culex and
+Anopheles on
+the wall." /></a>
+<span class="caption">128. (<i>b</i>)&nbsp;Normal
+position of
+Culex and
+Anopheles on
+the wall.</span>
+</div>
+
+<p>It is clear from what has been said regarding the life cycle of the
+malarial parasite that the mosquito is harmless if not itself diseased.
+Hence malarial-bearing species may abound in the
+neighborhood where there is no malaria, the disease
+being absent simply because the mosquitoes are uninfected.
+Such a locality is potentially malarious and
+needs only the introduction of a malarial patient who is
+exposed to the mosquitoes. It is found that such patients
+may harbor the parasites in their blood long after they
+are apparently well and thus may serve as a menace,
+just as do the so-called typhoid carriers. In some
+malarious regions as high as 80-90 per cent of the natives
+are such malaria-carriers and must be reckoned with in
+antimalaria measures.</p>
+
+<p>Based upon our present day knowledge of the life cycle
+of the malarial parasite the fight against the disease<span class="pagenum"><a name="Page_196" id="Page_196">[Pg 196]</a></span>
+becomes primarily a problem in economic entomology,&mdash;it is a question
+of insect control, in its broadest interpretation.</p>
+
+<div class="figcenter" style="width: 350px;">
+<a href="images/f129-full.png"><img src="images/f129.png" width="350" height="682" alt="129. Larva of Anopheles. After Howard." title="129. Larva of Anopheles. After Howard." /></a>
+<span class="caption">129. Larva of Anopheles. After Howard.</span>
+</div>
+
+<p>The lines of defence and offence
+against the disease as outlined by
+Boyce (1909) are:</p>
+
+<div class="blockquot"><div class="hanging">
+<p>1. Measures to avoid the reservoir
+(man):</p>
+
+<div class="hanging">
+<p>Segregation.</p>
+
+<p>Screening of patients.</p>
+</div>
+
+<p>2. Measures to avoid Anopheles:</p>
+
+<div class="hanging">
+<p>Choice of suitable locality,
+when possible.</p>
+
+<p>Screening of houses and
+porches.</p>
+
+<p>Sleeping under mosquito nets.</p>
+</div>
+
+<p>3. Measures to exterminate the
+Anopheles:</p>
+
+<div class="hanging">
+<p>Use of natural enemies.</p>
+
+<p>Use of culicides, oiling ponds,
+etc.</p>
+
+<p>Drainage and scavenging to
+destroy breeding places.</p>
+
+<p>Enforcement of penalties for
+harboring larvæ or keeping
+stagnant water.</p>
+
+<p>Educational methods.</p>
+</div>
+
+<p>4. Systematic treatment with quinine to exterminate the parasites.</p>
+</div></div>
+
+
+<h3><a name="Mosquitoes_and_Yellow_Fever" id="Mosquitoes_and_Yellow_Fever"></a><span class="smcap">Mosquitoes and Yellow Fever</span></h3>
+
+<p>Yellow fever was until recently one of the most dreaded of epidemic
+diseases. It is an acute, specific and infectious disease, non-contagious
+in character but occurring in epidemics, or endemics,
+within a peculiarly limited geographical area. It is highly fatal,
+but those who recover are generally immune from subsequent attacks.</p>
+
+<p>It is generally regarded as an American disease, having been
+found by Cortez, in Mexico, and being confined principally to the
+American continents and islands. It also occurs in Africa and attempts
+have been made to show that it was originally an African
+disease but there is not sufficient evidence to establish this view.<span class="pagenum"><a name="Page_197" id="Page_197">[Pg 197]</a></span></p>
+
+<p>There have been many noted outbreaks in the United States.
+Boston suffered from it in 1691 and again in 1693; New York in
+1668 and as late as 1856; Baltimore in 1819. In 1793 occurred the
+great epidemic in Philadelphia, with a death rate of one in ten of the
+population. In the past century it was present almost every year in
+some locality of our Southern States, New Orleans being the greatest
+sufferer. In the latter city there were 7848 deaths from the disease
+in 1853, 4854 in 1858, and 4046 in 1878. The last notable outbreak
+was in 1905. Reed and Carroll (1901) estimated that during the
+period from 1793 to 1900 there had not been less than 500,000 cases
+in the United States.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_130" id="Fig_130"></a>
+<a href="images/f130-full.png"><img src="images/f130.png" width="500" height="377" alt="130. Anopheles quadrimaculatus, male and female, (×3&frac12;). After Howard." title="130. Anopheles quadrimaculatus, male and female, (×3&frac12;). After Howard." /></a>
+<span class="caption">130. Anopheles quadrimaculatus, male and female, (×3&frac12;). After Howard.</span>
+</div>
+
+<p>As in the case of the plague, the most stringent methods of control
+proved ineffective and helplessness, almost hopelessness marked
+the great epidemics. A vivid picture of conditions is that given by
+Mathew Cary, 1793 (quoted by Kelly, 1906) in "A Short Account of
+the Malignant Fever Lately Prevalent in Philadelphia."</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_131" id="Fig_131"></a>
+<a href="images/f131-full.png"><img src="images/f131.png" width="500" height="534" alt="131. Anopheles punctipennis. Female, (×4). After Howard." title="131. Anopheles punctipennis. Female, (×4). After Howard." /></a>
+<span class="caption">131. Anopheles punctipennis. Female, (×4). After Howard.</span>
+</div>
+
+<p>"The consternation of the people of Philadelphia at this period
+was carried beyond all bounds. Dismay and affright were visible<span class="pagenum"><a name="Page_198" id="Page_198">[Pg 198]</a></span>
+in the countenance of almost every person. Of those who remained,
+many shut themselves in their houses and were afraid to walk the
+streets. * * * The corpses of the most respectable citizens,
+even those who did not die of the epidemic, were carried to the grave
+on the shafts of a chair (chaise), the horse driven by a negro, unattended
+by friends or relative, and without any sort of ceremony.
+People hastily shifted their course at the sight of a hearse coming
+toward them. Many never walked on the footpath, but went into
+the middle of the streets to avoid being infected by passing by houses
+wherein people had died. Acquaintances and friends avoided each
+other in the streets and only signified their regard by a cold nod.
+The old custom of shaking hands fell into such disuse that many
+shrunk back with affright at even the offer of the hand. A person<span class="pagenum"><a name="Page_199" id="Page_199">[Pg 199]</a></span>
+with a crape, or any appearance of mourning was shunned like a
+viper. And many valued themselves highly on the skill and address
+with which they got to the windward of every person they met.
+Indeed, it is not probable that London, at the last stage of the plague,
+exhibited stronger marks of terror than were to be seen in Philadelphia
+from the 24th or 25th of August until pretty late in September."</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_132" id="Fig_132"></a>
+<a href="images/f132-full.png"><img src="images/f132.png" width="500" height="511" alt="132. Anopheles crucians. Female (×4). After Howard." title="132. Anopheles crucians. Female (×4). After Howard." /></a>
+<span class="caption">132. Anopheles crucians. Female (×4). After Howard.</span>
+</div>
+
+<p>Such was the condition in Philadelphia in 1793 and, as far as
+methods of control of the disease were concerned, there was practically
+no advance during the last century. The dominant theory
+was that yellow fever was spread by <i>fomites</i>, that is, exposed bedding,
+clothing, baggage, and the like. As late as 1898 a bulletin of the
+United States Marine Hospital Service stated:<span class="pagenum"><a name="Page_200" id="Page_200">[Pg 200]</a></span></p>
+
+<p>"While yellow fever is a communicable disease, it is not contagious
+in the ordinary acceptance of the term, but is spread by the
+infection of places and articles of bedding, clothing, and furniture."</p>
+
+<p>Based upon this theory, houses, baggage, freight, even mail,
+were disinfected, and the most rigid quarantine regulations were
+enforced. The hardships to which people of the stricken regions
+were subjected and the financial losses are incalculable. And withal,
+the only efficient check upon the disease seemed to be the heavy frosts.
+It was found that for some reason, the epidemic abated with cold
+weather,&mdash;a measure beyond human control.</p>
+
+<div class="figcenter" style="width: 500px;">
+<a href="images/f133-full.png"><img src="images/f133.png" width="500" height="518" alt="133. Culex sollicitans. Female (×4). After Howard." title="133. Culex sollicitans. Female (×4). After Howard." /></a>
+<span class="caption">133. Culex sollicitans. Female (×4). After Howard.</span>
+</div>
+
+<p>It is not strange that among the multitude of theories advanced to
+explain the cause and method of dissemination of the disease there
+should be suggestions that yellow fever was transmitted by the
+mosquito. We have seen that Beauperthuy (1855) clearly urged
+this theory.</p>
+
+<p>More detailed, and of the greatest influence in the final solution
+of the problem were the arguments of Dr. Cárlos Finlay, of Havana.
+In 1881, in a paper presented before the "Real Academia de Ciencias
+Médicas, Físicas y Naturales de la Habana," he said:<span class="pagenum"><a name="Page_201" id="Page_201">[Pg 201]</a></span></p>
+
+<p>"I feel convinced that any theory which attributes the origin and
+the propagation of yellow fever to atmospheric influences, to miasmatic
+or meteorological conditions, to filth, or to the neglect of general
+hygienic precautions, must be considered as utterly indefensible."</p>
+
+<p>He postulated the existence of a material transportable substance
+causing yellow fever,&mdash;"something tangible which requires to be
+conveyed from the sick to the healthy before the disease can be
+propagated" and after discussing the peculiarities of the spread of
+the disease and the influence of meteorological conditions, he decides
+that the carriers of the disease must be sought among insects. He
+continues:</p>
+
+<p>"On the other hand, the fact of yellow fever being characterized
+both clinically and (according to recent findings) histologically, by
+lesions of the blood vessels and by alterations of the physical and
+chemical conditions of the blood, suggested that the insect which
+should convey the infectious particles from the patient to the healthy
+should be looked for among those which drive their sting into blood
+vessels in order to suck human blood. Finally, by reason of other
+considerations which need not be stated here, I came to think that
+the mosquito might be the transmitter of yellow fever."</p>
+
+<p>"Assimilating the disease to small-pox and to vaccination, it
+occurred to me that in order to inoculate yellow fever it would be
+necessary to pick out the inoculable material from within the blood
+vessels of a yellow fever patient and to carry it likewise into the
+interior of a blood vessel of a person who was to be inoculated. All
+of which conditions the mosquito satisfies most admirably through
+its bite."</p>
+
+<p>In the course of his study of the problem, Finlay made detailed
+studies of the life history and habits of the common mosquitoes at
+Havana, and arrived at the conclusion that the carrier of the yellow
+fever was the <i>Culex mosquito</i> or <i>Aëdes calopus</i>, as it is now known.
+With this species he undertook direct experimental tests, and believed
+that he succeeded in transmitting the disease by the bite of
+infected mosquitoes in three cases. Unfortunately, possibility
+of other exposure was not absolutely excluded, and the experiments
+attracted little attention.</p>
+
+<p>Throughout the next twenty years Finlay continued his work on
+yellow fever, modifying his original theory somewhat as time went on.
+Among his later suggestions was that in the light of Smith's work
+on Texas fever, his theory must be "somewhat modified so as to<span class="pagenum"><a name="Page_202" id="Page_202">[Pg 202]</a></span>
+include the important circumstance that the faculty of transmitting
+the yellow fever germ need not be limited to the parent insect,
+directly contaminated by stinging a yellow fever patient (or perhaps
+by contact with or feeding from his discharges), but may be
+likewise inherited by the next generation of mosquitoes issued from
+the contaminated parent." He believed that the bite of a single
+mosquito produced a light attack of the disease and was thus effective
+in immunizing the patient. Throughout the period, many
+apparently successful attempts to transmit the disease by mosquitoes
+were made. In the light of present day knowledge we must
+regard these as defective not only because possibility of other infection
+was not absolutely excluded but because no account was taken
+of the incubation period within the body of the mosquito.</p>
+
+<p>In 1900, while the American army was stationed in Cuba there
+occurred an epidemic of yellow fever and an army medical board was
+appointed for "the purpose of pursuing scientific investigations with
+reference to the acute infectious diseases prevalent on the island."
+This was headed by Walter Reed and associated with him were James
+Carroll, Jesse W. Lazear and Aristides Agramonte, the latter a Cuban
+immune. For a detailed summary of this work the lay reader cannot
+do better than read Dr. Kelly's fascinating biography "Walter
+Reed and Yellow Fever."</p>
+
+<p>Arriving at the army barracks near Havana the Commission first
+took up the study of <i>Bacillus icteroides</i>, the organism which Sanarelli,
+an Italian physician, had declared the causative agent in yellow fever.
+They were unable to isolate this bacillus either from the blood during
+life or from the blood and organs of cadavers and therefore turned
+their attention to Finlay's theory of the propagation of yellow fever
+by means of the mosquito. In this work they had the unselfish
+and enthusiastic support of Dr. Finlay himself, who not only consulted
+with them and placed his publications at their disposal, but furnished
+eggs from which their experimental mosquitoes were obtained.
+Inoculations of eleven non-immunes through the bite of infected
+mosquitoes were made, and of these, two gave positive results. The
+first of the two was Dr. Carroll who allowed himself to be bitten
+by a mosquito which had been caused to feed upon four cases of
+yellow fever, two of them severe and two mild. The first patient
+had been bitten twelve days before.</p>
+
+<p>Three days after being bitten, Dr. Carroll came down with a
+typical case of yellow fever. So severe was the attack that for three<span class="pagenum"><a name="Page_203" id="Page_203">[Pg 203]</a></span>
+days his life hung in the balance. During his convalescence an
+incident occurred which showed how the theory of mosquito transmission
+of the disease was generally regarded. We quote from Dr.
+Kelly: "One of his nurses who came from Tennessee had had considerable
+experience with yellow fever, having indeed, lost her husband
+and several children from it. One day early in his illness Dr.
+Carroll mentioned to her that he had contracted the disease through
+the bite of a mosquito, and noticed that she looked surprised. Some
+time later, when well enough to look over the daily records of his
+condition, he found this entry: 'Says he got his illness through the
+bite of a mosquito,&mdash;delirious'."</p>
+
+<p>The second case was that of an American who was bitten by four
+mosquitoes, two of which had bitten severe (fatal) cases of yellow
+fever twelve days previously, one of which had bitten a severe case
+(second day) sixteen days before and one which had bitten a severe
+case eight days before. Five days later, the subject developed a well
+pronounced but mild case of the disease.</p>
+
+<p>In the meantime, another member of the Commission, Dr. Lazear,
+was accidentally bitten by a mosquito while collecting blood from
+yellow fever patients. Five days later he contracted a typical case
+which resulted fatally.</p>
+
+<p>So clear was the evidence from these preliminary experiments
+that the commission felt warranted in announcing, October 27, 1900,
+that, "The mosquito serves as the intermediate host for the parasite
+of yellow fever, and it is highly probable that the disease is only
+propagated through the bite of this insect."</p>
+
+<p>In order to extend the experimental evidence under conditions
+which could leave no possibility of infection from other sources, a
+special experimental sanitary station, named in honor of the deceased
+member of the Commission, was established in an open field near
+the town of Quemados, Cuba. Here there were constructed two small
+buildings known respectively as the "infected clothing building"
+and the "infected mosquito building."</p>
+
+<p>The infected clothing building, 14 × 20 feet in size, was purposely
+so constructed as to exclude anything like efficient ventilation, but
+was thoroughly screened to prevent the entrance of mosquitoes.
+Into this building were brought sheets, pillow-slips, blankets, etc.,
+contaminated by contact with cases of yellow fever and their discharges,&mdash;many
+of them purposely soiled with a liberal quantity of
+black vomit, urine, and fecal matter from patients sick with yellow<span class="pagenum"><a name="Page_204" id="Page_204">[Pg 204]</a></span>
+fever. Nothing could better serve as the fomites which were supposed
+to convey the dread disease.</p>
+
+<p>Three non-immunes unpacked these articles, giving each a
+thorough handling and shaking in order to disseminate through the
+air of the room the specific agent of the disease. They were then
+used in making up the beds which the volunteers occupied each night
+for a period of twenty days. The experiment was repeated three
+times, volunteers even sleeping in the soiled garments of yellow fever
+victims but in not a single case was there the slightest symptom of
+disease. The theory of the spread of yellow fever by fomites was
+completely demolished.</p>
+
+<p>The infected mosquito building, equal in size to its companion,
+was the antithesis as far as other features were concerned. It was
+so constructed as to give the best possible ventilation, and bedding
+which was brought into it was thoroughly sterilized. Like the
+infected clothing building it was carefully screened, but in this case
+it was in order to keep mosquitoes in it as well as to prevent entrance
+of others. Through the middle of the room ran a mosquito-proof
+screen.</p>
+
+<p>On December 5, 1900, a non-immune volunteer who had been in
+the quarantine camp for fifteen days and had had no other possible
+exposure, allowed himself to be bitten by five mosquitoes which had
+fed on yellow fever patients fifteen or more days previously. The
+results were fully confirmatory of the earlier experiments of the
+Commission&mdash;at the end of three days, nine and a half hours, the
+subject came down with a well marked case of yellow fever.</p>
+
+<p>In all, ten cases of experimental yellow fever, caused by the bite
+of infected mosquitoes were developed in Camp Lazear. Throughout
+the period of the disease, other non-immunes slept in the little
+building, separated from the patient only by the mosquito-proof
+screen, but in no circumstances did they suffer any ill effects.</p>
+
+<p>It was found that a yellow fever patient was capable of infecting
+mosquitoes only during the first three or four days after coming
+down with the disease. Moreover, after the mosquito has bitten
+such a patient, a period of at least twelve days must elapse before
+the insect is capable of transmitting the disease.</p>
+
+<p>Once the organism has undergone its twelve day development,
+the mosquito may remain infective for weeks. In experiments of
+the Commission, two of the mosquitoes transmitted the disease to a
+volunteer fifty-seven days after their contamination. No other<span class="pagenum"><a name="Page_205" id="Page_205">[Pg 205]</a></span>
+volunteers presenting themselves, one of these mosquitoes died the
+sixty-ninth and one the seventy-first day after their original contamination,
+without it being determined whether they were still
+capable of transmitting the disease.</p>
+
+<p>So carefully carried out was this work and so conclusive were the
+results that Dr. Reed was justified in writing:</p>
+
+<p>"Six months ago, when we landed on this island, absolutely nothing
+was known concerning the propagation and spread of yellow
+fever&mdash;it was all an unfathomable mystery&mdash;but today the curtain
+has been drawn&mdash;its mode of propagation is established and we know
+that a case minus mosquitoes is no more dangerous than one of
+chills and fever."</p>
+
+<p>The conclusions of the Commission were fully substantiated by
+numerous workers, notably Dr. Guiteras of the Havana Board of
+Health, who had taken a lively interest in the work and whose
+results were made known in 1901, and by the Brazilian and French
+Commission at Sao Paulo, Brazil, in 1903.</p>
+
+<p>Throughout the work of the Army Commission and down to the
+present time many fruitless efforts have been made to discover the
+specific organism of yellow fever. It was clearly established that
+the claims of Sanarelli for <i>Bacillus icteroides</i> were without foundation.
+It was found, too, that whatever the infective agent might
+be it was capable of passing through a Berkefeld filter and thus belongs
+to the puzzling group of "filterable viruses." It was further
+found that the virus was destroyed by heating up to 55° C for ten
+minutes. It is generally believed that the organism is a Protozoan.</p>
+
+<p>The question of the hereditary transmission of the yellow fever
+organism within the mosquito was left unsettled by the Army Commission,
+though, as we have seen, it was raised by Finlay. Marchoux
+and Simond, of the French Commission devoted much attention to
+this phase of the problem and basing their conclusions on one apparently
+positive case, they decided that the disease could be transmitted
+through the egg of an infected <i>Aëdes calopus</i> to the second
+generation and thence to man. The conclusion, which is of very
+great importance in the control of yellow fever, has not been verified
+by other workers.</p>
+
+<p>Once clearly established that yellow fever was transmitted solely
+by mosquitoes, the question of the characteristics, habits, and geographical
+distribution of the insect carrier became of vital importance.<span class="pagenum"><a name="Page_206" id="Page_206">[Pg 206]</a></span></p>
+
+<p><i>Aëdes calopus</i>, more commonly known as <i>Stegomyia fasciata</i> or
+<i>Stegomyia calopus</i> (<a href="#Fig_134">fig.&nbsp;134</a>) is a moderate sized, rather strikingly
+marked mosquito. The general color is dark-brown or reddish-brown,
+but the thorax has a conspicuous broad, silvery-white curved
+line on each side, with two parallel median silvery lines. Between
+the latter there is a
+slender, broken line.
+The whole gives a lyre-shaped
+pattern to the
+thorax. The abdomen
+is dark with silvery-white
+basal bands and
+silvery white spots on
+each side of the abdominal
+segments.
+Legs black with rings
+of pure white at the
+base of the segments.</p>
+
+<p>Size of the female
+3.3 to 5 mm.; male 3
+to 4.5 mm.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_134" id="Fig_134"></a>
+<a href="images/f134-full.png"><img src="images/f134.png" width="500" height="702" alt="134. The yellow fever mosquito (Aëdes calopus). (×7).
+After Howard." title="134. The yellow fever mosquito (Aëdes calopus). (×7).
+After Howard." /></a>
+<span class="caption">134. The yellow fever mosquito (Aëdes calopus). (×7).
+After Howard.</span>
+</div>
+
+<p>It is preeminently
+a domesticated species,
+being found almost
+exclusively about the
+habitation of man.
+"Its long association
+with man is shown by
+many of its habits. It
+approaches stealthily
+from behind. It retreats
+upon the slightest
+alarm. The ankles and, when one is sitting at a table or desk,
+the underside of the hands and wrists are favorable points of attack.
+It attacks silently, whereas other mosquitoes have a piping or humming
+note. The warning sound has doubtless been suppressed in
+the evolutionary process of its adaptation to man. It is extremely
+wary. It hides whenever it can, concealing itself in garments,
+working into the pockets, and under the lapels of coats, and crawling
+up under the clothes to bite the legs. In houses, it will hide<span class="pagenum"><a name="Page_207" id="Page_207">[Pg 207]</a></span>
+in dark corners, under picture moldings and behind the heads of
+old-fashioned bedsteads. It will enter closets and hide in the folds
+of garments."&mdash;Howard.</p>
+
+<p>It was claimed by the French Commission, and subsequently
+often stated in discussions of the relation of the mosquito to yellow
+fever that the mature <i>Aëdes calopus</i> will bite only at night. If this
+were true it would be of the greatest importance in measures to
+avoid the disease. Unfortunately, the claim was illy founded and
+numerous workers have clearly established that the exact converse
+is more nearly true, this mosquito being pre-eminently a day species,
+feeding most actively in early morning,
+about sunrise, and late in the afternoon.
+On cloudy days it attacks at any time
+during the day. Thus there is peril in
+the doctrine that infected regions may
+be visited with perfect safety during
+the daytime and that measures to
+avoid the mosquito attack need be
+taken only at night.</p>
+
+<div class="figright" style="width: 350px;">
+<a href="images/f135a-full.png"><img src="images/f135a.png" width="350" height="430" alt="135a. Aëdes calopus. Pupa.
+After Howard." title="135a. Aëdes calopus. Pupa.
+After Howard." /></a>
+<span class="caption">135<i>a</i>. Aëdes calopus. Pupa.
+After Howard.</span>
+</div>
+
+<p>Dr. Finlay maintained that the
+adult, even when starved, would not
+bite when the temperature was below
+23°&nbsp;C, but subsequent studies have
+shown that this statement needs modification.
+The French Commission,
+working at Rio de Janeiro, found that <i>Aëdes calopus</i> would bite
+regularly at temperatures between 22° and 25° and that the optimum
+temperature was between 27° and 30° C, but their experiments led
+them to believe that it would bite in nature at a temperature as
+low as 17° C.</p>
+
+<p>The yellow fever mosquito breeds in cisterns, water barrels,
+pitchers and in the various water receptacles about the house. In
+our own Southern States it very commonly breeds in the above-ground
+cisterns which are in general use. Often the larvæ (<a href="#Fig_135b">fig.&nbsp;135b</a>)
+are found in flower vases, or even in the little cups of water which
+are placed under the legs of tables to prevent their being overrun by
+ants. They have been repeatedly found breeding in the holy water
+font in churches. In short, they breed in any collection of water in
+close proximity to the dwellings or gathering places of man.<span class="pagenum"><a name="Page_208" id="Page_208">[Pg 208]</a></span></p>
+
+<p>The life cycle under favorable conditions is completed in from
+twelve to fifteen days. These figures are of course very dependent
+upon the temperature. The Army Commission in Cuba found that
+the cycle might be completed in as brief a period as nine and a half
+days. Under less favorable conditions it may be greatly lengthened.</p>
+
+<p>The adults are long lived. We have
+seen that during the experimental work
+in Cuba specimens were kept in captivity
+for sixty-nine and seventy-one
+days, respectively, and that they were
+proved to retain their infectivity for at
+least fifty-seven days. Dr. Guiteras
+subsequently kept an infected adult for
+one hundred and fifty-four days.</p>
+
+<p>Low temperatures have a very great
+effect not only on development, but on
+the activity and even life of the adults.
+Long before the method of transmission
+of yellow fever was discovered it was well
+known that the epidemics were brought
+to a close by heavy frosts, and it is now
+known that this is due to the killing of
+the mosquitoes which alone could spread
+the disease.</p>
+
+<div class="figleft" style="width: 300px;"><a name="Fig_135b" id="Fig_135b"></a>
+<a href="images/f135b-full.png"><img src="images/f135b.png" width="300" height="695" alt="135b. Aëdes calopus; larva. (×7).
+After Howard." title="135b. Aëdes calopus; larva. (×7).
+After Howard." /></a>
+<span class="caption">135<i>b</i>. Aëdes calopus; larva. (×7).
+After Howard.</span>
+</div>
+
+<p><i>Aëdes calopus</i> has a very wide distribution
+since, as Howard says, being a
+domestic mosquito, having a fairly long
+life in the adult stage, and having the
+custom of hiding itself in the most ingenious
+ways, it is particularly subject to carriage
+for long distances on board vessels,
+in railway trains, even packed in baggage. In general, its permanent
+distribution is from 40 degrees north latitude to 40 degrees south
+latitude (Brumpt), in a belt extending around the world. In the
+United States it breeds in most of our Southern States.</p>
+
+<p>Thus, as in the case of malaria, there are many places where the
+insect carrier is abundant but where yellow fever does not occur.
+Such, for instance, are Hawaii, Australia and Asia. An outbreak may
+occur at any time that a patient suffering from the disease is allowed
+to enter and become a source of infection for the mosquitoes. In<span class="pagenum"><a name="Page_209" id="Page_209">[Pg 209]</a></span>
+this connection various writers have called attention to the menace
+from the Panama Canal. When it is completed, it will allow of
+direct passage from regions where yellow fever is endemic and this
+will greatly increase the possibility of its introduction into these places
+where it is now unknown. The result, with a wholly non-immune
+population, would be appalling.</p>
+
+<p>On the other hand, there are places wholly outside of the normal
+range of <i>Aëdes calopus</i> where the disease has raged. Such are New
+York, Boston, and even Philadelphia, which have suffered notable
+epidemics. These outbreaks have been due to the introduction of
+infected mosquitoes during the heat of summer, when they have not
+only conveyed the disease but have found conditions favorable
+for their multiplication. Or, uninfected mosquitoes have been thus
+accidentally brought in and developed in large numbers, needing
+then only the accidental introduction of cases of the disease to start
+an epidemic.</p>
+
+<p>Methods of control of various diseases have been revolutionized
+by the discovery that they were insect-borne, but in no other case
+has the change been as radical or the results as spectacular as in the
+case of yellow fever. The "shot-gun quarantine," the sufferings and
+horrors, the hopelessness of fighting absolutely blindly have given
+way to an efficient, clear-cut method of control, based upon the knowledge
+that the disease is carried from man to man solely by the mosquito,
+<i>Aëdes calopus</i>. The lines of defense and offense are essentially
+as follows:</p>
+
+<p>In the first place, when a case of yellow fever occurs, stringent
+precautions must be adopted to prevent the infection of mosquitoes
+and the escape of any already infected. This means that the patient
+must be removed to a mosquito-proof room, or ward beyond reach of
+the insects, and that the infected room must be thoroughly fumigated
+at once, to kill the mosquitoes hiding within it. All cracks
+and openings should be closed with strips of paper and fumigation
+with burning sulphur or pyrethrum carefully carried out.</p>
+
+<p>It should be remembered that if the first case noted is that of a
+resident rather than imported, it means that the mosquito carriers
+became infected more than two weeks before the case was diagnosed,
+for as we have seen, the germ must undergo a twelve-day period of
+development within its insect host. Therefore a careful search must
+be made for mild cases which, though unrecognized, may serve as
+foci for the spread of the disease.<span class="pagenum"><a name="Page_210" id="Page_210">[Pg 210]</a></span></p>
+
+<p>In face of a threatened epidemic one of the most essential measures
+is to educate the citizens and to gain their complete coöperation in
+the fight along modern lines. This may be done through the schools,
+the pulpit, places of amusement, newspapers and even bulletin
+boards.</p>
+
+<p>Emphasis should be placed on the necessity of both non-immunes
+and immunes using mosquito curtains, and in all possible ways
+avoiding exposure to the mosquitoes.</p>
+
+<p>Then the backbone of the fight must be the anti-mosquito measures.
+In general, these involve screening and fumigating against
+adults, and control of water supply, oiling, and drainage against the
+larvæ. The region involved must be districted and a thorough survey
+undertaken to locate breeding places, which must, if possible,
+be eradicated. If they are necessary for water supplies, such as
+casks, or cisterns, they should be carefully screened to prevent
+access of egg-laying adults.</p>
+
+<p>The practical results of anti-mosquito measures in the fight
+against yellow fever are well illustrated by the classic examples of
+the work in Havana, immediately following the discoveries of the
+Army Commission and by the stamping out of the New Orleans
+epidemic in 1905.</p>
+
+<p>The opportunities for an immediate practical application of the
+theories of the Army Commission in Havana were ideal. The city
+had always been a hotbed of yellow fever and was the principal
+source from which the disease was introduced year after year into
+our Southern States. It was under martial law and with a military
+governor who was himself a physician and thoroughly in sympathy
+with the views of the Commission, the rigid enforcement of the
+necessary regulations was possible. The story of the first campaign
+has been often told, but nowhere more clearly than in Dr. Reed's
+own account, published in the <i>Journal of Hygiene</i> for 1902.</p>
+
+<p>Closer home was the demonstration of the efficacy of these
+measures in controlling the yellow fever outbreak in New Orleans
+in 1905. During the spring and early summer of the year the disease
+had, unperceived, gained a firm foothold in that city and when, in
+early July the local Board of Health took cognizance of its existence,
+it was estimated that there had been in the neighborhood of one
+hundred cases.</p>
+
+<p>Conditions were not as favorable as they had been under martial
+law in Havana for carrying on a rigid fight along anti-mosquito lines.<span class="pagenum"><a name="Page_211" id="Page_211">[Pg 211]</a></span>
+The densely populated city was unprepared, the public had to be
+educated, and an efficient organization built up. The local authorities
+actively began a general fight against the mosquito but in spite
+of their best efforts the disease continued to spread. It was recognized
+that more rigid organization was needed and on August 12th
+the United States Public Health and Marine Hospital Service was
+put in absolute charge of the fight. Up to this time there had been
+one hundred and forty-two deaths from a total of nine hundred and
+thirteen cases and all of the conditions seemed to threaten an outbreak
+to exceed the memorable one of 1878 when, as we have seen
+there were four thousand and forty-six deaths.</p>
+
+<p>With the hearty coöperation of the citizens,&mdash;physicians and
+laymen alike,&mdash;the fight was waged and long before frost or any near
+approach thereto the disease was stamped out,&mdash;a thing unheard of
+in previous epidemics. The total loss of life was four hundred and
+sixty&mdash;about 11 per cent as great as that from the comparable epidemic
+of 1878. If the disease had been promptly recognized and
+combated with the energy which marked the fight later in the summer,
+the outbreak would have made little headway and the great
+proportion of these lives would have been saved.<span class="pagenum"><a name="Page_212" id="Page_212">[Pg 212]</a></span></p>
+
+
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="CHAPTER_IX" id="CHAPTER_IX"></a>CHAPTER IX</h2>
+
+<h2><span title="insert &quot;continued&quot;">ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA</span></h2>
+
+
+<h3><span class="smcap"><a name="Insects_and_Trypanosomiases" id="Insects_and_Trypanosomiases"></a>Insects and Trypanosomiases</span></h3>
+
+<p>By trypanosomiasis is meant a condition of animal parasitism,
+common to man and the lower animals, in which trypanosomes,
+peculiar flagellate protozoa, infest the blood. Depending upon the
+species, they may be harmless, producing no appreciable ill-effect,
+or pathogenic, giving rise to conditions of disease. A number of
+these are known to be transferred by insects.</p>
+
+<p>In order that we may
+consider more fully the
+developmental stage of
+these parasites within
+their insect host, it is
+necessary that we describe
+briefly the structure
+of the blood-inhabiting
+stage.</p>
+
+<div class="figcenter" style="width: 360px;"><a name="Fig_136" id="Fig_136"></a>
+<a href="images/f136-full.png"><img src="images/f136.png" width="360" height="290" alt="136. Trypanosome brucei. After Bruce." title="136. Trypanosome brucei. After Bruce." /></a>
+<span class="caption">136. Trypanosoma brucei. After Bruce.</span>
+</div>
+
+<p>The trypanosomes are
+elongated, usually pointed,
+flagellated protozoa
+(<a href="#Fig_136">fig.&nbsp;136</a>) in which the
+single flagellum, bent
+under the body, forms the
+outer limit of a delicate undulating membrane. It arises near
+one end of the organism from a minute centrosome-like body
+which is known as the blepheroplast, and at the opposite end extends
+for a greater or less distance as a free flagellum. Enclosing, or
+close beside the blepheroplast is the small kinetonucleus. The
+principal nucleus, round or oval in form, is situated near the center
+of the body. Asexual reproductions occurs in this stage, by longitudinal
+fission, the nucleus and the blepheroplast dividing independently
+of one another. From the blepheroplast of one of the daughter
+cells a new flagellum is formed.</p>
+
+<p>Among the pathogenic species are to be found the causative
+organisms of some of the most serious diseases of domestic animals
+and even of man. It is probable that these pathogenic species secrete<span class="pagenum"><a name="Page_213" id="Page_213">[Pg 213]</a></span>
+a specific poison. The majority of them are tropical in distribution.</p>
+
+<p>Though we are concerned especially with the species which infest
+man, we shall first consider two of the trypanosomes of lower animals,
+known long before any of those of man had been found.</p>
+
+
+<p><a name="Fleas_and_Lice_as_Carriers_of_Trypanosoma_lewisi" id="Fleas_and_Lice_as_Carriers_of_Trypanosoma_lewisi"></a><b>Fleas and Lice as Carriers of Trypanosoma lewisi.</b>&mdash;<i>Trypanosoma
+lewisi</i>, the first mammalian trypanosome known, is to be found in the
+blood of wild rats. Like its host, it appears to be cosmopolitan in
+distribution, having been reported from several localities in the
+United States, Brazil, Argentine, England, Germany, France, Italy,
+Russia, Asia and Africa.</p>
+
+<p>This species is usually regarded as non-pathogenic, but in experimental
+work, especially with white rats, heavy infestations often
+result fatally, and naturally infested specimens sometimes show
+evidence of injury. Rats which have been infested exhibit at least
+temporary immunity against new infection.</p>
+
+<p><i>Trypanosoma lewisi</i> is transmitted from rat to rat by fleas and
+by lice. Rabinowitsch and Kempner (1899) first found that healthy
+rats which were kept with infested rats, showed trypanosomes in
+their blood after about two weeks. They found the trypanosomes
+in the alimentary canal of fleas which had fed on the diseased rats.
+On teasing such fleas in physiological salt solution and inoculating
+them into fresh rats they were able to produce the infection. Finally,
+they showed that the fleas which had fed upon infested rats were
+able to carry the parasites to healthy rats. Corresponding experiments
+with lice were not successful. Prowazek (1905) found in the
+rat louse (<i>Hæmatopinus spinulosus</i>) organisms which he regarded
+as developmental stages of the <i>Trypanosoma lewisi</i>. He believed
+that the sexual cycle was undergone in this insect.</p>
+
+<p>Nuttall (1908) readily transmitted the trypanosomes through the
+agency of fleas, (<i>Ceratophyllus fasciatus</i> and <i>Ctenopthalmus agyrtes</i>).
+He believes that these insects are probably the chief transmitters
+of the parasite. He was also able to transmit it from diseased to
+healthy rats through the agency of the rat louse. He was unable
+to trace any developmental stages in the louse and inclined to the
+opinion that Prowazek was deceived by the presence of extraneous
+flagellates such as are known to exist in a number of blood-sucking
+arthropods.</p>
+
+<p>Nuttall concludes that since three distinct kinds of blood-sucking
+insects are capable of transmitting <i>Trypanosoma lewisi</i> it appears<span class="pagenum"><a name="Page_214" id="Page_214">[Pg 214]</a></span>
+doubtful that this flagellate is a parasite of the invertebrate "host"
+in the sense claimed by Prowazek and other investigators.</p>
+
+
+<p><a name="Tsetse-flies_and_Nagana" id="Tsetse-flies_and_Nagana"></a><b>Tsetse-flies and Nagana</b>&mdash;One of the greatest factors in retarding
+the development of certain regions of Africa has been the presence
+of a small fly, little larger than the common house-fly. This is the
+tsetse-fly, <i>Glossina morsitans</i> (<a href="#Fig_165">fig.&nbsp;165</a>) renowned on account of the
+supposed virulence of its bite for cattle, horses and other domestic
+mammals.</p>
+
+<p>The technical characteristics of the tsetse-flies, or Glossinas, and
+their several species, will be found in a later chapter. We need
+emphasize only that they are blood-sucking Muscidæ and that,
+unlike the mosquitoes, the sexes resemble each other closely in structure
+of the mouth-parts, and in feeding habits.</p>
+
+<p>In 1894, Colonel David Bruce discovered that the fly was not in
+itself poisonous but that the deadly effect of its bite was due to the
+fact that it transmitted a highly pathogenic blood parasite, <i>Trypanosoma
+brucei</i>. This trypanosome Bruce had discovered in the blood
+of South African cattle suffering from a highly fatal disease known as
+"nagana". On inoculating the blood of infected cattle into horses
+and dogs he produced the disease and found the blood teeming with
+the causative organism. In the course of his work he established
+beyond question that the "nagana" and the tsetse-fly disease were
+identical.</p>
+
+<p>Tsetse-flies of the species <i>Glossina morsitans</i>, which fed upon
+diseased animals, were found capable of giving rise to the disease
+in healthy animals up to forty-eight hours after feeding. Wild
+tsetse-flies taken from an infected region to a region where they did
+not normally occur were able to transmit the disease to healthy
+animals. It was found that many of the wild animals in the tsetse-fly
+regions harbored <i>Trypanosoma brucei</i> in their blood, though they
+showed no evidence of disease. As in the case of natives of malarial
+districts, these animals acted as reservoirs of the parasite. Non-immune
+animals subjected to the attacks of the insect carrier, quickly
+succumbed to the disease.</p>
+
+<p>A question of prime importance is as to whether the insect serves
+as an essential host of the pathogenic protozoan or whether it is a
+mere mechanical carrier. Bruce inclined to the latter view. He was
+unable to find living trypanosomes in the intestines or excrements
+of the fly or to produce the disease on the many occasions when he<span class="pagenum"><a name="Page_215" id="Page_215">[Pg 215]</a></span>
+injected the excrement into healthy animals. Moreover, he had
+found that the experimental flies were infective only during the first
+forty-eight hours and that if wild flies were taken from the infected
+region, "kept without food for three days and then fed on a healthy
+dog, they never gave rise to the disease."</p>
+
+<p>Koch had early described what he regarded as sexual forms from
+the intestine of the fly but it remained for Kleine (1909) to experimentally
+demonstrate that a part of the life cycle of the parasite
+was undergone in the fly. Working with <i>Glossina palpalis</i>, he found
+that for a period of ten days or longer after feeding on an animal
+suffering from nagana it was non-infective, but that then it became
+infective and was able to transmit the disease for weeks thereafter.
+He discovered and described developmental stages of the parasite
+within the intestine of the insect. In other words, the tsetse-fly
+(in nature, <i>Glossina morsitans</i>), serves as an essential host, within
+which an important part of the life cycle of the parasite is undergone.
+These conclusions were quickly verified by Bruce and numerous
+other workers and are no longer open to question. Klein and Taute
+are even inclined to think that mechanical transmission plays practically
+no rôle in nature, unless the fly is interrupted while feeding
+and passes immediately to a new animal.</p>
+
+
+<p><a name="Tsetse-flies_and_Sleeping_Sickness_of_Man" id="Tsetse-flies_and_Sleeping_Sickness_of_Man"></a><b>Tsetse-flies and Sleeping Sickness of Man</b>&mdash;About the beginning
+of the present century a hitherto little known disease of man began
+to attract great attention on account of its ravages in Uganda and
+the region of Victoria Nyanza in South Africa. It was slow, insiduous
+and absolutely fatal, characterized in its later stages by dullness,
+apathy, and finally absolute lethargy all day long, symptoms which
+gave it the name of "sleeping sickness."</p>
+
+<p>It was soon found that the disease was not a new one but that it
+had been known for over a hundred years on the west coast of Africa.
+Its introduction into Central and East Africa and its rapid spread
+have been attributed primarily to the development of the country,
+the formation of new trade routes and the free mingling of native
+tribes formerly isolated. It is estimated that in the first ten years
+of the present century there were approximately two hundred
+thousand deaths from the disease in the Uganda protectorate. In
+the British province Bugosa, on the Victoria Nyanza there were
+thirty thousand deaths in the period from 1902-1905.<span class="pagenum"><a name="Page_216" id="Page_216">[Pg 216]</a></span></p>
+
+<p>While the disease is peculiarly African there are a number of
+instances of its accidental introduction into temperate regions.
+Slaves suffering from it were occasionally brought to America in
+the early part of the last century and cases have sometimes been
+imported into England. In none of the cases did the disease gain a
+foothold or spread at all to other individuals.</p>
+
+<p>In 1902 Dutton described a trypanosome, <i>T. gambiense</i>, which he
+and Forde had found the year before in the blood of a patient suffering
+from a peculiar type of fever in Gambia. In 1902-1903 Castellani
+found the same parasite in the cerebro-spinal fluid of sleeping-sickness
+patients and definitely reported it as the causative organism
+of the disease. His work soon found abundant confirmation, and
+it was discovered that the sleeping sickness was but the ultimate
+phase of the fever discovered by Dutton and Forde.</p>
+
+<p>When Castellani made known his discovery of the trypanosome
+of sleeping sickness, Brumpt, in France, and Sambon, in England,
+independently advanced the theory that the disease was transmitted
+by the tsetse-fly, <i>Glossina palpalis</i>. This theory was based upon the
+geographical distribution and epidemiology of the disease. Since
+then it has been abundantly verified by experimental evidence.</p>
+
+<p>Fortunately for the elucidation of problems relating to the methods
+of transfer of sleeping sickness, <i>Trypanosoma gambiense</i> is pathogenic
+for many species of animals. In monkeys it produces symptoms
+very similar to those caused in man. Bruce early showed that
+<i>Glossina palpalis</i> "fed on healthy monkeys eight, twelve, twenty-four
+and forty-eight hours after having fed on a native suffering from
+trypanosomiasis, invariably transmitted the disease. After three
+days the flies failed to transmit it." In his summary in Osler's
+Modern Medicine, he continues "But this is not the only proof that
+these flies can carry the infective agent. On the lake shore there
+was a large native population among whom we had found about
+one-third to be harboring trypanosomes in their blood. The tsetse-flies
+caught on this lake shore, brought to the laboratory in cages,
+and placed straightway on healthy monkeys, gave them the disease
+in every instance, and furnished a startling proof of the danger of
+loitering along the lake shore among those infected flies."</p>
+
+<p>As in the case of nagana, Bruce and most of the earlier investigators
+supposed the transmission of the sleeping sickness trypanosome
+by <i>Glossina palpalis</i> to be purely mechanical. The work of
+Kleine (1909) clearly showed that for <i>Trypanosoma gambiense</i> as<span class="pagenum"><a name="Page_217" id="Page_217">[Pg 217]</a></span>
+well as for <i>Trypanosoma brucei</i> the fly served as an essential host.
+Indeed, Kleine and many subsequent investigators are inclined to
+think that there is practically no mechanical transmission of trypanosomes
+from animal to animal by <i>Glossina</i> in nature, and that the
+many successful experiments of the earlier investigators were due
+to the fact that they used wild flies which already harbored the
+transformed parasite rather than directly inoculated it from the
+blood of the diseased experimental animals. While the criticism
+is applicable to some of the work, this extreme view is not fully
+justified by the evidence at hand.</p>
+
+<p>Kleine states (1912) that <i>Glossina palpalis</i> can no longer be
+regarded as the sole transmitter of sleeping sickness. Taute (1911)
+had shown that under experimental conditions <i>Glossina morsitans</i>
+was capable of transferring the disease and Kleine calls attention to
+the fact that in German East Africa, in the district of the Rovuma
+River, at least a dozen cases of the disease have occurred recently,
+though only <i>Glossina morsitans</i> exists in the district. It appears,
+however, that these cases are due to a different parasite, <i>Trypanosoma
+rhodesiense</i>. This species, found especially in north-east
+Rhodesia and in Nyassaland, is transferred by <i>Glossina morsitans</i>.</p>
+
+<p>Other workers maintain that the disease may be transmitted by
+various blood-sucking flies, or even bugs and lice which attack man.
+Fülleborn and Mayer (1907) have shown by conclusive experiments
+that <i>Aedes (Stegomyia) calopus</i> may transmit it from one
+animal to another if the two bites immediately succeed each other.</p>
+
+<p>It is not possible that insects other than the tsetse-flies (and only
+certain species of these), play an important rôle in the transmission
+of the disease, else it would be much more wide-spread. Sambon
+(1908) pointed out that the hypothesis that is spread by <i>Aedes
+calopus</i> is opposed by the fact that the disease never spread in the
+Antilles, though frequently imported there by West African slaves.
+The same observation would apply also to conditions in our own
+Southern States in the early part of the past century.</p>
+
+<p>Since <i>Glossina palpalis</i> acts as an essential host of the parasite
+and the chief, if not the only, transmitter, the fight against sleeping
+sickness, like that against malaria and yellow fever, becomes primarily
+a problem in economic entomology. The minutest detail
+of the life-history, biology, and habits of the fly, and of its parasites
+and other natural enemies becomes of importance in attempts to
+eradicate the disease. Here we can consider only the general features
+of the subject.<span class="pagenum"><a name="Page_218" id="Page_218">[Pg 218]</a></span></p>
+
+<p><i>Glossina palpalis</i> lives in limited areas, where the forest and undergrowth
+is dense, along the lake shore or river banks. According to
+Hodges, the natural range from shore is under thirty yards, though
+the distance to which the flies may follow man greatly exceed this.</p>
+
+<p>It is a day feeder, a fact which may be taken advantage of in
+avoiding exposure to its attacks. The young are brought forth alive
+and full-grown, one every nine or ten days. Without feeding, they
+enter the ground and under favorable conditions, complete their
+development in a month or more.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_137" id="Fig_137"></a>
+<a href="images/f137-full.png"><img src="images/f137.png" width="400" height="277" alt="137. Sleeping sickness concentration camp in German East Africa. Report of German
+Commission." title="137. Sleeping sickness concentration camp in German East Africa. Report of German
+Commission." /></a>
+<span class="caption">137. Sleeping sickness concentration camp in German East Africa. Report of German
+Commission.</span>
+</div>
+
+<p>Methods of control of the disease must look to the prevention
+of infection of the flies, and to their avoidance and destruction.
+Along the first line, much was hoped from temporary segregation
+of the sick in regions where the fly was not found. On the assumption
+that the flies acted as carriers only during the first two or three
+days, it was supposed that even the "fly belts" would become safe
+within a few days after the sick were removed. The problem was
+found to be a much more difficult one when it was learned that after
+a given brief period the fly again became infective and remained so
+for an indeterminate period. Nevertheless, isolation of the sick
+is one of the most important measures in preventing the spread of<span class="pagenum"><a name="Page_219" id="Page_219">[Pg 219]</a></span>
+the disease into new districts. Much, too, is being accomplished
+by moving native villages from the fly belts. (c.f. <a href="#Fig_137">fig.&nbsp;137</a>.)</p>
+
+<p>All measures to avoid the flies should be adopted. This means
+locating and avoiding the fly belts as far as possible, careful screening
+of houses, and protection of the body against bites.</p>
+
+<p>Clearing the jungle along the water courses for some yards beyond
+the natural range of the fly has proved a very important measure.
+Castellani recommends that the area be one hundred yards and
+around a village three hundred yards at least.</p>
+
+<p>Detailed studies of the parasites and the natural enemies of the
+tsetse-fly are being undertaken and may ultimately yield valuable
+results.</p>
+
+
+<p><a name="South_American_Trypanosomiasis" id="South_American_Trypanosomiasis"></a><b>South American Trypanosomiasis</b>&mdash;The tsetse-flies are distinctively
+African in distribution and until recently there were no trypanosomes
+known to infest man in America. In 1909 Dr. Chagas, of
+Rio de Janeiro described a new species, <i>Trypanosoma cruzi</i>, pathogenic
+to man.</p>
+
+<p><i>Trypanosoma cruzi</i> is the causative organism of a disease common
+in some regions of Brazil, where it is known as "opilacao." It is
+especially to be met with in children and is characterized by extreme
+anemia, wasting, and stunted development associated with fever,
+and enlargement of the thyroid glands. The disease is transmitted
+by the bites of several species of assassin-bugs, or Reduviidæ, notably
+by <i>Conorhinus megistus</i>. The evolution of the parasite within
+the bug has been studied especially by Chagas and by Brumpt.
+From the latter's text we take the following summary.</p>
+
+<p>The adult trypanosomes, ingested by a <i>Conorhinus megistus</i>, of
+any stage, first change into Crithidia-like forms and then those
+which remain in the stomach become ovoid and non-motile. Brumpt
+found these forms in immense numbers, in a <span title="for Cornohinus read Conorhinus"><a name="AC_12" id="AC_12"></a><i>Cornohinus</i></span> which had
+been infested fourteen months before. The forms which pass into
+the intestine quickly assume the <i>Crithidia</i> form and continue to
+develop rapidly under this form. Some weeks later they evolve
+into the trypanosome forms, pathogenic for man. They then pass
+out with the excrement of the bug and infect the vertebrate host
+as soon as they come in contact with any mucous layer (buccal,
+ocular or rectal). More rarely they enter through the epidermis.</p>
+
+<p>Brumpt showed that the development could take place in three
+species; bed-bugs (<i>Cimex lectularius</i>, <i>C.&nbsp;hemipterus</i>) and in the tick<span class="pagenum"><a name="Page_220" id="Page_220">[Pg 220]</a></span>
+<i>Ornithodoros moubata</i>. The evolution proceeds in the first two
+species of bed-bugs as rapidly as in Conorhinus, or even more rapidly,
+but they remain infective for a much shorter time and hence Brumpt
+considers that they play a much less important rôle in the spread of
+the disease.</p>
+
+<p><i>Conorhinus megistus</i>, like related forms in our Southern States,
+very commonly frequents houses and attacks man with avidity.
+Chagas states that the bites are painless and do not leave any traces.
+They are usually inflicted on the lips, or the cheeks and thus the
+buccal mucosa of a sleeper may be soiled by the dejections of the
+insect and the bite serving as a port of entry of the virus, remain
+unnoticed.</p>
+
+<p>The possibility of some of our North American Reduviidæ playing
+a similar rôle in the transmission of disease should not be overlooked.</p>
+
+
+<p><a name="Leishmanioses_and_Insects" id="Leishmanioses_and_Insects"></a><b>Leishmanioses and Insects</b>&mdash;Closely related to the trypanosomes
+is a group of intracellular parasites which have recently been grouped
+by Ross under the genus <i>Leishmania</i>. Five species are known to
+affect man. Three of these produce local skin infestations, but two
+of them, <i>Leishmania donovani</i> and <i>L. infantum</i>, produce serious and
+often fatal systemic diseases.</p>
+
+<p>The first of these, that produced by <i>L. donovani</i>, is an exceedingly
+virulent disease common in certain regions of India and China. It
+is commonly known as "Kala-azar," or "dum-dum" fever, and more
+technically as tropical leishmaniasis. Patton (1907) believes that
+the parasite is transmitted by the bed-bug <i>Cimex hemipterus</i>, and has
+described a developmental cycle similar to that which can be found
+in artificial cultures. On the other hand, Donovan was unable to
+confirm Patton's work and believes that the true intermediate host is
+a Reduviid bug, <i>Conorhinus rubrofasciatus</i>.</p>
+
+<p><i>Leishmania infantum</i> is the cause of the so-called infantile splenic
+leishmaniasis, occurring in northern Africa, Spain, Portugal, Italy,
+and possibly other parts of Europe. The parasite occurs habitually
+in the dog and is only accidentally transferred to children. Alvares
+and da Silva, in Portugal (according to Brumpt, 1913) have found
+that the excrement of a flea from a diseased dog contains flagellates,
+and they suggest that the infection may be transmitted by the accidental
+inoculation of this excrement by means of the proboscis of the
+flea, as has been thought to occur in the case of the plague. To this<span class="pagenum"><a name="Page_221" id="Page_221">[Pg 221]</a></span>
+Brumpt objects that they and other workers who thought to trace
+the development of <i>Leishmania infantum</i> were apparently misled by
+the presence of a harmless <i>Herpetomonas</i> which infests dog fleas in all
+countries, even where the leishmaniasis is unknown.</p>
+
+<p>Basile (1910 and 1911) however, carried on numerous experiments
+indicating that the disease was transferred from children to dogs
+and from dog to dog by the dog flea, and was able to find in the
+tissues of the insects forms perfectly identical with those found in
+children and in dogs suffering from leishmaniasis. He also found
+that <i>Pulex irritans</i> was capable of acting as the carrier.</p>
+
+<p>Of the cutaneous type of leishmaniasis, the best known is the so-called
+"Oriental sore," an ulcerative disease of the skin which is
+epidemic in many tropical and subtropical regions. The causative
+organism is <i>Leishmania tropica</i>, which occurs in the diseased tissues
+as bodies very similar to those found in the spleen in cases of
+Kala-azar. The disease is readily inoculable and there is no doubt
+that it may be transferred from the open sores to abraded surfaces of
+a healthy individual by house-flies. It is also believed by a number
+of investigators that it may be transferred and directly inoculated
+by various blood-sucking insects.</p>
+
+
+<h3><a name="Ticks_and_Diseases_of_Man_and_Animals" id="Ticks_and_Diseases_of_Man_and_Animals"></a><span class="smcap">Ticks and Diseases of Man and Animals</span></h3>
+
+<p>We have seen that the way to the discoveries of the relations of
+arthropods to disease was pointed out by the work of Leuckart and
+Melnikoff on the life cycle of <i>Dipylidium</i>, and of Fedtschenko and
+Manson on that of <i>Filaria</i>. They dealt with grosser forms, belonging
+to well-recognized parasitic groups.</p>
+
+<p>This was long before the rôle of any insect as a carrier of pathogenic
+micro-organisms had been established, and before the Protozoa
+were generally regarded as of importance in the causation of disease.
+The next important step was taken in 1889 when Smith and Kilbourne
+conclusively showed that the so-called Texas fever of cattle,
+in the United States, is due to an intracorpuscular blood parasite
+transmitted exclusively by a tick. This discovery, antedating by
+eight years the work on the relation of the mosquito to malaria, had a
+very great influence on subsequent studies along these lines.</p>
+
+<p>While much of the recent work has dealt with the true insects,
+or hexapods, it is now known that several of the most serious diseases
+of animals, and at least two important diseases of man are tick
+borne. These belong to the types known collectively as <i>babesioses</i>
+(or "<i>piroplasmoses</i>"), and <i>spirochætoses</i>.<span class="pagenum"><a name="Page_222" id="Page_222">[Pg 222]</a></span></p>
+
+<p>The term <i>babesiosis</i> is applied to a disease of man or animals
+which is caused by minute protozoan parasites of the genus <i>Babesia</i>,
+living in the red blood corpuscles. These parasites have usually been
+given the generic name <i>Piroplasma</i> and hence the type of disease
+which they cause is often referred to as "<i>piroplasmosis</i>." The best
+known illustration is the disease known in this country as Texas
+fever of cattle.</p>
+
+
+<p><a name="Cattle_Ticks_and_Texas_Fever" id="Cattle_Ticks_and_Texas_Fever"></a><b>Cattle Ticks and Texas Fever</b>&mdash;The cattle disease, which in the
+United States is known as Texas fever, is a widely distributed, exceedingly
+acute disease. In Australia it is known as <i>redwater fever</i> and
+in Europe as hæmoglobinuria, due to the fact that the urine of the
+diseased animals is discolored by the breaking down of the red blood
+corpuscles infested by the parasite.</p>
+
+<p>In their historical discussion, Smith and Kilbourne, point out that
+as far back as 1796 it was noted that Southern cattle, in a state of
+apparent health, might spread a fatal disease among Northern herds.
+As observations accumulated, it was learned that this infection was
+carried only during the warm season of the year and in the depth of
+winter Southern cattle were harmless. Moreover, Southern cattle
+after remaining for a short time in the North lost their power to
+transmit the disease, and the same was true of cattle which had been
+driven for a considerable distance.</p>
+
+<p>Very significant was the fact that the infection was not communicated
+directly from the Southern to Northern cattle but that
+the ground over which the former passed was infected by them, and
+that the infection was transmitted thence to susceptible cattle <i>after
+a period of not less than thirty days had elapsed</i>.</p>
+
+<p>Of course a disease as striking as this, and which caused such
+enormous losses of cattle in the region invaded was fruitful in theories
+concerning its causation. The most widespread was the belief that
+pastures were infected by the saliva, urine, or manure of Southern
+cattle. There were not wanting keen observers who suggested that
+the disease was caused by ticks, but little weight was given to their
+view.</p>
+
+<p>Various workers had described bacteria which they had isolated
+from the organs of the diseased animals, but their findings could not
+be verified. In 1889, Smith and Kilbourne discovered a minute,
+pear-shaped organism (<a href="#Fig_138">fig.&nbsp;138</a>) in the red blood corpuscles of a cow
+which had succumbed to Texas fever. On account of their shape<span class="pagenum"><a name="Page_223" id="Page_223">[Pg 223]</a></span>
+they were given the generic name <i>Pyrososma</i> and because they were
+usually found two in a corpuscle, the specific name, <i>bigeminum</i>. It
+is now generally accepted that
+the parasite is the same which
+Babes had observed the year
+before in Roumanian cattle
+suffering from hæmoglobinuria,
+and should be known as <i>Babesia
+bovis</i> (Babes).</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_138" id="Fig_138"></a>
+<a href="images/f138-full.png"><img src="images/f138.png" width="400" height="241" alt="138. Babesia bovis in blood corpuscles.
+After Calli." title="138. Babesia bovis in blood corpuscles.
+After Calli." /></a>
+<span class="caption">138. Babesia bovis in blood corpuscles.
+After Calli.</span>
+</div>
+
+<div class="figcenter" style="width: 245px;"><a name="Fig_139" id="Fig_139"></a>
+<a href="images/f139-full.png"><img src="images/f139.png" width="245" height="522" alt="139. The cattle tick (Boophilus annulatus).
+(a) Female; (b) male. After
+Comstock." title="139. The cattle tick (Boophilus annulatus).
+(a) Female; (b) male. After
+Comstock." /></a>
+<span class="caption">139. The cattle tick (Boophilus annulatus).
+(<i>a</i>)&nbsp;Female; (<i>b</i>)&nbsp;male. After
+Comstock.</span>
+</div>
+
+<p>By a series of perfectly conclusive
+experiments carried on
+near Washington, D.C., Smith
+and Kilbourne showed that
+this organism was carried from Southern cattle to non-immune animals
+by the so-called Southern cattle
+tick, <i>Boophilus annulatus</i> (= <i>Margaropus
+annulatus</i>) (<a href="#Fig_139">fig.&nbsp;139</a>).</p>
+
+<p>Of fourteen head of native cattle
+placed in a field with tick-infested
+Northern cattle all but two contracted
+the disease. This experiment was
+repeated with similar results. Four
+head of native cattle kept in a plot
+with three North Carolina cattle
+which had been carefully freed from
+ticks remained healthy. A second
+experiment the same year gave similar
+results.</p>
+
+<p>Still more conclusive was the experiment
+showing that fields which
+had not been entered by Southern
+cattle but which had been infected by
+mature ticks taken from such animals
+would produce Texas fever in native
+cattle. On September 13, 1889, several
+thousand ticks collected from
+cattle in North Carolina three and
+four days before, were scattered in a
+small field near Washington. Three
+out of four native animals placed in<span class="pagenum"><a name="Page_224" id="Page_224">[Pg 224]</a></span>
+this field contracted the disease. The fourth animal was not
+examined as to its blood but it showed no external symptoms of
+the disease.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_140" id="Fig_140"></a>
+<a href="images/f140-full.png"><img src="images/f140.png" width="500" height="383" alt="140. Hyalomma ægypticum. After Nuttall and Warburton." title="140. Hyalomma ægypticum. After Nuttall and Warburton." /></a>
+<span class="caption">140. Hyalomma ægypticum. After Nuttall and Warburton.</span>
+</div>
+
+<p>In these earlier experiments it was believed that the cattle tick
+acted as a carrier of the disease between the Southern cattle and the
+<i>soil</i> of the Northern pastures. "It was believed that the tick obtained
+the parasite from the blood of its host and in its dissolution
+on the pasture a certain resistant spore form was set free which
+produced the disease when taken in with the food." The feeding of
+one animal for some time with grass from the most abundantly
+infected field, without any appearance of the disease, made this
+hypothesis untenable.</p>
+
+<p>In the experimental work in 1890 the astonishing fact was brought
+out that the disease was conveyed neither by infected ticks disintegrating
+nor by their directly transferring the parasite, but that
+it was conveyed by the young hatched from eggs of infected ticks.
+In other words, the disease was hereditarily transferred to ticks of
+the second generation and they alone were capable of conveying it.</p>
+
+<p>Thus was explained the fact that Texas fever did not appear
+immediately along the route of Southern cattle being driven to
+Northern markets but that after a certain definite period it manifested
+itself. It was conveyed by the progeny of ticks which had
+dropped from the Southern cattle and deposited their eggs on the
+ground.<span class="pagenum"><a name="Page_225" id="Page_225">[Pg 225]</a></span></p>
+
+<p>These results have been fully confirmed by workers in different
+parts of the world,&mdash;notably by Koch, in Africa, and by Pound, in
+Australia.</p>
+
+<p>The disease is apparently transmitted by <i>Boophilus annulatus</i>
+alone, in the United States, but it, or an almost identical disease,
+is conveyed by <i>Ixodes hexagonus</i> in Norway, <i>Ixodes ricinus</i> in Finland
+and France and by the three species, <i>Boophilus decoloratus</i>, <i>Hyalomma
+ægypticum</i> (fig.&nbsp;<a href="#Fig_140">140</a> and&nbsp;<a href="#Fig_141">141</a>), and <i>Hæmaphysalis punctata</i> in Africa.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_141" id="Fig_141"></a>
+<a href="images/f141-full.png"><img src="images/f141.png" width="500" height="413" alt="141. Hyalomma aegypticum. Capitulum of female;
+(a) dorsal, (b) ventral aspect." title="141. Hyalomma aegypticum. Capitulum of female;
+(a) dorsal, (b) ventral aspect." /></a>
+<span class="caption">141. Hyalomma aegypticum. Capitulum of female;
+(<i>a</i>)&nbsp;dorsal, (<i>b</i>)&nbsp;ventral aspect.</span>
+</div>
+
+<p>In spite of the detailed study which it has received, the life cycle
+of <i>Babesia bovis</i> has not been satisfactorily worked out. The asexual
+reproduction in the
+blood of the vertebrate
+host has been described
+but the cycle in the tick
+is practically unknown.</p>
+
+<p>More successful
+attempts have been
+made to work out the life
+cycle of a related species,
+<i>Babesia canis</i>, which
+causes malignant jaundice
+in dogs in Africa
+and parts of Southern
+Europe. In this instance,
+also, the disease
+is transmitted by heredity to the ticks of the second generation.
+Yet the larval, or "seed ticks," from an infected female are not
+capable of conveying the disease, but only the nymphs and adults.
+Still more complicated is the condition in the case of <i>Babesia ovis</i> of
+sheep, which Motas has shown can be conveyed solely by the adult,
+sexually mature ticks of the second generation.</p>
+
+<p>In <i>Babesia canis</i>, Christopher (1907) observed developmental
+stages in the tick. He found in the stomach of adult ticks, large
+motile club-shaped bodies which he considered as oökinetes. These
+bodies pass to the ovaries of the tick and enter the eggs where they
+become globular in form and probably represent an oocyst. This
+breaks up into a number of sporoblasts which enter the tissues of
+the developing tick and give rise to numerous sporozoites, which
+collect in the salivary glands and thence are transferred to the
+vertebrate host. A number of other species of <i>Babesia</i> are known<span class="pagenum"><a name="Page_226" id="Page_226">[Pg 226]</a></span>
+to infest vertebrates and in all the cases where the method has been
+worked out it has been found that the conveyal was by ticks. We
+shall not consider the cases more fully here, as we are concerned
+especially with the method of transfer of human diseases.</p>
+
+
+<p><a name="Ticks_and_Rocky_Mountain_Spotted_Fever_of_Man" id="Ticks_and_Rocky_Mountain_Spotted_Fever_of_Man"></a><b>Ticks and Rocky Mountain Spotted Fever of Man</b>&mdash;Ever since
+1873 there has been known in Montana and Idaho a peculiar febrile
+disease of man, which has gained the name of "Rocky Mountain
+spotted fever." Its onset is marked by chills and fever which rapidly
+become acute. In about four to seven days there appears a characteristic
+eruption on the wrists, ankles or back, which quickly covers
+the body.</p>
+
+<p>McClintic (1912) states that the disease has now been reported
+from practically all of the Rocky Mountain States, including Arizona,
+California, Colorado, Idaho, Montana, Nevada, Oregon, Utah,
+Washington, and Wyoming. "Although the disease is far more
+prevalent in Montana and Idaho than in any of the other States,
+its spread has assumed such proportions in the last decade as to call
+for the gravest consideration on the part of both the state and national
+health authorities. In fact, the disease has so spread from state
+to state that it has undoubtedly become a very serious interstate
+problem demanding the institution of measures for its control and
+suppression."</p>
+
+<p>A peculiar feature of the Rocky Mountain spotted fever is a
+marked variation in its severity in different localities. In Montana,
+and especially in the famous Bitter Root Valley, from 33 per cent to
+75 per cent of the cases result fatally. On the other hand, the fatality
+does not exceed four per cent in Idaho.</p>
+
+<p>In 1902, Wilson and Chowning reported the causative organism
+of spotted fever to be a blood parasite akin to the <i>Babesia</i> of Texas
+fever, and made the suggestion that the disease was tick-borne.
+The careful studies of Stiles (1905) failed to confirm the supposed
+discovery of the organism, and the disease is now generally classed
+as due to an invisible virus. On the other hand, the accumulated
+evidence has fully substantiated the hypothesis that it is tick-borne.</p>
+
+<p>According to Ricketts (1907) the experimental evidence in support
+of this hypothesis was first afforded by Dr. L. P. McCalla and
+Dr. H. A. Brereton, in 1905. These investigators transmitted the
+disease from man to man in two experiments. "The tick was
+obtained 'from the chest of a man very ill with spotted fever' and<span class="pagenum"><a name="Page_227" id="Page_227">[Pg 227]</a></span>
+'applied to the arm of a man who had been in the hospital for two
+months and a half, and had lost both feet from gangrene due to
+freezing.' On the eighth day the patient became very ill and passed
+through a mild course of spotted fever, leaving a characteristic
+eruption. The experiment was repeated by placing the tick on a
+woman's leg and she likewise was infected with spotted fever."</p>
+
+<p>The most detailed studies were those of the late Dr. H. T. Ricketts,
+and it was he who clearly established the tick hypothesis. In the
+summer of 1906 he found that guinea pigs and monkeys are very
+susceptible to spotted fever and can readily be infected by inoculation
+of blood from patients suffering from the disease. This opened
+the way to experimental work on tick transmission. A female tick
+was fed upon an infected guinea pig for two days, removed and
+isolated for two days and then placed upon a healthy guinea pig.
+After an incubation period of three and a half days the experimental
+animal contracted a well-marked case of the disease.</p>
+
+<p>A similar result was obtained at the same time by King, and later
+in the season Ricketts proved that the male tick was also capable
+of transmitting the disease. He found that there was a very intimate
+relation of the virus to the tick and that the transmission must
+be regarded as biological throughout. Ticks remained infective as
+long as they lived and would feed for a period of several months. If
+they acquired the disease in the larval or nymphal stage they retained
+it during molting and were infective in the subsequent stages. In a
+few cases the larvæ from an infected female were infective.</p>
+
+<p>The evidence indicated that the tick suffers from a relatively
+harmless, generalized infection and the virus proliferates in its
+body. The disease probably is transferred through the salivary
+secretion of the tick since inoculation experiments show that the
+salivary glands of the infected adult contain the virus.</p>
+
+<p>It is probable that in nature the reservoir of the virus of spotted
+fever is some one or more of the native small animals. Infected
+ticks have been found in nature, and as various wild animals are
+susceptible to the disease, it is obvious that it may exist among them
+unnoticed. Wilson and Chowning suggested that the ground squirrel
+plays the principal rôle.</p>
+
+<p>Unfortunately, much confusion exists regarding the correct
+name of the tick which normally conveys the disease. In the medical
+literature it is usually referred to as <i>Dermacentor occidentalis</i>,
+but students of the group now agree that it is specifically distinct.<span class="pagenum"><a name="Page_228" id="Page_228">[Pg 228]</a></span>
+Banks has designated it as <i>Dermacentor venustus</i> and this name is
+used in the publications of the Bureau of Entomology. On the other
+hand, Stiles maintains that the common tick of the Bitter Root
+Valley, and the form which has been collected by the authors who
+have worked on Rocky Mountain spotted fever in that region, is
+separable from <i>D. venustus</i>, and he has described it under the name of
+<i>Dermacentor andersoni</i>.</p>
+
+<p>Mayer (1911) has shown experimentally that spotted fever may
+be transmitted by several different species of ticks, notably <i>Dermacentor
+marginatus</i>, <i>Dermacentor variabilis</i> and <i>Amblyomma americanum</i>.
+This being the case, the question of the exact systematic status of
+the species experimented upon in the Bitter Root Valley becomes
+less important, for since <i>Dermacentor occidentalis</i>, <i>Dermacentor
+venustus</i> and <i>Dermacentor andersoni</i> all readily attack man, it is
+probable that either species would readily disseminate the disease
+if it should spread into their range.</p>
+
+<p>Hunter and Bishop (1911) have emphasized the fact that in the
+eastern and southern United States there occur several species which
+attack man, and any one of which might transmit the disease from
+animal to animal and from animal to man. The following species,
+they state, would probably be of principal importance in the Southern
+and Eastern States: the lone star tick (<i>Amblyomma americanum</i>);
+the American dog tick (<i>Dermacentor variabilis</i>); and the gulf-coast
+tick (<i>Amblyomma maculatum</i>). In the extreme southern portions of
+Texas, <i>Amblyomma cajennense</i>, is a common pest of man.</p>
+
+<p>Since the evidence all indicates that Rocky Mountain spotted
+fever is transmitted solely by the tick, and that some of the wild
+animals serve as reservoirs of the virus, it is obvious that personal
+prophylaxis consists in avoiding the ticks as fully as possible, and in
+quickly removing those which do attack. General measures along
+the line of tick eradication must be carried out if the disease is to be
+controlled. That such measures are feasible has been shown by the
+work which has been done in controlling the tick-borne Texas fever
+of cattle, and by such work as has already been done against the
+spotted fever tick, which occurs on both wild and domestic animals.
+Detailed consideration of these measures is to be found in the
+publications of the Public Health and Marine Hospital Service,
+and the Bureau of Entomology. Hunter and Bishopp give the
+following summarized recommendations for control or eradication
+measures in the Bitter Root Valley.<span class="pagenum"><a name="Page_229" id="Page_229">[Pg 229]</a></span></p>
+
+<p>(1) A campaign of education, whereby all the residents of the
+valley will be made thoroughly familiar with the feasibility of the
+plan of eradication, and with what it will mean in the development of
+the valley.</p>
+
+<p>(2) The obtaining of legislation to make it possible to dip or oil
+all live stock in the Bitter Root Valley.</p>
+
+<p>(3) The obtaining of an accurate census of the horses, cattle,
+sheep, mules, and dogs in the valley.</p>
+
+<p>(4) The construction of ten or more dipping vats.</p>
+
+<p>(5) The providing of materials to be used in the dipping mixture.</p>
+
+<p>(6) The organization of a corps of workers to carry on the operations.</p>
+
+<p>(7) The systematic dipping of the horses, cattle, sheep, and dogs
+of the valley on a definite weekly schedule from approximately March
+10 to June 9.</p>
+
+<p>(8) The treatment by hand of the animals in localities remote
+from vats, on the same schedule.</p>
+
+<p>They estimate that after three seasons' operations a very small
+annual expenditure would provide against reinfestation of the valley
+by the incoming of cattle from other places.</p>
+
+<p>Supplementary measures consist in the killing of wild mammals
+which may harbor the tick; systematic burning of the brush and
+debris on the mountain side; and in clearing, since the tick is seldom
+found on land under cultivation.<span class="pagenum"><a name="Page_230" id="Page_230">[Pg 230]</a></span></p>
+
+
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="CHAPTER_X" id="CHAPTER_X"></a>CHAPTER X</h2>
+
+<h2>ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA
+[<i>Continued</i>]</h2>
+
+
+<h3><a name="Arthropods_and_Spirochaetoses_of_Man_and_Animals" id="Arthropods_and_Spirochaetoses_of_Man_and_Animals"></a><span class="smcap">Arthropods and Spirochætoses of Man and Animals</span></h3>
+
+<p>The term spirochætoses is applied to diseases of man or animals
+which are due to protistan parasites belonging to the group of slender,
+spiral organisms known as spirochætes.</p>
+
+<p>There has been much discussion concerning the relationship Of
+the spirochætes. Formerly, they were regarded as bacteria closely
+related to the forms grouped in the genus <i>Spirillum</i>. The results
+of the detailed study which the spirochætes have received in
+recent years, have led most of the workers to consider them as belonging
+to the protozoa. The merits of the discussion we are not concerned
+with here, but rather with the fact that a number of diseases
+caused by spirochætes are arthropod-borne. The better known of
+these we shall discuss.</p>
+
+
+<p><a name="African_Relapsing_Fever_of_Man" id="African_Relapsing_Fever_of_Man"></a><b>African Relapsing Fever of Man</b>&mdash;It has long been known to the
+natives of Africa and to travelers in that country, that the bite of a
+certain tick, <i>Ornithodoros moubata</i>, may be followed by severe or
+even fatal fever of the relapsing type. Until recent years, it was
+supposed that the effect was due to some special virulence of the tick,
+just as nagana of cattle was attributed to the direct effect of the bite
+of the tsetse-fly. The disease is commonly known as "tick-fever"
+or by the various native names of the tick.</p>
+
+<p>In 1904, Ross and Milne, in Uganda, and Dutton and Todd on the
+Congo, discovered that the cause of the disease is a spirochæte which
+is transmitted by the tick. This organism has been designated by
+Novy and Knapp as <i>Spirochæta duttoni</i>.</p>
+
+<p><i>Ornithodoros moubata</i> (<a href="#Fig_142">fig.&nbsp;142</a>), the carrier of African relapsing
+fever, or "tick-fever," is widely distributed in tropical Africa, and
+occurs in great numbers in the huts of natives, in the dust, cracks
+and crevices of the dirt floors, or the walls. It feeds voraciously
+on man as well as upon birds and mammals. Like others of the
+<i>Argasidæ</i>, it resembles the bed-bug in its habit of feeding primarily
+at night. Dutton and Todd observed that the larval stage is undergone
+in the egg and that the first free stage is that of the octopod
+nymph.<span class="pagenum"><a name="Page_231" id="Page_231">[Pg 231]</a></span></p>
+
+<div class="figcenter" style="width: 375px;"><a name="Fig_142" id="Fig_142"></a>
+<a href="images/f142-full.png"><img src="images/f142.png" width="375" height="661" alt="142. Ornithodoros moubata. (a) Anterior part of venter; (b) second stage
+nymph; (c) capitulum; (d) dorsal and (e) ventral aspect of female;
+(f) ventral aspect of nymph; (g) capitulum of nymph. After Nuttall
+and Warburton." title="142. Ornithodoros moubata. (a) Anterior part of venter; (b) second stage
+nymph; (c) capitulum; (d) dorsal and (e) ventral aspect of female;
+(f) ventral aspect of nymph; (g) capitulum of nymph. After Nuttall
+and Warburton." /></a>
+<span class="caption">142. Ornithodoros moubata. (<i>a</i>)&nbsp;Anterior part of venter; (<i>b</i>)&nbsp;second stage
+nymph; (<i>c</i>)&nbsp;capitulum; (<i>d</i>)&nbsp;dorsal and (<i>e</i>)&nbsp;ventral aspect of female;
+(<i>f</i>)&nbsp;ventral aspect of nymph; (<i>g</i>)&nbsp;capitulum of nymph. After Nuttall
+and Warburton.</span>
+</div><p><span class="pagenum"><a name="Page_232" id="Page_232">[Pg 232]</a></span></p>
+
+<p>The evidence that the fever is transmitted by this tick is conclusive.
+Koch found that from five per cent to fifteen per cent, and
+in some places, fifty per cent of the ticks captured, harbored the
+spirochæte. The disease is readily transmitted to monkeys, rats,
+mice and other animals and the earlier experiments along these lines
+have been confirmed by many workers.</p>
+
+<p>Not only are the ticks which have fed on infected individuals
+capable of conveying the disease to healthy animals but they transmit
+the causative organism to their progeny. Thus Möllers (1907),
+working in Berlin, repeatedly infected monkeys through the bites
+of nymphs which had been bred in the laboratory from infected ticks.
+Still more astonishing was his discovery that ticks of the third generation
+were infective. In other words, if the progeny of infected ticks
+were fed throughout life on healthy animals, and on maturity deposited
+eggs, the nymphs which hatched from these eggs would still
+be capable of carrying the infection.</p>
+
+<p>The developmental cycle of the spirochæte within the tick has not
+been fully worked out, though the general conclusions of Leishman
+(1910) have been supported by the recent works of Balfour (1911
+and 1912), and Hindle (1912), on the life cycle of spirochætes affecting
+fowls.</p>
+
+<p><i>Spirochæta duttoni</i> ingested by <i>Ornithodoros moubata</i> apparently
+disappear within a few days, but Leishman believed that in reality
+they break up into minute granules which are to be found in the
+alimentary canal, the salivary glands and the Malpighian tubes of
+the tick. These granules, or "coccoid bodies," as Hindle calls them,
+are supposed to be the form in which the spirochætes infect the new
+host. We shall see later that Marchoux and Couvy (1913) dissent
+wholly from this interpretation.</p>
+
+<p>According to Leishman, and Hindle, the coccoid bodies are not
+injected into the vertebrate host with the saliva of the tick, as are
+the sporozoites of malaria with that of the mosquito. Instead, they
+pass out with the excrement and secondarily gain access to the
+wound inflicted by the tick.</p>
+
+<p>Nuttall (1912) calls attention to the fact that the geographical
+distribution of <i>Ornithodoros moubata</i> is far wider than our present
+records show for the distribution of the relapsing fever in man and
+that there is every reason to fear the extension of the disease. Huts
+where the ticks occur should be avoided and it should be remembered
+that in infected localities there is special danger in sleeping on the
+ground.<span class="pagenum"><a name="Page_233" id="Page_233">[Pg 233]</a></span></p>
+
+
+<p><a name="European_Relapsing_Fever" id="European_Relapsing_Fever"></a><b>European Relapsing Fever</b>&mdash;There is widely distributed in Europe
+a type of relapsing fever which is caused by <i>Spirochæta recurrentis</i>.
+It has long been supposed that this disease is spread by the bed-bug
+and there is some experimental evidence to show that it may be
+conveyed by these insects.</p>
+
+<p>In 1897, Tictin found that he could infect monkeys by inoculating
+the contents of bed-bugs which had fed upon a patient within forty-eight
+hours. Nuttall, in 1907, in one experiment succeeded in transmitting
+<i>Spirochæta recurrentis</i> from mouse to mouse by bites of bed-bugs.
+The bugs, thirty-five in number, were transferred at short
+intervals from one mouse to another, not being allowed to take a
+full meal on the first, or infected mouse.</p>
+
+<p>On the other hand, there is much clinical evidence to show that
+the European relapsing fever like various other types of the disease
+is transmitted from man to man by head and body lice (<i>Pediculus
+humanus</i> and <i>Pediculus corporis</i>).</p>
+
+<p>Interesting supplementary evidence is that of Bayon's observations
+(1912), in Moscow. "Having visited the big municipal night hospitals
+at Moscow I soon noticed that they were kept with such scrupulous
+cleanliness, disinfected so lavishly, the beds of iron, the floor cemented,
+that it was not possible for bed-bugs to thrive to any extent on
+the premises. The people sleeping there were allowed, however,
+to sleep in their own clothes. The introduction of these model homes
+had not had any effect on the incidence of relapsing fever, for the
+places were still hot-beds of the fever during winter. On the other
+hand, though I changed my rooms several times, I found bugs in
+every successive lodging, and I was told in Moscow, this can hardly
+be avoided. Yet no foreigner, or Russian of the better class, ever
+catches relapsing fever. To this may be added the fact that when
+I asked for clothes-lice and promised to pay a kopec for two, the
+attendants from the night hostel brought me next morning a small
+ounce bottle crammed with <i>Pediculus capitis</i> (= <i>P. humanus</i>), and
+<i>Pediculus vestimentorum</i> (= <i>P. corporis</i>) collected off the sleepers.
+If relapsing fever were transmitted by bed-bugs, it would be much
+more disseminated than it is at present in Moscow."</p>
+
+<p>Direct experimental evidence of the agency of lice in transmitting
+relapsing fever is especially clear in the case of a type of the disease
+prevalent in parts of North Africa. We shall consider this evidence
+later.<span class="pagenum"><a name="Page_234" id="Page_234">[Pg 234]</a></span></p>
+
+
+<p><a name="Other_Types_of_Relapsing_Fever_of_Man" id="Other_Types_of_Relapsing_Fever_of_Man"></a><b>Other Types of Relapsing Fever of Man</b>&mdash;In addition to the three
+types of human relapsing fever already referred to, several others
+have been distinguished and have been attributed to distinct species
+of spirochætes. The various spirochætoses of man are:</p>
+
+<p>African, caused by <i>S. duttoni</i>; European, caused by <i>S. recurrentis</i>;
+North African, caused by <i>S. berbera</i>; East African, caused
+by <i>S. rossi</i>; East Indian, caused by <i>S. carteri</i>; North American,
+caused by <i>S. novyi</i>; South American, caused by <i>S. duttoni</i> (?).</p>
+
+<p>Nuttall (1912) in his valuable résumé of the subject, has emphasized
+that "in view of the morphological similarity of the supposedly
+different species of spirochætes and their individual variations
+in virulence, we may well doubt if any of the 'species' are valid.
+As I pointed out four years ago, the various specific names given to
+the spirochætes causing relapsing fever in man may be used merely
+for convenience <i>to distinguish strains or races</i> of different origin.
+They cannot be regarded as valid names, in the sense of scientific
+nomenclature, for virulence and immunity reactions are not adequate
+tests of specificity."</p>
+
+
+<p><a name="North_African_Relapsing_Fever_of_Man" id="North_African_Relapsing_Fever_of_Man"></a><b>North African Relapsing Fever of Man</b>&mdash;The type of human
+relapsing fever to be met with in Algeria, Tunis, and Tripoli, is due to
+a <i>Spirochæta</i> to which does not differ morphologically from <i>Spirochæta
+duttoni</i>, but which has been separated on biological grounds as
+<i>Spirochæta berberi</i>.</p>
+
+<p>Experimenting with this type of disease in Algeria, Sergent and
+Foly (1910), twice succeeded in transmitting it from man to monkeys
+by inoculation of crushed body lice and in two cases obtained infection
+of human subjects who had received infected lice under their
+clothing and who slept under coverings harboring many of the lice
+which had fed upon a patient. Their results were negative with
+<i>Argas persicus</i>, <i>Cimex lectularius</i>, <i>Musca domestica</i>, <i>Hæmatopinus
+spinulosus</i> and <i>Ceratophyllus fasciatus</i>. They found body lice
+associated with every case of relapsing fever which they found in
+Algeria.</p>
+
+<p>Nicolle, Blaizot, and Conseil (1912) showed that the louse did
+not transmit the parasite by its bite. Two or three hours after it
+has fed on a patient, the spirochætes begin to break up and finally
+they disappear, so that after a day, repeated examinations fail to
+reveal them. They persist, nevertheless, in some unknown form,
+for if the observations are continued they reappear in eight to twelve<span class="pagenum"><a name="Page_235" id="Page_235">[Pg 235]</a></span>
+days. These new forms are virulent, for a monkey was infected
+by inoculating a single crushed louse which had fed on infected blood
+fifteen days before.</p>
+
+<p>Natural infection is indirect. Those attacked by the insect
+scratch, and in this act they excoriate the skin, crush the lice and
+contaminate their fingers. The least abrasion of the skin serves for
+the entrance of the spirochætes. Even the contact of the soiled
+fingers on the various mucosa, such as the conjunctive of the eye,
+is sufficient.</p>
+
+<p>As in the case of <i>Spirochæta duttoni</i>, the organism is transmitted
+hereditarily in the arthropod vector. The progeny of lice which
+have fed on infected blood may themselves be infective.</p>
+
+
+<p><a name="Spirochaetosis_of_Fowls" id="Spirochaetosis_of_Fowls"></a><b>Spirochætosis of Fowls</b>&mdash;One of the best known of the spirochætes
+transmitted by arthropods is <i>Spirochæta gallinarum</i>, the cause of a
+very fatal disease of domestic fowls in widely separated regions of
+the world. According to Nuttall, it occurs in Southeastern Europe,
+Asia, Africa, South America and Australia.</p>
+
+<p>In 1903, Marchoux and Salimbeni, working in Brazil, made the
+first detailed study of the disease, and showed that the causative
+organism is transmitted from fowl to fowl by the tick <i>Argas persicus</i>.
+They found that the ticks remained infective for at least five months.
+Specimens which had fed upon diseased birds in Brazil were sent to
+Nuttall and he promptly confirmed the experiments. Since that
+date many investigators, notably Balfour and Hindle, have contributed
+to the elucidating of the life-cycle of the parasite. Since it
+has been worked out more fully than has that of any of the human
+spirochætes, we present Hindle's diagram (<a href="#Fig_143">fig.&nbsp;143</a>) and quote the
+brief summary from his preliminary paper (1911<i>b</i>).</p>
+
+<p>"Commencing with the ordinary parasite in the blood of the fowl,
+the spirochæte grows until it reaches a certain length (16-19µ) and
+then divides by transverse division. This process is repeated, and
+is probably the only method of multiplication of the parasite within
+the blood. When the spirochætes disappear from the circulation,
+some of them break up into the coccoid bodies which, however,
+do not usually develop in the fowl. When the spirochætes are
+ingested by <i>Argas persicus</i>, some of them pass through the gut wall
+into the c&oelig;lomic fluid. From this medium they bore their way into
+the cells of the various organs of the tick and there break up into a
+number of coccoid bodies. These intracellular forms multiply by<span class="pagenum"><a name="Page_236" id="Page_236">[Pg 236]</a></span>
+ordinary fission in the cells of the Malpighian tubules and gonads.
+Some of the coccoid bodies are formed in the lumen of the gut and
+Malpighian tubules. The result is that some of the coccoid bodies
+may be present in the Malpighian secretion and excrement of an
+infected tick and when mixed with the coxal fluid may gain entry
+into another fowl by the open wound caused by the tick's bite. They
+then elongate and redevelop into ordinary spirochætes in the blood
+of the fowl, and the cycle may be repeated."</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_143" id="Fig_143"></a>
+<a href="images/f143-full.png"><img src="images/f143.png" width="500" height="483" alt="143. Spirochæta gallinarum. After Hindle." title="143. Spirochæta gallinarum. After Hindle." /></a>
+<span class="caption">143. Spirochæta gallinarum. After Hindle.</span>
+</div>
+
+<p>Hindle's account is clear cut and circumstantial, and is quite in
+line with the work of Balfour, and of Leishman. Radically different
+is the interpretation of Marchoux and Couvy (1913). These investigators
+maintain that the granules localized in the Malpighian tubules
+in the larvæ and, in the adult, also in the ovules and the genital ducts
+of the male and female, are not derived from spirochætes but that they
+exist normally in many acariens. They interpret the supposed<span class="pagenum"><a name="Page_237" id="Page_237">[Pg 237]</a></span>
+disassociation of the spirochæte into granules as simply the first
+phase, not of a process of multiplication, but of a degeneration
+ending in the death of the parasite. The fragmented chromatin
+has lost its affinity for stains, remaining always paler than that of
+the normal spirochætes. On the other hand, the granules of Leishman
+stain energetically with all the basic stains.</p>
+
+<p>Further, according to Marchoux and Couvy, infection takes
+place without the emission of the coxal fluid and indeed, soiling of the
+host by the coxal fluid diluting the excrement is exceptional. All
+of the organs of the Argasid are invaded by the parasites, but they
+pass from the c&oelig;lom into the acini of the salivary glands and collect
+in its efferent canal. The saliva serves as the vehicle of infection.</p>
+
+<p>Thus, the question of the life cycle of <i>Spirochæta gallinarum</i>, and
+of spirochætes in general, is an open one.</p>
+
+<p>It should be noted that <i>Argas persicus</i>, the carrier of <i>Spirochæta
+gallinarum</i>, is a common pest of poultry in the southwestern United
+States. Though the disease has not been reported from this country,
+conditions are such that if accidentally introduced, it might do great
+damage.</p>
+
+
+<p><a name="Other_Spirochaete_Diseases_of_Animals" id="Other_Spirochaete_Diseases_of_Animals"></a><b>Other Spirochæte Diseases of Animals</b>&mdash;About a score of other
+blood inhabiting spirochætes have been reported as occurring in
+mammals, but little is known concerning their life-histories. One
+of the most important is <i>Spirochæta theileri</i> which produces a spirochætosis
+of cattle in the Transvaal. Theiler has determined that it
+is transmitted by an Ixodid tick, <i>Margaropus decoloratus</i>.</p>
+
+
+<h3><a name="Typhus_Fever_and_Pediculidae" id="Typhus_Fever_and_Pediculidae"></a><span class="smcap">Typhus Fever and Pediculidæ</span></h3>
+
+<p>Typhus is an acute, and continued fever, formerly epidemically
+prevalent in camps, hospitals, jails, and similar places where persons
+were crowded together under insanitary conditions. It is accompanied
+by a characteristic rash, which gives the disease the common
+name of "spotted" or "lenticular" fever. The causative organism
+is unknown.</p>
+
+<p>Typhus fever has not generally been supposed to occur in the
+United States, but there have been a few outbreaks and sporadic
+cases recognized. According to Anderson and Goldberger (1912<i>a</i>),
+it has been a subject of speculation among health authorities why,
+in spite of the arrival of occasional cases in this country and of many
+persons from endemic foci of the disease, typhus fever apparently
+does not gain a foothold in the United States. These same workers<span class="pagenum"><a name="Page_238" id="Page_238">[Pg 238]</a></span>
+showed that the so-called Brill's disease, studied especially in New
+York City, is identical with the typhus fever of Mexico and of
+Europe.</p>
+
+<p>The conditions under which the disease occurs and under which
+it spreads most rapidly are such as to suggest that it is carried by
+some parasitic insect. On epidemiological grounds the insects most
+open to suspicion are the lice, bed-bugs and fleas.</p>
+
+<p>In 1909, Nicolle, Comte and Conseil, succeeded in transmitting
+typhus fever from infected to healthy monkeys by means of the
+body louse (<i>Pediculus corporis</i>). Independently of this work,
+Anderson and Goldberger had undertaken work along this line in
+Mexico, and in 1910 reported two attempts to transmit the disease
+to monkeys by means of body lice. The first experiment resulted
+negatively, but the second resulted in a slight rise in temperature,
+and in view of later results it seems that this was due to infection
+with typhus.</p>
+
+<p>Shortly after, Ricketts and Wilder (1910) succeeded in transmitting
+the disease to the monkey by the bite of body lice in two experiments,
+the lice in one instance deriving their infection from a man
+and in another from the monkey. Another monkey was infected
+by typhus through the introduction of the feces and abdominal
+contents of infested lice into small incisions. Experiments with
+fleas and bed-bugs resulted negatively.</p>
+
+<p>Subsequently, Goldberger and Anderson (1912<i>b</i>) indicated that
+the head louse (<i>Pediculus humanus</i>) as well, may become infected
+with typhus. In an attempt to transmit typhus fever (Mexican
+virus) from man to monkey by subcutaneous injection of a saline
+suspension of crushed head lice, the monkeys developed a typical
+febrile reaction with subsequent resistance to an inoculation of
+virulent typhus (Mexican) blood. In one of the three experiments
+to transmit the disease from man to monkey by means of the bite
+of the head louse, the animal bitten by the presumably infected head
+lice proved resistant to two successive immunity tests with virulent
+typhus blood.</p>
+
+<p>In 1910, Ricketts and Wilder reported an experiment undertaken
+with a view to determining whether the young of infected lice were
+themselves infected. Young lice were reared to maturity on the
+bodies of typhus patients, so that if the eggs were susceptible to
+infection at any stage of their development, they would have every
+opportunity of being infected within the ovary. The eggs of these
+infected lice were obtained, they were incubated, and the young lice<span class="pagenum"><a name="Page_239" id="Page_239">[Pg 239]</a></span>
+of the second generation were placed on a normal rhesus monkey.
+The experimenters were unable to keep the monkey under very
+close observation during the following three or four weeks, but from
+the fact that he proved resistant to a subsequent immunity test
+they concluded that he probably owed this immunity to infection
+by these lice of the second generation.</p>
+
+<p>Anderson and Goldberger (1912<i>b</i>) object that due consideration
+was not given to the possibility of a variable susceptibility of the
+monkey to typhus. Their similar experiment was "frankly negative."</p>
+
+<p>Prophylaxis against typhus fever is, therefore, primarily a question
+of vermin extermination. A brief article by Dr. Goldberger
+(1914) so clearly shows the practical application of his work and that
+of the other investigators of the subject, that we abstract from it
+the following account:</p>
+
+<p>"In general terms it may be stated that association with a case of
+typhus fever in the absence of the transmitting insect is no more
+dangerous than is association with a case of yellow fever in the
+absence of the yellow fever mosquito. Danger threatens only when
+the insect appears on the scene."</p>
+
+<p>"We may say, therefore, that to prevent infection of the individual
+it is necessary for him only to avoid being bitten by the louse.
+In theory this may readily be done, for we know that the body louse
+infests and attaches itself almost entirely to the body linen, and that
+boiling kills this insect and its eggs. Individual prophylaxis is
+based essentially, therefore, on the avoidance of contact with individuals
+likely to harbor lice. Practically, however, this is not
+always as easy as it may seem, especially under the conditions of
+such intimate association as is imposed by urban life. Particularly
+is this the case in places such as some of the large Mexican cities,
+where a large proportion of the population harbors this vermin.
+Under such circumstances it is well to avoid crowds or crowded places,
+such as public markets, crowded streets, or public assemblies at
+which the 'peon' gathers."</p>
+
+<p>"Community prophylaxis efficiently and intelligently carried out
+is, from a certain point of view, probably easier and more effective
+in protecting the individual than is the individual's own effort to
+guard himself. Typhus emphasizes, perhaps better than any other
+disease, the fact that fundamentally, sanitation and health are
+economic problems. In proportion as the economic condition of the
+masses has improved&mdash;that is, in proportion as they could afford<span class="pagenum"><a name="Page_240" id="Page_240">[Pg 240]</a></span>
+to keep clean&mdash;the notorious filth disease has decreased or disappeared.
+In localities where it still prevails, its further reduction
+or complete eradication waits on a further improvement in, or extension
+of, the improved economic status of those afflicted. Economic
+evolution is very slow process, and, while doing what we can to hasten
+it, we must take such precautions as existing conditions permit,
+looking to a reduction in or complete eradication of the disease."</p>
+
+<p>"When possible, public bath houses and public wash houses,
+where the poor may bathe and do their washings at a minimum or
+without cost, should be provided. Similar provision should be
+made in military and construction camps. Troops in the field should
+be given the opportunity as frequently as possible to wash and <i>scald</i>
+or <i>boil</i> their body linen."</p>
+
+<p>"Lodging houses, cheap boarding houses, night shelters, hospitals,
+jails and prisons, are important factors in the spread and frequently
+constitute foci of the disease. They should receive rigid sanitary
+supervision, including the enforcement of measures to free all inmates
+of such institutions of lice on admission."</p>
+
+<p>"So far as individual foci of the disease are concerned these
+should be dealt with by segregating and keeping under observation
+all exposed individuals for 14 days&mdash;the period of incubation&mdash;from
+the last exposure, by disinfecting (boiling or steaming) the suspected
+bedding, body linen, and clothes, for the destruction of any possible
+vermin that they may harbor, and by fumigating (with sulphur)
+the quarters that they may have occupied."</p>
+
+<p>"It will be noted that nothing has been said as to the disposition
+of the patient. So far as the patient is concerned, he should be
+removed to 'clean' surroundings, making sure that he does not
+take with him any vermin. This may be done by bathing, treating
+the hair with an insecticide (coal oil, tincture of larkspur), and a
+complete change of body linen. Aside from this, the patient may
+be treated or cared for in a general hospital ward or in a private house,
+provided the sanitary officer is satisfied that the new surroundings
+to which the patient has been removed are 'clean,' that is, free
+from vermin. Indeed, it is reasonably safe to permit a 'clean'
+patient to remain in his own home if this is 'clean,' for, as has already
+been emphasized, there can be no spread in the absence of lice.
+This is a common experience in native families of the better class
+and of Europeans in Mexico City."</p>
+
+<p>"Similarly the sulphur fumigation above prescribed may be
+dispensed with as unnecessary in this class of cases."<span class="pagenum"><a name="Page_241" id="Page_241">[Pg 241]</a></span></p>
+
+
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="CHAPTER_XI" id="CHAPTER_XI"></a>CHAPTER XI</h2>
+
+<h2>SOME POSSIBLE, BUT IMPERFECTLY ESTABLISHED CASES OF
+ARTHROPOD TRANSMISSION OF DISEASE</h2>
+
+
+<h3><a name="Infantile_Paralysis_or_Acute_Anterior_Poliomyelitis" id="Infantile_Paralysis_or_Acute_Anterior_Poliomyelitis"></a><span class="smcap">Infantile Paralysis or Acute Anterior Poliomyelitis</span></h3>
+
+<p>The disease usually known in this country as infantile paralysis
+or, more technically, as acute anterior poliomyelitis, is one which
+has aroused much attention in recent years.</p>
+
+<p>The causative organism of infantile paralysis is unknown, but
+it has been demonstrated that it belongs to the group of filterable
+viruses. It gives rise to a general infection, producing characteristic
+lesions in the central nervous system. The result of the injury to
+the motor nerves is a more or less complete paralysis of the corresponding
+muscle. This usually manifests itself in the legs and arms.
+The fatal cases are usually the result of paralysis of the muscles
+of respiration. Of the non-fatal cases about 60 per cent remain
+permanently crippled in varying degrees.</p>
+
+<p>Though long known, it was not until about 1890 that it was
+emphasized that the disease occurs in epidemic form. At this time
+Medin reported his observations on an epidemic of forty-three cases
+which occurred in and around Stockholm in 1887. Since then,
+according to Frost (1911), epidemics have been observed with increasing
+frequency in various parts of the world. The largest recorded
+epidemics have been those in Vermont, 1894, 126 cases; Norway and
+Sweden, 1905, about 1,500 cases; New York City, 1907, about
+2,500 cases. Since 1907 many epidemics have been reported in the
+United States, and especially in the Northern States east of the
+Dakotas. In 1912 there were over 300 cases of the disease in Buffalo,
+N. Y., with a mortality of somewhat over 11 per cent.</p>
+
+<p>In view of the sudden prominence and the alarming spread of
+infantile paralysis, there have been many attempts to determine
+the cause, and the manner in which the disease spreads and develops
+in epidemic form. In the course of these studies, the question of
+possible transmission by insects was naturally suggested.</p>
+
+<p>C. W. Howard and Clark (1912) presented the results of studies
+in this phase of the subject. They dealt especially with the house-fly,
+bedbug, head, and body lice, and mosquitoes. It was found
+that the house-fly (<i>Musca domestica</i>) can carry the virus of poliomyelitis
+in an active state for several days upon the surface of the body<span class="pagenum"><a name="Page_242" id="Page_242">[Pg 242]</a></span>
+and for several hours within the gastro-intestinal tract. Mosquitoes
+and lice were found not to take up or maintain the virus. On the
+other hand, the bedbug (<i>Cimex lectularius</i>) was found to take the
+virus from the infected monkeys and to maintain it in a living state
+within the body for a period of seven days. This was demonstrated
+by grinding up in salt solution, insects which had fed on poliomyelitic
+animals and injecting the filtrate into a healthy monkey. The experimenters
+doubted that the bedbug is a carrier of the virus in nature.</p>
+
+<p>Earlier in the same year, Brues and Sheppard published the results
+of an intensive epidemiological study of the outbreak of 1911, in
+Massachusetts. Special attention had been paid to the possibility
+of insect transfer and the following conclusion was reached:</p>
+
+<p>"Field work during the past summer together with a consideration
+of the epidemiology of the disease so far as known, points strongly
+toward biting flies as possible carriers of the virus. It seems probable
+that the common stable-fly (<i>Stomoxys calcitrans</i> L.) may be responsible
+to a certain extent for the spread of acute epidemic poliomyelitis,
+possibly aided by other biting flies, such as <i>Tabanus lineola</i>. No
+facts which disprove such a hypothesis have as yet been adduced,
+and experiments based upon it are now in progress."</p>
+
+<p>As stated by Brues (1913), especial suspicion fell upon the stable-fly
+because:</p>
+
+<p>1. The blood-sucking habits of the adult fly suit it for the transfer
+of virus present in the blood.</p>
+
+<p>2. The seasonal abundance of the fly is very closely correlated
+with the incidence of the disease, rising rapidly during the summer
+and reaching a maximum in July and August, then slowly declining
+in September and October.</p>
+
+<p>3. The geographical distribution of the fly is, so far as can be
+ascertained, wider, or at least co-extensive with that of poliomyelitis.</p>
+
+<p>4. <i>Stomoxys</i> is distinctly more abundant under rural conditions,
+than in cities and thickly populated areas.</p>
+
+<p>5. While the disease spreads over districts quickly and in a
+rather erratic way, it often appears to follow along lines of travel,
+and it is known that <i>Stomoxys</i> flies will often follow horses for long
+distances along highways.</p>
+
+<p>6. In a surprisingly large number of cases, it appeared probable
+that the children affected had been in the habit of frequenting places
+where <i>Stomoxys</i> is particularly abundant, i.e., about stables, barnyards,
+etc.<span class="pagenum"><a name="Page_243" id="Page_243">[Pg 243]</a></span></p>
+
+<p>The experiments referred to were carried on during the summer of
+1912 and in September Dr. Rosenau announced that the disease was
+transferred by the bite of the stable-fly.</p>
+
+<p>A monkey infected by inoculation was exposed to the bites of
+upwards of a thousand of the <i>Stomoxys</i> flies daily, by stretching it
+at full length and rolling it in a piece of chicken wire, and then placing
+it on the floor of the cage in which the flies were confined. The flies
+fed freely from the first, as well as later, after paralysis had set in.
+Alternating with the inoculated monkey, healthy monkeys were
+similarly introduced into the cage at intervals. New monkeys were
+inoculated to keep a supply of such infected animals and additional
+healthy ones were exposed to the flies, which fed willingly and in
+considerable numbers on each occasion. "Thus the flies were given
+every opportunity to obtain infection from the monkeys, since the
+animals were bitten during practically every stage of the disease
+from the time of the inoculation of the virus till their death following
+the appearance of paralysis. By the same arrangement the
+healthy monkeys were likely to be bitten by flies that had previously
+fed during the various stages of the disease on the infected monkeys.
+The flies had meanwhile enjoyed the opportunity of incubating the
+virus for periods varying from the day or two which usually elapses
+between consecutive feedings, to the two or three-week period for
+which at least some (although a very small percentage) of the flies
+lived in the cage."</p>
+
+<p>"In all, twelve apparently healthy monkeys of a small Japan
+species were exposed to the flies in the manner described for the infected
+monkeys. Some were placed in the cage only once or twice
+and others a number of times after varying intervals. These exposures
+usually lasted for about half an hour, but were sometimes
+more protracted. No results were apparent until two or three
+weeks after the experiment was well under way, and then in rather
+rapid succession six of the animals developed symptoms of poliomyelitis.
+In three, the disease appeared in a virulent form, resulting
+in death, while the other three experienced transient tremblings,
+diarrh&oelig;a, partial paralysis and recovery."&mdash;Brues, 1913.</p>
+
+<p>Very soon after the announcement of the results of experiments
+by Rosenau and Brues, they were apparently conclusively confirmed
+by Anderson and Frost (1912), who repeated the experiments, at
+Washington. They announced that through the bites of the <i>Stomoxys</i>
+flies that had previously fed on infected monkeys, they had succeeded
+in experimentally infecting three healthy monkeys.<span class="pagenum"><a name="Page_244" id="Page_244">[Pg 244]</a></span></p>
+
+<p>The results of these experiments gained much publicity and in
+spite of the conservative manner in which they had been announced,
+it was widely proclaimed that infantile paralysis was conveyed in
+nature by the stable-fly and by it alone.</p>
+
+<p>Serious doubt was cast on this theory by the results of further
+experiments by Anderson and Frost, reported in May of 1913.
+Contrary to the expectations justified by their first experience, the
+results of all the later, and more extended, experiments were wholly
+negative. Not once were these investigators again able to transmit
+the infection of poliomyelitis through <i>Stomoxys</i>. They concluded that
+it was extremely doubtful that the insect was an important factor
+in the natural transmission of the disease, not only because of their
+series of negative results, "but also because recent experiments have
+afforded additional evidence of the direct transmissibility or contagiousness
+of poliomyelitis, and because epidemiological studies
+appear to us to indicate that the disease is more likely transmitted
+largely through passive human virus carriers."</p>
+
+<p>Soon after this, Kling and Levaditi (1913) published their detailed
+studies on acute anterior poliomyelitis. They considered that the
+experiments of Flexner and Clark (and Howard and Clark), who fed
+house-flies on emulsion of infected spinal cord, were under conditions
+so different from what could occur in nature that one could not
+draw precise conclusions from them regarding the epidemiology of
+the disease. They cited the experiments of Josefson (1912), as
+being under more reasonable conditions. He sought to determine
+whether the inoculation of monkeys with flies caught in the wards of
+the Hospital for Contagious Diseases at Stockholm, where they had
+been in contact with cases of poliomyelitis, would produce the
+disease. The results were completely negative.</p>
+
+<p>Kling and Lavaditi made four attempts of this kind. The flies
+were collected in places where poliomyelitics had dwelt, three, four
+and twenty-four after the beginning of the disease in the family and
+one, three, and fifteen days after the patient had left the house.
+These insects were for the greater part living and had certainly been
+in contact with the infected person. In addition, flies were used
+which had been caught in the wards of the Hospital for Contagious
+Diseases at Söderkoping, when numbers of poliomyelitics were confined
+there. Finally, to make the conditions as favorable as possible,
+the emulsions prepared from these flies were injected without previous
+filtering, since filtration often causes a weakening of the virus. In<span class="pagenum"><a name="Page_245" id="Page_245">[Pg 245]</a></span>
+spite of these precautions, all their results were negative, none of the
+inoculated animals having contracted poliomyelitis. They also
+experimented with bedbugs which had fed upon infected patients at
+various stages of the disease, but the results in these cases also were
+wholly negative.</p>
+
+<p>Kling and Levaditi considered at length the possibility of transmission
+of the disease by <i>Stomoxys</i>. As a result of their epidemiological
+studies, they found that infantile paralysis continued to spread
+in epidemic form in the dead of winter, when these flies were very
+rare and torpid, or were even completely absent. Numerous cases
+developed in the northern part of Sweden late in October and
+November, long after snow had fallen. On account of the rarity
+of the Stomoxys flies during the period of their investigations they
+were unable to conduct satisfactory experiments. In one instance,
+during a severe epidemic, they found a number of the flies in a stable
+near a house inhabited by an infected family, though none was
+found in the house itself. These flies were used in preparing an
+emulsion which, after filtering, was injected into the peritoneal
+cavity of a monkey. The result was wholly negative.</p>
+
+<p>As for the earlier experiments, Kling and Levaditi believe if the
+flies were responsible for the transmission of the disease in the cases
+reported by Rosenau and Brues, and the first experiments of Anderson
+and Frost, it was because the virus of infantile paralysis is eliminated
+with the nasal secretions of paralyzed monkeys and the flies,
+becoming contaminated, had merely acted as accidental carriers.</p>
+
+<p>Still further evidence against the hypothesis of the transmission
+of acute anterior poliomyelitis by <i>Stomoxys calcitrans</i> was brought
+forward by Sawyer and Herms (1913). Special precautions were
+used to prevent the transference of saliva or other possibly infectious
+material from the surface of one monkey to that of another, and to
+avoid the possibility of complicating the experiments by introducing
+other pathogenic organisms from wild flies, only laboratory-bred
+flies were used. In a series of seven carefully performed experiments,
+in which the conditions were varied, Sawyer and Herms were
+unable to transmit poliomyelitis from monkey to monkey through
+the agency of <i>Stomoxys</i>, or to obtain any indication that the fly is the
+usual agent for spreading the disease in nature.</p>
+
+<p>The evidence at hand to date indicates that acute anterior poliomyelitis,
+or infantile paralysis, is transmitted by contact with infected
+persons. Under certain conditions insects may be agents in
+spreading the disease, but their rôle is a subordinate one.<span class="pagenum"><a name="Page_246" id="Page_246">[Pg 246]</a></span></p>
+
+
+<h3><a name="Pellagra" id="Pellagra"></a>Pellagra</h3>
+
+<p><b>Pellagra</b> is an endemic and epidemic disease characterized by a
+peculiar eruption or erythema of the skin (figs&nbsp;<a href="#Fig_144">144</a> and&nbsp;<a href="#Fig_145">145</a>), digestive
+disturbances and nervous trouble.
+Insanity is a common result, rather
+than a precursor of the disease.
+The manifestations of pellagra are
+periodic and its duration indeterminate.</p>
+
+<div class="figleft" style="width: 350px;"><a name="Fig_144" id="Fig_144"></a>
+<a href="images/f144-full.png"><img src="images/f144.png" width="350" height="540" alt="144. Pellagrous eruption on the face.
+After Watson." title="144. Pellagrous eruption on the face.
+After Watson." /></a>
+<span class="caption">144. Pellagrous eruption on the face.
+After Watson.</span>
+</div>
+
+<p>The disease is one the very name
+of which was almost unknown in the
+United States until within the past
+decade. It has usually been regarded
+as tropical, though it occurs commonly
+in Italy and in various parts of Europe.
+Now it is known that it not only
+occurs quite generally in the United
+States but that it is spreading. Lavinder
+(1911) says that "There are
+certainly many thousand cases of the
+disease in this country, and the present
+situation must be looked upon
+with grave concern."</p>
+
+<p>It is not within the scope of this book to undertake a general
+discussion of pellagra. The subject is of such importance to every
+medical man that we cannot do better than refer to Lavinder's
+valuable précis. We can only touch briefly upon the entomological
+phases of the problems presented.</p>
+
+<p>The most commonly accepted theories regarding the etiology
+of the disease have attributed it to the use of Indian corn as an article
+of diet. This supposed relationship was explained either on the
+basis of, (a) insufficiency of nutriment and inappropriateness of
+corn as a prime article of food; (b) toxicity of corn or, (c) parasitism
+of certain organisms&mdash;fungi or bacteria&mdash;ingested with either sound
+or deteriorated corn.</p>
+
+<p>In 1905, Sambon proposed the theory of the protozoal origin of
+pellagra and in 1910 he marshalled an imposing array of objections
+to the theory that there existed any relationship between corn and
+the disease. He presented clear evidence that pellagra existed in
+Europe before the introduction of Indian corn from America, as an<span class="pagenum"><a name="Page_247" id="Page_247">[Pg 247]</a></span>
+article of diet, and that its spread was not <i>pari passu</i> with that of the
+use of corn. Cases were found in which the patients had apparently
+never used corn, though that is obviously difficult to establish. He
+showed that preventive measures based on the theory had been a
+failure. Finally, he believed that the recurrence of symptoms of
+the disease for successive springs, in patients who abstained absolutely
+from the use of corn, militated against the theory.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_145" id="Fig_145"></a>
+<a href="images/f145-full.png"><img src="images/f145.png" width="500" height="340" alt="145. Pellagrous eruption on the hand. After Watson." title="145. Pellagrous eruption on the hand. After Watson." /></a>
+<span class="caption">145. Pellagrous eruption on the hand. After Watson.</span>
+</div>
+
+<p>On the other hand, Sambon believed that the periodicity of the
+symptoms, peculiarities of distribution and seasonal incidence, and
+analogies of the symptoms to those of other parasitic diseases indicated
+that pellagra was of protozoal origin, and that it was insect-borne.</p>
+
+<p>The insect carriers, he believed to be one or more species of
+Simuliidæ, or black-flies. In support of this he stated that <i>Simulium</i>
+appears to effect the same topographical conditions as pellagra,
+that in its imago stage it seems to present the same seasonal incidence,
+that it has a wide geographical distribution which seems to cover
+that of pellagra, and that species of the genus are known to cause
+severe epizootics. Concluding from his studies in Italy, that pellagra
+was limited almost wholly to agricultural laborers, he pointed
+out that the Simulium flies are found only in rural districts, and as a
+rule do not enter towns, villages, or houses.</p>
+
+<div class="figcenter" style="width: 250px;">
+<a href="images/f146-full.png"><img src="images/f146.png" width="250" height="367" alt="146. A favorite breeding place of Simulium. Ithaca, N. Y." title="146. A favorite breeding place of Simulium. Ithaca, N. Y." /></a>
+<span class="caption">146. A favorite breeding place of Simulium. Ithaca, N. Y.</span>
+<span class="pagenum"><a name="Page_248" id="Page_248">[Pg 248]</a></span></div>
+
+<p>When Sambon's detailed report was published in 1910, his theory
+was seized upon everywhere by workers who were anxious to test it<span class="pagenum"><a name="Page_249" id="Page_249">[Pg 249]</a></span>
+and who, in most cases, were favorably disposed towards it because
+of the wonderful progress which had been made in the understanding
+of other insect-borne diseases. In this country, the entomological
+aspects of the subject have been dealt with especially by Forbes
+(1912), and by King and Jennings, under the direction of W. D.
+Hunter, of the Bureau of Entomology, and in coöperation with
+the Thompson-McFadden Pellagra Commission of the Department
+of Tropical Medicine of the New York Post-Graduate Medical
+School. An important series of experiments with monkeys has
+been undertaken by S. J. Hunter, of Kansas, but unfortunately we have
+as yet no satisfactory evidence that these animals are susceptible
+to the disease&mdash;a fact which renders the whole problem difficult.</p>
+
+<p>The accumulated evidence is increasingly opposed to Sambon's
+hypothesis of the transmission of pellagra by <i>Simulium</i>. This has
+been so clearly manifested in the work of the Thompson-McFadden
+Commission that we quote here from the report by Jennings (1914):</p>
+
+<p>"Our studies in 1912 convinced us that there was little evidence
+to support the incrimination of any species of <i>Simulium</i> in South
+Carolina in the transmission of pellagra. Reviewing the group as a
+whole, we find that its species are essentially "wild" and lack those
+habits of intimate association with man which would be expected
+in the vector of such a disease as pellagra. Although these flies are
+excessively abundant in some parts of their range and are moderately
+so in Spartanburg County, man is merely an incidental host, and no
+disposition whatever to seek him out or to invade his domicile seems
+to be manifested. Critically considered, it is nearer the fact that
+usually man is attacked only when he invades their habitat."</p>
+
+<p>"As our knowledge of pellagra accumulates, it is more and more
+evident that its origin is in some way closely associated with the
+domicile. The possibility that an insect whose association with man
+and his immediate environment is, at the best, casual and desultory,
+can be active in the causation of the disease becomes increasingly
+remote."</p>
+
+<p>"Our knowledge of the biting habits of <i>Simulium</i> is not complete,
+but it is evident, as regards American species at least, that these are
+sometimes not constant for the same species in different localities.
+Certain species will bite man freely when opportunity offers, while
+others have never been known to attack him. To assume that the
+proximity of a <i>Simulium</i>-breeding stream necessarily implies that
+persons in its vicinity must be attacked and bitten is highly fallacious.<span class="pagenum"><a name="Page_250" id="Page_250">[Pg 250]</a></span>
+In Spartanburg County attacks by <i>Simulium</i> seems to be
+confined to the immediate vicinity of the breeding-places. Our
+records and observations, exceedingly few in number, refer almost
+exclusively to such locations. Statements regarding such attacks,
+secured with much care and discrimination from a large number of
+persons, including many pellagrins, indicate conclusively that these
+insects are seldom a pest of man in this county. A certain number
+of the persons questioned were familiar with the gnats in other
+localities, but the majority were seemingly ignorant of the existence
+of such flies with biting habits. This is especially striking, in view
+of the fact that the average distance of streams from the homes of
+the pellagra cases studied was about 200 yards, many being at a
+distance of less than 200 yards, and that 78 per cent of these streams
+were found to be infested by larval <i>Simulium</i>. Such ignorance in a
+large number of persons cannot be overlooked and indicates strongly
+that our belief in the negligible character of local attacks by <i>Simulium</i>
+is well founded."</p>
+
+<p>"In localities infested by 'sand-flies,' mosquitoes, etc., these
+pests are always well known and the ignorance described above is
+very significant."</p>
+
+<p>"Such positive reports as we received nearly always referred to
+bites received in the open, along streams, etc., and observations made
+of their attack were of those on field laborers in similar situations.
+Males engaged in agricultural pursuits are almost exempt from
+pellagra in Spartanburg County. During the season of 1913, in
+some two or three instances, observations were made of the biting
+of <i>Simulium</i> and some additional and entirely creditable reports
+were received. These observations and reports were under conditions
+identical with those referred to in the reports of 1912 and confirm
+the conclusions based on the observations of that year. I
+would repeat with emphasis that it is inconceivable that a fly of the
+appearance and habits of the prevalent species of <i>Simulium</i> could be
+present in such a region, especially about the haunts of man and
+attack him with sufficient frequency and regularity to satisfactorily
+account for so active and prevalent a disease as pellagra without
+being a well-known and recognized pest."</p>
+
+<p>"In connection with the conditions in the Piedmont region of
+South Carolina, it may be well to cite the results of a study of those
+in the arid region of western Texas."<span class="pagenum"><a name="Page_251" id="Page_251">[Pg 251]</a></span></p>
+
+<p>"In May, 1913, in company with Capt. J. F. Siler of the Thompson-McFadden
+Pellagra Commission, I visited the region of which
+Midland in Midland County is the center. This region is very dry
+and totally devoid of running water for a long distance in every
+direction. The only natural source of water-supply, a few water
+holes and ponds, were visited and found to be of such a nature that
+the survival of <i>Simulium</i>, far less its propagation in them, is absolutely
+impossible. The nearest stream affording possibilities as a
+source of <i>Simulium</i> is 60 miles away, while the average distance of
+such possibility is not less than 100 miles."</p>
+
+<p>"Artificial sources of water-supply were also investigated carefully
+and were found to offer no opportunity for the breeding of
+<i>Simulium</i>."</p>
+
+<p>"At Midland the histories of five cases of pellagra were obtained,
+which gave clear evidence that this place or its immediate vicinity
+was the point of origin. Persons of long residence in the country
+were questioned as to the occurrence of such flies as <i>Simulium</i> and
+returned negative answers. These included a retired cattle owner,
+who is a man of education and a keen observer, an expert veterinarian
+stationed in the country who has the cattle of the country under
+constant observation, and a practical cattle man, manager of a ranch
+and of wide experience. The latter had had experience with 'Buffalo
+gnats' in other localities (in the East) and is well acquainted
+with them. His close personal supervision of the cattle under his
+charge, makes it practically certain that he would have discovered
+these gnats had they been present in the country."</p>
+
+<p>"At the time the study was made, <i>Simulium</i> was breeding and
+active in the adult state in the vicinity of Dallas, Texas, in the
+eastern part of the state. We have here a region in which cases of
+pellagra have originated, yet in which <i>Simulium</i> does not and cannot
+breed."</p>
+
+<p>Other possible insect vectors of pellagra have been studied in
+great detail and the available evidence indicates that if <i>any</i> insect
+plays a rôle in the spread of the disease, <i>Stomoxys calcitrans</i> most
+nearly fills the conditions. This conclusion was announced by
+Jennings and King in 1912, and has been supported by their subsequent
+work.</p>
+
+<p>Yet, after all the studies of the past decade, the old belief that
+pellagra is essentially of dietary origin is gaining ground. Goldberger,
+Waring and Willets (1914) of the United States Public Health<span class="pagenum"><a name="Page_252" id="Page_252">[Pg 252]</a></span>
+Service summarize their conclusions in the statement, (1) that it is
+dependent on some yet undetermined fault in a diet in which the
+animal or leguminous protein component is disproportionately large
+and (2) that no pellagra develops in those who <i>consume</i> a mixed,
+well-balanced, and varied diet, such, for example, as that furnished
+by the Government to the enlisted men of the Army, Navy, and
+Marine Corps.</p>
+
+
+<h3><a name="Leprosy" id="Leprosy"></a>Leprosy</h3>
+
+<p><b>Leprosy</b> is a specific, infectious disease due to <i>Bacillus lepræ</i>, and
+characterized by the formation of tubercular nodules, ulcerations,
+and disturbances of sensation. In spite of the long time that the
+disease has been known and the dread with which it is regarded,
+little is known concerning the method of transfer of the causative
+organism or the means by which it gains access to the human body.</p>
+
+<p>It is known that the bacilli are to be found in the tubercles, the
+scurf of the skin, nasal secretions, the sputum and, in fact in practically
+all the discharges of the leper. Under such conditions it is
+quite conceivable that they may be transferred in some instances
+from diseased to healthy individuals through the agency of insects
+and other arthropods. Many attempts have been made to demonstrate
+this method of spread of the disease, but with little success.</p>
+
+<p>Of the suggested insect carriers none seem to meet the conditions
+better than mosquitoes, and there are many suggestions in literature
+that these insects play an important rôle in the transmission of
+leprosy. The literature has been reviewed and important experimental
+evidence presented by Currie (1910). He found that mosquitoes
+feeding, under natural conditions, upon cases of nodular leprosy
+so rarely, if ever, imbibe the lepra bacillus that they cannot be
+regarded as one of the ordinary means of transference of this bacillus
+from lepers to the skin of healthy persons. He believes that the
+reason that mosquitoes that have fed on lepers do not contain the
+lepra bacillus is that when these insects feed they insert their proboscis
+directly into a blood vessel and thus obtain bacilli-free blood,
+unmixed with lymph.</p>
+
+<p>The same worker undertook to determine whether flies are able
+to transmit leprosy. He experimented with five species found in
+Honolulu,&mdash;<i>Musca domestica</i>, <i>Sarcophaga pallinervis</i>, <i>Sarcophaga
+barbata</i>, <i>Volucella obesa</i> and an undetermined species of <i>Lucilia</i>.
+The experiments with <i>Musca domestica</i> were the most detailed.<span class="pagenum"><a name="Page_253" id="Page_253">[Pg 253]</a></span>
+From these experiments he concluded, first, that all of the above-named
+flies, when given an opportunity to feed upon leprous fluids,
+will contain the bacilli in their intestinal tracts and feces for several
+days after such feeding. Second, that considering the habits of
+these flies, and especially those of <i>Musca domestica</i>, it is certain that,
+given an exposed leprous ulcer, these insects will frequently convey
+immense numbers of lepra bacilli, directly or indirectly, to the skins,
+nasal mucosa, and digestive tracts of healthy persons. Additional
+evidence along this line has recently been brought forward by
+Honeij and Parker (1914), who incriminate both <i>Musca domestica</i>
+and <i>Stomoxys calcitrans</i>. Whether or not such insect-borne bacilli
+are capable of infecting persons whose skin and mucosa are thus
+contaminated, Currie was unwilling to maintain, but he concludes
+that until we have more accurate knowledge on this point, we are
+justified in regarding these insects with grave suspicion of being
+one of the means of disseminating leprous infection.</p>
+
+<p>Various students of the subject have suggested that bed-bugs
+may be the carriers of leprosy and have determined the presence of
+acid-fast bacilli in the intestines of bed-bugs which had fed on leprous
+patients. Opposed to this, the careful experiments of Thompson
+(1913) and of Skelton and Parkham (1913) have been wholly negative.</p>
+
+<p>Borrel has recently suggested that <i>Demodex</i>, may play a rôle in
+spreading the infection in families. Many other insects and acariens
+have been suggested as possible vectors, but the experimental data
+are few and in no wise conclusive. The most that can be said is that
+it is quite possible that under favorable conditions the infection
+might be spread by any of the several blood-sucking forms or by
+house-flies.</p>
+
+
+<h3><a name="Verruga_peruviana" id="Verruga_peruviana"></a>Verruga peruviana</h3>
+
+<p><b>Verruga peruviana</b> is defined by Castellani and Chalmers as "a
+chronic, endemic, specific, general disorder of unknown origin, not
+contagious, but apparently inoculable, and characterized by an irregular
+fever associated with rheumatoid pains, anemia, followed
+by granulomatous swellings in the skin, mucous membranes, and
+organs of the body." It has been generally believed by medical
+men interested that the comparatively benign eruptive verruga is
+identical with the so-called Oroya, or Carrion's fever, a malignant
+type. This view is not supported by the work of Strong, Tyzzer
+and Brues, (1913).<span class="pagenum"><a name="Page_254" id="Page_254">[Pg 254]</a></span></p>
+
+<p>The disease is confined to South America and to definitely limited
+areas of those countries in which it does occur. It is especially
+prevalent in some parts of Peru.</p>
+
+<p>The causative organism and the method of transfer of verruga
+are unknown. Castellani and Chalmers pointed out in 1910 that the
+study of the distribution of the disease in Peru would impress one
+with the similarity to the distribution of the Rocky Mountain fever
+and would lead to the conclusion that the ætiological cause must in
+some way be associated with some blood-sucking animal, perhaps an
+arachnid, and that this is supported by the fact that the persons
+most prone to the infection are those who work in the fields.</p>
+
+<p>More recently, Townsend (1913), in a series of papers, has maintained
+that verruga and Carrion's disease are identical, and that they
+are transmitted to man by the bites of the Psychodid fly, <i>Phlebotomus
+verrucarum</i>. He succeeded in producing the eruptive type of the
+disease in experimental animals by injecting a physiological salt
+trituration of wild Phlebotomus flies. A cebus monkey was exposed
+from October so to November 6, by chaining him to a tree in the
+verruga zone, next to a stone wall from which the flies emerged in
+large numbers every night. Miliar eruption began to appear on the
+orbits November 13 and by November 21, there were a number of
+typical eruptions, with exudation on various parts of the body
+exactly like miliar eruptive sores commonly seen on legs of human
+cases.</p>
+
+<p>An assistant in the verruga work, George E. Nicholson, contracted
+the eruptive type of the disease, apparently as a result of being bitten
+by the Phlebotomus flies. He had slept in a verruga zone, under a
+tight net. During the night he evidently put his hands in contact
+with the net, for in the morning there were fifty-five unmistakable
+Phlebotomus bites on the backs of his hands and wrists.</p>
+
+<p>Townsend believes that in nature, lizards constitute the reservoir
+of the disease and that it is from them that the Phlebotomus flies
+receive the infection.</p>
+
+
+<h3><a name="Cancer" id="Cancer"></a>Cancer</h3>
+
+<p>There are not wanting suggestions that this dread disease is
+carried, or even caused, by arthropods. Borrel (1909) stated that
+he had found mites of the genus <i>Demodex</i> in carcinoma of the face
+and of the mammæ. He believed that they acted as carriers of the
+virus.<span class="pagenum"><a name="Page_255" id="Page_255">[Pg 255]</a></span></p>
+
+<p>Saul (1910) and Dahl (1910) go much further, since they attribute
+the production of the malignant growth to the presence of mites
+which Saul had found in cancers. These Dahl described as belonging
+to a new species, which he designated <i>Tarsonemus hominis</i>. These
+findings have since been confirmed by several workers. Nevertheless,
+the presence of the mite is so rare that it cannot be regarded as
+an important factor in the causation of the disease. The theory
+that cancer is caused by an external parasite is given little credence
+by investigators in this field.</p>
+
+
+<p><b>In conclusion</b>, it should be noted that the medical and entomological
+literature of the past few years abounds in suggestions, and in
+unsupported direct statements that various other diseases are insect-borne.
+Knab (1912) has well said "Since the discovery that certain
+blood-sucking insects are the secondary hosts of pathogenic parasites,
+nearly every insect that sucks blood, whether habitually or
+occasionally, has been suspected or considered a possible transmitter
+of disease. No thought seems to have been given to the conditions
+and the characteristics of the individual species of blood-sucking
+insects, which make disease transmission possible."</p>
+
+<p>He points out that "in order to be a potential transmitter of human
+blood-parasites, an insect must be closely associated with man and
+normally have opportunity to suck his blood repeatedly. It is not
+sufficient that occasional specimens bite man, as, for example, is the
+case with forest mosquitoes. Although a person may be bitten by a
+large number of such mosquitoes, the chances that any of these
+mosquitoes survive to develop the parasites in question, (assuming
+such development to be possible), and then find opportunity to bite
+and infect another person, are altogether too remote. Applying
+this criterion, not only the majority of mosquitoes but many other
+blood-sucking insects, such as Tabanidæ and Simuliidæ, may be
+confidently eliminated. Moreover, these insects are mostly in
+evidence only during a brief season, so that we have an additional
+difficulty of a very long interval during which there could be no propagation
+of the disease in question." He makes an exception of
+tick-borne diseases, where the parasites are directly transmitted from
+the tick host to its offspring and where, for this reason, the insect
+remains a potential transmitter for a very long period. He also
+cites the trypanosome diseases as possible exceptions, since the causative
+organisms apparently thrive in a number of different vertebrate
+hosts and may be transmitted from cattle, or wild animals, to man.<span class="pagenum"><a name="Page_256" id="Page_256">[Pg 256]</a></span></p>
+
+<p>Knab's article should serve a valuable end in checking irresponsible
+theorizing on the subject of insect transmission of disease.
+Nevertheless, the principles which he laid down cannot be applied
+to the cases of accidental carriage of bacterial diseases, or to those
+of direct inoculation of pyogenic organisms, or of blood parasites
+such as the bacillus of anthrax, or of bubonic plague. Accumulated
+evidence has justified the conclusion that certain trypanosomes
+pathogenic to man are harbored by wild mammals, and so form an
+exception. Townsend believes that lizards constitute the natural
+reservoir of verruga; and it seems probable that field mice harbor
+the organism of tsutsugamushi disease. Such instances are likely to
+accumulate as our knowledge of the relation of arthropods to disease
+broadens.<span class="pagenum"><a name="Page_257" id="Page_257">[Pg 257]</a></span></p>
+
+
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="CHAPTER_XII" id="CHAPTER_XII"></a>CHAPTER XII</h2>
+
+<h2>HOMINOXIOUS ARTHROPODS</h2>
+
+
+<p>The following synoptic tables are presented in the hope that they
+may be of service in giving the reader a perspective of the relationships
+of the Arthropoda in general and enabling him to identify the
+more important species which have been found noxious to man.
+Though applicable chiefly to the arthropods found in the United
+States, exotic genera and species which are concerned in the transmission
+of disease are also included. For this reason the keys to the
+genera of the Muscids of the world are given. As will be seen, the
+tables embrace a number of groups of species which are not injurious.
+This was found necessary in order that the student might not be
+lead to an erroneous determination which would result were he to
+attempt to identify a species which heretofore had not been considered
+noxious, by means of a key containing only the noxious forms. The
+names printed in <b>bold faced type</b> indicate the hominoxious arthropods
+which have been most commonly mentioned in literature.</p>
+
+
+<h3><a name="CRUSTACEA" id="CRUSTACEA"></a>CRUSTACEA</h3>
+
+<p>Arthropods having two pairs of antennæ which are sometimes
+modified for grasping, and usually with more than five pairs of legs.
+With but few exceptions they are aquatic creatures. Representatives
+are: Crabs, lobsters, shrimps, crayfish, water-fleas, and woodlice.
+To this class belongs the <b>Cyclops</b> (<a href="#Fig_122">fig.&nbsp;122</a>) a genus of minute aquatic
+crustaceans of which at least one species harbors <i>Dracunculus medinensis</i>,
+the Guinea worm (<a href="#Fig_121">fig.&nbsp;121</a>).</p>
+
+
+<h3><a name="MYRIAPODA_1" id="MYRIAPODA_1"></a>MYRIAPODA</h3>
+
+<p>Elongate, usually vermiform, wingless, terrestrial creatures having
+one pair of antennæ, legs attached to each of the many intermediate
+body segments. This group is divided into two sections, now usually
+given class rank: the <b>Diplopoda</b> or millipedes (<a href="#Fig_13">fig.&nbsp;13</a>), commonly
+known as thousand legs, characterized by having two pairs of legs
+attached to each intermediate body segment, and the <b>Chilopoda</b>
+or centipedes (<a href="#Fig_14">fig.&nbsp;14</a>) having only one pair of legs to each body segment.<span class="pagenum"><a name="Page_258" id="Page_258">[Pg 258]</a></span></p>
+
+
+<h3>ARACHNIDA</h3>
+
+<p>In this class the antennæ are apparently wanting, wings are never
+present, and the adults are usually provided with four pairs of legs.
+Scorpions, harvest-men, spiders, mites, etc.</p>
+
+
+<h3>HEXAPODA (Insects)</h3>
+
+<p>True insects have a single pair of antennæ, which is rarely vestigial,
+and usually one or two pairs of wings in the adult stage. Familiar
+examples are cockroaches, crickets, grasshoppers, bugs, dragon-flies,
+butterflies, moths, mosquitoes, flies, beetles, ants, bees and wasps.</p>
+
+
+<h3><a name="ORDERS_OF_THE_ARACHNIDA" id="ORDERS_OF_THE_ARACHNIDA"></a>ORDERS OF THE ARACHNIDA</h3>
+
+<div class="hanging">
+<p>a. Abdomen distinctly segmented. A group of orders including scorpions,
+(<a href="#Fig_11">fig.&nbsp;11</a>), whip-scorpions (<a href="#Fig_10">fig.&nbsp;10</a>), pseudo-scorpions, solpugids (<a href="#Fig_12">fig.&nbsp;12</a>)
+harvest-men (daddy-long-legs or harvestmen), etc. <span class="rightalign"><b>Arthrogastra</b></span></p>
+
+<p>aa. Abdomen unsegmented, though sometimes with numerous annulations
+<span class="rightalign"><b>Sphærogastra</b></span></p>
+
+<div class="hanging">
+<p>b. A constriction between cephalothorax and abdomen (<a href="#Fig_7">fig.&nbsp;7</a>). True Spiders
+<span class="rightalign"><b>Araneida</b></span></p>
+
+<p>bb. No deep constriction between these parts.</p>
+
+<div class="hanging">
+<p>c. Legs usually well developed, body more or less depressed (<a href="#Fig_49">fig.&nbsp;49</a>). Mites
+<span class="rightalign"><b>Acarina</b></span></p>
+
+<p>cc. Legs stumpy or absent, body more or less elongate or vermiform, or if
+shorter, the species is aquatic or semi-aquatic in habit.</p>
+
+<div class="hanging">
+<p>d. Four pairs of short legs; species inhabiting moss or water. Water-bears.
+<span class="rightalign"><b>Tardigrada</b></span></p>
+
+<p>dd. Two pairs of clasping organs near the mouth, instead of legs, in the
+adult; worm-like creatures parasitic within the nasal passages,
+lungs, etc. of mammals and reptiles (<a href="#Fig_148">fig.&nbsp;148</a>). Tongue worms.
+<span class="rightalign"><b>Linguatulina</b></span></p>
+</div></div></div></div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_148" id="Fig_148"></a>
+<a href="images/f148-full.png"><img src="images/f148.png" width="500" height="229" alt="148. Linguatula. (a) larva; (enlarged). (b) adult; (natural size)." title="148. Linguatula. (a) larva; (enlarged). (b) adult; (natural size)." /></a>
+<span class="caption">148. Linguatula. (<i>a</i>)&nbsp;larva; (enlarged). (<i>b</i>)&nbsp;adult; (natural size).</span>
+</div><p><span class="pagenum"><a name="Page_259" id="Page_259">[Pg 259]</a></span></p>
+
+
+<h3><a name="ACARINA_KEY" id="ACARINA_KEY"></a>ACARINA<a name="FNanchor_E_5" id="FNanchor_E_5"></a><a href="#Footnote_E_5" class="fnanchor">[E]</a></h3>
+
+<div class="hanging">
+<p>a. Abdomen annulate, elongate; very minute forms, often with but four legs
+(<a href="#Fig_62">fig.&nbsp;62</a>). <span class="rightalign"><span class="smcap"><b>Demodicoidea</b></span></span></p>
+
+<div class="hanging">
+<p>b. With but four legs of five segments each. Living on plants, often forming
+galls. <span class="rightalign"><span class="smcap"><b>Eriophyidæ</b></span></span></p>
+
+<p>bb. With eight legs, of three segments each. Living in the skin of mammals.
+<span class="rightalign"><span class="smcap"><b>Demodicidæ</b></span></span></p>
+
+<div class="hanging">
+<p>To this family belongs the genus <b>Demodex</b> found in the sebaceous glands
+and hair follicles of various mammals, including man. <i>D. phylloides</i>
+Csokor has been found in Canada on swine, causing white tubercles
+on the skin. <i>D. bovis</i> Stiles has been reported from the United States
+on cattle, upon the skin of which they form swellings. <b>D. folliculorum</b>
+Simon is the species found on man. See <a href="#Page_78">page 78</a>.</p>
+</div></div>
+
+<p>aa. Abdomen not annulate nor prolonged behind; eight legs in the adult stage.</p>
+
+<div class="hanging">
+<p>b. With a distinct spiracle upon a stigmal plate on each side of the body (usually
+ventral) above the third or fourth coxæ or a little behind (<a href="#Fig_50">fig.&nbsp;50</a>);
+palpi free; skin often coriaceous or leathery; tarsi often with a sucker.</p>
+
+<div class="hanging">
+<p>c. Hypostome large (<a href="#Fig_50">fig.&nbsp;50</a>), furnished below with many recurved teeth;
+venter with furrows, skin leathery; large forms, usually parasitic.
+<span class="rightalign"><span class="smcap"><b>Ixodoidea</b></span></span></p>
+
+<div class="hanging">
+<p>d. Without scutum but covered by a more or less uniform leathery integument;
+festoons absent; coxæ unarmed, tarsi without ventral spurs;
+pulvilli absent or vestigial in the adults; palpi cylindrical; sexual
+dimorphism slight. <span class="rightalign"><span class="smcap"><b>Argasidæ</b></span></span></p>
+
+<div class="hanging">
+<p>e. Body flattened, oval or rounded, with a distinct flattened margin
+differing in structure from the general integument; this margin
+gives the body a sharp edge which is not entirely obliterated even
+when the tick is full fed. Capitulum (in adults and nymphs)
+entirely invisible dorsally, distant in the adult by about its own
+length from the anterior border. Eyes absent. <span class="rightalign"><b>Argus</b> Latr.</span></p>
+
+<div class="hanging">
+<p>f. Body oblong; margin with quadrangular cells; anterior tibiæ and
+metatarsi each about three times as long as broad. On poultry,
+southwest United States. <span class="rightalign"><b>A. persicus miniatus</b></span></p>
+
+<div class="hanging">
+<p><i>A. brevipes</i> Banks, a species with proportionately shorter legs has
+been recorded from Arizona.</p>
+</div>
+
+<p>ff. With another combination of characters. About six other species
+of <i>Argas</i> from various parts of the world, parasitic on birds and
+mammals.</p>
+</div>
+
+<p>ee. Body flattened when unfed, but usually becoming very convex on
+distention; anterior end more or less pointed and hoodlike;
+margin thick and not clearly defined, similar in structure to the
+rest of the integument and generally disappearing on distention;
+capitulum subterminal, its anterior portions often visible dorsally
+in the adult; eyes present in some species.</p>
+
+<div class="hanging">
+<p>f. Integument pitted, without rounded tubercles; body provided
+with many short stiff bristles; eyes absent. On horses, cattle
+and man (<a href="#Fig_48">fig.&nbsp;48</a>). <span class="rightalign"><b>Otiobius</b> Banks.</span></p>
+
+<div class="hanging">
+<p><b>O. megnini</b>, a widely distributed species, is the type of this genus.<span class="pagenum"><a name="Pg_260" id="Pg_260"></a>[Pg 260]</span></p>
+</div>
+
+<p>ff. Integument with rounded tubercles or granules; body without stiff
+bristles. <span class="rightalign"><b>Ornithodoros</b> Koch.</span></p>
+
+<div class="hanging">
+<p>g. Two pairs of eyes; tarsi&nbsp;IV with a prominent subterminal spur
+above; leg&nbsp;I strongly roughened. On cattle and man.
+<span class="rightalign"><b>O. coriaceus</b></span></p>
+
+<p>gg. No eyes; no such spur on the hind tarsi.</p>
+
+<div class="hanging">
+<p>h. Tarsi&nbsp;I without humps above. <span class="rightalign"><i>O. talaje.</i></span></p>
+
+<p>hh. Tarsi&nbsp;I with humps above.</p>
+
+<div class="hanging">
+<p>i. Tarsi&nbsp;IV without distinct humps above. On hogs, cattle
+and man. <span class="rightalign"><b>O. turicata</b></span></p>
+
+<p>ii. Tarsi&nbsp;IV with humps nearly equidistant (<a href="#Fig_142">fig.&nbsp;142</a>). Africa.
+<span class="rightalign"><b>O. moubata</b></span></p>
+</div></div></div></div></div>
+
+<p>dd. With scutum or shield (<a href="#Fig_50">fig.&nbsp;50</a>); festoons usually present; coxæ
+usually armed with spurs, tarsi generally with one or two ventral
+spurs; pulvilli present in the adults; sexual dimorphism pronounced.
+<span class="rightalign"><span class="smcap"><b>Ixodidæ</b></span></span></p>
+
+<div class="hanging">
+<p>e. With anal grooves surrounding anus in front; inornate; without eyes;
+no posterior marginal festoons; venter of the male with non-salient
+plates. Numerous species, 14 from the United States,
+among them <b>I.&nbsp;ricinus</b> (fig.&nbsp;<a href="#Fig_49">49</a> and&nbsp;<a href="#Fig_50">50</a>), <b>scapularis</b>, <b>cookei</b>, <i>hexagonus</i>,
+<i>bicornis</i>. <span class="rightalign"><b>Ixodes</b> Latr. (including Ceratixodes).</span></p>
+
+<p>ee. With anal groove contouring anus behind, or groove faint or obsolete.</p>
+
+<div class="hanging">
+<p>f. With short palpi (<a href="#Fig_149">fig.&nbsp;149</a>).</p>
+
+<div class="hanging">
+<p>g. Without eyes, inornate, with posterior marginal festoons; male
+without ventral plates. Numerous species. <i>H. chordeilis</i>
+and <i>leporis-palustris</i> from the United States.
+<span class="rightalign"><i>Hæmaphysalis</i> Koch.</span><span class="pagenum"><a name="Page_262" id="Page_262">[Pg 262]</a></span></p>
+
+<p>gg. With eyes.</p>
+
+<div class="hanging">
+<p>h. Anal groove distinct; posterior marginal festoons present.</p>
+
+<div class="hanging">
+<p>i. Base of the capitulum (<a href="#Fig_150">fig.&nbsp;150c</a>) rectangular dorsally;
+usually ornate.&nbsp;<span class="rightalign"><b>Dermacentor</b> Koch.</span></p>
+
+<div class="hanging">
+<p>j. Adults with four longitudinal rows of large denticles on
+each half of hypostome; stigmal plate nearly circular,
+without dorso-lateral prolongation, goblets very large,
+attaining 43µ to 115µ in diameter; not over 40 per
+plate, each plate surrounded by an elevated row of
+regularly arranged supporting cells; white rust wanting;
+base of capitulum distinctly broader than long,
+its postero-lateral angles prolonged slightly, if at all;
+coxæ T with short spurs; trochanter&nbsp;I with small
+dorso-terminal blade. Texas, Arizona, etc. <span class="rightalign"><i>D. nitens</i></span></p>
+
+<p>jj. Adults with three longitudinal rows of large denticles on
+each half of hypostome; goblet cells always more
+than 40 per plate; whitish rust usually present.</p>
+
+<div class="hanging">
+<p>k. Dorso-lateral prolongation of stigmal plate small or
+absent; plates of the adults distinctly longer than
+broad; goblet cells large, usually 30µ to 85µ in
+diameter, appearing as very coarse punctations on
+untreated specimens, but on specimens treated
+with caustic potash they appear very distinct in
+outline; base of capitulum distinctly (usually about
+twice) broader than long, the postero-lateral angles
+distinctly produced caudad; spurs of coxæ&nbsp;I long,
+lateral spur slightly longer than median; trochanter
+I with dorso-terminal spur. <i>D. albipictus</i>,
+(=&nbsp;<i>variegatus</i>), <i>salmoni</i>, <i>nigrolineatus</i>.<span class="pagenum"><a name="Page_263" id="Page_263"></a>[Pg 263]</span></p>
+
+<p>kk. Dorso-lateral prolongation of stigmal plate distinct.</p>
+
+<div class="hanging">
+<p>l. Body of plate distinctly longer than broad; goblet
+cells of medium size, usually 17.5µ to 35µ or 40µ in
+diameter, appearing as medium sized punctuations
+on untreated specimens, but on the specimens
+treated with caustic potash they appear
+very distinct in outline, which is not circular;
+base of capitulum usually less than twice as broad
+as long, the postero-lateral angles always distinctly
+prolonged caudad.</p>
+
+<div class="hanging">
+<p>m. Trochanter I with distinct dorso-subterminal
+retrograde sharp, digitate spur; postero-lateral
+angles of capitulum pronouncedly
+prolonged caudal, 112µ to 160µ long; goblet
+cells attain 13µ to 40µ in diameter; type
+locality California. <span class="rightalign"><b>D. occidentalis</b></span></p>
+
+<p>mm. Trochanter I with dorso-terminal blade; postero-lateral
+angles of capitulum with rather short
+prolongations.</p>
+
+<div class="hanging">
+<p>n. Stigmal plate small, goblet cells not exceeding
+45 in the male or 100 in the female; scutum
+with little rust, coxa&nbsp;I with short spurs, the
+inner distinctly shorter than the outer.
+<span class="rightalign"><i>D. parumapertus-marginatus</i></span></p>
+
+<p>nn. Stigmal plate larger; goblet cells over 70 in
+the male and over 100 in the female; coxa&nbsp;I
+with longer spurs, inner slightly shorter
+than the outer; scutum with considerable
+rust. <span class="rightalign"><b>D. venustus</b><a name="FNanchor_F_6" id="FNanchor_F_6"></a><a href="#Footnote_F_6" class="fnanchor">[F]</a></span></p>
+</div></div>
+
+<p>ll. Goblet cells small, rarely exceeding 17.6µ, occasionally
+reaching 19µ in diameter; on untreated specimens
+they appear as very fine granulations, and on
+specimens treated with caustic potash they may
+be difficult to see, but their large number can
+be determined from the prominent stems of the
+goblets; surface of outline of the goblets distinctly
+circular; base of the capitulum usually less
+than twice as broad as long, the postero-lateral
+angle distinctly prolonged caudad; spurs of
+coxæ&nbsp;I long.
+<i>D. reticulatus</i> and <i>electus</i> (=&nbsp;<i>variabilis</i>?)</p>
+</div></div></div>
+
+<p>ii. Base of the capitulum (<a href="#Fig_151">fig.&nbsp;151</a>) usually hexagonal (except
+in the male of <i>puchellus</i>); and usually inornate.<span class="pagenum"><a name="Page_264" id="Page_264">[Pg 264]</a></span></p>
+
+<div class="hanging">
+<p>j. No ventral plate or shield in either sex (<a href="#Fig_153">fig.&nbsp;153</a>). <b>R.
+bicornis</b> from the United States. <span class="rightalign"><b>Rhipicentor</b> Nuttall</span></p>
+
+<p>jj. Males with a pair of adanal shields, and usually a pair of
+accessory adanal shields. Numerous species, among
+them <i>R. sanguineus</i> (<a href="#Fig_154">fig.&nbsp;154</a>) and <i>texanus</i>, the latter
+from the United States. <span class="rightalign"><i>Rhipicephalus</i> Koch</span></p>
+</div></div>
+
+<p>hh. Anal grooves faint or obsolete; no marginal festoons.</p>
+
+<div class="hanging">
+<p>i. Short palpi; highly chitinized; unfed adults of large size;
+coxæ conical; male with a median plate prolonged in two
+long spines projecting caudad; segments of leg pair IV
+greatly swollen (fig. <a href="#Fig_155">155</a>,&nbsp;<a href="#Fig_156">156</a>). <i>M. winthemi</i>
+<span class="rightalign"><i>Margaropus</i> Karsch</span></p>
+
+<p>ii. Very short palpi, ridged dorsally and laterally; slightly
+chitinized; unfed adults of smaller size; coxæ I bifid;
+male with adanal and accessory adanal shields (<a href="#Fig_139">fig.&nbsp;139</a>).
+<b>B. annulatus.</b> <span class="rightalign"><b>Boophilus</b> Curtis</span></p>
+</div></div></div>
+
+<p>ff. Palpi longer than broad (<a href="#Fig_157">fig.&nbsp;157</a>).</p>
+
+<div class="hanging">
+<p>g. Male with pair of adanal shields, and two posterior abdominal
+protrusions capped by chitinized points; festoons present or
+absent. Several species, among them <b>H.&nbsp;ægypticum</b> (<a href="#Fig_140">fig.&nbsp;140</a>)
+from the old world. <span class="rightalign"><b>Hyalomma</b> Koch</span></p>
+
+<p>gg. Male without adanal shields but small ventral plaques are
+occasionally present close to the festoons. Many species, a
+few from the United States (<a href="#Fig_157">fig.&nbsp;157</a>). <span class="rightalign"><b>Amblyomma</b> Koch</span></p>
+
+<div class="hanging">
+<p>h. Coxa&nbsp;I with but one spine, metatarsi (except&nbsp;I) with two
+thickened spurs at tips. <span class="rightalign"><i>A. maculatum</i></span></p>
+
+<p>hh. Coxa&nbsp;I with two spines; metatarsi without stout spurs at
+tips, only slender hairs.<span class="pagenum"><a name="Page_265" id="Page_265">[Pg 265]</a></span></p>
+
+<div class="hanging">
+<p>i. Projections of coxa&nbsp;I blunt and short. Large species on the
+gopher tortoise in Florida. <span class="rightalign"><i>A. tuberculatum</i></span></p>
+
+<p>ii. Projections of coxa&nbsp;I longer, and at least one of them sharp
+pointed; second segment of palpus twice as long as the
+third; coxa&nbsp;IV of the male with a long spine.</p>
+
+<div class="hanging">
+<p>j. Porose areas nearly circular; shield of both sexes pale
+yellowish, with some silvery streaks and marks, and
+some reddish spots; shield of female as broad as long.
+<span class="rightalign"><b>A. cajennense</b> (=&nbsp;<b>mixtum</b>).</span></p>
+
+<p>jj. Porose areas elongate, shield brown, in the female with
+an apical silvery mark, in the male with two small
+and two or four other silvery spots; shield of the female
+longer than broad (<a href="#Fig_158">fig&nbsp;158&nbsp;e</a>). <span class="rightalign"><b>A. americanum.</b></span></p>
+</div></div></div></div></div></div></div>
+
+<p>cc. Hypostome small, without teeth, venter without furrows; body often
+with coriaceous shields, posterior margin of the body never crenulate
+(i.e. without festoons); no eyes. <span class="rightalign">GAMASOIDEA.</span></p>
+
+<div class="hanging">
+<p>d. Parasitic on vertebrates; mandibles fitted for piercing; body sometimes
+constricted. <span class="rightalign"><span class="smcap">Dermanyssidæ.</span></span></p>
+
+<div class="hanging">
+<p>e. Anal plate present. <span class="rightalign"><span class="smcap">Dermanyssinæ.</span></span></p>
+
+<div class="hanging">
+<p>f. Body short; legs stout, hind pair reaching much beyond the tip of
+the body. On bats. <span class="rightalign"><i>Pteroptus</i> Dufour.</span></p>
+
+<p>ff. Body long; hind legs not reaching beyond the tip of the body.</p>
+
+<div class="hanging">
+<p>g. Peritreme on the dorsum, very short; body distinctly constricted.
+<span class="rightalign"><i>Ptilonyssus</i> Berl.</span></p>
+
+<p>gg. Peritreme on the venter, longer; body not distinctly constricted.</p>
+
+<div class="hanging">
+<p>h. Mandibles in both sexes chelate. Parasitic on bats, mice
+and birds (<a href="#Fig_150">fig.&nbsp;150, h</a>). <span class="rightalign"><b>Liponyssus</b> Kol.</span></p>
+
+<div class="hanging">
+<p>The species <b>L.</b> (=&nbsp;<b>Leiognathus</b>) <b>sylviarum</b> frequents the
+nests of warblers. An instance is on record of these mites
+attacking man, causing a pruritis.<span class="pagenum"><a name="Pg_266" id="Pg_266"></a>[Pg 266]</span></p>
+</div>
+
+<p>hh. Mandibles in the male chelate (<span title="refers to the female"><a name="AC_13" id="AC_13"></a><a href="#Fig_158">fig.&nbsp;158&nbsp;j</a></span>), in the female long,
+styliform. Parasitic on birds. <span class="rightalign"><b>Dermanyssus</b> Dug.</span></p>
+
+<div class="hanging">
+Two species of importance may be noted, <i>D. hirundinus</i>
+and <b>D. gallinæ</b>. The latter (<a href="#Fig_51">fig.&nbsp;51</a>) is a serious pest
+of poultry, sometimes attacking man, causing itching
+and soreness.
+</div></div></div></div>
+
+<p>ee. Anal plate absent. In lungs and air passages of some mammals.
+<span class="rightalign"><span class="smcap"><b>Halarachninæ.</b></span></span></p>
+</div>
+
+<p>dd. Free or attached to insects, rarely on vertebrates.</p>
+
+<div class="hanging">
+<p>e. First pair of legs inserted within the same body opening as the oral
+tube; genital apertures surrounded by the sternum. On insects.
+<span class="rightalign"><span class="smcap">Uropodidæ.</span></span></p>
+
+<p>ee. First pair of legs inserted at one side of the mouth opening; male
+genital aperture usually on the anterior margin of the sternal
+plate. <span class="rightalign"><b>Gamasidæ.</b></span></p>
+
+<div class="hanging">
+<p>This family contains a number of genera, some of which are found
+upon mammals, though the majority affect only other arthropods.
+One species, <b>Lælaps stabularis</b>, frequents the bedding
+in stables, and in one instance at least, has occasioned irritation
+and itching, in man.</p>
+</div></div></div></div>
+
+<p>bb. No distinct spiracle in the stigmal plate on each side of the body.</p>
+
+<div class="hanging">
+<p>c. Body usually coriaceous, with few hairs, with a specialized seta arising
+from a pore near each posterior corner of the cephalothorax; no eyes;
+mouth parts and palpi very small; ventral openings of the abdomen
+large; tarsi without sucker. Not parasitic. <span class="rightalign">ORIBATOIDEA.</span></p>
+
+<p>cc. Body softer; without such specialized seta.</p>
+
+<div class="hanging">
+<p>d. Aquatic species. <span class="rightalign">HYDRACHNOIDEA.</span></p>
+
+<p>dd. Not aquatic.<span class="pagenum"><a name="Page_267" id="Page_267">[Pg 267]</a></span></p>
+
+<div class="hanging">
+<p>e. Palpi small, three segmented, adhering for some distance to the lip;
+ventral suckers at genital opening or near anal opening usually
+present; no eyes; tarsi often end in suckers; beneath the skin on
+the venter are seen rod-like epimera that support the legs; body
+often entire. Adults frequently parasitic. <span class="rightalign"><b>SARCOPTOIDEA.</b></span></p>
+
+<div class="hanging">
+<p>f. With tracheæ; no ventral suckers; legs ending in claws; body
+divided into cephalothorax and abdomen; the female with a
+clavate hair between legs I and II. Usually not parasitic
+on birds and mammals. <span class="rightalign"><span class="smcap"><b>Tarsonemidæ</b></span></span></p>
+
+<div class="hanging">
+<p>g. Hind legs of female ending in claw and sucker as in the other
+pairs. <span class="rightalign"><span class="smcap"><b>Pediculoidinæ</b></span></span></p>
+
+<div class="hanging">
+<p>To this sub-family belongs the genus <span class="smcap"><b>Pediculoides</b></span></p>
+
+<p><b>P. ventricosus</b> is described on <a href="#Page_69">page 69</a>.</p>
+</div>
+
+<p>gg. Hind legs of the female end in long hairs. <span class="rightalign"><span class="smcap"><b>Tarsoneminæ</b></span></span></p>
+
+<div class="hanging">
+<b>Tarsonemus intectus</b> Karpelles, normally found upon grain,
+is said to attack man in Hungary and Russia. Other
+species of the genus affect various plants (c.f. <a href="#Fig_150">fig.&nbsp;150, g</a>).
+</div></div>
+
+<p>ff. Without tracheæ; no such clavate hair.</p>
+
+<div class="hanging">
+<p>g. Genital suckers usually present; integument usually without
+fine parallel lines.</p>
+
+<div class="hanging">
+<p>h. Legs short, without clavate hair on tarsi&nbsp;I and&nbsp;II. On
+insects. <span class="rightalign"><span class="smcap">Canestrinidæ.</span></span></p>
+
+<p>hh. Legs longer, with a clavate hair on tarsi&nbsp;I and&nbsp;II. Not
+normally parasitic except on bees. <span class="rightalign"><span class="smcap"><b>Tyroglyphidæ</b></span></span></p>
+
+<div class="hanging">
+<p>i. Dorsal integument more or less granulate; claws very weak,
+almost invisible; some hairs of the body plainly feathered;
+ventral apertures large. <span class="rightalign"><b>Glyciphagus</b> Her.</span></p>
+
+<div class="hanging">
+<p>This genus occurs in the United States. In Europe the
+mites have been found feeding on all sorts of substances.
+They are known as sugar mites and cause the disease<span class="pagenum"><a name="Pg_268" id="Pg_268"></a>[Pg 268]</span>
+known as grocer's itch. <b>G. domesticus</b> and <b>G. prunorum</b>
+are old world species (<a href="#Fig_150">fig.&nbsp;150, d</a>).</p>
+</div>
+
+<p>ii. Dorsal integument not granulate; claws distinct; no
+prominent feathered hairs; ventral aperture small.</p>
+
+<div class="hanging">
+<p>j. Mandibles not chelate; elongate, and toothed below;
+body without long hairs; palpi enlarged at tip and
+provided with two divergent bristles. Species feed on
+decaying substances. <span class="rightalign"><i>Histiostoma</i> Kram.</span></p>
+
+<p>jj. Mandibles chelate; palpi not enlarged at the tip, nor
+with two bristles.</p>
+
+<div class="hanging">
+<p>k. No clavate hair on the base of tarsi I and II; no
+suture between cephalothorax and abdomen. Live
+on bees or in their nests. <span class="rightalign"><i>Trichotarsus</i> Can.</span></p>
+
+<p>kk. A clavate or thickened hair at the base of tarsi&nbsp;I and&nbsp;II.</p>
+
+<div class="hanging">
+<p>l. The bristle on the penultimate segment of the legs
+arises from near the middle; no suture between the
+cephalothorax and abdomen. The species, some
+of which occur in the United States, feed on dried
+fruit, etc. <span class="rightalign"><i>Carpoglyphus</i> Robin.</span></p>
+
+<p>ll. The bristle on the penultimate segment of the legs
+arise from near the tip; a suture between cephalothorax
+and abdomen.</p>
+
+<div class="hanging">
+<p>m. Cephalothorax with four distinct and long bristles
+in a transverse row; tarsi&nbsp;I and&nbsp;II about twice
+as long as the preceding segment (<a href="#Fig_150">fig.&nbsp;150&nbsp;f</a>).
+<span class="rightalign"><b>Tyroglyphus</b> Latr.</span></p>
+
+<div class="hanging">
+<p>n. Some bristles on tarsi&nbsp;I and&nbsp;II near middle,
+distinctly spine-like; the sense hair about its
+length from the base of the segment. Several
+species in the United States belong to this
+group.</p>
+
+<p>nn. No spine-like bristles near the middle of the
+tarsi; sense hair not its length from the base
+of the segment.</p>
+
+<div class="hanging">
+<p>o. Of the terminal abdominal bristles, only two
+are about as long as the abdomen; leg I
+of the male greatly thickened and with a
+spine at apex of the femur below. <span class="rightalign"><b>T. farinæ.</b></span></p>
+
+<p>oo. Of the terminal abdominal bristles at least
+six or more are very long, nearly as long
+as the body.</p>
+
+<div class="hanging">
+<p>p. Bristles of the body distinctly plumose or
+pectinate; tarsi very long. <span class="rightalign"><b>T. longior.</b></span></p>
+
+<p>pp. Bristles of the body not pectinate.</p>
+
+<div class="hanging">
+<p>q. In mills, stored foods, grains, etc. Third
+and fourth joints of hind legs scarcely
+twice as long as broad; abdominal
+bristles not unusually long; legs&nbsp;I<span class="pagenum"><a name="Page_269" id="Page_269">[Pg 269]</a></span>
+and&nbsp;II of the male not unusually
+stout. <span class="rightalign"><b>T. americanus.</b></span></p>
+
+<p>qq. With other characters and habits.
+<i>T. lintneri</i> (<a href="#Fig_150">fig.&nbsp;150</a>&nbsp;f) the mushroom
+mite, and several other species.</p>
+</div></div></div></div>
+
+<p>mm. Cephalothorax with but two long distinct
+bristles (besides the frontal pair), but sometimes
+a very minute intermediate pair;
+tarsi&nbsp;I and&nbsp;II unusually short and not twice
+as long as the preceding segment.</p>
+
+<div class="hanging">
+<p>n. Tarsi with some stout spines. <span class="rightalign"><b>Rhizoglyphus</b> Clap.</span></p>
+
+<div class="hanging">
+<p>The species of this genus are vegetable feeders.
+Several occur in the United States.
+<b>R. parasiticus</b> and <b>R. spinitarsus</b> have been
+recorded from the old world, attacking human
+beings who handle affected plants.</p>
+</div>
+
+<p>nn. Tarsi with only fine hairs. <span class="rightalign"><b>Monieziella</b> Berl.</span></p>
+
+<div class="hanging">
+<p>The species of this genus, as far as known,
+are predaceous or feed on recently killed
+animal matter. Several species occur
+in the United States. <b>M.</b> (=&nbsp;<b>Histiogaster</b>)
+<b>entomophaga</b> (<a href="#Fig_152">fig.&nbsp;152</a>) from the old
+world has been recorded as injurious
+to man.</p>
+</div></div></div></div></div></div></div></div>
+
+<p>gg. Genital suckers absent; integument with fine parallel lines.
+Parasitic on birds and mammals.</p>
+
+<div class="hanging">
+<p>h. Possessing a specially developed apparatus for clinging to
+hairs of mammals. <span class="rightalign"><span class="smcap"><b>Listrophoridæ.</b></span></span></p>
+
+<p>hh. Without such apparatus.</p>
+
+<div class="hanging">
+<p>i. Living on the plumage of birds. <span class="rightalign"><span class="smcap">Analgesidæ.</span></span></p>
+
+<p>ii. In the living tissues of birds and mammals.</p>
+
+<div class="hanging">
+<p>j. Vulva longitudinal. In the skin and cellular tissues of
+birds. <span class="rightalign"><span class="smcap">Cytoleichidæ.</span></span></p>
+
+<div class="hanging">
+<p>This family contains two species, both occurring in the
+United States on the common fowl. <i>Laminosioptes
+cysticola</i> occurs on the skin and also bores into the
+subcutaneous tissue where it gives rise to a calcareous
+cyst. <i>Cytoleichus nudus</i> is most commonly
+found in the air passages and air cells.</p>
+</div>
+
+<p>jj. Vulva transverse. In the skin of mammals and birds
+<span class="rightalign"><span class="smcap"><b>Sarcoptidæ</b></span></span></p>
+
+<div class="hanging">
+<p>k. Anal opening on the dorsum.</p>
+
+<div class="hanging">
+<p>l. Third pair of legs in the male without apical suckers.
+On cats and rabbits. <span class="rightalign"><b>Not&oelig;dres</b> Rail.</span></p>
+
+<div class="hanging">
+<p>The itch mite of the cat, <b>N. cati</b> (<a href="#Fig_61">fig.&nbsp;61</a>) has been
+recorded on man.</p>
+</div>
+
+<p>ll. Third leg in the male with suckers. On bats
+<span class="rightalign"><i>Prosopodectes</i> Can.</span><span class="pagenum"><a name="Pg_270" id="Pg_270"></a>[Pg 270]</span></p>
+</div>
+
+<p>kk. Anal opening below.</p>
+
+<div class="hanging">
+<p>l. Pedicel of the suckers jointed; mandibles styliform
+and serrate near the tip. <span class="rightalign"><b>Psoroptes</b> Gerv.</span></p>
+
+<div class="hanging">
+<p><b>P. communis ovis</b> is the cause of sheep scab.</p>
+</div>
+
+<p>ll. Pedicel of the suckers not jointed; mandibles
+chelate.</p>
+
+<div class="hanging">
+<p>m. No suckers on the legs of the females; parasitic
+on birds, including chickens. <i>C. mutans</i> is
+itch mite of chickens. <span class="rightalign"><i>Cnemidocoptes</i> Fürst.</span></p>
+
+<p>mm. Suckers at least on legs&nbsp;I and&nbsp;II; parasitic on
+mammals.</p>
+
+<div class="hanging">
+<p>n. Legs very short; in the male the hind pairs
+equal in size; body usually short.
+<span class="rightalign"><b>Sarcoptes</b> Latr.</span></p>
+
+<div class="hanging">
+<p><b>S. scabiei</b> is the itch mite of man (<a href="#Fig_56a">fig.&nbsp;56</a>).</p>
+</div>
+
+<p>nn. Legs more slender; in the male the third pair
+is much larger than the fourth; body more
+elongate.</p>
+
+<div class="hanging">
+<p>o. Female with suckers on the fourth pair of
+legs. Species do not burrow in the skin,
+but produce a scab similar to sheep scab.
+They occur in the ox, horse, sheep and goat.
+<span class="rightalign"><b>Chorioptes</b> Gerv.</span></p>
+
+<div class="hanging">
+<p><b>C. symbiotes bovis</b> of the ox has been
+recorded a few times on man.</p>
+</div>
+
+<p>oo. Female without suckers to the fourth legs.</p>
+
+<div class="hanging">
+<p>p. Hind part of the male abdomen with two
+lobes. On a few wild animals.
+<span class="rightalign"><i>Caparinia</i> Can.</span><span class="pagenum"><a name="Page_271" id="Page_271">[Pg 271]</a></span></p>
+
+<p>pp. Hind part of the male abdomen without
+lobes. Live in ears of dogs and cats.
+<span class="rightalign"><i>Otodectes</i> Canestr.</span></p>
+
+<div class="hanging">
+<p><i>O. cynotis</i> Hering (<a href="#Fig_150">fig.&nbsp;150&nbsp;e</a>) has been
+taken in the United States.</p>
+</div>
+</div></div></div></div></div></div></div></div></div></div></div>
+
+<p>ee. Palpi usually of four or five segments, free; rarely with ventral
+suckers near genital or anal openings; eyes often present; tarsi
+never end in suckers; body usually divided into cephalothorax
+and abdomen; rod-like epimera rarely visible; adults rarely
+parasitic.</p>
+
+<div class="hanging">
+<p>f. Last segment of the palpi never forms a thumb to the preceding
+segment; palpi simple, or rarely formed to hold prey; body
+with but few hairs. <span class="rightalign"><b>EUPODOIDEA.</b></span></p>
+
+<div class="hanging">
+<p>g. Palpi often geniculate, or else fitted for grasping prey; mandibles
+large and snout like; cephalothorax with four long
+bristles above, two in front, two behind; last segment of leg&nbsp;I
+longer than the preceding segment, often twice as long.
+<span class="rightalign"><span class="smcap">Bdellidæ.</span></span></p>
+
+<p>gg. Palpi never geniculate (<a href="#Fig_158">fig.&nbsp;158a</a>), nor fitted for grasping prey:
+beak small; cephalothorax with bristles in different arrangement;
+last segment of leg I shorter or but little longer than
+the preceding joint; eyes when present near posterior
+border. <span class="rightalign"><span class="smcap"><b>Eupodidæ</b></span></span></p>
+
+<div class="hanging">
+<p>Moniez has described a species from Belgium (<b>Tydeus
+molestus</b>) which attacks man. It is rose colored; eyeless;
+its legs are scarcely as long as its body, the hind
+femur is not thickened; the mandibles are small and the
+anal opening is on the venter. The female attains a
+length of about 0.3 mm.</p>
+</div></div>
+
+<p>ff. Last segment of the palpus forms a thumb to the preceding, which
+ends in a claw (with few exceptions); body often with many
+hairs (<a href="#Fig_158">fig.&nbsp;158&nbsp;k</a>). <span class="rightalign"><b>TROMBIDOIDEA.</b></span></p>
+
+<div class="hanging">
+<p>g. Legs&nbsp;I and&nbsp;II with processes bearing spines; skin with several
+shields; coxæ contiguous. <span class="rightalign"><span class="smcap">Cæculidæ.</span></span></p>
+
+<p>gg. Legs&nbsp;I and&nbsp;II without such processes; few if any shields.</p>
+
+<div class="hanging">
+<p>h. Palpi much thickened on the base, moving laterally, last
+joint often with two pectinate bristles; no eyes; legs&nbsp;I
+ending in several long hairs; adult sometimes parasitic.
+<span class="rightalign"><span class="smcap"><b>Cheyletidæ</b></span></span></p>
+
+<div class="hanging">
+<b>Cheyletus eruditus</b>, which frequents old books, has once
+been found in pus discharged from the ear of man.
+</div>
+
+<p>hh. Palpi less thickened, moving vertically; eyes usually present;
+leg&nbsp;I not ending in long hairs.</p>
+
+<div class="hanging">
+<p>i. Coxæ contiguous, radiate; legs slender, bristly; body with
+few hairs; no dorsal groove; tarsi not swollen.
+<span class="rightalign"><span class="smcap">Erythræidæ.</span></span></p>
+
+<p>ii. Coxæ more or less in two groups; legs less bristly.<span class="pagenum"><a name="Page_273" id="Page_273">[Pg 273]</a></span></p>
+
+<div class="hanging">
+<p>j. Body with fewer, longer hairs; often spinning threads;
+no dorsal groove; tarsi never swollen; mandibles
+styliform (for piercing). <span class="rightalign"><span class="smcap"><b>Tetranychidæ</b></span></span></p>
+
+<div class="hanging">
+<p>The genus <b>Tetranychus</b> may be distinguished from the
+other genera occurring in the United States by the
+following characters: No scale-like projections on
+the front of the cephalothorax; legs I as long or
+longer than the body; palp ends in a distinct thumb;
+the body is about 1.5 times as long as broad. <b>T.&nbsp;molestissimus</b>
+Weyenb. from South America, and
+<b>T.&nbsp;telarius</b> from Europe and America ordinarily
+infesting plants, are said also to molest man.</p>
+</div>
+
+<p>jj. Body with many fine hairs or short spines; not spinning
+threads; often with dorsal groove; tarsi often
+swollen.</p>
+
+<div class="hanging">
+<p>k. Mandibles styliform for piercing. <span class="rightalign"><span class="smcap">Rhycholophidæ.</span></span></p>
+
+<p>kk. Mandibles chelate, for biting. <span class="rightalign"><span class="smcap"><b>Trombididæ</b></span></span></p>
+
+<div class="hanging">
+<p>The genus <b>Trombidium</b> has recently been subdivided
+by Berlese into a number of smaller
+ones, of which some five or six occur in the
+United States. The mature mite is not parasitic
+but the larvæ which are very numerous in
+certain localities will cause intense itching,
+soreness, and even more serious complications.
+They burrow beneath the skin and produce
+inflamed spots. They have received the
+popular name of "<b>red bug</b>." The names <b>Leptus
+americanus</b> and <b>L.&nbsp;irritans</b> have been applied to
+them, although they are now known to be immature
+stages. (<a href="#Fig_44">Fig.&nbsp;44</a>.)</p>
+</div></div></div></div></div></div></div></div></div></div></div></div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_149" id="Fig_149"></a>
+<a href="images/f149-full.png"><img src="images/f149.png" width="500" height="276" alt="149. Hæmaphysalis wellingtoni. Note short palpi. After Nuttall and Warburton." title="149. Hæmaphysalis wellingtoni. Note short palpi. After Nuttall and Warburton." /></a>
+<span class="caption">149. Hæmaphysalis wellingtoni. Note short palpi. After Nuttall and Warburton.</span>
+</div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_150" id="Fig_150"></a>
+<a href="images/f150-full.png"><img src="images/f150.png" width="450" height="653" alt="150. Stigmal plate of Dermacentor andersoni; (a) of
+male, (b) of female. After Stiles. (c) Dermacentor variabilis, male;
+(d) Glyciphagus obesus; (e) Otodectes cynotis; (f) Tyroglyphus
+lintneri; (g) Tarsonemus pallidus; (h) anal plate and mandible of
+Liponyssus; (c) to (h) after Banks." title="150. Stigmal plate of Dermacentor andersoni; (a) of
+male, (b) of female. After Stiles. (c) Dermacentor variabilis, male;
+(d) Glyciphagus obesus; (e) Otodectes cynotis; (f) Tyroglyphus
+lintneri; (g) Tarsonemus pallidus; (h) anal plate and mandible of
+Liponyssus; (c) to (h) after Banks." /></a>
+<span class="caption">150. Stigmal plate of Dermacentor andersoni; (<i>a</i>)&nbsp;of
+male, (<i>b</i>)&nbsp;of female. After Stiles. (<i>c</i>)&nbsp;Dermacentor variabilis, male;
+(<i>d</i>)&nbsp;Glyciphagus obesus; (<i>e</i>)&nbsp;Otodectes cynotis; (<i>f</i>)&nbsp;Tyroglyphus
+lintneri; (<i>g</i>)&nbsp;Tarsonemus pallidus; (<i>h</i>)&nbsp;anal plate and mandible of
+Liponyssus; (<i>c</i>) to (<i>h</i>) after Banks.</span>
+</div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_151" id="Fig_151"></a>
+<a href="images/f151-full.png"><img src="images/f151.png" width="450" height="427" alt="151. Rhipicephalus bursa, male.
+After Nuttall and Warburton." title="151. Rhipicephalus bursa, male.
+After Nuttall and Warburton." /></a>
+<span class="caption">151. Rhipicephalus bursa, male.
+After Nuttall and Warburton.</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_152" id="Fig_152"></a>
+<a href="images/f152-full.png"><img src="images/f152.png" width="500" height="343" alt="152. Monieziella (Histiogaster) emtomophaga-spermatica, ventral aspect,
+male and female. After Trouessart." title="152. Monieziella (Histiogaster) emtomophaga-spermatica, ventral aspect,
+male and female. After Trouessart." /></a>
+<span class="caption">152. Monieziella (Histiogaster) emtomophaga-spermatica, ventral aspect,
+male and female. After Trouessart.</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_153" id="Fig_153"></a>
+<a href="images/f153-full.png"><img src="images/f153.png" width="500" height="329" alt="153. Rhipicentor bicornis, ventral aspect, male. After Nuttall and
+Warburton." title="153. Rhipicentor bicornis, ventral aspect, male. After Nuttall and
+Warburton." /></a>
+<span class="caption">153. Rhipicentor bicornis, ventral aspect, male. After Nuttall and
+Warburton.</span>
+</div>
+
+<div class="figcenter" style="width: 425px;"><a name="Fig_154" id="Fig_154"></a>
+<a href="images/f154-full.png"><img src="images/f154.png" width="425" height="407" alt="154. Rhicephalus sanguineus, male.
+After Nuttall and Warburton." title="154. Rhicephalus sanguineus, male.
+After Nuttall and Warburton." /></a>
+<span class="caption">154. Rhicephalus sanguineus, male.
+After Nuttall and Warburton.</span>
+</div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_155" id="Fig_155"></a>
+<a href="images/f155-full.png"><img src="images/f155.png" width="450" height="396" alt="155. Margaropus winthemi, male. After
+Nuttall and Warburton." title="155. Margaropus winthemi, male. After
+Nuttall and Warburton." /></a>
+<span class="caption">155. Margaropus winthemi, male. After
+Nuttall and Warburton.</span>
+</div>
+
+<div class="figcenter" style="width: 200px;"><a name="Fig_156" id="Fig_156"></a>
+<a href="images/f156-full.png"><img src="images/f156.png" width="200" height="294" alt="156. Margaropus winthemi,
+capitulum and scutum.
+After Nuttall and Warburton." title="156. Margaropus winthemi,
+capitulum and scutum.
+After Nuttall and Warburton." /></a>
+<span class="caption">156. Margaropus winthemi,
+capitulum and scutum.
+After Nuttall and Warburton.</span>
+</div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_157" id="Fig_157"></a>
+<a href="images/f157-full.png"><img src="images/f157.png" width="350" height="400" alt="157. Amblyomma, female. After Nuttall
+and Warburton." title="157. Amblyomma, female. After Nuttall
+and Warburton." /></a>
+<span class="caption">157. Amblyomma, female. After Nuttall
+and Warburton.</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_158" id="Fig_158"></a>
+<a href="images/f158-full.png"><img src="images/f158.png" width="500" height="706" alt="158. (a) Tydeus, beak and leg from below; (b) Cheyletus pyriformis, beak and palpus;
+(c) beak and claw of Pediculoides; (d) leg of Sarcoptes; (e) scutum of
+female of Amblyomma americana; (f) leg I and tip of mandible of Histiostoma
+americana; (g) Histiogaster malus, mandible and venter; (h) Aleurobius
+farinæ, and leg I of male; (i) Otodectes cynotis, tip of abdomen of male,
+(j) beak and anal plate of Dermanyssus gallinæ; (k) palpus of Allothrombium.
+(a) to (j) after Banks." title="158. (a) Tydeus, beak and leg from below; (b) Cheyletus pyriformis, beak and palpus;
+(c) beak and claw of Pediculoides; (d) leg of Sarcoptes; (e) scutum of
+female of Amblyomma americana; (f) leg I and tip of mandible of Histiostoma
+americana; (g) Histiogaster malus, mandible and venter; (h) Aleurobius
+farinæ, and leg I of male; (i) Otodectes cynotis, tip of abdomen of male,
+(j) beak and anal plate of Dermanyssus gallinæ; (k) palpus of Allothrombium.
+(a) to (j) after Banks." /></a>
+<span class="caption">158. (<i>a</i>)&nbsp;Tydeus, beak and leg from below; (<i>b</i>)&nbsp;Cheyletus pyriformis, beak and palpus;
+(<i>c</i>)&nbsp;beak and claw of Pediculoides; (<i>d</i>)&nbsp;leg of Sarcoptes; (<i>e</i>)&nbsp;scutum of
+female of Amblyomma americana; (<i>f</i>)&nbsp;leg&nbsp;I and tip of mandible of Histiostoma
+americana; (<i>g</i>)&nbsp;Histiogaster malus, mandible and venter; (<i>h</i>)&nbsp;Aleurobius
+farinæ, <span title="insert &quot;palpus&quot; before &quot;and leg&quot;"><a name="AC_14" id="AC_14"></a>and leg&nbsp;I</span> of male; (<i>i</i>)&nbsp;Otodectes cynotis, tip of abdomen of male,
+(<i>j</i>)&nbsp;beak and anal plate of Dermanyssus gallinæ; (<i>k</i>)&nbsp;palpus of Allothrombium.
+(<i>a</i>)&nbsp;to&nbsp;(<i>j</i>) after Banks.</span>
+</div>
+
+
+<h3><a name="HEXAPODA_Insecta" id="HEXAPODA_Insecta"></a>HEXAPODA (Insecta)</h3>
+
+<p>The Thysanura (springtails and bristletails), the Neuropteroids
+(may-flies, stone-flies, dragon-flies, caddis-flies, etc.), Mallophaga
+(bird lice), Physopoda (thrips), Orthoptera (grasshoppers, crickets,
+roaches), are of no special interest from our viewpoint. The remaining
+orders are briefly characterized below.</p>
+
+
+<h3>SIPHUNCULATA (<a href="#Page_275">page 275</a>)</h3>
+
+<p>Mouth parts suctorial; beak fleshy, not jointed; insect wingless;
+parasitic upon mammals. Metamorphosis incomplete. Lice.</p>
+
+
+<h3>HEMIPTERA (<a href="#Page_275">page 275</a>)</h3>
+
+<p>Mouth parts suctorial; beak or the sheath of the beak jointed;
+in the mature state usually with four wings. In external appearance<span class="pagenum"><a name="Page_274" id="Page_274">[Pg 274]</a></span>
+the immature insect resembles the adult except that the immature
+form (i.e. nymph) never has wings, the successive instars during
+the process of growth, therefore, are quite similar; and the metamorphosis
+is thus incomplete. To this order belong the true bugs,
+the plant lice, leaf hoppers, frog hoppers, cicadas, etc.</p>
+
+
+<h3>LEPIDOPTERA</h3>
+
+<p>The adult insect has the body covered with scales and (with the
+rare exception of the females of a few species) with four wings also
+covered with scales. Proboscis, when present, coiled, not segmented,
+adapted for sucking. Metamorphosis complete, i.e. the
+young which hatches from the egg is quite unlike the adult, and after
+undergoing several molts transforms into a quiescent pupa which is
+frequently enclosed in a cocoon from which the adult later emerges.
+The larvæ are known as caterpillars. Butterflies and moths.</p>
+
+
+<h3>DIPTERA (<a href="#Page_285">page 285</a>)</h3>
+
+<p>The adult insect is provided with two, usually transparent,
+wings, the second pair of wings of other insects being replaced by a
+pair of halteres or balancers. In a few rare species the wings, or
+halteres, or both, are wanting. The mouth parts, which are not
+segmented, are adapted for sucking. The tarsi are five-segmented.
+Metamorphosis complete. The larvæ, which are never provided
+with jointed legs, are variously known as maggots, or grubs, or
+wrigglers. Flies, midges, mosquitoes.</p>
+
+
+<h3>SIPHONAPTERA (<a href="#Page_316">page 316</a>)</h3>
+
+<p>Mouth parts adapted for sucking; body naked or with bristles
+and spines; prothorax well developed; body compressed; tarsi
+with five segments; wings absent. Metamorphosis complete.
+The larva is a wormlike creature. Fleas.</p>
+
+
+<h3>COLEOPTERA</h3>
+
+<p>Adult with four wings (rarely wanting), the first pair horny or
+leathery, veinless, forming wing covers which meet in a line along
+the middle of the back. Mouth parts of both immature stages and
+adults adapted for biting and chewing. Metamorphosis complete.
+The larvæ of many species are known as grubs. Beetles.<span class="pagenum"><a name="Page_275" id="Page_275">[Pg 275]</a></span></p>
+
+
+<h3>HYMENOPTERA</h3>
+
+<p>Adult insect with four, usually transparent, wings, wanting in
+some species. Mouth parts adapted for biting and sucking; palpi
+small; tarsi four or five-segmented. Metamorphosis complete.
+Parasitic four-winged flies, ants, bees, and wasps.</p>
+
+
+<h3><a name="SIPHUNCULATA_AND_HEMIPTERA" id="SIPHUNCULATA_AND_HEMIPTERA"></a>SIPHUNCULATA AND HEMIPTERA</h3>
+
+<div class="hanging">
+<p>a. Legs with claws fitted for clinging to hairs; wings wanting; spiracles of the
+abdomen on the dorsal surface. (=&nbsp;<b>ANOPLURA</b> =&nbsp;<b>PARASITICA</b>)
+<span class="rightalign"><b>SIPHUNCULATA.</b></span></p>
+
+<div class="hanging">
+<p>b. Legs not modified into clinging hooks; tibia and tarsus very long and
+slender; tibia without thumb-like process; antennæ five-segmented.
+<span class="rightalign"><span class="smcap">Hæmatomyzidæ</span> Endr.</span></p>
+
+<div class="hanging">
+<p><i>Hæmatomyzus elephantis</i> on the elephant.</p>
+</div>
+
+<p>bb. Legs modified into clinging hooks; tibia and tarsus usually short and
+stout; tibia with a thumb-like process; head not anteriorly prolonged,
+tube-like.</p>
+
+<div class="hanging">
+<p>c. Body depressed; a pair of stigmata on the mesothorax, and abdominal
+segments three to eight; antennæ three to five-segmented.</p>
+
+<div class="hanging">
+<p>d. Eyes large, projecting, distinctly pigmented; pharynx short and
+broad; fulturæ (inner skeleton of head) very strong and broad,
+with broad arms; proboscis short, scarcely attaining the thorax.
+<span class="rightalign"><span class="smcap"><b>Pediculidæ</b></span></span></p>
+
+<div class="hanging">
+<p>e. Antennæ three-segmented. A few species occurring upon old
+world monkeys. <span class="rightalign"><i>Pedicinis</i> Gerv.</span></p>
+
+<p>ee. Antennæ five-segmented.</p>
+
+<div class="hanging">
+<p>f. All legs stout; thumb-like process of the tibia very long and
+slender, beset with strong spines, fore legs stouter than the
+others; abdomen elongate, segments without lateral processes;
+the divided telson with a conical process posteriorly
+upon the ventral side. <span class="rightalign"><b>Pediculus</b> L.</span></p>
+
+<div class="hanging">
+<p>g. Upon man.</p>
+
+<div class="hanging">
+<p>h. Each abdominal segment dorsally with from one to three
+more or less regular transverse rows of small setæ;
+antenna about as long as the width of the head. Head
+louse (<a href="#Fig_65">fig.&nbsp;65</a>). <span class="rightalign"><b>P. humanus.</b></span></p>
+
+<p>hh. "No transverse rows of abdominal setæ; antenna longer
+than the width of the head; species larger." Piaget.
+Body louse of man. <span class="rightalign"><b>P. corporis.</b></span></p>
+</div>
+
+<p>gg. Upon apes and other mammals. <span class="rightalign"><i>P. pusitatus</i>&nbsp;(?).</span></p>
+</div>
+
+<p>ff. Fore legs delicate, with very long and slender claws; other legs
+very stout with short and stout claws; thumb-like process of
+the tibia short and stout; abdomen very short and broad;
+segment one to five closely crowded, thus the stigmata of segments
+three to five apparently lying in one segment; segments
+five to eight with lateral processes; telson without lateral
+conical appendages (<a href="#Fig_69">fig.&nbsp;69</a>). Crab louse of man.
+<span class="rightalign"><b>Phthirus pubis.</b></span><span class="pagenum"><a name="Page_276" id="Page_276">[Pg 276]</a></span></p>
+</div></div>
+
+<p>dd. Eyes indistinct or wanting; pharynx long and slender, fulturæ very
+slender and closely applied to the pharynx; proboscis very long.
+Several genera found upon various mammals. <span class="rightalign"><span class="smcap">Hæmatopinidæ.</span></span></p>
+</div>
+
+<p>cc. Body swollen; meso- and metathorax, and abdominal segments two to
+eight each with a pair of stigmata; eyes wanting; antennæ four or
+five-segmented; body covered with stout spines. Three genera found
+upon marine mammals. <span class="rightalign"><span class="smcap">Echinophthiriidæ</span></span></p>
+</div></div>
+
+<p>aa. Legs fitted for walking or jumping; spiracles of abdomen usually ventral;
+beak segmented.</p>
+
+<div class="hanging">
+<p>b. Apex of head usually directed anteriorly; beak arising from its apex; sides
+of the face remote from the front coxæ; first pair of wings when present
+thickened at base, with thinner margins. <span class="rightalign"><b>HETEROPTERA</b></span></p>
+
+<div class="hanging">
+<p>c. Front tarsi of one segment, spade-form (palæformes); beak short, at
+most two-segmented; intermediate legs long, slender; posterior pair
+adapted for swimming. <span class="rightalign"><span class="smcap">Corixidæ</span></span></p>
+
+<p>cc. Front tarsi rarely one-segmented, never spade-form; beak free, at least
+three-segmented.</p>
+
+<div class="hanging">
+<p>d. Pulvilli wanting.</p>
+
+<div class="hanging">
+<p>e. Hemelytra usually with a distinct clavus (<a href="#Fig_159">fig.&nbsp;159</a>), clavus always
+ends behind the apex of the scutellum, forming the commissure.
+(Species having the wings much reduced or wanting should be
+sought for in both sections.)</p>
+
+<div class="hanging">
+<p>f. Antennæ very short; meso- and metasternum composite; eyes
+always present.<span class="pagenum"><a name="Page_277" id="Page_277">[Pg 277]</a></span></p>
+
+<div class="hanging">
+<p>g. Ocelli present; beak four-segmented. <span class="smcap">Ochteridæ</span> and
+<span class="smcap">Nerthridæ</span>.</p>
+
+<p>gg. Ocelli wanting; antennæ more or less hidden in a groove.</p>
+
+<div class="hanging">
+<p>h. Anterior coxæ inserted at or near anterior margin of the
+prosternum; front legs raptorial; beak three-segmented.
+<span class="smcap"><b>Belostomidæ</b></span> (with swimming legs), <span class="smcap">Nepidæ</span>, <span class="smcap">Naucoridæ</span>.</p>
+
+<div class="hanging">
+<p>i. Metasternum without a median longitudinal keel; antennæ
+always four-segmented.</p>
+
+<div class="hanging">
+<p>j. Beak short, robust, conical; the hairy fleck on the corium
+elongate, large, lying in the middle between the inner
+angle of the membrane and the outer vein parallel to
+the membrane margin; membrane margin S-shaped.</p>
+
+<div class="hanging">
+<p>k. The thick fore femur with a relatively deep longitudinal
+furrow to receive the tibia. Several American
+species (<a href="#Fig_19">fig.&nbsp;19f.</a>). <span class="rightalign"><b>Belostoma</b> (=&nbsp;Lethocerus Mayer)</span></p>
+
+<p>kk. The less thickened fore femur without such a furrow.
+<span class="rightalign"><b>B. griseus.</b> <b>Benacus</b> Stäl.</span></p>
+</div>
+
+<p>jj. Beak slender, cylindrical; the hairy spot on the corium
+rounded lying next to the inner angle of the membrane.</p>
+
+<div class="hanging">
+<p>k. Membrane large, furrow of the embolium broadened.
+<i>Z. aurantiacum</i>, <i>fluminea</i>, etc. <span class="rightalign"><i>Zaitha</i></span></p>
+
+<p>kk. Membrane very short; furrow of embolium not
+broadened. Western genus. <span class="rightalign"><i>Pedinocoris</i></span></p>
+</div></div>
+
+<p>ii. Metasternum with a long median longitudinal keel. Southwestern
+forms. <span class="rightalign"><i>Abedus ovatus</i> and <i>Deniostoma dilatato</i></span></p>
+</div>
+
+<p>hh. Anterior coxæ inserted at the posterior margin of the
+prosternum; legs natatorial. Back swimmers (<a href="#Fig_19">fig.&nbsp;19&nbsp;b.</a>).
+<span class="rightalign"><span class="smcap"><b>Notonectidæ</b></span></span></p>
+
+<div class="hanging">
+<p>i. Apices of the hemelytra entire; the three pairs of legs
+similar in shape; beak three-segmented; abdomen not
+keeled or hairy. <span class="rightalign"><i>Plea</i> Leach</span></p>
+
+<p>ii. Apices of hemelytra notched; legs dissimilar; beak four-segmented;
+abdomen keeled and hairy.</p>
+
+<div class="hanging">
+<p>j. Hemelytra usually much longer than the abdomen;
+fourth segment of the antenna longer than the third
+segment; hind tarsi with claws. <span class="rightalign"><i>Bueno</i> Kirk.</span></p>
+
+<p>jj. Hemelytra but little longer than the abdomen; fourth
+segment of the antenna shorter than the third segment;
+hind tarsi without claws (<a href="#Fig_19">fig.&nbsp;19b</a>). <span class="rightalign"><b>Notonecta L.</b></span></p>
+</div></div></div></div>
+
+<p>ff. Antennæ longer than the head; or if shorter, then the eyes and
+ocelli absent.</p>
+
+<div class="hanging">
+<p>g. Eyes, ocelli, and scutellum wanting; beak three-segmented;
+head short; hemelytra always short; membrane wanting.
+Insects parasitic on bats. <span class="rightalign"><span class="smcap">Polyctenidæ</span></span></p>
+
+<p>gg. Eyes present.</p>
+
+<div class="hanging">
+<p>h. First two antennal segments very short, last two long, pilose,
+third thickened at the base; ocelli present, veins of the
+hemelytra forming cells. <span class="smcap">Dipsocoridæ</span> (=&nbsp;<span class="smcap">Ceratocombidæ</span>)
+including <span class="smcap">Schizopteridæ</span>.<span class="pagenum"><a name="Page_278" id="Page_278">[Pg 278]</a></span></p>
+
+<p>hh. Third segment of the antenna not thickened at the base,
+second as long or longer than the third, rarely shorter.</p>
+
+<div class="hanging">
+<p>i. Posterior coxæ hinged (cardinate), if rarely rotating, the
+cuneus is severed, the membrane is one or two-celled,
+and the meso- and metasternum are composite.</p>
+
+<div class="hanging">
+<p>j. Ocelli absent, clypeus dilated toward the apex; hemelytra
+always short, membrane wanting. Species parasitic.
+Bed bugs, etc. <span class="rightalign"><span class="smcap"><b>Cimicidæ</b></span></span></p>
+
+<div class="hanging">
+<p>k. Beak short, reaching to about the anterior coxæ;
+scutellum acuminate at the apex; lateral margin of
+the elytra but little reflexed, apical margin more or
+less rounded; intermediate and posterior coxæ
+very remote.</p>
+
+<div class="hanging">
+<p>l. Body covered with short hairs, only the sides of the
+pronotum and the hemelytra fringed with longer
+hairs; antennæ with the third and fourth segments
+very much more slender than the first and
+second; pronotum with the anterior margin very
+<i>deeply sinuate</i>. <span class="rightalign"><b>Cimex</b> L.</span></p>
+
+<div class="hanging">
+<p>m. Sides of the pronotum widely dilated, broader
+than the breadth of one eye, and densely
+fringed with backward curved hairs; apical
+margin of the hemelytra nearly straight, rounded
+toward the interior or exterior angles.</p>
+
+<div class="hanging">
+<p>n. Body covered with very short hairs; second
+segment of the antenna shorter than the third;
+sides of the pronotum feebly reflexed, fringed
+with shorter hairs than the breadth of one
+eye; hemelytra with the commissural (inner)
+margin rounded and shorter than the scutellum,
+apical margin rounded towards the
+interior angle. The common bed bug (<a href="#Fig_19">fig.&nbsp;19h</a>).
+<span class="rightalign"><b>C. lectularius</b> Linn</span></p>
+
+<p>nn. Body covered with longer hairs; second and
+third segments of the antenna of equal
+length; side of the pronotum narrowly, but
+distinctly, reflexed, fringed with longer
+hairs than the breadth of one eye; hemelytra
+with the commissural margin straight and
+longer than the scutellum, apical margin
+rounded towards the exterior angle. Species
+found on bats in various parts of the United
+States. <span class="rightalign"><i>C. pillosellus</i> Hov.</span></p>
+</div>
+
+<p>mm. Sides of the pronotum neither dilated, nor
+reflexed, fringed with less dense and nearly
+straight hairs; hemelytra with the apical
+margin distinctly rounded. Parasitic on
+man, birds and bats. Occurs in the old
+world, Brazil and the West Indies.
+<span class="rightalign"><b>C. hemipterus</b> Fabr. (=&nbsp;rotundatus)</span><span class="pagenum"><a name="Page_279" id="Page_279">[Pg 279]</a></span></p>
+</div>
+
+<p>ll. Body clothed with rather longer silky hairs; third
+and fourth segments of the antenna somewhat
+more slender than the first and second; anterior
+margin of the pronotum <i>very slightly sinuate</i> or
+nearly straight in the middle, produced at the
+lateral angles. This is the species which in American
+collections is known as <i>C. hirundinis</i>, the
+latter being an old world form. It is found in
+swallows nests. <b>O. vicarius</b>. <span class="rightalign"><b>Oeciacus</b> Stäl</span></p>
+</div>
+
+<p>kk. Beak long, reaching to the posterior coxæ; scutellum
+rounded at the apex; lateral margins of the elytra
+strongly reflexed, apical margin slightly sinuate
+toward the middle; intermediate and posterior
+coxæ sub-contiguous. This species infests poultry
+in southwest United States and in Mexico. <b>H.
+inodorus.</b> <span class="rightalign"><b>Hæmatosiphon</b> Champ.</span></p>
+</div>
+
+<p>jj. Ocelli present, if rarely absent in the female, then the
+tarsus has two segments; or if with three tarsal segments,
+the wing membrane with one or two cells.</p>
+
+<div class="hanging">
+<p>k. Beak four-segmented, or with two-segmented tarsi.
+<span class="smcap">Isometopidæ</span>, <span class="smcap">Microphysidæ</span>, and some <span class="smcap">Capsidæ</span>.</p>
+
+<p>kk. Beak three-segmented.</p>
+
+<div class="hanging">
+<p>l. Hemelytra with embolium; head horizontal, more
+or less conical; membrane with one to four veins,
+rarely wanting. <span class="rightalign"><span class="smcap"><b>Anthocoridæ</b></span></span></p>
+
+<div class="hanging">
+<p>Several species of this family affecting man have
+been noted, <b>Anthocoris kingi</b> and <b>congolense</b>,
+from Africa and <b>Lyctocoris campestris</b> from
+various parts of the world. <b>Lyctocoris fitchii</b>
+Reuter (<a href="#Fig_19">fig.&nbsp;19&nbsp;j</a>), later considered by Reuter as
+a variety of <b>L.&nbsp;campestris</b>, occurs in the United
+States.</p>
+</div>
+
+<p>ll. Hemelytra without embolium. Superfamily <span class="smcap">Acanthioidea</span>
+(=&nbsp;<span class="smcap">Saldæ</span> Fieber and <span class="smcap">Leptopodæ</span>
+Fieber)<span class="pagenum"><a name="Page_280" id="Page_280">[Pg 280]</a></span></p>
+</div></div></div>
+
+<p>ii. Posterior coxæ rotating.</p>
+
+<div class="hanging">
+<p>j. Claws preapical; aquatic forms. <span class="rightalign"><span class="smcap">Gerridæ</span> and <span class="smcap">Veliadæ</span></span></p>
+
+<p>jj. Claws apical.</p>
+
+<div class="hanging">
+<p>k. Prosternum without stridulatory sulcus (notch for
+beak).</p>
+
+<div class="hanging">
+<p>l. Tarsus with three segments; membrane with two or
+three longitudinal cells from which veins radiate;
+rarely with free longitudinal veins (Arachnocoris)
+or veins nearly obsolete (Arbela); clavus and
+corium coriaceous; ocelli rarely absent. <span class="rightalign"><span class="smcap"><b>Nabidæ</b></span></span></p>
+
+<div class="hanging">
+<p><b>Reduviolus</b> (=&nbsp;<b>Coriscus</b>) <b>subcoleoptratus</b> (<a href="#Fig_19">fig.&nbsp;19&nbsp;g</a>),
+a species belonging to this family, occurring in
+the United States, has been accused of biting
+man. This insect is flat, of a jet black color,
+bordered with yellow on the sides of the abdomen,
+and with yellowish legs. It is predaceous,
+feeding on other insects.</p>
+</div>
+
+<p>ll. With other combinations of characters. <span class="smcap">Hydrometridæ</span>,
+<span class="smcap">Henicocephalidæ</span>, <span class="smcap">Næogeidæ</span>, <span class="smcap">Mesoveliadæ</span>,
+<span class="smcap">Joppeicidæ</span></p>
+</div>
+
+<p>kk. Prosternum with stridulatory sulcus (notch for beak);
+with three segments, short, strong.</p>
+
+<p>l. Antennæ filiform or sometimes more slender apically,
+geniculate; wing membrane with two or three
+large basal cells; scutellum small or moderate
+<span class="rightalign"><span class="smcap"><b>Reduviidæ</b></span></span></p>
+
+<div class="hanging">
+<p>For a key to the genera and species see <a href="#Reduviidae_of_the_United_States">next page</a>.</p>
+</div>
+
+<p>ll. Last antennal segment clavate or fusiform; win
+membrane with the veins often forked and anastomosing;
+scutellum large; tarsi each with two
+segments; fore legs strong. (=&nbsp;<span class="smcap">Phymatidæ</span>)
+<span class="rightalign"><span class="smcap">Macrocephalidæ</span></span></p>
+</div></div></div></div></div></div>
+
+<p>ee. Clavus noticeably narrowed towards the apex, never extending
+beyond the scutellum, the two not meeting to form a commissure;
+head horizontal, much prolonged between the antennæ, on each
+side with an antennal tubercle, sometimes acute; ocelli absent;
+meso- and metasternum simple; tarsi each with two segments;
+body flattened (<a href="#Fig_19">fig.&nbsp;19c</a>). <span class="smcap">Aradidæ</span>, including <span class="smcap">Dysodiidæ</span>.</p>
+</div>
+
+<p>dd. Pulvilli present (absent in one Australian family <span class="smcap">Thaumatocoridæ</span>
+in which case there is a membranous appendage at the tip of the
+tibia). <span class="smcap"><b>Capsidæ</b></span> (=&nbsp;<span class="smcap"><b>Miridæ</b></span>),<a name="FNanchor_G_7" id="FNanchor_G_7"></a><a href="#Footnote_G_7" class="fnanchor">[G]</a> <i>Eotrechus</i> (in family <span class="smcap">Gerridæ</span>),
+<span class="smcap">Næogaidæ</span>, <span class="smcap">Tingitidæ</span>, <span class="smcap">Piesmidæ</span>, <span class="smcap">Myodochidæ</span>, <span class="smcap">Corizidæ</span>,
+<span class="smcap">Coreidæ</span>, <span class="smcap">Alydidæ</span>, <span class="smcap">Pentatomidæ</span>, <span class="smcap">Scutelleridæ</span>, etc.</p>
+</div></div>
+
+<p>bb. Apex of head directed ventrally, beak arising from the hinder part of the
+lower side of the head; sides of face contiguous to the front coxæ; first<span class="pagenum"><a name="Page_281" id="Page_281">[Pg 281]</a></span>
+pair of wings, when present, of uniform thickness. Cicadas, scale
+insects, plant lice (Aphids), spittle-insects, leaf hoppers, etc.
+<span class="rightalign">HOMOPTERA</span></p>
+</div></div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_159" id="Fig_159"></a>
+<a href="images/f159-full.png"><img src="images/f159.png" width="500" height="358" alt="159. Taxonomic details of Hemiptera-Heteroptera. (a) Dorsal aspect; (b) seta from
+bedbug; (c) wing of Heteropteron; (d) leg; (e) wing of Sinea." title="159. Taxonomic details of Hemiptera-Heteroptera. (a) Dorsal aspect; (b) seta from
+bedbug; (c) wing of Heteropteron; (d) leg; (e) wing of Sinea." /></a>
+<span class="caption">159. Taxonomic details of Hemiptera-Heteroptera. (<i>a</i>)&nbsp;Dorsal aspect; (<i>b</i>)&nbsp;seta from
+bedbug; (<i>c</i>)&nbsp;wing of Heteropteron; (<i>d</i>)&nbsp;leg; (<i>e</i>)&nbsp;wing of Sinea.</span>
+</div>
+
+<div class="figcenter" style="width: 250px;"><a name="Fig_160" id="Fig_160"></a>
+<a href="images/f160-full.png"><img src="images/f160.png" width="250" height="285" alt="160. Pselliopsis (Milyas)
+cinctus (×2). After
+C. V. Riley." title="160. Pselliopsis (Milyas)
+cinctus (×2). After
+C. V. Riley." /></a>
+<span class="caption">160. Pselliopsis (Milyas)
+cinctus (×2). After
+C.&nbsp;V. Riley.</span>
+</div>
+
+
+<h3><a name="Reduviidae_of_the_United_States" id="Reduviidae_of_the_United_States"></a><span class="smcap">Reduviidæ of the United States</span></h3>
+
+<p class="center">(Adapted from a key given by Fracker).</p>
+
+<div class="hanging">
+<p>a. Ocelli none; wings and hemelytra always present in the adults; no <span title="for discodial read discoidal"><a name="AC_15" id="AC_15"></a>discodial</span>
+areole in the corium near the apex of the clavus. <i>Orthometrops decorata</i>,
+<i>Oncerotrachelus acuminatus</i>, etc., Pennsylvania and south. <span class="rightalign"><i>Sarcinæ</i></span></p>
+
+<p>aa. Ocelli present in the winged individuals; anterior coxæ not as long as the
+femora.</p>
+
+<div class="hanging">
+<p>b. Hemelytra without a quadrangular or discoidal areole in the corium near
+the apex of the clavus.</p>
+
+<div class="hanging">
+<p>c. Ocelli not farther cephalad than the caudal margins of the eyes; segment
+two of the antenna single.</p>
+
+<div class="hanging">
+<p>d. Thorax usually constricted caudad of the middle; anterior coxæ externally
+flat or concave. <span class="rightalign"><span class="smcap"><b>Piratinæ</b></span></span></p>
+
+<div class="hanging">
+<p>e. Middle tibiæ without spongy fossa, head long, no lateral tubercle
+on neck. <i>S. stria</i>, Carolina, Ill., Cal. <span class="rightalign"><i>Sirthenia</i> Spinola</span></p>
+
+<p>ee. Middle tibiæ with spongy fossa; fore tibiæ convex above; neck
+with a small tubercle on each side.</p>
+
+<div class="hanging">
+<p>f. Apical portion of anterior tibiæ angularly dilated beneath, the
+spongy fossa being preceded by a small prominence.
+<span class="rightalign"><b>Melanolestes</b> Stäl</span></p>
+
+<div class="hanging">
+<p>g. Black, with piceous legs and antennæ. N.&nbsp;E. States (<a href="#Fig_19">fig.&nbsp;19a</a>)
+<span class="rightalign"><b>M. picipes</b></span></p>
+
+<p>gg. Sides, and sometimes the whole dorsal surface of the abdomen
+red. Ill., and southward. <span class="rightalign"><b>M. abdominalis</b></span></p>
+</div>
+
+<p>ff. Tibiæ not dilated as in "f"; spongy fossa elongate; metapleural
+sulci close to the margin. <b>R. biguttatus</b> (<a href="#Fig_22">fig.&nbsp;22</a>). South.
+<span class="rightalign"><b>Rasahus</b> A.&nbsp;and&nbsp;S.</span></p>
+</div></div>
+
+<p>dd. Thorax constricted in the middle or cephalad of the middle; anterior
+tarsi each three-segmented.</p>
+
+<div class="hanging">
+<p>e. Apex of the scutellum narrow, without spines or with a single spine
+<span class="rightalign"><span class="smcap"><b>Reduviinæ</b></span></span></p>
+
+<div class="hanging">
+<p>f. Antennæ inserted in the lateral or dorso-lateral margins of the head;
+antenniferous tubercles slightly projecting from the sides of the
+head; head produced strongly cephalad; ocelli at least as far
+apart as the eyes.</p>
+
+<div class="hanging">
+<p>g. Antennæ inserted very near the apex of the head; segments
+one and three of the beak short, segment two nearly four
+times as long as segment one. <b>R. prolixus.</b> W.&nbsp;I.
+<span class="rightalign"><b>Rhodnius</b> Stäl</span></p>
+
+<p>gg. Antennæ inserted remote from the vertex of the head.</p>
+
+<div class="hanging">
+<p>h. Body slightly hairy; pronotum distinctly constricted; angles
+distinct; anterior lobe four-tuberculate, with the middle
+tubercles large and conical. <i>M. phyllosoma</i>, large species
+<span title="insert &quot;from&quot; before &quot;the&quot;"><a name="AC_16" id="AC_16"></a>the</span> southwest. <span class="rightalign"><i>Meccus</i> Stäl</span><span class="pagenum"><a name="Page_282" id="Page_282">[Pg 282]</a></span></p>
+
+<p>hh. Body smooth, margin of the pronotum sinuous, scarcely
+constricted; anterior lobe lined with little tubercles.
+<span class="rightalign"><b>Conorhinus</b> Lap.</span></p>
+
+<div class="hanging">
+<p>i. Surface of the pronotum and prosternum more or less
+granular.</p>
+
+<div class="hanging">
+<p>j. Eyes small, head black; body very narrow, a fifth as
+wide as long; beak reaches the middle of the prosternum.
+California. <span class="rightalign"><b>C. protractus</b></span></p>
+
+<p>jj. Eyes large, head fuscous; body at least a fourth as wide
+as long. Southern species. <span class="rightalign"><i>C. rubrofasciatus</i></span></p>
+</div>
+
+<p>ii. Pronotum and prosternum destitute of granules.</p>
+
+<div class="hanging">
+<p>j. Border of abdomen entirely black except for a narrow
+yellowish spot at the apex of one segment. Texas
+<span class="rightalign"><i>C. gerstaeckeri</i></span></p>
+
+<p>jj. Border of abdomen otherwise marked.</p>
+
+<div class="hanging">
+<p>k. Beak slender, joints one and two slightly pilose, two
+more than twice as long as one; tubercles at the
+apical angles of the pronotum slightly acute, conical.
+Md. to Ill. and south. The masked bed bug hunter
+(<a href="#Fig_71">fig.&nbsp;71</a>). <span class="rightalign"><b>C. sanguisugus</b></span></p>
+
+<p>kk. Beak entirely pilose, joint two a third longer than
+joint one; joint one much longer than three;
+tubercles at the apical angles of pronotum slightly
+elevated, obtuse. Ga., Ill., Tex., Cal. <span class="rightalign"><i>C. variegatus</i></span></p>
+</div></div></div></div></div>
+
+<p>ff. Antenna inserted on top of the head between margins, close to the
+eyes; antenniferous tubercles not projecting from the side of the
+head.</p>
+
+<div class="hanging">
+<p>g. Anterior lobe of the pronotum with a bispinous or bituberculate
+disc; femora unarmed. <i>S.&nbsp;arizonica</i>, <i>S.&nbsp;bicolor</i>. Southwestern
+species. <span class="rightalign"><i>Spiniger</i> Burm.</span></p>
+
+<p>gg. Disc of pronotum unarmed; apex of scutellum produced into
+a spine; ocelli close to the eyes; eyes large and close together.
+<span class="rightalign"><b>Reduvius</b> Lamarck</span></p>
+
+<div class="hanging">
+<p>h. Color piceous. Widely distributed in the United States.
+(<a href="#Fig_20">Fig.&nbsp;20</a>). <span class="rightalign"><b>R. personatus</b></span></p>
+
+<p>hh. More or less testaceous in color. Southwestern states
+<span class="rightalign"><b>R. senilis</b></span></p>
+</div></div></div>
+
+<p>ee. Apex of scutellum broad, with two or three spines. <span class="rightalign"><span class="smcap">Ectrichodiinæ</span></span></p>
+
+<div class="hanging">
+<p>f. First segment of the antenna about as long as the head. <span class="rightalign"><i>E. cruciata</i></span></p>
+
+<div class="hanging">
+<p>Pa. and south; <i>E.&nbsp;cinctiventris</i>, Tex. and Mex.
+<span class="rightalign"><i>Ectrichodia</i>&nbsp;L. et&nbsp;S.</span></p>
+</div>
+
+<p>ff. First segment of the antennæ short. <i>P.&nbsp;æneo-nitens</i>. South
+<span class="rightalign"><i>Pothea</i>&nbsp;A. et&nbsp;S.</span></p>
+</div></div></div>
+
+<p>cc. Ocelli cephalad of the hind margins of the eyes; first segment of the
+antennæ stout, second segment divided into many smaller segments.
+South and west. <i>Homalocoris maculicollis</i>, and <i>Hammatocerus
+purcis</i>. <span class="rightalign"><span class="smcap">Hammatocerinæ</span></span><span class="pagenum"><a name="Page_283" id="Page_283">[Pg 283]</a></span></p>
+</div>
+
+<p>bb. Hemelytra with a quadrangular or discoidal areole in the corium near the
+apex of the clavus (<a href="#Fig_159">fig.&nbsp;159e</a>).</p>
+
+<div class="hanging">
+<p>c. Anal areole of the membrane not extending as far proximad as the costal
+areole; basal segment of the antenna thickened, porrect; the other
+segments slender, folding back beneath the head and the first segment.
+<span class="rightalign"><span class="smcap">Stenopodinæ</span></span></p>
+
+<div class="hanging">
+<p>d. Head armed with a ramous or furcate spine below each side, caudad
+of the eyes.</p>
+
+<div class="hanging">
+<p>e. First segment of the antenna thickened, apex produced in a spine
+beyond the insertion of the second segment. Species from Va.,
+Ill. and south. <span class="rightalign"><i>Pnirontis</i> Stäl.</span></p>
+
+<p>ee. First segment of the antenna not produced beyond the insertion
+of the second segment. <i>Pygolampis</i>, N.&nbsp;E. states and south;
+<i>Gnathobleda</i>, S.&nbsp;W. and Mex.</p>
+</div>
+
+<p>dd. Head unarmed below or armed with a simple spine; rarely with a
+subfurcate spine at the side of the base. Carolina, Missouri and
+south. <i>Stenopoda</i>, <i>Schumannia</i>, <i>Diaditus</i>, <i>Narvesus</i>, <i>Oncocephalus</i></p>
+</div>
+
+<p>cc. Anal areole of membrane extending farther proximad than the costal
+areole.</p>
+
+<div class="hanging">
+<p>d. Ocelli farther apart than the eyes. <i>A.&nbsp;crassipes</i>, widely distributed
+in the United States; other species occur in the southwest.
+<span class="rightalign"><i>Apiomerus</i> Hahn.</span></p>
+
+<p>dd. Ocelli not so far apart as the eyes. <span class="rightalign"><span class="smcap">Zelinæ</span></span></p>
+
+<div class="hanging">
+<p>e. Sides of mesosternum without a tubercle or fold in front.</p>
+
+<div class="hanging">
+<p>f. Fore femur as long as or longer than the hind femur; first segment
+of the beak much shorter than the second. <i>Z.&nbsp;audax</i>, in the
+north eastern states; other species south and west.  <span class="rightalign"><i>Zelus</i> Fabr.</span></p>
+
+<p>ff. Fore femur shorter than the hind femur, rarely of equal length,
+in this case the first segment of the beak as long or longer than
+the second.</p>
+
+<div class="hanging">
+<p>g. First segment of the beak shorter than the second; fore femur
+a little shorter than the hind femur; the first segment of the
+beak distinctly longer than the head before the eyes. <i>P.
+cinctus</i> a widely distributed species (<a href="#Fig_160">fig.&nbsp;160</a>). <i>P.&nbsp;punctipes</i>,
+<i>P.&nbsp;spinicollis</i>, Cal., Mex.      <span class="rightalign">(=&nbsp;<i>Milyas</i>) <i>Pselliopus</i> Berg.</span></p>
+
+<p>gg. First segment of the beak as long or longer than the second.</p>
+
+<div class="hanging">
+<p>h. Pronotum armed with spines on the disc.</p>
+
+<div class="hanging">
+<p>i. Juga distinctly prominent at the apex and often acute or
+subacute; fore femur distinctly thickened; hemelytra
+usually not reaching the apex of the abdomen. <i>Fitchia
+aptera</i>, N.&nbsp;Y., south and west; <i>F.&nbsp;spinosula</i>, South;
+<i>Rocconata annulicornis</i>, Texas, etc.</p>
+
+<p>ii. Juga when prominent, obtuse at apex; eyes full width of
+the head; fore femur not thickened; pronotum with four
+spines on posterior lobe. <i>R.&nbsp;taurus</i>, Pa., south and west
+<span class="rightalign"><i>Repipta</i> Stäl.</span></p>
+</div>
+
+<p>hh. Pronotum unarmed on the disc.<span class="pagenum"><a name="Page_284" id="Page_284">[Pg 284]</a></span></p>
+
+<div class="hanging">
+<p>i. Spines on each apical angle of the penultimate abdominal
+segment. <i>A.&nbsp;cinereus</i>, Pa., and south. <span class="rightalign"><i>Atrachelus</i>&nbsp;A. et&nbsp;S.</span></p>
+
+<p>ii. Apical angle of the penultimate abdominal segment unarmed.
+<i>Fitchia</i> (in part); <i>Castolus ferox</i>, Arizona.</p>
+</div></div></div></div>
+
+<p>ee. Sides of the mesosternum with a <span title="for &quot;tubercle of&quot; read &quot;tubercle or&quot;"><a name="AC_17" id="AC_17"></a>tubercle of</span> fold in front at the hind
+angles of the prosternum; first segment of the beak longer than
+the part of the head cephalad of the eyes.</p>
+
+<div class="hanging">
+<p>f. Fore femur thickened, densely granulated; hind femur unarmed.</p>
+
+<div class="hanging">
+<p>g. Fore tibiæ each with three long spines on the ventral side.
+<i>S.&nbsp;diadema</i> (<a href="#Fig_159">fig.&nbsp;159e</a>), a widely distributed species; and
+several southwestern species.     <span class="rightalign"><i>Sinea</i>&nbsp;A. et&nbsp;S.</span></p>
+
+<p>gg. Fore tibiæ unarmed. <i>A.&nbsp;multispinosa</i>, widely distributed;
+<i>A.&nbsp;tabida</i>, Cal.          <span class="rightalign"><i>Acholla</i> Stäl.</span></p>
+</div>
+
+<p>ff. Fore femur unarmed, rarely a little thickened, a little granulated.</p>
+
+<div class="hanging">
+<p>g. Pronotum produced caudad over the scutellum, with a high
+mesal tuberculate ridge (<a href="#Fig_19">fig.&nbsp;19e</a>). <b>A.&nbsp;cristatus.</b> N.&nbsp;Y. to
+Cal. and south.  <span class="rightalign"><b>Arilus</b> Hahn.</span></p>
+
+<p>gg. Caudal lobe of the pronotum six sided, neither elevated nor
+produced caudad. <i>H.&nbsp;americanus</i>, Southwest; also several
+W.&nbsp;I. and Mexican genera.       <span class="rightalign"><b>Harpactor</b></span></p>
+</div></div></div></div></div></div></div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_161" id="Fig_161"></a>
+<a href="images/f161-full.png"><img src="images/f161.png" width="500" height="357" alt="161. Taxonomic details of Diptera. (a) Ventral aspect of abdomen of Cynomyia;
+(b) antenna of Tabanus; (c) ventral aspect of abdomen of Chortophila; (d)
+ventral aspect of abdomen of Stomoxys; (e) claw of Aedes (Culex) sylvestris,
+male; (f) claw of Hippoboscid; (g) foot of dipterous insect showing
+empodium developed pulvilliform; (h) hind tarsal segment of Simulium
+vittatum, female; (i) foot of dipterous insect showing bristle-like empodium." title="161. Taxonomic details of Diptera. (a) Ventral aspect of abdomen of Cynomyia;
+(b) antenna of Tabanus; (c) ventral aspect of abdomen of Chortophila; (d)
+ventral aspect of abdomen of Stomoxys; (e) claw of Aedes (Culex) sylvestris,
+male; (f) claw of Hippoboscid; (g) foot of dipterous insect showing
+empodium developed pulvilliform; (h) hind tarsal segment of Simulium
+vittatum, female; (i) foot of dipterous insect showing bristle-like empodium." /></a>
+<span class="caption">161. Taxonomic details of Diptera. (<i>a</i>)&nbsp;Ventral aspect of abdomen of Cynomyia;
+(<i>b</i>)&nbsp;antenna of Tabanus; (<i>c</i>)&nbsp;ventral aspect of abdomen of Chortophila;
+(<i>d</i>)&nbsp;ventral aspect of abdomen of Stomoxys; (<i>e</i>)&nbsp;claw of Aedes (Culex) sylvestris,
+male; (<i>f</i>)&nbsp;claw of Hippoboscid; (<i>g</i>)&nbsp;foot of dipterous insect showing
+empodium developed pulvilliform; (<i>h</i>)&nbsp;hind tarsal segment of Simulium
+vittatum, female; (<i>i</i>)&nbsp;foot of dipterous insect showing bristle-like empodium.</span>
+<p><span class="pagenum"><a name="Page_285" id="Page_285">[Pg 285]</a></span></p>
+</div>
+
+
+<h3><a name="DIPTERA_Mosquitoes_Midges_Flies" id="DIPTERA_Mosquitoes_Midges_Flies"></a>DIPTERA (Mosquitoes, Midges, Flies)</h3>
+
+<div class="hanging">
+<p>a. Integument leathery, abdominal segments indistinct; wings often wanting;
+parasitic forms. <span class="rightalign"><b>PUPIPARA</b></span></p>
+
+<div class="hanging">
+<p>b. Head folding back on the dorsum of the thorax; wingless flies parasitic
+on bats. Genus <i>Nycteribia</i>. <span class="rightalign"><span class="smcap">Nycteribiidæ</span></span></p>
+
+<p>bb. Head not folding back upon the dorsum of the thorax; flies either winged
+or wingless; parasitic on birds and on bats and other mammals.</p>
+
+<div class="hanging">
+<p>c. Antennæ reduced, wings when present, with distinct parallel veins and
+outer crossveins; claws simple; palpi leaf-like, projecting in front of
+the head. Flies chiefly found on bats. Several genera occur in North
+America.  <span class="rightalign"><span class="smcap">Streblidæ</span></span></p>
+
+<p>cc. Antennæ more elongate, segments more or less distinctly separated;
+head sunk into an emargination of the thorax; wings when present
+with the veins crowded toward the anterior margin; palpi not leaf-like.
+<span class="rightalign"><span class="smcap"><b>Hippoboscidæ</b></span></span></p>
+
+<div class="hanging">
+<p>d. Wings absent or reduced and not adapted for flight.</p>
+
+<div class="hanging">
+<p>e. Wings and halteres (balancers) absent. <i>M.&nbsp;ovinus</i>, the sheep tick.
+<span class="rightalign"><i>Melophagus</i> Latr.</span></p>
+
+<p>ee. Wing reduced (or cast off), halteres present.</p>
+
+<div class="hanging">
+<p>f. Claw bidentate; ocelli present. On deer after the wings are cast
+off. <i>L.&nbsp;depressa.</i> <span class="rightalign"><i>Lipoptena</i> Nitsch</span></p>
+
+<p>ff. Claw tridentate (<a href="#Fig_161">fig.&nbsp;161&nbsp;f</a>). On <i>Macropis</i>. <i>B.&nbsp;femorata.</i>
+<span class="rightalign"><i>Brachypteromyia</i> Will.</span></p>
+</div></div>
+
+<p>dd. Wings present and adapted for flight.</p>
+
+<div class="hanging">
+<p>e. Claws bidentate.</p>
+
+<div class="hanging">
+<p>f. Ocelli present; head flat; wings frequently cast off. On birds
+before casting of the wing. <span class="rightalign"><i>Lipoptena</i> Nitsch.</span></p>
+
+<p>ff. Ocelli absent; head round; wings present. The horse tick
+<b>H.&nbsp;equina</b> may attack man (<a href="#Fig_162">fig.&nbsp;162</a>). <span class="rightalign"><b>Hippobosca</b> L.</span></p>
+</div>
+
+<p>ee. Claws tridentate (<a href="#Fig_161">fig.&nbsp;161&nbsp;f.</a>).</p>
+
+<div class="hanging">
+<p>f. Anal cell closed at apical margin by the anal crossvein.</p>
+
+<div class="hanging">
+<p>g. Ocelli absent. <span class="rightalign"><i>Stilbometopa</i> Coq.</span></p>
+
+<p>gg. Ocelli present.<span class="pagenum"><a name="Page_286" id="Page_286">[Pg 286]</a></span></p>
+
+<div class="hanging">
+<p>h. R<sub>4+5</sub> does not form an angle at the crossvein. On birds.
+There is a record of one species of this genus attacking man.
+<span class="rightalign"><b>Ornithomyia</b> Latr.</span></p>
+
+<p>hh. R<sub>4+5</sub> makes an angle at the crossvein. <i>O.&nbsp;confluens.</i>
+<span class="rightalign"><i>Ornithoica</i> Rdi.</span></p>
+</div></div>
+
+<p>ff. Anal cell not closed by an anal crossvein. <i>Lynchia</i>, <i>Pseudolfersia</i>,
+and <i>Olfersia</i> are chiefly bird parasites. The first mentioned
+genus is said to be the intermediate host of <i>Hæmoproteus columbæ</i>.</p>
+</div></div></div></div></div>
+
+<p>aa. Abdominal segments chitinous; not parasitic in the adult stage.</p>
+
+<div class="hanging">
+<p>b. Antennæ with six or more segments and empodium not developed pulvilliform;
+palpi often with four segments.</p>
+
+<div class="hanging">
+<p>c. Ocelli present. <span class="smcap"><b>Blepharoceridæ</b></span>, <span class="smcap">Rhyphidæ</span>, <span class="smcap">Bibionidæ</span>, <span class="smcap">Mycetophilidæ</span>,
+besides some isolated genera of other families.</p>
+
+<p>cc. Ocelli absent.</p>
+
+<div class="hanging">
+<p>d. Dorsum of the thorax with a V-shaped suture; wings usually with
+numerous veins; legs often very long and slender. Crane flies.
+<span class="rightalign"><span class="smcap">Tipulidæ</span></span></p>
+
+<p>dd. Dorsum of the thorax without a V-shaped suture.</p>
+
+<div class="hanging">
+<p>e. Not more than four longitudinal veins ending in the wing margin;
+wing usually hairy: antennæ slender; coxæ not long; tibiæ: without
+spurs, legs long and slender. Small, delicate flies often called
+Gall gnats. <span class="rightalign"><span class="smcap">Cecidomyiidæ.</span></span></p>
+
+<p>ee. More than four longitudinal veins ending in the wing margin.</p>
+
+<div class="hanging">
+<p>f. The costal vein is not produced beyond the tip of the wing; radius
+with not more than three branches.</p>
+
+<div class="hanging">
+<p>g. Antennæ short, composed of ten or eleven closely united segments;
+legs stout; body stout; abdomen oval; anterior
+veins stout, posterior ones weak (<a href="#Fig_163">fig.&nbsp;163&nbsp;b</a>); eyes of the male
+contiguous over the antennæ. Black flies, buffalo flies,
+turkey gnats. Many North American species, several of
+them notorious for their blood sucking propensities.
+<span class="rightalign"><span class="smcap"><b>Simuliidæ</b></span></span></p>
+
+<div class="hanging">
+<p>h. Second joint of the hind tarsus with basal scale-like process and
+dorsal excision (<a href="#Fig_161">fig.&nbsp;161&nbsp;h</a>); radial sector not forked; no
+small cell at the base of the wing. <i>S.&nbsp;forbesi</i>, <i>jenningsi</i>,
+<i>johannseni</i>, <i>meridionale</i>, <i>piscicidium</i>, <b>venustum</b>, <b>vittatum</b>,
+etc. Widely distributed species.
+<span class="rightalign">(=&nbsp;<b>Eusimulium</b>) <b>Simulium</b> Latr.</span></p>
+
+<p>hh. No basal scale-like process on the second joint of the hind
+tarsus; radial sector usually forked (<a href="#Fig_163">fig.&nbsp;163&nbsp;b</a>).</p>
+
+<div class="hanging">
+<p>i. Face broad, small basal cell of the wing present. <i>P.&nbsp;fulvum</i>,
+<b>hirtipes</b>, <i>mutatum</i>, <b>pecuarum</b>, <i>pleurale</i>. <span class="rightalign"><b>Prosimulium</b> Roub.</span></p>
+
+<p>ii. Face linear; small basal cell of the wing absent. One
+species, <i>P.&nbsp;furcatum</i>, from California.
+<span class="rightalign"><i>Parasimulium</i> Malloch</span></p>
+</div></div>
+
+<p>gg. Flies of a different structure.</p>
+
+<div class="hanging">
+<p>h. Antennæ composed of apparently two segments and a terminal
+arista formed of a number of closely united segments.
+Rare flies with aquatic larvæ. <span class="rightalign"><span class="smcap">Orphnephilidæ</span></span><span class="pagenum"><a name="Page_287" id="Page_287">[Pg 287]</a></span></p>
+
+<p>hh. Antennæ of six to fifteen segments, those of the male usually
+plumose; legs frequently slender and wings narrow
+<span class="rightalign"><span class="smcap"><b>Chironomidæ</b></span></span></p>
+
+<div class="hanging">
+<p>i. Media forked (except in the European genus <i>Brachypogon</i>);
+thorax without longitudinal fissure and not produced over
+the head (except in four exotic genera); antennæ usually
+fourteen-jointed in both sexes; fore tibia with a simple
+comb of setulæ, hind tibia with two unequal combs,
+middle tibia without comb.  <span class="rightalign"><span class="smcap"><b>Ceratopogoninæ</b></span></span></p>
+
+<div class="hanging">
+<p>j. Thorax produced cap-like over the head, wing narrow
+and very long. <i>Jenkinsia</i>, <i>Macroptilum</i> and <i>Calyptopogon</i>,
+eastern hemisphere; <i>Paryphoconus</i>, Brazil.</p>
+
+<p>jj. Thorax not produced over the head.</p>
+
+<div class="hanging">
+<p>k. Eyes pubescent, empodium well developed, or if short
+then R<sub>2+3</sub> distinct and crossvein-like or the
+branches of&nbsp;R coalescent; r-m crossvein present;
+fore femora not thickened; wing either with appressed
+hairs or with microscopic erect setulæ.
+<span class="rightalign"><i>Dasyhelea</i> Kieff.</span></p>
+
+<p>kk. Eyes bare, or otherwise differing from the foregoing.</p>
+
+<div class="hanging">
+<p>l. Empodium well developed, nearly as long as the
+claws and with long hairs at the base; femora and
+fifth tarsal segments unarmed, i.e.&nbsp;without spines
+or stout setæ; fourth tarsal segment cylindrical.</p>
+
+<div class="hanging">
+<p>m. Wing with erect and microscopic setulæ. Widely
+distributed.
+<span class="rightalign">(=&nbsp;Atrichopogon) <i>Ceratopogon</i> Meig.</span></p>
+
+<p>mm. Wing with long and depressed hairs. Widely
+distributed.  <span class="rightalign"><i>Forcipomyia</i></span></p>
+
+<div class="hanging">
+<p>n. Hind metatarsus shorter or not longer than the
+following (i.e.&nbsp;the second tarsal) segment
+<span class="rightalign">Subgenus <i>Prohelea</i> Kieff</span></p>
+
+<p>nn. Hind metatarsus longer than the following
+segment. <span class="rightalign">Subgenus <i>Forcipomyia</i> Meig.</span></p>
+</div></div>
+
+<p>ll. Empodium short, scarcely reaching the middle of
+the claws, or vestigial.</p>
+
+<div class="hanging">
+<p>m. R-m crossvein wanting.</p>
+
+<div class="hanging">
+<p>n. Palpi four segmented; inferior fork of the media
+obliterated at the base. Australia.
+<span class="rightalign"><i>Leptoconops</i> Skuse</span></p>
+
+<p>nn. Palpi three-segmented.</p>
+
+<div class="hanging">
+<p>o. Legs spinulose, tarsal claws of the female
+with a basal tooth or strong bristle, those
+of the male unequal, the anterior with a
+long sinuous tooth, the posterior with a
+short arcuate tooth. Italy.
+<span class="rightalign"><b>Mycterotypus</b> Noé</span><span class="pagenum"><a name="Page_288" id="Page_288">[Pg 288]</a></span></p>
+
+<p>oo. Legs unarmed; no crossvein between the
+branches of the radius (<a href="#Fig_163">fig.&nbsp;163e</a>). New
+Mexico.  <span class="rightalign"><b>Tersesthes</b> Townsend</span></p>
+</div></div>
+
+<p>mm. R-m crossvein present.</p>
+
+<div class="hanging">
+<p>n. Fore femora very much swollen, armed with
+spines below, fore tibia arcuate and applied
+closely to the inferior margin of the femur.</p>
+
+<div class="hanging">
+<p>o. R<sub>2+3</sub> present, therefore cell R<sub>1</sub> and R<sub>2</sub> both
+present; wing usually fasciate. United
+States. <span class="rightalign"><i>Heteromyia</i> Say.</span></p>
+
+<p>oo. R<sub>2+3</sub> not distinct from R<sub>4+5</sub>, hence cell
+R<sub>3</sub> obliterated. South America.
+<span class="rightalign"><i>Pachyleptus</i> Arrib. (Walker)</span></p>
+</div>
+
+<p>nn. Fore femur not distinctly swollen.</p>
+
+<div class="hanging">
+<p>o. R<sub>2+3</sub> present therefore cells R<sub>1</sub> and R<sub>3</sub>
+both present, or if not, then the branches
+of the radius more or less coalescent,
+obliterating the cells.</p>
+
+<div class="hanging">
+<p>p. At least the tip of the wing with erect
+setulæ; tip of R<sub>4+5</sub> scarcely attaining
+the middle of the wing, empodium rather
+indistinct, not reaching the middle of the
+claws, the claws not toothed, equal, with
+long basal bristle; legs without stout
+setæ. Widely distributed.
+<span class="rightalign"><b>Culicoides</b> Latr.</span></p>
+
+<div class="hanging">
+<p><b>Hæmatomyidium</b> and <b>Oecacta</b> are probable
+synonyms of this.</p>
+</div>
+
+<p>pp. Wings bare, if rarely with hair, then the
+radius reaches beyond two-thirds the
+length of the wing, or the femur or
+fifth tarsal segment with stout black
+spines.</p>
+
+<div class="hanging">
+<p>q. Media unbranched. Europe.
+<span class="rightalign"><i>Brachypogon</i> Kieff</span></p>
+
+<p>qq. Media branched.</p>
+
+<div class="hanging">
+<p>r. Hind femur much swollen and spined.
+America and Europe. <span class="rightalign"><i>Serromyia</i> Meg.</span></p>
+
+<p>rr. Hind femur not distinctly swollen.</p>
+
+<div class="hanging">
+<p>s. Cell R<sub>1</sub> not longer than high; fork
+of the media distad of the crossvein;
+wing with microscopic setulæ.
+<span class="rightalign"><i>Stilobezzia</i> Kieff</span></p>
+
+<p>ss. Cell R<sub>1</sub> elongate.</p>
+
+<div class="hanging">
+<p>t. Femora unarmed. Widely distributed.
+(=&nbsp;Sphaeromias Kieff.
+1913 not Curtis?).
+<span class="rightalign"><b>Johannseniella</b> Will.</span><span class="pagenum"><a name="Page_289" id="Page_289">[Pg 289]</a></span></p>
+
+<p>tt. Femora, at least in part, with
+strong black spines. Widely
+distributed. <span class="rightalign"><i>Palpomyia</i> Megerle</span></p>
+</div></div></div></div></div>
+
+<p>oo. R<sub>2+3</sub> coalescent with R<sub>4+5</sub> hence cell R<sub>3</sub>
+is obliterated.</p>
+
+<div class="hanging">
+<p>p. In the female the lower branch of the
+media with an elbow near its base projecting
+proximad, the petiole of the
+media coalescent with the basal section
+of the radius, wing long and narrow,
+radial sector ending near the tip of the
+wing; venation of the male as in <i>Bezzia</i>;
+front concave. United States.
+<span class="rightalign"><i>Stenoxenus</i> Coq.</span></p>
+
+<p>pp. Venation otherwise, front not concave.</p>
+
+<div class="hanging">
+<p>q. Subcosta and R<sub>1</sub> more or less coalescent
+with the costa; wing pointed at the
+apex, much longer than the body;
+antennæ fourteen segmented, not plumose.
+India. <span class="rightalign"><i>Haasiella</i> Kieff.</span></p>
+
+<p>qq. Subcosta and radius distinct from the
+costa.</p>
+
+<div class="hanging">
+<p>r. Abdomen petiolate. <span class="rightalign"><i>Dibezzia</i> Kieff.</span></p>
+
+<p>rr. Abdomen not petiolate.</p>
+
+<div class="hanging">
+<p>s. Head semi-globose; hind tarsi unusually
+elongate in the female;
+antennæ of the male not plumose.
+Europe. <span class="rightalign"><i>Macropeza</i> Meigen.</span></p>
+
+<p>ss. Head not globose, more or less
+flattened in front; antennæ of
+the male plumose. Widely distributed.
+<span class="rightalign"><i>Bezzia</i> Kieff.</span></p>
+
+<div class="hanging">
+<p>t. Fore femora, at least, armed with
+stout spines below.
+<span class="rightalign">Subgenus <i>Bezzia</i> Kieff.</span></p>
+
+<p>tt. Femora unarmed.
+<span class="rightalign">Subgenus <i>Probezzia</i> Kieff.</span></p>
+</div></div></div></div></div></div></div></div></div></div></div>
+
+<p>ii. Media of the wing simple, and otherwise not as in "i". To
+this group belong numerous Chironomid genera, none of
+which are known to be noxious to man.</p>
+</div></div></div>
+
+<p>ff. The costal vein apparently is continued around the hind margin of
+the wing; radius with at least four branches.</p>
+
+<div class="hanging">
+<p>g. Wing ovate pointed, with numerous veins; crossveins, if evident,
+before the basal third of the wing; veins very hairy;
+very small moth-like flies. <span class="rightalign"><span class="smcap"><b>Psychodidæ</b></span></span></p>
+
+<div class="hanging">
+<p>h. With elongate biting proboscis; the petiole of the anterior
+forked cell of the wing (R<sub>2</sub>) arises at or beyond the middle of
+the wing (<a href="#Fig_163">fig.&nbsp;163d</a>). <span class="rightalign"><b>Phlebotomus</b> Rdi.</span><span class="pagenum"><a name="Page_291" id="Page_291">[Pg 291]</a></span></p>
+
+<p>hh. With shorter proboscis; the petiole of the anterior forked
+cell arises near the base of the wing.
+<span class="rightalign"><i>Psychoda</i>, <i>Pericoma</i>, etc.</span></p>
+</div>
+
+<p>gg. The r-m crossvein placed at or beyond the center of the wing;
+wings not folded roof-like over the abdomen.</p>
+
+<div class="hanging">
+<p>h. Proboscis short, not adapted for piercing; wings bare (<span class="smcap">Dixidæ</span>);
+or wings scaled (<span class="smcap">Culicidæ</span>, Subf. <span class="smcap">Corethrinæ</span>).</p>
+
+<p>hh. Proboscis elongate, adapted for piercing; wings scaled,
+fringed on the hind margin; antennæ of the male bushy
+plumose. Mosquitoes.
+<span class="smcap"><b>Culicidæ</b></span> (exclusive of <span class="smcap">Corethrinæ</span>)</p>
+
+<div class="hanging">
+<p>i. Metanotum without setæ.</p>
+
+<div class="hanging">
+<p>j. Proboscis strongly decurved; body with broad, appressed,
+metalescent scales; cell R<sub>2</sub> less than half as
+long as its petiole; claws of female simple, some of the
+claws of the male toothed. Several large southern
+species believed to feed only on nectar of flowers
+<span class="rightalign"><i>Megarhinus</i> R.&nbsp;D.</span></p>
+
+<p>jj. Proboscis straight or nearly so, or otherwise different.</p>
+
+<div class="hanging">
+<p>k. Scutellum evenly rounded, not lobed; claws simple in
+both sexes.  <span class="rightalign"><b>Anopheles</b> Meig.</span></p>
+
+<div class="hanging">
+<p>l. Abdomen with clusters of broad outstanding scales
+along the sides; outstanding scales on the veins of
+the wing rather narrow, lanceolate; upper side of
+the thorax and scutellum bearing many appressed
+lanceolate scales. Florida and southward (<b>Cellia</b>).</p>
+
+<div class="hanging">
+<p>m. Hind feet from the middle of the second segment
+largely or wholly snow white.</p>
+
+<div class="hanging">
+<p>n. With a black band at the base of the last segment
+of each hind foot.
+<span class="rightalign"><b>A. albimanus</b>*<a name="FNanchor_H_8" id="FNanchor_H_8"></a><a href="#Footnote_H_8" class="fnanchor">[H]</a> and <b>tarsimaculata</b>*</span></p>
+
+<p>nn. Without such a band      <span class="rightalign"><b>A. argyritarsis</b>*</span></p>
+</div>
+
+<p>mm. Hind feet black, mottled with whitish and with
+bands of the same color at the sutures of the
+segments. W.&nbsp;I.  <span class="rightalign"><b>A.&nbsp;maculipes</b></span></p>
+</div>
+
+<p>ll. Abdomen without such a cluster of scales; outstanding
+scales of the wing veins rather narrow, lanceolate;
+tarsi wholly black.</p>
+
+<div class="hanging">
+<p>m. Deep black, thorax obscurely lined with violaceous,
+especially posteriorly; head, abdomen and
+legs black; no markings on the pleura; abdomen
+without trace of lighter bindings;
+wing scales outstanding, uniform, not forming
+spots, though little thicker at the usual points
+indicating the spottings. Florida.  <span class="rightalign"><b>A. atropus</b></span><span class="pagenum"><a name="Page_292" id="Page_292">[Pg 292]</a></span></p>
+
+<p>mm. Otherwise marked when the wings are unspotted.</p>
+
+<div class="hanging">
+<p>n. Wings unspotted.</p>
+
+<div class="hanging">
+<p>o. Petiole of the first forked cell (R<sub>2</sub>) more than a
+third the length of the cell. Mississippi
+valley.  <span class="rightalign"><b>A.&nbsp;walkeri</b></span></p>
+
+<p>oo. Petiole of the first forked cell a third the
+length of the cell. Md.  <span class="rightalign"><b>A.&nbsp;barberi</b></span></p>
+</div>
+
+<p>nn. Wings spotted.</p>
+
+<div class="hanging">
+<p>o. Front margin of the wings with a patch of
+whitish and yellow scales at a point about
+two-thirds or three-fourths of the way from
+base to apex of wing.</p>
+
+<div class="hanging">
+<p>p. Veins of the wing with many broad obovate
+outstanding scales; thorax with a black
+dot near the middle of each side. W.&nbsp;I.
+<span class="rightalign"><b>A.&nbsp;grabhami</b>*</span></p>
+
+<p>pp. The outstanding scales of the wings rather
+narrow, lanceolate.</p>
+
+<div class="hanging">
+<p>q. Scales of the last vein of the wings white,
+those at each end black; R<sub>4+5</sub> black
+scaled, the extreme apex white scaled.
+Widely distributed north and south
+(<a href="#Fig_131">fig.&nbsp;131</a>). <span class="rightalign"><b>A.&nbsp;punctipennis</b></span></p>
+
+<div class="hanging">
+<p>A dark variety from Pennsylvania has
+been named <b>A. perplexens</b>.</p>
+</div>
+
+<p>qq. Scales of the last vein of the wing white,
+those at its apex black; R<sub>4+5</sub> white
+scaled and with two patches of
+black scales. South and the tropics.
+<b>A. franciscanus</b> and <b>pseudopunctipennis</b>*</p>
+</div></div>
+
+<p>oo. Front margin of the wings wholly black
+scaled.</p>
+
+<div class="hanging">
+<p>p. Last (anal) vein of the wings white scaled
+with three patches of black scales (<a href="#Fig_132">fig.&nbsp;132</a>).
+New Jersey to Texas. <span class="rightalign"><b>A. crucians</b>*</span></p>
+
+<p>pp. Last vein of the wings wholly black
+scaled.</p>
+
+<div class="hanging">
+<p>q. Widely distributed north and south
+(<a href="#Fig_130">fig.&nbsp;130</a>), (=&nbsp;<b>maculipennis</b>).
+<span class="rightalign"><b>A.&nbsp;quadrimaculatus</b>*</span></p>
+
+<p>qq. Distributed from Rocky Mountains
+westward.  <span class="rightalign"><b>A.&nbsp;occidentalis</b></span></p>
+</div></div></div></div></div></div>
+
+<p>kk. Scutellum distinctly trilobed.</p>
+
+<div class="hanging">
+<p>l. Cell R<sub>2</sub> less than half as long as its petiole; thorax
+with metallic blue scales; median lobe of the
+scutellum not tuberculate; few small species which
+are not common.  <span class="rightalign"><b>Uranotænia</b> Arrib.</span><span class="pagenum"><a name="Page_293" id="Page_293">[Pg 293]</a></span></p>
+
+<p>ll. Cell R<sub>2</sub> nearly or quite as long as its petiole, or
+otherwise distinct.</p>
+
+<div class="hanging">
+<p>m. Femora with erect outstanding scales; occiput
+broad and exposed. Large species. <b>P.&nbsp;ciliata.</b>
+<b>P.&nbsp;howardi.</b>  <span class="rightalign"><b>Psorophora</b> R.&nbsp;D.</span></p>
+
+<p>mm. Femora without erect scales.</p>
+
+<div class="hanging">
+<p>n. Clypeus bearing several scales or hairs, scutellum
+with broad scales only; back of head
+with broad scales; scales along the sides of the
+mesonotum narrow; some or the claws
+toothed; thorax marked with a pair of
+silvery scaled curved stripes; legs black
+with white bands at the bases of some of the
+segments (<a href="#Fig_134">fig.&nbsp;134</a>). Yellow Fever mosquito
+<span class="rightalign"><b>Aedes</b> (=&nbsp;<b>Stegomyia</b>) <b>calopus</b>.</span></p>
+
+<p>nn. With another combination of characters.
+Numerous species of mosquitoes belonging
+to several closely related genera, widely
+distributed over the country. (<i>Culex</i>, <i>Aedes</i>,
+<i>Ochlerotatus</i>, etc.). <b>Culex</b> in the wide sense.</p>
+</div></div></div></div></div>
+
+<p>ii. Metanotum with setæ. <i>Wyeomyia</i> (found in the United
+States); and related tropic genera.</p>
+</div></div></div></div></div></div></div>
+
+<p>bb. Antennæ composed of three segments with a differentiated style or bristle;
+third segment sometimes complex or annulate, in which case the empodium
+is usually developed like the pulvilli, i.e., pad-like (<a href="#Fig_161">fig.&nbsp;161&nbsp;g</a>).</p>
+
+<div class="hanging">
+<p>c. Empodium developed pad-like (pulvilliform) i.e., three nearly equal
+membranous appendages on the underside of the claw (<a href="#Fig_161">fig.&nbsp;161g</a>).</p>
+
+<div class="hanging">
+<p>d. Squamæ, head, and eyes large; occiput flattened or concave; third
+segment of the antennæ with four to eight annuli or segments,
+proboscis adapted for piercing; body with fine hairs, never with
+bristles; middle tibia with two spurs; wing venation as figured
+(<a href="#Fig_163">fig.&nbsp;163f</a>); marginal vein encompasses the entire wing. Horse
+flies, greenheads, deer flies, gad flies.  <span class="rightalign"><span class="smcap"><b>Tabanidæ</b></span><a name="FNanchor_I_9" id="FNanchor_I_9"></a><a href="#Footnote_I_9" class="fnanchor">[I]</a></span></p>
+
+<div class="hanging">
+<p>e. Hind tibia with spurs at tip; ocelli usually present. (<span class="smcap"><b>Pangoninæ</b></span>)</p>
+
+<div class="hanging">
+<p>f. Third joint of the antennæ with seven or eight segments; proboscis
+usually prolonged.</p>
+
+<div class="hanging">
+<p>g. Each section the third antennal segment branched. Central
+American species, <i>P.&nbsp;festæ</i>.  <span class="rightalign"><i>Pityocera</i> G.&nbsp;T.</span></p>
+
+<p>gg. Sections of the third antennal segment not branched.</p>
+
+<div class="hanging">
+<p>h. Upper corner of the eyes in the female terminating in an acute
+angle; wings of both sexes dark anteriorly. <i>G.&nbsp;chrysocoma</i>,
+a species from the eastern states.  <span class="rightalign"><i>Goniops</i> Ald.</span></p>
+
+<p>hh. Upper corner of the eye in the female not so terminating;
+wings nearly uniform in color, or hyaline.</p>
+
+<div class="hanging">
+<p>i. Proboscis scarcely extending beyond the palpi; front of the
+female wide; much wider below than above. S.&nbsp;W.
+States.  <span class="rightalign"><i>Apatolestes</i> Will.</span><span class="pagenum"><a name="Page_294" id="Page_294">[Pg 294]</a></span></p>
+
+<p>ii. Proboscis extending beyond the palpi.</p>
+
+<div class="hanging">
+<p>j. Wing with cell M<sub>3</sub> closed. Tropic America.
+<span class="rightalign">(=&nbsp;<i>Diclisa</i>) <i>Scione</i> Wlk.</span></p>
+
+<p>jj. Cell M<sub>3</sub> open; ocelli present or absent. Two or three
+eastern species; many south and west.       <span class="rightalign"><b>Pangonia</b> Rdi.</span></p>
+</div></div></div></div>
+
+<p>ff. Third segment of the antenna with five divisions; ocelli present.</p>
+
+<div class="hanging">
+<p>g. First and second segments of the antenna short, the second only
+half as long as the first, three western species.  <span class="rightalign"><b>Silvius</b> Rdi.</span></p>
+
+<p>gg. First and second segments of the antenna long, the second
+distinctly over half as long as the first. Deer flies. Many
+species, widely distributed.  <span class="rightalign"><b>Chrysops</b> Meig.</span></p>
+</div></div>
+
+<p>ee. Hind tibia without spurs; ocelli absent.</p>
+
+<div class="hanging">
+<p>f. Third segment of antenna with four divisions, no tooth or angulation;
+wings marked with rings and circles of darker coloring;
+front of the female very wide. Widely distributed. <i>H.&nbsp;americana</i>,
+<i>H.&nbsp;punctulata</i>.        <span class="rightalign"><b>Hæmatopota</b> Meig.</span></p>
+
+<p>ff. Third segment of the antenna with five divisions (<a href="#Fig_161">fig.&nbsp;161b</a>).</p>
+
+<div class="hanging">
+<p>g. Third segment of the antenna not furnished with a tooth or
+distinct angular projection.</p>
+
+<div class="hanging">
+<p>h. Body covered with metallic scales; front of female of normal
+width; front and middle tibiæ greatly dilated. <i>L.
+lepidota</i>.   <span class="rightalign"><i>Lepidoselaga</i> Macq.</span></p>
+
+<p>hh. Body without metallic scales; antennæ not very long, the
+third segment not cylindrical, not situated on a projecting
+tubercle; front of the female narrow. South. <i>D.&nbsp;ferrugatus.</i>
+<span class="rightalign">(=&nbsp;<i>Diabasis</i>) <i>Diachlorus</i> O.&nbsp;S.</span></p>
+</div>
+
+<p>gg. Third segment of the antenna furnished with a tooth or a
+distinct angular projection.</p>
+
+<div class="hanging">
+<p>h. Hind tibiæ ciliate with long hairs. S.&nbsp;W. and tropics.
+<span class="rightalign"><i>Snowiella</i> and <i>Stibasoma</i>.</span></p>
+
+<p>hh. Hind tibiæ not ciliate.</p>
+
+<div class="hanging">
+<p>i. Species of slender build, usually with a banded thorax and
+abdomen; third segment of the antenna slender, the
+basal prominence long; wings mostly with brownish
+markings. Tropic America.        <span class="rightalign"><i>Dichelacera</i> Macq.</span></p>
+
+<p>ii. Species of a stouter build; third segment of the antenna
+stout, its basal process short (<a href="#Fig_161">fig.&nbsp;161b</a>). Many species,
+widely distributed       <span class="rightalign"><b>Tabanus</b> L.</span></p>
+</div></div></div></div></div>
+
+<p>dd. With another group of characters.</p>
+
+<div class="hanging">
+<p>e. Squamæ small, antennæ variable, thinly pilose or nearly bare species,
+without distinct bristles; wing veins not crowded anteriorly, R<sub>4</sub> and
+R<sub>5</sub> both present, basal cells large; middle tibiæ at least with spurs.
+<span class="rightalign"><span class="smcap"><b>Leptidæ</b></span></span></p>
+
+<div class="hanging">
+<p>f. Flagellum of the antenna more or less elongated, composed of
+numerous more or less distinct divisions.
+<span class="rightalign"><span class="smcap">Xylophaginæ</span> and <span class="smcap">Arthroceratinæ</span>.</span></p>
+
+<p>ff. Antennæ short, third segment simple, with arista or style; face
+small, proboscis short  <span class="rightalign"><span class="smcap"><b>Leptinæ</b></span></span><span class="pagenum"><a name="Page_295" id="Page_295">[Pg 295]</a></span></p>
+
+<div class="hanging">
+<p>g. Front tibiæ each with one or two spurs, or if absent, then no
+discal cell. <i>Triptotricha</i>, <i>Pheneus</i>, <i>Dialysis</i>, <i>Hilarimorpha</i>.</p>
+
+<p>gg. Front tibiæ without terminal spurs, discal cell present.</p>
+
+<div class="hanging">
+<p>h. Hind tibiæ each with a single spur.</p>
+
+<div class="hanging">
+<p>i. Anal cell open (<a href="#Fig_163">fig.&nbsp;163g</a>); third antennal segment kidney-shaped
+with dorsal or subdorsal arista; first antennal
+segment elongate and thickened. About a dozen species
+have been described from the United States, of which at
+least one (<b>S.&nbsp;pachyceras</b>) is known to be a vicious blood
+sucker.        <span class="rightalign"><b>Symphoromyia</b> Frauenf.</span></p>
+
+<p>ii. Anal cell closed; third antennal segment not kidney-shaped.
+<i>Chrysopila</i>, <i>Ptiolina</i>, <i>Spania</i>.</p>
+</div>
+
+<p>hh. Hind tibiæ each with two spurs.</p>
+
+<div class="hanging">
+<p>i. Third segment kidney-shaped, the arista subdorsal; anal
+cell closed.        <span class="rightalign"><i>Atherix</i> Meig.</span></p>
+
+<p>ii. Third segment of the antenna short and with terminal
+arista; anal cell open.        <span class="rightalign"><i>Leptis</i> Fabr.</span></p>
+
+<div class="hanging">
+<p>Two European species of this genus have been accused of
+blood sucking habits, but the record seems to have
+been based upon error in observation.</p>
+</div></div></div></div></div>
+
+<p>ee. With another combination of characters.
+<span class="rightalign"><span class="smcap">Stratiomyiidæ</span>, <span class="smcap">Cyrtidæ</span>, etc.</span></p>
+</div></div>
+
+<p>cc. Empodium bristlelike or absent.</p>
+
+<div class="hanging">
+<p>d. Antennæ apparently two segmented, with three-segmented arista,
+wings (rarely wanting) with several stout veins anteriorly, the
+weaker ones running obliquely across the wing (<a href="#Fig_163">fig.&nbsp;163h</a>); small,
+quick running, bristly, humpbacked flies. Several genera; <b>Aphiochæta</b>,
+<b>Phora</b>, <b>Trineura</b>, etc.        <span class="rightalign"><span class="smcap"><b>Phoridæ</b></span></span></p>
+
+<p>dd. Flies with other characters.</p>
+
+<div class="hanging">
+<p>e. No frontal lunule above the base of the antennæ; both R<sub>4</sub> and R<sub>5</sub>
+often present; third segment of the antenna often with a terminal
+bristle. <span class="smcap"><b>Asilidæ</b></span>, <span class="smcap">Mydaidæ</span>, <span class="smcap">Apioceridæ</span>, <span class="smcap">Therevidæ</span>, <span class="smcap">Scenopinidæ</span>,
+<span class="smcap">Bombyliidæ</span>, <span class="smcap">Empididæ</span>, <span class="smcap">Dolichopodidæ</span>, <span class="smcap">Lonchopteridæ</span>.</p>
+
+<p>ee. A frontal lunule above the base of the antennæ; third segment of the
+antenna always simple, i.e., not ringed, usually with a dorsal
+arista; R<sub>4</sub> and R<sub>5</sub> coalesced into a simple vein.</p>
+
+<div class="hanging">
+<p>f. A spurious vein or fold between the radius and the media, rarely
+absent; the cell R<sub>4+5</sub> closed at the apex by vein M<sub>1</sub>; few or no
+bristles on the body, none on the head; flies frequently with
+yellow markings. <b>Eristalis</b> (<a href="#Fig_163">fig.&nbsp;163i</a>), <b>Helophilus</b>, and many
+other genera.        <span class="rightalign"><span class="smcap"><b>Syrphidæ</b></span></span></p>
+
+<p>ff. No spurious vein present.</p>
+
+<div class="hanging">
+<p>g. Body without bristles; proboscis elongate and slender, often
+folding; front of both male and female broad.        <span class="rightalign"><span class="smcap">Conopidæ</span></span></p>
+
+<p>gg. Bristles almost always present on head, thorax, abdomen and
+legs.<span class="pagenum"><a name="Page_296" id="Page_296">[Pg 296]</a></span></p>
+
+<div class="hanging">
+<p>h. Arista terminal; hind metatarsus enlarged, sometimes ornamented,
+hind tarsus more or less flattened beneath.
+<span class="rightalign"><span class="smcap">Platypezidæ</span></span></p>
+
+<p>hh. Flies having a different combination of characters.</p>
+
+<div class="hanging">
+<p>i. Head large, eyes occupying nearly the entire head; cell
+R<sub>4+5</sub> narrowed in the margin; small flies.       <span class="rightalign"><span class="smcap">Pipunculidæ</span></span></p>
+
+<p>ii. Head and eyes not unusually large.</p>
+
+<div class="hanging">
+<p>j. Squamæ (tegulæ, or calyptræ, or alulæ) not large, often
+quite small, the lower one lacking, or at most barely
+projecting from below the upper one (antisquama);
+front of both male and female broad, the eyes therefore
+widely separated; posthumeral and intraalar macrochæta
+not simultaneously present; thorax usually
+without a complete transverse suture; postalar callus
+usually absent; the connectiva adjoining the ventral
+sclerites always visible; hypopleural macrochætæ
+absent; last section of R<sub>4+5</sub> and M<sub>1+2</sub> with but few
+exceptions nearly parallel; subcostal vein often wanting
+or vestigial or closely approximated to R<sub>1</sub>; the latter
+often short, basal cells small, the posterior ones often
+indistinct or wanting; vibrissæ present or absent
+<span class="rightalign"><span class="smcap"><b>Acalyptrate Muscoidea</b></span></span></p>
+
+<div class="hanging">
+<p>k. Subcosta present, distinctly separated from R<sub>1</sub> at the
+tip; R<sub>1</sub> usually ends distad of the middle of the
+wing; the small basal cells of the wing distinct.</p>
+
+<div class="hanging">
+<p>l. A bristle (vibrissa) on each side of the face near the
+margin of the mouth.   <span class="smcap"><b>Cordyluridæ</b></span>, <span class="smcap"><b>Sepsidæ</b></span>,
+<span class="smcap">Phycodromidæ</span>, <span class="smcap">Heteroneuridæ</span>, <span class="smcap">Helomyzidæ</span>.</p>
+
+<p>ll. No vibrissæ present.</p>
+
+<div class="hanging">
+<p>m. Head nearly spherical, cheeks broad and retreating;
+proboscis short; the cell R<sub>5</sub> closed or
+narrowed in the margin; legs very long; tarsi
+shorter than the tibiæ. <b>Calobata</b> and other
+genera.        <span class="rightalign"><span class="smcap"><b>Micropezidæ</b></span></span></p>
+
+<p>mm. Flies with another combination of characters.
+<span class="smcap">Rhopalomeridæ</span>, <span class="smcap">Trypetidæ</span>, <span class="smcap">Ortalidæ</span>,
+<span class="smcap">Sciomyzidæ</span>.</p>
+</div></div>
+
+<p>kk. Subcosta absent or vestigial, or if present, then
+apparently ending in the costa at the point where
+R<sub>1</sub> joins it; R<sub>1</sub> usually ends in the costa at or before
+the middle of the wing.</p>
+
+<div class="hanging">
+<p>l. Arista long plumose, or pectinate above; oral vibrissæ
+present; anal cell complete; costa broken at
+the apex of R<sub>1</sub>. <b>Drosophila</b>, <b>Phortica</b>, and other
+genera.        <span class="rightalign"><span class="smcap"><b>Drosophilidæ</b></span></span></p>
+
+<p>ll. With another combination of characters.</p>
+
+<div class="hanging">
+<p>m. The cell M and first M<sub>2</sub> not separated by a crossvein;
+anal cell absent; front bare or only<span class="pagenum"><a name="Page_297" id="Page_297">[Pg 297]</a></span>
+bristly above; usually light colored flies.
+<b>Hippelates</b>, <b>Oscinus</b>, and other genera. (See
+also m&nbsp;m&nbsp;m.)         <span class="rightalign"><span class="smcap"><b>Oscinidæ</b></span></span></p>
+
+<p>mm. Cell M and cell first M<sub>2</sub> often separated by a
+crossvein; anal cell present, complete, though
+frequently small; scutellum without spines
+or protuberances; oral vibrissæ present;
+arista bare or short plumose; front bristly at
+vertex only; small dark flies. <b>Piophila</b>
+(<a href="#Fig_99">fig.&nbsp;99</a>), <b>Sepsis</b> and other genera.         <span class="rightalign"><span class="smcap"><b>Sepsidæ</b></span></span></p>
+
+<p>mmm. The <span class="smcap">Geomyzidæ</span>, <span class="smcap">Agromyzidæ</span>, <span class="smcap">Psilidæ</span>,
+<span class="smcap">Trypetidæ</span>, <span class="smcap">Rhopalomeridæ</span>, <span class="smcap">Borboridæ</span>
+and <span class="smcap">Diopsidæ</span> differ in various particulars
+from either the <span class="smcap"><b>Oscinidæ</b></span> and the <span class="smcap"><b>Sepsidæ</b></span>
+noted above.</p>
+</div></div></div>
+
+<p>jj. Squamæ well developed, usually large, the lower one
+frequently projecting from below the upper one; both
+posthumeral and intraalar macrochætæ present;
+thorax with a complete transverse suture; postalar
+callus present and separated by a distinct suture from
+the dorsum of the thorax; front of the female broad,
+of the male frequently narrow, the eyes then nearly or
+quite contiguous; the connectiva adjoining the ventral
+sclerites either visible or not; hypopleural macrochætæ
+present or absent; subcosta always distinct in
+its whole course, R<sub>1</sub> never short.         <span class="rightalign"><span class="smcap"><b>Calyptrate Muscoidea</b></span><a name="FNanchor_J_10" id="FNanchor_J_10"></a><a href="#Footnote_J_10" class="fnanchor">[J]</a></span></p>
+</div>
+
+<p>k. Oral opening small, mouth parts usually much reduced
+or vestigial. This family is undoubtedly of polyphyletic
+origin but for convenience it is here considered
+as a single family.         <span class="rightalign"><span class="smcap"><b>Oestridæ.</b></span></span></p>
+
+<div class="hanging">
+<p>l. The costal vein ends at the tip of R<sub>4+5</sub>, M<sub>1+2</sub>
+straight, not reaching the wing margin, hence
+cell R<sub>5</sub> wide open (<a href="#Fig_163">fig.&nbsp;163j</a>); squamæ small;
+arista bare; ovipositor of the female elongate.
+Larvæ in the alimentary canal of horses, etc.         <span class="rightalign"><b>Gastrophilus</b></span></p>
+
+<div class="hanging">
+<p>m. Posterior crossvein (m-cu) wanting; wings
+smoky or with clouds. Europe.         <span class="rightalign"><b>G. pecorum</b></span></p>
+
+<p>mm. Posterior crossvein (m-cu) present, at least in
+part.<span class="pagenum"><a name="Page_298" id="Page_298">[Pg 298]</a></span></p>
+
+<div class="hanging">
+<p>n. Wing hyaline with smoky median cross band,
+and two or three spots; posterior trochanters
+with hook in the male and a prominence in
+the female. World wide distribution.         <span class="rightalign"><b>G. equi.</b></span></p>
+
+<p>nn. Wings without spots.</p>
+
+<div class="hanging">
+<p>o. Posterior crossvein (m-cu) distad of the
+anterior crossvein (r-m); legs, particularly
+the femora, blackish brown. Europe and
+North America.         <span class="rightalign"><b>G. hæmorrhoidalis</b></span></p>
+
+<p>oo. Posterior crossvein opposite or proximad of
+the anterior crossvein. Europe and North
+America.         <span class="rightalign"><b>G. nasalis</b></span></p>
+</div></div></div>
+
+<p>ll. The costal vein ends at the tip of M<sub>1+2</sub>, M<sub>1+2</sub> with a
+bend, the cell R<sub>5</sub> hence much narrowed in the
+margin, or closed.</p>
+
+<div class="hanging">
+<p>m. Proboscis geniculate, inserted in a deep slit;
+female without extricate ovipositor; arista
+either bare or plumose; squamæ large; facial
+grooves approximated below.</p>
+
+<div class="hanging">
+<p>n. Arista bare, short. Larvæ in rodents. Tropic
+America. <i>B.&nbsp;princeps</i>.         <span class="rightalign"><i>Bogeria</i> Austen</span></p>
+
+<p>nn. Arista pectinate above.</p>
+
+<div class="hanging">
+<p>o. Tarsi broadened and flattened, hairy, anal
+lobe of the wing large. Larvæ in rodents.
+A number of American species. <span class="rightalign"><i>Cuterebra.</i></span></p>
+
+<p>oo. Tarsi slender, not hairy; anal lobe of the
+wing moderate. Larvæ in man and other
+mammals. Tropic America. <b>D.&nbsp;cyaniventris.</b>
+<span class="rightalign"><b>Dermatobia</b> Br.</span></p>
+</div></div>
+
+<p>mm. Mouth parts very small, vestigial; arista bare.</p>
+
+<div class="hanging">
+<p>n. Facial grooves approximated below, leaving a
+narrow median depression or groove.</p>
+
+<div class="hanging">
+<p>o. Cell R<sub>5</sub> closed and petiolate, body nearly
+bare. Larvæ in the nasal cavities of the
+smaller Ungulates. The sheep bot fly.
+<b>O.&nbsp;ovis.</b> Widely distributed          <span class="rightalign"><b>Oestrus</b> L.</span></p>
+
+<p>oo. Cell R<sub>5</sub> narrowly open, body hairy. Larvæ
+parasitic on deer. Europe and America.         <span class="rightalign"><i>Cephenomyia</i> Latr.</span></p>
+</div>
+
+<p>nn. Facial grooves far apart, enclosing between
+them a broad shield-shaped surface; squamæ
+large; female with elongate ovipositor.
+Larvæ hypodermatic on Ungulates.         <span class="rightalign"><b>Hypoderma</b> Clark</span></p>
+
+<div class="hanging">
+<p>o. Palpi wanting; tibiæ thickened in the middle.</p>
+
+<div class="hanging">
+<p>p. Hair at apex of the abdomen yellow; legs
+including femora yellowish brown.         <span class="rightalign"><b>H.&nbsp;diana</b></span><span class="pagenum"><a name="Page_299" id="Page_299">[Pg 299]</a></span></p>
+
+<p>pp. Hair at the apex of the abdomen reddish
+yellow. Europe and America.</p>
+
+<div class="hanging">
+<p>q. Tibiæ and tarsi yellow; femora black.         <span class="rightalign"><b>H.&nbsp;lineata</b></span></p>
+
+<p>qq. Legs black with black hair; tips of
+hind tibia and tarsi yellowish brown.         <span class="rightalign"><b>H.&nbsp;bovis</b></span></p>
+</div></div>
+
+<p>oo. Palpi small, globular; tibiæ cylindrical,
+straight. On reindeer. <i>O.&nbsp;tarandi</i>
+<span class="rightalign"><i>Oedemagena</i> Latr.</span></p>
+</div></div></div></div>
+
+<p>kk. Oral opening of the usual size; mouth parts not
+vestigial.</p>
+
+<div class="hanging">
+<p>l. Hypopleurals wanting; if three sternopleurals are
+present the arrangement is 1:2; conjunctiva
+(<a href="#Fig_161">fig.&nbsp;161c</a>) of the venter usually present; if the
+terminal section of M<sub>1+2</sub> is bent it has neither fold
+nor appendage. (<span class="smcap"><b>Anthomyiidæ</b></span> of Girschner).</p>
+
+<div class="hanging">
+<p>m. Sternopleurals wanting; M<sub>1+2</sub> straight toward
+the apex, costa ends at or slightly beyond the
+tip of R<sub>4+5</sub>; mouth parts vestigial.
+<span class="rightalign"><span class="smcap"><b>Gastrophilinæ.</b></span> See <span class="smcap"><b>Oestridæ</b></span></span></p>
+
+<p>mm. Sternopleurals present, if rarely absent then
+differing in other characters.</p>
+
+<div class="hanging">
+<p>n. Caudal margin of the fifth ventral abdominal
+sclerite of the male deeply notched on the
+median line usually to beyond the middle;
+abdomen often cylindrical or linear; abdomen
+often with four to eight spots; eyes of the
+male usually widely separated; sternopleurals
+three, arranged in an equilateral
+triangle; subapical seta of the hind tibia
+placed very low; M<sub>1+2</sub> straight; anal vein
+abbreviated; wings not rilled. <i>Cænosia</i>,
+<i>Caricea</i>, <i>Dexiopsis</i>, <i>Hoplogaster</i>, <i>Sch&oelig;nomyia</i>,
+etc. (<span class="smcap">C&oelig;nosinæ</span>)<a name="FNanchor_K_11" id="FNanchor_K_11"></a><a href="#Footnote_K_11" class="fnanchor">[K]</a>.
+<span class="rightalign"><span class="smcap">Anthomyiidæ</span> in part</span></p>
+
+<p>nn. Caudal margin of the fifth ventral abdominal
+sclerite of the male incurved, rarely deeply
+cleft, rarely entire, in a few genera
+deeply two or three notched; M<sub>1+2</sub> straight<span class="pagenum"><a name="Page_300" id="Page_300">[Pg 300]</a></span>
+or curved; abdomen usually short or elongate
+oval; sternopleurals, if three are present,
+arranged in the order 1:2 in a right triangle.
+<span class="rightalign">(<span class="smcap">Muscinæ-Anthomyiinæ</span> of Girschner)</span></p>
+
+<div class="hanging">
+<p>o. M<sub>1+2</sub> straight, hence cell R<sub>5</sub> not narrowed in
+the margin.  <span class="rightalign"><span class="smcap"><b>Anthomyiidæ</b></span> in part</span></p>
+
+<div class="hanging">
+<p>p. Underside of the scutellum more or less
+sparsely covered with fine hairs; anal
+vein nearly always reaches the hind
+margin of the wing; extensor surface of
+the hind tibiæ with a number of stout
+setæ; squamæ often small and equal.
+<b>Anthomyia</b>, <i>Chortophila</i>, <i>Eustalomyia</i>,
+<i>Hammomyia</i>, <i>Hylemyia</i>, <i>Prosalpia</i>, <i>Pegomyia</i>,
+etc.        <span class="rightalign"><span class="smcap"><b>Hylemyinæ-Pegomyinæ</b></span></span></p>
+
+<p>pp. Underside of the scutellum bare; anal
+vein does not reach the wing margin.</p>
+
+<div class="hanging">
+<p>q. First anal vein short, second anal suddenly
+flexed upwards; hind tibiæ each
+with one or two strong setæ on the
+extensor surface. <b>Fannia</b> (=&nbsp;<b>Homalomyia</b>),
+<i>C&oelig;lomyia</i>, <i>Choristoma</i>, <i>Euryomma</i>,
+<i>Azelia</i>, etc. <span class="rightalign"><span class="smcap"><b>Fanninæ-Azelinæ</b></span></span></p>
+
+<p>qq. Anal veins parallel or divergent.</p>
+
+<div class="hanging">
+<p>r. Setæ on the exterior surface of the hind
+tibiæ wanting (except in <i>Limnaricia</i>
+and <i>C&oelig;nosites</i>), lower squama not
+broadened to the margin of the
+scutellum. <i>Leucomelina</i>, <i>Limnophora</i>,
+<i>Limnospila</i>, <i>Lispa</i>, <i>Mydæa</i>,
+<i>Spilogaster</i>, etc.       <span class="rightalign"><span class="smcap">Mydæinæ-Limnophorinæ</span></span></p>
+
+<p>rr. One (rarely more) seta on the extensor
+surface of the hind tibia; squamæ
+usually large and unequal. <b>Hydrotaea</b>,
+<i>Aricia</i>, <i>Drymeia</i>, <i>Ophyra</i>,
+<i>Phaonia</i> (= <i>Hyetodesia</i>), <i>Pogonomyia</i>,
+<i>Trichophthicus</i>, etc. <span class="rightalign"><span class="smcap"><b>Aricinæ</b></span></span></p>
+</div></div></div>
+
+<p>oo. M<sub>1+2</sub> curved or bent, hence the cell R<sub>5</sub> more
+or less narrowed in  the margin.
+(<span class="smcap"><b>Muscinæ</b></span>). <span class="smcap"><b>Muscidæ</b></span> in part. See
+<a href="#Page_303">page 303</a> for generic synopsis.</p>
+</div></div></div>
+
+<p>ll. Hypopleurals present; when three sternopleurals
+are present the arrangement is 2:1 or 1:1:1.
+<span class="rightalign">(<span class="smcap">Tachinidæ</span> of Girschner)</span></p>
+
+<div class="hanging">
+<p>m. Conjunctiva of the ventral sclerites of the abdomen
+present, frequently well developed,
+surrounding the sclerites.<span class="pagenum"><a name="Page_301" id="Page_301">[Pg 301]</a></span></p>
+
+<div class="hanging">
+<p>n. Mouth parts vestigial. <span class="smcap"><b>Oestridæ.</b></span> See <a href="#Page_297">page
+297</a> for generic synopsis.</p>
+
+<p>nn. Mouth parts well developed.</p>
+
+<div class="hanging">
+<p>o. M<sub>1+2</sub> straight, hence cell R<sub>5</sub> wide open in
+the margin; costa ending at the tip of R<sub>5</sub>;
+three sternopleurals present; antennal
+arista plumose. <i>Syllegoptera</i>.  Europe.
+(<span class="smcap">Syllegopterinæ</span>). <span class="rightalign"><span class="smcap">Dexiidæ</span> in part</span></p>
+
+<p>oo. M<sub>1+2</sub> bent, hence cell R<sub>5</sub> narrowed in the
+margin; sternopleurals rarely wanting,
+usually 1:1 or 0:1; facial plate strongly
+produced below vibrissal angle like the
+bridge of the nose; antennal arista bare.
+Parasitic on Hemiptera and Coleoptera.
+<i>Allophora</i>, <i>Cistogaster</i>, <i>Clytia</i>, <i>Phasia</i>,
+etc. (<span class="smcap">Phasiinæ</span>).        <span class="rightalign"><span class="smcap">Tachinidæ</span> in part.</span></p>
+</div></div>
+
+<p>mm. Conjunctiva of the ventral sclerites invisible
+(<a href="#Fig_161">fig.&nbsp;161a</a>).</p>
+
+<div class="hanging">
+<p>n. Second ventral sclerite of the abdomen lying
+with its edges either upon or in contact with
+the ventral edges of the corresponding
+dorsal sclerite.</p>
+
+<div class="hanging">
+<p>o. Outermost posthumeral almost always lower
+(more ventrad) in position than the presutural
+macrochæta; fifth ventral abdominal
+sclerite of the male cleft beyond the
+middle, often strongly developed; body
+color very frequently metallic green or
+blue, or yellow; arista plumose. (<span class="smcap"><b>Calliphorinæ</b></span>)
+<span class="rightalign"><span class="smcap"><b>Muscidæ</b></span> in part.</span></p>
+
+<div class="hanging">
+<p>See <a href="#Page_303">page 303</a> for generic synopsis.</p>
+</div>
+
+<p>oo. Outermost posthumeral macrochæta on
+level or higher (more dorsad) than the
+presutural macrochæta; arista bare, pubescent,
+or plumose only on the basal two-thirds;
+body coloring usually grayish
+(<a href="#Fig_106">fig.&nbsp;106</a>).        <span class="rightalign"><span class="smcap"><b>Sarcophagidæ</b></span></span></p>
+
+<div class="hanging">
+<p>p. Fifth ventral sclerite of the male either
+wanting or with the caudal margin
+straight; presutural intraalar rarely
+present.  <span class="rightalign">(<span class="smcap"><b>Sarcophaginæ</b></span>)</span></p>
+
+<div class="hanging">
+<p>q. Fifth ventral abdominal sclerite of the
+male much reduced, the remaining
+segments with straight posterior margin,
+overlapping scale-like; in the
+female only segment one and two scale-like,
+the others wholly or in part
+covered; sternopleurals usually three
+or more. <b>Sarcophaga</b> and related
+genera.<span class="pagenum"><a name="Page_302" id="Page_302">[Pg 302]</a></span></p>
+
+<p>qq. Fifth ventral sclerite of the male plainly
+visible; sternopleurals usually two.
+<b>Sarcophila</b>, <b>Wohlfahrtia</b>, <i>Brachycoma</i>,
+<i>Hilarella</i>, <i>Miltogramma</i>, <i>Metopia</i>,
+<i>Macronychia</i>, <i>Nyctia</i>, <i>Paramacronychia</i>,
+<i>Pachyphthalmus</i>, etc.</p>
+</div>
+
+<p>pp. Fifth ventral abdominal sclerite of the
+male cleft to beyond the middle; ventral
+sclerites usually visible, shield-like.
+<i>Rhinophora</i>, <i>Phyto</i>, <i>Melanophora</i>.
+<span class="rightalign"><span class="smcap">Rhinophorinæ</span></span></p>
+</div></div>
+
+<p>nn. Second ventral abdominal sclerite as well as
+the others more or less covered, sometimes
+wholly, by the edges of the dorsal sclerite.</p>
+
+<div class="hanging">
+<p>o. The presutural intraalar wanting; ventral
+sclerites two to five nearly or quite covered
+by the edges of the corresponding dorsal
+sclerites; base of the antennæ usually at or
+below the middle of the eye; arista usually
+plumose; legs usually elongate; abdominal
+segments with marginal and often
+discal macrochætæ.        <span class="rightalign"><span class="smcap"><b>Dexiidæ</b></span></span></p>
+
+<p>oo. Presutural intraalar present, if absent, then
+the ventral sclerites broadly exposed
+or the fifth ventral sclerite vestigial;<span class="pagenum"><a name="Page_303" id="Page_303">[Pg 303]</a></span>
+base of the antennæ usually above the
+middle of the eye; arista bare; at least
+two posthumerals and three posterior
+intraalars present. Parasitic on caterpillars,
+etc.        <span class="rightalign"><span class="smcap">Tachinidæ</span></span></p>
+</div></div></div></div></div></div></div></div></div></div></div></div></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_162" id="Fig_162"></a>
+<a href="images/f162-full.png"><img src="images/f162.png" width="450" height="285" alt="162. Hippobosca equina, ×4. After Osborn." title="162. Hippobosca equina, ×4. After Osborn." /></a>
+<span class="caption">162. Hippobosca equina, ×4. After Osborn.</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_163" id="Fig_163"></a>
+<a href="images/f163-full.png"><img src="images/f163.png" width="500" height="707" alt="163. Wings of Diptera. (a) Anopheles; (b) Prosimulium; (c) Johannseniella; (d) Phlebotomus
+(After Doerr and Russ); (e) Tersesthes (after Townsend); (f) Tabanus;
+(g) Symphoromyia; (h) Aphiochæta; (i) Eristalis; (j) Gastrophilus;
+(k) Fannia; (l) Musca." title="163. Wings of Diptera. (a) Anopheles; (b) Prosimulium; (c) Johannseniella; (d) Phlebotomus
+(After Doerr and Russ); (e) Tersesthes (after Townsend); (f) Tabanus;
+(g) Symphoromyia; (h) Aphiochæta; (i) Eristalis; (j) Gastrophilus;
+(k) Fannia; (l) Musca." /></a>
+<span class="caption">163. Wings of Diptera. (<i>a</i>)&nbsp;Anopheles; (<i>b</i>)&nbsp;Prosimulium; (<i>c</i>)&nbsp;Johannseniella; (<i>d</i>)&nbsp;Phlebotomus
+(After Doerr and Russ); (<i>e</i>)&nbsp;Tersesthes (after Townsend); (<i>f</i>)&nbsp;Tabanus;
+(<i>g</i>)&nbsp;Symphoromyia; (<i>h</i>)&nbsp;Aphiochæta; (<i>i</i>)&nbsp;Eristalis; (<i>j</i>)&nbsp;Gastrophilus;
+(<i>k</i>)&nbsp;Fannia; (<i>l</i>)&nbsp;Musca.</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_164" id="Fig_164"></a>
+<a href="images/f164-full.png"><img src="images/f164.png" width="500" height="427" alt="164. Glossina palpalis. (×4.) After Austen." title="164. Glossina palpalis. (×4.) After Austen." /></a>
+<span class="caption">164. Glossina palpalis. (×4.) After Austen.</span>
+</div>
+
+
+<h3>SYNOPSIS OF THE PRINCIPAL GENERA OF THE MUSCIDÆ OF THE WORLD</h3>
+
+<div class="hanging">
+<p>a. Proboscis long, directed forward, adapted for piercing, or oral margin much
+produced, snout-like.</p>
+
+<div class="hanging">
+<p>b. Oral margin produced snout-like; vibrissa placed high above the oral
+margin; antennal arista either pectinate or more or less plumose.</p>
+
+<div class="hanging">
+<p>c. Antennal arista short or long-plumose; neither sex with distinct
+orbital bristles.</p>
+
+<div class="hanging">
+<p>d. No facial carina between the antennæ.        <span class="rightalign"><span class="smcap">Rhynchomyiinæ</span></span></p>
+
+<div class="hanging">
+<p>e. Arista short-plumose. <i>R.&nbsp;speciosa.</i> Europe.        <span class="rightalign"><i>Rhynchomyia</i> R.&nbsp;D.</span></p>
+
+<p>ee. Arista long-plumose. <i>I.&nbsp;phasina</i>. Europe and Egypt. <span class="rightalign"><i>Idiopsis.</i> B.&nbsp;B.</span></p>
+</div>
+
+<p>dd. With flattened carina, the bases of the antennæ separated; no abdominal
+macrochætæ.        <span class="rightalign"><span class="smcap">Cosmininæ</span></span></p>
+
+<div class="hanging">
+<p><i>C. fuscipennis</i>. South Africa.        <span class="rightalign"><i>Cosmina</i></span></p>
+</div></div>
+
+<p>cc. Antennal arista pectinate; bases of the antennæ separated by a flattened
+carina.        <span class="rightalign"><span class="smcap">Rhiniinæ</span> R.&nbsp;D.</span></p>
+
+<div class="hanging">
+<p>d. Cell R<sub>5</sub> open, or closed at the margin.</p>
+
+<div class="hanging">
+<p>e. Third segment of the antenna twice as long as the second; claws of
+both sexes short; cell R<sub>5</sub> open. <i>I.&nbsp;lunata.</i> Eastern Hemisphere.
+<span class="rightalign"><i>Idia</i> Meigen</span></p>
+
+<p>ee. Third segment of the antenna three times as long as the second;
+cell R<sub>5</sub> open or closed; claws of the male long and slender, of the
+female shorter than the last tarsal joint. <i>I.&nbsp;mandarina</i>, China.
+<span class="rightalign"><i>Idiella</i> B.&nbsp;B.</span></p>
+</div>
+
+<p>dd. Cell R<sub>5</sub> petiolate.        <span class="rightalign"><i>Rhinia</i>; and <i>Beccarimyia</i> Rdi.</span></p>
+</div></div>
+
+<p>bb. Proboscis long, directed forward, adapted for piercing.        <span class="rightalign"><span class="smcap"><b>Stomoxinæ</b></span></span></p>
+
+<div class="hanging">
+<p>c. Arista flat, pectinate above with plumose rays; sternopleurals 1:2;
+bases of the veins R<sub>1</sub> and R<sub>4+5</sub> without setæ; base of the media bowed
+down; apical cell opens before the apex of the wing. African species
+<span class="rightalign"><b>Glossina</b> Wied.</span></p>
+
+<div class="hanging">
+<p>d. Species measuring over twelve mm. in length. <i>G. longipennis</i> and <b>fusca</b>.</p>
+
+<p>dd. Species less than twelve mm. in length.</p>
+
+<div class="hanging">
+<p>e. All segments of the hind tarsi black.</p>
+
+<div class="hanging">
+<p>f. The fourth and fifth segments of the fore tarsi black; antennæ
+black (<a href="#Fig_164">fig.&nbsp;164</a>).         <span class="rightalign"><b>G. palpalis</b> R.&nbsp;D.</span></p>
+
+<p>ff. Otherwise marked.        <span class="rightalign"><i>G.&nbsp;bocagei</i>, <i>tachinoides</i>, <i>pallicera</i>.</span></p>
+</div>
+
+<p>ee. First three segments of the hind tarsi are yellow, the fourth and
+fifth segments are black.</p>
+
+<div class="hanging">
+<p>f. Fourth and fifth segments of the first and second pair of tarsi are
+black.</p>
+
+<div class="hanging">
+<p>g. The yellow bands of the abdominal segments occupy a third of
+the segment (<a href="#Fig_165">fig.&nbsp;165</a>).        <span class="rightalign"><b>G. morsitans</b> Westw.</span></p>
+
+<p>gg. The yellow band on each segment of the abdomen occupies a
+sixth of the segment.        <span class="rightalign"><b>G. longipalpis</b> Wied.</span><span class="pagenum"><a name="Page_304" id="Page_304">[Pg 304]</a></span></p>
+</div>
+
+<p>ff. Tarsi of the first and second pairs of legs wholly yellow.
+<span class="rightalign"><i>G. pallidipes</i> Austen</span></p>
+</div></div></div>
+
+<p>cc. Rays of the arista not plumose; only one or two sternopleurals; base of
+the media not strongly bowed down; apical cell opens at or very near
+the apex of the wing.</p>
+
+<div class="hanging">
+<p>d. Vein R<sub>4+5</sub> without setæ at the base; palpi about as long as the proboscis.</p>
+
+<div class="hanging">
+<p>e. Arista pectinate (i.&nbsp;e.&nbsp;rays on one side only), the rays often undulate;
+two yellow sternopleurals often difficult to detect; vein M<sub>1+2</sub>
+only slightly bent, the apical cell hence wide open. The horn fly,
+<b>H. irritans</b> (=&nbsp;<i>Lyperosia serrata</i>) and related species. Widely distributed
+(figs. <a href="#Fig_167">167</a>,&nbsp;<a href="#Fig_168">168</a>).        <span class="rightalign"><b>Hæmatobia</b> R.&nbsp;D. not B.&nbsp;B.</span></p>
+
+<p>ee. Arista also with rays below; vein M<sub>1+2</sub> more strongly bent, the
+apical cell hence less widely open.</p>
+
+<div class="hanging">
+<p>f. Palpi strongly spatulate at the tips, lower rays of the arista about
+six in number, <b>B.&nbsp;sanguinolentus</b>. South Asia.
+<span class="rightalign"><b>Bdellolarynx</b> Austen</span></p>
+
+<p>ff. Palpi feebly spatulate; apical cell of the wing narrowly open
+slightly before the tip; sternopleurals black, anterior bristle
+sometimes absent. <b>H.&nbsp;atripalpis</b>. Europe.
+<span class="rightalign"><b>Hæmatobosca</b> Bezzi</span></p>
+</div></div>
+
+<p>dd. Vein R<sub>4+5</sub> with setæ at the base.<a name="FNanchor_L_12" id="FNanchor_L_12"></a><a href="#Footnote_L_12" class="fnanchor">[L]</a><span class="pagenum"><a name="Page_305" id="Page_305">[Pg 305]</a></span></p>
+
+<div class="hanging">
+<p>e. Veins R<sub>1</sub> and R<sub>4+5</sub> with setæ at the base; two equally prominent
+sternopleural macrochætæ; arista with rays both above and below;
+palpi as long as the proboscis; apical cell of the wing wide
+open. <b>L.&nbsp;tibialis.</b> (<i>Hæmatobia</i> B.&nbsp;B. not R.&nbsp;D.).
+<span class="rightalign"><b>Lyperosiops</b> Town.</span></p>
+
+<p>ee. Only vein R<sub>4+5</sub> with basal setæ; anterior sternopleural macrochæta
+wanting; arista pectinate.</p>
+
+<div class="hanging">
+<p>f. Palpi as long as the proboscis, the latter stout, with fleshy terminal
+labellæ; apical cell narrowly open; sternopleural macrochætæ
+black. <b>S.&nbsp;maculosa</b> from Africa and related species
+from Asia.         <span class="rightalign"><b>Stygeromyia</b> Austen</span></p>
+
+<p>ff. Palpi much shorter than the proboscis, the latter pointed at the
+apex, without fleshy labellæ; apical cell of the wing wide open.
+<b>S.&nbsp;calcitrans</b>, the stable fly and related species. Widely distributed
+in both hemispheres (<a href="#Fig_110">fig.&nbsp;110</a>).        <span class="rightalign"><b>Stomoxys</b> Geof.</span></p>
+</div></div></div></div></div>
+
+<p>aa. Proboscis neither slender nor elongate, the labellæ fleshy and not adapted for
+piercing.</p>
+
+<div class="hanging">
+<p>b. Hypopleuræ without a vertical row of macrochætæ.         <span class="rightalign"><span class="smcap"><b>Muscinæ</b></span></span></p>
+
+<div class="hanging">
+<p>c. Arista bare; distal portion of <span title="for R_{4+5} read M_{1+2}"><a name="AC_18a" id="AC_18a"></a>R<sub>4+5</sub></span> broadly curved at the end; hypopleuræ
+with a sparse cluster of fine hairs. <i>S.&nbsp;braziliana</i>, Southern
+States and southward.         <span class="rightalign"><i>Synthesiomyia</i> B.&nbsp;B.</span></p>
+
+<p>cc. Arista pectinate or plumose.</p>
+
+<div class="hanging">
+<p>d. Arista pectinate. <i>H.&nbsp;vittigera</i>, with the posterior half of the abdomen
+metallic blue. Mexico.         <span class="rightalign"><i>Hemichlora</i> V.&nbsp;d.&nbsp;W.</span></p>
+
+<p>dd. Arista plumose.</p>
+
+<div class="hanging">
+<p>e. Middle tibia with one or more prominent setæ on the inner (flexor)
+surface beyond the middle, or inner surface very hairy.</p>
+
+<div class="hanging">
+<p>f. R<sub>1</sub> ends distad of the m-cu crossvein; <span title="for R_{4+5} read M_{1+2}"><a name="AC_18b" id="AC_18b"></a>R<sub>4+5</sub></span> with a broad curve
+near its apical end. (=&nbsp;<i>Neomesembrina</i> Schnabl. =&nbsp;<i>Metamesembrina</i> Town).
+<i>M.&nbsp;meridiana.</i> Europe.         <span class="rightalign"><i>Mesembrina</i> Meigen</span></p>
+
+<p>ff. R<sub>1</sub> ends proximad of the m-cu crossvein.</p>
+
+<div class="hanging">
+<p>g. Eyes pilose, sometimes sparsely in the female.</p>
+
+<div class="hanging">
+<p>h. Female with two or three stout orbital setæ; the hind metatarsus
+of the male thickened below at the base and penicillate.
+<i>D.&nbsp;pratorum.</i> Europe. <span class="rightalign"><i>Dasyphora</i> R.&nbsp;D.<a name="FNanchor_M_13" id="FNanchor_M_13"></a><a href="#Footnote_M_13" class="fnanchor">[M]</a></span></p>
+
+<p>hh. Neither sex with orbital setæ.</p>
+
+<div class="hanging">
+<p>i. Abdomen without macrochætæ; arista plumose. <i>C.&nbsp;asiatica.</i>
+Eastern Hemisphere.         <span class="rightalign"><i>Cryptolucilia</i> B.&nbsp;B.</span></p>
+
+<p>ii. Abdomen with strong macrochætæ; arista very short-plumose,
+nearly bare. <i>B.&nbsp;tachinina.</i> Brazil.        <span class="rightalign"><i>Reinwardtia</i> B.&nbsp;B.</span></p>
+</div></div>
+
+<p>gg. Eyes bare.</p>
+
+<div class="hanging">
+<p>h. Body densely pilose; thoracic macrochætæ  wanting; middle
+tibiæ much elongate and bent; last section of <span title="for R_{4+5} read M_{1+2}"><a name="AC_18c" id="AC_18c"></a>R<sub>4+5</sub></span> with a
+gentle curve. H.&nbsp;(<i>Mesembrina</i>) <i>mystacea, et&nbsp;al.</i>, Europe
+and <i>H.&nbsp;solitaria</i>, N. America.         <span class="rightalign"><i>Hypodermodes</i> Town.</span></p>
+
+<p>hh. Body not densely pilose.<span class="pagenum"><a name="Page_306" id="Page_306">[Pg 306]</a></span></p>
+
+<div class="hanging">
+<p>i. Dorsocentrals six; last section of <span title="for R_{4+5} read M_{1+2}"><a name="AC_18d" id="AC_18d"></a>R<sub>4+5</sub></span> with a gentle curve.</p>
+
+<div class="hanging">
+<p>j. Inner dorsocentrals ("acrostichals") wanting; sternopleurals
+arranged 1:3. <i>P.&nbsp;cyanicolor</i>, <i>cadaverina</i>, etc.
+Europe and America.          <span class="rightalign"><i>Pyrellia</i> R. D.</span></p>
+
+<p>jj. Inner dorsocentrals ("acrostichals") present; sternopleurals
+arranged 1:2. E.&nbsp;<i>latreillii.</i> North America.
+<span class="rightalign"><i>Eumesembrina</i> Town.</span></p>
+</div>
+
+<p>ii. Dorsocentrals five; inner dorsocentrals present; last
+section of <span title="for R_{4+5} read M_{1+2}"><a name="AC_18e" id="AC_18e"></a>R<sub>4+5</sub></span> with a rounded angle; sternopleurals
+arranged 1:2. <i>P.&nbsp;cornicina</i> Europe and America.
+(<i>Pseudopyrellia</i> Girsch.)          <span class="rightalign"><i>Orthellia</i> R.&nbsp;D.</span></p>
+</div></div></div></div>
+
+<p>ee. Middle tibia without a prominent bristle on the inner surface beyond
+the middle.</p>
+
+<div class="hanging">
+<p>f. Squamula thoracalis broadened mesad and caudad as far as the
+scutellum.</p>
+
+<div class="hanging">
+<p>g. Sternopleural macrochætæ arranged in an equilateral triangle;
+front of both sexes broad; genæ bare; dorsocentrals six,
+small; wing not rilled. (To <span class="smcap">Coenosinæ</span>).         <span class="rightalign"><i>Atherigona</i> Rdi.</span></p>
+
+<p>gg. Sternopleural macrochætæ when three are present, arranged
+in a right triangle.</p>
+
+<div class="hanging">
+<p>h. Last section of <span title="for R_{4+5} read M_{1+2}"><a name="AC_18f" id="AC_18f"></a>R<sub>4+5</sub></span> with a more or less rounded angle
+(<a href="#Fig_163">fig.&nbsp;163l</a>).</p>
+
+<div class="hanging">
+<p>i. Eyes of the male pilose or pubescent, of the female nearly
+bare; m-cu crossvein usually at or proximad of the mid-distance
+between the r-m crossvein and the bend of
+<span title="for R_{4+5} read M_{1+2}"><a name="AC_18g" id="AC_18g"></a>R<sub>4+5</sub></span>. P. (=&nbsp;<i>Placomyia</i> R.&nbsp;D.) <i>vitripennis</i>.
+<span class="rightalign"><i>Plaxemyia</i> R.&nbsp;D.</span></p>
+
+<p>ii. Eyes bare; the m-cu crossvein always nearer to the bend of
+<span title="for R_{4+5} read M_{1+2}"><a name="AC_18h" id="AC_18h"></a>R<sub>4+5</sub></span> than to the r-m crossvein.</p>
+
+<div class="hanging">
+<p>j. Apex of the proboscis when extended reveals a circlet of
+stout chitinous teeth. <b>P.&nbsp;insignis</b> Austen, of India,
+bites both man and animals. (=&nbsp;<i>Pristirhynchomyia</i>)
+<span class="rightalign"><b>Philæmatomyia</b> Austen</span><span class="pagenum"><a name="Page_307" id="Page_307">[Pg 307]</a></span></p>
+
+<p>jj. Apex of the proboscis without black teeth.</p>
+
+<div class="hanging">
+<p>k. Eyes of male separated by a distance equal to a fourth
+the width of the head. House or typhoid fly.
+<b>M.&nbsp;domestica</b> L. Widely distributed.        <span class="rightalign"><b>Musca</b> L.</span></p>
+
+<p>kk. Eyes of the male contiguous. <b>E.&nbsp;corvina.</b> Europe.
+<span class="rightalign"><b>Eumusca</b> Town</span></p>
+</div></div></div>
+
+<p>hh. Last section of <span title="for R_{4+5} read M_{1+2}"><a name="AC_18i" id="AC_18i"></a>R<sub>4+5</sub></span> with a gentle curve (<a href="#Fig_102">fig.&nbsp;102</a>).</p>
+
+<div class="hanging">
+<p>i. Eyes pilose.</p>
+
+<div class="hanging">
+<p>j. Claws in the male somewhat elongated; no orbitals in
+either sex; antennæ separated at the base by a flat
+carina; abdomen marked with red or yellow. <i>G.&nbsp;maculata.</i>
+Europe and America.        <span class="rightalign"><i>Graphomyia</i> R.&nbsp;D.</span></p>
+
+<p>jj. Claws short and equal in the two sexes; two or three
+stout orbital macrochætæ in the female; R<sub>1</sub> scarcely
+produced beyond the r-m crossvein; eyes contiguous
+in the male. <i>P.&nbsp;obsoleta.</i> Brazil.         <span class="rightalign"><i>Phasiophana</i> Br.</span></p>
+</div>
+
+<p>ii. Eyes bare; fronto-orbital macrochætæ in a double row,
+antennæ contiguous at the base.</p>
+
+<div class="hanging">
+<p>j. One or more pairs of well developed anterior inner dorsocentral
+(acrostichal) macrochætæ; seta on extensor
+surface of hind tibia. <b>M.&nbsp;assimilis</b>, <b>stabulans</b>, etc.
+Europe and America.          <span class="rightalign"><b>Muscina</b> R.&nbsp;D.</span></p>
+
+<p>jj. Anterior inner dorsocentrals and the setæ; on the extensor
+surface of the hind tibia wanting. <i>M.&nbsp;micans</i>,
+etc. Europe and North America.        <span class="rightalign"><i>Morellia</i> R.&nbsp;D.</span></p>
+</div></div></div></div>
+
+<p>ff. Squamula thoracalis not broadened mesad and caudad, not
+reaching the margin of the scutellum; macrochætæ on extensor
+surface of the hind tibia wanting.</p>
+
+<div class="hanging">
+<p>g. Eyes pubescent.  <i>M.&nbsp;meditabunda.</i> Europe and America.
+<span class="rightalign"><i>Myiospila</i> Rdi.</span></p>
+
+<p>gg. Eyes bare; R<sub>1</sub> ends before the middle of the wing. A number
+of species from the tropics of both hemispheres.
+<span class="rightalign"><i>Clinopera</i> V.&nbsp;d.&nbsp;W.</span></p>
+</div></div></div></div></div>
+
+<p>bb. Hypopleuræ with a vertical row of macrochætæ.</p>
+
+<div class="hanging">
+<p>c. Eyes pubescent.</p>
+
+<div class="hanging">
+<p>d. R<sub>1</sub> ends about opposite the r-m crossvein; basal section of R<sub>4+5</sub> bristly
+nearly to the crossvein; <i>S.&nbsp;enigmatica</i>. Africa.         <span class="rightalign"><i>Somalia</i> Hough</span></p>
+
+<p>dd. R<sub>1</sub> ends distad of the r-m crossvein.</p>
+
+<div class="hanging">
+<p>e. Eastern hemisphere. Australasia. <i>N.&nbsp;ochracea</i>, <i>dasypthalma</i>.
+<span class="rightalign"><i>Neocalliphora</i> Br.</span></p>
+
+<p>ee. Western Hemisphere. <i>T.&nbsp;muscinum.</i> Mexico. <span class="rightalign"><i>Tyreomma</i> V.&nbsp;d.&nbsp;W.</span></p>
+</div></div>
+
+<p>cc. Eyes bare.</p>
+
+<div class="hanging">
+<p>d. The vibrissal angle situated at a noticeable distance above the level of
+the margin of the mouth.</p>
+
+<div class="hanging">
+<p>e. Sternopleural macrochætæ arranged in the order 1:1.</p>
+
+<div class="hanging">
+<p>f. Genæ with microchætæ.</p>
+
+<div class="hanging">
+<p>g. Body grayish, with depressed yellow woolly hair among the
+macrochætæ; wings folded longitudinally over the body when<span class="pagenum"><a name="Page_308" id="Page_308">[Pg 308]</a></span>
+at rest. Cluster flies. <i>P.&nbsp;rudis</i> and related species, widely
+distributed.          <span class="rightalign"><i>Pollenia</i> R.&nbsp;D.<a name="FNanchor_N_14" id="FNanchor_N_14"></a><a href="#Footnote_N_14" class="fnanchor">[N]</a></span></p>
+
+<p>gg. Body metallic blue or green. Eastern Hemisphere.</p>
+
+<div class="hanging">
+<p>h. Vibrissal angle placed very high above the oral margin; a
+carina between the antennæ; outer posthumeral wanting;
+anterior intraalar present. <i>T.&nbsp;viridaurea.</i> Java.
+<span class="rightalign"><i>Thelychæta</i> Br.</span></p>
+
+<p>hh. Vibrissal angle moderately high above the oral margin;
+carina small or wanting; no post humeral macrochæta;
+lower squamæ hairy above. (=&nbsp;<i>Paracompsomyia</i>
+Hough) (<a href="#Fig_166">fig.&nbsp;166</a>).          <span class="rightalign"><i>Pycnosoma</i> Br.</span></p>
+</div></div>
+
+<p>ff. Genæ bare. <i>S.&nbsp;terminata</i>. Eastern Hemisphere.
+<span class="rightalign"><i>Strongyloneura</i> Bigot</span></p>
+</div>
+
+<p>ee. Sternopleurals arranged 2:1.</p>
+
+<div class="hanging">
+<p>f. Body metallic green or blue, with gray stripes; genæ hairy to the
+lower margin; post humerals often wanting; lower squamæ bare
+above. (=&nbsp;<i>Compsomyia</i> Rdi.).          <span class="rightalign"><b>Chrysomyia</b> R.&nbsp;D.</span></p>
+
+<div class="hanging">
+<p>g. With one or two orbitals; height of bucca less than half the
+height of the eye. South and east U.&nbsp;S. (<a href="#Fig_107">fig.&nbsp;107</a>).
+<span class="rightalign"><b>C.&nbsp;marcellaria</b></span></p>
+
+<p>gg. No orbitals; height of bucca about a third less than height of
+eye. West U.&nbsp;S.          <span class="rightalign"><i>C.&nbsp;wheeleri</i> Hough</span><span class="pagenum"><a name="Page_309" id="Page_309">[Pg 309]</a></span></p>
+</div>
+
+<p>ff. Body black or sordidly metallic greenish gray, usually yellow pollinose
+or variegate; genæ at most hairy above. <i>N.&nbsp;stygia.</i>
+Eastern Hemisphere.          <span class="rightalign"><i>Neopollenia</i> Br.</span></p>
+</div></div>
+
+<p>dd. Vibrissal angle situated nearly on a level of the oral margin.</p>
+
+<div class="hanging">
+<p>e. Species wholly blackish, bluish, or greenish metallic in color.</p>
+
+<div class="hanging">
+<p>f. First section of <span title="for R_{4+5} read M_{1+2}"><a name="AC_18j" id="AC_18j"></a>R<sub>4+5</sub></span> with at most three or four small bristles at
+the immediate base.</p>
+
+<div class="hanging">
+<p>g. The bend of <span title="for R_{4+5} read M_{1+2}"><a name="AC_18k" id="AC_18k"></a>R<sub>4+5</sub></span> a gentle curve; costal spine present; cell R<sub>5</sub>
+closed, ending before the apex of the wing. <i>S.&nbsp;cuprina.</i>
+Java.          <span class="rightalign"><i>Synamphoneura</i> Bigot</span></p>
+
+<p>gg. Bend of R<sub>4+5</sub> angular; or the insect differs in other characters;
+dorsal surface of the squamula thoracalis hairy (except in
+<i>Melinda</i>); arista plumose only on the basal two-thirds
+(except usually in <i>Calliphora</i> and <i>Eucalliphora</i>).</p>
+
+<div class="hanging">
+<p>h. Arista plumose only on the basal two-thirds.</p>
+
+<div class="hanging">
+<p>i. Base of the antennæ ventrad of the middle of the eye; eyes
+of the male nearly contiguous; genæ hairy; second
+abdominal segment with median marginal macrochætæ;
+two, rarely three, postsutural intraalar macrochætæ.</p>
+
+<div class="hanging">
+<p>j. Squamula thoracalis dorsally with long black hairs; male
+hypopygium two-segmented, large, projecting; claws
+and pulvilli of the male elongate; three strong sternopleural
+macrochætæ; genæ at least half the width of the
+eye; buccæ (cheeks) half the height of the eyes; oviviparous.
+<i>O.&nbsp;sepulcralis.</i> Europe.          <span class="rightalign"><i>Onesia</i> R.&nbsp;D.</span></p>
+
+<p>jj. Dorsal surface of the squamula thoracalis bare; male
+hypopygium small, scarcely projecting below; claws
+and pulvilli not elongate; two stout sternopleural
+macrochætæ, sometimes with a delicate one below the
+anterior; genæ nearly linear in the male; buccæ about
+a third of the eye height; oviparous. <i>M.&nbsp;cærulea.</i>
+Europe.          <span class="rightalign"><i>Melinda</i>. R.&nbsp;D.</span><span class="pagenum"><a name="Page_311" id="Page_311">[Pg 311]</a></span></p>
+</div>
+
+<p>ii. Base of the antennæ dorsad of the middle of the eye; eyes
+of both sexes distinctly separated; dorsal surface of
+the squamula thoracalis with black hairs; two postsutural
+intraalar macrochætæ.</p>
+
+<div class="hanging">
+<p>j. Hypopygium of the male large, with a pair of slightly
+curved forceps whose ends are concealed in a longitudinal
+slit in the fifth ventral sclerite; third posterior
+inner dorso-central (acrostichal) macrochætæ absent;
+anterior intraalar rarely present; abdomen usually not
+pollinose; the second segment without median marginal
+macrochætæ; face yellow. <i>C.&nbsp;mortuorum</i>, <i>cadaverina</i>,
+and related species. Both hemispheres.
+<span class="rightalign"><i>Cynomyia</i> R.&nbsp;D.<a name="FNanchor_O_15" id="FNanchor_O_15"></a><a href="#Footnote_O_15" class="fnanchor">[O]</a></span></p>
+
+<p>jj. Three pairs of posterior inner dorsocentrals (acrostichals)
+present; second abdominal segment with a row of
+marginal macrochætæ; genæ hairy, at least above.</p>
+
+<div class="hanging">
+<p>k. Hypopygium of the male with a projecting style.
+<i>S.&nbsp;stylifera</i>. Europe.        <span class="rightalign"><i>Steringomyia</i> Pok.</span><span class="pagenum"><a name="Page_312" id="Page_312">[Pg 312]</a></span></p>
+
+<p>kk. Hypopygium of the male without style. <i>A.&nbsp;stelviana</i>
+B.&nbsp;B.          <span class="rightalign"><i>Acrophaga</i> B.&nbsp;B.</span></p>
+</div></div></div>
+
+<p>hh. Arista usually plumose nearly to the tip; posterior dorsocentrals
+and inner dorsocentrals (acrostichals) well
+developed; dorsal surface of the squamula thoracalis
+hairy; abdomen metallic and usually pollinose; genæ
+hairy.</p>
+
+<div class="hanging">
+<p>i. With one pair of ocellar macrochætæ. <b>C.&nbsp;vomitoria</b>,
+<b>erythrocephala</b>, <b>viridescens</b>, and related species. Both
+hemispheres.          <span class="rightalign"><b>Calliphora</b> R.&nbsp;D.</span></p>
+
+<p>ii. With two strong pairs of ocellar macrochætæ. <i>E.&nbsp;latifrons.</i>
+Pacific slope of the U.&nbsp;S.          <span class="rightalign"><i>Eucalliphora</i> Town.</span></p>
+</div></div></div>
+
+<p>ff. First section of R<sub>4+5</sub> bristly near or quite half way to the small
+crossvein; dorsal surface of the squamula thoracalis is bare;
+the hypopygium of the male is inconspicuous.</p>
+
+<div class="hanging">
+<p>g. Genæ bare; posterior inner and outer dorsocentrals distinct
+and well developed. <i>L.&nbsp;cæsar</i>, <i>sericata</i>, <i>sylvarum</i>, and
+related species. Widely distributed in both hemispheres
+(<a href="#Fig_103">fig.&nbsp;103</a>).          <span class="rightalign"><b>Lucilia</b> R.&nbsp;D.</span></p>
+
+<p>gg. Genæ with microchætæ, at least down to the level of the base
+of the arista.</p>
+
+<div class="hanging">
+<p>h. Mesonotum flattened behind the transverse suture.</p>
+
+<div class="hanging">
+<p>i. Posterior dorsocentrals inconstant and unequally developed;
+one pair of posterior inner dorsocentrals. <i>P.&nbsp;terrænovæ.</i>
+North America.          <span class="rightalign"><i>Protophormia</i> Town.</span></p>
+
+<p>ii. Posterior dorsocentrals well developed, the inner dorsocentrals
+(acrostichals) unequally developed. <i>P.&nbsp;azurea</i>,
+<i>chrysorrh&oelig;a</i>, etc. Europe and America.
+<span class="rightalign"><i>Protocalliphora</i> Hough</span></p>
+</div>
+
+<p>hh. Mesonotum not flattened behind the transverse suture;
+posterior inner and outer dorsocentrals inconstant
+and unequally developed. <i>P.&nbsp;regina.</i> Europe and
+America.         <span class="rightalign"><i>Phormia</i> R.&nbsp;D.</span></p>
+</div></div></div>
+
+<p>ee. Species more or less rufous or yellow in color.</p>
+
+<div class="hanging">
+<p>f. Anterior dorsocentrals wanting; first section of the R<sub>4+5</sub> at most
+only bristly at the base, bend <span title="for &quot;near apex&quot; read &quot;of M_{1+2}&quot;"><a name="AC_20" id="AC_20"></a>near apex</span> rectangular, R<sub>1</sub> ends over
+the crossvein; fronto-orbital macrochæta absent; eyes of the
+male contiguous. <i>C.&nbsp;semiviridis.</i> Mexico.         <span class="rightalign"><i>Chloroprocta</i> V.&nbsp;d.&nbsp;W.</span></p>
+
+<p>ff. With another combination of characters.</p>
+
+<div class="hanging">
+<p>g. Body robust, of large size, abdomen elongate, not round; genæ
+with several ranges of microchætæ; vibrissal ridges strongly
+convergent; abdomen with well developed macrochætæ;
+costal spine usually absent; eyes of the male widely separated.</p>
+
+<div class="hanging">
+<p>h. Peristome broad, pteropleural macrochætæ distinct; one or
+two sternopleurals; in the female a single orbital macrochæta;
+last abdominal segment without discal macrochætæ;
+hypopygial processes of the male with a long
+stylet; second abdominal segment of the female sometimes<span class="pagenum"><a name="Page_314" id="Page_314">[Pg 314]</a></span>
+much elongate. <b>A.&nbsp;luteola</b> (<a href="#Fig_86">fig.&nbsp;86</a>). Africa. The sub-genus
+<i>Ch&oelig;romyia</i> Roub. is included here. <span class="rightalign"><b>Auchmeromyia</b> B.&nbsp;B.</span></p>
+
+<p>hh. Peristome narrow; no pteropleurals, two sternopleurals;
+two orbitals in the female; second segment not elongate;
+the fourth with two well developed discal macrochætæ.
+<b>B.&nbsp;depressa.</b> Africa.        <span class="rightalign"><b>Bengalia</b> R.&nbsp;D</span></p>
+</div>
+
+<p>gg. With another combination of characters.</p>
+
+<div class="hanging">
+<p>h. Costal spine present; body in part black; antennæ noticeably
+shorter than the epistome, inserted above the middle
+of the eye and separated from each other by a carina;
+abdominal segments with marginal macrochætæ; sternopleurals
+2:1 or 1:1.        <span class="rightalign"><i>Paratricyclea</i> Villen.</span></p>
+
+<p>hh. Costal spine not distinct, or if present, insect otherwise
+different.</p>
+
+<div class="hanging">
+<p>i. Genæ with several ranges of microchætæ; vibrissal ridges
+strongly converging; peristome broad; arista moderately
+plumose; sternopleurals usually 1:1; color entirely
+testaceous. <b>C.&nbsp;anthropophaga</b> (<a href="#Fig_87">fig.&nbsp;87</a>) and <b>grunbergi</b>.
+Africa.        <span class="rightalign"><b>Cordylobia</b> Grünb.</span></p>
+
+<p>ii. Genæ bare or with but one range of setæ; vibrissal ridges
+less converging; peristome narrow; arista long plumose.</p>
+
+<div class="hanging">
+<p>j. Genæ with a single row of microchætæ.</p>
+
+<div class="hanging">
+<p>k. Sternopleurals 2:1; color entirely testaceous.
+<span class="rightalign"><i>Ochromyia</i> Macq.<a name="FNanchor_P_16" id="FNanchor_P_16"></a><a href="#Footnote_P_16" class="fnanchor">[P]</a></span></p>
+
+<p>kk. Sternopleurals 1:1. <i>P.&nbsp;varia</i> Hough. Africa.
+<span class="rightalign"><i>Parochromyia</i> Hough</span></p>
+</div>
+
+<p>jj. Genæ bare.</p>
+
+<div class="hanging">
+<p>k. Basal section of R<sub>4+5</sub> bristly only at the immediate
+base, <span title="for &quot;distal section&quot; read &quot;distally M_{1+2}&quot;"><a name="AC_22" id="AC_22"></a>distal section</span> with a broad curve; distal
+portion of the abdomen metallic; sternopleurals
+usually 1:1, rarely 2:1. <i>M.&nbsp;æneiventris</i> Wd. Tropic
+America.        <span class="rightalign"><i>Mesembrinella.</i> G.&nbsp;T.</span></p>
+
+<p>kk. R<sub>4+5</sub> bristly at least nearly half way to the small
+crossvein; sternopleurals 1:1.</p>
+
+<div class="hanging">
+<p>l. Macrochætæ of the abdomen marginal; neither sex
+with orbitals; no carina between the base of the
+antennæ; three pairs of presutural inner dorsocentrals.
+Eastern hemisphere. <i>T.&nbsp;ferruginea.</i>
+<i>Tricyclea V.&nbsp;d.&nbsp;W.</i> (=&nbsp;<i>Zonochroa</i> B.&nbsp;B. according
+to Villeneuve 1914).</p>
+
+<p>ll. Abdomen without macrochætæ; wing usually with
+a marginal streak and gray markings. Brazil
+<span class="rightalign">Hemilucilia B.&nbsp;B.</span></p>
+</div></div></div></div></div></div></div></div></div></div></div></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_165" id="Fig_165"></a>
+<a href="images/f165-full.png"><img src="images/f165.png" width="450" height="365" alt="165. Glossina morsitans. (×4.) After Austen." title="165. Glossina morsitans. (×4.) After Austen." /></a>
+<span class="caption">165. Glossina morsitans. (×4.) After Austen.</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_166" id="Fig_166"></a>
+<a href="images/f166-full.png"><img src="images/f166.png" width="500" height="316" alt="166. Pycnosoma marginale. (×4.) After Graham-Smith." title="166. Pycnosoma marginale. (×4.) After Graham-Smith." /></a>
+<span class="caption">166. Pycnosoma marginale. (×4.) After Graham-Smith.</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_167" id="Fig_167"></a>
+<a href="images/f167-full.png"><img src="images/f167.png" width="500" height="339" alt="167. Horn fly. (a) egg; (b) larva; (c) puparium; (d) adult. (×4). Bureau of Entomology" title="167. Horn fly. (a) egg; (b) larva; (c) puparium; (d) adult. (×4). Bureau of Entomology" /></a>
+<span class="caption">167. Horn fly. (<i>a</i>)&nbsp;egg; (<i>b</i>)&nbsp;larva; (<i>c</i>)&nbsp;puparium; (<i>d</i>)&nbsp;adult. (×4). Bureau of Entomology</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_168" id="Fig_168"></a>
+<a href="images/f168-full.png"><img src="images/f168.png" width="500" height="247" alt="168. Head of horn-fly (Lyperosia irritans); (a) female; (b) male; (c) lateral aspect of female." title="168. Head of horn-fly (Lyperosia irritans); (a) female; (b) male; (c) lateral aspect of female." /></a>
+<span class="caption"><span title="add Bureau of Entomology">168. Head of horn-fly (Lyperosia irritans); (<i>a</i>)&nbsp;female; (<i>b</i>)&nbsp;male; (<i>c</i>)&nbsp;lateral aspect of female.</span></span>
+</div>
+
+<div class="figcenter" style="width: 500px;">
+<a href="images/f169-full.png"><img src="images/f169.png" width="500" height="792" alt="169. Lateral and dorsal aspects of the thorax, and frontal aspect of the head of a muscoidean
+fly, with designations of the parts commonly used in taxonomic work." title="169. Lateral and dorsal aspects of the thorax, and frontal aspect of the head of a muscoidean
+fly, with designations of the parts commonly used in taxonomic work." /></a>
+<span class="caption">169. Lateral and dorsal aspects of the thorax, and frontal aspect of the head of a muscoidean
+fly, with designations of the parts commonly used in taxonomic work.</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_170" id="Fig_170"></a>
+<a href="images/f170-full.png"><img src="images/f170.png" width="500" height="386" alt="170. Sepsis violacea; puparium and adult. (See page 297.) After Howard." title="170. Sepsis violacea; puparium and adult. (See page 297.) After Howard." /></a>
+<span class="caption">170. Sepsis violacea; puparium and adult. (See <a href="#Page_297">page 297</a>.) After Howard.</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_171" id="Fig_171"></a>
+<a href="images/f171-full.png"><img src="images/f171.png" width="500" height="326" alt="171. Stigmata of the larvæ of Muscoidea. Third instar. (a) Cynomyia cadaverina; (b) Phormia regina; (c) Chrysomyia macellaria;
+(d) Musca domestica; (e) Sarcophaga sp.; (f) Oestris ovis; (g) Gastrophilus equi; (h) Sarcophaga sp.; (i) Pegomyia
+vicina; (j) Protocalliphora azurea; (k) Hypoderma lineata; (l) Muscina stabulans. Magnification for f, g, and k, ×25;
+all others, ×50." title="171. Stigmata of the larvæ of Muscoidea. Third instar. (a) Cynomyia cadaverina; (b) Phormia regina; (c) Chrysomyia macellaria;
+(d) Musca domestica; (e) Sarcophaga sp; (f) Oestris ovis; (g) Gastrophilus equi; (h) Sarcophaga sp; (i) Pegomyia
+vicina; (j) Protocalliphora azurea; (k) Hypoderma lineata; (l) Muscina stabulans. Magnification for f, g, and k, ×25;
+all others, ×50." /></a>
+<span class="caption">171. Stigmata of the larvæ of Muscoidea. Third instar. (<i>a</i>)&nbsp;Cynomyia cadaverina; (<i>b</i>)&nbsp;Phormia regina; (<i>c</i>)&nbsp;Chrysomyia macellaria;
+(<i>d</i>)&nbsp;Musca domestica; (<i>e</i>)&nbsp;Sarcophaga sp; (<i>f</i>)&nbsp;Oestris ovis; (<i>g</i>)&nbsp;Gastrophilus equi; (<i>h</i>)&nbsp;Sarcophaga sp; (<i>i</i>)&nbsp;Pegomyia
+vicina; (<i>j</i>)&nbsp;Protocalliphora azurea; (<i>k</i>)&nbsp;Hypoderma lineata; (<i>l</i>)&nbsp;Muscina stabulans. Magnification for f, g, and&nbsp;k, ×25;
+all others, ×50.</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_172" id="Fig_172"></a>
+<a href="images/f172-full.png"><img src="images/f172.png" width="500" height="698" alt="172. Left hand stigmata of the larvæ of muscoidea. Third instar. (a) Lucilia cæsar;
+(b) Calliphora vomitoria; (c) Stomoxys calcitrans; (d) Pseudopyrellia cornicina;
+(e) Pyrellia cadavarina; (f) Lyperosia irritans; (g) Mesembrina mystacea; (h)
+Mesembrina meridiana; (i) Myospila meditabunda; (j) Mydæa umbana; (k)
+Polietes albolineata; (l) Polietes lardaria; (m) Morellia hortorum; (n) Hydrotæa
+dentipes; (o) Hebecnema umbratica; (p) H. vespertina; (q) Limnophora septemnotata;
+(r) Muscina stabulans. (a and b) after MacGregor; (d) after Banks;
+all others after Portchinsky. Magnification varies. The relative distance to the
+median line is indicated in each figure." title="172. Left hand stigmata of the larvæ of muscoidea. Third instar. (a) Lucilia cæsar;
+(b) Calliphora vomitoria; (c) Stomoxys calcitrans; (d) Pseudopyrellia cornicina;
+(e) Pyrellia cadavarina; (f) Lyperosia irritans; (g) Mesembrina mystacea; (h)
+Mesembrina meridiana; (i) Myospila meditabunda; (j) Mydæa umbana; (k)
+Polietes albolineata; (l) Polietes lardaria; (m) Morellia hortorum; (n) Hydrotæa
+dentipes; (o) Hebecnema umbratica; (p) H. vespertina; (q) Limnophora septemnotata;
+(r) Muscina stabulans. (a and b) after MacGregor; (d) after Banks;
+all others after Portchinsky. Magnification varies. The relative distance to the
+median line is indicated in each figure." /></a>
+<span class="caption">172. Left hand stigmata of the larvæ of muscoidea. Third instar. (<i>a</i>)&nbsp;Lucilia cæsar;
+(<i>b</i>)&nbsp;Calliphora vomitoria; (<i>c</i>)&nbsp;Stomoxys calcitrans; (<i>d</i>)&nbsp;<span title="for Pseudopyrellia read Orthellia">Pseudopyrellia</span> cornicina;
+(<i>e</i>)&nbsp;Pyrellia cadavarina; (<i>f</i>)&nbsp;<span title="for Lyperosia read Hæmatobia">Lyperosia</span> irritans; (<i>g</i>)&nbsp;Mesembrina mystacea;
+(<i>h</i>)&nbsp;Mesembrina meridiana; (<i>i</i>)&nbsp;Myospila meditabunda; (<i>j</i>)&nbsp;Mydæa <span title="for Umbana read urbana">umbana</span>;
+(<i>k</i>)&nbsp;Polietes albolineata; (<i>l</i>)&nbsp;Polietes lardaria; (<i>m</i>)&nbsp;Morellia hortorum; (<i>n</i>)&nbsp;Hydrotæa
+dentipes; (<i>o</i>)&nbsp;Hebecnema umbratica; (<i>p</i>)&nbsp;H. vespertina; (<i>q</i>)&nbsp;Limnophora septemnotata;
+(<i>r</i>)&nbsp;Muscina stabulans. (<i>a</i> and <i>b</i>) after MacGregor; (<i>d</i>)&nbsp;after Banks;
+all others after Portchinsky. Magnification varies. The relative distance to the
+median line is indicated in each figure.</span>
+</div><p><span class="pagenum"><a name="Page_316" id="Page_316">[Pg 316]</a></span></p>
+
+
+<h3><a name="SIPHONAPTERA_Fleas" id="SIPHONAPTERA_Fleas"></a>SIPHONAPTERA. Fleas</h3>
+
+<p class="center">Adapted from a table published by Oudemans.</p>
+
+<div class="hanging">
+<p>a. Elongated fleas, with jointed (articulated) head, with combs (ctenidia) on
+head and thorax; with long, oval, free-jointed flagellum of the antenna
+(<a href="#Fig_92">fig.&nbsp;92d</a>).                  <span class="rightalign">Suborder FRACTICIPATA</span></p>
+
+<div class="hanging">
+<p>b. With ctenidia in front of the antennæ and on the genæ (cheeks); maxillæ
+with acute apices; labial palpi five-segmented, symmetrical; eyes poorly
+developed or wanting. On rodents.           <span class="rightalign"><span class="smcap">Hystrichopsyllidæ</span></span></p>
+
+<div class="hanging">
+<p>c. Abdominal segments without ctenidia.</p>
+
+<div class="hanging">
+<p>d. Post-tibial spines in pairs and not in a very close set row; head with
+ctenidia.                         <span class="rightalign"><i>Ctenophthalmus</i> Kol.</span></p>
+
+<p>dd. Post-tibial spines mostly single and in a close set row. <i>Ctenopsyllus</i>
+and <i>Leptopsyllus</i>. The last genus has recently been erected for
+<i>L.&nbsp;musculi</i>, a widely distributed species occurring on rats and mice.</p>
+</div>
+
+<p>cc. Abdominal segments with one or more ctenidia; post-tibial spines in
+numerous, short, close-set transverse rows on posterior border with
+about four spines in each row. <i>H.&nbsp;americana.</i>           <span class="rightalign"><i>Hystrichopsylla</i> Taschenb.</span></p>
+</div>
+
+<p>bb. With only two pairs of subfrontal ctenidia; labial palpi five-segmented,
+symmetrical; eyes vestigial or wanting. On bats. (=&nbsp;<span class="smcap">Ischnopsyllidæ</span>).
+<span class="rightalign"><span class="smcap">Nycteridipsyllidæ</span></span></p>
+
+<div class="hanging">
+<p>With more or less blunt maxilla; all tibiæ with notch; a single antepygidial
+bristle; metepimeron without ctenidium. <i>N.&nbsp;crosbyi</i> from
+Missouri was found on bats. Rothschild suggests that this is probably
+the same as <i>N.&nbsp;insignis</i>.
+<span class="rightalign">(=&nbsp;<i>Ischnopsyllus</i> =&nbsp;<i>Ceratopsyllus</i>), <i>Nycteridiphilus</i></span></p>
+</div></div>
+
+<p>aa. Head not jointed, i.e.&nbsp;the segments coalescent, traces of the segmentation
+still being visible in the presence of the vertex tubercle, the falx (sickle-shaped
+process), and a suture.            <span class="rightalign">Suborder INTEGRICIPITA</span></p>
+
+<div class="hanging">
+<p>b. Flagellum of the antennæ long and oval.</p>
+
+<div class="hanging">
+<p>c. Usually elongate fleas, with a free-segmented flagellum of the antenna;
+thorax not shorter than the head, longer than the first tergite.</p>
+
+<div class="hanging">
+<p>d. Genæ of the head and the pronotum with ctenidia.          <span class="rightalign"><span class="smcap">Neopsyllidæ</span></span></p>
+
+<div class="hanging">
+<p>e. Labial palpi four or five-segmented; symmetrical; hind coxæ with
+patch of spines inside; row of six spatulate spines on each side in
+front of the antennæ. <i>C.&nbsp;ornate</i> found on a California mole.
+<span class="rightalign"><i>Corypsylla</i></span></p>
+
+<p>ee. Labial palpi two-segmented, transparent, membranous. On
+hares.       <span class="rightalign"><i>Spilopsyllus</i> Baker</span></p>
+</div>
+
+<p>dd. No ctenidium on the head.</p>
+
+<div class="hanging">
+<p>e. Pronotum with ctenidium.          <span class="rightalign"><span class="smcap"><b>Dolichopsyllidæ</b></span></span></p>
+
+<div class="hanging">
+<p>f. Labial palpi five-segmented, symmetrical.</p>
+
+<div class="hanging">
+<p>g. Antepygidial bristles one to three; eyes present.</p>
+
+<div class="hanging">
+<p>h. Inner side of hind coxæ distally with a comb of minute teeth;
+falx present. On rodents and carnivores.
+<span class="rightalign"><i>Odontopsyllus</i> Baker</span></p>
+
+<p>hh. Inner side of hind coxæ without comb or teeth. Many
+North American species on rodents.
+<span class="rightalign"><b>Ceratophyllus</b> Curtis</span><span class="pagenum"><a name="Page_317" id="Page_317">[Pg 317]</a></span></p>
+</div>
+
+<p>gg. Antepygidial bristles five on each side; eyes absent; suture
+white. <i>D.&nbsp;stylosus</i> on rodents.          <span class="rightalign"><i>Dolichopsyllus</i> Baker</span></p>
+</div>
+
+<p>ff. Labial palpi four or five-segmented; asymmetrical (membranous
+behind), apex acute. <i>Hoplopsyllus anomalus</i> found on Spermophiles
+in Colorado.  <span class="rightalign"><span class="smcap">Hoplopsyllidæ</span></span></p>
+</div>
+
+<p>ee. Pronotum without ctenidium. <i>Anomiopsyllus californicus</i> and
+<i>nudatus</i> on rodents.           <span class="rightalign"><span class="smcap">Anomiopsyllidæ</span></span></p>
+</div></div>
+
+<p>cc. Very short fleas; flagellum of the antenna with pseudo-segments coalescent;
+thorax much shorter than the head and than the first tergite
+<span class="rightalign"><span class="smcap"><b>Hectopsyllidæ</b></span></span></p>
+
+<div class="hanging">
+<p>Flagellum of the antenna with six coalescent pseudo-segments; maxilla
+blunt. The chigger on man (<a href="#Fig_93">fig.&nbsp;93</a>). <b>D. penetrans.</b>
+<span class="rightalign">(=&nbsp;<b>Rhynchoprion</b> =&nbsp;<b>Sarcopsylla</b>) <b>Dermatophilus</b> Guérin</span></p>
+</div></div>
+
+<p>bb. Flagellum short, round, free portion of the first segment shaped like a
+mandolin.</p>
+
+<div class="hanging">
+<p>c. Thorax not shorter than the head, longer than the first tergite; flagellum
+either with free segments or in part with the segments coalescent.</p>
+
+<div class="hanging">
+<p>d. Head and pronotum with ctenidium; labial palpi asymmetrical.        <span class="rightalign"><span class="smcap"><b>Archæopsyllidæ</b></span></span></p>
+
+<div class="hanging">
+<p>With four subfrontal, four genal, and one angular ctenidia. Widely
+distributed.          <span class="rightalign"><b>Ctenocephalus</b> Kol</span>.</p>
+
+<p>e. Head rounded in front (<a href="#Fig_92">fig.&nbsp;92a</a>). Dog flea.          <span class="rightalign"><b>C. canis</b></span></p>
+
+<p>ee. Head long and flat (<a href="#Fig_92">fig.&nbsp;92b</a>). Cat flea.           <span class="rightalign"><b>C. felis</b></span></p>
+</div>
+
+<p>dd. Neither head nor pronotum with ctenidium. Labial palpi asymmetrical,
+membranous behind.          <span class="rightalign"><span class="smcap"><b>Pulicidæ</b></span></span></p>
+
+<div class="hanging">
+<p>e. Mesosternite narrow, without internal rod-like thickening from the
+insertion of the coxæ upwards. Human flea, etc.          <span class="rightalign"><b>Pulex</b> L.</span></p>
+
+<p>ee. Mesosternite broad with a rod-like internal thickening from the
+insertion of the coxæ upwards (<a href="#Fig_89">fig.&nbsp;89</a>). <b>X. (L&oelig;mopsylla) cheopis</b>,
+plague or rat flea.          <span class="rightalign"><b>Xenopsylla</b></span></p>
+</div></div>
+
+<p>cc. Thorax much shorter than the head and than the first tergite. <b>Echidnophagidæ.</b>
+<b>E.&nbsp;gallinacea</b>, the hen flea also attacks man (<a href="#Fig_96">fig.&nbsp;96</a>).
+<span class="rightalign">(=&nbsp;<b>Argopsylla</b> =&nbsp;<b>Xestopsylla</b>) <b>Echidnophaga</b> Olliff.</span></p>
+</div></div></div>
+
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_E_5" id="Footnote_E_5"></a><a href="#FNanchor_E_5"><span class="label">[E]</span></a> Adapted from Banks, Nuttall, Warburton, Stiles, <i>et&nbsp;al.</i></p></div>
+
+<div class="footnote"><p><a name="Footnote_F_6" id="Footnote_F_6"></a><a href="#FNanchor_F_6"><span class="label">[F]</span></a> Dr. C.&nbsp;W. Stiles considers the species which is responsible for spotted fever distinct from the
+<i>venustus</i> of Banks, separating it as follows:
+</p><p>
+Goblet cells about 75 in the male or 105 in the female. Texas. <i>D.&nbsp;venustus.</i>
+</p><p>
+Goblet cells 157 in the male, or 120 in the female; stigmal plate shaped as shown in the figure
+(<a href="#Fig_150">figs. 150 a, b</a>). Montana, etc. <b>D.&nbsp;andersoni.</b></p></div>
+
+<div class="footnote"><p><a name="Footnote_G_7" id="Footnote_G_7"></a><a href="#FNanchor_G_7"><span class="label">[G]</span></a> Professor C.&nbsp;R. Crosby who has been working upon certain capsids states that he and his
+assistant have been bitten by <b>Lygus pratensis</b>, the tarnished plant bug, by <b>Chlamydatus associatus</b>
+and by <b>Orthotylus flavosparsus</b>, though without serious results.</p></div>
+
+<div class="footnote"><p><a name="Footnote_H_8" id="Footnote_H_8"></a><a href="#FNanchor_H_8"><span class="label">[H]</span></a> Species marked with an&nbsp;* are known to transmit malaria. Species found only in tropical
+North America and not known to carry malaria have been omitted from this table, but all found
+in the United States are included.</p></div>
+
+<div class="footnote"><p><a name="Footnote_I_9" id="Footnote_I_9"></a><a href="#FNanchor_I_9"><span class="label">[I]</span></a> This table to the North American genera of the Tabanidæ is adapted from one given by
+Miss Ricardo.</p></div>
+
+<div class="footnote"><p><a name="Footnote_J_10" id="Footnote_J_10"></a><a href="#FNanchor_J_10"><span class="label">[J]</span></a> The classification of the Muscoidea as set forth by Schiner and other earlier writers has
+long been followed, although it is not satisfactory, being admittedly more or less artificial. Within
+the last two or three decades several schemes have been advanced, that of Brauer and Bergenstamm
+and of Girschner, with the modifications of Schnabl and Dziedzicki having obtained most
+favor in Europe. Townsend, in 1908, proposed a system which differs from Girschner's in some
+respects, but unfortunately it has not yet been published in sufficient detail to permit us to adopt
+it. From considerations of expediency we use here the arrangement given in Aldrich's Catalogue
+of North American Diptera, though we have drawn very freely upon Girschner's most excellent
+paper for taxonomic characters to separate the various groups.</p>
+
+<p>It may sometimes be found that a species does not agree in all the characters with the synopsis;
+in this case it must be placed in the group with which it has the most characters in common.</p></div>
+
+<div class="footnote"><p><a name="Footnote_K_11" id="Footnote_K_11"></a><a href="#FNanchor_K_11"><span class="label">[K]</span></a> There are several genera of flies of the family <i>Cordyluridæ</i>; (i.e.&nbsp;<i>Acalyptratæ</i>) which might be
+placed with the <i>Anthomyiidæ</i> (i.e.&nbsp;<i>Calyptratæ</i>), owing to the relatively large size of their squamæ.
+As there is no single character which will satisfactorily separate all doubtful genera of these two
+groups we must arbitrarily fix the limits. In general those forms on the border line having a
+costal spine, or lower squama larger than the upper, or the lower surface of the scutellum more
+or less pubescent, or the eyes of the male nearly or quite contiguous, or the eyes hairy, or the
+frontal setæ decussate in the female; or any combination of these characters may at once be
+placed with the <i>Anthomyiidæ</i>. Those forms which lack these characteristics and have at least
+six abdominal segments (the first and second segments usually being more or less coalescent)
+are placed with the Acalyptrates. There are other acalyptrates with squamæ of moderate size
+which have either no vibrissæ, or have the subcosta either wholly lacking or coalescent in large
+part with R<sub>1</sub> or have spotted wings; they, therefore will not be confused with the calyptrates.</p></div>
+
+<div class="footnote"><p><a name="Footnote_L_12" id="Footnote_L_12"></a><a href="#FNanchor_L_12"><span class="label">[L]</span></a> <i>Pachymyia</i> Macq. is closely related to <i>Stomoxys</i>. It differs in having the arista rayed both
+above and below. <i>P.&nbsp;vexans</i>, Brazil.</p></div>
+
+<div class="footnote"><p><a name="Footnote_M_13" id="Footnote_M_13"></a><a href="#FNanchor_M_13"><span class="label">[M]</span></a> The genus <i>Eudasyphora</i> Town. has recently been erected to contain <i>D.&nbsp;lasiophthalma</i>.</p></div>
+
+<div class="footnote"><p><a name="Footnote_N_14" id="Footnote_N_14"></a><a href="#FNanchor_N_14"><span class="label">[N]</span></a> <i>Nitellia</i>, usually included in this genus has the apical cell petiolate. <i>Apollenia</i> Bezzi, has
+recently been separated from <i>Pollenia</i> to contain the species <i>P.&nbsp;nudiuscula</i>. Both genera belong
+to the Eastern hemisphere.</p></div>
+
+<div class="footnote"><p><a name="Footnote_O_15" id="Footnote_O_15"></a><a href="#FNanchor_O_15"><span class="label">[O]</span></a> The following three genera are not sufficiently well defined to place in this synopsis. In
+color and structural characters they are closely related to <i>Cynomyia</i> from which they may be
+distinguished as follows. <i>Catapicephala</i> Macq., represented by the species <i>C.&nbsp;splendens</i> from
+Java, has the setæ on the facial ridges rising to the base of the antennæ and has median marginal
+macrochætæ on the abdominal segments two to four: <i>Blepharicnema</i> Macq., represented by
+<i>B.&nbsp;splendens</i> from Venezuela has bare genæ, oral setæ not ascending; tibiæ villose; claws short
+in both sexes; <i>Sarconesia</i> Bigot with the species <i>S.&nbsp;chlorogaster</i> from Chile, setose genæ; legs
+slender, not villose; claws of the male elongate.</p></div>
+
+<div class="footnote"><p><a name="Footnote_P_16" id="Footnote_P_16"></a><a href="#FNanchor_P_16"><span class="label">[P]</span></a> <i>Plinthomyia</i> Rdi. and <i>Hemigymnochæta</i> Corti are related to <i>Ochromyia</i>, though too briefly
+described to place in the key.</p></div></div>
+<p><span class="pagenum"><a name="Page_318" id="Page_318">[Pg 318]</a></span></p>
+
+
+
+
+<h2><a name="APPENDIX" id="APPENDIX"></a>APPENDIX</h2>
+
+
+<h3><a name="HYDROCYANIC_ACID_GAS_AGAINST_HOUSEHOLD_INSECTS" id="HYDROCYANIC_ACID_GAS_AGAINST_HOUSEHOLD_INSECTS"></a>HYDROCYANIC ACID GAS AGAINST HOUSEHOLD INSECTS</h3>
+
+<p>The following directions for fumigating with hydrocyanic acid
+gas are taken from Professor Herrick's circular published by the
+Cornell Reading Course:</p>
+
+<p>Hydrocyanic acid gas has been used successfully against household
+insects and will probably be used more and more in the future.
+It is particularly effective against bed-bugs, and cockroaches, but
+because <i>it is such a deadly poison it must be used very carefully</i>.</p>
+
+<p>The gas is generated from the salt potassium cyanid, by treating
+it with sulfuric acid diluted with water. Potassium cyanid is a
+most poisonous substance and the gas emanating from it is also
+deadly to most, if not all, forms of animal life. The greatest care
+must always be exercised in fumigating houses or rooms in buildings
+that are occupied. Before fumigation a house should be vacated.
+It is not necessary to move furniture or belongings except brass or
+nickel objects, which may be somewhat tarnished, and butter, milk,
+and other larder supplies that are likely to absorb gas. If the nickel
+and brass fixtures or objects are carefully covered with blankets
+they will usually be sufficiently protected.</p>
+
+<p>There may be danger in fumigating one house in a solid row of
+houses if there is a crack in the walls through which the gas may find
+its way. It also follows that the fumigation of one room in a house
+may endanger the occupants of an adjoining room if the walls between
+the two rooms are not perfectly tight. It is necessary to keep
+all these points in mind and to do the work deliberately and thoughtfully.
+The writer has fumigated a large college dormitory of 253
+rooms, once a year for several years, without the slightest accident
+of any kind. In order to fumigate this building about 340 pounds
+of cyanid and the same amount of sulfuric acid were used each time.
+In addition to this, the writer has fumigated single rooms and smaller
+houses with the gas. In one instance the generating jars were too
+small; the liquid boiled over and injured the floors and the rugs.
+Such an accident should be avoided by the use of large jars and by
+placing old rugs or a quantity of newspapers beneath the jars.<span class="pagenum"><a name="Page_319" id="Page_319">[Pg 319]</a></span></p>
+
+
+<h3><a name="The_Proportions_of_Ingredients" id="The_Proportions_of_Ingredients"></a><span class="smcap">The Proportions of Ingredients</span></h3>
+
+<p>Experiments and experience have shown that the potassium
+cyanid should be ninety-eight per cent pure in order to give satisfactory
+results. The purchaser should insist on the cyanid being of
+at least that purity, and it should be procurable at not more than
+forty cents per pound. The crude form of sulfuric acid may be used.
+It is a thickish, brown liquid and should not cost more than four or
+five cents a pound. If a room is made tight, one ounce of cyanid for
+every one hundred cubic feet of space has been shown to be sufficient.
+It is combined with the acid and water in the following proportions:</p>
+
+
+<div class="center">
+<table border="0" cellpadding="4" cellspacing="0" summary="">
+<tr><td align="left">Potassium cyanid</td><td align="left">1 ounce</td></tr>
+<tr><td align="left">Commercial sulfuric acid</td><td align="left">1 fluid ounce</td></tr>
+<tr><td align="left">Water</td><td align="left">3 fluid ounces</td></tr>
+</table></div>
+
+
+<h3><a name="A_Single_Room_As_an_Example" id="A_Single_Room_As_an_Example"></a><span class="smcap">A Single Room As an Example</span></h3>
+
+<p>Suppose a room to be 12 by 15 by 8 feet. It will contain
+12 × 15 × 8, or 1440 cubic feet. For convenience the writer always
+works on the basis of complete hundreds; in this case he would
+work on the basis of 1500 cubic feet, and thus be sure to have enough.
+The foregoing room, then, would require 15 ounces of cyanid, 15
+ounces of sulfuric acid, and 45 ounces of water. The room should
+be made as tight as possible by stopping all the larger openings,
+such as fireplaces and chimney flues, with old rags or blankets.
+Cracks about windows or in other places should be sealed with narrow
+strips of newspaper well soaked in water. Strips of newspaper two
+or three inches wide that have been thoroughly soaked in water may
+be applied quickly and effectively over the cracks around the window
+sash and elsewhere. Such strips will stick closely for several hours
+and may be easily removed at the conclusion of the work.</p>
+
+<p>While the room is being made tight, the ingredients should be
+measured according to the formula already given. The water should
+be measured and <i>poured first</i> into a stone jar for holding at least two
+gallons. The jar should be placed in the middle of the room, with
+an old rug or several newspapers under it in order to protect the floor.</p>
+
+<p>The required amount of sulfuric acid should then be poured
+rather slowly into the water. <i>This process must never be reversed;
+that is, the acid must never be poured into the jar first.</i> The cyanid
+should be weighed and put into a paper bag beside the jar. All hats,
+coats, or other articles that will be needed before the work is over<span class="pagenum"><a name="Page_320" id="Page_320">[Pg 320]</a></span>
+should be removed from the room. When everything is ready the
+operator should drop the bag of cyanid gently into the jar, holding
+his breath, and should walk quickly out of the room. The steam-like
+gas does not rise immediately under these conditions, and ample
+time is given for the operator to walk out and shut the door. If
+preferred, however, the paper bag may be suspended by a string
+passing through a screw eye in the ceiling and then through the keyhole
+of the door. In this case the bag may be lowered from the outside
+after the operator has left the room and closed the door.</p>
+
+<p>The writer has most often started the fumigation toward evening
+and left it going all night, opening the doors in the morning. The
+work can be done, however, at any time during the day and should
+extend over a period of five or six hours at least. It is said that better
+results will be obtained in a temperature of 70° F., or above, than
+at a lower degree.</p>
+
+<p>At the close of the operation the windows and doors may be opened
+from the outside. In the course of two or three hours the gas should
+be dissipated enough to allow a person to enter the room without
+danger. The odor of the gas is like that of peach kernels and is easily
+recognized. The room should not be occupied until the odor has
+disappeared.</p>
+
+
+<h3><a name="Fumigating_a_Large_House" id="Fumigating_a_Large_House"></a><span class="smcap">Fumigating a Large House</span></h3>
+
+<p>The fumigation of a large house is merely a repetition, in each room
+and hall, of the operations already described for a single room. All
+the rooms should be made tight, and the proper quantities of water
+and sulfuric acid should be measured and poured into jars placed
+in each room with the cyanid in bags besides the jars. When all
+is ready, the operator should <i>go to the top floor and work downward</i>
+because the gas is lighter than air and tends to rise.</p>
+
+
+<h3><a name="Precautions" id="Precautions"></a><span class="smcap">Precautions</span></h3>
+
+<p>The cyanid should be broken up into small pieces not larger than
+small eggs. This can best be done on a cement or brick pavement.
+It would be advantageous to wear gloves in order to protect the hands,
+although the writer has broken many pounds of cyanid without any
+protection on the hands. Wash the hands thoroughly at frequent
+intervals in order to remove the cyanid.</p>
+
+<p>The operations of the work must be carried out according to
+directions.<span class="pagenum"><a name="Page_321" id="Page_321">[Pg 321]</a></span></p>
+
+<p>The work should be done by a calm, thoughtful and careful
+person&mdash;best by one who has had some experience.</p>
+
+<p>Conspicuous notices of what has been done should be placed on
+the doors, and the doors should be locked so that no one can stray
+into the rooms.</p>
+
+<p>The gas is lighter than air, therefore one should always begin in the
+rooms at the top of the house and work down.</p>
+
+<p>After fumigation is over the contents of the jar should be emptied
+into the sewer or some other safe place. The jars should be washed
+thoroughly before they are used again.</p>
+
+<p><i>It must be remembered that cyanid is a deadly poison</i>; but it is
+very efficient against household insects, if carefully used, and is not
+particularly dangerous when properly handled.</p>
+
+
+<h3><a name="LESIONS_PRODUCED_BY_THE_BITE_OF_THE_BLACK-FLY" id="LESIONS_PRODUCED_BY_THE_BITE_OF_THE_BLACK-FLY"></a>LESIONS PRODUCED BY THE BITE OF THE BLACK-FLY</h3>
+
+<p>While this text was in press there came to hand an important paper
+presenting a phase of the subject of black fly injury so different from
+others heretofore given that we deem it expedient to reproduce here
+the author's summary. The paper was published in <i>The Journal
+of Cutaneous Diseases</i>, for November and December, 1914, under the
+title of "A Clinical, Pathological and Experimental Study of the
+Lesions Produced by the Bite of the Black Fly (<i>Simulium venustum</i>),"
+by Dr. John Hinchman Stokes, of the University of Michigan.</p>
+
+
+<h3><span class="smcap">Resume and Discussion of Experimental Findings</span></h3>
+
+<p>The principal positive result of the work has been the experimental
+reproduction of the lesion produced by the black-fly in characteristic
+histological detail by the use of preserved flies. The experimental
+lesions not only reproduced the pathological pictures, but followed
+a clinical course, which in local symptomatology especially, tallied
+closely with that of the bite. This the writer interprets as satisfactory
+evidence that the lesion is not produced by any living infective
+agent. The experiments performed do not identify the nature
+of the toxic agent. Tentatively they seem to bring out, however,
+the following characteristics.</p>
+
+<p>1. The product of alcoholic extraction of flies do not contain
+the toxic agent.</p>
+
+<p>2. The toxic agent is not inactivated by alcohol.</p>
+
+<p>3. The toxic agent is not destroyed by drying fixed flies.</p>
+
+<p>4. The toxic agent is not affected by glycerin, but is, if anything,
+more active in pastes made from the ground fly and glycerin, than
+in the ground flies as such.<span class="pagenum"><a name="Page_322" id="Page_322">[Pg 322]</a></span></p>
+
+<p>5. The toxic agent is rendered inactive or destroyed by hydrochloric
+acid in a concentration of 0.25%.</p>
+
+<p>6. The toxic agent is most abundant in the region of the anatomical
+structures connected with the biting and salivary apparatus
+(head and thorax).</p>
+
+<p>7. The toxic agent is not affected by a 0.5% solution of sodium
+bicarbonate.</p>
+
+<p>8. The toxic agent is not affected by exposure to dry heat at
+100° C. for two hours.</p>
+
+<p>9. The toxic agent is destroyed or rendered inactive in alkaline
+solution by a typical hydrolytic ferment, pancreatin.</p>
+
+<p>10. Incomplete experimental evidence suggests that the activity
+of the toxic agent may be heightened by a possible lytic action of
+the blood serum of a sensitive individual, and that the sensitive serum
+itself may contain the toxic agent in solution.</p>
+
+<p>These results, as far as they go (omitting No. 10), accord with
+Langer's except on the point of alcoholic solubility and the effect
+of acids. The actual nature of the toxic agent in the black-fly is
+left a matter of speculation.</p>
+
+<p>The following working theories have suggested themselves to
+the writer. First, the toxin may be, as Langer believes in the case
+of the bee, an alkaloidal base, toxic as such, and neutralized after
+injection by antibodies produced for the occasion by the body. In
+such a case the view that a partial local fixation of the toxin occurs,
+which prevents its immediate diffusion, is acceptable. Through
+chemotactic action, special cells capable of breaking up the toxin
+into harmless elements are attracted to the scene. Their function
+may be, on the other hand, to neutralize directly, not by lysis.
+This would explain the rôle of the eosinophiles in the black-fly lesion.
+If their activities be essential to the destruction or neutralization
+of the toxin, one would expect them to be most numerous where
+there was least reaction. This would be at the site of a bite in an
+immune individual. A point of special interest for further investigation,
+would be the study of such a lesion.</p>
+
+<p>Second, it is conceivable that the injected saliva of the fly does
+not contain an agent toxic as such. It is possible, that like many
+foreign proteins, it only becomes toxic when broken down. The
+completeness and rapidity of the breaking down depends on the
+number of eosinophiles present. In such a case immunity should
+again be marked by intense eosinophilia.<span class="pagenum"><a name="Page_323" id="Page_323">[Pg 323]</a></span></p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_173" id="Fig_173"></a>
+<a href="images/f173-full.png"><img src="images/f173.png" width="400" height="299" alt="173. Fifth day mature lesion. Lower power drawing showing papillary &oelig;dema and infiltrate in the region
+of the puncture." title="173. Fifth day mature lesion. Lower power drawing showing papillary &oelig;dema and infiltrate in the region
+of the puncture." /></a>
+<span class="caption"><span title="add &quot;After Dr. J. H. Stokes&quot;">173. Fifth day mature lesion. Lower power drawing showing papillary &oelig;dema and infiltrate in the region
+of the puncture.</span></span>
+</div><p><span class="pagenum"><a name="Page_324" id="Page_324">[Pg 324]</a></span></p>
+
+<p>Third, lytic agents in the blood serum may play the chief rôle
+in the liberation of the toxic agent from its non-toxic combination.
+An immune individual would then be one whose immunity was not
+the positive one of antibody formation, but the negative immunity
+of failure to metabolize. An immune lesion in such a case might
+be conceived as presenting no eosinophilia, since no toxin is liberated.
+If the liberation of the toxin is dependent upon lytic agents present
+in the serum rather than in any cellular elements, a rational explanation
+would be available for the apparent results (subject to confirmation)
+of the experiment with sensitive and immune sera. In
+this experiment it will be recalled that the sensitive serum seemed to
+bring out the toxicity of the ground flies, and the serum itself seemed
+even to contain some of the dissolved or liberated toxin. The
+slowness with which a lesion develops in the case of the black-fly
+bite supports the view of the initial lack of toxicity of the injected
+material. The entire absence of early subjective symptoms, such
+as pain, burning, etc., is further evidence for this view. It would
+appear as if no reaction occurred until lysis of an originally non-toxic
+substance had begun. Regarding the toxin itself as the chemotactic
+agent which attracts eosinophiles, its liberation in the lytic
+process and diffusion through the blood stream attracts the cells
+in question to the point at which it is being liberated. Arriving
+upon the scene, these cells assist in its neutralization.</p>
+
+<p>The last view presented is the one to which the author inclines
+as the one which most adequately explains the phenomena.</p>
+
+<p>A fourth view is that the initial injection of a foreign protein by
+the fly (i.e., with the first bite) sensitizes the body to that protein.
+Its subsequent injection at any point in the skin gives rise to a
+local expression of systematic sensitization. Such local sensitization
+reactions have been described by Arthus and Breton, by Hamburger
+and Pollack and by Cowie. The description of such a lesion
+given by the first named authors, in the rabbit, however, does not
+suggest, histopathologically at least, a strong resemblance to that
+of the black-fly. Such an explanation of many insect urticariæ
+deserves further investigation, however, and may align them under
+cutaneous expressions of anaphylaxis to a foreign protein injected
+by the insect. Depending on the chemical nature of the protein
+injected, a specific chemotactic reaction like eosinophilia may or
+may not occur. Viewed in this light the development of immunity
+to insect bites assumes a place in the larger problem of anaphylaxis.<span class="pagenum"><a name="Page_325" id="Page_325">[Pg 325]</a></span></p>
+
+<div class="figcenter" style="width: 375px;"><a name="Fig_174" id="Fig_174"></a>
+<a href="images/f174-full.png"><img src="images/f174.png" width="375" height="477" alt="174. Experimental lesion produced from alcohol-fixed flies, dried and ground into a
+paste with glycerin." title="174. Experimental lesion produced from alcohol-fixed flies, dried and ground into a
+paste with glycerin." /></a>
+<span class="caption"><span title="add &quot;After Dr. J. H. Stokes&quot;">174. Experimental lesion produced from alcohol-fixed flies, dried and ground into a
+paste with glycerin.</span></span>
+</div><p><span class="pagenum"><a name="Page_326" id="Page_326">[Pg 326]</a></span></p>
+
+
+<h3><span class="smcap">Summary</span></h3>
+
+<p>In order to bring the results of the foregoing studies together,
+the author appends the following résumé of the clinical data presented
+in the first paper.</p>
+
+<p>The black-fly, <i>Simulium venustum</i>, inflicts a painless bite, with
+ecchymosis and hæmorrhage at the site of puncture. A papulo-vesicular
+lesion upon an urticarial base slowly develops, the full
+course of the lesion occupying several days to several weeks. Marked
+differences in individual reaction occur, but the typical course involves
+four stages. These are, in chronological order, the papular
+stage, the vesicular or pseudovesicular, the mature vesico-papular or
+weeping papular stage and the stage of involution terminating in a
+scar. The papule develops in from 3 to 24 hours. The early pseudovesicle
+develops in 24 to 48 hours. The mature vesico-papular lesion
+develops by the third to fifth day and may last from a few days to
+three weeks. Involution is marked by cessation of oozing, subsidence
+of the papule and scar-like changes at the site of the lesion. The
+symptoms accompanying this cycle consist of severe localized or
+diffused pruritus, with some heat and burning in the earlier stages
+if the &oelig;dema is marked. The pruritus appears with the pseudovesicular
+stage and exhibits extraordinary persistence and a marked
+tendency to periodic spontaneous exacerbation. The flies tend to
+group their bites and confluence of the developing lesions in such
+cases may result in extensive &oelig;dema with the formation of oozing
+and crusted plaques. A special tendency on the part of the flies
+to attack the skin about the cheeks, eyes and the neck along the
+hair line and behind the ears, is noted. In these sites inflammation
+and &oelig;dema may be extreme.</p>
+
+<p>A distinctive satellite adenopathy of the cervical glands develops
+in the majority of susceptible persons within 48 hours after being
+bitten in the typical sites. This adenopathy is marked, discrete
+and painful, the glands often exquisitely tender on pressure. It
+subsides without suppuration.</p>
+
+<p>Immunity may be developed to all except the earliest manifestations,
+by repeated exposures. Such an immunity in natives of an
+infested locality is usually highly developed. There are also apparently
+seasonal variations in the virulence of the fly and variations
+in the reaction of the same individual to different bites.</p>
+
+<p>Constitutional effects were not observed but have been reported.<span class="pagenum"><a name="Page_327" id="Page_327">[Pg 327]</a></span></p>
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="BIBLIOGRAPHY" id="BIBLIOGRAPHY"></a>BIBLIOGRAPHY</h2>
+
+
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+
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+
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+
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+
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+
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+
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+
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+
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+
+<p>---- 1911. Sulla transmissione delle Leishmaniosa. ibid., xx&nbsp;(1) p.&nbsp;50-51.</p>
+
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+
+<p>---- 1914. La meteorologia della leishmaniosi interna nel Mediterraneo.
+ibid., xxiii&nbsp;(1) p.&nbsp;625-629.</p>
+
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+
+<p><b>Beauperthuy, L.&nbsp;D.</b> 1853. (Cited by Boyce, 1909.)</p>
+
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+
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+
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+
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+p.&nbsp;1-28.</p>
+
+<p><b>Blackwell, J.</b> 1855. Experiments and observations on the poison of animals
+of the order Araneidea. London, Trans. Linn. Soc. xxi, 31-37.</p>
+
+<p><b>Blaizot, L.</b>, <b>Conseil, E.</b>, and <b>Nicolle, C.</b> 1913. Étiologie de la fièvre récurrente,
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+
+<p><b>Blanchard, R.</b> 1892. Sur les Oestrides américains dont la larve vit dans la
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+
+<p>---- 1898. Sur le pseudo-parasitisme des Myriapodes chez l'Homme.
+Arch. Parasit.&nbsp;1, p.&nbsp;452-490.</p>
+
+<p>---- 1902. Nouvelles observations sur le pseudo-parasitisme des Myriapodes
+chez l'homme. Arch. parasit. vi, p.&nbsp;245-256.</p>
+
+<p>---- 1905. Les moustiques. Histoire naturelle et médicale. 8vo. Paris,
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+
+<p>---- 1907. Parasitisme du <i>Dipylidium caninum</i> dans l'espéce humaine,
+à propos d'un cas nouveau. Arch. Parasit. ;xi, p.&nbsp;439-471.</p>
+
+<p><b>Blankmeyer, H.&nbsp;C.</b> 1914. Intestinal myiasis; with report of case. Journ.
+Amer. Med. Assoc. lxiii, p.&nbsp;321.</p>
+
+<p><b>Bordas, M. L.</b> 1905. Recherches anatomiques, histologiques et physiologiques
+sur les glandes venimeuses ou glandes des chélicères des malmignattes (<i>Lactrodectus
+13-guttatus</i> Rossi.) Ann. Sci. Nat. (ix&nbsp;ser) i, 147-164, 1&nbsp;pl. 4&nbsp;text
+fig.</p>
+
+<p><b>Borrell, A.</b> 1910. Parasitisme et Tumeurs. Ann Inst. Pasteur, xxiv, p.&nbsp;778-788.</p>
+
+<p><b>Boyce, R.</b> 1909. Mosquito or man? The conquest of the tropical world.
+8vo. London, Murray. (xvi&nbsp;+&nbsp;267&nbsp;p.).</p>
+
+<p><b>Brauer, F.</b> 1899. Beiträge zur Kenntniss der Muscaria schizomatopa. Sitzungsb.
+kais. Akad. Wissensch. Math.-Naturwiss. Klasse, cviii, p. 495-529.</p>
+
+<p><b>Brauer, F.</b> and <b>Bergenstamm, J.</b> 1889-1894. Die Zweiflügler des Kaiserl.
+Museum zu Wien. Denkschr. Kais. Akad. Wissensch. Math.-Naturwiss
+Klasse. lvi p.&nbsp;69-180; lviii, p.&nbsp;305-446; lx, p.&nbsp;89-240; lxi, p.&nbsp;537-624.</p>
+
+<p><b>Braun, M.</b> 1908. Die tierischen Parasiten des Menschen. 4&nbsp;Aufl. 8vo.
+Würzburg, Kabitzsch. (ix&nbsp;+&nbsp;623&nbsp;p.). Also,</p>
+
+<div class="hanging">
+<p>Eng. Trans. of 3d&nbsp;ed., with additions by Sambon and Theobald.</p>
+</div>
+
+<p><b>Briot, A.</b> 1904. Sur le venin de scolopendres. C.&nbsp;R. Soc. Biol. Paris. lvi, p.&nbsp;476-477.</p>
+
+<p><b>Bruce, D.</b> 1907. Trypanosomiases. Osler's Modern Med. Philadelphia,
+Lea Bros. &amp;&nbsp;Co. i, p.&nbsp;460-487.</p>
+
+<p><b>Bruck, C.</b> 1911. Ueber das Gift der Stechmücke. Deutsche medizin. Wochenschr.
+28 Sept. 1911, p.&nbsp;1787-1790.</p>
+
+<p><b>Brues, C.&nbsp;T.</b> 1913. The relation of the stable-fly (<i>Stomoxys calcitrans</i>) to the
+transmission of infantile paralysis. Journ. Econ. Ent. vi, p.&nbsp;101-109.</p>
+
+<p><b>Brues, C.&nbsp;T.</b> and <b>Sheppard, P.&nbsp;A.&nbsp;E.</b> 1912. The possible etiological relation
+of certain biting insects to the spread of infantile paralysis. Journ. Econ.
+Ent.&nbsp;v, p.&nbsp;305-324.</p>
+
+<p><b>Brumpt, E.</b> 1905. Maladie du sommeil. Distribution géographique, étiologie,
+prophylaxie. Arch. Parasit.&nbsp;ix, p.&nbsp;205-224.</p>
+
+<p>---- 1913. Précis de parasitologie. 2&nbsp;ed. 8<sup>o</sup>. Paris, Masson &amp; Cie. (xxviii
++&nbsp;1011&nbsp;p.).</p>
+
+<p><b>Brunetti, E.</b> 1912. Description of <span title="for Apiochæta read Aphiochæta"><a name="AC_25" id="AC_25"></a>Apiochæta</span> ferruginea, a hitherto undescribed
+species of Phoridæ that causes myasis in man. Rec. Indian Mus. vii p.&nbsp;83-86.</p>
+
+<p><b>Bugnion, E.</b> and <b>Popoff, N.</b> 1908. L'appareil salivaire des hémiptères. Arch.
+d'anatomie micr. x, p.&nbsp;227-456.</p>
+
+<p>---- 1911. Les piéces buccales des Hémiptères. Arch. Zool. Exper. (5)
+vii, p.&nbsp;643-674.<span class="pagenum"><a name="Page_329" id="Page_329">[Pg 329]</a></span></p>
+
+<p><b>Calandruccio, S.</b> 1899. Sul pseudo-parassitismo delle larve dei Ditteri nell'intestino
+umano. Arch. Parasit. ii, p.&nbsp;251-257.</p>
+
+<p><b>Calkins, G.&nbsp;N.</b> 1909. Protozoology. New York, Lea and Febiger (349&nbsp;p.).</p>
+
+<p><b>Castellani, A.</b> and <b>Chalmers, A.&nbsp;J.</b> 1910. Manual of tropical medicine 4<sup>o</sup>.
+New York. Wm. Wood &amp;&nbsp;Co. (xxv +&nbsp;1242&nbsp;p.). 2&nbsp;ed., 1914.</p>
+
+<p><b>Celli, A.</b> 1886. Acque potabile e malaria. Giornale della Società italiana di
+igiene.</p>
+
+<p>---- 1900. Malaria according to the new researches. Eng. trans. 2 ed.
+8vo. London, Longmans, Green &amp;&nbsp;Co. (xxiv +&nbsp;275&nbsp;p.).</p>
+
+<p><b>Chevril, R.</b> 1909. Sur la myiase des voies urinaires. Arch. Parasit. xii, p.&nbsp;369-450.</p>
+
+<p><b>Chittenden, F.&nbsp;H.</b> 1906. Harvest mites or "chiggers". U.&nbsp;S. Dept. Agric.
+Bur. Ent. Circ. No.&nbsp;77, p.&nbsp;1-6.</p>
+
+<p><b>Cholodkovsky, N.</b> 1904. Zur Kentniss der Mundwerkzeuge und Systematik
+der Pediculiden. Zool. Anz. xxviii, p.&nbsp;368-370.</p>
+
+<p>---- 1905. Noch ein Wort über die Mundeile der Pediculiden. ibid., xxix
+p.&nbsp;149.</p>
+
+<p><b>Christophers, S.&nbsp;R.</b> 1907. <i>Piroplasma canis</i> and its life cycle in the tick.
+Sci. Mem. Med. Ind., Calcutta, n.&nbsp;s. xxix, p.&nbsp;1-83.</p>
+
+<p>---- 1912. The development of <i>Leucocytozoon canis</i> in the tick, with a
+reference to the development of <i>Piroplasma</i>. Parasitology, v, p.&nbsp;37-48.</p>
+
+<p><b>Coates, G.&nbsp;M.</b> 1914. A case of myasis aurium accompanying the radical
+mastoid operation. Journ. Amer. Med. Assoc. lxiii, p.&nbsp;479.</p>
+
+<p><b>Comstock, J.&nbsp;H.</b> 1912. The spider book. A manual for the study of the
+spiders and their near relatives found in America north of Mexico. Large
+8vo. New York, Doubleday, Page &amp;&nbsp;Co. (xv +&nbsp;721&nbsp;p., 771&nbsp;figs.)</p>
+
+<p><b>Comstock, J.&nbsp;H.</b> and <b>A.&nbsp;B.</b> 1914. A manual for the study of insects. 12th&nbsp;ed.
+8<sup>o</sup>. Ithaca, N.&nbsp;Y. (x +&nbsp;701&nbsp;p., 797 text figs. and 6&nbsp;pls.).</p>
+
+<p><b>Cook, F,&nbsp;C.</b>, <b>Hutchison, R.&nbsp;H.</b> and <b>Scales, F.&nbsp;M.</b> 1914. Experiments in the
+destruction of fly larvæ in horse manure. U.&nbsp;S. Dept. Agric. Bul.&nbsp;118,
+p.&nbsp;1-26.</p>
+
+<p><b>Copeman, S.&nbsp;M., Howlett, F.&nbsp;M.</b> and <b>Merriman, G.</b> 1911. An experimental
+investigation on the range of flight of flies. Rept. to the Local Gov't Board on
+Publ. Health. n.&nbsp;s. liii, p.&nbsp;1-9.</p>
+
+<p><b>Coquillett, D.&nbsp;W.</b> 1906. A classification of the mosquitoes of North and Middle
+North America. U.&nbsp;S. Dept. Agric. Bur. Ent. Tech. Bul. xi, p.&nbsp;1-31.</p>
+
+<p>---- 1907. Discovery of blood-sucking Psychodidæ in America. Ent.
+News xviii, p.&nbsp;101-102.</p>
+
+<p><b>Cox, G.&nbsp;L.</b>, <b>Lewis, F.&nbsp;C.</b> and <b>Glynn, E.&nbsp;F.</b> 1912. The numbers and varieties
+of bacteria carried by the common housefly in sanitary and insanitary city
+areas. Journ. Hygiene, xii, p.&nbsp;290-319.</p>
+
+<p><b>Crampton, G.&nbsp;C.</b> 1914. On the misuse of the terms parapteron, hypopteron,
+tegula, squamula, patagium and scapula. Journ. N.&nbsp;Y. Ent. Soc. xxii, p.&nbsp;248-261.</p>
+
+<p><b>Currie, D.&nbsp;H.</b> 1910. Mosquitoes in relation to the transmission of leprosy.
+Flies in relation to the transmission of leprosy. Public Health Bul. Washington,
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+
+<p><b>Dahl, Fr.</b> 1910. Milben als Erzeuger von Zellwucherungen. Centralbl.
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+
+<p><b>Dalla Torre, Dr. K.&nbsp;von.</b> 1908. Anoplura. Genera Insectorum. Fasc.&nbsp;81,
+p.&nbsp;1-22.</p>
+
+<p><b>Darling, S.&nbsp;T.</b> 1913. The part played by flies and other insects in the spread
+of infectious diseases in the tropics, with special reference to ants and to the
+transmission of Tr.&nbsp;hippicum by <i>Musca domestica</i>. Trans. 15th Intern.
+Congress on Hygiene and Demography, Washington, iv, p.&nbsp;182-185.</p>
+
+<p><b>Doane, R.&nbsp;W.</b> 1910. Insects and disease. 8vo. New York, Holt &amp;&nbsp;Co.
+(xiv +&nbsp;227&nbsp;p.).</p>
+
+<p><b>Doerr, H.</b> and <b>Russ, V.</b> 1913. Die Phlebotomen. In Mense's Handbuch der
+Tropenkrankheiten, i, p.&nbsp;263-283, pls.&nbsp;11-12.</p>
+
+<p><b>Doflein, F.</b> 1911. Lehrbuch der Protozoenkunde, 3&nbsp;ed. 4<sup>o</sup>. Jena. G.&nbsp;Fischer
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+
+<p><b>Dufour, L.</b> 1833. Recherches anatomiques et physiologiques sur les Hémiptères.
+Mém d.&nbsp;savant etrang. à l'Acad. d. Sc. iv, p.&nbsp;129-462.</p>
+
+<p><b>Duges, A.</b> 1836. Observations sur les Aranéides. Ann. sci. nat. (zool.)
+Paris. (Sér&nbsp;2) vi, 159-218.</p>
+
+<p><b>Dutton, J.&nbsp;E.</b> and <b>Todd, J.&nbsp;L.</b> 1905. The nature of human tick fever in the
+eastern part of the Congo Free State, with notes on the distribution and
+bionomics of the tick. Liverpool School Trop. Med. Mem. xvii, p.&nbsp;1-18.</p>
+
+<p><b>Dyar, H.&nbsp;G.</b> 1906. Key to the known larvæ of the mosquitoes of the United
+States U. S. Dept. Agric. Bur. Ent. Circ.&nbsp;72, p.&nbsp;1-6.</p>
+
+<p><b>Dyar</b>, See Howard, Dyar and Knab.</p>
+
+<p><b>Dziedzicki.</b> See Schnabl.</p>
+
+<p><b>Enderlein, G.</b> 1901. Zur Kenntniss der Flöhe und Sandflöhe. Zool. Jahrb.
+(Syst.) xiv, p.&nbsp;548-557, pl.&nbsp;34.</p>
+
+<p>---- 1904. Lause-Studien. Ueber die Morphologie, Klassifikation und
+systematische Stellung der Anopluren, nebst Bemerkungen zur Systematik
+der Insektenordnungen. Zool. Anz. xxviii, p.&nbsp;121-147.</p>
+
+<p><b>Esten, W.&nbsp;M.</b> and <b>Mason, C.&nbsp;J.</b> 1908. Sources of bacteria in milk. Storrs
+Agric. Exp. Sta. Bul. li, p.&nbsp;65-109.</p>
+
+<p><b>Ewing, H.&nbsp;E.</b> 1912. The origin and significance of parasitism in the Acarina.
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+
+<p><b>Eysell, A.</b> 1913. Die Krankheitsereger und Krankheitsüberträger unter den
+Arthropoden. See, Mense (1913).</p>
+
+<p><b>Felt, E.&nbsp;P.</b> 1904. Mosquitoes or Culicidæ of New York State. N.&nbsp;Y. State
+Museum. Bul.&nbsp;79. p.&nbsp;241-391. 57&nbsp;plates.</p>
+
+<p>---- 1913. Queen Blow-fly. Georgian flesh-fly. 28th rept. of the State
+Entomologist. p.&nbsp;75-92.</p>
+
+<p><b>Finlay, Charles J.</b> 1881 et seq. Trabajos selectos. Selected papers. Republica
+de Cuba. Secretaria de Sanidad y Beneficencia. Havana 1912. xxxiv +
+657&nbsp;p.</p>
+
+<p><b>Forbes, S.&nbsp;A.</b> 1912. On black-flies and buffalo-gnats, (<i>Simulium</i>), as possible
+carriers of pellagra in Illinois. 27th Rept. of the State Entomologist of
+Illinois, p.&nbsp;21-55.</p>
+
+<p><b>Forel, A.</b> 1878. Der Giftapparat und die Analdrüsen der Ameisen. Zeitschr.
+wiss. Zool. xxx, p.&nbsp;28-68.</p>
+
+<p><b>Fox, G.&nbsp;H.</b> 1880. Photographic illustrations of skin disease. 4<sup>o</sup>. New York,
+E.&nbsp;B. Treat.</p>
+
+<p><b>Fracker, S.&nbsp;B.</b> 1914. A systematic outline of the Reduviidæ of North America.
+Iowa Acad. Sci. p.&nbsp;217-252.</p>
+
+<p><b>French, G.&nbsp;H.</b> 1905. <i>Nitidula bipustulata</i> in a new rôle. Canadian Entomologist,
+xxxvii, p.&nbsp;420.</p>
+
+<p><b>Frost, W.&nbsp;H.</b> 1911. Acute anterior poliomyelitis (<i>Infantile paralysis</i>). A
+précis. Public Health Bul. Washington. No.&nbsp;44, p.&nbsp;1-52.</p>
+
+<p><b>Fuller, C.</b> 1914. The skin maggot of man. S.&nbsp;African Agric. Journ. vii, p.&nbsp;866-874.</p>
+
+<p><b>Galli-Valerio, B.</b> 1908. Le rôle des arthropodes dans la dissemination des
+maladies. Centralbl. Bakt. 1 Abt. Ref. xli, p.&nbsp;353-360.</p>
+
+<p><b>Gerhardt, C.</b> 1884. Ueber Intermittensimpfungen. Zeitschr. f.&nbsp;klin. Med.
+vii, p.&nbsp;372.</p>
+
+<p><b>Girault, A.&nbsp;A.</b> 1905-06. The bed-bug, Clinocoris, (=&nbsp;<i>Cimex</i> =&nbsp;<i>Acanthia</i> =&nbsp;<i>Klinophilos</i>)
+<i>lectularia</i> Linnæus. Psyche xii, p.&nbsp;61-74, vol.&nbsp;xiii, p.&nbsp;42-58.</p>
+
+<p>---- 1910-14 Preliminary studies on the biology of the bed-bug, <i>Cimex
+lectularius</i>, Linn. Jour. Econ. Biol. v, p.&nbsp;88-91; vii, p.&nbsp;163-188; ix, p.&nbsp;25-45.</p>
+
+<p><b>Girault, A.&nbsp;A.</b> and <b>Strauss, J.&nbsp;F.</b> 1905. The bed-bug, <i>Clinocoris lectularius</i>
+(Linnæus) and the fowl bug, <i>Clinocoris columbarius</i> (Jenyns): host relations.
+Psyche, xii, p.&nbsp;117-123.</p>
+
+<p><b>Girschner, E.</b> 1893. Beitrag zur Systematik der Musciden. Berliner Ent.
+Zeitschr. xxxviii, p.&nbsp;297-312.</p>
+
+<p>---- 1896. Ein neues Musciden-System auf Grund der Thoracalbeborstung
+und der Segmentierung des Hinterleibes. Wochenschr. für Entom.&nbsp;i, p.&nbsp;12-16,
+30-32, 61-64, 105-112.<span class="pagenum"><a name="Page_331" id="Page_331">[Pg 331]</a></span></p>
+
+<p><b>Goeldi, E.&nbsp;A.</b> 1913. Die sanitarisch-pathologische Bedeutung der Insekten
+und verwandten Gliedertiere 8<sup>o</sup>. Berlin. Friedländer &amp;&nbsp;Sohn. (155&nbsp;p.).</p>
+
+<p><b>Goldberger, J.</b> 1910. The straw itch. (Dermatitis Schambergi). Public
+Health Repts., Washington, xxv, p.&nbsp;779-784.</p>
+
+<p><b>Goldberger, J.</b> and <b>Anderson, J.&nbsp;F.</b> 1912, The transmission of typhus fever,
+with especial reference to transmission by the head-louse (<i>Pediculus capitis</i>).
+Public Health Repts., Washington, xxvii, p.&nbsp;297-307.</p>
+
+<p><b>Goldberger, J.</b>, <b>Waring, C.&nbsp;H.</b>, and <b>Willets, D.&nbsp;G.</b> 1914. The treatment and
+prevention of pellagra. Public Health Repts., Washington, xxix, p.&nbsp;2821-2826.</p>
+
+<p><b>Graham-Smith, G.&nbsp;S.</b> 1913. Flies in relation to disease: non-bloodsucking
+flies. 8vo. Cambridge Univ. Press. (xiv +&nbsp;292&nbsp;p.)</p>
+
+<p><b>Grassi, B.</b> 1907. Ricerche sui Flebotomi. Memorie della Società ital. della
+Scienze, ser. 3&nbsp;a, xiv, p.&nbsp;353-394, pls.&nbsp;i-iv.</p>
+
+<p><b>Grassi, B.</b> and <b>Noe, G.</b> 1900. Propagation of the filariæ of the blood exclusively
+by means of the puncture of peculiar mosquitoes. British Med. Journ.&nbsp;ii,
+p.&nbsp;1306-1307.</p>
+
+<p><b>Griffith, A.</b> 1908. Life history of house-flies. Public Health, xxi, p.&nbsp;122-127.</p>
+
+<p><b>Grünberg, K.</b> 1907. Die blutsaugenden Dipteren. 8vo. Jena, Fischer.
+(vi +&nbsp;188&nbsp;p.).</p>
+
+<p><b>Hadwen, S.</b> 1913. On "tick paralysis" in sheep and man following bites of
+<i>Dermacentor venustus</i>. Parasitology, vi, p.&nbsp;283-297.</p>
+
+<p><b>Hadwen, S.</b> and <b>Nuttall, G.&nbsp;H.&nbsp;F.</b> 1913. Experimental "tick paralysis" in the
+dog. Parasitology, vi, p.&nbsp;298-301.</p>
+
+<p><b>Hall, M.&nbsp;C.</b> and <b>Muir, J.&nbsp;F.</b> 1913. A critical study of a case of myasis due to
+<i>Eristalis</i>. Arch. Int. Med., Chicago, xi, p.&nbsp;193-203.</p>
+
+<p><b>Hamilton, J.</b> 1893. Medico-entomology. Entom. News&nbsp;iv, p.&nbsp;217-219.</p>
+
+<p><b>Hart, C.&nbsp;A.</b> 1895. On the entomology of the Illinois river and adjacent waters.
+Bul. Ill. State Lab. Nat. Hist., iv, p.&nbsp;149-273.</p>
+
+<p><b>Headlee, T.&nbsp;J.</b> 1914. Anti-mosquito work in New Jersey. Jour. Econ. Ent.
+vii, p.&nbsp;260-268.</p>
+
+<p><b>Hecker, J.&nbsp;F.&nbsp;C.</b> 1885. The dancing mania of the Middle Ages. Transl. by
+B.&nbsp;G. Bahington. 8vo. New York, Humboldt Library. (53p.).</p>
+
+<p><b>Hendel.</b> 1901. Beitrag zur Kenntniss der Calliphorinen. Wiener Ent. Zeitung.
+xx, p.&nbsp;28-33.</p>
+
+<p><b>Herms, W.&nbsp;B.</b> 1911. The housefly in its relation to public health. Cal. Agric.
+Exp. Sta. Bul.&nbsp;215, p.&nbsp;511-548.</p>
+
+<p>---- 1913. Malaria: cause and control. 8<sup>o</sup>. New York, Macmillan Co.
+(xi +&nbsp;163&nbsp;p.).</p>
+
+<p><b>Herrick, G.&nbsp;W.</b> 1903. The relation of malaria to agriculture and other industries
+of the South. Pop. Sci. Mo. lxii, p.&nbsp;521-525.</p>
+
+<p>---- 1913. Household insects and methods of control. Cornell Reading
+Course, (N.&nbsp;Y. State College of Agric.), iii, 47&nbsp;p.</p>
+
+<p>---- 1914. Insects injurious to the household and annoying to man. 8vo.
+New York, Macmillan Co. (xvii +&nbsp;470).</p>
+
+<p><b>Hewitt, C.&nbsp;G.</b> 1910. The house-fly. A study of its structure, development,
+bionomics, and economy. 8vo. Manchester Univ. Press. (xiv +&nbsp;196&nbsp;p.).</p>
+
+<p>---- 1912. <i>Fannia</i> (<i>Homalomyia</i>) <i>canicularis</i> Linn. and <i>F.&nbsp;scalaris</i> Fab.
+Parasitology, v. p.&nbsp;161-174.</p>
+
+<p><b>Heymons, R.</b> 1901. Biologische Beobachtungen an asiatischen Solifugen,
+nebst Beiträge zur Systematik derselben. Abl. Ak. Berlin, 1901, Anh.&nbsp;i,
+1-65&nbsp;p.</p>
+
+<p><b>Higgins, F.&nbsp;W.</b> 1891. Dipterous larvæ vomited by a child. Insect Life,
+Washington. iii, p.&nbsp;396-397.</p>
+
+<p><b>Hindle, E.</b> 1911&nbsp;a. The relapsing fever of tropical Africa. A Review. Parasitology,
+iv, p.&nbsp;183-203.</p>
+
+<p>---- 1911&nbsp;b. On the life cycle of <i>Spirochæta gallinarum</i>. ibid., iv. p.&nbsp;463-477.</p>
+
+<p><b>Hindle, E.</b> and <b>Merriman, G.</b> 1914. The range of flight of <i>Musca domestica</i>.
+Journ. of Hygiene, xiv. p.&nbsp;23-45.<span class="pagenum"><a name="Page_332" id="Page_332">[Pg 332]</a></span></p>
+
+<p><b>Hine, J.&nbsp;S.</b> 1903. Tabanidæ of Ohio. Papers Ohio Acad. Sci. No.&nbsp;5, 55&nbsp;p.</p>
+
+<p>---- 1906. Habits and life-histories of some flies of the family Tabanidæ.
+U.&nbsp;S. Dept. Agric. Bur. Ent. tech. bul.&nbsp;12, p.&nbsp;19-38.</p>
+
+<p>---- 1907. Second report upon the horse-flies of Louisiana. La. Stat. Exp.
+Bul.&nbsp;93, p.&nbsp;1-59.</p>
+
+<p><b>Hodge, C.&nbsp;F.</b> 1910. A practical point in the study of the typhoid, or filth-fly.
+Nature Study Review, vi, p.&nbsp;195-199.</p>
+
+<p>---- 1913. The distance house-flies, blue-bottles, and stable flies may
+travel over water. Science, n.&nbsp;s. xxxviii, p.&nbsp;513.</p>
+
+<p><b>Honeij, J.&nbsp;A.</b> and <b>Parker, R.&nbsp;R.</b> 1914. Leprosy: flies in relation to the transmission
+of the disease. Journ. Med. Research, Boston, xxx, p.&nbsp;127-130.</p>
+
+<p><b>Hooker, W.&nbsp;A.</b> 1908&nbsp;a. Life history, habits, and methods of study of the
+Ixodoidea. Jour. Econ. Ent.&nbsp;i, p.&nbsp;34-51.</p>
+
+<p>---- 1908&nbsp;b. A review of the present knowledge of the rôle of ticks in the
+transmission of disease. ibid., i, p.&nbsp;65-76.</p>
+
+<p><b>Hope, F.&nbsp;W.</b> 1837. On insects and their larvæ occasionally found in the human
+body. Trans. Ent. Soc., London, ii, p.&nbsp;256-271.</p>
+
+<p><b>Hough, G. de&nbsp;N.</b> 1899&nbsp;a. Synopsis of the Calliphorinæ of the United States.
+Zoological Bulletin, ii, p.&nbsp;283-290.</p>
+
+<p>---- 1899 b. Some Muscinæ of North America, Biological Bulletin&nbsp;i,
+p.&nbsp;19-33.</p>
+
+<p>---- 1899&nbsp;c. Some North American Genera of Calliphorinæ. Entom.
+News, x, p.&nbsp;62-66.</p>
+
+<p><b>Hovarth, G.</b> 1912. Revision of the American Cimicidæ. Ann. Mus. Nat.
+Hungarici, x, p.&nbsp;257-262.</p>
+
+<p><b>Howard, C.&nbsp;W.</b> 1908. A list of the ticks of South Africa, with descriptions and
+keys to all the forms known. Ann. Transvaal Mus.&nbsp;1, p.&nbsp;73-170.</p>
+
+<p><b>Howard, C.&nbsp;W.</b> and <b>Clark, P.&nbsp;F.</b> 1912. Experiments on insect transmission
+of the virus of poliomyelitis. Journ. Exper. Med. xvi, p.&nbsp;805-859.</p>
+
+<p><b>Howard, L.&nbsp;O.</b> 1899. Spider bites and kissing bugs. Pop. Sci. Mo.&nbsp;lv, p.&nbsp;31-42.</p>
+
+<p>---- 1900. A contribution to the study of the insect fauna of human excrement.
+Proc. Wash. Acad. Sci.&nbsp;ii, p.&nbsp;541-604.</p>
+
+<p>---- 1901. Mosquitoes, how they live, how they carry disease, how they are
+classified, how they may be destroyed. 8vo. New York, Doubleday,
+Page &amp;&nbsp;Co. (xv +&nbsp;241&nbsp;p.)</p>
+
+<p>---- 1909. Economic loss to the people of the United States, through insects
+that carry disease. U.&nbsp;S. Dept. Agric. Bur. of Ent. Bul.&nbsp;78, p.&nbsp;1-40.</p>
+
+<p><b>Howard, L.&nbsp;O.</b>, <b>Dyar, H.&nbsp;G.</b> and <b>Knab, F.</b> 1913-. The mosquitoes of North
+and Central America and the West Indies. Vol.&nbsp;I. A general consideration
+of mosquitoes, their habits, and their relations to the human species. 4<sup>o</sup>.
+Carnegie Institution of Washington (vii +&nbsp;520&nbsp;p.).</p>
+
+<p><b>Howard, L.&nbsp;O.</b> and <b>Marlatt, C.&nbsp;L.</b> 1902. The principal household insects of
+the United States. U.&nbsp;S. Dept. Agric., Bur. Ent. Bul.&nbsp;4.</p>
+
+<p><b>Huebner, W.</b> 1907. Ueber das Pfeilgift der Kalahari. Arch. exper. Path.
+und Pharm., lvii, p.&nbsp;358-366.</p>
+
+<p><b>Hunter, S.&nbsp;J.</b> 1913. Pellagra and the sand-fly. Jour. econ. Ent.&nbsp;vi, p.&nbsp;96-99.</p>
+
+<p><b>Hunter, W.&nbsp;D.</b> 1913. American interest in medical entomology. Jour. econ.
+Ent.&nbsp;vi, p.&nbsp;27-39.</p>
+
+<p><b>Hunter, W.&nbsp;D.</b> and <b>Bishopp, F.&nbsp;C.</b> 1910. Some of the more important ticks of
+the United States. U.&nbsp;S. Dept. Agric. Yearbook 1910, p.&nbsp;219-230, pls.&nbsp;xv-xvi.</p>
+
+<p>---- 1911. The Rocky Mountain spotted fever tick. With special reference
+to the problem of its control in the Bitter Root Valley in Montana.
+U.&nbsp;S. Dept. Agric., Bur. Ent. Bul.&nbsp;105, p.&nbsp;1-47.</p>
+
+<p><b>Hutchison, R.&nbsp;H.</b> 1914. The migratory habit of housefly larvæ as indicating
+a favorable remedial measure. An account of progress. U.&nbsp;S. Dept. Agric.,
+Bul.&nbsp;14, p.&nbsp;1-11.</p>
+
+<p><b>Jennings, A.&nbsp;H.</b> 1914. Summary of two years' study of insects in relation to
+pellagra. Journ. of Parasitology, i, p.&nbsp;10-21.<span class="pagenum"><a name="Page_333" id="Page_333">[Pg 333]</a></span></p>
+
+<p><b>Jennings, A.&nbsp;H.</b> and <b>King, W.&nbsp;V.</b> 1913. One of the possible factors in the
+causation of pellagra. Journ. Amer. Med. Assoc., lx, p.&nbsp;271-274.</p>
+
+<p><b>Jepson, F.&nbsp;P.</b> 1909. Notes on colouring flies for purposes of identification.
+Rep't to the Local Gov't Board on Publ. Health, n.&nbsp;s. 16, p.&nbsp;4-9.</p>
+
+<p><b>Johannsen, O.&nbsp;A.</b> 1903. Aquatic Nematocerous Diptera. N.&nbsp;Y. State Mus.
+Bul., 68, p.&nbsp;328-448, pls.&nbsp;32-50.</p>
+
+<p>---- 1905. Aquatic Nematocerous Diptera&nbsp;II. (Chironomidæ). ibid. 86,
+p.&nbsp;76-330, pls.&nbsp;16-37.</p>
+
+<p>---- 1908. North America Chironomidæ. ibid., 124, p.&nbsp;264-285.</p>
+
+<p>---- 1911. The typhoid fly and its allies. Maine Agric. Exp. Sta. Bul.,
+401, p.&nbsp;1-7.</p>
+
+<p>---- 1911. Simulium and pellagra. Insect Notes for 1910. Maine Agr.
+Exper. Station. Bul, 187, p.&nbsp;4.</p>
+
+<p><b>Kellogg, V.&nbsp;L.</b> 1915. Spider poison. Jour. of Parasitology, i, p.&nbsp;107+</p>
+
+<p><b>Kelly, H.&nbsp;A.</b> 1907. Walter Reed and yellow fever. 8vo. New York, McClure,
+Phillips &amp;&nbsp;Co. (xix +&nbsp;310&nbsp;p.).</p>
+
+<p><b>Kephart, Cornelia&nbsp;F.</b> 1914. The poison glands of the larva of the browntail
+moth (Euproctis chrysorrhoea Linn.). Journ. Parasit., i, p.</p>
+
+<p><b>Kieffer, J.&nbsp;J.</b> 1906. Chironomidæ. Genera Insectorum. Fasc.&nbsp;42, p.&nbsp;1-78.</p>
+
+<p>---- 1913. Nouv. étude sur les Chironomides de l'Indien Museum de
+Calcutta. Records of the Indian Mus., ix, p.&nbsp;119-197.</p>
+
+<p><b>King, A.&nbsp;F.&nbsp;A.</b> 1883. Insects and disease&mdash;mosquitoes and malaria. Pop.
+Sci. Mo. xxiii, p.&nbsp;644-658.</p>
+
+<p><b>Kirkland, A.&nbsp;H.</b> 1907. Second annual report of the Superintendent for suppressing
+the gypsy and browntail moths. 8vo. Boston. 170&nbsp;p.</p>
+
+<p><b>Kleine, E.</b> 1909. Postive Infektionsversuche mit <i>Trypanosoma brucei</i> durch
+<i>Glossina palpalis.</i> Deutsche med. Wochenschr., xxxv, p.&nbsp;469-470.</p>
+
+<div class="hanging"><p>Weitere wissenschaftliche Beobachtungen über die Entwicklung von Trypanosomen
+in Glossinen. ibid. p.&nbsp;924-925.</p>
+
+<p>Weitere Untersuchungen über die Ætiologie der Schlafkrankheit. ibid., p.&nbsp;1257-1260.</p>
+
+<p>Weitere Beobachtungen über Tsetsefliegen und Trypanosomen. ibid., p.&nbsp;1956-1958.</p></div>
+
+<p><b>Kling, C.</b> and <b>Levaditi, C.</b> 1913. Études sur la poliomyélite aiguë épidémique.
+Ann. Inst. Pasteur, xxvii, p.&nbsp;718-749, 739-855.</p>
+
+<p><b>Knab, F.</b> 1912. Unconsidered factors in disease-transmission by blood-sucking
+insects. Journ. Econ. Ent., v, p.&nbsp;196-200.</p>
+
+<p>---- 1913&nbsp;a. The species of Anopheles that transmit human malaria.
+Amer. Journ. Trop. Dis. and Preventive Med., i, p.&nbsp;24-43.</p>
+
+<p>---- 1913&nbsp;b. Anopheles and malaria. ibid., i, p.&nbsp;217.</p>
+
+<p>---- 1913&nbsp;c. The life history of <i>Dermatobia hominis</i>. ibid., i, p.&nbsp;464-468.</p>
+
+<p><b>Knab, F.</b> See Howard, Dyar, and Knab.</p>
+
+<p><b>Kobert, R.</b> 1893. Lehrbuch der Intoxikationen. 4<sup>o</sup>. Stuttgart, Enke.
+(xxii +&nbsp;816&nbsp;p.). 2d&nbsp;ed. in 2&nbsp;vols., 1906.</p>
+
+<p>---- 1901. Beiträge zur Kenntniss der Giftspinnen. 8<sup>o</sup>. Stuttgart, Enke.
+(viii +&nbsp;191&nbsp;p.).</p>
+
+<p><b>Kolbe, H.&nbsp;J.</b> 1894. Der Pfeilgiftkäfer der Kalahari-Wüste, <i>Diamphidia simplex</i>.
+Stett. Ent. Zeitg., iv, p.&nbsp;79-86.</p>
+
+<p><b>Krause, M.</b> 1907. Untersuchungen über Pfeilgifte aus unseren africanischen
+Kolonien. Verhand. deutsche Kolonien kong. 1905. p.&nbsp;264-288.</p>
+
+<p><b>Lallier, P.</b> 1897. Étude sur la myase du tube digestif chez l'homme. Thesis,
+Paris, 8<sup>o</sup>. 120&nbsp;p.</p>
+
+<p><b>Langer, J.</b> 1897. Ueber das Gift unserer Honigbiene. Archiv. exper. Path.
+und Pharm., xxxviii, p.&nbsp;381-396.</p>
+
+<p><b>Lavinder, C.&nbsp;H.</b> 1911. Pellagra: a précis. U.&nbsp;S. Publ. Health Service Bul.
+48, 37&nbsp;p.</p>
+
+<p><b>Leidy, J.</b> 1847. History and anatomy of the hemipterous genus <i>Belostoma</i>.
+Journ. Acad. Philad.&nbsp;(2), i, p.&nbsp;57-67.</p>
+
+<p><b>Leiper, R.&nbsp;T.</b> 1907. The etiology and prophylaxis of dracontiasis. British
+Med. Journ. 1907, p.&nbsp;129-132.<span class="pagenum"><a name="Page_334" id="Page_334">[Pg 334]</a></span></p>
+
+<p><b>Leishman, W.&nbsp;B.</b> 1910&nbsp;a. Observations on the mechanism of infection in tick
+fever and on the hereditary transmission of <i>Spirochæta duttoni</i> in the tick.
+Trans. Soc. Trop. Med. Hyg., iii, p.&nbsp;77-95. Abstr. in Bul. Inst. Pasteur,
+viii, p.&nbsp;312-313.</p>
+
+<p>---- 1910&nbsp;b. On the hereditary transmission and mechanism of infection
+in tick fever and on the hereditary transmission of <i>Spirochæta duttoni</i> in
+the tick. Lancet., clxxvii, p.&nbsp;11.</p>
+
+<p><b>Linnell, R.&nbsp;McC.</b> 1914. Notes on a case of death following the sting of a scorpion.
+Lancet, 1914, p.&nbsp;1608-1609.</p>
+
+<p><b>Livingstone, D.</b> 1857. Missionary travels and researches in South Africa.</p>
+
+<p><b>Lucas, H.</b> 1843. (note) <i>Latrodectus malmignatus</i> Bul. Soc. Ent., France,
+1843, p.&nbsp;viii.</p>
+
+<p><b>Ludlow, C.&nbsp;S.</b> 1914. Disease bearing mosquitoes of North and Central America,
+the West Indies and the Philippine Islands. War Dept., Office of Surgeon
+General. Bul. No.&nbsp;4, 1-96.</p>
+
+<p><b>Lugger</b>, 1896. Insects injurious in 1896. Agr. Exp. Sta. Bul.&nbsp;48. p.&nbsp;33to&nbsp;270.</p>
+
+<p><b>MacCallum, W.&nbsp;C.</b> 1898. On the hæmatozoan infection of birds. Journ.
+Exp. Med.&nbsp;iii, p.&nbsp;117.</p>
+
+<p><b>MacGregor, M.&nbsp;E.</b> 1914. The posterior stigmata of dipterous larvæ as a diagnostic
+character. Parasitology, vii, p.&nbsp;176-188.</p>
+
+<p><b>Macloskie, G.</b> 1888. The poison apparatus of the mosquito. Amer. Naturalist,
+xxii, p.&nbsp;884-888.</p>
+
+<p><b>Malloch, J.&nbsp;P.</b> 1913. American black-flies or Buffalo gnats. U.&nbsp;S. Dept.
+Agric. Bur. Ent. Tech. Bul.&nbsp;26, p.&nbsp;1-72.</p>
+
+<p>---- 1914. Notes on North American Diptera. Bul. Illinois State Lab.
+Nat. Hist., x, p.&nbsp;213-243.</p>
+
+<p><b>Manson, P.</b> 1911. Tropical diseases: a manual of the diseases of warm climates.
+8<sup>o</sup>. London, Cassell &amp;&nbsp;Co. (xx +&nbsp;876&nbsp;p.). 4&nbsp;ed. (1907). Reprinted.</p>
+
+<p><b>Marchoux, E.</b> and <b>Couvy, L.</b> 1913. Argas et spirochætes (1&nbsp;mémoire). Les
+granules de Leishman. Ann. Inst. Pasteur, xxvii, p.&nbsp;450-480. 2 mémoire.
+Le virus chez l'acarien. ibid. p.&nbsp;620-643.</p>
+
+<p><b>Marchoux, E.</b> and <b>Selimbeni, A.</b> 1903. La spirillose des poules. Ann. Inst.
+Pasteur, xvii, p.&nbsp;569-580.</p>
+
+<p><b>Marchoux, E.</b> and <b>Simond, P.&nbsp;L.</b> 1905. Études sur la fièvre jaune. Ann. Inst.
+Pasteur, xx, pp.&nbsp;16-40, 104-148, 161-205.</p>
+
+<p><b>Marlatt, C.&nbsp;L.</b> 1902. (See Howard, L.&nbsp;O. and Marlatt, C.&nbsp;L.)</p>
+
+<p>---- 1907. The bed-bug (<i>Cimex lectularius</i> L.) U.&nbsp;S. Dept. Agric., Bur.
+Ent., Circ. No.&nbsp;47, revised ed., 8&nbsp;pp.</p>
+
+<p><b>Martin, G.&nbsp;Leboeuf</b>, and <b>Roubaud</b>. 1909. Rapport de la mission d'études de la
+maladie du sommeil au Congo francais. 4<sup>o</sup>. Paris, Masson &amp;&nbsp;Cie. (vi&nbsp;+
+722&nbsp;p., 8&nbsp;pls. and map.).</p>
+
+<p><b>Maver, Maria&nbsp;B.</b> 1911. Transmission of spotted fever by other than Montana
+and Idaho ticks. Journ. Infec. Dis., viii, p.&nbsp;322-326.</p>
+
+<p><b>McClintic, T.&nbsp;B.</b> 1912. Investigations of and tick eradications in Rocky Mountain
+spotted fever. Publ. Health Repts., Washington, xxvii, p.&nbsp;732-760.</p>
+
+<p><b>Meckel, H.</b> 1847. Uber schwarzes Pigment in der Milz und im Blute einer
+Geisteskranken. Allgem. Zeitschr. f.&nbsp;Psychiatrie, iv, p.&nbsp;198-226.</p>
+
+<p><b>Megni, P.</b> 1906. Les insectes buveurs de sang. 12mo. Paris, Rudeval.
+(150&nbsp;p.).</p>
+
+<p><b>Melnikoff, N.</b> 1869. Ueber die Jugendzustände der <i>Tænia cucumerina</i>.
+Arch. f.&nbsp;Naturg., xxxv, p.&nbsp;62-70.</p>
+
+<p><b>Mense, C.</b> 1913. Handbuch der Tropenkrankheiten. 1&nbsp;Band. 4<sup>o</sup>. Leipzig,
+Barth (xv +&nbsp;295&nbsp;p.) Entomological parts by A.&nbsp;Eysell, and by Doerr and Russ.</p>
+
+<p><b>Minchin, E.&nbsp;A.</b> 1912. An introduction to the study of the Protozoa, with special
+reference to the parasitic forms. 8<sup>o</sup>. London. Arnold (xi&nbsp;+ 517&nbsp;p.).</p>
+
+<p><b>Mitchell, Evelyn&nbsp;G.</b> 1907. Mosquito life. 8vo. New York, Putmans.
+(xxii&nbsp;+ 281&nbsp;p.).</p>
+
+<p><b>Mitzmain, M.&nbsp;B.</b> 1910. General observations on the bionomics of the rodent
+and human flies. U.&nbsp;S. Publ. Health Service. Bul., 38, p.&nbsp;1-34.<span class="pagenum"><a name="Page_335" id="Page_335">[Pg 335]</a></span></p>
+
+<p>---- 1912. The rôle of <i>Stomoxys calcitrans</i> in the transmission of <i>Trypanosoma
+evansi</i>. Philippine Journ. Sci., vii, p.&nbsp;475-519, 5&nbsp;pls.</p>
+
+<p>---- 1913&nbsp;a. The biology of <i>Tabanus striatus</i> Fabricius, the horsefly of the
+Philippines. ibid., vii, B. p. 197-221.</p>
+
+<p>---- 1913&nbsp;b. The mechanical transmission of surra. ibid., viii, sec.&nbsp;B.,
+p.&nbsp;223-229.</p>
+
+<p>---- 1914&nbsp;a. Experimental insect transmission of anthrax. U.&nbsp;S. Public
+Health Repts. xxix, p.&nbsp;75-77.</p>
+
+<p>---- 1914&nbsp;b. I.&nbsp;Collected studies on the insect transmission of <i>Trypanosoma
+evansi</i>. II.&nbsp;Summary of experiments in the transmission of anthrax
+by biting flies. U.&nbsp;S. Pub. Health Service, Hyg. Lab. Bul., 94, p.&nbsp;1-48.</p>
+
+<p><b>Miyake, H.</b> and <b>Scriba, J.</b> 1893. Vorläufige Mitteilung über einen neuen
+Parasit des Menschen. Berl. klin. Wochenschr., xxx, p.&nbsp;374.</p>
+
+<p><b>Mollers, B.</b> 1907. Experimentelle Studien über die Uebertragung des Rückfallfiebers
+durch Zecken. Zeitschr. für Hyg. u.&nbsp;Infektionskrankheiten, lviii,
+p.&nbsp;277-286.</p>
+
+<p><b>Mote, D.&nbsp;C.</b> 1914. The cheese-skipper (<i>Piophila casei</i>). Ohio Naturalist xiv, p.&nbsp;309-310.</p>
+
+<p><b>Neiva, A.</b> 1910. Beiträge zur Biologie der <i>Conorhinus megistus</i> Burm. Memorias
+de Institute Oswaldo Cruz., ii, p.&nbsp;206-212.</p>
+
+<p><b>Neveu-Lemaire, M.</b> 1907. Un nouveau cas de parasitisme accidental d'un
+myriapode dans le tube digestif de l'homme, C.&nbsp;R. Soc. der Biol., lxiii
+p.&nbsp;305-308.</p>
+
+<p>---- 1908. Précis de parasitologie humaine. 8vo. Paris, Rudeval. (v&nbsp;+
+712&nbsp;p.).</p>
+
+<p><b>Newstead, R.</b> 1911. The papataci flies (Phlebotomus) of the Maltese Islands.
+Bul. of Ent. Research, ii, p.&nbsp;47-78, pls.&nbsp;1-3.</p>
+
+<p><b>Nicoll, W.</b> 1911. On the part played by flies in the disposal of the eggs of
+parasitic worms. Repts. to the Local Gov't. Board on Publ. Health and Med.
+Subjects, n.&nbsp;s. No.&nbsp;53, p.&nbsp;13-30.</p>
+
+<p><b>Nicolle, C.</b> 1910, Recherches expérimentales sur la typhus exanthématique
+entreprises à l'Institut Pasteur de Tunis pendant l'année 1909. Ann. Inst.
+Pasteur, xxiv, p.&nbsp;243-275.</p>
+
+<p>---- 1911. Recherches expérimentales sur la typhus exanthématique
+entreprises à l'Institut Pasteur de Tunis pendant l'année 1910. ibid., xxv,
+p.&nbsp;1-55, 97-154.</p>
+
+<p><b>Nicolle, C.</b>, <b>Blaizot, A.</b>, and <b>Conseil, E.</b> 1912&nbsp;a. Étiologie de la fièvre récurrente.
+Son mode de transmission par le pou. C.&nbsp;R. Acad. Sci., cliv, p.&nbsp;1636-1638.</p>
+
+<p>---- 1912&nbsp;b. Conditions de transmission de la fièvre récurrente par le pou.
+ibid., clv., p.&nbsp;481-484.</p>
+
+<p><b>Nicolle, C.</b> and <b>Catouillard, G.</b> 1905. Sur le venin d'un scorpion commun de
+Tunisie (<i>Heterometrus maurus</i>). C.&nbsp;R. Soc. Biol. lviii: p.&nbsp;100-102.</p>
+
+<p><b>Noe, G.</b> 1901. Sul ciclo evolutivo della <i>Filaria bancrofti</i> e&nbsp;delta <i>Filaria immitis</i>.
+Ricerche labr. anat. comp. norm. Univ. di Roma., viii, p.&nbsp;275-353.</p>
+
+<p><b>Norman, W.&nbsp;W.</b> 1896. The effect of the poison of centipedes. Trans. Texas
+Acad. Sci., i, p.&nbsp;118-119.</p>
+
+<p><b>Nuttall, G.&nbsp;H.&nbsp;F.</b> 1899. On the rôle of insects, arachnids, and myriapods as
+carriers in the spread of bacterial and parasitic diseases of man and animals.
+Johns Hopkins Hosp. Repts., viii, 154&nbsp;p., 3&nbsp;pls.</p>
+
+<p>---- 1908&nbsp;a. On the behavior of Spirochætæ in <i>Acanthia lectularia</i>. Parasitology,
+i, p.&nbsp;143-151.</p>
+
+<p>---- 1908&nbsp;b. The transmission of <i>Trypanosoma lewisi</i> by fleas and lice.
+ibid., i, p.&nbsp;296-301.</p>
+
+<p>---- 1908&nbsp;c. The Ixodoidea or ticks, spirochætosis in man and animals,
+piroplasmosis. Journ. Roy. Inst. Publ. Health, xvi, p.&nbsp;385-403, 449-464,
+513-526.</p>
+
+<p>---- 1914. Tick paralysis in man and animals. Parasitology, vii, p.&nbsp;95-104.<span class="pagenum"><a name="Page_336" id="Page_336">[Pg 336]</a></span></p>
+
+<p><b>Nuttall, G.&nbsp;H.&nbsp;F.</b> and <b>Jepson, F.&nbsp;P.</b> 1909. The part played by <i>Musca domestica</i>
+and allied (non-biting) flies in the spread of infective diseases. A summary
+of our present knowledge. Rept. to the Local Gov't Board on Publ. Health
+and Med. Subjects, n.&nbsp;s. 16, p.&nbsp;13-41.</p>
+
+<p><b>Nuttall, G.&nbsp;H.&nbsp;F.</b> and <b>Shipley, E.&nbsp;A.</b> 1901-03. Studies in relation to malaria.
+The structure and biology of Anopheles. Journ. Hyg., vols.&nbsp;i, ii, and iii.</p>
+
+<p><b>Orth, J.</b> 1910. Ueber die Beziehungungen der Haarsackmilbe zu Krebsbildungen
+in der Mamma. Berliner klin. Wochenschr., xlvii, p.&nbsp;452-453.</p>
+
+<p><b>Osborn, Herbert.</b> 1896. Insects affecting domestic animals. U. S. Dept.
+Agric., Bur. of Ent. Bul., 5, n.&nbsp;s., 302&nbsp;p.</p>
+
+<p>---- 1902. Poisonous insects. Article in Reference Handbook. Med. Sci.,
+v, p.&nbsp;158-169.</p>
+
+<p><b>Osler, W.</b> 1887. An address on the Hæmatozoa of malaria. British Med.
+Jour.&nbsp;i. p.&nbsp;556.</p>
+
+<p><b>Osten Sacken, C.&nbsp;R.</b> 1875-78, Prodrome of a Monograph of North American
+Tabanidæ. Mem. Boston Soc. Nat. Hist., ii, p.&nbsp;365-397, 421-479, and 555-566.</p>
+
+<p><b>Oudemans, A.&nbsp;C.</b> 1910. Neue Ansichten über die Morphologie des Flohkopfes,
+sowie über die Ontogenie, Phylogenie und Systematik der Flöhe. Novit.
+Zool., xvi, p.&nbsp;133-158.</p>
+
+<p><b>Patton, W.&nbsp;S.</b> 1907. Preliminary report on the development of the Leishman-Donovan
+body in the bed-bug. Sci. Mem., Med. and Sanitary Dept., Gov't
+of India, 28, p.&nbsp;1-19.</p>
+
+<p><b>Patton, W.&nbsp;S.</b> and <b>Cragg, F.&nbsp;W.</b> 1913. A textbook of medical entomology.
+4<sup>o</sup>. London, Christian Literature Society for India. (xxxiv&nbsp;+ 764&nbsp;p.)</p>
+
+<p><b>Pawlowsky, E.</b> 1906. Ueber den Steck- und Saug-apparat der Pediculiden.
+Zeitschr. wiss. Insektenbiol., ii, p.&nbsp;156-162, 198-204.</p>
+
+<p><b>Pawlowsky, E.</b> 1913. Scorpiotomische Mitteilungen. I.&nbsp;Ein Beitrag zur
+Morphologie des Giftdrüsen der Skorpione. Zeitschr. wiss. Zool., cv., p.&nbsp;157-177.
+Taf.&nbsp;x-xi.</p>
+
+<p><b>Pepper, W.</b>, <b>Schnauss, F. W.</b>, and <b>Smith, A. J.</b> 1908. Transient parasitism
+in men by a species of <i>Rhizoglyphus</i>. Univ. of Pa. Med. Bul.&nbsp;xxi, p.&nbsp;274-277.</p>
+
+<p><b>Petrovskaia, Maria.</b> 1910. Sur les myases produites chez l'homme par les
+Oestrides (Gastrophilus et Rhin&oelig;strus). Thèse, Fac. de médecine, Paris, 79&nbsp;p.</p>
+
+<p><b>Pettit, A.</b> and <b>Krohn, A.</b> 1905. Sur la structure des glandes salivaires du
+Notonecte (<i>Notonecta glauca</i>). Arch. anat. micr. Paris, vii, p.&nbsp;351-368,
+pl.&nbsp;13.</p>
+
+<p><b>Phisalix, Mme.</b> 1900. Un venin volatil. Sécrétion cutanée du <i>Iulus terrestris</i>.
+C.&nbsp;R. Soc. Biol. Paris, 1900, p.&nbsp;1033-1036.</p>
+
+<p>---- 1912. Effets physiologiques du venin de la Mygale de Haïti, le <i>Phormictopus
+cancerides</i> Pocock. Effets physiologiques du venin de la Mygale de
+Corse (<i>Cteniza sauvaga</i> Rossi); Bul. Mus. Paris, 1912: 134-138.</p>
+
+<p><b>Portschinsky, I.&nbsp;A.</b> 1908. <i>Rhin&oelig;strus purpureus</i>, a parasite of horses which
+deposits its larvæ in the eyes of man. Mss. transl. by Miss S.&nbsp;L. Weissman,
+in library of Ent. Dept., Cornell University.</p>
+
+<p>---- 1910. Biology of <i>Stomoxys calcitrans</i> and other coprophagous flies.
+Monograph in Russian. Mss. summarized transl. by Miss S.&nbsp;L. Weissman,
+in Library of Ent. Dept., C.&nbsp;U.</p>
+
+<p>---- 1911. <i>Gastrophilus intestinalis</i>. Mss. transl. by Miss S.&nbsp;L. Weissman,
+in library of Ent. Dept., C.&nbsp;U.</p>
+
+<p>---- 1913&nbsp;a. The sheep gad-fly, <i>Oestrus ovis</i>, its life, habits, methods of
+combating it, and its relation to man. Russian. Mss. summarized trans.
+by Miss S.&nbsp;L. Weissman, in library of Ent. Dept., C.&nbsp;U.</p>
+
+<p>---- 1913&nbsp;b. <i>Muscina stabulans</i>. A monograph in Russian. Mss., trans.
+by J.&nbsp;Millman, in library of Ent. Dept., Cornell Univ.</p>
+
+<p><b>Prowazek, S.</b> 1905. Studien über Säugetiertrypanosomen. Arb. aus dem
+kais. Gesundheitsamte&nbsp;xxii, p.&nbsp;351-395.</p>
+
+<p><b>Pusey, W.&nbsp;A.</b> 1911. The principles and practice of dermatology. 2&nbsp;ed, 8vo.
+Appleton &amp;&nbsp;Co. (1079&nbsp;p.)<span class="pagenum"><a name="Page_337" id="Page_337">[Pg 337]</a></span></p>
+
+<p><b>Rabinowitsch, L.</b> and <b>Kempner, W.</b> 1899. Beitrag zur Kentniss der Blutparasiten,
+speciell der Ratten trypanosomen. Zeitschr. f.&nbsp;Hyg. xxx, p.&nbsp;251-291.</p>
+
+<p><b>Ransom, B.&nbsp;H.</b> 1904. An account of the tape worms of the genus <i>Hymenolepis</i>
+parasitic in man. Bul. No.&nbsp;18, Hyg. Lab., U.&nbsp;S. Pub. Health and Mar.-Hosp.
+Serv., Wash., p.&nbsp;1-138.</p>
+
+<p>---- 1911. The life history of a parasitic nematode, <i>Hebronema muscæ</i>.
+Science n.&nbsp;s. xxxiv, p.&nbsp;690-692.</p>
+
+<p>---- 1913. The life history of <i>Habronema muscæ</i>, (Carter), a parasite of
+the horse transmitted by the house-fly. U.&nbsp;S. Dept. Agric. Bur. Animal,
+Ind. Bul.&nbsp;163, p.&nbsp;1-36.</p>
+
+<p><b>Reaumur, R.&nbsp;A.&nbsp;F. de.</b> 1738. Mémoires pour servir a l'histoirie des insectes.
+Histoire des cousins, iv, p.&nbsp;573-636.</p>
+
+<p><b>Reed, Walter.</b> 1900. The etiology of yellow fever. Philadelphia Med. Jour.
+Oct.&nbsp;27, 1900, vi, p.&nbsp;790-796.</p>
+
+<p><b>Reed, W.</b> and <b>Carroll, J.</b> 1901. The prevention of yellow fever. Med. Record,
+Oct.&nbsp;26, 1901, p.&nbsp;441-449.</p>
+
+<p><b>Reuter, Enzio.</b> 1910. Acari und Geschwulstätiologie. Centralbl. Bakt.
+Jena. Abt.&nbsp;1 lvi.; Originale 339-344.</p>
+
+<p><b>Reuter, O.&nbsp;M.</b> 1912. Bemerkungen über mein neues Heteropterensystem.
+Ofv. Finska Vetensk. Soc. Förh., liv. Afd.&nbsp;A. vi, p.&nbsp;1-62.</p>
+
+<p><b>Ribaga, C.</b> 1897. Sopra un organo particolare della Cimici dei letti (<i>Cimex
+lectularius</i>&nbsp;L.). Rivista di Patologia Vegetale, v, p.&nbsp;343-352.</p>
+
+<p><b>Ricardo, Gertrude.</b> 1900. Notes on the Pangoninæ. Ann. and Mag. Nat.
+Hist.&nbsp;v, p.&nbsp;97-121.</p>
+
+<p>---- 1901. Further Notes on the Pangoninæ. ibid. viii, p.&nbsp;286-315.</p>
+
+<p>---- 1904. Notes on the smaller genera of the Tabanidæ. ibid. xiv, p.&nbsp;349-373.</p>
+
+<p><b>Ricketts, H.&nbsp;T.</b> 1906-1910. Contributions to medical sciences by Howard
+Taylor Ricketts. 1870-1910. Univ. of Chicago Press. 1911.</p>
+
+<p>---- 1909. A microorganism which apparently has a specific relationship
+to Rocky Mountain spotted fever. A preliminary report. Jour. Amer.
+Med. Assoc. iii, p.&nbsp;373-380.</p>
+
+<p>---- Spotted fever reports&nbsp;1 and&nbsp;2. In the 4th Bien. Rept. State Board of
+Health, Montana, 1909, p.&nbsp;87-191.</p>
+
+<p><b>Ricketts, H.&nbsp;T.</b> and <b>Wilder, R.&nbsp;M.</b> 1910. The transmission of the typhus fever
+of Mexico (tabardillo) by means of the louse, <i>Pediculus vestimenti</i>. Journ.
+Am. Med. Assoc.&nbsp;liv. p.&nbsp;1304.</p>
+
+<p><b>Riley, C.&nbsp;V.</b> and <b>Howard, L.&nbsp;O.</b> 1889. A contribution to the literature of fatal
+spider-bites. Insect life, Washington, i. p.&nbsp;204-211.</p>
+
+<p><b>Riley, W.&nbsp;A.</b> 1906. A case of pseudoparasitism by dipterous larvæ. Canadian
+Ent. xxxviii, p.&nbsp;413.</p>
+
+<p>---- 1910&nbsp;a. Earlier references to the relation of flies to disease. Science
+n. s. xxxi, p.&nbsp;263-4.</p>
+
+<p>---- 1910&nbsp;b. <i>Dipylidium caninum</i> in an American child. Science n.&nbsp;s. xxxi,
+p.&nbsp;349-350.</p>
+
+<p>---- 1911. The relation of insects to disease. Cornell Countryman&nbsp;ix,
+p.&nbsp;51-55.</p>
+
+<p>---- 1912&nbsp;a. Notes on the relation of insects to disease. 8vo. Ithaca,
+N.&nbsp;Y. 51&nbsp;p.</p>
+
+<p>---- 1912&nbsp;b. Notes on animal parasites and parasitism. 8vo. Ithaca,
+N.&nbsp;Y. 55&nbsp;p.</p>
+
+<p>---- 1913. Some sources of laboratory material for work on the relations
+of insects to disease. Ent. News. xxiv, p.&nbsp;172-175.</p>
+
+<p>---- 1914. Mr. Nott's theory of insect causation of disease. Jour. of Parasitology.
+i, p.&nbsp;37-39.</p>
+
+<p><b>Rosenau, M.&nbsp;J.</b> and <b>Brues, C.&nbsp;T.</b> 1912. Some experimental observations on
+monkeys, concerning the transmission of poliomyelitis through the agency of
+<i>Stomoxys calcitrans</i>. Monthly Bul. Mass. State Board of Health. Vol.&nbsp;vii,
+p.&nbsp;314-317.<span class="pagenum"><a name="Page_338" id="Page_338">[Pg 338]</a></span></p>
+
+<p><b>Ross, R.</b> 1904. Researches on Malaria. The Nobel Medical Prize Lecture
+for 1902, Stockholm, Norstedt &amp;&nbsp;Söner. 89&nbsp;p. 9&nbsp;pls. In "Les Prix Nobel
+en 1902."</p>
+
+<p>---- 1910. The prevention of malaria. 4<sup>o</sup>. New York. Dutton &amp;&nbsp;Co.
+(xx&nbsp;+ 669&nbsp;p.).</p>
+
+<p><b>Rothschild, N.&nbsp;C.</b> 1905&nbsp;a. North American Ceratophyllus. Novitates Zoologicæ
+xii, p.&nbsp;153-174.</p>
+
+<p>---- 1905&nbsp;b. Some further notes on <i>Pulex canis</i> and <i>P.&nbsp;felis</i>. ibid. xii,
+p.&nbsp;192-193.</p>
+
+<p><b>Roubaud, E.</b> 1911. Les Choeromyies. C.&nbsp;R. Acad. Sci. Paris, cliii, p.&nbsp;553.</p>
+
+<p>---- 1913. Recherches sur les Auchméromyies. Bul. Sci. France et Belg.
+Paris, p.&nbsp;105-202.</p>
+
+<p><b>Sachs, Hans.</b> 1902. Zur Kentniss der Kreuzspinnengiftes. Beitr. Chem.
+hysiol.&nbsp;ii, p. 125-133. Abstr. Centralbl. Bakter. 1.&nbsp;Abth. xxxi., Referate,
+p.&nbsp;788.</p>
+
+<p><b>Sambon, L.&nbsp;W.</b> 1908. Report presented at the International Conference on
+Sleeping Sickness.</p>
+
+<p>---- 1910. Progress report on the investigation of pellagra. Reprinted
+from the Journ. Trop. Med. and Hyg.; London; Bale, Sons and Danielsson,
+12<sup>o</sup>. 125&nbsp;p.</p>
+
+<p><b>Sanderson, E.&nbsp;D.</b> 1910. Controlling the black-fly in the White Mountains.
+Jour. Econ. Ent.&nbsp;iii, p.&nbsp;27-29.</p>
+
+<p><b>Saul, E.</b> 1910. Untersuchungen über Beziehungen der Acari zur Geschwulstätiologie.
+Centralbl. Bakt. Jena, Abt.&nbsp;1, lv, Originale, p.&nbsp;15-18.</p>
+
+<p><b>Saul, E.</b> 1913. Beziehungen des Helminthen und Acari zur Geschwulstätiologie.
+ibid., Abt.&nbsp;1, lxxi, Originale, p.&nbsp;59-65.</p>
+
+<p><b>Sawyer, W. A.</b> and <b>Herms, W. B.</b> 1913. Attempts to transmit poliomyelitis
+by means of the stable-fly (<i>Stomoxys calcitrans</i>). Journ. Amer. Med. Assoc.
+lxi, p. 461-466.</p>
+
+<p><b>Schaudinn, F.</b> 1904. Generations- und Wirtwechsel bei <i>Trypanosoma</i> und
+Spirochæte. Arb. aus dem kais. Gesundheitsamte&nbsp;xx, p.&nbsp;387-493.</p>
+
+<p><b>Schiner, J.&nbsp;R.</b> 1862-64. Fauna Austriaca. Diptera, Vienna, I, lxxx +&nbsp;674;
+II, xxiii +&nbsp;658.</p>
+
+<p><b>Schnabl, J.</b> and <b>Dziedzicki, H.</b> 1911. Die Anthomyiden 4to. Halle. p.&nbsp;1-306.</p>
+
+<p><b>Schweinitz, G.&nbsp;E. de</b> and <b>Shumway, E.&nbsp;A.</b> 1904. Conjunctivitis nodosa, with
+histological examination. Univ. of Pa. Med. Bul., Nov. 1904.</p>
+
+<p><b>Sergent, E.</b> and <b>Foly, H.</b> 1910. Recherches sur la fièvre récurrente et son mode
+de transmission, dans une épidémie algérienne. Ann. Inst. Pasteur xxiv,
+p.&nbsp;337-373.</p>
+
+<p>---- 1911. Typhus récurrent Algérien. Sa transmission par les poux. Sa
+guérison par l'arsénobenzol. C.&nbsp;R. Soc. Biol. Paris. lxiii, p.&nbsp;1039-1040.</p>
+
+<p><b>Shipley, E.&nbsp;A.</b> 1914. Pseudo-parasitism. Parasitology, vi, p.&nbsp;351-352.</p>
+
+<p><b>Siler, J.&nbsp;F.</b>, <b>Garrison, P.&nbsp;E.,</b> and <b>MacNeal, W.&nbsp;J.</b> 1914. Further studies of the
+Thompson-McFadden Pellagra Commission. A summary of the second
+progress report. Journ. Amer. Med. Assoc. lxiii, p.&nbsp;1090-1093.</p>
+
+<p><b>Skelton, D&nbsp; S.</b> and <b>Parkham, J.&nbsp;G.</b> 1913. Leprosy and the bed-bug. R.&nbsp;A.&nbsp;M.&nbsp;C.
+Journ., xx, p.&nbsp;291.</p>
+
+<p><b>Skinner, H.</b> 1909. A remedy for the house-fleas. Journ. Econ. Ent.&nbsp;ii, p.&nbsp;192.</p>
+
+<p><b>Smith, G.&nbsp;U.</b> 1909. On some cases of relapsing fever in Egypt and the question
+of carriage by domestic vermin. Résumé in Ann. Inst. Pasteur xxiv, p.&nbsp;374-375.</p>
+
+<p><b>Smith, J.&nbsp;B.</b> 1904. Report upon the mosquitoes occurring within the State,
+their habits, life history, etc. N.&nbsp;J. Agric. Exp. Sta. 1904, p.&nbsp;1-482.</p>
+
+<p>---- 1908. The house mosquito, a city, town, and village problem. N.&nbsp;J.
+Agric. Exp. Sta. Bul. No.&nbsp;216, p.&nbsp;1-21.</p>
+
+<p><b>Smith, T.</b> and <b>Kilbourne, F.&nbsp;L.</b> 1893. Investigations into the nature, causation,
+and prevention of Texas or southern cattle fever. U.&nbsp;S. Dept. Agric.,
+Bur. Animal Ind. Bul.&nbsp;1, p.&nbsp;1-301. 10&nbsp;pls.</p>
+
+<p><b>Speiser, P.</b> 1903. Studien über Diptera pupipara. Zeitschr. Syst. Hymenopterologie
+und Dipt., iii, p,&nbsp;145-180.<span class="pagenum"><a name="Page_339" id="Page_339">[Pg 339]</a></span></p>
+
+<p><b>Spuler, A.</b> 1906. Ueber einen parasitisch lebenden Schmetterling, <i>Bradypodicola
+hahneli</i>. Biol. Centralbl., xxvi, p.&nbsp;690-697.</p>
+
+<p><b>Stiles, C.&nbsp;W.</b> 1905. A zoological investigation into the cause, transmission, and
+source of Rocky Mountain fever. U.&nbsp;S. Public Health and Marine Hosp.
+Serv. Hyg. Labr. Bul.&nbsp;14, 121&nbsp;p.</p>
+
+<p>---- 1907. Diseases caused by animal parasites. Osler's Modern Medicine,
+i, p.&nbsp;525-637.</p>
+
+<p>---- 1910&nbsp;a. The sanitary privy: its purpose and construction. Public
+Health Bul. No.&nbsp;37. U.&nbsp;S. Pub. Health and Marine Hosp. Service, p.&nbsp;1-24.</p>
+
+<p>---- 1910&nbsp;b. The taxonomic value of the microscopic structure of the stigmal
+plates in the tick genus <i>Dermacentor</i>. Bul. No.&nbsp;62; Hyg. Lab., U.&nbsp;S. Pub.
+Health and Mar. Hosp. Serc., Washington, p.&nbsp;1-72. 43&nbsp;pls.</p>
+
+<p><b>Stiles, C.&nbsp;W.</b> and <b>Gardner</b>. 1910. Further observations on the disposal of
+excreta. Public Health Repts. Washington. xxv, p.&nbsp;1825-1830.</p>
+
+<p><b>Stiles, C.&nbsp;W.</b> and <b>Keister, W.&nbsp;S.</b> 1913. Flies as carriers of Lamblia Spores.
+The contamination of food with human excreta. Public Health Repts.
+Washington, xxviii, p.&nbsp;2530-2534.</p>
+
+<p><b>Stiles, C.&nbsp;W.</b> and <b>Lumsden, L.&nbsp;L.</b> 1911. The sanitary privy. U.&nbsp;S. Dept.
+Agric., Farmers Bul.&nbsp;463, 32&nbsp;p.</p>
+
+<p><b>Strickland, C.</b> 1914. The biology of <i>Ceratophyllus fasciatus</i> Bosc., the common
+rat-flea of Great Britain. Jour. Hygiene, xiv, p.&nbsp;139-142.</p>
+
+<p><b>Strong, R.&nbsp;P.</b> and <b>Teague, O.</b> 1912. Infectivity of the breath. Rept. of
+Intern. Plague Conf. held at Mukden, Apr. 1911, p.&nbsp;83-87.</p>
+
+<p><b>Strong, R.&nbsp;P.</b>, <b>Tyzzer, E.&nbsp;E.</b>, and <b>Brues, C.&nbsp;T.</b> 1913. Verruga peruviana,
+Oroya fever and uta. Journ. Amer. Med. Assoc.&nbsp;lxi, p.&nbsp;1713-1716.</p>
+
+<p><b>Stryke, Anna&nbsp;C.</b> 1912. The life-cycle of the malarial parasite. Entom. News.
+xxiii, p.&nbsp;221-223.</p>
+
+<p><b>Surcouf, J.</b> 1913. La transmission du ver macaque par un moustique. C.&nbsp;R.
+Acad. Sci., Paris, clvi, p.&nbsp;1406-1408.</p>
+
+<p><b>Taschenberg, O.</b> 1909. Die giftigen Tiere. 8vo. Stuttgart, Enke. (xv&nbsp;+
+325&nbsp;p.).</p>
+
+<p><b>Taute, M.</b> 1911. Experimentelle Studien über die Beziehungen der <i>Glossina
+morsitans</i> zur Schlafkrankheit. Zeitschr. f.&nbsp;Hyg. lxix, p.&nbsp;553-558.</p>
+
+<p><b>Temple, I.&nbsp;U.</b> 1912. Acute ascending paralysis, or tick paralysis. Medical
+Sentinel, Portland, Oregon. Sept. 1912. (Reprint unpaged.)</p>
+
+<p><b>Theobald, F.&nbsp;V.</b> 1901+ A monograph of the Culicidæ of the World. Five
+volumes. London.</p>
+
+<p><b>Thebault, V.</b> 1901. Hémorrhagie intestinale et affection typhiode causée par
+des larves de Diptère. Arch. Parasit.&nbsp;iv, p.&nbsp;353-361</p>
+
+<p><b>Thompson, D.</b> 1913. Preliminary note on bed-bugs and leprosy. British
+Med. Journ. 1913, p.&nbsp;847.</p>
+
+<p><b>Tiraboschi, C.</b> 1904. Les rats, les souris et leurs parasites cutanés dans leurs
+rapports avec la propagation de la peste bubonique. Arch. Parasit. viii,
+p.&nbsp;161-349.</p>
+
+<p><b>Topsent, E.</b> 1901. Sur un cas de myase hypodermique chez l'homme. Arch.
+Parasit., iv. p.&nbsp;607-614.</p>
+
+<p><b>Torrey, J.&nbsp;C.</b> 1912. Numbers and types of bacteria carried by city flies.
+Journ. of Inf. Dis., x, p.&nbsp;166-177.</p>
+
+<p><b>Townsend, C.&nbsp;H.&nbsp;T.</b> 1908. The taxonomy of the Muscoidean flies. Smithsonian
+Misc. Col., p.&nbsp;1-138.</p>
+
+<p>---- 1911. Review of work by Pantel and Portchinski on reproductive and
+early stage characters of Muscoid flies. Proc. Ent. Soc., Washington, xiii,
+p.&nbsp;151-170.</p>
+
+<p>---- 1912. Muscoid names. ibid., xiv, p.&nbsp;45.</p>
+
+<p>---- 1913&nbsp;a. Preliminary characterization of the vector of verruga, <i>Phlebotomus
+verrucarum</i> sp. nov. Insecutor Inscitiæ Menstruus, Washington, i,
+p.&nbsp;107-109.</p>
+
+<p>---- 1913&nbsp;b. The transmission of verruga by <i>Phlebotomus</i>. Journ. Amer.
+Med. Assoc., lxi, p.&nbsp;1717.<span class="pagenum"><a name="Page_340" id="Page_340">[Pg 340]</a></span></p>
+
+<p>---- 1914&nbsp;a. The relations between lizards and <i>Phlebotomus verrucarum</i>
+as indicating the reservoir of verruga. Science n.&nbsp;s., xl, p.&nbsp;212-214.</p>
+
+<p>---- 1914&nbsp;b. Progress of verruga work with <i>Phlebotomus verrucarum</i>&nbsp;T.
+Journ. Econ. Ent., vii. p.&nbsp;357-367.</p>
+
+<p><b>Trouessart, E.</b> 1902. Endoparasitisme accidental chez l'homme d'une espèce
+de Sarcoptidæ détriticole, (<i>Histiogaster spermaticus</i>). Arch. Parasit., v,
+p.&nbsp;449-459.</p>
+
+<p><b>Tsunoda, T.</b> 1910. Eine Milbenart von <i>Glyciphagus</i> als Endoparasit. D.
+med. Wochenschr., xxxvi, p.&nbsp;1327-1328.</p>
+
+<p><b>Tyzzer, E.&nbsp;E.</b> 1907. The pathology of the brown-tail moth dermatitis. In
+2d Rept. of the Supt. for Suppressing the Gypsy and Brown-tail Moths,
+Boston, 1907, p.&nbsp;154-168.</p>
+
+<p><b>Vaughan</b>,</p>
+
+<p><b>Verdun, P.</b> and <b>Bruyant, L.</b> 1912. Un nouveau cas de pseudo-parasitisme d'un
+myriapode, (<i>Chætachlyne vesuviana</i>) chez l'homme. C.&nbsp;R. Soc. Biol.,
+Paris, lxiv, p.&nbsp;236-237.</p>
+
+<p><b>Verjbitski, D.&nbsp;T.</b> The part played by insects in the epidemiology of plague.
+Transl. from Russian in Jour. Hyg., viii, p.&nbsp;162-208.</p>
+
+<p><b>Villeneuve, J.</b> 1914. Quelques réflexions au sujet de la tribu des Calliphorinæ
+Bul. Soc. Ent., France, No.&nbsp;8, p.&nbsp;256-258.</p>
+
+<p><b>Ward, H.&nbsp;B.</b> 1905. The relation of animals to disease. Science n.&nbsp;s. xxii,
+p.&nbsp;193-203.</p>
+
+<p><b>Watson, J.&nbsp;J.</b> 1910. Symptomology of pellagra and report of cases. Trans.
+Nat. Conference on Pellagra, Columbia, S.&nbsp;C., Nov.&nbsp;3 and&nbsp;4, 1909, p.&nbsp;207-218.</p>
+
+<p><b>Weed, C.&nbsp;M.</b> 1904. An experiment with black-flies. U.&nbsp;S. Dept. Agric., Bur.
+Ent. Bul. n.&nbsp;s., 46, p.&nbsp;108-109.</p>
+
+<p><b>Wellman, F.&nbsp;C.</b> 1906. Human trypanosomiasis and spirochætosis in Portuguese
+Southwest Africa, with suggestions for preventing their spread in the
+Colony. Journ. Hyg., vi, p.&nbsp;237-345.</p>
+
+<p><b>Werner, F.</b> 1911. Scorpions and allied annulated spiders. Wellcome Trop.
+Research Laboratories, 4th Rept., vol.&nbsp;B, p.&nbsp;178-194. Pls.&nbsp;xiv-xv.</p>
+
+<p><b>Whitfield, A.</b> 1912. A method of rapidly exterminating pediculi capitis.
+Lancet 1912 (2), p. 1648. See notes.</p>
+
+<p><b>Williston, S.&nbsp;W.</b> 1908. Manual of the North American Diptera, New Haven,
+p.&nbsp;1-405.</p>
+
+<p><b>Wilson, G.&nbsp;B.</b> and <b>Chowning, W.&nbsp;M.</b> 1903. Studies in <i>Piroplasmosis hominis</i>.
+Journ. Inf. Dis., iv, p.&nbsp;31-57.</p>
+
+<p><b>Wilson, W.&nbsp;H.</b> 1904. On the venom of scorpions. Rec. Egyptian Gov't
+School of Medicine, Cairo, ii, p.&nbsp;7-44.</p></div><p><span class="pagenum"><a name="Page_341" id="Page_341">[Pg 341]</a></span></p>
+
+
+
+<hr style="width: 65%;" />
+<h2><a name="INDEX" id="INDEX"></a>INDEX</h2>
+
+
+<pre>
+Abscess, <a href="#Page_178">178</a>
+
+Acanthia, <a href="#Page_87">87</a>
+
+Acariasis, <a href="#Page_58">58</a>
+
+Acarina, <a href="#Page_23">23</a>, <a href="#Page_58">58</a>, <a href="#Page_131">131</a>, <a href="#Page_259">259</a>
+
+Acarus dysenteriæ, <a href="#Page_132">132</a>
+
+Accidental parasites, <a href="#Page_131">131</a>, <a href="#Page_132">132</a>, <a href="#Page_134">134</a>
+
+Aedes, <a href="#Page_194">194</a>, <a href="#Page_293">293</a>
+
+Aedes calopus, <a href="#Page_182">182</a>, <a href="#Page_201">201</a>, <a href="#Page_205">205</a>, <a href="#Page_206">206</a>, <a href="#Page_208">208</a>
+
+Aedes cantator, <a href="#Page_101">101</a>
+
+Aedes sollicitans, <a href="#Page_101">101</a>
+
+Aedes tæniorhynchus, <a href="#Page_101">101</a>
+
+Aerobic bacteria, <a href="#Page_152">152</a>
+
+Æstivo-autumnal, <a href="#Page_186">186</a>
+
+African Relapsing Fever, <a href="#Page_230">230</a>
+
+Akis spinosa, <a href="#Page_177">177</a>
+
+Alternation of Generations, <a href="#Page_175">175</a>
+
+Amblyomma, <a href="#Page_264">264</a>
+
+Amblyomma americanum, <a href="#Page_67">67</a>
+
+Amblyomma cajennense, <a href="#Page_67">67</a>
+
+American dog tick, <a href="#Page_228">228</a>
+
+Am&oelig;boid organism, <a href="#Page_189">189</a>
+
+Anisolabis annulipes, <a href="#Page_177">177</a>
+
+Anterior poliomyelitis, <a href="#Page_241">241</a>
+
+Anopheles, <a href="#Page_194">194</a>, <a href="#Page_291">291</a>
+
+Anopheles crucians, <a href="#Page_199">199</a>
+
+Anopheles maculipennis, <a href="#Page_182">182</a>
+
+Anopheles punctipennis, <a href="#Page_198">198</a>
+
+Anopheles quadrimaculatus, <a href="#Page_197">197</a>
+
+Anopheline, <a href="#Page_192">192</a>
+
+Anthocoris, <a href="#Page_279">279</a>
+
+Anthomyiidæ, <a href="#Page_300">300</a>
+
+Anthomyia, <a href="#Page_138">138</a>
+
+Anthrax, <a href="#Page_165">165</a>
+
+Antipruritic treatment, <a href="#Page_72">72</a>
+
+Ants, <a href="#Page_42">42</a>
+
+Aphiochæta, <a href="#Page_295">295</a>
+
+Apis mellifica, <a href="#Page_36">36</a>
+
+Arachnida, <a href="#Page_258">258</a>
+
+Araneida, <a href="#Page_6">6</a>
+
+Argas, <a href="#Page_64">64</a>
+
+Argas persicus, <a href="#Page_63">63</a>, <a href="#Page_235">235</a>, <a href="#Page_237">237</a>
+
+Argasidæ, <a href="#Page_62">62</a>
+
+Argopsylla, <a href="#Page_317">317</a>
+
+Argus, <a href="#Page_259">259</a>
+
+Arilus, <a href="#Page_284">284</a>
+
+Arthropods, poisonous, <a href="#Page_6">6</a>
+
+Asopia farinalis, <a href="#Page_177">177</a>
+
+Assassin-bugs, <a href="#Page_31">31</a>, <a href="#Page_219">219</a>
+
+Auchmeromyia, <a href="#Page_117">117</a>
+
+Automeris io, <a href="#Page_47">47</a>
+
+Avicularoidea, <a href="#Page_12">12</a>
+
+
+Babesia, <a href="#Page_226">226</a>
+
+Babesia bovis, <a href="#Page_223">223</a>
+
+Babesia ovis, <a href="#Page_225">225</a>
+
+Babesiosis, <a href="#Page_221">221-222</a>
+
+Bacilli, <a href="#Page_170">170</a>
+
+Bacillus icteroides, <a href="#Page_202">202</a>, <a href="#Page_205">205</a>
+
+Bacillus pestis, <a href="#Page_166">166</a>
+
+Bacillus typhosus, <a href="#Page_153">153</a>
+
+Back swimmers, <a href="#Page_30">30</a>
+
+Bdellolarynx, <a href="#Page_304">304</a>
+
+Beauperthuy, Louis Daniel, <a href="#Page_2">2</a>
+
+Bed-bug, <a href="#Page_86">86</a>, <a href="#Page_88">88</a>, <a href="#Page_90">90</a>, <a href="#Page_173">173</a>, <a href="#Page_219">219-220</a>
+
+Bed-bug, cone-nosed, <a href="#Page_92">92</a>
+
+Blister beetles, <a href="#Page_54">54</a>
+
+Belostoma, <a href="#Page_28">28</a>, <a href="#Page_277">277</a>
+
+Belostoma americana, <a href="#Page_31">31</a>
+
+Belostomatidæ, <a href="#Page_30">30</a>
+
+Bengalia, <a href="#Page_314">314</a>
+
+Bird-spiders, <a href="#Page_10">10</a>
+
+Black death, <a href="#Page_1">1</a>, <a href="#Page_166">166</a>
+
+Black flies, <a href="#Page_33">33</a>, <a href="#Page_104">104</a>, <a href="#Page_247">247</a>
+
+Black heads, <a href="#Page_80">80</a>
+
+Blaps mortisaga, <a href="#Page_134">134</a>
+
+Blepharoceridæ, <a href="#Page_286">286</a>
+
+Boophilus, <a href="#Page_264">264</a>
+
+Boophilus annulatus, <a href="#Page_67">67</a>, <a href="#Page_223">223-225</a>
+
+Bot-flies, <a href="#Page_112">112</a>
+
+Blue bottle flies, <a href="#Page_140">140</a>
+
+Brill's disease, <a href="#Page_238">238</a>
+
+Brown-tailed moth, <a href="#Page_48">48</a>
+
+Bruck, <a href="#Page_34">34</a>
+
+Buthus quinquestriatus, <a href="#Page_21">21</a>
+
+
+Cabbage butterfly, <a href="#Page_56">56</a>
+
+Calliphora, <a href="#Page_136">136</a>, <a href="#Page_140">140</a>, <a href="#Page_312">312</a>
+
+Calliphora erythrocephala, <a href="#Page_141">141</a><span class="pagenum"><a name="Page_342" id="Page_342">[Pg 342]</a></span>
+
+Calobata, <a href="#Page_296">296</a>
+
+Camponotinæ, <a href="#Page_43">43</a>
+
+Cancer, <a href="#Page_254">254</a>
+
+Cantharidin, <a href="#Page_54">54</a>
+
+Cantharidin poison, <a href="#Page_55">55</a>
+
+Canthariasis, <a href="#Page_134">134</a>
+
+Capsidæ, <a href="#Page_280">280</a>
+
+Carriers, simple, <a href="#Page_4">4</a>, <a href="#Page_144">144</a>
+
+Carriers of disease, <a href="#Page_144">144</a>
+
+Carrion's fever, <a href="#Page_253">253</a>
+
+Caterpillar rash, <a href="#Page_45">45</a>
+
+Cat flea, <a href="#Page_172">172</a>
+
+Cattle ticks, <a href="#Page_222">222</a>
+
+Causative organism, <a href="#Page_170">170</a>
+
+Cellia, <a href="#Page_291">291</a>
+
+Centipedes, <a href="#Page_25">25</a>, <a href="#Page_257">257</a>
+
+Ceratophyllus, <a href="#Page_120">120</a>, <a href="#Page_316">316</a>
+
+Ceratophyllus acutus, <a href="#Page_123">123</a>
+
+Ceratophyllus fasciatus, <a href="#Page_122">122</a>, <a href="#Page_172">172</a>, <a href="#Page_213">213</a>
+
+Ceratopogon, <a href="#Page_108">108</a>
+
+Cheese-fly, <a href="#Page_137">137</a>
+
+Cheyletus eruditus, <a href="#Page_271">271</a>
+
+Chigger, <a href="#Page_60">60</a>, <a href="#Page_70">70</a>
+
+Chigoes, <a href="#Page_126">126</a>
+
+Chilopoda, <a href="#Page_25">25</a>, <a href="#Page_257">257</a>
+
+Chiracanthium nutrix, <a href="#Page_18">18</a>
+
+Chironomidæ, <a href="#Page_107">107</a>
+
+Chorioptes, <a href="#Pg_270">270</a>
+
+Chrysomelid, <a href="#Page_55">55</a>
+
+Chrysomyia, <a href="#Page_136">136</a>, <a href="#Page_308">308</a>
+
+Chrysomyia macellaria, <a href="#Page_117">117</a>, <a href="#Page_140">140</a>
+
+Chrysops, <a href="#Page_294">294</a>
+
+Chylous dropsy, <a href="#Page_179">179</a>
+
+Chyluria, <a href="#Page_178">178</a>
+
+Cicadidæ, <a href="#Page_55">55</a>
+
+Cimex L., <a href="#Page_278">278</a>
+
+Cimex boueti, <a href="#Page_92">92</a>
+
+Cimex columbarius, <a href="#Page_92">92</a>
+
+Cimex hemipterus, <a href="#Page_91">91</a>, <a href="#Page_220">220</a>
+
+Cimex hirundinis, <a href="#Page_92">92</a>
+
+Cimex inodorus, <a href="#Page_92">92</a>
+
+Cimex lectularius, <a href="#Page_87">87</a>, <a href="#Page_219">219</a>
+
+Citheronia regalis, <a href="#Page_44">44</a>
+
+Clinocoris, <a href="#Page_87">87</a>
+
+Coleoptera, <a href="#Page_134">134</a>, <a href="#Page_274">274</a>
+
+Comedons, <a href="#Page_80">80</a>
+
+Complete metamorphosis, <a href="#Page_80">80</a>
+
+Compressor muscle, <a href="#Page_20">20</a>
+
+Compsomyia, <a href="#Page_117">117</a>
+
+Cone-nosed bed-bug, <a href="#Page_92">92</a>
+
+Conjunctivitis, nodular, <a href="#Page_52">52</a>
+
+Conorhinus, <a href="#Page_282">282</a>
+
+Conorhinus megistus, <a href="#Page_93">93</a>, <a href="#Page_219">219-220</a>
+
+Conorhinus rubrofasciatus, <a href="#Page_220">220</a>
+
+Conorhinus sanguisugus, <a href="#Page_32">32</a>, <a href="#Page_92">92</a>
+
+Copra itch, <a href="#Page_72">72</a>
+
+Cordylobia, <a href="#Page_118">118</a>
+
+Coriscus, <a href="#Page_280">280</a>
+
+Coriscus subcoleoptratus, <a href="#Page_32">32</a>
+
+Creeping myasis, <a href="#Page_112">112</a>
+
+Crustacea, <a href="#Page_257">257</a>
+
+Cryptocystis, <a href="#Page_176">176</a>
+
+Cryptotoxic, <a href="#Page_54">54-55</a>
+
+Cteniza sauvagei, <a href="#Page_13">13</a>
+
+Ctenocephalus, <a href="#Page_120">120</a>, <a href="#Page_172">172</a>, <a href="#Page_213">213</a>, <a href="#Page_317">317</a>
+
+Culex, <a href="#Page_194">194</a>, <a href="#Page_201">201</a>, <a href="#Page_293">293</a>
+
+Culex pipiens, <a href="#Page_35">35</a>, <a href="#Page_98">98</a>
+
+Culex quinquefasciatus, <a href="#Page_180">180</a>
+
+Culex sollicitans, <a href="#Page_200">200</a>
+
+Culex territans, <a href="#Page_101">101</a>
+
+Culicidæ, <a href="#Page_33">33</a>, <a href="#Page_97">97</a>
+
+Culicin, <a href="#Page_34">34</a>
+
+Culicoides, <a href="#Page_109">109</a>, <a href="#Page_288">288</a>
+
+Cyclops, <a href="#Page_183">183</a>, <a href="#Page_257">257</a>
+
+Cynomyia, <a href="#Page_136">136</a>, <a href="#Page_311">311</a>
+
+
+Dance, St. Vitus, <a href="#Page_8">8</a>
+
+Dancing mania, <a href="#Page_8">8</a>
+
+Deer-flies, <a href="#Page_110">110</a>
+
+Definitive host, <a href="#Page_192">192</a>
+
+Demodecidæ, <a href="#Page_78">78</a>
+
+Demodex, <a href="#Page_259">259</a>
+
+Demodex folliculorum, <a href="#Page_78">78</a>
+
+Dermacentor, <a href="#Page_262">262</a>
+
+Dermacentor andersoni, <a href="#Page_67">67</a>, <a href="#Page_228">228</a>
+
+Dermacentor occidentalis, <a href="#Page_227">227</a>
+
+Dermacentor variabilis, <a href="#Page_67">67</a>
+
+Dermacentor venustus, <a href="#Page_24">24</a>, <a href="#Page_228">228</a>
+
+Dermanyssidæ, <a href="#Page_68">68</a>
+
+Dermanyssus, <a href="#Pg_266">266</a>
+
+Dermanyssus gallinæ, <a href="#Page_68">68</a>
+
+Dermatitis, <a href="#Page_72">72</a>, <a href="#Page_77">77</a>, <a href="#Page_85">85</a>
+
+Dermatobia, <a href="#Page_115">115</a>, <a href="#Page_298">298</a>
+
+Dermatobia cyaniventris, <a href="#Page_163">163</a>
+
+Dermatophilus, <a href="#Page_317">317</a>
+
+Dermatophilus penetrans, <a href="#Page_60">60</a>, <a href="#Page_126">126</a><span class="pagenum"><a name="Page_343" id="Page_343">[Pg 343]</a></span>
+
+Diamphidia simplex, <a href="#Page_55">55</a>
+
+Dimorphism, <a href="#Page_65">65</a>
+
+Direct inoculators, <a href="#Page_4">4</a>
+
+Diplopoda, <a href="#Page_25">25</a>, <a href="#Page_257">257</a>
+
+Diptera, <a href="#Page_33">33</a>, <a href="#Page_94">94</a>, <a href="#Page_274">274</a>
+
+Dipterous Larvæ, <a href="#Page_135">135</a>
+
+Dipylidium, <a href="#Page_175">175</a>, <a href="#Page_221">221</a>
+
+Dipylidium caninum, <a href="#Page_4">4</a>, <a href="#Page_175">175-176</a>
+
+Dog flea, <a href="#Page_172">172</a>
+
+Dracunculus, <a href="#Page_257">257</a>
+
+Dracunculus medinensis, <a href="#Page_182">182</a>
+
+Drosophila, <a href="#Page_296">296</a>
+
+Dum-dum fever, <a href="#Page_220">220</a>
+
+Dysentery, <a href="#Page_154">154</a>
+
+
+Ear-flies, <a href="#Page_110">110</a>
+
+Earwig, <a href="#Page_177">177</a>
+
+Echidnophaga, <a href="#Page_317">317</a>
+
+Echinorhynchus, <a href="#Page_185">185</a>
+
+Elephantiasis, <a href="#Page_178">178-179</a>
+
+Empoasca mali, <a href="#Page_33">33</a>
+
+Empretia, <a href="#Page_46">46</a>
+
+English Plague Commission, <a href="#Page_171">171</a>
+
+Epeira diadema, <a href="#Page_18">18</a>
+
+Epizootic, <a href="#Page_170">170</a>
+
+Eristalis, <a href="#Page_137">137</a>, <a href="#Page_295">295</a>
+
+Essential hosts, <a href="#Page_4">4</a>, <a href="#Page_165">165</a>
+
+Eumusca, <a href="#Page_307">307</a>
+
+European Relapsing Fever, <a href="#Page_233">233</a>
+
+Euproctis chrysorrh&oelig;a, <a href="#Page_48">48</a>
+
+Eusimulium, <a href="#Page_286">286</a>
+
+
+Facultative parasites, <a href="#Page_131">131</a>
+
+Fannia, <a href="#Page_136">136</a>, <a href="#Page_138">138</a>, <a href="#Page_145">145</a>, <a href="#Page_300">300</a>
+
+Federal Health Service, <a href="#Page_169">169</a>
+
+Fever, lenticular, <a href="#Page_237">237</a>
+  African Relapsing, <a href="#Page_230">230</a>, <a href="#Page_234">234</a>
+  Carrion's, <a href="#Page_253">253</a>
+  dum-dum, <a href="#Page_154">154</a>
+  European Relapsing, <a href="#Page_233">233</a>
+  pappatici, <a href="#Page_96">96</a>
+  red water, <a href="#Page_220">220</a>
+  Rocky Mt. Spotted, <a href="#Page_226">226</a>
+  three day, <a href="#Page_96">96</a>
+  Typhus, <a href="#Page_237">237</a>
+
+Filaria, <a href="#Page_178">178</a>, <a href="#Page_221">221</a>
+  immitis, <a href="#Page_182">182</a>
+
+Filariasis, <a href="#Page_178">178</a>
+
+Flannel-moth larvæ, <a href="#Page_44">44</a>
+
+Fleas, <a href="#Page_119">119</a>, <a href="#Page_166">166</a>, <a href="#Page_213">213</a>
+  cat, <a href="#Page_172">172</a>
+  dog, <a href="#Page_172">172</a>
+  human, <a href="#Page_172">172</a>, <a href="#Page_176">176</a>
+  rodent, <a href="#Page_123">123</a>, <a href="#Page_172">172</a>
+  rat, <a href="#Page_171">171</a>
+
+Flesope, <a href="#Page_125">125</a>
+
+Formaldehyde, <a href="#Page_91">91</a>
+
+Fomites, <a href="#Page_199">199</a>, <a href="#Page_204">204</a>
+
+Fulgoridæ, <a href="#Page_28">28</a>
+
+Fumigation, <a href="#Page_320">320</a>
+
+
+Gamasid, <a href="#Page_68">68</a>
+
+Gangrene, <a href="#Page_129">129</a>
+
+Gastrophilus, <a href="#Page_113">113</a>, <a href="#Page_297">297</a>
+
+Giant crab spiders, <a href="#Page_13">13</a>
+
+Giant water bugs, <a href="#Page_30">30</a>
+
+Gigantorhynchus, <a href="#Page_185">185</a>
+
+Glossina, <a href="#Page_117">117</a>, <a href="#Page_297">297</a>, <a href="#Page_303">303</a>
+
+Glossina morsitans, <a href="#Page_214">214</a>, <a href="#Page_217">217</a>
+  palpalis, <a href="#Page_215">215</a>, <a href="#Page_217">217</a>, <a href="#Page_218">218</a>
+
+Glyciphagus, <a href="#Page_267">267</a>
+
+Grain moth, <a href="#Page_69">69</a>
+
+Grocer's itch, <a href="#Page_72">72</a>
+
+Guinea-worm, <a href="#Page_182">182</a>
+
+
+Habronema muscæ, <a href="#Page_156">156</a>, <a href="#Page_183">183</a>
+
+Hæmatobia, <a href="#Page_166">166</a>, <a href="#Page_304">304</a>
+  irritans, <a href="#Page_146">146</a>
+
+Hæmatobosca, <a href="#Page_304">304</a>
+
+Hæmatomyidium, <a href="#Page_288">288</a>
+
+Hæmatopinus spinulosus, <a href="#Page_213">213</a>
+
+Hæmatopota, <a href="#Page_294">294</a>
+
+Hæmatosiphon, <a href="#Page_279">279</a>
+
+Hæmoglobinuria, <a href="#Page_222">222</a>
+
+Hæmozoin, <a href="#Page_189">189</a>
+
+Harpactor, <a href="#Page_284">284</a>
+
+Harvest mites, <a href="#Page_60">60</a>
+  effect of, <a href="#Page_59">59</a>
+
+Head-louse, <a href="#Page_173">173</a>
+
+Helminthiasis, <a href="#Page_138">138</a>
+
+Helophilus, <a href="#Page_295">295</a>
+
+Hemiptera, <a href="#Page_27">27</a>, <a href="#Page_86">86</a>, <a href="#Page_273">273-275</a>
+
+Heteropodidæ, <a href="#Page_13">13</a>
+
+Heuchis sanguinea, <a href="#Page_55">55</a>
+
+Hexapod larvæ, <a href="#Page_58">58</a>
+
+Hexapoda, <a href="#Page_27">27</a>, <a href="#Page_80">80</a>, <a href="#Page_258">258</a><span class="pagenum"><a name="Page_344" id="Page_344">[Pg 344]</a></span>
+
+Hippelates, <a href="#Page_297">297</a>
+
+Hippobosca, <a href="#Page_285">285</a>
+
+Histiogaster, <a href="#Page_269">269</a>
+  spermaticus, <a href="#Page_132">132</a>
+
+Homalomyia, <a href="#Page_136">136</a>, <a href="#Page_138">138</a>, <a href="#Page_300">300</a>
+
+Honey bee, <a href="#Page_36">36</a>
+  poison of, <a href="#Page_37">37</a>
+
+Hornets, <a href="#Page_43">43</a>
+
+Horn-fly, <a href="#Page_137">137</a>, <a href="#Page_304">304</a>, <a href="#Page_308">308</a>
+
+Horse-fly, <a href="#Page_110">110</a>, <a href="#Page_165">165</a>
+
+House-fly, <a href="#Page_137">137-139</a>, <a href="#Page_144">144</a>, <a href="#Page_183">183</a>
+  control of, <a href="#Page_156">156</a>, <a href="#Page_160">160</a>
+
+Human flea, <a href="#Page_124">124</a>
+
+Host, definitive, <a href="#Page_175">175</a>
+  intermediate, <a href="#Page_175">175</a>
+  primary, <a href="#Page_175">175</a>
+
+Hyalomma, <a href="#Page_264">264</a>
+  ægypticum, <a href="#Page_224">224-225</a>
+
+Hydrocyanic Acid Gas, <a href="#Page_318">318</a>
+
+Hydrotæa, <a href="#Page_300">300</a>
+
+Hymenolepis diminuta, <a href="#Page_176">176</a>
+
+Hymenoptera, <a href="#Page_36">36</a>, <a href="#Page_275">275</a>
+
+Hypoderma, <a href="#Page_113">113</a>, <a href="#Page_298">298</a>
+  diana, <a href="#Page_113">113</a>
+  lineata, <a href="#Page_113">113</a>
+
+Hypopharynx, <a href="#Page_80">80</a>
+
+
+Immunity from stings, <a href="#Page_39">39</a>
+
+Incomplete metamorphosis, <a href="#Page_80">80</a>
+
+Infantile paralysis, <a href="#Page_162">162</a>, <a href="#Page_241">241</a>
+  splenic, <a href="#Page_220">220</a>
+  Direct inoculation, <a href="#Page_164">164</a>
+
+Insects, <a href="#Page_258">258</a>
+  blood-sucking, <a href="#Page_170">170</a>
+
+Intermediate host, <a href="#Page_192">192</a>, <a href="#Page_203">203</a>
+
+Intestinal infestation, <a href="#Page_112">112</a>, <a href="#Page_133">133</a>
+  myasis, <a href="#Page_137">137</a>
+
+Isosoma, <a href="#Page_69">69</a>
+
+Itch, <a href="#Page_73">73-74</a>
+  mite, <a href="#Page_73">73</a>
+  Norwegian, <a href="#Page_77">77</a>
+
+Ixodes, <a href="#Pg_260">260</a>
+  ricinus, <a href="#Page_66">66</a>, <a href="#Page_225">225</a>
+  scapularis, <a href="#Page_66">66</a>
+
+Ixodidæ, <a href="#Page_64">64-65</a>
+
+Ixodoidea, <a href="#Page_62">62</a>
+
+
+Janthinosoma lutzi, <a href="#Page_116">116</a>
+
+Jigger, <a href="#Page_60">60</a>
+
+Johannseniella, <a href="#Page_110">110</a>, <a href="#Page_288">288</a>
+
+Journal of Tropical Medicine and Hygiene, <a href="#Page_36">36</a>
+
+Julus terrestris, <a href="#Page_25">25</a>
+
+June bug, <a href="#Page_185">185</a>
+
+
+Kala-azar, <a href="#Page_220">220</a>
+
+Karakurte, <a href="#Page_14">14</a>
+
+Katipo, <a href="#Page_14">14</a>
+
+King, A. F. A., <a href="#Page_3">3</a>
+
+Kircher, Athanasius, <a href="#Page_1">1</a>, <a href="#Page_8">8</a>
+
+Kissing-bug, <a href="#Page_31">31</a>
+
+
+Labium, <a href="#Page_29">29</a>, <a href="#Page_80">80</a>
+
+Labrum, <a href="#Page_28">28</a>, <a href="#Page_80">80</a>
+
+Lachnosterna, <a href="#Page_185">185</a>
+
+Lælaps, <a href="#Pg_266">266</a>
+
+Lagoa crispata, <a href="#Page_45">45</a>
+
+Lamblia intestinalis, <a href="#Page_154">154</a>
+
+Langer, Josef, <a href="#Page_37">37</a>
+
+Larder beetles, <a href="#Page_135">135</a>
+
+Latrodectus, <a href="#Page_12">12</a>, <a href="#Page_14">14</a>, <a href="#Page_17">17</a>
+  mactans, <a href="#Page_15">15</a>
+
+Leishmanioses, <a href="#Page_220">220</a>
+
+Lenticular fever, <a href="#Page_237">237</a>
+
+Lepidoptera, <a href="#Page_274">274</a>
+
+Lepidopterous larvæ, <a href="#Page_134">134</a>
+
+Leprosy, <a href="#Page_252">252</a>
+
+Leptidæ, <a href="#Page_112">112</a>
+
+Leptis, <a href="#Page_295">295</a>
+
+Leptus, <a href="#Page_60">60</a>, <a href="#Page_273">273</a>
+
+Lice, <a href="#Page_80">80</a>
+
+Linguatulina, <a href="#Page_258">258</a>
+
+Liponyssus, <a href="#Page_265">265</a>
+
+L&oelig;mopsylla, <a href="#Page_172">172</a>, <a href="#Page_317">317</a>
+
+Lone star tick, <a href="#Page_228">228</a>
+
+Louse, body, <a href="#Page_84">84</a>
+  crab, <a href="#Page_85">85</a>
+  dog, <a href="#Page_176">176</a>
+  head, <a href="#Page_82">82</a>
+  pubic, <a href="#Page_85">85</a>
+
+Lucilia, <a href="#Page_136">136</a>, <a href="#Page_312">312</a>
+
+Lycosa tarantula, <a href="#Page_10">10</a>
+
+Lycosidæ, <a href="#Page_10">10</a>
+
+Lyctocoris, <a href="#Page_279">279</a>
+
+Lygus pratensis, <a href="#Page_33">33</a><span class="pagenum"><a name="Page_345" id="Page_345">[Pg 345]</a></span>
+
+Lymphangitis, <a href="#Page_67">67</a>
+
+Lymph scrotum, <a href="#Page_178">178</a>
+
+Lyperosia, <a href="#Page_304">304</a>
+
+Lyperosiops, <a href="#Page_305">305</a>
+
+
+Macloskie, <a href="#Page_34">34</a>
+
+Maggots, rat-tail, <a href="#Page_137">137</a>
+
+Magnes sive de Arte Magnetica, <a href="#Page_8">8</a>
+
+Malaria, <a href="#Page_186">186</a>
+
+Malmigniatte, <a href="#Page_14">14</a>
+
+Mandibles, <a href="#Page_28">28</a>, <a href="#Page_80">80</a>
+
+Mange, <a href="#Page_73">73-75</a>
+
+Margaropus, <a href="#Page_237">237</a>, <a href="#Page_264">264</a>
+  annulatus, <a href="#Page_223">223</a>
+
+Masked bed-bug hunter, <a href="#Page_32">32</a>
+
+Mastigoproctus giganteus, <a href="#Page_19">19</a>, <a href="#Page_80">80</a>
+
+Maxillæ, <a href="#Page_28">28</a>
+
+Meal infesting species, <a href="#Page_135">135</a>
+
+Melanin granules, <a href="#Page_189">189</a>
+
+Melanolestes, <a href="#Page_280">280</a>
+  picipes, <a href="#Page_32">32</a>
+
+Mena-vodi, <a href="#Page_14">14</a>
+
+Mercurialis, <a href="#Page_1">1</a>
+
+Merozoites, <a href="#Page_190">190</a>
+
+Metamorphosis, <a href="#Page_80">80</a>
+
+Miana bug, <a href="#Page_63">63</a>
+
+Microgametoblast, <a href="#Page_192">192</a>
+
+Midges, <a href="#Page_107">107</a>
+
+Migratory ookinete, <a href="#Page_192">192</a>
+
+Millipedes, <a href="#Page_25">25</a>, <a href="#Page_257">257</a>
+
+Mites, <a href="#Page_23">23</a>, <a href="#Page_58">58</a>
+
+Monieziella, <a href="#Page_269">269</a>
+
+Mosquitoes, <a href="#Page_33">33</a>, <a href="#Page_97">97</a>, <a href="#Page_178">178</a>, <a href="#Page_196">196</a>, <a href="#Page_250">250</a>
+  treatment for bites of, <a href="#Page_34">34</a>, <a href="#Page_36">36</a>, <a href="#Page_102">102</a>
+
+Musca, <a href="#Page_137">137</a>, <a href="#Page_307">307</a>
+  domestica, <a href="#Page_139">139</a>, <a href="#Page_145">145</a>, <a href="#Page_146">146</a>, <a href="#Page_157">157</a>, <a href="#Page_162">162</a>
+
+Muscidæ, <a href="#Page_117">117</a>
+
+Muscina, <a href="#Page_137">137</a>, <a href="#Page_146">146</a>, <a href="#Page_307">307</a>
+  stabulans, <a href="#Page_140">140</a>
+
+Mutualism, <a href="#Page_57">57</a>
+
+Myasis, <a href="#Page_112">112</a>, <a href="#Page_135">135</a>
+  intestinal, <a href="#Page_135">135-140</a>
+  nasal, <a href="#Page_141">141</a>
+
+Mycterotypus, <a href="#Page_287">287</a>
+
+Myiospila, <a href="#Page_146">146</a>, <a href="#Page_307">307</a>
+
+Myriapoda, <a href="#Page_25">25</a>, <a href="#Page_132">132</a>, <a href="#Page_257">257</a>
+
+
+Nagana, <a href="#Page_165">165</a>, <a href="#Page_214">214</a>
+
+Nasal infestation, <a href="#Page_114">114</a>, <a href="#Page_133">133</a>
+
+Necrobia, <a href="#Page_135">135</a>
+
+Nematode parasite, <a href="#Page_182">182</a>
+
+Nepa, <a href="#Page_28">28</a>
+
+Nephrophages sanguinarius, <a href="#Page_132">132</a>
+
+Nettling insects, <a href="#Page_43">43</a>
+  larvæ, poison of, <a href="#Page_53">53</a>
+
+Neurasthenia, <a href="#Page_89">89</a>
+
+Nits, <a href="#Page_86">86</a>
+
+North African Relapsing Fever, <a href="#Page_234">234</a>
+
+Norwegian itch, <a href="#Page_77">77</a>
+
+No-see-ums, <a href="#Page_109">109</a>
+
+Not&oelig;dres, <a href="#Page_269">269</a>
+  cati, <a href="#Page_78">78</a>
+
+Notonecta, <a href="#Page_28">28</a>, <a href="#Page_277">277</a>
+
+Notonectidæ, <a href="#Page_30">30</a>
+
+Nott, Dr. Josiah, <a href="#Page_2">2</a>
+
+Nuttall, <a href="#Page_34">34</a>
+
+
+Occipital headaches, <a href="#Page_138">138</a>
+
+Oecacta, <a href="#Page_288">288</a>
+
+Oeciacus, <a href="#Page_279">279</a>
+
+&OElig;sophageal diverticula, <a href="#Page_35">35</a>
+
+Oestridæ, <a href="#Page_112">112</a>, <a href="#Page_136">136</a>
+
+Oestris ovis, <a href="#Page_113">113</a>
+
+Oestrus, <a href="#Page_298">298</a>
+  oocyst, <a href="#Page_192">192</a>
+  ookinete, <a href="#Page_192">192</a>
+
+Opsicoetes personatus, <a href="#Page_32">32</a>
+
+Opthalmia, <a href="#Page_155">155</a>
+  nodosa, <a href="#Page_52">52</a>
+
+Oriental sore, <a href="#Page_221">221</a>
+
+Ornithodoros, <a href="#Page_65">65</a>, <a href="#Pg_260">260</a>
+  moubata, <a href="#Page_220">220</a>, <a href="#Page_230">230</a>
+
+Orthotylus flavosparsus, <a href="#Page_33">33</a>
+
+Ornithomyia, <a href="#Page_286">286</a>
+
+Oroya, <a href="#Page_253">253</a>
+
+Oscinus, <a href="#Page_297">297</a>
+
+Otiobius, <a href="#Page_259">259</a>
+  megnini, <a href="#Page_65">65</a>
+
+Otodectes, <a href="#Page_271">271</a>
+
+
+Pangonia, <a href="#Page_294">294</a>
+
+Pappatici fever, <a href="#Page_96">96</a>
+
+Parasimulium, <a href="#Page_286">286</a>
+
+Parasite, <a href="#Page_3">3</a>, <a href="#Page_57">57</a>, <a href="#Page_131">131</a>, <a href="#Page_134">134</a>, <a href="#Page_182">182</a>
+  accidental, <a href="#Page_3">3</a>, <a href="#Page_131">131</a>, <a href="#Page_134">134</a>
+  facultative, <a href="#Page_3">3</a>, <a href="#Page_57">57</a>, <a href="#Page_131">131</a><span class="pagenum"><a name="Page_346" id="Page_346">[Pg 346]</a></span>
+  nematode, <a href="#Page_182">182</a>
+  stationary, <a href="#Page_57">57</a>
+  temporary, <a href="#Page_57">57</a>
+  true, <a href="#Page_3">3</a>
+
+Parasitism, accidental, <a href="#Page_134">134</a>
+
+Pathogenic bacteria, <a href="#Page_152">152</a>
+  organisms, <a href="#Page_144">144</a>, <a href="#Page_164">164</a>
+
+Pawlowsky, <a href="#Page_81">81</a>
+
+Pediculoides, <a href="#Page_267">267</a>
+  ventricosus, <a href="#Page_69">69</a>, <a href="#Page_72">72</a>
+
+Pediculosis, <a href="#Page_81">81</a>
+
+Pediculus, <a href="#Page_275">275</a>
+  corporis, <a href="#Page_84">84</a>, <a href="#Page_233">233</a>, <a href="#Page_238">238</a>
+  humanus, <a href="#Page_82">82</a>, <a href="#Page_173">173</a>
+
+Pellagra, <a href="#Page_162">162</a>, <a href="#Page_246">246</a>
+
+Pernicious fever, <a href="#Page_186">186</a>
+
+Pest, <a href="#Page_166">166</a>
+
+Phidippus audax, <a href="#Page_19">19</a>
+
+Philæmatomyia, <a href="#Page_306">306</a>
+
+Phisalix, <a href="#Page_13">13</a>, <a href="#Page_43">43</a>
+
+Phlebotomus, <a href="#Page_289">289</a>
+  papatasii, <a href="#Page_94">94</a>
+  verrucarum, <a href="#Page_254">254</a>
+  vexator, <a href="#Page_95">95</a>
+
+Phora, <a href="#Page_295">295</a>
+
+Phormia, <a href="#Page_136">136</a>
+
+Phormictopus carcerides, <a href="#Page_13">13</a>
+
+Phthirus pubis, <a href="#Page_85">85</a>, <a href="#Page_275">275</a>
+
+Phortica, <a href="#Page_296">296</a>
+
+Pieris brassicæ, <a href="#Page_56">56</a>
+
+Piophila, <a href="#Page_297">297</a>
+
+Piophila casei, <a href="#Page_136">136</a>, <a href="#Page_137">137</a>
+
+Piroplasmosis, <a href="#Page_222">222</a>
+
+Plague, <a href="#Page_166">166</a>
+  bubonic, <a href="#Page_166">166</a>, <a href="#Page_169">169</a>, <a href="#Page_170">170</a>
+  pneumonic, <a href="#Page_167">167</a>
+
+Plasmodium, <a href="#Page_186">186</a>
+
+Platymetopius acutus, <a href="#Page_33">33</a>
+
+Plica palonica, <a href="#Page_83">83</a>
+
+Pneumonic, <a href="#Page_166">166</a>
+  plague, <a href="#Page_167">167</a>, <a href="#Page_173">173</a>
+
+Poisoning by nettling larvæ, <a href="#Page_53">53</a>
+
+Poison of spiders, <a href="#Page_7">7</a>
+
+Pollenia, <a href="#Page_308">308</a>
+  rudis, <a href="#Page_146">146</a>, <a href="#Page_147">147</a>
+
+Primary gland, <a href="#Page_28">28</a>
+
+Prionurus citrinus, <a href="#Page_20">20</a>
+
+Prosimulium, <a href="#Page_286">286</a>
+
+Protocalliphora, <a href="#Page_136">136</a>, <a href="#Page_312">312</a>
+
+Protozoan blood parasite, <a href="#Page_165">165</a>
+
+Pseudo-tubercular, <a href="#Page_52">52</a>
+
+Psorophora, <a href="#Page_293">293</a>
+
+Psoroptes, <a href="#Pg_270">270</a>
+
+Psychodidæ, <a href="#Page_94">94</a>
+
+Pulex, <a href="#Page_120">120</a>, <a href="#Page_124">124</a>, <a href="#Page_126">126</a>, <a href="#Page_172">172</a>, <a href="#Page_317">317</a>
+  cheopis, <a href="#Page_172">172</a>
+  irritans, <a href="#Page_124">124</a>
+  penetrans, <a href="#Page_126">126</a>
+  serraticeps, <a href="#Page_120">120</a>
+
+Pulvillus, <a href="#Page_150">150</a>
+
+Punkies, <a href="#Page_109">109</a>
+
+Pycnosoma, <a href="#Page_308">308</a>
+
+
+Rasahus, <a href="#Page_280">280</a>
+  thoracicus, <a href="#Page_32">32</a>
+
+Rat fleas, <a href="#Page_120">120</a>, <a href="#Page_124">124</a>, <a href="#Page_171">171</a>
+
+Rat louse, <a href="#Page_213">213</a>
+
+Red bugs, <a href="#Page_70">70-72</a>
+
+Reduviidæ, <a href="#Page_31">31</a>
+
+Reduviolus, <a href="#Page_280">280</a>
+
+Reduvius, <a href="#Page_282">282</a>
+  personatus, <a href="#Page_32">32</a>
+
+Redwater fever, <a href="#Page_222">222</a>
+
+Relapsing fever, <a href="#Page_230">230</a>, <a href="#Page_233">233</a>
+
+Rhi&oelig;strus nasalis, <a href="#Page_115">115</a>
+
+Rhipicentor, <a href="#Page_264">264</a>
+
+Rhipicephalus, <a href="#Page_264">264</a>
+
+Rhizoglyphus, <a href="#Page_269">269</a>
+
+Rhodnius, <a href="#Page_281">281</a>
+
+Rocky Mountain Spotted Fever, <a href="#Page_226">226</a>
+  spotted fever tick, <a href="#Page_67">67</a>
+
+Russian gad-fly, <a href="#Page_115">115</a>
+
+
+St. Vitus's or St. John's dance, <a href="#Page_8">8</a>
+
+Salivary syringe, <a href="#Page_28">28</a>
+
+Sand-flies, <a href="#Page_109">109</a>, <a href="#Page_250">250</a>
+
+Sanguinetti, <a href="#Page_11">11</a>
+
+Sarcophaga, <a href="#Page_136">136</a>, <a href="#Page_142">142</a>, <a href="#Page_143">143</a>
+
+Sarcophila, <a href="#Page_302">302</a>
+
+Sarcopsylla, <a href="#Page_317">317</a>
+  penetrans, <a href="#Page_126">126</a>
+
+Sarcoptes, <a href="#Pg_270">270</a>
+  minor, <a href="#Page_78">78</a>
+  scabiei, <a href="#Page_73">73</a>
+
+Sarcoptidæ, <a href="#Page_72">72</a>
+
+Scabies, <a href="#Page_172">72</a>, <a href="#Page_73">73</a>, <a href="#Page_74">74</a>, <a href="#Page_75">75</a><span class="pagenum"><a name="Page_347" id="Page_347">[Pg 347]</a></span>
+
+Scaurus striatus, <a href="#Page_177">177</a>
+
+Schaudinn, <a href="#Page_34">34</a>
+
+Schizont, <a href="#Page_189">189</a>, <a href="#Page_190">190</a>
+
+Scholeciasis, <a href="#Page_134">134</a>
+
+Scolopendra morsitans, <a href="#Page_26">26</a>
+
+Scorpions, <a href="#Page_20">20</a>
+  poison of, <a href="#Page_21">21</a>
+
+Screw worm fly, <a href="#Page_140">140</a>
+
+Sepsidæ, <a href="#Page_296">296</a>
+
+Sepsis, <a href="#Page_136">136</a>, <a href="#Page_297">297</a>
+
+Shipley, <a href="#Page_34">34</a>
+
+Sibine, <a href="#Page_46">46</a>
+
+Silvius, <a href="#Page_294">294</a>
+
+Simple carriers, <a href="#Page_4">4</a>, <a href="#Page_144">144</a>
+
+Simuliidæ, <a href="#Page_33">33</a>, <a href="#Page_104">104</a>
+
+Simulium, <a href="#Page_247">247</a>, <a href="#Page_249">249</a>, <a href="#Page_286">286</a>, <a href="#Page_321">321</a>
+  pictipes, <a href="#Page_104">104</a>
+
+Siphonaptera, <a href="#Page_119">119</a>, <a href="#Page_274">274</a>, <a href="#Page_316">316</a>
+
+Siphunculata, <a href="#Page_80">80</a>, <a href="#Page_275">275</a>
+
+Sitotroga cerealella, <a href="#Page_69">69</a>
+
+Skippers, <a href="#Page_137">137</a>
+
+Sleeping sickness, <a href="#Page_166">166</a>, <a href="#Page_215">215</a>
+
+Snipe-flies, <a href="#Page_112">112</a>
+
+Solpugida, <a href="#Page_22">22</a>
+
+Spanish fly, <a href="#Page_54">54</a>
+
+Spermatozoa, <a href="#Page_192">192</a>
+
+Spinose ear-tick, <a href="#Page_65">65</a>
+
+Spirochæta, <a href="#Page_35">35</a>
+  berberi, <a href="#Page_234">234</a>
+  duttoni, <a href="#Page_234">234</a>
+
+Spirochætosis, <a href="#Page_235">235</a>
+
+Sporozoite, <a href="#Page_189">189</a>
+
+Spotted fever, <a href="#Page_67">67</a>, <a href="#Page_226">226</a>
+
+Squirrel flea, <a href="#Page_123">123</a>
+
+Stable-fly, <a href="#Page_137">137</a>, <a href="#Page_160">160</a>, <a href="#Page_163">163</a>, <a href="#Page_165">165</a>
+
+Stegomyia, <a href="#Page_182">182</a>, <a href="#Page_293">293</a>
+  calopus, <a href="#Page_206">206</a>
+  fasciata, <a href="#Page_206">206</a>
+
+Stomoxys, <a href="#Page_137">137</a>, <a href="#Page_305">305</a>
+  calcitrans, <a href="#Page_117">117</a>, <a href="#Page_146">146</a>, <a href="#Page_160">160</a>, <a href="#Page_161">161</a>, <a href="#Page_165">165</a>, <a href="#Page_242">242</a>
+
+Straw-worm, <a href="#Page_69">69</a>
+
+Stygeromyia, <a href="#Page_305">305</a>
+
+Sucking stomach, <a href="#Page_35">35</a>
+
+Sulphur ointment, <a href="#Page_77">77</a>
+
+Surra, <a href="#Page_165">165</a>
+
+Symbiosis, <a href="#Page_57">57</a>
+
+Symphoromyia, <a href="#Page_112">112</a>, <a href="#Page_295">295</a>
+
+
+Tabanidæ, <a href="#Page_110">110</a>
+
+Tabanus, <a href="#Page_110">110</a>, <a href="#Page_166">166</a>, <a href="#Page_294">294</a>
+  striatus, <a href="#Page_165">165</a>
+
+Taenia, <a href="#Page_175">175</a>
+
+Tapeworm, <a href="#Page_4">4</a>, <a href="#Page_176">176</a>
+
+Tarantella, <a href="#Page_8">8</a>
+
+Tarantism, <a href="#Page_8">8</a>
+
+Tarantula, <a href="#Page_10">10</a>
+
+Tarsonemidæ, <a href="#Page_69">69</a>
+
+Tarsonemus, <a href="#Page_267">267</a>
+
+Tenebrionid beetles, <a href="#Page_127">127</a>
+
+Tersesthes, <a href="#Page_110">110</a>, <a href="#Page_288">288</a>
+
+Tetanus, <a href="#Page_129">129</a>
+
+Tetranychus, <a href="#Page_273">273</a>
+
+Texas fever, <a href="#Page_220">220-223</a>
+
+Three-day fever, <a href="#Page_96">96</a>
+
+Tick, <a href="#Page_23">23</a>, <a href="#Page_226">226</a>
+  bites, Treatment of, <a href="#Page_68">68</a>
+  fever, <a href="#Page_230">230</a>
+  paralysis, <a href="#Page_67">67</a>
+
+Treatment,
+  Bee stings, <a href="#Page_36">36</a>, <a href="#Page_41">41</a>
+  Bites of,
+    Bed-bugs, <a href="#Page_90">90</a>, <a href="#Page_93">93</a>
+    Blackflies, <a href="#Page_107">107</a>
+    Buffalo flies, <a href="#Page_107">107</a>
+    Bugs, <a href="#Page_31">31</a>, <a href="#Page_33">33</a>
+    Centipedes, <a href="#Page_26">26</a>, <a href="#Page_27">27</a>
+    Chiggers, <a href="#Page_127">127</a>
+    Chigoes, <a href="#Page_127">127</a>
+    Fleas, <a href="#Page_127">127</a>
+    Harvest mites, <a href="#Page_61">61</a>
+    Jiggers, <a href="#Page_129">129</a>
+    Lice, <a href="#Page_83">83</a>, <a href="#Page_85">85</a>
+    Mosquitoes, <a href="#Page_34">34</a>, <a href="#Page_36">36</a>, <a href="#Page_102">102</a>
+    Phlebotomus flies, <a href="#Page_97">97</a>
+    Sand flies, <a href="#Page_96">96</a>, <a href="#Page_107">107</a>, <a href="#Page_109">109</a>
+    Scorpions, <a href="#Page_22">22</a>, <a href="#Page_23">23</a>
+    Spiders, <a href="#Page_19">19</a>
+    Ticks, <a href="#Page_61">61</a>, <a href="#Page_68">68</a>, <a href="#Page_72">72</a>
+    Ticks, ear, <a href="#Page_65">65</a>
+  Blister beetle poison, <a href="#Page_55">55</a>
+  Brown-tail moth rash, <a href="#Page_45">45</a>
+  Cantharidin poison, <a href="#Page_55">55</a>
+  Caterpillar rash, <a href="#Page_45">45</a>
+  Ear ticks, <a href="#Page_65">65</a>
+  House fly control, <a href="#Page_156">156</a>, <a href="#Page_160">160</a>
+  Itch, <a href="#Page_77">77</a><span class="pagenum"><a name="Page_348" id="Page_348">[Pg 348]</a></span>
+  Itch, grocer's, <a href="#Page_72">72</a>
+  Lice, <a href="#Page_85">85</a>
+  Nasal myasis, <a href="#Page_143">143</a>
+  Rocky Mt. spotted fever, <a href="#Page_228">228</a>, <a href="#Page_229">229</a>
+  Rash, caterpillar, <a href="#Page_45">45</a>
+  Scabies, <a href="#Page_77">77</a>
+  Sleeping sickness control, <a href="#Page_218">218</a>
+  Spotted fever, <a href="#Page_228">228</a>, <a href="#Page_229">229</a>
+  Stings, bee, <a href="#Page_36">36</a>, <a href="#Page_41">41</a>
+  Typhus fever, prophylaxis, <a href="#Page_239">239</a>
+
+Trichodectes canis, <a href="#Page_176">176</a>
+
+Trichoma, <a href="#Page_82">82</a>
+
+Trineura, <a href="#Page_295">295</a>
+
+Trochosa singoriensis, <a href="#Page_11">11</a>
+
+Trombidium, <a href="#Page_60">60</a>, <a href="#Page_273">273</a>
+
+True insects, <a href="#Page_80">80</a>
+
+Trypanosoma, <a href="#Page_35">35</a>
+
+Trypanosoma, brucei, <a href="#Page_165">165</a>
+
+Trypanosoma cruzi, <a href="#Page_219">219</a>
+
+Trypanosoma lewisi, <a href="#Page_213">213</a>
+
+Trypanosomiases, <a href="#Page_212">212</a>
+
+Trypanosomiasis, <a href="#Page_165">165</a>, <a href="#Page_219">219</a>
+
+Tsetse flies, <a href="#Page_117">117</a>, <a href="#Page_166">166</a>, <a href="#Page_214">214</a>, <a href="#Page_219">219</a>
+
+Tsetse flies disease, <a href="#Page_165">165</a>
+
+Tuberculosis, <a href="#Page_155">155</a>
+
+Tumbu-fly, <a href="#Page_118">118</a>
+
+Tydeus, <a href="#Page_271">271</a>
+
+Typhoid, <a href="#Page_155">155</a>
+
+Typhoid fever, <a href="#Page_154">154</a>
+
+Typhus, <a href="#Page_237">237</a>
+
+Typhus fever, <a href="#Page_237">237</a>
+
+Tyroglyphus, <a href="#Page_72">72</a>, <a href="#Page_131">131</a>, <a href="#Pg_268">268</a>
+
+Dr. Tyzzer, <a href="#Page_49">49</a>
+
+
+Uranotænia, <a href="#Page_292">292</a>
+
+
+Vancoho, <a href="#Page_14">14</a>
+
+Varicose groin glands, <a href="#Page_178">178</a>
+
+Verruga peruviana, <a href="#Page_253">253</a>
+
+Vescicating insects, <a href="#Page_54">54</a>
+
+
+Wanzenspritze, <a href="#Page_29">29</a>
+
+Warble-flies, <a href="#Page_112">112</a>
+
+Wasps, <a href="#Page_43">43</a>
+
+Whip-scorpions, <a href="#Page_19">19</a>
+
+Wohlfahrtia, <a href="#Page_143">143</a>, <a href="#Page_302">302</a>
+
+Wolf-spiders, <a href="#Page_10">10</a>
+
+Wyeomyia smithii, <a href="#Page_101">101</a>, <a href="#Page_293">293</a>
+
+
+Xenopsylla, <a href="#Page_172">172</a>, <a href="#Page_317">317</a>
+
+Xenopsylla cheopis, <a href="#Page_171">171</a>, <a href="#Page_124">124</a>
+
+Xestopsylla, <a href="#Page_317">317</a>
+
+
+Yaws, <a href="#Page_2">2</a>
+
+Yellow fever, <a href="#Page_196">196</a>, <a href="#Page_203">203</a>, <a href="#Page_205">205</a>
+</pre>
+
+<div class="bbox" style="padding:1em;">
+<h3>TRANSCRIBERS' NOTES</h3>
+
+<p>The following discrepancies in the text are as in the original:</p>
+<ul>
+<li>The inconsistent hyphenation of the following:
+<ul>
+<li>assassin-bugs/assassin bugs;</li>
+<li>bedbug/bed-bug (and bedbugs);</li>
+<li>beekeeper/bee-keeper (and beekeepers);</li>
+<li>blackflies/black-flies;</li>
+<li>blow-flies/blow flies;</li>
+<li>bluebottles/blue-bottles;</li>
+<li>bot-flies/bot flies;</li>
+<li>bristlelike/bristle-like;</li>
+<li>browntail/brown-tail;</li>
+<li>coextensive/co-extensive;</li>
+<li>deer-flies/deer flies;</li>
+<li>dorsocentral/dorso-central;</li>
+<li>ectoparasites/ecto-parasites;</li>
+<li>endoparasites/endo-parasites;</li>
+<li>flesh-fly/flesh fly (and flesh flies);</li>
+<li>hotbed/hot-bed;</li>
+<li>housefly/house-fly (and houseflies);</li>
+<li>horsefly/horse-fly (and horse flies);</li>
+<li>horse-manure/horse manure;</li>
+<li>midsummer/mid-summer;</li>
+<li>preeminently/pre-eminently;</li>
+<li>sandfly/sand-fly (and sandflies);</li>
+<li>screw-worm fly/screw worm fly;</li>
+<li>stable-fly/stable fly;</li>
+<li>subequal/sub-equal;</li>
+<li>subfamily/sub-family;</li>
+<li>subtropical/sub-tropical;</li>
+<li>tapeworm/tape-worm (and tapeworms);</li>
+<li>today/to-day;</li>
+<li>tsetse-flies/tsetse flies;</li>
+<li>widespread/wide-spread;</li>
+<li>wormlike/worm-like.</li>
+</ul>
+</li>
+<li>Inconsistent use of diaeresis in Aëdes/Aedes</li>
+<li>Inconsistent spelling of the following:
+<ul>
+<li>defence/defense;</li>
+<li>disc/disk;</li>
+<li>hemolysis/hæmolysis;</li>
+<li>hemolytic/hæmolytic;</li>
+<li>hexapod/hexopod;</li>
+<li>Levaditi/Lavaditi;</li>
+<li>metalescent/metallescent;</li>
+<li>Mitzmain/Mitzman;</li>
+<li>Neveau-Lemaire/Neveau-Lamaire;</li>
+<li>offence/offense;</li>
+<li>Phthirus/Phthirius</li>
+<li>Portschinsky/Portchinsky/Portchinski;</li>
+<li>travelled/traveled;</li>
+<li>ventra-/ventro-;</li>
+<li>Villot/Villet;</li>
+<li>Wohlfartia/Wohlfahrtia;</li>
+</ul>
+</li>
+<li>Inconsistent use of ligatures in Taenia/Tænia</li>
+</ul>
+<p>toxine, insiduous, efficaceous, cyanid are spelt as in the original</p>
+<p>In the first paragraph of chapter XII, "the student might not be lead"
+is as in the original. Lead perhaps should be led</p>
+<p>There is no Figure 147 in the original</p>
+<p>In the bibliography, the entry for Vaughan without a text specified is
+as in the original</p>
+
+</div>
+
+
+
+
+
+
+
+
+<pre>
+
+
+
+
+
+End of the Project Gutenberg EBook of Handbook of Medical Entomology, by 
+William Albert Riley and Oskar Augustus Johanssen
+
+*** END OF THIS PROJECT GUTENBERG EBOOK HANDBOOK OF MEDICAL ENTOMOLOGY ***
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@@ -0,0 +1,16506 @@
+The Project Gutenberg EBook of Handbook of Medical Entomology, by 
+William Albert Riley and Oskar Augustus Johanssen
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Handbook of Medical Entomology
+
+Author: William Albert Riley
+        Oskar Augustus Johanssen
+
+Release Date: November 11, 2010 [EBook #34279]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK HANDBOOK OF MEDICAL ENTOMOLOGY ***
+
+
+
+
+Produced by Bryan Ness, Iris Schimandle, Brownfox and the
+Online Distributed Proofreading Team at http://www.pgdp.net
+(This file was produced from images generously made
+available by The Internet Archive/American Libraries.)
+
+
+
+
+
+Transcriber's Note: ae character replaced with ae. Accents have been
+removed. The degree symbol has been replaced with ^o. The times symbol
+has been replaced with lowercase x. The symbol mu/micro has been
+replaced with lowercase u.
+
+
+
+
+[Illustration: Some early medical entomology. Athanasius Kircher's
+illustration of the Italian tarantula and the music prescribed as an
+antidote for the poison of its bite. (1643).]
+
+
+
+
+HANDBOOK OF MEDICAL
+
+ENTOMOLOGY
+
+WM. A. RILEY, PH.D.
+
+Professor of Insect Morphology and Parasitology, Cornell University
+
+and
+
+O. A. JOHANNSEN, PH.D.
+
+Professor of Biology, Cornell University
+
+[Illustration]
+
+ITHACA, NEW YORK
+
+THE COMSTOCK PUBLISHING COMPANY
+
+1915
+
+
+COPYRIGHT, 1915
+
+BY THE COMSTOCK PUBLISHING COMPANY,
+
+ITHACA, N. Y.
+
+
+Press of W. F. Humphrey
+Geneva, N. Y.
+
+
+
+
+PREFACE
+
+
+The Handbook of Medical Entomology is the outgrowth of a course of
+lectures along the lines of insect transmission and dissemination of
+diseases of man given by the senior author in the Department of
+Entomology of Cornell University during the past six years. More
+specifically it is an illustrated revision and elaboration of his "Notes
+on the Relation of Insects to Disease" published January, 1912.
+
+Its object is to afford a general survey of the field, and primarily to
+put the student of medicine and entomology in touch with the discoveries
+and theories which underlie some of the most important modern work in
+preventive medicine. At the same time the older phases of the
+subject--the consideration of poisonous and parasitic forms--have not
+been ignored.
+
+Considering the rapid shifts in viewpoint, and the development of the
+subject within recent years, the authors do not indulge in any hopes
+that the present text will exactly meet the needs of every one
+specializing in the field,--still less do they regard it as complete or
+final. The fact that the enormous literature of isolated articles is to
+be found principally in foreign periodicals and is therefore difficult
+of access to many American workers, has led the authors to hope that a
+summary of the important advances, in the form of a reference book may
+not prove unwelcome to physicians, sanitarians and working
+entomologists, and to teachers as a text supplementing lecture work in
+the subject.
+
+Lengthy as is the bibliography, it covers but a very small fraction of
+the important contributions to the subject. It will serve only to put
+those interested in touch with original sources and to open up the
+field. Of the more general works, special acknowledgment should be made
+to those of Banks, Brumpt, Castellani and Chalmers, Comstock, Hewitt,
+Howard, Manson, Mense, Neveau-Lemaire, Nuttall, and Stiles.
+
+To the many who have aided the authors in the years past, by suggestions
+and by sending specimens and other materials, sincerest thanks is
+tendered. This is especially due to their colleagues in the Department
+of Entomology of Cornell University, and to Professor Charles W. Howard,
+Dr. John Uri Lloyd, Mr. A. H. Ritchie, Dr. I. M. Unger, and Dr. Luzerne
+Coville.
+
+They wish to express indebtedness to the authors and publishers who have
+so willingly given permission to use certain illustrations. Especially
+is this acknowledgment due to Professor John Henry Comstock, Dr. L. O.
+Howard, Dr. Graham-Smith, and Professor G. H. T. Nuttall. Professor
+Comstock not only authorized the use of departmental negatives by the
+late Professor M. V. Slingerland (credited as M. V. S.), but generously
+put at their disposal the illustrations from the MANUAL FOR THE STUDY OF
+INSECTS and from the SPIDER BOOK. Figures 5 and 111 are from Peter's
+"Der Arzt und die Heilkunst in der deutschen Vergangenheit." It should
+be noted that on examining the original, it is found that Gottfried's
+figure relates to an event antedating the typical epidemic of dancing
+mania.
+
+                                                  WM. A. RILEY.
+                                                  O. A. JOHANNSEN.
+
+  CORNELL UNIVERSITY,
+  January, 1915.
+
+
+
+
+ADDITIONS AND CORRECTIONS
+
+vi line 11, for Heilkunft read Heilkunst.
+
+18 line 2, for tarsi read tarsus.
+
+32 line 21, and legend under fig. 23, for C. (Conorhinus) abdominalis
+      read Melanolestes abdominalis.
+
+47 legend under figure for 33c read 34.
+
+92 line 22 and 25, for sangiusugus read sanguisugus.
+
+116 legend under fig. 83, for Graham-Smith read Manson.
+
+136 line 10, from bottom, insert "ring" after "chitin".
+
+137 line 3, for meditatunda read meditabunda.
+
+145 line 7, from bottom, for Rs read R_5.
+
+158 line 20, for have read has.
+
+212 after the chapter heading insert "continued".
+
+219 line 10, from bottom, for Cornohinus read Conorhinus.
+
+266 line 1, fig. 158j refers to the female.
+
+272 line 5, insert "palpus" before "and leg".
+
+281 line 6, for discodial read discoidal.
+
+281 last line, insert "from" before "the".
+
+284 line 5, for "tubercle of" read "tubercle or".
+
+305 lines 19, 28, 44, page 306 lines 1, 9, 22, 27, 30, page 307 line 7,
+      page 309 lines 8, 11, for R_{4+5} read M_{1+2}.
+
+309 legend under fig. 168 add Bureau of Entomology.
+
+312 line 36, for "near apex" read "of M_{1+2}".
+
+313 running head, for Muscidae read Muscoidea.
+
+314 line 29, for "distal section" read "distally M_{1+2}".
+
+315 legend under fig. 172, for Pseudopyrellia read Orthellia, for
+      Lyperosia read Haematobia, for Umbana read urbana.
+
+323 and 325 legends under the figures, add "After Dr. J. H. Stokes".
+
+328 line 7 from bottom for Apiochaeta read Aphiochaeta.
+
+
+
+
+CONTENTS
+
+
+CHAPTER I
+
+INTRODUCTION                                                  1-5
+
+  Early suggestions regarding the transmission of disease by
+    insects.
+  The ways in which arthropods may affect the health of man.
+
+
+CHAPTER II
+
+ARTHROPODS WHICH ARE DIRECTLY POISONOUS                       6-56
+
+  The Araneida, or Spiders.
+    The tarantulas. Bird spiders. Spiders of the genus
+      Latrodectus. Other venomous spiders. Summary.
+  The Pedipalpida, or whip-scorpions.
+  The Scorpionida, or true scorpions.
+  The Solpugida, or solpugids.
+  The Acarina, or mites and ticks.
+  The Myriapoda, or centipedes and millipedes.
+  The Hexapoda, or true insects.
+    Piercing or biting insects poisonous to man.
+      Hemiptera, or true bugs.
+        The Notonectidae or back-swimmers. Belostomidae or giant
+          water-bugs. Reduviidae, or assassin bugs. Other
+          Hemiptera reported as poisonous to man.
+      Diptera; the midges, mosquitoes and flies.
+    Stinging insects.
+      Apis mellifica, the honey bee. Other stinging forms.
+    Nettling insects.
+      Lepidoptera, or butterflies and moths. Relief from
+        poisoning by nettling larvae.
+    Vescicating insects and those possessing other poisons
+      in their blood plasma. The blister beetles. Other
+      cryptotoxic insects.
+
+
+CHAPTER III
+
+PARASITIC ARTHROPODS AFFECTING MAN                            57-130
+
+  Acarina, or mites.
+    The Trombidiidae, or harvest mites.
+    The Ixodoidea, or ticks.
+      Argasidae. Ixodidae. Treatment of tick bites.
+    The mites.
+      Dermanyssidae. Tarsonemidae. Sarcoptidae, the itch mites.
+        Demodecidae, the follicle mites.
+  Hexapoda, or true insects.
+    Siphunculata, or sucking lice.
+    Hemiptera.
+    The bed-bug. Other bed-bugs.
+  Parasitic Diptera, or flies.
+    Psychodidae, or moth flies. Phlebotominae. Culicidae, or
+      mosquitoes. Simuliidae, or black-flies. Chironomidae, or
+      midges. Tabanidae, or horse-flies. Leptidae or
+      snipe-flies. Oestridae, or bot-flies. Muscidae, the
+      stable-fly and others.
+  Siphonaptera, or fleas.
+    The fleas affecting man, the dog, cat, and rat.
+    The true chiggers, or chigoes.
+
+CHAPTER IV
+
+ACCIDENTAL OR FACULTATIVE PARASITES                           131-143
+
+  Acarina, or mites.
+  Myriapoda, or centipedes and millipedes.
+  Lepidopterous larvae.
+  Coleoptera, or beetles.
+  Dipterous larvae causing myiasis.
+    Piophila casei, the cheese skipper. Chrysomyia macellaria,
+      the screw-worm fly. Calliphorinae, the bluebottles.
+      Muscinae, the house or typhoid fly, and others.
+      Anthomyiidae, the lesser house-fly and others.
+      Sarcophagidae, the flesh-flies.
+
+
+CHAPTER V
+
+ARTHROPODS AS SIMPLE CARRIERS OF DISEASE                      144-163
+
+  The house or typhoid fly as a carrier of disease.
+  Stomoxys calcitrans, the stable-fly.
+  Other arthropods which may serve as simple carriers of
+    pathogenic organisms.
+
+
+CHAPTER VI
+
+ARTHROPODS AS DIRECT INOCULATORS OF DISEASE GERMS             164-174
+
+  Some illustrations of direct inoculations of disease germs
+    by arthropods.
+  The role of fleas in the transmission of the plague.
+
+
+CHAPTER VII
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC ORGANISMS         175-185
+
+  Insects as intermediate hosts of tape-worms.
+  Arthropods as intermediate hosts of nematode worms.
+    Filariasis and mosquitoes.
+  Other nematode parasites of man and animals.
+
+
+CHAPTER VIII
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA          186-211
+
+  Mosquitoes and malaria.
+  Mosquitoes and yellow fever.
+
+
+CHAPTER IX
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA          212-229
+
+  Insects and trypanosomiases.
+    Fleas and lice as carriers of Trypanosoma lewisi.
+    Tsetse-flies and nagana.
+    Tsetse-flies and sleeping sickness in man.
+    South American trypanosomiasis.
+    Leishmanioses and insects.
+  Ticks and diseases of man and animals.
+    Cattle tick and Texas fever.
+    Ticks and Rocky Mountain Spotted fever of man.
+
+
+CHAPTER X
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA
+(CONTINUED)                                                   230-240
+
+  Arthropods and Spirochaetoses of man and animals.
+    African relapsing fever of man.
+    European relapsing fever.
+    North African relapsing fever of man.
+    Other types of relapsing fever of man.
+    Spirochaetosis of fowls.
+    Other spirochaete diseases of animals.
+  Typhus fever and lice.
+
+
+CHAPTER XI
+
+SOME POSSIBLE, BUT IMPERFECTLY KNOWN CASES OF
+ARTHROPOD TRANSMISSION OF DISEASE                             241-256
+
+  Infantile paralysis, or acute anterior poliomyelitis.
+  Pellagra. Leprosy. Verruga peruviana. Cancer.
+
+
+CHAPTER XII
+
+KEYS TO THE ARTHROPODS NOXIOUS TO MAN                         257-317
+
+  Crustacea.
+  Myriapoda, or centipedes and millipedes.
+  Arachnida (Orders of).
+    Acarina or ticks.
+  Hexapoda (Insecta).
+    Siphunculata and Hemiptera (lice and true bugs).
+    Diptera (mosquitoes, midges, and flies).
+    Siphonaptera (fleas).
+
+
+APPENDIX
+
+Hydrocyanic acid gas against household insects                318-320
+  Proportion of ingredients. A single room as an example.
+    Fumigating a large house. Precautions.
+
+Lesions produced by the bite of the black-fly                 321-326
+
+
+BIBLIOGRAPHY                                                  327-340
+
+
+INDEX                                                         341-348
+
+
+
+
+CHAPTER I.
+
+INTRODUCTION
+
+EARLY SUGGESTIONS REGARDING THE TRANSMISSION OF DISEASE BY INSECTS
+
+
+Until very recent years insects and their allies have been considered as
+of economic importance merely in so far as they are an annoyance or
+direct menace to man, or his flocks and herds, or are injurious to his
+crops. It is only within the past fifteen years that there has sprung
+into prominence the knowledge that in another and much more insiduous
+manner, they may be the enemy of mankind, that they may be among the
+most important of the disseminators of disease. In this brief period,
+such knowledge has completely revolutionized our methods of control of
+certain diseases, and has become an important weapon in the fight for
+the conservation of health.
+
+It is nowhere truer than in the case under consideration that however
+abrupt may be their coming into prominence, great movements and great
+discoveries do not arise suddenly. Centuries ago there was suggested the
+possibility that insects were concerned with the spread of disease, and
+from time to time there have appeared keen suggestions and logical
+hypotheses along this line, that lead us to marvel that the
+establishment of the truths should have been so long delayed.
+
+One of the earliest of these references is by the Italian physician,
+Mercurialis, who lived from 1530 to 1607, during a period when Europe
+was being ravaged by the dread "black death", or plague. Concerning its
+transmission he wrote: "There can be no doubt that flies feed on the
+internal secretions of the diseased and dying, then, flying away, they
+deposit their excretions on the food in neighboring dwellings, and
+persons who eat of it are thus infected."
+
+It would be difficult to formulate more clearly this aspect of the facts
+as we know them to-day, though it must always be borne in mind that we
+are prone to interpret such statements in the light of present-day
+knowledge. Mercurialis had no conception of the animate nature of
+contagion, and his statement was little more than a lucky guess.
+
+Much more worthy of consideration is the approval which was given to his
+view by the German Jesuit, Athanasius Kircher in 1658. One cannot read
+carefully his works without believing that long before Leeuwenhook's
+discovery, Kircher had seen the larger species of bacteria. Moreover, he
+attributed the production of disease to these organisms and formulated,
+vaguely, to be sure, a theory of the animate nature of contagion. It has
+taken two and a half centuries to accumulate the facts to prove his
+hypothesis.
+
+The theory of Mercurialis was not wholly lost sight of, for in the
+medical literature of the eighteenth century there are scattered
+references to flies as carriers of disease. Such a view seems even to
+have been more or less popularly accepted, in some cases. Gudger (1910),
+has pointed out that, as far back as 1769, Edward Bancroft, in "An Essay
+on the Natural History of Guiana in South America," wrote concerning the
+contagious skin-disease known as "Yaws": "It is usually believed that
+this disorder is communicated by the flies who have been feasting on a
+diseased object, to those persons who have sores, or scratches, which
+are uncovered; and from many observations, I think this is not
+improbable, as none ever receive this disorder whose skins are whole."
+
+Approaching more closely the present epoch, we find that in 1848, Dr.
+Josiah Nott, of Mobile, Alabama, published a remarkable article on the
+cause of yellow fever, in which he presented "reasons for supposing its
+specific cause to exist in some form of insect life." As a matter of
+fact, the bearing of Nott's work on present day ideas of the insect
+transmission of disease has been very curiously overrated. The common
+interpretation of his theory has been deduced from a few isolated
+sentences, but his argument appears quite differently when the entire
+article is studied. It must be remembered that he wrote at a period
+before the epoch-making discoveries of Pasteur and before the
+recognition of micro-organisms as factors in the cause of disease. His
+article is a masterly refutation of the theory of "malarial" origin of
+"all the fevers of hot climates," but he uses the term "insect" as
+applicable to the lower forms of life, and specific references to
+"mosquitoes," "aphids," "cotton-worms," and others, are merely in the
+way of similes.
+
+But, while Nott's ideas regarding the relation of insects to yellow
+fever were vague and indefinite, it was almost contemporaneously that
+the French physician, Louis Daniel Beauperthuy argued in the most
+explicit possible manner, that yellow fever and various others are
+transmitted by mosquitoes. In the light of the data which were available
+when he wrote, in 1853, it is not surprising that he erred by thinking
+that the source of the virus was decomposing matter which the mosquito
+took up and accidentally inoculated into man. Beauperthuy not only
+discussed the role of mosquitoes in the transmission of disease, but he
+taught, less clearly, that house-flies scatter pathogenic organisms. It
+seems that Boyce (1909) who quotes extensively from this pioneer work,
+does not go too far when he says "It is Dr. Beauperthuy whom we must
+regard as the father of the doctrine of insect-borne disease."
+
+In this connection, mention must be made of the scholarly article by the
+American physician, A. F. A. King who, in 1883, brought together an all
+but conclusive mass of argument in support of his belief that malaria
+was caused by mosquitoes. At about the same time, Finley, of Havana, was
+forcefully presenting his view that the mosquito played the chief role
+in the spread of yellow fever.
+
+To enter more fully into the general historical discussion is beyond the
+scope of this book. We shall have occasion to make more explicit
+references in considering various insect-borne diseases. Enough has been
+said here to emphasize that the recognition of insects as factors in the
+spread of disease was long presaged, and that there were not wanting
+keen thinkers who, with a background of present-day conceptions of the
+nature of disease, might have been in the front rank of investigators
+along these lines.
+
+
+THE WAYS IN WHICH ARTHROPODS MAY AFFECT THE HEALTH OF MAN
+
+When we consider the ways in which insects and their allies may affect
+the health of man, we find that we may treat them under three main
+groups:
+
+A. They may be directly poisonous. Such, for example, are the scorpions,
+certain spiders and mites, some of the predaceous bugs, and stinging
+insects. Even such forms as the mosquito deserve some consideration from
+this viewpoint.
+
+B. They may be parasitic, living more or less permanently on or in the
+body and deriving their sustenance from it.
+
+Of the parasitic arthropods we may distinguish, first, the _true
+parasites_, those which have adopted and become confirmed in the
+parasitic habit. Such are the itch mites, the lice, fleas, and the
+majority of the forms to be considered as parasitic.
+
+In addition to these, we may distinguish a group of _accidental_, or
+_facultative parasites_, species which are normally free-living, feeding
+on decaying substances, but which when accidentally introduced into the
+alimentary canal or other cavities of man, may exist there for a greater
+or less period. For example, certain fly larvae, or maggots, normally
+feeding in putrifying meat, have been known to occur as accidental or
+facultative parasites in the stomach of man.
+
+C. Finally, and most important, arthropods may be transmitters and
+disseminators of disease. In this capacity they may function in one of
+three ways; as _simple carriers_, as _direct inoculators_, or as
+_essential hosts_ of disease germs.
+
+As simple carriers, they may, in a wholly incidental manner, transport
+from the diseased to the healthy, or from filth to food, pathogenic
+germs which cling to their bodies or appendages. Such, for instance, is
+the relation of the house-fly to the dissemination of typhoid.
+
+As direct inoculators, biting or piercing species may take up from a
+diseased man or animal, germs which, clinging to the mouth parts, are
+inoculated directly into the blood of the insect's next victim. It it
+thus that horse-flies may occasionally transmit anthrax. Similarly,
+species of spiders and other forms which are ordinarily perfectly
+harmless, may accidentally convey and inoculate pyogenic bacteria.
+
+It is as essential hosts of disease germs that arthropods play their
+most important role. In such cases an essential part of the life cycle
+of the pathogenic organism is undergone in the insect. In other words,
+without the arthropod host the disease-producing organism cannot
+complete its development. As illustrations may be cited the relation of
+the Anopheles mosquito to the malarial parasite, and the relation of the
+cattle tick to Texas fever.
+
+A little consideration will show that this is the most important of the
+group. Typhoid fever is carried by water or by contaminated milk, and in
+various other ways, as well as by the house-fly. Kill all the
+house-flies and typhoid would still exist. On the other hand, malaria is
+carried only by the mosquito, because an essential part of the
+development of the malarial parasite is undergone in this insect.
+Exterminate all of the mosquitoes of certain species and the
+dissemination of human malaria is absolutely prevented.
+
+Once an arthropod becomes an essential host for a given parasite it may
+disseminate infection in three different ways:
+
+1. By infecting man or animals who ingest it. It is thus, for example,
+that man, dog, or cat, becomes infected with the double-pored dog
+tapeworm, _Dipylidium caninum_. The cysticercoid stage occurs in the
+dog louse, or in the dog or cat fleas, and by accidentally ingesting the
+infested insect the vertebrate becomes infested. Similarly, _Hymenolepis
+diminuta_, a common tapeworm of rats and mice, and occasional in man,
+undergoes part of its life cycle in various meal-infesting insects, and
+is accidentally taken up by its definitive host. It is very probable
+that man becomes infested with _Dracunculus (Filaria) medinensis_
+through swallowing in drinking water, the crustacean, _Cyclops_,
+containing the larvae of this worm.
+
+2. By infecting man or animals on whose skin or mucous membranes the
+insect host may be crushed or may deposit its excrement. The pathogenic
+organism may then actively penetrate, or may be inoculated by
+scratching. The causative organism of typhus fever is thus transmitted
+by the body louse.
+
+3. By direct inoculation by its bite, the insect host may transfer the
+parasite which has undergone development within it. The malarial
+parasite is thus transferred by mosquitoes; the Texas fever parasite by
+cattle ticks.
+
+
+
+
+CHAPTER II.
+
+ARTHROPODS WHICH ARE DIRECTLY POISONOUS
+
+
+Of all the myriads of insects and related forms, a very few are of
+direct use to man, some few others have forced his approbation on
+account of their wonderful beauty, but the great hordes of them are
+loathed or regarded as directly dangerous. As a matter of fact, only a
+very small number are in the slightest degree poisonous to man or to the
+higher animals. The result is that entomologists and lovers of nature,
+intent upon dissipating the foolish dread of insects, are sometimes
+inclined to go to the extreme of discrediting all statements of serious
+injury from the bites or stings of any species.
+
+Nevertheless, it must not be overlooked that poisonous forms do exist,
+and they must receive attention in a consideration of the ways in which
+arthropods may affect the health of man. Moreover, it must be recognized
+that "what is one man's meat, is another man's poison," and that in
+considering the possibilities of injury we must not ignore individual
+idiosyncrasies. Just as certain individuals may be poisoned by what, for
+others, are common articles of food, so some persons may be abnormally
+susceptible to insect poison. Thus, the poison of a bee sting may be of
+varying severity, but there are individuals who are made seriously sick
+by a single sting, regardless of the point of entry. Some individuals
+scarcely notice a mosquito bite, others find it very painful, and so
+illustrations of this difference in individuals might be multiplied.
+
+In considering the poisonous arthropods, we shall take them up by
+groups. The reader who is unacquainted with the systematic relationship
+of insects and their allies is referred to Chapter XII. No attempt will
+be made to make the lists under the various headings exhaustive, but
+typical forms will be discussed.
+
+
+ARANEIDA OR SPIDERS
+
+Of all the arthropods there are none which are more universally feared
+than are the spiders. It is commonly supposed that the majority, if not
+all the species are poisonous and that they are aggressive enemies of
+man and the higher animals, as well as of lower forms.
+
+That they really secrete a poison may be readily inferred from the
+effect of their bite upon insects and other small forms. Moreover, the
+presence of definite and well-developed poison glands can easily be
+shown. They occur as a pair of pouches (fig. 1) lying within the
+cephalothorax and connected by a delicate duct with a pore on the claw
+of the chelicera, or so-called "mandible" on the convex surface of the
+claw in such a position that it is not plugged and closed by the flesh
+of the victim.
+
+[Illustration: 1. Head of a spider showing poison gland (_c_) and its
+relation to the chelicera (_a_).]
+
+The glands may be demonstrated by slowly and carefully twisting off a
+chelicera and pushing aside the stumps of muscles at its base. By
+exercising care, the chitinous wall of the chelicera and its claw may be
+broken away and the duct traced from the gland to its outlet. The inner
+lining of the sac is constituted by a highly developed glandular
+epithelium, supported by a basement membrane of connective tissue and
+covered by a muscular layer, (fig. 2). The muscles, which are striated,
+are spirally arranged (fig. 1), and are doubtless under control of the
+spider, so that the amount of poison to be injected into a wound may be
+varied.
+
+[Illustration: 2. Section through a venom gland of Latrodectus
+13-guttatus showing the peritoneal, muscular and epithelial layers.
+After Bordas.]
+
+The poison itself, according to Kobert (1901), is a clear, colorless
+fluid, of oily consistency, acid reaction, and very bitter taste. After
+the spider has bitten two or three times, its supply is exhausted and
+therefore, as in the case of snakes, the poison of the bite decreases
+quickly with use, until it is null. To what extent the content of the
+poison sacs may contain blood serum or, at least, active principles of
+serum, in addition to a specific poison formed by the poison glands
+themselves, Kobert regards as an open question. He believes that the
+acid part of the poison, if really present, is formed by the glands and
+that, in the case of some spiders, the ferment-like, or better, active
+toxine, comes from the blood.
+
+[Illustration: 3. Chelicera of a spider.]
+
+But there is a wide difference between a poison which may kill an insect
+and one which is harmful to men. Certain it is that there is no lack of
+popular belief and newspaper records of fatal cases, but the evidence
+regarding the possibility of fatal or even very serious results for man
+is most contradictory. For some years, we have attempted to trace the
+more circumstantial newspaper accounts, which have come to our notice,
+of injury by North American species. The results have served, mainly, to
+emphasize the straits to which reporters are sometimes driven when there
+is a dearth of news. The accounts are usually vague and lacking in any
+definite clue for locating the supposed victim. In the comparatively few
+cases where the patient, or his physician, could be located, there was
+either no claim that the injury was due to spider venom, or there was no
+evidence to support the belief. Rarely, there was evidence that a
+secondary blood poisoning, such as might be brought about by the prick
+of a pin, or by any mechanical injury, had followed the bite of a
+spider. Such instances have no bearing on the question of the venomous
+nature of these forms.
+
+[Illustration: 4. The Italian tarantula (Lycosa tarantula). After
+Kobert.]
+
+The extreme to which unreasonable fear of the bites of spiders
+influenced the popular mind was evidenced by the accepted explanation of
+the remarkable dancing mania, or tarantism, of Italy during the Middle
+Ages. This was a nervous disorder, supposed to be due to the bite of a
+spider, the European tarantula (fig. 4), though it was also, at times,
+attributed to the bite of the scorpion. In its typical form, it was
+characterized by so great a sensibility to music that under its
+influence the victims indulged in the wildest and most frenzied dancing,
+until they sank to the ground utterly exhausted and almost lifeless. The
+profuse perspiring resulting from these exertions was supposed to be the
+only efficacious remedy for the disease. Certain forms of music were
+regarded as of especial value in treating this tarantism, and hence the
+name of "tarantella" was applied to them. Our frontispiece, taken from
+Athanasius Kircher's _Magnes sive de Arte Magnetica_, 1643 ed.,
+represents the most commonly implicated spider and illustrates some of
+what Fabre has aptly designated as "medical choreography."
+
+The disease was, in reality, a form of hysteria, spreading by sympathy
+until whole communities were involved, and was paralleled by the
+outbreaks of the so-called St. Vitus's or St. John's dance, which swept
+Germany at about the same time (fig. 5). The evidence that the spider
+was the cause of the first is about as conclusive as is that of the
+demoniacal origin of the latter. The true explanation of the outbreaks
+is doubtless to be found in the depleted physical and mental condition
+of the people, resulting from the wars and the frightful plagues which
+devastated all Europe previous to, and during these times. An
+interesting discussion of these aspects of the question is to be found
+in Hecker.
+
+[Illustration: 5. Dancing mania. Illustration from Johann Ludwig
+Gottfried's Chronik. 1632.]
+
+So gross has been the exaggeration and so baseless the popular fear
+regarding spiders that entomologists have been inclined to discredit all
+accounts of serious injury from their bites. Not only have the most
+circumstantial of newspaper accounts proved to be without foundation but
+there are on record a number of cases where the bite of many of the
+commoner species have been intentionally provoked and where the effect
+has been insignificant. Some years ago the senior author personally
+experimented with a number of the largest of our northern species, and
+with unexpected results. The first surprise was that the spiders were
+very unwilling to bite and that it required a considerable effort to get
+them to attempt to do so. In the second place, most of those
+experimented with were unable to pierce the skin of the palm or the back
+of the hand, but had to be applied to the thin skin between the fingers
+before they were able to draw blood. Unfortunately, no special attempt
+was made to determine, at the time, the species experimented with, but
+among them were _Theridion tepidariorum_, _Miranda aurantia_
+(_Argiopa_), _Metargiope trifasciata_, _Marxia stellata_, _Aranea
+trifolium_, _Misumena vatia_, and _Agelena naevia_. In no case was the
+bite more severe than a pin prick and though in some cases the sensation
+seemed to last longer, it was probably due to the fact that the mind was
+intent upon the experiment.
+
+[Illustration: 6. An American tarantula (Eurypelma hentzii). Natural
+size. After Comstock.]
+
+Similar experiments were carried out by Blackwell (1855), who believed
+that in the case of insects bitten, death did not result any more
+promptly than it would have from a purely mechanical injury of equal
+extent. He was inclined to regard all accounts of serious injury to man
+as baseless. The question cannot be so summarily dismissed, and we shall
+now consider some of the groups which have been more explicitly
+implicated.
+
+
+THE TARANTULAS.--In popular usage, the term "tarantula" is loosely
+applied to any one of a number of large spiders. The famous tarantulas
+of southern Europe, whose bites were supposed to cause the dancing
+mania, were Lycosidae, or wolf-spiders. Though various species of this
+group were doubtless so designated, the one which seems to have been
+most implicated was _Lycosa tarantula_ (L.), (fig. 4). On the other
+hand, in this country, though there are many Lycosidae, the term
+"tarantula" has been applied to members of the superfamily Avicularoidea
+(fig. 6), including the bird-spiders.
+
+Of the Old World Lycosidae there is no doubt that several species were
+implicated as the supposed cause of the tarantism. In fact, as we have
+already noted, the blame was sometimes attached to a scorpion. However,
+there seems to be no doubt that most of the accounts refer to the spider
+known as _Lycosa tarantula_.
+
+There is no need to enter into further details here regarding the
+supposed virulence of these forms, popular and the older medical
+literature abound in circumstantial accounts of the terrible effects of
+the bite. Fortunately, there is direct experimental evidence which bears
+on the question.
+
+Fabre induced a common south European wolf-spider, _Lycosa narbonensis_,
+to bite the leg of a young sparrow, ready to leave the nest. The leg
+seemed paralyzed as a result of the bite, and though the bird seemed
+lively and clamored for food the next day, on the third day it died. A
+mole, bitten on the nose, succumbed after thirty-six hours. From these
+experiments Fabre seemed justified in his conclusion that the bite of
+this spider is not an accident which man can afford to treat lightly.
+Unfortunately, there is nothing in the experiments, or in the symptoms
+detailed, to exclude the probability that the death of the animals was
+the result of secondary infection.
+
+As far back as 1693, as we learn from the valuable account of Kobert,
+(1901), the Italian physician, Sanguinetti allowed himself to be bitten
+on the arm by two tarantulas, in the presence of witnesses. The
+sensation was equivalent to that from an ant or a mosquito bite and
+there were no other phenomena the first day. On the second day the wound
+was inflamed and there was slight ulceration. It is clear that these
+later symptoms were due to a secondary infection. These experiments have
+been repeated by various observers, among whom may be mentioned Leon
+Dufour, Josef Erker and Heinzel, and with the similar conclusion that
+the bite of the Italian tarantula ordinarily causes no severe symptoms.
+In this conclusion, Kobert, though firmly convinced of the poisonous
+nature of some spiders, coincides. He also believes that striking
+symptoms may be simulated or artificially induced by patients in order
+to attract interest, or because they have been assured that the bite,
+under all circumstances, caused tarantism.
+
+The so-called Russian tarantula, _Trochosa singoriensis_ (fig. 7), is
+much larger than the Italian species, and is much feared. Kobert carried
+out a series of careful experiments with this species and his results
+have such an important bearing on the question of the venomous nature of
+the tarantula that we quote his summary. Experimenting first on nearly a
+hundred living specimens of _Trochosa singoriensis_ from Crimea he says
+that:
+
+"The tarantulas, no matter how often they were placed on the skin,
+handled, and irritated, could not be induced to bite either myself, the
+janitor, or the ordinary experimental animals. The objection that the
+tarantulas were weak and indifferent cannot stand, for as soon as I
+placed two of them on the shaved skin of a rabbit, instead of an attack
+on the animal, there began a furious battle between the two spiders,
+which did not cease until one of the two was killed."
+
+[Illustration: 7. Trochosa singoriensis. After Kobert.]
+
+"Since the spiders would not bite, I carefully ground up the fresh
+animals in physiological salt solution, preparing an extract which must
+have contained, in solution, all of the poisonous substance of their
+bodies. While in the case of _Latrodectus_, as we shall see, less than
+one specimen sufficed to yield an active extract, I have injected the
+filtered extract of six fresh Russian tarantulas, of which each one was
+much heavier than an average _Latrodectus_, subcutaneously and into the
+jugular vein of various cats without the animals dying or showing any
+special symptoms. On the basis of my experiments I can therefore only
+say that the quantity of the poison soluble in physiological salt
+solution, even when the spiders are perfectly fresh and well nourished,
+is very insignificant. That the poison of the Russian tarantula is not
+soluble in physiological salt solution, is exceedingly improbable.
+Moreover, I have prepared alcoholic extracts and was unable to find them
+active. Since the Russian spider exceeds the Italian in size and in
+intensity of the bite, it seems very improbable to me that the
+pharmacological test of the Italian tarantula would yield essentially
+other results than those from the Russian species."
+
+To the AVICULAROIDEA belong the largest and most formidable appearing of
+the spiders and it is not strange that in the New World they have fallen
+heir to the bad reputation, as well as to the name of the tarantula of
+Europe. In this country they occur only in the South or in the far West,
+but occasionally living specimens are brought to our northern ports in
+shipments of bananas and other tropical produce, and are the source of
+much alarm. It should be mentioned, however, that the large spider most
+frequently found under such circumstances is not a tarantula at all, but
+one of the Heteropodidae, or giant crab-spiders, (fig. 8).
+
+[Illustration: 8. The giant crab-spider or banana spider (Heteropoda
+venatoria). Natural size. After Comstock.]
+
+In spite of their prominence and the fear which they arouse there are
+few accurate data regarding these American tarantulas. It has often been
+shown experimentally that they can kill small birds and mammals, though
+it is doubtful if these form the normal prey of any of the species, as
+has been claimed. There is no question but that the mere mechanical
+injury which they may inflict, and the consequent chances of secondary
+infection, justify, in part, their bad reputation. In addition to the
+injury from their bite, it is claimed that the body hairs of several of
+the South American species are readily detached and are urticating.
+
+Recently, Phisalix (1912) has made a study of the physiological effects
+of the venom of two Avicularoidea, _Phormictopus carcerides_ Pocock,
+from Haiti and _Cteniza sauvagei_ Rossi, from Corsica. The glands were
+removed aseptically and ground up with fine, sterilized sand in
+distilled water. The resultant liquid was somewhat viscid, colorless,
+and feebly alkaline. Injected into sparrows and mice the extract of
+_Phormictopus_ proved very actively poisonous, that from a single spider
+being sufficient to kill ten sparrows or twenty mice. It manifested
+itself first and, above all, as a narcotic, slightly lowering the
+temperature and paralyzing the respiration. Muscular and cardiac
+weakening, loss of general sensibility, and the disappearance of
+reflexes did not occur until near the end. The extract from _Cteniza_
+was less active and, curiously enough, the comparative effect on
+sparrows and on mice was just reversed.
+
+
+SPIDERS OF THE GENUS LATRODECTUS.--While most of the popular accounts of
+evil effects from the bites of spiders will not stand investigation, it
+is a significant fact that, the world over, the best authenticated
+records refer to a group of small and comparatively insignificant
+spiders belonging to the genus _Latrodectus_, of the family Theridiidae.
+The dread "Malmigniatte" of Corsica and South Europe, the "Karakurte" of
+southeastern Russia, the "Katipo" of New Zealand, the "Mena-vodi" and
+"Vancoho" of Madagascar, and our own _Latrodectus mactans_, all belong
+to this genus, and concerning all of these the most circumstantial
+accounts of their venomous nature are given. These accounts are not mere
+fantastic stories by uneducated natives but in many cases are reports
+from thoroughly trained medical men.
+
+The symptoms produced are general, rather than local. As summarized by
+Kobert (1901) from a study of twenty-two cases treated in 1888, in the
+Kherson (Russia) Government Hospital and Berislaw (Kherson) District
+Hospital the typical case, aside from complications, exhibits the
+following symptoms. The victim suddenly feels the bite, like the sting
+of a bee. Swelling of the barely reddened spot seldom follows. The
+shooting pains, which quickly set in, are not manifested at the point of
+injury but localized at the joints of the lower limb and in the region
+of the hip. The severity of the pain forces the victim to the hospital,
+in spite of the fact that they otherwise have a great abhorrence of it.
+The patient is unable to reach the hospital afoot, or, at least, not
+without help, for there is usually inability to walk. The patient, even
+if he has ridden, reaches the hospital covered with cold sweat and
+continues to perspire for a considerable period. His expression
+indicates great suffering. The respiration may be somewhat dyspnoeic,
+and a feeling of oppression in the region of the heart is common. There
+is great aversion to solid food, but increasing thirst for milk and tea.
+Retention of urine, and constipation occur. Cathartics and, at night,
+strong narcotics are desired. Warm baths give great relief. After three
+days, there is marked improvement and usually the patient is dismissed
+after the fifth. This summary of symptoms agrees well with other
+trustworthy records.
+
+It would seem, then, that Riley and Howard (1889), who discussed a
+number of accounts in the entomological literature, were fully justified
+in their statement that "It must be admitted that certain spiders of the
+genus _Latrodectus_ have the power to inflict poisonous bites, which may
+(probably exceptionally and depending upon exceptional conditions) bring
+about the death of a human being."
+
+And yet, until recently the evidence bearing on the question has been
+most conflicting. The eminent arachnologist, Lucas, (1843) states that
+he himself, had been repeatedly bitten by the Malmigniatte without any
+bad effects. Dr. Marx, in 1890, gave before the Entomological Society of
+Washington, an account of a series of experiments to determine whether
+the bite of _Latrodectus mactans_ is poisonous or not. He described the
+poison glands as remarkably small[A] and stated that he had introduced
+the poison in various ways into guinea-pigs and rabbits without
+obtaining any satisfactory results. Obviously, carefully conducted
+experiments with the supposed venom were needed and fortunately they
+have been carried out in the greatest detail by Kobert (1901).
+
+This investigator pointed out that there were two factors which might
+account for the discrepancies in the earlier experiments. In the first
+place, the poison of spiders, as of snakes, might be so exhausted after
+two or three bites that further bites, following directly, might be
+without visible effect. Secondly, the application of the poison by means
+of the bite, is exceedingly inexact, since even after the most careful
+selection of the point of application, the poison might in one instance
+enter a little vein or lymph vessel, and in another case fail to do so.
+Besides, there would always remain an incalculable and very large amount
+externally, in the nonabsorptive epithelium. While all of these factors
+enter into the question of the effect of the bite in specific instances,
+they must be as nearly as possible obviated in considering the question
+of whether the spiders really secrete a venom harmful to man.
+
+Kobert therefore sought to prepare extracts which would contain the
+active principles of the poison and which could be injected in definite
+quantities directly into the blood of the experimental animal. For this
+purpose various parts of the spiders were rubbed up in a mortar with
+distilled water, or physiological salt solution, allowed to stand for an
+hour, filtered, and then carefully washed, by adding water drop by drop
+for twenty-four hours. The filtrate and the wash-water were then united,
+well mixed and, if necessary, cleared by centrifuging or by exposure to
+cold. The mixture was again filtered, measured, and used, in part, for
+injection and, in part, for the determination of the organic materials.
+
+Such an extract was prepared from the cephalothoraces of eight dried
+specimens of the Russian _Latrodectus_ and three cubic centimeters of
+this, containing 4.29 mg. of organic material, were injected into the
+jugular vein of a cat weighing 2450 grams. The previously very active
+animal was paralyzed and lay in whatever position it was placed. The
+sensibility of the skin of the extremities and the rump was so reduced
+that there was no reaction from cutting or sticking. There quickly
+followed dyspnoea, convulsions, paralysis of the respiratory muscles
+and of the heart. In twenty-eight minutes the cat was dead, after having
+exhibited exactly the symptoms observed in severe cases of poisoning of
+man from the bite of this spider.
+
+These experiments were continued on cats, dogs, guinea pigs and various
+other animals. Not only extracts from the cephalothorax, but from other
+parts of the body, from newly hatched spiders, and from the eggs were
+used and all showed a similar virulence. Every effort was made to avoid
+sources of error and the experiments, conducted by such a recognized
+authority in the field of toxicology, must be accepted as conclusively
+showing that this spider and, presumably, other species of the genus
+_Latrodectus_ against which the clinical evidence is quite parallel,
+possess a poison which paralyzes the heart and central nervous system,
+with or without preliminary stimulus of the motor center. If the
+quantity of the poison which comes into direct contact with the blood is
+large, there may occur haemolysis and thrombosis of the vessels.
+
+On the other hand, check experiments were carried out, using similar
+extracts of many common European spiders of the genera _Tegenaria_,
+_Drassus_, _Agelena_, _Eucharia_ and _Argyroneta_, as well as the
+Russian tarantula, _Lycosa singoriensis_. In no other case was the
+effect on experimental animals comparable to the _Latrodectus_ extract.
+
+Kobert concludes that in its chemical nature the poison is neither an
+alkaloid, nor a glycoside, nor an acid, but a toxalbumen, or poisonous
+enzyme which is very similar to certain other animal poisons, notably
+that of the scorpion.
+
+[Illustration: 9. Latrodectus mactans; (_a_) female, x3; (_b_) venter
+of female; (_c_) dorsum of male. After Comstock.]
+
+The genus _Latrodectus_ is represented in the United States by at least
+two species, _L. mactans_ and _L. geometricus_. Concerning _L. mactans_
+there are very circumstantial accounts of serious injury and even death
+in man[B]. _Latrodectus mactans_ is coal black, marked with red or
+yellow or both. It has eight eyes, which are dissimilar in color and
+are distinctly in front of the middle of the thorax, the lateral eyes of
+each side widely separate. The tarsus of the fourth pair of legs has a
+number of curved setae in a single series. It has on the ventral side of
+its abdomen an hour-glass shaped spot. The full-grown female is about
+half an inch in length. Its globose abdomen is usually marked with one
+or more red spots dorsally along the middle line. The male is about half
+as long but has in addition to the dorsal spots, four pairs of stripes
+along the sides. Immature females resemble the male in coloring (fig.
+9).
+
+Regarding the distribution of _Latrodectus mactans_, Comstock states
+that: "Although it is essentially a Southern species, it occurs in
+Indiana, Ohio, Pennsylvania, New Hampshire, and doubtless other of the
+Northern States." _L. geometricus_ has been reported from California.
+
+
+OTHER VENOMOUS SPIDERS--While conclusive evidence regarding the venomous
+nature of spiders is meager and relates almost wholly to that of the
+genus _Latrodectus_, the group is a large one and we are not justified
+in dismissing arbitrarily, all accounts of injury from their bites.
+Several species stand out as especially needing more detailed
+investigation.
+
+_Chiracanthium nutrix_ is a common European species of the family
+Clubionidae, concerning which there is much conflicting testimony. Among
+the reports are two by distinguished scientists whose accounts of
+personal experiences cannot be ignored. A. Forel allowed a spider of
+this species to bite him and not only was the pain extreme, but the
+general symptoms were so severe that he had to be helped to his house.
+The distinguished arachnologist, Bertkau reports that he, himself, was
+bitten and that an extreme, burning pain spread almost instantaneously
+over the arm and into the breast. There were slight chills the same day
+and throbbing pain at the wound lasted for days. While this particular
+species is not found in the United States, there are two other
+representatives of the genus and it is possible that they possess the
+same properties. We are unaware of any direct experimental work on the
+poison.
+
+_Epeira diadema_, of Europe, belongs to a wholly different group, that
+of the orb-weavers, but has long been reputed venomous. Kobert was able
+to prepare from it an extract whose effects were very similar to that
+prepared from _Latrodectus_, though feebler in its action. Under
+ordinary circumstances this spider is unable to pierce the skin of man
+and though Kobert's results seem conclusive, the spider is little to be
+feared.
+
+_Phidippus audax_ (_P. tripunctatus_) is one of our largest Attids, or
+jumping spiders. The late Dr. O. Lugger describes a case of severe
+poisoning from the bite of this spider and though details are lacking,
+it is quite possible that this and other large species of the same
+group, which stalk their prey, may possess a more active poison than
+that of web-building species.
+
+
+SUMMARY--It is clearly established that our common spiders are not to be
+feared and that the stories regarding their virulence are almost wholly
+without foundation. On the other hand, the chances of secondary
+infection from the bites of some of the more powerful species are not to
+be ignored.
+
+Probably all species possess a toxin secreted by the poison gland,
+virulent for insects and other normal prey of the spiders, but with
+little or no effect on man.
+
+There are a very few species, notably of the genus _Latrodectus_, and
+possibly including the European _Chiracanthium nutrix_ and _Epeira
+diadema_, which possess, in addition, a toxalbumen derived from the
+general body tissue, which is of great virulence and may even cause
+death in man and the higher animals.
+
+[Illustration: 10. A whip-scorpion (Mastigoproctus giganteus). Half
+natural size. After Comstock.]
+
+
+THE PEDIPALPIDA OR WHIP-SCORPIONS
+
+The tailed whip-scorpions, belonging to the family Thelyphonidae, are
+represented in the United States by the giant whip-scorpion
+_Mastigoproctus giganteus_ (fig. 10), which is common in Florida, Texas
+and some other parts of the South. In Florida, it is locally known as
+the "grampus" or "mule-killer" and is very greatly feared. There is no
+evidence that these fears have any foundation, and Dr. Marx states that
+there is neither a poison gland nor a pore in the claw of the
+chelicera.
+
+
+THE SCORPIONIDA, OR TRUE SCORPIONS
+
+The true scorpions are widely distributed throughout warm countries and
+everywhere bear an evil reputation. According to Comstock (1912), about
+a score of species occur in the Southern United States. These are
+comparatively small forms but in the tropics members of this group may
+reach a length of seven or eight inches. They are pre-eminently
+predaceous forms, which lie hidden during the day and seek their prey by
+night.
+
+[Illustration: 11. A true scorpion. After Comstock.]
+
+The scorpions (fig. 11) possess large pedipalpi, terminated by strongly
+developed claws, or chelae. They may be distinguished from all other
+Arachnids by the fact that the distinctly segmented abdomen is divided
+into a broad basal region of seven segments and a terminal, slender,
+tail-like division of five distinct segments.
+
+The last segment of the abdomen, or telson, terminates in a
+ventrally-directed, sharp spine, and contains a pair of highly developed
+poison glands. These glands open by two small pores near the tip of the
+spine. Most of the species when running carry the tip of the abdomen
+bent upward over the back, and the prey, caught and held by the
+pedipalpi, is stung by inserting the spine of the telson and allowing it
+to remain for a time in the wound.
+
+The glands themselves have been studied in _Prionurus citrinus_ by
+Wilson (1904). He found that each gland is covered by a sheet of muscle
+on its mesal and dorsal aspects, which may be described as the
+_compressor muscle_. The muscle of each side is inserted by its edge
+along the ventral inner surface of the chitinous wall of the telson,
+close to the middle line, and by a broader insertion laterally. A layer
+of fine connective tissue completely envelops each gland and forms the
+basis upon which the secreting cells rest. The secreting epithelium is
+columnar; and apparently of three different types of cells.
+
+1. The most numerous have the appearance of mucous cells, resembling the
+goblet cells of columnar mucous membranes. The nucleus, surrounded by a
+small quantity of protoplasm staining with haematoxylin, lies close to
+the base of the cell.
+
+2. Cells present in considerable numbers, the peripheral portions of
+which are filled with very numerous fine granules, staining with acid
+dyes such as methyl orange.
+
+3. Cells few in number, filled with very large granules, or irregular
+masses of a substance staining with haematoxylin.
+
+The poison, according to Kobert (1893), is a limpid, acid-reacting
+fluid, soluble in water but insoluble in absolute alcohol and ether.
+There are few data relative to its chemical nature. Wilson (1901) states
+that a common Egyptian species, _Buthus quinquestriatus_, has a specific
+gravity of 1.092, and contains 20.3% of solids and 8.4% ash.
+
+The venom of different species appears to differ not only quantitatively
+but qualitatively. The effects of the bite of the smaller species of the
+Southern United States may be painful but there is no satisfactory
+evidence that it is ever fatal. On the other hand, certain tropical
+species are exceedingly virulent and cases of death of man from the bite
+are common.
+
+In the case of _Buthus quinquestriatus_, Wilson (1904) found the
+symptoms in animals to be hypersecretion, salivation and lachrymation,
+especially marked, convulsions followed by prolonged muscular spasm;
+death from asphyxia. The temperature shows a slight, rarely
+considerable, rise. Rapid and considerable increase of blood-pressure
+(observed in dogs) is followed by a gradual fall with slowing of the
+heart-beat. The coagulability of the blood is not affected.
+
+An interesting phase of Wilson's work was the experiments on desert
+mammals. The condition under which these animals exist must frequently
+bring them in contact with scorpions, and he found that they possess a
+degree of immunity to the venom sufficient at least to protect them from
+the fatal effects of the sting.
+
+As far as concerns its effect on man, Wilson found that much depended
+upon the age. As high as 60 per cent of the cases of children under
+five, resulted fatally. Caroroz (1865), states that in a Mexican state
+of 15,000 inhabitants, the scorpions were so abundant and so much feared
+that the authorities offered a bounty for their destruction. A result
+was a large number of fatalities, over two hundred per year. Most of the
+victims were children who had attempted to collect the scorpions.
+
+The treatment usually employed in the case of bites by the more
+poisonous forms is similar to that for the bite of venomous snakes.
+First, a tight ligature is applied above the wound so as to stop the
+flow of blood and lymph from that region. The wound is then freely
+excised and treated with a strong solution of permanganate of potash, or
+with lead and opium lotion.
+
+In recent years there have been many attempts to prepare an antivenom,
+or antiserum comparable to what has been used so effectively in the case
+of snake bites. The most promising of these is that of Todd (1909),
+produced by the immunization of suitable animals. This antivenom proved
+capable of neutralizing the venom when mixed _in vitro_ and also acts
+both prophylactically and curatively in animals. Employed curatively in
+man, it appears to have a very marked effect on the intense pain
+following the sting, and the evidence so far indicates that its prompt
+use greatly reduces the chance of fatal results.
+
+
+THE SOLPUGIDA, OR SOLPUGIDS
+
+The SOLPUGIDA are peculiar spider-like forms which are distinguished
+from nearly all other arachnids by the fact that they possess no true
+cephalothorax, the last two leg-bearing segments being distinct,
+resembling those of the abdomen in this respect. The first pair of legs
+is not used in locomotion but seemingly functions as a second pair of
+pedipalpi. Figure 12 illustrates the striking peculiarities of the
+group. They are primarily desert forms and occur in the warm zones of
+all countries. Of the two hundred or more species, Comstock lists twelve
+as occurring in our fauna. These occur primarily in the southwest.
+
+[Illustration: 12. A solpugid (Eremobates cinerea). After Comstock.]
+
+The Solpugida have long borne a bad reputation and, regarding virulence,
+have been classed with the scorpions. Among the effects of their bites
+have been described painful swelling, gangrene, loss of speech, cramps,
+delirium, unconsciousness and even death. Opposed to the numerous loose
+accounts of poisoning, there are a number of careful records by
+physicians and zoologists which indicate clearly that the effects are
+local and though they may be severe, they show not the slightest symptom
+of direct poisoning.
+
+More important in the consideration of the question is the fact that
+there are neither poison glands nor pores in the fangs for the exit of
+any poisonous secretion. This is the testimony of a number of prominent
+zoologists, among whom is Dr. A. Walter, who wrote to Kobert at length
+on the subject and whose conclusions are presented by him.
+
+However, it should be noted that the fangs are very powerful and are
+used in such a manner that they may inflict especially severe wounds.
+Thus, there may be more opportunity for secondary infection than is
+usual in the case of insect wounds.
+
+The treatment of the bite of the Solpugida is, therefore, a matter of
+preventing infection. The wound should be allowed to bleed freely and
+then washed out with a 1:3000 solution of corrosive sublimate, and, if
+severe, a wet dressing of this should be applied. If infection takes
+place, it should be treated in the usual manner, regardless of its
+origin.
+
+
+THE ACARINA, OR MITES AND TICKS
+
+A number of the parasitic Acarina evidently secrete a specific poison,
+presumably carried by the saliva, but in most cases its effect on man is
+insignificant. There is an abundant literature dealing with the
+poisonous effect of the bite of these forms, especially the ticks, but
+until recently it has been confused by failure to recognize that various
+species may transmit diseases of man, rather than produce injury through
+direct poisoning. We shall therefore discuss the Acarina more especially
+in subsequent chapters, dealing with parasitism and with disease
+transmission.
+
+Nevertheless, after the evidence is sifted, there can be no doubt that
+the bites of certain ticks may occasionally be followed by a direct
+poisoning, which may be either local or general in its effects. Nuttall
+(1908) was unable to determine the cause of the toxic effect, for, in
+_Argas persicus_, the species most often implicated, he failed to get
+the slightest local or general effect on experimental animals, from the
+injection of an emulsion prepared by crushing three of the ticks.
+
+It seems clearly established that the bite of certain ticks may cause a
+temporary paralysis, or even complete paralysis, involving the organs of
+respiration or the heart, and causing death. In 1912, Dr. I. U. Temple,
+of Pendleton, Oregon, reported several cases of what he called "acute
+ascending paralysis" associated with the occurrence of ticks on the head
+or the back of the neck. A typical severe case was that of a six year
+old child, who had retired in her usual normal health. The following
+morning upon arising she was unable to stand on her feet. She exhibited
+paralysis extending to the knees, slight temperature, no pain, sensory
+nerves normal, motor nerves completely paralyzed, reflexes absent. The
+following day the paralysis had extended to the upper limbs, and before
+night of the third day the nerves of the throat (hypoglossal) were
+affected. The thorax and larynx were involved, breathing was labored,
+she was unable to swallow liquids, phonation was impossible and she
+could only make low, guttural sounds. At this stage, two ticks, fully
+distended with blood, were found over the junction of the spinal column
+with the occipital bones in the hollow depression. They were removed by
+the application of undiluted creoline. Though the child's life was
+despaired of, by the following morning she was very much improved. By
+evening she was able to speak. The paralysis gradually receded,
+remaining longest in the feet, and at the end of one week the patient
+was able to go home.
+
+There was some doubt as to the exact species of tick implicated in the
+cases which Dr. Temple reported, although the evidence pointed strongly
+to _Dermacentor venustus_.[C] Somewhat later, Hadwen (1913) reported
+that "tick paralysis" occurs in British Columbia, where it affects not
+only man, but sheep and probably other animals. It is caused by the
+bites of _Dermacentor venustus_ and was experimentally produced in lambs
+and a dog (Hadwen and Nuttall, 1913). It is only when the tick begins to
+engorge or feed rapidly, some days after it has become attached, that
+its saliva produces pathogenic effects.
+
+Ulceration following tick bite is not uncommon. In many of the instances
+it is due to the file-like hypostome, with its recurved teeth, being
+left in the wound when the tick is forcibly pulled off.
+
+
+THE MYRIAPODA, OR CENTIPEDES AND MILLIPEDES
+
+The old class, Myriapoda includes the DIPLOPODA, or millipedes, and the
+CHILOPODA, or centipedes. The present tendency is to raise these groups
+to the rank of classes.
+
+
+The Diplopoda
+
+The DIPLOPODA, or millipedes (fig. 13), are characterized by the
+presence of two pairs of legs to a segment. The largest of our local
+myriapods belong to this group. They live in moist places, feeding
+primarily on decaying vegetable matter, though a few species
+occasionally attack growing plants.
+
+[Illustration: 13. A millipede. After Comstock.]
+
+The millipedes are inoffensive and harmless. _Julus terrestris_, and
+related species, when irritated pour out over the entire body a
+yellowish secretion which escapes from cutaneous glands. It is volatile,
+with a pungent odor, and Phisalix (1900) has shown that it is an active
+poison when injected into the blood of experimental animals. This,
+however, does not entitle them to be considered as poisonous arthropods,
+in the sense of this chapter, any more than the toad can be considered
+poisonous to man because it secretes a venom from its cutaneous glands.
+
+
+The Chilopoda
+
+[Illustration: 14. Two common centipedes.
+
+(_a_) Lithobius forficatus. After Comstock.
+
+(_b_) Scutigera forceps. Natural size; after Howard.]
+
+The CHILOPODA, or centipedes (fig. 14), unlike the millipedes, are
+predaceous forms, and possess well developed poison glands for killing
+their prey. These glands are at the base of the first pair of legs
+(fig. 15), which are bent forward so as to be used in holding their
+prey. The legs terminate in a powerful claw, at the tip of which is the
+outlet of the poison glands.
+
+The poison is a limpid, homogeneous, slightly acid fluid, which
+precipitates in distilled water. Briot (1904) extracted it from the
+glands of _Scolopendra morsitans_, a species common in central France,
+and found that it was actively venomous for the ordinary experimental
+animals. A rabbit of two kilograms weight received an injection of three
+cubic centimeters in the vein of the ear and died in a minute. A white
+rat, weighing forty-eight grams, received one and a half cubic
+centimeters in the hind leg. There was an almost immediate paralysis of
+the leg and marked necrosis of the tissues.
+
+[Illustration: 15. Mandible of Scolopendra cingulata showing venom
+gland. After Dubosq.]
+
+As for the effect on man, there is little foundation for the fear with
+which centipedes are regarded. Our native species produce, at most,
+local symptoms,--sometimes severe local pain and swelling,--but there is
+no authentic record of fatal results. In the tropics, some of the
+species attain a large size, _Scolopendra gigantea_ reaching a length of
+nearly a foot. These forms are justly feared, and there is good evidence
+that death sometimes, though rarely, results from their bite.
+
+One of the most careful accounts of death from the sting of the scorpion
+is that of Linnell, (1914), which relates to a comparatively small
+Malayan species, unfortunately undetermined. The patient, a coolie, aged
+twenty, was admitted to a hospital after having been stung two days
+previously on the left heel. For cure, the other coolies had made him
+eat the head of the scorpion. On admission, the patient complained of
+"things creeping all over the body". Temp. 102.8^o. On the fourth day he
+had paralysis of the legs, and on the fifth day motor paralysis to the
+umbilicus, sensation being unaltered. On the sixth day there was
+retention of the urine and on the ninth day (first test after third day)
+sugar was present. On the thirteenth day the patient became comatose,
+but could be roused to eat and drink. The temperature on the following
+day fell below 95^o and the patient was still comatose. Death fifteenth
+day.
+
+Examination of the spinal (lumbar) cord showed acute disseminated
+myelitis. In one part there was an acute destruction of the anterior
+horn and an infiltration of round cells. In another portion Clarke's
+column had been destroyed. The perivascular sheaths were crowded with
+small round cells and the meninges were congested. Some of the cells of
+the anterior horn were swollen and the nuclei eccentric; chromatolysis
+had occurred in many of them.
+
+As for treatment, Castellani and Chalmers (1910), recommend bathing the
+part well with a solution of ammonia (one in five, or one in ten). After
+bathing, apply a dressing of the same alkali or, if there is much
+swelling and redness, an ice-bag. If necessary, hypodermic injections of
+morphine may be given to relieve the pain. At a later period
+fomentations may be required to reduce the local inflammation.
+
+
+THE HEXAPODA OR TRUE INSECTS
+
+There are a number of HEXAPODA, or true insects, which are, in one way
+or another, poisonous to man. These belong primarily to the orders
+Hemiptera, or true bugs; Lepidoptera, or butterflies and moths (larval
+forms); Diptera, or flies; Coleoptera, or beetles; and Hymenoptera, or
+ants, bees, and wasps. There are various ways in which they may be
+poisonous.
+
+1. _Piercing_ or _biting_ forms may inject an irritating or poisonous
+saliva into the wound caused by their mouth-parts.
+
+2. _Stinging forms_ may inject a poison, from glands at the caudal end
+of the abdomen, into wounds produced by a specially modified ovipositer,
+the _sting_.
+
+3. _Nettling_ properties may be possessed by the hairs of the insect.
+
+4. _Vescicating_, or _poisonous blood plasma_, or _body fluids_ are
+known to exist in a large number of species and may, under exceptional
+circumstances, affect man.
+
+For convenience of discussion, we shall consider poisonous insects under
+these various headings. In this, as in the preceding discussion, no
+attempt will be made to give an exhaustive list of the poisonous forms.
+Typical instances will be selected and these will be chosen largely from
+North American species.
+
+
+PIERCING OR BITING INSECTS POISONOUS TO MAN
+
+
+HEMIPTERA
+
+Several families of the true bugs include forms which, while normally
+inoffensive, are capable of inflicting painful wounds on man. In these,
+as in all of the Hemiptera, the mouth-parts are modified to form an
+organ for piercing and sucking. This is well shown by the accompanying
+illustration (fig. 16).
+
+The upper lip, or _labrum_, is much reduced and immovable, the lower
+lip, or _labium_, is elongated to form a jointed sheath, within which
+the lance-like mandibles and maxillae are enclosed. The mandibles are
+more or less deeply serrate, depending on the species concerned.
+
+[Illustration: 16. Beak of hemipteron.]
+
+The poison is elaborated by the salivary glands, excepting, possibly, in
+_Belostoma_ where Locy is inclined to believe that it is secreted by the
+maxillary glands. The salivary glands of the Hemiptera have been the
+subject of much study but the most recent, comprehensive work has been
+done by Bugnion and Popoff, (1908 and 1910) to whose text the reader is
+referred for details.
+
+The Hemiptera have two pairs of salivary glands: the _primary gland_, of
+which the efferent duct leads to the salivary syringe, and the
+_accessory gland_, of which the very long and flexuous duct empties into
+the primary duct at its point of insertion. Thus, when one observes the
+isolated primary gland it appears as though it had efferent ducts
+inserted at the same point. In _Nepa_ and the _Fulgoridae_ there are two
+accessory glands and therefore apparently three ducts at the same point
+on the primary gland. The _ensemble_ differs greatly in appearance in
+different species but we shall show here Bugnion and Popoff's figure of
+the apparatus of _Notonecta maculata_, a species capable of inflicting a
+painful bite on man (fig. 17).
+
+[Illustration: 17. Salivary glands of Notonecta maculata. After Bugnion
+and Popoff.]
+
+[Illustration: 18. Pharyngeal syringe or salivary pump of Fulgora
+maculata. After Bugnion and Popoff.]
+
+[Illustration: 19. Heteroptera, (_a_) Melanolestes picipes; (_b_)
+Notonecta undulata; (_c_, _d_) Aradus robustus (_c_) adult, (_d_) nymph,
+much enlarged; (_e_) Arilus cristatus; (_f_) Belostoma americana; (_g_)
+Nabis (Coriscus) subcoleoptratus, enlarged; (_h_) Cimex lectularius,
+(_i_) Oeciacus vicarius, much enlarged; (_j_) Lyctocoris fitchii, much
+enlarged. After Lugger.]
+
+Accessory to the salivary apparatus there is on the ventral side of the
+head, underneath the pharynx, a peculiar organ which the Germans have
+called the "Wanzenspritze," or syringe. The accompanying figure of the
+structure in _Fulgora maculata_ (fig. 18) shows its relation to the
+ducts of the salivary glands and to the beak. It is made up of a
+dilatation forming the body of the pump, in which there is a chitinous
+piston. Attached to the piston is a strong retractor muscle. The
+function of the salivary pump is to suck up the saliva from the salivary
+ducts and to force it out through the beak.
+
+Of the Hemiptera reported as attacking man, we shall consider briefly
+the forms most frequently noted.
+
+
+The NOTONECTIDAE, or _back swimmers_, (fig. 19_b_) are small, aquatic
+bugs that differ from all others in that they always swim on their
+backs. They are predaceous; feeding on insects and other small forms.
+When handled carelessly they are able to inflict a painful bite, which
+is sometimes as severe as the sting of a bee. In fact, they are known in
+Germany as "Wasserbienen."
+
+
+The BELOSTOMATIDAE, or _giant water bugs_, (fig. 19_f_) include the
+largest living Hemiptera. They are attracted to lights and on account of
+the large numbers which swarm about the electric street lamps in some
+localities they have received the popular name "electric light bugs."
+Our largest representatives in the northern United States belong to the
+two genera _Belostoma_ and _Banacus_, distinguished from each other by
+the fact that _Belostoma_ has a groove on the under side of the femur of
+the front leg, for the reception of the tibia.
+
+The salivary glands of Belostoma were figured by Leidy (1847) and later
+were studied in more detail by Locy (1884). There are two pairs of the
+glands, those of one pair being long and extending back as far as the
+beginning of the abdomen, while the others are about one-fourth as long.
+They lie on either side of the oesophagus. On each side of the
+oesophagus there is a slender tube with a sigmoid swelling which may
+serve as a poison reservoir. In addition to this salivary system, there
+is a pair of very prominent glands on the ventral side of the head,
+opening just above the base of the beak. These Locy has called the
+"cephalic glands" and he suggests that they are the source of the
+poison. They are the homologues of the maxillary glands described for
+other Hemiptera, and it is by no means clear that they are concerned
+with the production of venom. It seems more probable that in
+_Belostoma_, as in other Hemiptera, it is produced by the salivary
+glands, though the question is an open one.
+
+The Belostomatidae feed not only on insects, but on small frogs, fish,
+salamanders and the like. Matheson (1907) has recorded the killing of a
+good-sized bird by _Belostoma americana_. A woodpecker, or flicker, was
+heard to utter cries of distress, and fluttered and fell from a tree. On
+examination it was found that a bug of this species had inserted its
+beak into the back part of the skull and was apparently busily engaged
+in sucking the blood or brains of the bird. Various species of
+_Belostoma_ have been cited as causing painful bites in man. We can
+testify from personal experience that the bite of _Belostoma americana_
+may almost immediately cause severe, shooting pains that may extend
+throughout the arm and that they may be felt for several days.
+
+[Illustration: 20. Reduvius (Opsicoetus) personatus. (x2).]
+
+Relief from the pain may be obtained by the use of dilute ammonia, or a
+menthol ointment. In the not uncommon case of secondary infection the
+usual treatment for that should be adopted.
+
+[Illustration: 21. (_a_) Reduvius personatus, nymph. Photograph by M. V.
+S.]
+
+The REDUVIIDAE, or _assassin-bugs_ are capable of inflicting very painful
+wounds, as most collectors of Hemiptera know to their sorrow. Some
+species are frequently to be found in houses and outhouses and Dr.
+Howard suggests that many of the stories of painful spider bites relate
+to the attack of these forms.
+
+[Illustration: 21. (_b_) Reduvius personatus, adult (x2) Photograph by
+M. V. S.]
+
+An interesting psychological study was afforded in the summer of 1899,
+by the "kissing-bug" scare which swept over the country. It was reported
+in the daily papers that a new and deadly bug had made its appearance,
+which had the unpleasant habit of choosing the lips or cheeks for its
+point of attack on man. So widespread were the stories regarding this
+supposedly new insect that station entomologists all over the country
+began to receive suspected specimens for identification. At Cornell
+there were received, among others, specimens of stone-flies, may-flies
+and even small moths, with inquiries as to whether they were
+"kissing-bugs."
+
+[Illustration: 22. Rasahus biguttatus. (x2). After Howard.]
+
+Dr. L. O. Howard has shown that the scare had its origin in newspaper
+reports of some instances of bites by either _Melanolestes picipes_
+(fig. 19a) or _Opsicoetes personatus_ (fig. 20), in the vicinity of
+Washington, D. C. He then discusses in considerable detail the more
+prominent of the Reduviidae which, with greater or less frequency pierce
+the skin of human beings. These are _Opsicoetes personatus_,
+_Melanolestes picipes_, _Coriscus subcoleoptratus_ (fig. 19_g_),
+_Rasahus thoracicus_, _Rasahus biguttatus_ (fig. 22), _Conorhinus
+sanguisugus_ (fig. 71), and _Melanolestes abdominalis_ (fig. 23).
+
+[Illustration: 23. Melanolestes abdominalis (x2). After Marlatt.]
+
+One of the most interesting of these species is _Reduvius personatus_,
+(= _Opsicoetus personatus_), which is popularly known as the "masked
+bed-bug hunter." It owes this name to the fact that the immature nymphs
+(fig. 21) have their bodies and legs completely covered by dust and
+lint, and that they are supposed to prey upon bed-bugs. LeConte is
+quoted by Howard as stating that "This species is remarkable for the
+intense pain caused by its bite. I do not know whether it ever willingly
+plunges its rostrum into any person, but when caught, or unskilfully
+handled it always stings. In this case the pain is almost equal to the
+bite of a snake, and the swelling and irritation which result from it
+will sometimes last for a week."
+
+A species which very commonly attacks man is _Conorhinus sanguisugus_,
+the so-called "big bed-bug" of the south and southern United States. It
+is frequently found in houses and is known to inflict an exceedingly
+painful bite. As in the case of a number of other predaceous Hemiptera,
+the salivary glands of these forms are highly developed. The effect of
+the bite on their prey and, as Marlatt has pointed out, the constant and
+uniform character of the symptoms in nearly all cases of bites in man,
+clearly indicate that their saliva contains a specific substance. No
+satisfactory studies of the secretions have been made. On the other
+hand, Dr. Howard is doubtless right in maintaining that the very serious
+results which sometimes follow the bite are due to the introduction of
+extraneous poison germs. This is borne out by the symptoms of most of
+the cases cited in literature and also by the fact that treatment with
+corrosive sublimate, locally applied to the wound, has yielded favorable
+results.
+
+
+OTHER HEMIPTERA REPORTED AS POISONOUS TO MAN--A large number of other
+Hemiptera have been reported as attacking man. Of these, there are
+several species of Lygaeidae, Coreidae, and Capsidae. Of the
+latter, _Lygus pratensis_, the tarnished plant-bug, is reported by
+Professor Crosby as sucking blood. _Orthotylus flavosparsus_ is another
+Capsid which has been implicated. _Empoasca mali_ and _Platymetopius
+acutus_ of the Jassidae have also been reported as having similar
+habits.
+
+Whenever the periodical cicada or "seventeen-year locust" becomes
+abundant, the newspapers contain accounts of serious results from its
+bites. The senior author has made scores of attempts to induce this
+species to bite and only once successfully. At that time the bite was in
+no wise more severe than a pin-prick. A student in our department
+reports a similar experience. There is no case on record which bears
+evidence of being worthy of any credence, whatsoever.
+
+Under the heading of poisonous Hemiptera we might consider the bed-bugs
+and the lice. These will be discussed later, as parasites and as
+carriers of disease, and therefore need only be mentioned here.
+
+
+DIPTERA
+
+Several species of blood-sucking Diptera undoubtedly secrete a saliva
+possessing poisonous properties. Chief among these are the Culicidae, or
+mosquitoes, and the Simuliidae, or black-flies. As we shall consider
+these forms in detail under the heading of parasitic species and
+insects transmitting disease, we shall discuss here only the poison of
+the mosquitoes.
+
+It is well known that mosquitoes, when they bite, inject into the wound
+a minute quantity of poison. The effect of this varies according to the
+species of mosquito and also depends very much on the susceptibility of
+the individual. Soon after the bite a sensation of itching is noticed
+and often a wheal, or eminence, is produced on the skin, which may
+increase to a considerable swelling. The scratching which is induced may
+cause a secondary infection and thus lead to serious results. Some
+people seem to acquire an immunity against the poison.
+
+The purpose of this irritating fluid may be, as Reaumur suggested, to
+prevent the coagulation of the blood and thus not only to cause it to
+flow freely when the insect bites but to prevent its rapid coagulation
+in the stomach. Obviously, it is not developed as a protective fluid,
+and its presence subjects the group to the additional handicap of the
+vengeance of man.
+
+[Illustration: 24. Diagram of a longitudinal section of a mosquito.]
+
+As to the origin of the poison, there has been little question, until
+recent years, that it was a secretion from the salivary glands.
+Macloskie (1888) showed that each gland is subdivided into three lobes,
+the middle of which differs from the others in having evenly granulated
+contents and staining more deeply than the others (fig. 24). This middle
+lobe he regarded as the source of the poison. Bruck, (1911), by the use
+of water, glycerine, chloroform, and other fluids, extracted from the
+bodies of a large number of mosquitoes a toxine which he calls
+_culicin_. This he assumes comes from the salivary glands. Animal
+experimentation showed that this extract possessed hemolytic powers.
+Inoculated into the experimenter's own skin it produced lesions which
+behaved exactly as do those of mosquito bites.
+
+Similarly, most writers on the subject have concurred with the view that
+the salivary glands are the source of the poison. However, recent work,
+especially that of Nuttall and Shipley (1903), and Schaudinn (1904), has
+shown that the evidence is by no means conclusive. Nuttall dissected out
+six sets (thirty-six acini) of glands from freshly killed _Culex
+pipiens_ and placed them in a drop of salt solution. The drop was
+allowed to dry, it being thought that the salt crystals would facilitate
+the grinding up of the glands with the end of a small glass rod, this
+being done under microscopic control. After grinding up, a small drop of
+water was added of the size of the original drop of saline, and an equal
+volume of human blood taken from the clean finger-tip was quickly mixed
+therewith, and the whole drawn up into a capillary tube. Clotting was
+not prevented and no hemolysis occurred. Salivary gland emulsion added
+to a dilute suspension of corpuscles did not lead to hemolysis. This
+experiment was repeated a number of times, with slight modification, but
+with similar results. The data obtained from the series "do not support
+the hypothesis that the salivary glands, at any rate in _Culex pipiens_,
+contain a substance which prevents coagulation."
+
+Much more detailed, and the more important experiments made along this
+line, are those of Schaudinn (1904). The results of these experiments
+were published in connection with a technical paper on the alternation
+of generations and of hosts in _Trypanosoma_ and _Spirochaeta_, and for
+this reason seem to have largely escaped the notice of entomologists.
+They are so suggestive that we shall refer to them in some detail.
+
+Schaudinn observed that the three oesophageal diverticula (commonly,
+but incorrectly, known as the "sucking stomach") (fig. 24) usually
+contain large bubbles of gas and in addition, he always found yeast
+cells. On the ground of numerous observations, Schaudinn was convinced
+that these yeast plants are normal and constant commensals of the
+insect. He regarded them as the cause of the gas bubbles to be found in
+diverticula. It was found that as the insect fed, from time to time the
+abdomen underwent convulsive contractions which resulted in the emptying
+of the oesophageal diverticula and the salivary glands through blood
+pressure.
+
+In order to test the supposed toxic action of the salivary glands,
+Schaudinn repeatedly introduced them under his skin and that of his
+assistant, in a drop of salt solution, and never obtained a suggestion
+of the irritation following a bite of the insect, even though the glands
+were carefully rubbed to fragments after their implantation. Like
+Nuttall, he failed to get satisfactory evidence that the secretion of
+the salivary glands retarded coagulation of the blood.
+
+He then carefully removed the oesophageal diverticula with their
+content of yeast and introduced them into an opening in the skin of the
+hand. Within a few seconds there was noticeable the characteristic
+itching irritation of the mosquito bite; and in a short time there
+appeared reddening and typical swelling. This was usually much more
+severe than after the usual mosquito bite, and the swelling persisted
+and itched longer. This was because by the ordinary bite of the mosquito
+most of the yeast cells are again sucked up, while in these experiments
+they remained in the wound. These experiments were repeated a number of
+times on himself, his assistant and others, and always with the same
+result. From them Schaudinn decided that the poisonous action of the
+mosquito bite is caused by an enzyme from a commensal fungus. These
+conclusions have not, as yet, been satisfactorily tested.
+
+Relief from the effect of the mosquito bite may be obtained by bathing
+the swellings with weak ammonia or, according to Howard, by using moist
+soap. The latter is to be rubbed gently on the puncture and is said to
+speedily allay the irritation. Howard also quotes from the _Journal of
+Tropical Medicine and Hygiene_ to the effect that a few drops of a
+solution of thirty to forty grains of iodine to an ounce of saponated
+petroleum rubbed into the mosquito bite, or wasp sting, allay the pain
+instantaneously.
+
+Methods of mosquito control will be discussed later, in considering
+these insects as parasites and as carriers of disease.
+
+
+STINGING INSECTS
+
+The stinging insects all belong to the order HYMENOPTERA. In a number of
+families of this group the ovipositor is modified to form a sting and is
+connected with poison-secreting glands. We shall consider the apparatus
+of the honey-bee and then make briefer reference to that of other forms.
+
+
+APIS MELLIFICA, THE HONEY BEE--The sting of the worker honey-bee is
+situated within a so-called sting chamber at the end of the abdomen.
+This chamber is produced by the infolding of the greatly reduced and
+modified eighth, ninth and tenth abdominal segments into the seventh.[D]
+From it the dart-like sting can be quickly exserted.
+
+The sting (fig. 25) is made up of a central shaft, ventro-laterad of
+which are the paired _lancets_, or darts, which are provided with sharp,
+recurved teeth. Still further laterad lie the paired whitish,
+finger-like _sting palpi_. Comparative morphological as well as
+embryological studies have clearly established that these three parts
+correspond to the three pairs of gonopophyses of the ovipositor of more
+generalized insects.
+
+[Illustration: 25. Sting of a honey bee. _Psn Sc_, base of acid poison
+gland; _B Gl_, alkaline poison gland; _Stn Plp_, sting palpi; _Sh B_,
+bulb of sting; _Sh A_, basal arm; _Lct_, lancets or darts; _Sh s_, shaft
+of sting. Modified from Snodgrass.]
+
+[Illustration: 26. Poison apparatus of a honey bee. Modified from
+Snodgrass.]
+
+An examination of the internal structures (fig. 26) reveals two distinct
+types of poison glands, the acid-secreting and the alkaline-secreting
+glands, and a prominent poison reservoir. In addition, there is a small
+pair of accessory structures which have been called lubricating glands,
+on account of the supposed function of their product. The acid-secreting
+gland empties into the distal end of the poison reservoir which in turn
+pours the secretion into the muscular bulb-like enlargement at the base
+of the shaft. The alkaline secreting gland empties into the bulb ventrad
+of the narrow neck of the reservoir.
+
+The poison is usually referred to as formic acid. That it is not so
+easily explained has been repeatedly shown and is evidenced by the
+presence of the two types of glands. Carlet maintains that the product
+of either gland is in itself innocent,--it is only when they are
+combined that the toxic properties appear.
+
+The most detailed study of the poison of the honey-bee is that of Josef
+Langer (1897), who in the course of his work used some 25,000 bees.
+Various methods of obtaining the active poison for experimental purposes
+were used. For obtaining the pure secretion, bees were held in the
+fingers and compressed until the sting was exserted, when a clear drop
+of the poison was visible at its tip. This was then taken up in a
+capillary tube or dilute solutions obtained by dipping the tip of the
+sting into a definite amount of distilled water.
+
+An aqueous solution of the poison was more readily obtained by pulling
+out the sting and poison sacs by means of forceps, and grinding them up
+in water. The somewhat clouded fluid was then filtered one or more
+times. For obtaining still greater quantities, advantage was taken of
+the fact that while alcohol coagulates the poison, the active principle
+remains soluble in water. Hence the stings with the annexed glands where
+collected in 96 per cent alcohol, after filtering off of the alcohol
+were dried at 40^o C., then rubbed to a fine powder and this was
+repeatedly extracted with water. Through filtering of this aqueous
+extract there was obtained a yellowish-brown fluid which produced the
+typical reactions, according to concentration of the poison.
+
+The freshly expelled drop of poison is limpid, of distinct acid
+reaction, tastes bitter and has a delicate aromatic odor. On
+evaporation, it leaves a sticky residue, which at 100 degrees becomes
+fissured, and suggests dried gum arabic. The poison is readily soluble
+in water and possesses a specific gravity of 1.1313. On drying at room
+temperature, it leaves a residue of 30 per cent, which has not lost in
+poisonous action or in solubility. In spite of extended experiments,
+Langer was unable to determine the nature of the active principle. He
+showed that it was not, as had been supposed, an albuminous body, but
+rather an organic base.
+
+The pure poison, or the two per cent aqueous solution, placed on the
+uninjured skin showed absolutely no irritating effect, though it
+produced a marked reaction on the mucus membrane of the nose or eye. A
+single drop of one-tenth per cent aqueous solution of the poison brought
+about a typical irritation in the conjunctiva of the rabbit's eye. On
+the other hand, the application of a drop of the poison, or its
+solution, to the slightest break in the skin, or by means of a needle
+piercing the skin, produced typical effects. There is produced a local
+necrosis, in the neighborhood of which there is infiltration of
+lymphocytes, oedema, and hyperaemia.
+
+The effect of the sting on man (fig. 27) is usually transitory but there
+are some individuals who are made sick for hours, by a single sting.
+Much depends, too, on the place struck. It is a common experience that
+an angry bee will attempt to reach the eye of its victim and a sting on
+the lid may result in severe and prolonged swelling. In the case of a
+man stung on the cheek, Legiehn observed complete aphonia and a breaking
+out of red blotches all over the body. A sting on the tongue has been
+known to cause such collateral oedema as to endanger life through
+suffocation. Cases of death of man from the attacks of bees are rare but
+are not unknown. Such results are usually from a number of stings but,
+rarely, death has been known to follow a single sting, entering a blood
+vessel of a particularly susceptible individual.
+
+[Illustration: Effect of bee stings. After Root.]
+
+It is clearly established that partial immunity from the effects of the
+poison may be acquired. By repeated injections of the venom, mice have
+been rendered capable of bearing doses that certainly would have killed
+them at first. It is a well-known fact that most bee-keepers become
+gradually hardened to the stings, so that the irritation and the
+swelling become less and less. Some individuals have found this immunity
+a temporary one, to be reacquired each season. A striking case of
+acquired immunity is related by the Roots in their "A B C and X Y Z of
+Bee Culture." The evidence in the case is so clear that it should be
+made more widely available and hence we quote it here.
+
+A young man who was determined to become a bee-keeper, was so
+susceptible to the poison that he was most seriously affected by a
+single sting, his body breaking out with red blotches, breathing growing
+difficult, and his heart action being painfully accelerated. "We finally
+suggested taking a live bee and pressing it on the back of his hand
+until it merely pierced his skin with the sting, then immediately
+brushing off both bee and sting. This was done and since no serious
+effect followed, it was repeated inside of four or five days. This was
+continued for some three or four weeks, when the patient began to have a
+sort of itching sensation all over his body. The hypodermic injections
+of bee-sting poison were then discontinued. At the end of a month they
+were repeated at intervals of four or five days. Again, after two or
+three weeks the itching sensation came on, but it was less pronounced.
+The patient was given a rest of about a month, when the doses were
+repeated as before." By this course of treatment the young man became so
+thoroughly immunized that neither unpleasant results nor swelling
+followed the attacks of the insects and he is able to handle bees with
+the same freedom that any experienced bee-keeper does.
+
+In an interesting article in the _Entomological News_ for November,
+1914, J. H. Lovell calls attention to the fact that "There has been a
+widespread belief among apiarists that a beekeeper will receive more
+stings when dressed in black than when wearing white clothing. A large
+amount of evidence has been published in the various bee journals
+showing beyond question that honey-bees under certain conditions
+discriminate against black. A few instances may be cited in
+illustration. Of a flock of twelve chickens running in a bee-yard seven
+black ones were stung to death, while five light colored ones escaped
+uninjured. A white dog ran among the bee-hives without attracting much
+attention, while at the same time a black dog was furiously assailed by
+the bees. Mr. J. D. Byer, a prominent Canadian beekeeper, relates that a
+black and white cow, tethered about forty feet from an apiary, was one
+afternoon attacked and badly stung by bees. On examination it was found
+that the black spots had five or six stings to one on the white. All
+noticed this fact, although no one was able to offer any explanation. A
+white horse is in much less danger of being stung, when driven near an
+apiary, than a black one. It has, indeed, been observed repeatedly that
+domestic animals of all kinds, if wholly or partially black, are much
+more liable to be attacked by bees, if they wander among the hives, than
+those which are entirely white."
+
+In order to test the matter experimentally, the following series of
+experiments was performed. In the language of the investigator:
+
+"On a clear, warm day in August I dressed wholly in white with the
+exception of a black veil. Midway on the sleeve of my right arm there
+was sewed a band of black cloth ten inches wide. I then entered the
+bee-yard and, removing the cover from one of the hives, lifted a piece
+of comb with both hands and gently shook it. Instantly many of the bees
+flew to the black band, which they continued to attack as long as they
+were disturbed. Not a single bee attempted to sting the left sleeve,
+which was of course entirely white, and very few even alighted upon it."
+
+"This experiment was repeated a second, third and fourth time; in each
+instance with similar results. I estimated the number of bees on the
+band of black cloth at various moments was from thirty to forty; it was
+evident from their behavior that they were extremely irritable. To the
+left white sleeve and other portions of my clothing they paid very
+little attention; but the black veil was very frequently attacked."
+
+"A few days later the experiments were repeated, but the band of black
+cloth, ten inches wide, was sewed around my left arm instead of around
+the right arm as before. When the bees were disturbed, after the hive
+cover had been removed, they fiercely attacked the band of black cloth
+as in the previous experiences; but the right white sleeve and the white
+suit were scarcely noticed. At one time a part of the black cloth was
+almost literally covered with furiously stinging bees, and the black
+veil was assailed by hundreds. The bees behaved in a similar manner when
+a second hive on the opposite side of the apiary was opened."
+
+"A white veil which had been procured for this purpose, was next
+substituted for the black veil. The result was most surprising, for,
+whereas in the previous experiments hundreds of bees had attacked the
+black veil, so few flew against the white veil as to cause me no
+inconvenience. Undoubtedly beekeepers will find it greatly to their
+advantage to wear white clothing when working among their colonies of
+bees and manipulating the frames of the hives."
+
+When a honey-bee stings, the tip of the abdomen, with the entire sting
+apparatus, is torn off and remains in the wound. Here the muscles
+continue to contract, for some minutes, forcing the barbs deeper and
+deeper into the skin, and forcing out additional poison from the
+reservoir.
+
+Treatment, therefore, first consists in removing the sting without
+squeezing out additional poison. This is accomplished by lifting and
+scraping it out with a knife-blade or the fingernail instead of grasping
+and pulling it out. Local application of alkalines, such as weak
+ammonia, are often recommended on the assumption that the poison is an
+acid to be neutralized on this manner, but these are of little or no
+avail. They should certainly not be rubbed in, as that would only
+accelerate the absorption of the poison. The use of cloths wrung out in
+hot water and applied as hot as can be borne, affords much relief in the
+case of severe stings. The application of wet clay, or of the end of a
+freshly cut potato is sometimes helpful.
+
+In extreme cases, where there is great susceptibility, or where there
+may have been many stings, a physician should be called. He may find
+strychnine injections or other treatment necessary, if general symptoms
+develop.
+
+[Illustration: 28. The poison apparatus of Formica. Wheeler, after
+Forel.]
+
+
+OTHER STINGING FORMS--Of the five thousand, or more, species of bees,
+most possess a sting and poison apparatus and some of the larger forms
+are capable of inflicting a much more painful sting than that of the
+common honey-bee. In fact, some, like the bumble bees, possess the
+advantage that they do not lose the sting from once using it, but are
+capable of driving it in repeatedly. In the tropics there are found many
+species of stingless bees but these are noted for their united efforts
+to drive away intruders by biting. Certain species possess a very
+irritating saliva which they inject into the wounds.
+
+The ants are not ordinarily regarded as worthy of consideration under
+the heading of "stinging insects" but as a matter of fact, most of them
+possess well developed stings and some of them, especially in the
+tropics, are very justly feared. Even those which lack the sting possess
+well-developed poison glands and the parts of the entire stinging
+apparatus, in so far as it is developed in the various species, may
+readily be homologized with those of the honey-bee.
+
+The ants lacking a sting are those of the subfamily CAMPONOTINAE, which
+includes the largest of our local species. It is an interesting fact
+that some of these species possess the largest poison glands and
+reservoir (fig. 28) and it is found that when they attack an enemy they
+bring the tip of the abdomen forward and spray the poison in such a way
+that it is introduced into the wound made by the powerful mandibles.
+
+[Illustration: 29. A harmless, but much feared larva, the "tomato worm."
+Natural size. Photograph by M. V. S.]
+
+More feared than any of the other Hymenoptera are the hornets and wasps.
+Of these there are many species, some of which attain a large size and
+are truly formidable. Phisalix (1897), has made a study of the venom of
+the common hornet and finds that, like the poison of the honey-bee, it
+is neither an albuminoid nor an alkaloid. Its toxic properties are
+destroyed at 120^o C. Phisalix also says that the venom is soluble in
+alcohol. If this be true, it differs in this respect from that of the
+bee. An interesting phase of the work of Phisalix is that several of her
+experiments go to show that the venom of hornets acts as a vaccine
+against that of vipers.
+
+
+NETTLING INSECTS
+
+So far, we have considered insects which possess poison glands connected
+with the mouth-parts or a special sting and which actively inject their
+poison into man. There remain to be considered those insects which
+possess poisonous hairs or body fluids which, under favorable
+circumstances, may act as poisons. To the first of these belong
+primarily the larvae of certain Lepidoptera.
+
+
+LEPIDOPTERA
+
+[Illustration: 30. Another innocent but much maligned caterpillar, the
+larva of the Regal moth. Photograph by M. V. S.]
+
+When we consider the reputedly poisonous larvae of moths and butterflies,
+one of the first things to impress us is that we cannot judge by mere
+appearance. Various species of Sphingid, or hawk-moth larvae, bear at the
+end of the body a chitinous horn, which is often referred to as a
+"sting" and regarded as capable of inflicting dangerous wounds. It would
+seem unnecessary to refer to this absurd belief if it were not that each
+summer the newspapers contain supposed accounts of injury from the
+"tomato worm" (fig. 29) and others of this group. The grotesque, spiny
+larva (fig. 30) of one of our largest moths, _Citheronia regalis_ is
+much feared though perfectly harmless, and similar instances could be
+multiplied.
+
+[Illustration: 31. The flannel moth (Lagoa crispata). (_a_) Poisonous
+larva.]
+
+[Illustration: 31. (_b_) Adult. Enlarged. Photographs by M. V. S.]
+
+But if the larvae are often misjudged on account of their ferocious
+appearance, the reverse may be true. A group of most innocent looking
+and attractive caterpillars is that of the flannel-moth larvae, of which
+_Lagoa crispata_ may be taken as an example. Its larva (fig. 31) has a
+very short and thick body, which is fleshy and completely covered and
+hidden by long silken hairs of a tawny or brown color, giving a convex
+form to the upper side. Interspersed among these long hairs are
+numerous short spines connected with underlying hypodermal poison
+glands. These hairs are capable of producing a marked nettling effect
+when they come in contact with the skin. This species is found in our
+Atlantic and Southern States. Satisfactory studies of its poisonous
+hairs and their glands have not yet been made.
+
+[Illustration: 32 The poisonous saddle back caterpillar. Empretia
+(Sibine) stimulea. Photograph by M. V. S.]
+
+[Illustration: 33_a_. Io moth larvae on willow. Photograph by M. V. S.]
+
+_Sibine stimulea (Empretia stimulea)_, or the saddle-back caterpillar
+(fig. 32), is another which possesses nettling hairs. This species
+belongs to the group of Eucleidae, or slug caterpillars. It can be
+readily recognized by its flattened form, lateral, bristling spines and
+by the large green patch on the back resembling a saddle-cloth, while
+the saddle is represented by an oval, purplish-brown spot. The small
+spines are venomous and affect some persons very painfully. The larva
+feeds on the leaves of a large variety of forest trees and also on
+cherry, plum, and even corn leaves. It is to be found throughout the
+Eastern and Southern United States.
+
+[Illustration: 33_b_. Io moth. Full grown larva. Photograph by M. V. S.]
+
+[Illustration: 34. Io moth. Adult. Photograph by M. V. S.]
+
+_Automeris io_ is the best known of the nettling caterpillars. It is the
+larva of the Io moth, one of the Saturniidae. The mature caterpillar,
+(fig. 33), which reaches a length of two and one-half inches, is of a
+beautiful pale green with sublateral stripes of cream and red color and
+a few black spines among the green ones. The green radiating spines give
+the body a mossy appearance. They are tipped with a slender chitinous
+hair whose tip is readily broken off in the skin and whose poisonous
+content causes great irritation. Some individuals are very susceptible
+to the poison, while others are able to handle the larvae freely without
+any discomfort. The larvae feed on a wide range of food plants. They are
+most commonly encountered on corn and on willow, because of the
+opportunities for coming in contact with them.
+
+[Illustration: 35. Larva of brown-tail moth. (Natural size). Photograph
+by M. V. S.]
+
+The larvae of the brown-tail moth (_Euproctis chrysorrhoea_) (fig. 35
+and 36), where they occur in this country, are, on account of their
+great numbers, the most serious of all poisonous caterpillars. It is not
+necessary here, to go into details regarding the introduction of this
+species from Europe into the New England States. This is all available
+in the literature from the United States Bureau of Entomology and from
+that of the various states which are fighting the species. Suffice to
+say, there is every prospect that the pest will continue to spread
+throughout the Eastern United States and Canada and that wherever it
+goes it will prove a direct pest to man as well as to his plants.
+
+Very soon after the introduction of the species there occurred in the
+region where it had gained a foothold, a mysterious dermatitis of man.
+The breaking out which usually occurred on the neck or other exposed
+part of the body was always accompanied by an intense itching. It was
+soon found that this dermatitis was caused by certain short, barbed
+hairs of the brown-tail caterpillars and that not only the caterpillars
+but their cocoons and even the adult female moths might harbor these
+nettling hairs and thus give rise to the irritation. In many cases the
+hairs were wafted to clothing on the line and when this was worn it
+might cause the same trouble. Still worse, it was found that very
+serious internal injury was often caused by breathing or swallowing the
+poisonous hairs.
+
+[Illustration: 36. Browntail moths. One male and two females. Photograph
+by M. V. S.]
+
+The earlier studies seemed to indicate that the irritation was purely
+mechanical in origin, the result of the minute barbed hairs working into
+the skin in large numbers. Subsequently, however, Dr. Tyzzer (1907)
+demonstrated beyond question that the trouble was due to a poison
+contained in the hairs. In the first place, it is only the peculiar
+short barbed hairs which will produce the dermatitis when rubbed on the
+skin, although most of the other hairs are sharply barbed. Moreover, it
+was found that in various ways the nettling properties could be
+destroyed without modifying the structure of the hairs. This was
+accomplished by baking for one hour at 110^o C, by warming to 60^o C in
+distilled water, or by soaking in one per cent. or in one-tenth per
+cent. of potassium hydrate or sodium hydrate. The most significant part
+of his work was the demonstration of the fact that if the nettling
+hairs are mingled with blood, they immediately produce a change in the
+red corpuscles. These at once become coarsely crenated, and the roleaux
+are broken up in the vicinity of the hair (fig. 37_b_). The corpuscles
+decrease in size, the coarse crenations are transformed into slender
+spines which rapidly disappear, leaving the corpuscles in the form of
+spheres, the light refraction of which contrasts them sharply with the
+normal corpuscles. The reaction always begins at the basal sharp point
+of the hair. It could not be produced by purely mechanical means, such
+as the mingling of minute particles of glass wool, the barbed hairs of a
+tussock moth, or the other coarser hairs of the brown-tail, with the
+blood.
+
+[Illustration: 37. (_a_) Ordinary hairs and three poison hairs of
+subdorsal and lateral tubercles of the larva of the browntail moth.
+Drawing by Miss Kephart.]
+
+The question of the source of the poison has been studied in our
+laboratory by Miss Cornelia Kephart. She first confirmed Dr. Tyzzer's
+general results and then studied carefully fixed specimens of the larvae
+to determine the distribution of the hairs and their relation to the
+underlying tissues.
+
+[Illustration: 37. (_b_) Effect of the poison on the blood corpuscles of
+man. After Tyzzer.]
+
+The poison hairs (fig. 37), are found on the subdorsal and lateral
+tubercles (fig. 38), in bunches of from three to twelve on the minute
+papillae with which the tubercles are thickly covered. The underlying
+hypodermis is very greatly thickened, the cells being three or four
+times the length of the ordinary hypodermal cells and being closely
+crowded together. Instead of a pore canal through the cuticula for each
+individual hair, there is a single pore for each papillae on a tubercle,
+all the hairs of the papilla being connected with the underlying cells
+through the same pore canal, (figs. 39 and 40).
+
+[Illustration: 38. Cross section of the larva of the browntail moth
+showing the tubercles bearing the poison hairs. Drawing by Miss
+Kephart.]
+
+The hypodermis of this region is of two distinct types of cells. First,
+there is a group of slender fusiform cells, one for each poison hair on
+the papilla, which are the trichogen, or hair-formative cells. They are
+crowded to one side and towards the basement membrane by a series of
+much larger, and more prominent cells (fig. 40), of which there is a
+single one for each papilla. These larger cells have a granular
+protoplasm with large nuclei and are obviously actively secreting. They
+are so characteristic in appearance as to leave no question but that
+they are the true poison glands.
+
+[Illustration: 39. Epithelium underlying poison hairs of the larva of
+the browntail moth. Drawing by Miss Kephart.]
+
+Poisonous larvae of many other species have been reported from Europe and
+especially from the tropics but the above-mentioned species are the more
+important of those occurring in the United States and will serve as
+types. It should be noted in this connection that through some curious
+misunderstanding Goeldi (1913) has featured the larva of _Orgyia
+leucostigma_, the white-marked tussock moth, as the most important of
+the poisonous caterpillars of this country. Though there are occasional
+reports of irritation from its hairs such cases are rare and there is no
+evidence that there is any poison present. Indeed, subcutaneous
+implantation of the hairs leads to no poisoning, but merely to temporary
+irritation.
+
+[Illustration: 40. Same as figure 39, on larger scale.]
+
+Occasionally, the hairs of certain species of caterpillars find
+lodgement in the conjunctiva, cornea, or iris of the eye of man and give
+rise to the condition known as _opthalmia nodosa_. The essential feature
+of this trouble is a nodular conjunctivitis which simulates tuberculosis
+of the conjunctiva and hence has been called _pseudo-tubercular_. It may
+be distinguished microscopically by the presence of the hairs.
+
+[Illustration: 41. (_a_) Nodular conjunctivitis in the eye of a child.
+De Schweinitz and Shumway.]
+
+Numerous cases of opthalmia nodosa are on record. Of those from this
+country, one of the most interesting is reported by de Schweinitz and
+Shumway (1904). It is that of a child of fifteen years whose eye had
+become inflamed owing to the presence of some foreign body. Downward and
+inward on the bulbar conjunctiva were a number of flattened,
+grayish-yellow nodules, between which was a marked congestion of the
+conjunctival and episcleral vessels (fig. 41_a_). Twenty-seven nodules
+could be differentiated, those directly in the center of the collection
+being somewhat confluent and assuming a crescentic and circular
+appearance. The nodules were excised and, on sectioning, were found to
+be composed of a layer of spindle cells and round cells, outside of
+which the tissue was condensed into a capsule. The interior consisted of
+epithelioid cells, between which was a considerable intercellular
+substance. Directly in the center of a certain number of nodules was
+found the section of a hair (fig. 41_b_). The evidence indicated that
+the injury had resulted from playing with caterpillars of one of the
+Arctiid moths, _Spilosoma virginica_. Other reported cases have been
+caused by the hairs of larvae of _Lasiocampa rubi_, _L. pini_,
+_Porthetria dispar_, _Psilura monacha_ and _Cnethocampa processionea_.
+
+[Illustration: 41_b_. Section through one of the nodules showing the
+caterpillar hair. De Schweinitz and Shumway.]
+
+
+RELIEF FROM POISONING BY NETTLING LARVAE--The irritation from nettling
+larvae is often severe and, especially in regions where the brown-tail
+abounds, inquiries as to treatment arise. In general, it may be said
+that cooling lotions afford relief, and that scratching, with the
+possibilities of secondary infection, should be avoided, in so far as
+possible.
+
+Among the remedies usually at hand, weak solutions of ammonia, or a
+paste of ordinary baking soda are helpful. Castellani and Chalmers
+recommend cleaning away the hairs by bathing the region with an alkaline
+lotion, such as two per cent solution of bicarbonate of soda, and then
+applying an ointment of ichthyol (10%).
+
+In the brown-tail district, there are many proprietary remedies of which
+the best ones are essentially the following, as recommended by Kirkland
+(1907):
+
+    Carbolic acid  1/2 drachm.
+    Zinc oxide     1/2 oz.
+    Lime water       8 oz.
+
+Shake thoroughly and rub well into the affected parts.
+
+In some cases, and especially where there is danger of secondary
+infection, the use of a weak solution of creoline (one teaspoonful to a
+quart of water), is to be advised.
+
+
+VESCICATING INSECTS AND THOSE POSSESSING OTHER POISONS IN THEIR BLOOD
+PLASMA
+
+We have seen that certain forms, for example, the poisonous spiders, not
+only secrete a toxine in their poison glands, but that such a substance
+may be extracted from other parts of their body, or even their eggs.
+There are many insects which likewise possess a poisonous blood plasma.
+Such forms have been well designated by Taschenberg as _cryptotoxic_
+([Greek: kryptos] = hidden). We shall consider a few representative
+forms.
+
+[Illustration: 42_a_. Blister beetle.]
+
+[Illustration: 42_b_. An American blister beetle. Meloe angusticollis.
+Photograph by M. V. S.]
+
+
+THE BLISTER BEETLES--Foremost among the cryptotoxic insects are the
+_Meloidae_ or "blister beetles," to which the well-known "Spanish fly"
+(fig. 42_a_), formerly very generally used in medical practice, belongs.
+The vescicating property is due to the presence in the blood plasma of a
+peculiar, volatile, crystalline substance known as _cantharidin_, which
+is especially abundant in the reproductive organs of the beetle.
+According to Kobert, the amount of this varies in different species from
+.4 or .5% to 2.57% of the dry weight of the beetle.
+
+While blister beetles have been especially used for external
+application, they are also at times used internally as a stimulant and a
+diuretic. The powder or extract was formerly much in vogue as an
+aphrodisiac, and formed the essential constituent of various philters,
+or "love powders". It is now known that its effects on the reproductive
+organs appear primarily after the kidneys have been affected to such an
+extent as to endanger life, and that many cases of fatal poison have
+been due to its ignorant use.
+
+There are many cases on record of poisoning and death due to internal
+use, and in some instances from merely external application. There are
+not rarely cases of poisoning of cattle from feeding on herbage bearing
+a large number of the beetles and authentic cases are known of human
+beings who have been poisoned by eating the flesh of such cattle. Kobert
+states that the beetles are not poisonous to birds but that the flesh of
+birds which have fed on them is poisonous to man, and that if the flesh
+of chickens or frogs which have fed on the cantharidin be fed to cats it
+causes in them the same symptoms as does the cantharidin.
+
+Treatment of cases of cantharidin poison is a matter for a skilled
+physician. Until he can be obtained, emetics should be administered and
+these should be followed by white of egg in water. Oils should be
+avoided, as they hasten the absorption of the poison.
+
+
+OTHER CRYPTOTOXIC INSECTS--Though the blister beetles are the best known
+of the insects with poisonous blood plasma, various others have been
+reported and we shall refer to a few of the best authenticated.
+
+One of the most famous is the Chrysomelid beetle, _Diamphidia simplex_,
+the body fluids of whose larvae are used by certain South African bushmen
+as an arrow poison. Its action is due to the presence of a toxalbumin
+which exerts a haemolytic action on the blood, and produces inflammation
+of the subcutaneous connective tissue and mucous membranes. Death
+results from general paralysis. Krause (1907) has surmised that the
+active principle may be a bacterial toxin arising from decomposition of
+the tissues of the larva, but he presents no support of this view and it
+is opposed by all the available evidence.
+
+In China, a bug, _Heuchis sanguinea_, belonging to the family Cicadidae,
+is used like the Meloidae, to produce blistering, and often causes
+poisoning. It has been assumed that its vescicating properties are due
+to cantharidin, but the presence of this substance has not been
+demonstrated.
+
+Certain Aphididae contain a strongly irritating substance which produces,
+not merely on mucous membranes but on outer skin, a characteristic
+inflammation.
+
+It has been frequently reported that the larvae of the European cabbage
+butterfly, _Pieris brassicae_, accidentally eaten by cows, horses, ducks,
+and other domestic animals, cause severe colic, attempts to vomit,
+paralysis of the hind legs, salivation, and stomatitis. On _postmortem_
+there are to be found haemorrhagic gastro-enteritis, splenitis, and
+nephritis. Kobert has recently investigated the subject and has found a
+poisonous substance in the blood of not only the larvae but also the
+pupae.
+
+
+FOOTNOTES:
+
+[A] This is diametrically opposed to the findings of Bordas (1905) in
+the case of the European _Latrodectus 13-guttatus_, whose glands are
+"much larger than those of other spiders." From a considerable
+comparative study, we should also unhesitatingly make this statement
+regarding the glands of our American species, _L. mactans_.
+
+[B] Dr. E. H. Coleman (Kellogg, 1915) has demonstrated its virulence by
+a series of experiments comparable with those of Kobert.
+
+[C] According to Stiles, the species occurring in the Northwest which is
+commonly identified as _D. venustus_ should be called _D. andersoni_
+(see footnote, chapter 12).
+
+[D] It should be remembered that in all the higher Hymenoptera the first
+abdominal segment is fused with the thorax and that what is apparently
+the sixth segment is, in reality, the seventh.
+
+
+
+
+CHAPTER III
+
+PARASITIC ARTHROPODA AFFECTING MAN
+
+
+The relation of insects to man as simple parasites has long been
+studied, and until very recent years the bulk of the literature of
+medical entomology referred to this phase of the subject. This is now
+completely overshadowed by the fact that so many of these parasitic
+forms are more than simple parasites, they are transmitters of other
+microscopic parasites which are pathogenic to man. Yet the importance of
+insects as parasites still remains and must be considered in a
+discussion of the relation of insects to the health of man. In taking up
+the subject we shall first consider some general features of the
+phenomenon of animal parasitism.
+
+Parasitism is an adaptation which has originated very often among living
+organisms and in widely separated groups. It would seem simple to define
+what is meant by a "parasite" but, in reality, the term is not easily
+limited. It is often stated that a parasite is "An organism which lives
+at the expense of another," but this definition is applicable to a
+predatory species or, in its broadest sense, to all organisms. For our
+purpose we may say with Braun: "A parasite is an organism which, for the
+purpose of obtaining food, takes up its abode, temporarily or
+permanently, on or within another living organism".
+
+Thus, parasitism is a phase of the broad biological phenomenon of
+_symbiosis_, or living together of organisms. It is distinguished from
+_mutualism_, or symbiosis in the narrow sense, by the fact that only one
+party to the arrangement obtains any advantage, while the other is to a
+greater or less extent injured.
+
+Of parasites we may distinguish on the basis of their location on or in
+the host, _ecto-parasites_, which live outside of the body; and
+_endo-parasites_, which live within the body. On account of their method
+of breathing the parasitic arthropods belong almost exclusively to the
+first of these groups.
+
+On the basis of relation to their host, we find _temporary parasites_,
+those which seek the host only occasionally, to obtain food; and the
+_stationary_ or _permanent_ parasites which, at least during certain
+stages, do not leave their host.
+
+_Facultative parasites_ are forms which are not normally parasitic, but
+which, when accidentally ingested, or otherwise brought into the body,
+are able to exist for a greater or less period of time in their unusual
+environment. These are generally called in the medical literature
+"pseudoparasites" but the term is an unfortunate one.
+
+We shall now take up the different groups of arthropods, discussing the
+more important of the parasitic forms attacking man. The systematic
+relationship of these forms, and key for determining important species
+will be found in Chapter XII.
+
+
+ACARINA OR MITES
+
+The ACARINA, or _mites_, form a fairly natural group of arachnids,
+characterized, in general, by a sac-like, unsegmented body which is
+generally fused with the cephalothorax. The mouth-parts have been united
+to form a beak or rostrum.
+
+The representatives of this group undergo a marked metamorphosis.
+Commonly, the larvae on hatching from the egg, possess but three pairs of
+legs, and hence are called _hexapod larvae_. After a molt, they transform
+into nymphs which, like the adult, have four pairs of legs and are
+called _octopod nymphs_. These after a period of growth, molt one or
+more times and, acquiring external sexual organs, become adult.
+
+Most of the mites are free-living, but there are many parasitic species
+and as these have originated in widely separated families, the Acarina
+form an especially favorable group for study of the origin of
+parasitism. Such a study has been made by Ewing (1911), who has reached
+the following conclusions:
+
+"We have strong evidence indicating that the parasitic habit has
+originated independently at least eleven times in the phylogeny of the
+Ararina. Among the zoophagous parasites, the parasitic habit has been
+developed from three different types of free-living Acarina: (a)
+predaceous forms, (b) scavengers, (c) forms living upon the juices of
+plants."
+
+Ewing also showed that among the living forms of Acarina we can trace
+out all the stages of advancing parasitism, semiparasitism, facultative
+parasitism, even to the fixed and permanent type, and finally to
+endoparasitism.
+
+Of the many parasitic forms, there are several species which are serious
+parasites of man and we shall consider the more important of these.
+Infestation by mites is technically known as _acariasis_.
+
+[Illustration: 43. Effect of the harvest mites on the skin of man.
+Photograph by J. C. Bradley.]
+
+
+The Trombidiidae, or Harvest Mites
+
+In many parts of this country it is impossible for a visitor to go into
+the fields and, particularly, into berry patches and among tall weeds
+and grass in the summer or early fall without being affected by an
+intolerable itching, which is followed, later, by a breaking out of
+wheals, or papules, surrounded by a bright red or violaceous aureola,
+(fig. 43). It is often regarded as a urticaria or eczema, produced by
+change of climate, an error in diet, or some condition of general
+health.
+
+Sooner or later, the victim finds that it is due to none of these, but
+to the attacks of an almost microscopic red mite, usually called
+"jigger" or "chigger" in this country. As the term "chigger" is applied
+to one of the true fleas, _Dermatophilus penetrans_, of the tropics,
+these forms are more correctly known as "harvest mites." Natives of an
+infested region may be so immune or accustomed to its attacks as to be
+unaware of its presence, though such immunity is by no means possessed
+by all who have been long exposed to the annoyance.
+
+[Illustration: 44. Harvest mites. (Larvae of Trombidium). After C. V.
+Riley.]
+
+The harvest mites, or chiggers, attacking man are larval forms,
+possessing three pairs of legs (fig. 44). Their systematic position was
+at first unknown and they were classed under a special genus _Leptus_, a
+name which is very commonly still retained in the medical literature. It
+is now known that they are the larval forms of various species of the
+genus _Trombidium_, a group of predaceous forms, the adults of which
+feed primarily on insects and their eggs. In this country the species
+best known are those to be found late in summer, as larvae at the base of
+the wings of houseflies or grasshoppers.
+
+There is much uncertainty as to the species of the larvae attacking man
+but it is clear that several are implicated. Bruyant has shown that in
+France the larvae _Trombidium inapinatum_ and _Trombidium holosericeum_
+are those most frequently found. The habit of attacking man is abnormal
+and the larvae die after entering the skin. Normally they are parasitic
+on various insects.
+
+Most recent writers agree that, on man, they do not bore into the skin,
+as is generally supposed, but enter a hair follicle or sebaceous gland
+and from the bottom of this, pierce the cutis with their elongate
+hypopharynx. According to Braun, there arises about the inserted
+hypopharynx a fibrous secretion--the so-called "beak" which is, in
+reality, a product of the host. Dr. J. C. Bradley, however, has made
+careful observations on their method of attack, and he assures us that
+the mite ordinarily remains for a long time feeding on the surface of
+the skin, where it produces the erythema above described. During this
+time it is not buried in the skin but is able to retreat rapidly into it
+through a hair follicle or sweat gland. The irritation from the mites
+ceases after a few days, but not infrequently the intolerable itching
+leads to so much scratching that secondary infection follows.
+
+Relief from the irritation may be afforded by taking a warm salt bath as
+soon as possible after exposure or by killing the mites by application
+of benzine, sulphur ointment or carbolized vaseline. When they are few
+in number, they can be picked out with a sterile needle.
+
+Much may be done in the way of warding off their attacks by wearing
+gaiters or close-woven stockings extending from ankle to the knee. Still
+more efficacious is the sprinkling of flowers of sulphur in the
+stockings and the underclothes from a little above the knee, down. The
+writers have known this to make it possible for persons who were
+especially susceptible to work with perfect comfort in badly infested
+regions. Powdered naphthalene is successfully used in the same way and
+as Chittenden (1906) points out, is a safeguard against various forms of
+man-infesting tropical insect pests.
+
+The question of the destruction of the mites in the field is sometimes
+an important one, and under some conditions, is feasible. Chittenden
+states that much can be accomplished by keeping the grass, weeds, and
+useless herbage mowed closely, so as to expose the mites to the sun. He
+believes that in some cases good may be done by dusting the grass and
+other plants, after cutting, with flowers of sulphur or by spraying with
+dilute kerosene emulsion in which sulphur has been mixed. More recently
+(1914) he calls attention to the value of cattle, and more especially
+sheep, in destroying the pests by tramping on them and by keeping the
+grass and herbage closely cropped.
+
+
+IXODOIDEA OR TICKS
+
+Until recently, the ticks attracted comparatively little attention from
+entomologists. Since their importance as carriers of disease has been
+established, interest in the group has been enormously stimulated and
+now they rank second only to the mosquitoes in the amount of detailed
+study that has been devoted to them.
+
+[Illustration: 45_a_. Argus persicus. Capitulum of male. After Nuttall
+and Warburton.]
+
+The ticks are the largest of the Acarina. They are characterized by the
+fact that the hypostome, or "tongue" (fig. 45) is large and file-like,
+roughened by sharp teeth. They possess a breathing pore on each side of
+the body, above the third or fourth coxae (fig. 45_b_).
+
+[Illustration: 45_b_. Left spiracle of nymph of _Argas persicus_. After
+Nuttall and Warburton.]
+
+There are two distinct families of the IXODOIDEA, differing greatly in
+structure, life-history and habits. These are the ARGASIDAE and the
+IXODIDAE. We shall follow Nuttall (1908) in characterizing these two
+families and in pointing out their biological differences, and shall
+discuss briefly the more important species which attack man. The
+consideration of the ticks as carriers of disease will be reserved for a
+later chapter.
+
+
+Argasidae
+
+In the ticks belonging to the family ARGASIDAE, there is comparatively
+little sexual dimorphism, while this is very marked in the Ixodidae. The
+capitulum, or so-called "head" is ventral, instead of terminal; the
+palpi are leg-like, with the segments subequal; the scutum, or dorsal
+shield, is absent; eyes, when present, are lateral, on supracoxal folds.
+The spiracles are very small; coxae unarmed; tarsi without ventral
+spurs, and the pulvilli are absent or rudimentary.
+
+In habits and life history the Argasidae present striking
+characteristics. In the first place, they are long-lived, a factor which
+counts for much in the maintenance of the species. They are intermittent
+feeders, being comparable with the bed-bug in this respect. There are
+two or more nymphal stages, and they may molt after attaining maturity.
+The female lays comparatively few eggs in several small batches.
+
+Nuttall (1911) concludes that "The Argasidae represent the relatively
+primitive type of ticks because they are less constantly parasitic than
+are the Ixodidae. Their nymphs and adults are rapid feeders and chiefly
+infest the habitat of their hosts. * * * Owing to the Argasidae infesting
+the habitats of their hosts, their resistance to prolonged starvation
+and their rapid feeding habits, they do not need to bring forth a large
+progeny, because there is less loss of life in the various stages, as
+compared with the Ixodidae, prior to their attaining maturity."
+
+[Illustration: 46. Argus persicus. Dorsal and ventral aspects. (x4).
+After Hassell.]
+
+Of the Argasidae, we have in the United States, several species which
+have been reported as attacking man.
+
+_Argas persicus_, the famous "Miana bug" (fig. 46), is a very widely
+distributed species, being reported from Europe, Asia, Africa, and
+Australia. It is everywhere preeminently a parasite of fowls. According
+to Nuttall it is specifically identical with _Argas americanus_ Packard
+or _Argas miniatus_ Koch, which is commonly found on fowls in the United
+States, in the South and Southwest. Its habits are comparable to those
+of the bed-bug. It feeds intermittently, primarily at night, and instead
+of remaining on its host, it then retreats to cracks and crevices.
+Hunter and Hooker (1908) record that they have found the larva to remain
+attached for five or eight days before dropping. Unlike the Ixodidae, the
+adults oviposit frequently.
+
+[Illustration: 47. Otiobius (Ornithodoros) megnini, head of nymph. After
+Stiles.]
+
+[Illustration: 48. Otiobius (Ornithodoros) megnini, male. (_a_) dorsal,
+(_b_) ventral aspect. After Nuttall and Warburton.]
+
+The most remarkable feature of the biology of this species is the great
+longevity, especially of the adult. Hunter and Hooker report keeping
+larvae confined in summer in pill boxes immediately after hatching for
+about two months while under similar conditions those of the Ixodid,
+_Boophilus annulatus_ lived for but two or three days. Many writers have
+recorded keeping adults for long periods without food. We have kept
+specimens in a tin box for over a year and a half and at the end of that
+time a number were still alive. Laboulliene kept unfed adults for over
+three years. In view of the effectiveness of sulphur in warding off the
+attacks of Trombidiidae, it is astonishing to find that Lounsbury has
+kept adults of _Argas persicus_ for three months in a box nearly filled
+with flowers of sulphur, with no apparent effect on them.
+
+We have already called attention to the occasional serious effects of
+the bites of this species. While such reports have been frequently
+discredited there can be no doubt that they have foundation in fact. The
+readiness with which this tick attacks man, and the extent to which old
+huts may be infested makes it especially troublesome.
+
+_Otiobius (Ornithodoros) megnini_, the "spinose ear-tick" (figs. 47,
+48), first described from Mexico, as occurring in the ears of horses, is
+a common species in our Southwestern States and is recorded by Banks as
+occurring as far north as Iowa.
+
+The species is remarkable for the great difference between the spiny
+nymph stage and the adult. The life history has been worked out by
+Hooker (1908). Seed ticks, having gained entrance to the ear, attach
+deeply down in the folds, engorge, and in about five days, molt; as
+nymphs with their spinose body they appear entirely unlike the larvae. As
+nymphs they continue feeding sometimes for months. Finally the nymph
+leaves the host, molts to form the unspined adult, and without further
+feeding is fertilized and commences oviposition.
+
+The common name is due to the fact that in the young stage the ticks
+occur in the ear of their hosts, usually horses or cattle. Not
+uncommonly it has been reported as occurring in the ear of man and
+causing very severe pain. Stiles recommends that it be removed by
+pouring some bland oil into the ear.
+
+Banks (1908) reports three species of _Ornithodoros_--_O. turicata_,
+_coriaceus_ and _talaje_--as occurring in the United States. All of these
+attack man and are capable of inflicting very painful bites.
+
+
+Ixodidae
+
+The ticks belonging to the family IXODIDAE (figs. 49 and 50) exhibit a
+marked sexual dimorphism. The capitulum is anterior, terminal, instead
+of ventral as in the Argasidae; the palpi are relatively rigid (except in
+the subfamily Ixodinae), with rudimentary fourth segment; scutum present;
+eyes, when present, dorsal, on side of scutum. The spiracles are
+generally large, situated well behind the fourth coxae; coxae generally
+with spurs; pulvilli always present.
+
+In habits and life history the typical Ixodidae differ greatly from
+the Argasidae. They are relatively short-lived, though some recent
+work indicates that their longevity has been considerably
+under-estimated. Typically, they are permanent feeders, remaining on the
+host, or hosts, during the greater part of their life. They molt twice
+only, on leaving the larval and the nymphal stages. The adult female
+deposits a single, large batch of eggs. Contrasting the habits of the
+Ixodidae to those of the Argasidae, Nuttall (1911) emphasizes that
+the Ixodidae are more highly specialized parasites. "The majority are
+parasitic on hosts having no fixed habitat and consequently all stages,
+as a rule, occur upon the host."
+
+[Illustration: 49. Ixodes ricinus; male, ventral aspect. After Braun and
+Luehe.]
+
+As mere parasites of man, apart from their power to transmit disease,
+the Ixodidae are much less important than the Argasidae. Many are
+reported as occasionally attacking man and of these the following native
+species may be mentioned.
+
+[Illustration: 50. Ixodes ricinus, var. scapularis, female. Capitulum
+and scutum; ventral aspect of capitulum; coxae; tarsus 4; spiracle;
+genital and anal grooves. After Nuttall and Warburton.]
+
+_Ixodes ricinus_, the European castor bean tick (figs. 49, 50), is a
+species which has been often reported from this country but Banks (1908)
+has shown that, though it does occur, practically all of the records
+apply to _Ixodes scapularis_ or _Ixodes cookei_. In Europe, _Ixodes
+ricinus_ is very abundant and very commonly attacks man. At the point
+of penetration of the hypostome there is more or less inflammation but
+serious injury does not occur unless there have been introduced
+pathogenic bacteria or, unless the tick has been abruptly removed,
+leaving the capitulum in the wound. Under the latter circumstances,
+there may be an abscess formed about the foreign body and occasionally,
+serious results have followed. Under certain conditions the tick, in
+various stages, may penetrate under the skin and produce a tumor, within
+which it may survive for a considerable period of time.
+
+_Ixodes cookei_ is given by Banks as "common on mammals in the Eastern
+States as far west as the Rockies." It is said to affect man severely.
+
+_Amblyomma americanum_, (fig. 158c), the "lone star tick," is widely
+distributed in the United States. Its common name is derived from the
+single silvery spot on the scutum of the female. Hunter and Hooker
+regard this species as, next to _Boophilus annulatus_, the most
+important tick in the United States. Though more common on cattle, it
+appears to attack mammals generally, and "in portions of Louisiana and
+Texas it becomes a pest of considerable importance to moss gatherers and
+other persons who spend much time in the forests."
+
+_Amblyomma cajennense_, noted as a pest of man in central and tropical
+America, is reported from various places in the south and southwestern
+United States.
+
+_Dermacentor variabilis_ is a common dog tick of the eastern United
+States. It frequently attacks man, but the direct effects of its bite
+are negligible.
+
+The "Rocky Mountain spotted fever tick" (_Dermacentor andersoni_
+according to Stiles, _D. venustus_ according to Banks) is, from the
+viewpoint of its effects on man, the most important of the ticks of the
+United States. This is because, as has been clearly established, it
+transmits the so-called "spotted fever" of man in our northwestern
+states. This phase of the subject will be discussed later and it need
+merely be mentioned here, that this species has been reported as causing
+painful injuries by its bites. Dr. Stiles states that he has seen cases
+of rather severe lymphangitis and various sores and swellings developing
+from this cause. In one case, of an individual bitten near the elbow,
+the arm became very much swollen and the patient was confined in bed for
+several days. The so-called tick paralysis produced by this species is
+discussed in a preceding chapter.
+
+There are many other records of various species of ticks attacking man,
+but the above-mentioned will serve as typical and it is not necessary to
+enter into greater detail.
+
+
+TREATMENT OF TICK BITES--When a tick attaches to man the first thing to
+be done is to remove it without leaving the hypostome in the wound to
+fester and bring about secondary effects. This is best accomplished by
+applying to the tick's body some substance which will cause it to more
+readily loosen its hold. Gasoline or petroleum, oil or vaseline will
+serve. For removing the spinose ear-tick, Stiles recommends pouring some
+bland oil into the ear. Others have used effectively a pledget of cotton
+soaked in chloroform.
+
+In general, the treatment recommended by Wellman for the bites of
+_Ornithodoros moubata_ will prove helpful. It consists of prolonged
+bathing in very hot water, followed by the application of a strong
+solution of bicarbonate of soda, which is allowed to dry upon the skin.
+He states that this treatment is comforting. For severe itching he
+advises smearing the bites with vaseline, which is slightly impregnated
+with camphor or menthol. Medical aid should be sought when complications
+arise.
+
+The DERMANYSSIDAE are Gamasid mites which differ from others of the group
+in that they are parasitic on vertebrates. None of the species normally
+attack man, but certain of them, especially the poultry mite, may be
+accidental annoyances.
+
+[Illustration: 51. Dermanyssus gallinae, female. After Delafond.]
+
+_Dermanyssus gallinae_ (fig. 51), the red mite of poultry, is an
+exceedingly common and widespread parasite of fowls. During the day it
+lives in cracks and crevices of poultry houses, under supports of
+roosts, and in litter of the food and nests, coming out at night to
+feed. They often attack people working in poultry houses or handling
+and plucking infested fowls. They may cause an intense pruritis, but
+they do not produce a true dermatosis, for they do not find conditions
+favorable for multiplication on the skin of man.
+
+
+Tarsonemidae
+
+The representatives of the family TARSONEMIDAE are minute mites, with the
+body divided into cephalothorax and abdomen. There is marked sexual
+dimorphism. The females possess stigmata at the anterior part of the
+body, at the base of the rostrum, and differ from all other mites in
+having on each side, a prominent clavate organ between the first and
+second legs. The larva, when it exists, is hexapodous and resembles the
+adult. A number of the species are true parasites on insects, while
+others attack plants. Several of them may be accidental parasites of
+man.
+
+[Illustration: 52. Pediculoides ventricosus, female. After Webster.]
+
+[Illustration: 53. Pediculoides ventricosus, gravid female. (x80).
+After Webster.]
+
+_Pediculoides ventricosus_ (fig. 52 and 53) is, of all the
+Tarsonemidae reported, the one which has proved most troublesome to
+man. It is a predaceous species which attacks a large number of insects
+but which has most commonly been met with by man through its fondness
+for certain grain-infesting insects, notably the Angoumois grain moth,
+_Sitotroga cerealella_, and the wheat straw-worm, _Isosoma grande_. In
+recent years it has attracted much attention in the United States and
+its distribution and habits have been the object of detailed study by
+Webster (1901).
+
+[Illustration: 54. Pediculoides ventricosus, male. After Braun.]
+
+There is a very striking sexual dimorphism in this species. The
+non-gravid female is elongate, about 200u by 70u (fig. 52), with the
+abdomen slightly striated longitudinally. The gravid female (fig. 53)
+has the abdomen enormously swollen, so that it is from twenty to a
+hundred times greater than the rest of the body. The species is
+viviparous and the larvae undergo their entire growth in the body of the
+mother. They emerge as sexually mature males and females which soon
+pair. The male (fig. 54) is much smaller, reaching a length of only 320u
+but is relatively broad, 80u, and angular. Its abdomen is very greatly
+reduced.
+
+As far back as 1850 it was noted as causing serious outbreaks of
+peculiar dermatitis among men handling infested grain. For some time the
+true source of the difficulty was unknown and it was even believed that
+the grain had been poisoned. Webster has shown that in this country (and
+probably in Europe as well) its attacks have been mistaken for those of
+the red bugs or "chiggers" (larval Trombiidae). More recently a number of
+outbreaks of a mysterious "skin disease" were traced to the use of straw
+mattresses, which were found to be swarming with these almost
+microscopic forms which had turned their attentions to the occupants of
+the beds. Other cases cited were those of farmers running wheat through
+a fanning mill, and of thrashers engaged in feeding unthrashed grain
+into the cylinder of the machine.
+
+[Illustration: 55. Lesions produced by the attacks of Pediculoides
+ventricosus. After Webster.]
+
+The medical aspects of the question have been studied especially by
+Schamberg and Goldberger and from the latter's summary (1910) we derive
+the following data. Within twelve to sixteen hours after exposure,
+itching appears and in severe cases, especially where exposure is
+continued night after night by sleeping on an infested bed, the itching
+may become almost intolerable. Simultaneously, there appears an eruption
+which characteristically consists of wheals surrounded by a vesicle
+(fig. 55). The vesicle as a rule does not exceed a pin head in size but
+may become as large as a pea. Its contents rapidly become turbid and in
+a few hours it is converted into a pustule. The eruption is most
+abundant on the trunk, slight on the face and extremities and almost
+absent on the feet and hands. In severe cases there may be
+constitutional disturbances marked, at the outset, by chilliness,
+nausea, and vomiting, followed for a few days by a slight elevation of
+temperature, with the appearance of albumin in the urine. In some cases
+the eruption may simulate that of chicken-pox or small-pox.
+
+Treatment for the purpose of killing the mites is hardly necessary as
+they attach feebly to the surface and are readily brushed off by
+friction of the clothes. "Antipruritic treatment is always called for;
+warm, mildly alkaline baths or some soothing ointment, such as zinc
+oxide will be found to fulfil this indication." Of course, reinfestation
+must be guarded against, by discarding, or thoroughly fumigating
+infested mattresses, or by avoiding other sources. Goldberger suggests
+that farm laborers who must work with infested wheat or straw might
+protect themselves by anointing the body freely with some bland oil or
+grease, followed by a change of clothes and bath as soon as their work
+is done. We are not aware of any experiments to determine the effect of
+flowers of sulphur, but their efficiency in the case of "red bugs"
+suggests that they are worth a trial against _Pediculoides_.
+
+Various species of TYROGLYPHIDAE (fig. 150_f_) may abound on dried fruits
+and other products and attacking persons handling them, may cause a
+severe dermatitis, comparable to that described above for _Pediculoides
+ventricosus_. Many instances of their occurrence as such temporary
+ectoparasites are on record. Thus, workers who handle vanilla pods are
+subject to a severe dermatitis, known as vanillism, which is due to the
+attacks of _Tyroglyphus siro_, or a closely related species. The
+so-called "grocer's itch" is similarly caused by mites infesting various
+products. Castellani has shown that in Ceylon, workers employed in the
+copra mills, where dried cocoanut is ground up for export, are much
+annoyed by mites, which produce the so-called "copra itch." The skin of
+the hands, arms and legs, and sometimes of the whole body, except the
+face, is covered by fairly numerous, very pruriginous papules, often
+covered by small, bloody crusts due to scratching. The condition is
+readily mistaken for scabies. It is due to the attacks of _Tyroglyphus
+longior castellanii_ which occur in enormous numbers in some samples of
+the copra.
+
+
+Sarcoptidae
+
+The SARCOPTIDAE are minute whitish mites, semi-globular in shape, with a
+delicate transversely striated cuticula. They lack eyes and tracheae. The
+mouth-parts are fused at the base to form a cone which is usually
+designated as the head. The legs are short and stout, and composed of
+five segments. The tarsi may or may not possess a claw and may terminate
+in a pedunculated sucker, or simple long bristle, or both. The presence
+or absence of these structures and their distribution are much used in
+classification. The mites live on or under the skin of mammals and
+birds, where they produce the disease known as scabies, mange, or itch.
+Several species of the Sarcoptidae attack man but the most important of
+these, and the one pre-eminent as the "itch mite" is _Sarcoptes
+scabiei_.
+
+The female of _Sarcoptes scabiei_, of man, is oval and yellowish white;
+the male more rounded and of a somewhat reddish tinge, and much smaller.
+The body is marked by transverse striae which are partly interrupted on
+the back. There are transverse rows of scales, or pointed spines, and
+scattered bristles on the dorsum.
+
+[Illustration: 56_a_. Sarcoptes scabiei, male. (x100). After
+Furstenberg.]
+
+The male (fig. 56) which is from 200-240u in length, and 150-200u in
+breadth, possesses pedunculated suckers on each pair of legs except the
+third, which bears, instead, a long bristle. The female (fig. 56)
+300-450u in length and 250-350u in breadth, has the pedunculated suckers
+on the first and second pairs of legs, only, the third and fourth
+terminating in bristles.
+
+[Illustration: 56_b_. Sarcoptes scabiei, female. (x100.) After
+Furstenberg.]
+
+The mite lives in irregular galleries from a few millimeters to several
+centimeters in length, which it excavates in the epidermis (fig. 57). It
+works especially where the skin is thin, such as between the fingers, in
+the bend of the elbows and knees, and in the groin, but it is by no
+means restricted to these localities. The female, alone, tunnels into
+the skin; the males remain under the superficial epidermal scales, and
+seldom are found, as they die soon after mating.
+
+As she burrows into the skin the female deposits her eggs, which measure
+about 150 x 100u. Furstenberg says that each deposits an average of
+twenty-two to twenty-four eggs, though Gudden reports a single burrow as
+containing fifty-one. From these there develop after about seven days,
+the hexapod larvae. These molt on the sixteenth day to form an octopod
+nymph, which molts again the twenty-first day. At the end of the fourth
+week the nymphs molt to form the sexually mature males and the so-called
+pubescent females. These pair, the males die, and the females again cast
+their skin, and become the oviparous females. Thus the life cycle is
+completed in about twenty-eight days.
+
+The external temperature exercises a great influence on the development
+of the mites and thus, during the winter, the areas of infestation not
+only do not spread, but they become restricted. As soon as the
+temperature rises, the mites increase and the infestation becomes much
+more extensive.
+
+[Illustration: 57. Sarcoptes scabiei. Diagrammatic representation of the
+course in the skin of man.]
+
+In considering the possible sources of infestation, and the chances of
+reinfestation after treatment, the question of the ability of the mite
+to live apart from its host is a very important one. Unfortunately there
+are few reliable data on this subject. Gerlach found that, exposed in
+the dry, warm air of a room they became very inactive within twenty-four
+hours, that after two days they showed only slight movement, and that
+after three or four days they could not be revived by moisture and
+warming. The important fact was brought out that in moist air, in folded
+soiled underwear, they survived as long as ten days. Bourguignon found
+that under the most favorable conditions the mites of _Sarcoptes scabiei
+equi_ would live for sixteen days.
+
+The disease designated the "itch" or "scabies," in man has been known
+from time immemorial, but until within less than a hundred years it was
+almost universally attributed to malnutrition, errors of diet, or "bad
+blood." This was in spite of the fact that the mite was known to Mouffet
+and that Bonomo had figured both the adult and the egg and had declared
+the mite the sole cause of the disease. In 1834 the Corsican medical
+student, Francis Renucci, demonstrated the mite before a clinic in Saint
+Louis Hospital in Paris and soon thereafter there followed detailed
+studies of the life history of the various itch mites of man and
+animals.
+
+[Illustration: 58. Scabies on the hand. From portfolio of Dermochromes
+by permission of Rebman & Co., of New York. Publishers.]
+
+The disease is a cosmopolitan one, being exceedingly abundant in some
+localities. Its spread is much favored where large numbers of people are
+crowded together under insanitary conditions and hence it increases
+greatly during wars and is widely disseminated and abundant immediately
+afterwards. Though more commonly to be met with among the lower classes,
+it not infrequently appears among those of the most cleanly, careful
+habits, and it is such cases that are most liable to wrong diagnosis by
+the physician.
+
+Infection occurs solely through the passage, direct or indirect, of the
+young fertilized females to the skin of a healthy individual. The adult,
+oviparous females do not quit their galleries and hence do not serve to
+spread the disease. The young females move about more or less at night
+and thus the principal source of infestation is through sleeping in the
+same bed with an infested person, or indirectly through bedclothes, or
+even towels or clothing. Diurnal infestation through contact or clothing
+is exceptional. Many cases are known of the disease being contracted
+from animals suffering from scabies, or mange.
+
+When a person is exposed to infestation, the trouble manifests itself
+after eight or ten days, though there usually elapses a period of twenty
+to thirty days before there is a suspicion of anything serious. The
+first symptom is an intense itching which increases when the patient is
+in bed. When the point of irritation is examined the galleries may
+usually be seen as characteristic sinuous lines, at first whitish in
+color but soon becoming blackish because of the contained eggs and
+excrement. The galleries, which may not be very distinct in some cases,
+may measure as much as four centimeters in length. Little vesicles, of
+the size of a pin head are produced by the secretions of the feeding
+mite; they are firm, and projecting, and contain a limpid fluid. Figures
+58 and 59 show the typical appearance of scabies on the hands, while
+figure 60 shows a severe general infestation. The intolerable itching
+induces scratching and through this various complications may arise. The
+lesions are not normally found on the face and scalp, and are rare on
+the back.
+
+[Illustration: 59. Scabies on the hand. After Duhring.]
+
+[Illustration: 60. Generalized infection of Scabies. After Morrow.]
+
+Formerly, scabies was considered a very serious disease, for its cause
+and method of treatment were unknown, and potentially it may continue
+indefinitely. Generation after generation of the mites may develop and
+finally their number become so great that the general health of the
+individual is seriously affected. Now that the true cause of the disease
+is known, it is easily controlled.
+
+Treatment usually consists in softening the skin by friction with soap
+and warm water, followed by a warm bath, and then applying some
+substance to kill the mites. Stiles gives the following directions,
+modified from Bourguignon's, as "a rather radical guide, to be modified
+according to facilities and according to the delicacy of the skin or
+condition of the patient":
+
+1. The patient, stripped naked, is energetically rubbed all over (except
+the head) for twenty minutes, with green soap and warm water. 2. He is
+then placed in a warm bath for thirty minutes, during which time the
+rubbing is continued. 3. The parasiticide is next rubbed in for twenty
+minutes and is allowed to remain on the body for four or five hours; in
+the meantime the patient's clothes are sterilized, to kill the eggs or
+mites attached to them. 4. A final bath is taken to remove the
+parasiticide.
+
+The parasiticide usually relied on is the officinal sulphur ointment of
+the United States pharmacopoeia. When infestation is severe it is
+necessary to repeat treatment after three or four days in order to kill
+mites which have hatched from the eggs.
+
+The above treatment is too severe for some individuals and may, of
+itself, produce a troublesome dermatitis. We have seen cases where the
+treatment was persisted in and aggravated the condition because it was
+supposed to be due to the parasite. For delicate-skinned patients the
+use of balsam of Peru is very satisfactory, and usually causes no
+irritation whatever. Of course, sources of reinfection should be
+carefully guarded against.
+
+_Sarcoptes scabiei crustosae_, which is a distinct variety, if not
+species, of the human itch mite, is the cause of so-called Norwegian
+itch. This disease is very contagious, and is much more resistant than
+the ordinary scabies. Unlike the latter, it may occur on the face and
+scalp.
+
+_Sarcoptes scabiei_ not only attacks man but also occurs on a large
+number of mammals. Many species, based on choice of host, and minute
+differences in size and secondary characters, have been established, but
+most students of the subject relegate these to varietal rank. Many of
+them readily attack man, but they have become sufficiently adapted to
+their normal host so that they are usually less persistent on man.
+
+_Notoedres cati_ (usually known as _Sarcoptes minor_) is a species of
+itch mites which produce an often fatal disease of cats. The body is
+rounded and it is considerably smaller than _Sarcoptes scabiei_, the
+female (fig. 61) measuring 215-230u long and 165-175u wide; the males
+145-150u by 120-125u. The most important character separating
+_Notoedres_ from _Sarcoptes_ is the position of the anus, which is
+dorsal instead of terminal. The mite readily transfers to man but does
+not persist, the infestation usually disappearing spontaneously in about
+two weeks. Infested cats are very difficult to cure, unless treatment is
+begun at the very inception of the outbreak, and under ordinary
+circumstances it is better to kill them promptly, to avoid spread of the
+disease to children and others who may be exposed.
+
+[Illustration: 61. Notoedres cati, male and female. After Railliet.]
+
+
+Demodecidae
+
+The DEMODECIDAE are small, elongate, vermiform mites which live in the
+hair follicles of mammals. The family characteristics will be brought
+out in the discussion of the species infesting man, _Demodex
+folliculorum_.
+
+[Illustration: 62. Demodex folliculorum. (x200) After Blanchard.]
+
+_Demodex folliculorum_ (fig. 62) is to be found very commonly in the
+hair follicles and sebaceous glands of man. It is vermiform in
+appearance, and with the elongate abdomen transversely striated so as to
+give it the appearance of segmentation. The female is 380-400u long by
+45u; the male 300u by 40u. The three-jointed legs, eight in number, are
+reduced to mere stubs in the adult. The larval form is hexopod. These
+mites thus show in their form a striking adaptation to their
+environment. In the sebaceous glands and hair follicles they lie with
+their heads down (fig. 63). Usually there are only a few in a gland, but
+Gruby has counted as many as two hundred.
+
+[Illustration: 63. Demodex folliculorum. Section through skin showing
+the mites in situ. Magnification of Nos. 1, 2, 6 and 7, x150; Nos, 3,
+4, 5, x450. After Megnin.]
+
+The frequency with which they occur in man is surprising. According to
+European statistics they are found in 50 per cent to 60 per cent or even
+more. Gruby found them in forty out of sixty persons examined. These
+figures are very commonly quoted, but reliable data for the United
+States seem to be lacking. Our studies indicate that it is very much
+less common in this country than is generally assumed.
+
+The Demodex in man does not, as a rule, cause the slightest
+inconvenience to its host. It is often stated that they give rise to
+comedons or "black-heads" but there is no clear evidence that they are
+ever implicated. Certain it is that they are not the usual cause. A
+variety of the same, or a very closely related species of _Demodex_, on
+the dog gives rise to the very resistant and often fatal follicular
+mange.
+
+
+HEXAPODA OR TRUE INSECTS
+
+The HEXAPODA, or true insects, are characterized by the fact that the
+adult possesses three pairs of legs. The body is distinctly segmented
+and is divided into head, thorax, and abdomen.
+
+The mouth-parts in a generalized form, consist of an upper lip, or
+_labrum_, which is a part of the head capsule, and a central unpaired
+_hypopharynx_, two _mandibles_, two _maxillae_ and a lower lip, or
+_labium_, made up of the fused pair of second maxillae. These parts may
+be greatly modified, dependent upon whether they are used for biting,
+sucking, piercing and sucking, or a combination of biting and sucking.
+
+Roughly speaking, insects may be grouped into those which undergo
+_complete metamorphosis_ and those which have _incomplete
+metamorphosis_. They are said to undergo complete metamorphosis when the
+young form, as it leaves the egg, bears no resemblance to the adult. For
+example, the maggot changes to a quiescent pupa and from this emerges
+the winged active fly. They undergo incomplete metamorphosis, when the
+young insect, as it leaves the egg, resembles the adult to a greater or
+less extent, and after undergoing a certain number of molts becomes
+sexually mature.
+
+Representatives of several orders have been reported as accidental or
+faculative parasites of man, but the true parasites are restricted to
+four orders. These are the Siphunculata; the Hemiptera, the Diptera and
+the Siphonaptera.
+
+
+SIPHUNCULATA
+
+The order SIPHUNCULATA was established by Meinert to include the true
+sucking lice. These are small wingless insects, with reduced
+mouth-parts, adapted for sucking; thorax apparently a single piece due
+to indistinct separation of its three segments: the compound eyes
+reduced to a single ommatidium on each side. The short, powerful legs
+are terminated by a single long claw. Metamorphosis incomplete.
+
+There has been a great deal of discussion regarding the structure of the
+mouth-parts, and the relationships of the sucking lice, and the
+questions cannot yet be regarded as settled. The conflicting views are
+well represented by Cholodkovsky (1904 and 1905) and by Enderlein
+(1904).
+
+[Illustration: 64. Pediculus showing the blind sac (_b_) containing the
+mouth parts (_a_) beneath the alimentary canal (_p_). After Pawlowsky.]
+
+Following Graber, it is generally stated that the mouth-parts consist of
+a short tube furnished with hooks in front, which constitutes the lower
+lip, and that within this is a delicate sucking tube derived from the
+fusion of the labrum and the mandibles. Opposed to this, Cholodkovsky
+and, more recently, Pawlowsky, (1906), have shown that the piercing
+apparatus lies in a blind sac under the pharynx and opening into the
+mouth cavity (fig. 64). It does not form a true tube but a furrow with
+its open surface uppermost. Eysell has shown that, in addition, there is
+a pair of chitinous rods which he regards as the homologues of the
+maxillae.
+
+When the louse feeds, it everts the anterior part of the mouth cavity,
+with its circle of hooks. The latter serve for anchoring the bug, and
+the piercing apparatus is then pushed out.
+
+[Illustration: 65. Pediculus humanus, ventral aspect of male. (x10)]
+
+Most writers have classed the sucking lice as a sub-order of the
+Hemiptera, but the more recent anatomical and developmental studies
+render this grouping untenable. An important fact, bearing on the
+question, is that, as shown by Gross, (1905), the structure of the
+ovaries is radically different from that of the Hemiptera.
+
+Lice infestation and its effects are known medically as _pediculosis_.
+Though their continued presence is the result of the grossest neglect
+and filthiness, the original infestation may be innocently obtained and
+by people of the most careful habits.
+
+Three species commonly attack man. Strangely enough, there are very few
+accurate data regarding their life history.
+
+_Pediculus humanus_ (fig. 65), the head louse, is the most widely
+distributed. It is usually referred to in medical literature as
+_Pediculus capitis_, but the Linnean specific name has priority. In
+color it is of a pale gray, blackish on the margins. It is claimed by
+some authors that the color varies according to the color of the skin of
+the host. The abdomen is composed of seven distinct segments, bearing
+spiracles laterally. There is considerable variation in size. The males
+average 1.8 mm. and the females 2.7 mm. in length.
+
+The eggs, fifty to sixty in number, stick firmly to the hairs of the
+host and are known as nits. They are large and conspicuous, especially
+on dark hair and are provided with an operculum, or cap, at the free
+end, where the nymphs emerge. They hatch in about six days and about the
+eighteenth day the young lice are sexually mature.
+
+[Illustration: 66. Pediculosis of the head. The illustration shows the
+characteristic indications of the presence of lice, viz: the occipital
+eczema gluing the hairs together, the swollen cervical glands, and the
+porrigo, or eruption of contagious pustules upon the neck. After Fox.]
+
+The head lice live by preference on the scalp of their host but
+occasionally they are found on the eyelashes and beard, or in the pubic
+region. They may also occur elsewhere on the body. The penetration of
+the rostrum into the skin and the discharge of an irritating saliva
+produce a severe itching, accompanied by the formation of an eczema-like
+eruption (fig. 66). When the infestation is severe, the discharge from
+the pustules mats down the hair, and scabs are formed, under which the
+insects swarm. "If allowed to run, a regular carapace may form, called
+_trichoma_, and the head exudes a foetid odor. Various low plants may
+grow in the trichoma, the whole being known as _plica
+palonica_."--Stiles.
+
+Sources of infestation are various. School children may obtain the lice
+from seatmates, by wearing the hats or caps of infested mates, or by the
+use, in common, of brushes and combs. They may be obtained from infested
+beds or sleeper berths. Stiles reports an instance in which a large
+number of girls in a fashionable boarding school developed lousiness a
+short time after traveling in a sleeping car.
+
+Treatment is simple, for the parasites may readily be controlled by
+cleanliness and washing the head with a two per cent solution of
+carbolic acid or even kerosene. The latter is better used mixed with
+equal parts of olive oil, to avoid irritation. The treatment should be
+applied at night and followed the next morning by a shampoo with soap
+and warm water. It is necessary to repeat the operation in a few days.
+Xylol, used pure, or with the addition of five per cent of vaseline, is
+also very efficacious. Of course, the patient must be cautioned to stay
+away from a lighted lamp or fire while using either the kerosene or
+xylol. While these treatments will kill the eggs or nits, they will not
+remove them from the hairs. Pusey recommends repeated washings with
+vinegar or 25 per cent of acetic acid in water, for the purpose of
+loosening and removing the nits.
+
+Treatment of severe infestations in females is often troublesome on
+account of long hair. For such cases the following method recommended by
+Whitfield (1912) is especially applicable:
+
+The patient is laid on her back on the bed with her head over the edge,
+and beneath the head is placed a basin on a chair so that the hair lies
+in the basin. A solution of 1 in 40 carbolic acid is then poured over
+the hair into the basin and sluiced backwards and forwards until the
+whole of the hair is thoroughly soaked with it. It is especially
+necessary that care should be taken to secure thorough saturation of the
+hair over the ears and at the nape of the neck, since these parts are
+not only the sites of predilection of the parasites but they are apt to
+escape the solution. This sluicing is carried out for ten minutes by the
+clock. At the end of ten minutes the hair is lifted from the basin and
+allowed to drain, but is not dried or even thoroughly wrung out. The
+whole head is then swathed with a thick towel or better, a large piece
+of common house flannel, which is fastened up to form a sort of turban,
+and is allowed to remain thus for an hour. It can then be washed or
+simply allowed to dry, as the carbolic quickly disperses. At the end of
+this period every pediculus and what is better, every ovum is dead and
+no relapse will occur unless there is exposure to fresh contagion.
+Whitfield states that there seem to be no disadvantages in this method,
+which he has used for years. He has never seen carboluria result from
+it, but would advise first cutting the hair of children under five years
+of age.
+
+_Pediculus corporis_ (= _P. vestimenti_) the body louse, is larger than
+the preceding species, the female measuring 3.3 mm., and the male 3 mm.
+in length. The color is a dirty white, or grayish. _P. corporis_ has
+been regarded by some authorities as merely a variety of _P. humanus_
+but Piaget maintains there are good characters separating the two
+species.
+
+The body louse lives in the folds and seams of the clothing of its host,
+passing to the skin only when it wishes to feed. Brumpt states that he
+has found enormous numbers of them in the collars of glass-ware or
+grains worn by certain naked tribes in Africa.
+
+Exact data regarding the life-history of this species have been
+supplied, in part, by the work of Warburton (1910), cited by Nuttall. He
+found that _Pediculus corporis_ lives longer than _P. humanus_ under
+adverse conditions. This is doubtless due to its living habitually on
+the clothing, whereas _humanus_ lives upon the head, where it has more
+frequent opportunities of feeding. He reared a single female upon his
+own person, keeping the louse enclosed in a cotton-plugged tube with a
+particle of cloth to which it could cling. The tube was kept next to his
+body, thus simulating the natural conditions of warmth and moisture
+under which the lice thrive. The specimen was fed twice daily, while it
+clung to the cloth upon which it rested. Under these conditions she
+lived for one month. Copulation commenced five days after the female had
+hatched and was repeated a number of times, sexual union lasting for
+hours. The female laid one hundred and twenty-four eggs within
+twenty-five days.
+
+The eggs hatched after eight days, under favorable conditions, such as
+those under which the female was kept. They did not hatch in the cold.
+Eggs kept near the person during the day and hung in clothing by the
+bedside at night, during the winter, in a cold room, did not hatch until
+the thirty-fifth day. When the nymphs emerge from the eggs, they feed at
+once, if given a chance to do so. They are prone to scatter about the
+person and abandon the fragment of cloth to which the adult clings.
+
+The adult stage is reached on the eleventh day, after three molts, about
+four days apart. Adults enter into copulation about the fifth day and as
+the eggs require eight days for development, the total cycle, under
+favorable conditions, is about twenty-four days. Warburton's data differ
+considerably from those commonly quoted and serve to emphasize the
+necessity for detailed studies of some of the commonest of parasitic
+insects.
+
+Body lice are voracious feeders, producing by their bites and the
+irritating saliva which they inject, rosy elevations and papules which
+become covered with a brownish crust. The intense itching provokes
+scratching, and characteristic white scars (fig. 67) surrounded by
+brownish pigment (fig. 68) are formed. The skin may become thickened and
+take on a bronze tinge. This melanoderma is especially marked in the
+region between the shoulders but it may become generalized, a prominent
+characteristic of "vagabond's disease." According to Dubre and Beille,
+this melanoderma is due to a toxic substance secreted by the lice, which
+indirectly provokes the formation of pigment.
+
+[Illustration: 67. Pediculosis in man caused by the body louse. After
+Morrow.]
+
+Control measures, in the case of the body louse, consist in boiling or
+steaming the clothes or in some cases, sterilizing by dry heat. The
+dermatitis may be relieved by the use of zinc-oxide ointment, to which
+Pusey recommends that there be added, on account of their parasiticidal
+properties, sulphur and balsam of Peru, equal parts, 15 to 30 grains to
+the ounce.
+
+_Phthirius pubis_ (= _P. inguinalis_), the pubic louse, or so-called
+"crab louse," differs greatly from the preceding in appearance. It is
+characterized by its relatively short head which fits into a broad
+depression in the thorax. The latter is broad and flat and merges into
+the abdomen. The first pair of legs is slender and terminated by a
+straight claw. The second and third pairs of legs are thicker and are
+provided with powerful claws fitted for clinging to hairs. The females
+(fig. 69) measure 1.5 to 2 mm. in length by 1.5 mm. in breadth. The male
+averages a little over half as large. The eggs, or nits, are fixed at
+the base of the hairs. Only a few, ten to fifteen are deposited by a
+single female, and they hatch in about a week's time. The young lice
+mature in two weeks.
+
+The pubic louse usually infests the hairs of the pubis and the perineal
+region. It may pass to the arm pits or even to the beard or moustache.
+Rarely, it occurs on the eyelids, and it has even been found, in a very
+few instances, occurring in all stages, on the scalp. Infestation may be
+contracted from beds or even from badly infested persons in a crowd. We
+have seen several cases which undoubtedly were due to the use of public
+water closets. It produces papular eruption and an intense pruritis.
+When abundant, there occurs a grayish discoloration of the skin which
+Duguet has shown is due to a poisonous saliva injected by the louse, as
+is the melanoderma caused by the body louse.
+
+[Illustration: 68. Melanoderma caused by the body louse. From Portfolio
+of Dermochromes, by permission of Rebman & Co., New York, Publishers.]
+
+The pubic louse may be exterminated by the measures recommended for the
+head louse, or by the use of officinal mercurial ointment.
+
+[Illustration: 69. Phthirius pubis. Ventral aspect of female. (x12).]
+
+
+HEMIPTERA
+
+Several species of HEMIPTERA-HETEROPTERA are habitual parasites of man,
+and others occur as occasional or accidental parasites. Of all these,
+the most important and widespread are the bed-bugs, belonging to the
+genus _Cimex_ (= _Acanthia_).
+
+
+THE BED-BUGS--The bed-bugs are characterized by a much flattened oval
+body, with the short, broad head unconstricted behind, and fitting into
+the strongly excavated anterior margin of the thorax. The compound eyes
+are prominent, simple eyes lacking. Antennae four-jointed, the first
+segment short, the second long and thick, and the third and fourth
+slender. The tarsi are short and three segmented.
+
+It is often assumed in the literature of the subject that there is but a
+single species of _Cimex_ attacking man, but several such species are to
+be recognized. These are distinguishable by the characters given in
+Chapter XII. We shall consider especially _Cimex lectularius_, the most
+common and widespread species.
+
+_Cimex lectularius_ (= _Acanthia lectularia_, _Clinocoris
+lectularius_), is one of the most cosmopolitan of human parasites but,
+like the lice, it has been comparatively little studied until recent
+years, when the possibility that it may be concerned with the
+transmission of various diseases has awakened interest in the details of
+its life-history and habits.
+
+[Illustration: 70. Cimex lectularius adult and eggs. Photograph by M. V.
+S.]
+
+The adult insect (fig. 70) is 4-5 mm. long by 3 mm. broad, reddish brown
+in color, with the beak and body appendages lighter in color. The short,
+broad and somewhat rectangular head has no neck-like constriction but
+fits into the broadly semilunar prothorax. The four segmented labium or
+proboscis encloses the lancet-like maxillae and mandibles. The distal
+of the four antennal segments is slightly club-shaped. The prothorax is
+characteristic of the species, being deeply incised anteriorly and with
+its thin lateral margins somewhat turned up. The mesothorax is
+triangular, with the apex posteriorly, and bears the greatly atrophied
+first pair of wings. There is no trace of the metathoracic pair. The
+greatly flattened abdomen has eight visible segments, though in reality
+the first is greatly reduced and has been disregarded by most writers.
+The body is densely covered with short bristles and hairs, the former
+being peculiarly saber-shaped structures sharply toothed at the apex and
+along the convex side (fig. 159_b_).
+
+The peculiar disagreeable odor of the adult bed-bug is due to the
+secretion of the stink glands which lie on the inner surface of the
+mesosternum and open by a pair of orifices in front of the metacoxae,
+near the middle line. In the nymphs, the thoracic glands are not
+developed but in the abdomen there are to be found three unpaired dorsal
+stink glands, which persist until the fifth molt, when they become
+atrophied and replaced by the thoracic glands. The nymphal glands occupy
+the median dorsal portion of the abdomen, opening by paired pores at the
+anterior margin of the fourth, fifth and sixth segments. The secretion
+is a clear, oily, volatile fluid, strongly acid in reaction. Similar
+glands are to be found in most of the Hemiptera-Heteroptera and their
+secretion is doubtless protective, through being disagreeable to the
+birds. In the bed-bug, as Marlatt points out, "it is probably an
+illustration of a very common phenomenon among animals, i.e., the
+persistence of a characteristic which is no longer of any special value
+to the possessor." In fact, its possession is a distinct disadvantage to
+the bed-bug, as the odor frequently reveals the presence of the bugs,
+before they are seen.
+
+The eggs of the bed-bug (fig. 70) are pearly white, oval in outline,
+about a millimeter long, and possess a small operculum or cap at one
+end, which is pushed off when the young hatches. They are laid
+intermittently, for a long period, in cracks and crevices of beds and
+furniture, under seams of mattresses, under loose wall paper, and
+similar places of concealment of the adult bugs. Girault (1905) observed
+a well-fed female deposit one hundred and eleven eggs during the
+sixty-one days that she was kept in captivity. She had apparently
+deposited some of her eggs before being captured.
+
+The eggs hatch in six to ten days, the newly emerged nymphs being about
+1.5 mm. in length and of a pale yellowish white color. They grow slowly,
+molting five times. At the last molt the mesathoracic wing pads appear,
+characteristic of the adult. The total length of the nymphal stage
+varies greatly, depending upon conditions of food supply, temperature
+and possibly other factors. Marlatt (1907) found under most favorable
+conditions a period averaging eight days between molting which, added to
+an equal egg period, gave a total of about seven weeks from egg to adult
+insect. Girault (1912) found the postembryonic period as low as
+twenty-nine days and as high as seventy days under apparently similar
+and normal conditions of food supply. Under optimum and normal
+conditions of food supply, beginning August 27, the average nymphal life
+was 69.9 days; average number of meals 8.75 and the molts 5. Under
+conditions allowing about half the normal food supply the average
+nymphal life was from 116.9 to 139 days. Nymphs starved from birth lived
+up to 42 days. We have kept unfed nymphs, of the first stage, alive in a
+bottle for 75 days. The interesting fact was brought out that under
+these conditions of minimum food supply there were sometimes six molts
+instead of the normal number.
+
+The adults are remarkable for their longevity, a factor which is of
+importance in considering the spread of the insect and methods of
+control. Dufour (1833) (not De Geer, as often stated) kept specimens for
+a year, in a closed vial, without food. This ability, coupled with their
+willingness to feed upon mice, bats, and other small mammals, and even
+upon birds, accounts for the long periods that deserted houses and camps
+may remain infested. There is no evidence that under such conditions
+they are able to subsist on the starch of the wall paper, juices of
+moistened wood, or the moisture in the accumulations of dust, as is
+often stated.
+
+There are three or four generations a year, as Girault's breeding
+experiments have conclusively shown. He found that the bed-bug does not
+hibernate where the conditions are such as to allow it to breed and that
+breeding is continuous unless interrupted by the lack of food or, during
+the winter, by low temperature.
+
+Bed-bugs ordinarily crawl from their hiding places and attack the face
+and neck or uncovered parts of the legs and arms of their victims. If
+undisturbed, they will feed to repletion. We have found that the young
+nymph would glut itself in about six minutes, though some individuals
+fed continuously for nine minutes, while the adult required ten to
+fifteen minutes for a full meal. When gorged, it quickly retreats to a
+crack or crevice to digest its meal, a process which requires two or
+three days. The effect of the bite depends very greatly on the
+susceptibility of the individual attacked. Some persons are so little
+affected that they may be wholly ignorant of the presence of a large
+number of bugs. Usually the bite produces a small hard swelling, or
+wheal, whitish in color. It may even be accompanied by an edema and a
+disagreeable inflammation, and in such susceptible individuals the
+restlessness and loss of sleep due to the presence of the insects may be
+a matter of considerable importance. Stiles (1907) records the case of a
+young man who underwent treatment for neurasthenia, the diagnosis being
+agreed upon by several prominent physicians; all symptoms promptly
+disappeared, however, immediately following a thorough fumigation of
+his rooms, where nearly a pint of bed-bugs were collected.
+
+It is natural to suppose that an insect which throughout its whole life
+is in such intimate relationship with man should play an important role
+in the transmission of disease. Yet comparatively little is definitely
+known regarding the importance of the bed-bug in this respect. It has
+been shown that it is capable of transmitting the bubonic plague, and
+South American trypanosomiasis. Nuttall succeeded in transmitting
+European relapsing fever from mouse to mouse by its bite. It has been
+claimed that Oriental sore, tuberculosis, and even syphilis may be so
+carried. These phases of the subject will be considered later.
+
+The sources of infestation are many, and the invasion of a house is not
+necessarily due to neglect, though the continued presence of the pests
+is quite another matter. In apartments and closely placed houses they
+are known to invade new quarters by migration. They are frequently to be
+met with in boat and sleeper berths, and even the plush seats of day
+coaches, whence a nucleus may be carried in baggage to residences. They
+may be brought in the laundry or in clothes of servants.
+
+Usually they are a great scourge in frontier settlements and it is
+generally believed that they live in nature under the bark of trees, in
+lumber, and under similar conditions. This belief is founded upon the
+common occurrence of bugs resembling the bed-bug, in such places. As a
+matter of fact, they are no relation to bed-bugs but belong to
+plant-feeding forms alone (fig. 19 _c_, _d_).
+
+It is also often stated that bed-bugs live in poultry houses, in
+swallows nests, and on bats, and that it is from these sources that they
+gain access to dwellings. These bugs are specifically distinct from the
+true bed-bug, but any of them may, rarely, invade houses. Moreover,
+chicken houses are sometimes thoroughly infested with the true _Cimex
+lectularius_.
+
+Control measures consist in the use of iron bedsteads and the reduction
+of hiding places for the bugs. If the infestation is slight they may be
+exterminated by a vigilant and systematic hunt, and by squirting
+gasoline or alcohol into cracks and crevices of the beds, and furniture.
+Fumigation must be resorted to in more general infestations.
+
+The simplest and safest method of fumigation is by the use of flowers of
+sulphur at the rate of two pounds to each one thousand cubic feet of
+room space. The sulphur should be placed in a pan, a well made in the
+top of the pile and a little alcohol poured in, to facilitate burning.
+The whole should be placed in a larger pan and surrounded by water so as
+to avoid all danger of fire. Windows should be tightly closed, beds,
+closets and drawers opened, and bedding spread out over chairs in order
+to expose them fully to the fumes. As metal is tarnished by the sulphur
+fumes, ornaments, clocks, instruments, and the like should be removed.
+When all is ready the sulphur should be fired, the room tightly closed
+and left for twelve to twenty-four hours. Still more efficient in large
+houses, or where many hiding places favor the bugs, is fumigation with
+hydrocyanic acid gas. This is a deadly poison and must be used under
+rigid precautions. Through the courtesy of Professor Herrick, who has
+had much experience with this method, we give in the Appendix, the clear
+and detailed directions taken from his bulletin on "Household Insects."
+
+Fumigation with formaldehyde gas, either from the liquid or "solid"
+formalin, so efficient in the case of contagious diseases, is useless
+against bed-bugs and most other insects.
+
+
+OTHER BED-BUGS--_Cimex hemipterus_ (= _C. rotundatus_) is a tropical and
+subtropical species, occurring in both the old and new world. Patton and
+Cragg state that it is distributed throughout India, Burma, Assam, the
+Malay Peninsula, Aden, the Island of Mauritius, Reunion, St. Vincent and
+Porto Rico. "It is widely distributed in Africa, and is probably the
+common species associated there with man." Brumpt also records it for
+Cuba, the Antilles, Brazil, and Venezuela.
+
+This species, which is sometimes called the Indian bed-bug, differs from
+_C. lectularius_ in being darker and in having a more elongate abdomen.
+The head also is shorter and narrower, and the prothorax has rounded
+borders.
+
+It has the same habits and practically the same life cycle as _Cimex
+lectularius_. Mackie, in India, has found that it is capable of
+transmitting the Asiatic type of recurrent fever. Roger suggested that
+it was also capable of transmitting Kala-azar and Patton has described
+in detail the developmental stages of _Leishmania_, the causative
+organism of Kala-azar, in the stomach of this bug, but Brumpt declares
+that the forms described are those of a common, non-pathogenic
+flagellate to be found in the bug, and have nothing to do with the
+human disease. Brumpt has shown experimentally that _Cimex hemipterus_
+may transmit _Trypanosoma cruzi_ in its excrement.
+
+_Cimex boueti_, occurring in French Guinea, is another species attacking
+man. Its habits and general life history are the same as for the above
+species. It is 3 to 4.5 mm. in length, has vestigial elytra, and much
+elongated antennae and legs. The extended hind legs are about as long as
+the body.
+
+_Cimex columbarius_, a widely distributed species normally living in
+poultry houses and dove cotes, _C. inodorus_, infesting poultry in
+Mexico, _C. hirundinis_, occurring in the nests of swallows in Europe
+and _Oeciacus vicarius_ (fig. 19i) occurring in swallows' nests in this
+country, are species which occasionally infest houses and attack man.
+
+[Illustration: 71. Conorhinus sanguisugus.]
+
+_Conorhinus sanguisugus_, the cone-nosed bed-bug. We have seen in our
+consideration of poisonous insects, that various species of Reduviid
+bugs readily attack man. Certain of these are nocturnal and are so
+commonly found in houses that they have gained the name, of "big
+bed-bugs." The most noted of these, in the United States, is _Conorhinus
+sanguisugus_ (fig. 71), which is widely distributed in our Southern
+States.
+
+Like its near relatives, _Conorhinus sanguisugus_ is carnivorous in
+habit and feeds upon insects as well as upon mammalian and human blood.
+It is reported as often occurring in poultry houses and as attacking
+horses in barns. The life history has been worked out in considerable
+detail by Marlatt, (1902), from whose account we extract the following.
+
+[Illustration: 72. Beak of Conorhinus sanguisugus. After Marlatt.]
+
+The eggs are white, changing to yellow and pink before hatching. The
+young hatch within twenty days and there are four nymphal stages. In all
+these stages the insect is active and predaceous, the mouth-parts (fig.
+72) being powerfully developed. The eggs are normally deposited, and the
+early stages are undoubtedly passed, out of doors, the food of the
+immature forms being other insects. Immature specimens are rarely found
+indoors. It winters both in the partly grown and adult stage, often
+under the bark of trees or in any similar protection, and only in its
+nocturnal spring and early summer flights does it attack men. Marlatt
+states that this insect seems to be decidedly on the increase in the
+region which it particularly infests,--the plains region from Texas
+northward and westward. In California a closely related species of
+similar habits is known locally as the "monitor bug."
+
+The effect of the bite of the giant bed-bug on man is often very severe,
+a poisonous saliva apparently being injected into the wound. We have
+discussed this phase of the subject more fully under the head of
+poisonous insects.
+
+_Conorhinus megistus_ is a Brazilian species very commonly attacking
+man, and of special interest since Chagas has shown that it is the
+carrier of a trypanosomiasis of man. Its habits and life history have
+been studied in detail by Neiva, (1910).
+
+This species is now pre-eminently a household insect, depositing its
+eggs in cracks and crevices in houses, though this is a relatively
+recent adaptation. The nymphs emerge in from twenty to forty days,
+depending upon the temperature. There are five nymphal stages, and as in
+the case of true bed-bugs, the duration of these is very greatly
+influenced by the availability of food and by temperature. Neiva reckons
+the entire life cycle, from egg to egg, as requiring a minimum of three
+hundred and twenty-four days.
+
+The nymphs begin to suck blood in three to five days after hatching.
+They usually feed at night and in the dark, attacking especially the
+face of sleeping individuals. The bite occasions but little pain. The
+immature insects live in cracks and crevices in houses and invade the
+beds which are in contact with walls, but the adults are active flyers
+and attack people sleeping in hammocks. The males as well as the females
+are blood suckers.
+
+Like many blood-sucking forms, _Conorhinus megistus_ can endure for long
+periods without food. Neiva received a female specimen which had been
+for fifty-seven days alive in a tightly closed box. They rarely feed on
+two consecutive days, even on small quantities of blood, and were never
+seen to feed on three consecutive days.
+
+Methods of control consist in screening against the adult bugs, and the
+elimination of crevices and such hiding places of the nymphs. Where the
+infestation is considerable, fumigation with sulphur is advisable.
+
+
+PARASITIC DIPTERA OR FLIES
+
+Of the DIPTERA or two-winged flies, many species occasionally attack
+man. Of these, a few are outstanding pests, many of them may also serve
+to disseminate disease, a phase of our subject which will be considered
+later. We shall now consider the most important of the group from the
+viewpoint of their direct attacks on man.
+
+
+Psychodidae or Moth-Flies
+
+The PSYCHODIDAE or Moth-flies, include a few species which attack man,
+and at least one species, _Phlebotomus papatasii_, is known to transmit
+the so-called "three-day fever" of man. Another species is supposed to
+be the vector of Peruvian verruga.
+
+The family is made up of small, sometimes very small, nematocerous
+Diptera, which are densely covered with hairs, giving them a moth-like
+appearance. The wings are relatively large, oval or lanceolate in shape,
+and when at rest are held in a sloping manner over the abdomen, or are
+held horizontally in such a way as to give the insect a triangular
+outline. Not only is the moth-like appearance characteristic, but the
+venation of the wings (fig. 163, d) is very peculiar and, according to
+Comstock, presents an extremely generalized form. All of the
+longitudinal veins separate near the base of the wing except veins R_2
+and R_3 and veins M_1 and M_2. Cross veins are wanting in most cases.
+
+Comparatively little is known regarding the life-history and habits of
+the Psychodidae, but one genus, _Phlebotomus_, contains minute,
+blood-sucking species, commonly known as sand-flies. The family is
+divided into two subfamilies, the PSYCHODINAE and the PHLEBOTOMINAE.
+The second of these, the PHLEBOTOMINAE, is of interest to us.
+
+
+THE PHLEBOTOMINAE--The Phlebotominae differ from the Psychodinae
+in that the radical sector branches well out into the wing rather than
+at the base of the wing. They are usually less hairy than the
+Psychodinae. The ovipositor is hidden and less strongly chitinized.
+The species attacking man belong to the genus _Phlebotomus_, small forms
+with relatively large, hairy wings which are held upright, and with
+elongate proboscis. The mandibles and maxillae are serrated and fitted
+for biting.
+
+According to Miss Summers (1913) there are twenty-nine known species of
+the genus _Phlebotomus_, five European, eleven Asiatic, seven African
+and six American. One species only, _Phlebotomus vexator_, has been
+reported for the United States. This was described by Coquillett,
+(1907), from species taken on Plummer's Island, Maryland. It measures
+only 1.5 mm. in length. As it is very probable that this species is much
+more widely distributed, and that other species of these minute flies
+will be found to occur in our fauna, we quote Coquillett's description.
+
+_Phlebotomus vexator_, Coq.: Yellow, the mesonotum brown, hairs chiefly
+brown; legs in certain lights appear brown, but are covered with a white
+tomentum; wings hyaline, unmarked; the first vein (R_1) terminates
+opposite one-fifth of the length of the first submarginal cell (cell
+R_2); this cell is slightly over twice as long as its petiole; terminal,
+horny portion of male claspers slender, bearing many long hairs; the
+apex terminated by two curved spines which are more than one-half as
+long as the preceding part, and just in front of these are two similar
+spines, while near the middle of the length of this portion is a fifth
+spine similar to the others. Length 1.5 mm.
+
+The life-history of the Phlebotomus flies has been best worked out for
+the European _Phlebotomus papatasii_ and we shall briefly summarize the
+account of Doerr and Russ (1913) based primarily on work on this
+species. The European Phlebotomus flies appear at the beginning of the
+warm season, a few weeks after the cessation of the heavy rains and
+storms of springtime. They gradually become more abundant until they
+reach their first maximum, which in Italy is near the end of July
+(Grassi). They then become scarcer but reach a second maximum in
+September. At the beginning of winter they vanish completely,
+hibernating individuals not being found.
+
+After fertilization there is a period of eight to ten days before
+oviposition. The eggs are then deposited, the majority in a single mass
+covered by a slimy secretion from the sebaceous glands. The larvae emerge
+in fourteen to twenty days. There is uncertainty as to the length of
+larval life, specimens kept in captivity remaining fifty or more days
+without transforming. Growth may be much more rapid in nature. The larvae
+do not live in fluid media but in moist detritus in dark places. Marett
+believes that they live chiefly on the excrement of pill-bugs (Oniscidae)
+and lizards. Pupation always occurs during the night. The remnants of
+the larval skin remain attached to the last two segments of the
+quiescent pupa and serve to attach it to the stone on which it lives.
+The pupal stage lasts eleven to sixteen days, the adult escaping at
+night.
+
+Only the females suck blood. They attack not only man but all
+warm-blooded animals and, according to recent workers, also cold-blooded
+forms, such as frogs, lizards, and larvae. Indeed, Townsend (1914)
+believes that there is an intimate relation between _Phlebotomus_ and
+lizards, or other reptiles the world over. The Phlebotomus passes the
+daylight hours within the darkened recesses of the loose stone walls and
+piles of rock in order to escape wind and strong light. Lizards inhabit
+the same places, and the flies, always ready to suck blood in the
+absence of light and wind, have been found more prone to suck reptilian
+than mammalian blood.
+
+On hot summer nights, when the wind is not stirring, the Phlebotomus
+flies, or sand-flies, as they are popularly called, invade houses and
+sleeping rooms in swarms and attack the inmates. As soon as light begins
+to break the flies either escape to the breeding places, or cool, dark
+places protected from the wind, or a part of them remain in the rooms,
+hiding behind pictures, under garments, and in similar places. Wherever
+the Phlebotomus flies occur they are an intolerable nuisance. On account
+of their small size they can easily pass through the meshes of ordinary
+screens and mosquito curtains. They attack silently and inflict a very
+painful, stinging bite, followed by itching. The ankles, dorsum of the
+feet, wrists, inner elbow, knee joint and similar places are favorite
+places of attack, possibly on account of their more delicate skin.
+
+Special interest has been attracted to these little pests in recent
+years, since it has been shown that they transmit the European
+"pappatici fever" or "three day fever." More recently yet, it appears
+that they are the carriers of the virus of the Peruvian "verruga." This
+phase of the subject will be discussed later.
+
+Control measures have not been worked out. As Newstead says, "In
+consideration of the facts which have so far been brought to light
+regarding the economy of Phlebotomus, it is clearly evident that the
+task of suppressing these insects is an almost insurmountable one. Had
+we to deal with insects as large and as accessible as mosquitoes, the
+adoption of prophylactic measures would be comparatively easy, but owing
+to the extremely minute size and almost flea-like habits of the adult
+insects, and the enormous area over which the breeding-places may occur,
+we are faced with a problem which is most difficult of solution." For
+these reasons, Newstead considers that the only really prophylactic
+measures which can at present be taken, are those which are considered
+as precautionary against the bites of the insects.
+
+Of repellents, he cites as one of the best a salve composed of the
+following:
+
+  Ol. Anisi                                                    3 grs.
+  Ol. Eucalypti                                                3 grs.
+  Ol. Terebenth                                                3 grs.
+  Unq. Acid Borac.
+
+Of sprays he recommends as the least objectionable and at the same time
+one of the most effective, formalin. "The dark portions and angles of
+sleeping apartments should be sprayed with a one per cent. solution of
+this substance every day during the season in which the flies are
+prevalent. A fine spraying apparatus is necessary for its application
+and an excessive amount must not be applied. It is considered an
+excellent plan also to spray the mosquito curtains regularly every day
+towards sunset; nets thus treated are claimed to repel the attacks of
+these insects." This effectiveness of formalin is very surprising for,
+as we have seen, it is almost wholly ineffective against bed-bugs,
+mosquitoes, house flies and other insects, where it has been tried.
+
+A measure which promises to be very effective, where it can be adopted,
+is the use of electric fans so placed as to produce a current of air in
+the direction of the windows of sleeping apartments. On account of the
+inability of the Phlebotomus flies to withstand even slight breezes, it
+seems very probable that they would be unable to enter a room so
+protected.
+
+
+Culicidae or Mosquitoes
+
+From the medical viewpoint, probably the most interesting and important
+of the blood-sucking insects are the mosquitoes. Certainly this is true
+of temperate zones, such as those of the United States. The result is
+that no other group of insects has aroused such widespread interest, or
+has been subjected to more detailed study than have the mosquitoes,
+since their role as carriers of disease was made known. There is an
+enormous literature dealing with the group, but fortunately for the
+general student, this has been well summarized by a number of workers.
+The most important and helpful of the general works are those of Howard
+(1901), Smith (1904), Blanchard (1905), Mitchell (1907), and especially
+of Howard, Dyar, and Knab, whose magnificent monograph is still in
+course of publication.
+
+Aside from their importance as carriers of disease, mosquitoes are
+notorious as pests of man, and the earlier literature on the group is
+largely devoted to references to their enormous numbers and their
+blood-thirstiness in certain regions. They are to be found in all parts
+of the world, from the equator to the Arctic and Antarctic regions.
+Linnaeus, in the "Flora Lapponica," according to Howard, Dyar and Knab,
+"dwells at some length upon the great abundance of mosquitoes in Lapland
+and the torments they inflicted upon man and beast. He states that he
+believes that nowhere else on earth are they found in such abundance and
+he compares their numbers to the dust of the earth. Even in the open,
+you cannot draw your breath without having your mouth and nostrils
+filled with them; and ointments of tar and cream or of fish grease are
+scarcely sufficient to protect even the case-hardened cuticle of the
+Laplander from their bite. Even in their cabins, the natives cannot take
+a mouthful of food or lie down to sleep unless they are fumigated almost
+to suffocation." In some parts of the Northwestern and Southwestern
+United States it is necessary to protect horses working in the fields by
+the use of sheets or burlaps, against the ferocious attacks of these
+insects. It is a surprising fact that even in the dry deserts of the
+western United States they sometimes occur in enormous numbers.
+
+Until comparatively recent years, but few species of mosquitoes were
+known and most of the statements regarding their life-history were based
+upon the classic work of Reaumur (1738) on the biology of the rain
+barrel mosquito, _Culex pipiens_. In 1896, Dr. Howard refers to
+twenty-one species in the United States, now over fifty are known;
+Giles, in 1900, gives a total of two hundred and forty-two for the world
+fauna, now over seven hundred species are known. We have found eighteen
+species at Ithaca, N. Y.
+
+All of the known species of mosquitoes are aquatic in the larval stage,
+but in their life-histories and habits such great differences occur that
+we now know that it is not possible to select any one species as typical
+of the group. For our present purpose we shall first discuss the general
+characteristics and structure of mosquitoes, and shall then give the
+life-history of a common species, following this by a brief
+consideration of some of the more striking departures from what have
+been supposed to be the typical condition.
+
+The CULICIDAE are slender, nematocerous Diptera with narrow wings,
+antennae plumose in the males, and usually with the proboscis much longer
+than the head, slender, firm and adapted for piercing in the female.
+The most characteristic feature is that the margins of the wings and, in
+most cases, the wing veins possess a fringe of scale-like hairs. These
+may also cover in part, or entirely, the head, thorax, abdomen and legs.
+The females, only, suck blood.
+
+On account of the importance of the group in this country and the
+desirability of the student being able to determine material in various
+stages, we show in the accompanying figures the characters most used in
+classification.
+
+The larvae (fig. 73) are elongate, with the head and thorax sharply
+distinct. The larval antennae are prominent, consisting of a single
+cylindrical and sometimes curved segment. The outer third is often
+narrower and bears at its base a fan-shaped tuft of hairs, the
+arrangement and abundance of which is of systematic importance. About
+the mouth are the so-called rotary mouth brushes, dense masses of long
+hairs borne by the labrum and having the function of sweeping food into
+the mouth. The form and arrangement of thoracic, abdominal, and anal
+tufts of hair vary in different species and present characteristics of
+value. On either side of the eighth abdominal segment is a patch of
+scales varying greatly in arrangement and number and of much value in
+separating species. Respiration is by means of tracheae which open at the
+apex of the so-called anal siphon, when it is present. In addition,
+there are also one or two pairs of tracheal gills which vary much in
+appearance in different species. On the ventral side of the anal siphon
+is a double row of flattened, toothed spines whose number and shape are
+likewise of some value in separating species. They constitute the comb
+or pecten.
+
+[Illustration: 73. Culex larva showing details of external structure.]
+
+The pupa (fig. 139, b) unlike that of most insects, is active, though it
+takes no food. The head and thorax are not distinctly separated, but the
+slender flexible abdomen in sharply marked off. The antennae,
+mouth-parts, legs, and wings of the future adult are now external, but
+enclosed in chitinous cases. On the upper surface, near the base of the
+wings are two trumpets, or breathing tubes, for the pupal spiracles are
+towards the anterior end instead of at the caudal end, as in the larva.
+At the tip of the abdomen is a pair of large chitinous swimming paddles.
+
+As illustrative of the life cycle of a mosquito we shall discuss the
+development of a common house mosquito, _Culex pipiens_, often referred
+to in the Northern United States as the rain barrel mosquito. Its life
+cycle is often given as typical for the entire group, but, as we have
+already emphasized, no one species can serve this purpose.
+
+The adults of _Culex pipiens_ hibernate throughout the winter in
+cellars, buildings, hollow trees, or similar dark shelters. Early in the
+spring they emerge and deposit their eggs in a raft-like mass. The
+number of eggs in a single mass is in the neighborhood of two hundred,
+recorded counts varying considerably. A single female may deposit
+several masses during her life time. The duration of the egg stage is
+dependent upon temperature. In the warm summer time the larvae may emerge
+within a day. The larvae undergo four molts and under optimum conditions
+may transform into pupae in about a week's time. Under the same favorable
+conditions, the pupal stage may be completed in a day's time. The total
+life cycle of _Culex pipiens_, under optimum conditions, may thus be
+completed in a week to ten days. This period may be considerably
+extended under less favorable conditions of temperature and food supply.
+
+_Culex pipiens_ breeds continuously throughout the summer, developing in
+rain barrels, horse troughs, tin cans, or indeed in any standing water
+about houses, which lasts for a week or more. The catch basins of sewers
+furnish an abundant supply of the pests under some conditions. Such
+places, the tin gutters on residences, and all possible breeding places
+must be considered in attempts to exterminate this species.
+
+Other species of mosquitoes may exhibit radical departures from _Culex
+pipiens_ in life-history and habits. To control them it is essential
+that the biological details be thoroughly worked out for, as Howard,
+Dyar, and Knab have emphasized, "much useless labor and expense can be
+avoided by an accurate knowledge of the habits of the species." For a
+critical discussion of the known facts the reader is referred to their
+monograph. We shall confine ourselves to a few illustrations.
+
+The majority of mosquitoes in temperate climates hibernate in the egg
+stage, hatching in the spring or even mild winter days in water from
+melting snow. It is such single-brooded species which appear in
+astounding numbers in the far North. Similarly, in dry regions the eggs
+may stand thorough dessication, and yet hatch out with great promptness
+when submerged by the rains. "Another provision to insure the species
+against destruction in such a case, exists in the fact * * * that not
+all the eggs hatch, a part of them lying over until again submerged by
+subsequent rains." In temperate North America, a few species pass the
+winter in the larval state. An interesting illustration of this is
+afforded by _Wyeomia smithii_, whose larvae live in pitcher plants and
+are to be found on the coldest winter days imbedded in the solid ice.
+Late in the spring, the adults emerge and produce several broods during
+the summer.
+
+In the United States, one of the most important facts which has been
+brought out by the intensive studies of recent years is that certain
+species are migratory and that they can travel long distances and become
+an intolerable pest many miles from their breeding places. This was
+forcibly emphasized in Dr. Smith's work in New Jersey, when he found
+that migratory mosquitoes, developing in the salt marshes along the
+coast, are the dominant species largely responsible for the fame of the
+New Jersey mosquito. The species concerned are _Aedes sollicitans_, _A.
+cantator_ and _A. taeniorhynchus_. Dr. Smith decided that the first of
+these might migrate at least forty miles inland. It is obvious that
+where such species are the dominant pest, local control measures are a
+useless waste of time and money. Such migratory habits are rare,
+however, and it is probable that the majority of mosquitoes do not fly
+any great distance from their breeding places.
+
+While mosquitoes are thought of primarily as a pest of man, there are
+many species which have never been known to feed upon human or mammalian
+blood, no matter how favorable the opportunity. According to Howard,
+Dyar, and Knab, this is true of _Culex territans_, one of the common
+mosquitoes in the summer months in the Northern United States. There are
+some species, probably many, in which the females, like the males, are
+plant feeders. In experimental work, both sexes are often kept alive for
+long periods by feeding them upon ripe banana, dried fig, raisins, and
+the like, and in spite of sweeping assertions that mosquitoes must have
+a meal of blood in order to stimulate the ovaries to development, some
+of the common blood-sucking species, notably _Culex pipiens_, have been
+bred repeatedly without opportunity to feed upon blood.
+
+The effect of the bite varies greatly with different species and depends
+upon the susceptibility of the individual bitten. Some persons are
+driven almost frantic by the attacks of the pests when their companions
+seem almost unconscious of any inconvenience. Usually, irritation and
+some degree of inflammation appear shortly following the bite. Not
+infrequently a hardened wheal or even a nodule forms, and sometimes
+scratching leads to secondary infection and serious results.
+
+The source of the poison is usually supposed to be the salivary glands
+of the insect. As we have already pointed out, (p. 34), Macloskie
+believed that one lobe of the gland, on each side, was specialized for
+forming the poison, while a radically different view is that of
+Schaudinn, who believed that the irritation is due to the expelled
+contents of the oesophageal diverticula, which contain a gas and a
+peculiar type of fungi or bacteria. In numerous attempts, Schaudinn was
+unable to produce any irritation by applying the triturated salivary
+glands to a wound, but obtained the typical result when he used the
+isolated diverticula.
+
+The irritation of the bite may be relieved to some extent by using
+ammonia water, a one per cent. alcoholic solution of menthol, or
+preparations of cresol, or carbolic acid. Dr. Howard recommends rubbing
+the bite gently with a piece of moist toilet soap. Castellani and
+Chalmers recommend cleansing inflamed bites with one in forty carbolic
+lotion, followed by dressing with boracic ointment. Of course,
+scratching should be avoided as much as possible.
+
+Repellents of various kinds are used, for warding off the attacks of the
+insects. We have often used a mixture of equal parts of oil of
+pennyroyal and kerosene, applied to the hands and face. Oil of
+citronella is much used and is less objectionable to some persons. A
+recommended formula is, oil of citronella one ounce, spirits of camphor
+one ounce, oil of cedar one-half ounce. A last resort would seem to be
+the following mixture recommended by Howard, Dyar, and Knab for use by
+hunters and fishermen in badly infested regions, against mosquitoes and
+blackflies.
+
+Take 2-1/4 lbs. of mutton tallow and strain it. While still hot add 1/2
+lb. black tar (Canadian tar). Stir thoroughly and pour into the
+receptacle in which it is to be contained. When nearly cool stir in
+three ounces of oil of citronella and 1-1/4 oz. of pennyroyal.
+
+At night the surest protection is a good bed net. There are many types
+of these in use, but in order to be serviceable and at the same time
+comfortable it should be roomy and hung in such a way as to be stretched
+tightly in every direction. We prefer one suspended from a broad, square
+frame, supported by a right-angled standard which is fastened to the
+head of the bed. It must be absolutely free from rents or holes and
+tucked in securely under the mattress or it will serve merely as a
+convenient cage to retain mosquitoes which gain an entrance. While such
+nets are a convenience in any mosquito ridden community, they are
+essential in regions where disease-carrying species abound. Screening of
+doors, windows and porches, against the pests is so commonly practiced
+in this country that its importance and convenience need hardly be
+urged.
+
+Destruction of mosquitoes and prevention of breeding are of fundamental
+importance. Such measures demand first, as we have seen, the correct
+determination of the species which is to be dealt with, and a knowledge
+of its life-history and habits. If it prove to be one of the migratory
+forms, it is beyond mere local effort and becomes a problem demanding
+careful organization and state control. An excellent illustration of the
+importance and effectiveness of work along these lines is afforded by
+that in New Jersey, begun by the late Dr. John B. Smith and being pushed
+with vigor by his successor, Dr. Headlee.
+
+In any case, there is necessity for community action. Even near the
+coast, where the migratory species are dominant, there are the local
+species which demand attention and which cannot be reached by any
+measures directed against the species of the salt marshes. The most
+important of local measures consist in the destruction of breeding
+places by filling or draining ponds and pools, clearing up of more
+temporary breeding places, such as cans, pails, water barrels and the
+like. Under conditions where complete drainage of swamps is
+impracticable or undesirable, judicious dredging may result in a pool or
+series of steep-sided pools deep enough to maintain a supply of fish,
+which will keep down the mosquito larvae. Where water receptacles are
+needed for storage of rain water, they should be protected by careful
+screening or a film of kerosene over the top of the water, renewed every
+two weeks or so, so as to prevent mosquitoes from depositing their eggs.
+When kerosene is used, Water drawn from the bottom of the receptacle
+will not be contaminated by it to any injurious extent. Where ponds
+cannot be drained much good will be accomplished by spraying kerosene
+oil on the surface of the water, or by the introduction of fish which
+will feed on the larvae.
+
+Detailed consideration of the most efficient measures for controlling
+mosquitoes is to be found in Dr. Howard's Bulletin No. 88 of the Bureau
+of Entomology, "Preventive and remedial work against mosquitoes" or, in
+more summarized form, in Farmers' Bulletin No. 444. One of these should
+be obtained by any person interested in the problems of mosquito control
+and public health.
+
+[Illustration: 74. Mouth parts of Simulium. After Grunberg.]
+
+
+The Simuliidae, or Black Flies
+
+The SIMULIIDAE, or black flies, are small, dark, or black flies, with a
+stout body and a hump-back appearance. The antennae are short but
+eleven-segmented, the wings broad, without scales or hairs, and with the
+anterior veins stout but the others very weak. The mouth-parts (fig. 74)
+are fitted for biting.
+
+The larvae of the Simuliidae (fig. 75) are aquatic and, unlike those of
+mosquitoes, require a well aerated, or swiftly running water. Here they
+attach to stones, logs, or vegetation and feed upon various
+micro-organisms. They pupate in silken cocoons open at the top. Detailed
+life-histories have not been worked out for most of the species. We
+shall consider as typical that of _Simulium pictipes_, an inoffensive
+species widely distributed in the Eastern United States, which has been
+studied especially at Ithaca, N.Y. (Johannsen, 1903).
+
+[Illustration: 75. Larva of Simulium, (x8). After Garman.]
+
+The eggs are deposited in a compact yellowish layer on the surface of
+rock, on the brinks of falls and rapids where the water is flowing
+swiftly. They are elongate ellipsoidal in shape, about .4 by .18 mm. As
+myriads of females deposit in the same place the egg patches may be
+conspicuous coatings of a foot or much more in diameter. When first laid
+they are enveloped in a yellowish white slime, which becomes darker,
+until finally it becomes black just before the emerging of the larvae.
+The egg stage lasts a week.
+
+The larvae (fig. 75) are black, soft skinned, somewhat cylindrical in
+shape, enlarged at both ends and attenuated in the middle. The posterior
+half is much stouter than the anterior part and almost club-shaped. The
+head bears two large fan-shaped organs which aid in procuring food.
+Respiration is accomplished by means of three so-called blood gills
+which are pushed out from the dorsal part of the rectum. The larvae occur
+in enormous numbers, in moss-like patches. If removed from their natural
+habitat and placed in quiet water they die within three or four hours.
+Fastened to the rock by means of a disk-like sucker at the caudal end of
+the body, they ordinarily assume an erect position. They move about on
+the surface of the rocks, to a limited extent, with a looping gait
+similar to that of a measuring worm, and a web is secreted which
+prevents their being washed away by the swiftly flowing water. They feed
+chiefly upon algae and diatoms.
+
+The complete larval stage during the summer months occupies about four
+weeks, varying somewhat with the temperature and velocity of the water.
+At the end of this period they spin from cephalic glands, boot-shaped
+silken cocoons within which they pupate. The cocoon when spun is firmly
+attached to the rock and also to adjacent cocoons. Clustered
+continuously over a large area and sometimes one above another, they
+form a compact, carpet-like covering on the rocks, the reddish-brown
+color of which is easily distinguishable from the jet-black appearance
+of the larvae. The pupal stage lasts about three weeks. The adult fly,
+surrounded by a bubble of air, quickly rises to the surface of the water
+and escapes. The adults (fig. 76) are apparently short lived and thus
+the entire life cycle, from egg to egg is completed in approximately
+eight weeks.
+
+[Illustration: 76. Simulium venustum, (x8). After Garman.]
+
+In the case of _Simulium pictipes_ at Ithaca, N. Y., the first brood of
+adults emerges early in May and successive generations are produced
+throughout the summer and early autumn. This species winters in the
+larval condition. Most of the other species of _Simulium_ which have
+been studied seem to be single brooded.
+
+While _Simulium pictipes_ does not attack man, there are a number of the
+species which are blood-sucking and in some regions they are a veritable
+scourge. In recent years the greatest interest in the group has been
+aroused by Sambon's hypothesis that they transmit pellagra from man to
+man. This has not been established, and, indeed, seems very doubtful,
+but the importance of these insects as pests and the possibility that
+they may carry disease make it urgent that detailed life-histories of
+the hominoxious species be worked out.
+
+As pests a vivid account of their attacks is in Agassiz's "Lake
+Superior" (p. 61), quoted by Forbes (1912).
+
+"Neither the love of the picturesque, however, nor the interests of
+science, could tempt us into the woods, so terrible were the black
+flies. This pest of flies which all the way hither had confined our
+ramblings on shore pretty closely to the rocks and the beach, and had
+been growing constantly worse, here reached its climax. Although
+detained nearly two days, * * * we could only sit with folded hands, or
+employ ourselves in arranging specimens, and such other operations as
+could be pursued in camp, and under the protection of a 'smudge.' One,
+whom scientific ardor tempted a little way up the river in a canoe,
+after water plants, came back a frightful spectacle, with blood-red
+rings round his eyes, his face bloody, and covered with punctures. The
+next morning his head and neck were swollen as if from an attack of
+erysipelas."
+
+There are even well authenticated accounts on record of death of humans
+from the attacks of large swarms of these gnats. In some regions, and
+especially in the Mississippi Valley in this country, certain species of
+black flies have been the cause of enormous losses to farmers and
+stockmen, through their attacks on poultry and domestic animals. C. V.
+Riley states that in 1874 the loss occasioned in one county in Tennessee
+was estimated at $500,000.
+
+The measures of prevention and protection against these insects have
+been well summarized by Forbes (1912). They are of two kinds: "the use
+of repellents intended to drive away the winged flies, and measures for
+the local destruction of the aquatic larvae. The repellents used are
+either smudges, or surface applications made to keep the flies from
+biting. The black-fly will not endure a dense smoke, and the well-known
+mosquito smudge seems to be ordinarily sufficient for the protection of
+man. In the South, leather, cloth, and other materials which will make
+the densest and most stifling smoke, are often preserved for this use in
+the spring. Smudges are built in pastures for the protection of stock,
+and are kept burning before the doors of barns and stables. As the
+black-flies do not readily enter a dark room, light is excluded from
+stables as much as possible during the gnat season. If teams must be
+used in the open field while gnats are abroad, they may be protected
+against the attacks of the gnats by applying cotton-seed oil or axle
+grease to the surface, especially to the less hairy parts of the
+animals, at least twice a day. A mixture of oil and tar and, indeed,
+several other preventives, are of practical use in badly infested
+regions; but no definite test or exact comparison has been made with any
+them in a way to give a record of the precise results."
+
+"It is easy to drive the flies from houses or tents by burning pyrethrum
+powder inside; this either kills the flies or stupifies them so that
+they do not bite for some time thereafter." * * * "Oil of tar is
+commonly applied to the exposed parts of the body for the purpose of
+repelling the insects, and this preparation is supplied by the Hudson
+Bay Company to its employees. Minnesota fishermen frequently grease
+their faces and hands with a mixture of kerosene and mutton tallow for
+the same purpose." We have found a mixture of equal parts of kerosene
+and oil of pennyroyal efficient.
+
+Under most circumstances very little can be done to destroy this insect
+in its early stage, but occasionally conditions are such that a
+larvicide can be used effectively. Weed (1904), and Sanderson (1910)
+both report excellent results from the use of phinotas oil, a
+proprietary compound. The first-mentioned also found that in some places
+the larvae could be removed by sweeping them loose in masses with stiff
+stable brooms and then catching them downstream on wire netting
+stretched in the water.
+
+
+Chironomidae or Midges
+
+The flies of this family, commonly known as midges, resemble mosquitoes
+in form and size but are usually more delicate, and the wing-veins,
+though sometimes hairy, are not fringed with scales. The venation is
+simpler than in the mosquitoes and the veins are usually less distinct.
+
+These midges, especially in spring or autumn, are often seen in immense
+swarms arising like smoke over swamps and producing a humming noise
+which can be heard for a considerable distance. At these seasons they
+are frequently to be found upon the windows of dwellings, where they are
+often mistaken for mosquitoes.
+
+The larvae are worm-like, but vary somewhat in form in the different
+genera. Most of them are aquatic, but a few live in the earth, in
+manure, decaying wood, under bark, or in the sap of trees, especially in
+the sap which collects in wounds.
+
+[Illustration: 77. Culicoides guttipennis; (_a_) adult, (x15); (_b_)
+head of same; (_c_) larva; (_d_) head; (_e_) pupa. After Pratt.]
+
+Of the many species of CHIRONOMIDAE, (over eight hundred known), the vast
+majority are inoffensive. The sub-family Ceratopogoninae, however, forms
+an exception, for some of the members of this group, known as sandflies,
+or punkies, suck blood and are particularly troublesome in the
+mountains, along streams, and at the seashore. Most of these have been
+classed under the genus _Ceratopogon_, but the group has been broken up
+into a number of genera and _Ceratopogon_, in the strict sense, is not
+known to contain any species which sucks the blood of vertebrates.
+
+THE CERATOPOGONINAE--The Ceratopogoninae are among the smallest of the
+Diptera, many of them being hardly a millimeter long and some not even
+so large. They are Chironomidae in which the thorax is not prolonged over
+the head. The antennae are filiform with fourteen (rarely thirteen)
+segments in both sexes, those of the male being brush-like. The basal
+segment is enlarged, the last segment never longer than the two
+preceding combined, while the last five are sub-equal to, or longer than
+the preceding segment. The legs are relatively stouter than in the other
+Chironomidae. The following three genera of this subfamily are best known
+as blood suckers in this country.
+
+Of the genus _Culicoides_ there are many species occurring in various
+parts of the world. A number are known to bite man and animals and it is
+probable that all are capable of inflicting injury. In some localities
+they are called punkies, in others, sand-flies, a name sometimes also
+applied to the species of _Simulium_ and _Phlebotomus_. Owing to their
+very small size they are known by some tribes of Indians as No-see-ums.
+The larvae are found in ponds, pools, water standing in hollow tree
+stumps, and the like. Though probably living chiefly in fresh water, we
+have found a species occurring in salt water. The larvae are small,
+slender, legless, worm-like creatures (fig. 77_c_) with small brown head
+and twelve body segments. The pupae (fig. 77_e_) are slender, more
+swollen at the anterior end and terminating in a forked process. They
+float nearly motionless in a vertical position, the respiratory tubes in
+contact with the surface film. The adults are all small, rarely
+exceeding 2-1/4 mm. in length. The wings are more or less covered with
+erect setulae or hairs and in many species variously spotted and marked
+with iridescent blotches. The antennae have fourteen segments, the palpi
+usually five. The wing venation and mouth-parts are shown in figures 77
+and 78. Of the twenty or more species of this genus occurring in the
+United States the following are known to bite: _C. cinctus_, _C.
+guttipennis_, _C. sanguisuga_, _C. stellifer_, _C. variipennis_, _C.
+unicolor_.
+
+[Illustration: 78. Culicoides guttipennis; mouth parts of adult. After
+Pratt.]
+
+One of the most widely distributed and commonest species in the Eastern
+States is _C. guttipennis_ (fig. 77a). It is black with brown legs, a
+whitish ring before the apex of each femur and both ends of each tibia;
+tarsi yellow, knobs of halteres yellow. Mesonotum opaque, brown, two
+vittae in the middle, enlarging into a large spot on the posterior half,
+also a curved row of three spots in front of each wing, and the narrow
+lateral margins, light gray pruinose. Wings nearly wholly covered with
+brown hairs, gray, with markings as shown in the figure. Length one mm.
+
+_Johannseniella_ Will. is a wide-spread genus related to the foregoing.
+Its mouth-parts are well adapted for piercing and it is said to be a
+persistent blood sucker, particularly in Greenland. This genus is
+distinguished from _Culicoides_ by its bare wings, the venation (fig.
+163, c), and the longer tarsal claws. There are over twenty North
+American species.
+
+[Illustration: 79. Chrysops univittatus, (x4). After Osborn.]
+
+In the Southwestern United States, _Tersesthes torrens_ Towns. occurs, a
+little gnat which annoys horses, and perhaps man also, by its bite. It
+is related to _Culicoides_ but differs in the number of antennal
+segments and in its wing venation (fig. 163, e). The fly measures but
+two mm. in length and is blackish in color. The antennae of the female
+have thirteen segments, the palpi but three, of which the second is
+enlarged and swollen.
+
+
+Tabanidae or Horse-Flies
+
+The TABANIDAE,--horse-flies, ear-flies, and deer-flies,--are well-known
+pests of cattle and horses and are often extremely annoying to man. The
+characteristics of the family and of the principal North American genera
+are given in the keys of Chapter XII. There are over 2500 recorded
+species. As in the mosquitoes, the females alone are blood suckers. The
+males are flower feeders or live on plant juices. This is apparently
+true also of the females of some of the genera.
+
+The eggs are deposited in masses on water plants or grasses and sedges
+growing in marshy or wet ground. Those of a common species of _Tabanus_
+are illustrated in figure 80, _a_. They are placed in masses of several
+hundred, light colored when first deposited but turning black. In a week
+or so the cylindrical larvae, tapering at both ends (fig. 80, _b_),
+escape to the water, or damp earth, and lead an active, carnivorous
+life, feeding mainly on insect larvae, and worms. In the forms which have
+been best studied the larval life is a long one, lasting for months or
+even for more than a year. Until recently, little was known concerning
+the life-histories of this group, but the studies of Hart (1895), and
+Hine (1903 +) have added greatly to the knowledge concerning North
+American forms.
+
+Many of the species attack man with avidity and are able to inflict
+painful bites, which may smart for hours. In some instances the wound is
+so considerable that blood will continue to flow after the fly has left.
+We have seen several cases of secondary infection following such bites.
+
+[Illustration: 80. (_a_) Eggs of Tabanus. Photograph by J. T. Lloyd.]
+
+[Illustration: 80. (_b_) Larva of Tabanus. Photograph by M. V. S.]
+
+The horse-flies have been definitely convicted of transferring the
+trypanosome of surra from diseased to healthy animals and there is good
+evidence that they transfer anthrax. The possibility of their being
+important agents in the conveyal of human diseases should not be
+overlooked. Indeed, Leiper has recently determined that a species of
+_Chrysops_ transfers the blood parasite _Filaria diurna_.
+
+
+Leptidae or Snipe-Flies
+
+The family LEPTIDAE is made up of moderate or large sized flies,
+predaceous in habit. They are sufficiently characterized in the keys of
+Chapter XII. Four blood-sucking species belonging to three genera have
+been reported. Of these _Symphoromyia pachyceras_ is a western species.
+Dr. J. C. Bradley, from personal experience, reports it as a vicious
+biter.
+
+[Illustration: 80. (_c_) Mouth parts of Tabanus. After Grunberg.]
+
+
+Oestridae or Bot-flies
+
+To the family OESTRIDAE belong the bot and warble-flies so frequently
+injurious to animals. The adults are large, or of medium size, heavy
+bodied, rather hairy, and usually resemble bees in appearance.
+
+The larvae live parasitically in various parts of the body of mammals,
+such as the stomach (horse bot-fly), the subcutaneous connective tissue
+(warble-fly of cattle), or the nasal passage (sheep bot-fly or head
+maggot).
+
+There are on record many cases of the occurrence of the larvae of
+Oestridae as occasional parasites of man. A number of these have been
+collected and reviewed in a thesis by Mme. Petrovskaia (1910). The
+majority of them relate to the following species.
+
+_Gastrophilus haemorrhoidalis_, the red tailed bot-fly, is one of the
+species whose larvae are most commonly found in the stomach of the horse.
+Schoch (1877) cites the case of a woman who suffered from a severe case
+of chronic catarrh of the stomach, and who vomited, and also passed from
+the anus, larvae which apparently belonged to this species. Such cases
+are exceedingly rare but instances of subcutaneous infestation are
+fairly numerous. In the latter type these larvae are sometimes the cause
+of the peculiar "creeping myasis." This is characterized at its
+beginning by a very painful swelling which gradually migrates, producing
+a narrow raised line four to twenty-five millimeters broad. When the
+larva is mature, sometimes after several months, it becomes stationary
+and a tumor is formed which opens and discharges the larva along with
+pus and serum.
+
+_Gastrophilus equi_ is the most widespread and common of the horse
+bot-flies. Portschinsky reports it as commonly causing subcutaneous
+myasis of man in Russia.
+
+_Hypoderma bovis_ (= _Oestrus bovis_), and _Hypoderma lineata_ are the
+so-called warble-flies of cattle. The latter species is the more common
+in North America but Dr. C. G. Hewitt has recently shown that _H. bovis_
+also occurs. Though warbles are very common in cattle in this country,
+the adult flies are very rarely seen. They are about half an inch in
+length, very hairy, dark, and closely resemble common honey-bees.
+
+They deposit their eggs on the hairs of cattle and the animals in
+licking themselves take in the young larvae. These pass out through the
+walls of the oesophagus and migrate through the tissues of the animal,
+to finally settle down in the subcutaneous tissue of the back. The
+possibility of their entering directly through the skin, especially in
+case of infestation of man, is not absolutely precluded, although it is
+doubtful.
+
+For both species of _Hypoderma_ there are numerous cases on record of
+their occurrence in man. Hamilton (1893) saw a boy, six years of age,
+who had been suffering for some months from the glands on one side of
+his neck being swollen and from a fetid ulceration around the back teeth
+of the lower jaw of the same side. Three months' treatment was of no
+avail and the end seemed near; one day a white object, which was seen to
+move, was observed in the ulcer at the root of the tongue, and on being
+extracted was recognized as a full grown larva of _Hypoderma_. It was of
+usual tawny color, about half an inch long when contracted, about one
+third that thickness, and quite lively. The case resulted fatally. The
+boy had been on a dairy farm the previous fall, where probably the egg
+(or larva) was in some way taken into his mouth, and the larva found
+between the base of the tongue and the jaw suitable tissue in which to
+develop.
+
+Topsent (1901) reports a case of "creeping myasis" caused by _H.
+lineata_ in the skin of the neck and shoulders of a girl eight years of
+age. The larva travelled a distance of nearly six and a half inches. The
+little patient suffered excruciating pain in the place occupied by the
+larva.
+
+_Hypoderma diana_ infests deer, and has been known to occur in man.
+
+_Oestris ovis_, the sheep bot-fly, or head maggot, is widely distributed
+in all parts of the world. In mid-summer the flies deposit living
+maggots in the nostrils of sheep. These larvae promptly pass up the nasal
+passages into the frontal and maxillary sinuses, where they feed on the
+mucous to be found there. In their migrations they cause great
+irritation to their host, and when present in numbers may cause vertigo,
+paroxysms, and even death. Portschinsky in an important monograph on
+this species, has discussed in detail its relation to man. He shows that
+it is not uncommon for the fly to attack man and that the minute living
+larvae are deposited in the eyes, nostrils, lips, or mouth. A typical
+case in which the larvae were deposited in the eye was described by a
+German oculist Kayser, in 1905. A woman brought her six year old
+daughter to him and said that the day before, about noontime, a flying
+insect struck the eye of the child and that since then she had felt a
+pain which increased towards evening. In the morning the pain ceased but
+the eye was very red. She was examined at about noon, at which time she
+was quiet and felt no pain. She was not sensitive to light, and the only
+thing noticed was a slight congestion and accumulation of secretion in
+the corner of the right eye. A careful examination of the eye disclosed
+small, active, white larvae that crawled out from the folds of the
+conjunctiva and then back and disappeared. Five of these larvae were
+removed and although an uncomfortable feeling persisted for a while, the
+eye became normal in about three weeks.
+
+Some of the other recorded cases have not resulted so favorably, for the
+eyesight has been seriously affected or even lost.
+
+According to Edmund and Etienne Sergent (1907), myasis caused by the
+larvae of _Oestris ovis_ is very common among the shepherds in Algeria.
+The natives say that the fly deposits its larvae quickly, while on the
+wing, without pause. The greatest pain is caused when these larvae
+establish themselves in the nasal cavities. They then produce severe
+frontal headaches, making sleep impossible. This is accompanied by
+continuous secretion from the nasal cavities and itching pains in the
+sinuses. If the larvae happen to get into the mouth, the throat becomes
+inflamed, swallowing is painful, and sometimes vomiting results. The
+diseased condition may last for from three to ten days or in the case of
+nasal infection, longer, but recovery always follows. The natives remove
+the larvae from the eye mechanically by means of a small rag. When the
+nose is infested, tobacco fumigations are applied, and in case of throat
+infestation gargles of pepper, onion, or garlic extracts are used.
+
+_Rhinoestrus nasalis_, the Russian gad-fly, parasitizes the
+nasopharyngeal region of the horse. According to Portschinsky, it not
+infrequently attacks man and then, in all the known cases deposits its
+larvae in the eye, only. This is generally done while the person is
+quiet, but not during sleep. The fly strikes without stopping and
+deposits its larva instantaneously. Immediately after, the victim
+experiences lancinating pains which without intermission increase in
+violence. There is an intense conjunctivitis and if the larvae are not
+removed promptly the envelopes of the eye are gradually destroyed and
+the organ lost.
+
+[Illustration: 81. Larvae of Dermatobia cyaniventris. After Blanchard.]
+
+[Illustration: 82. Young larva of Dermatobia cyaniventris. After
+Surcouf.]
+
+_Dermatobia cyaniventris_--This fly (fig. 83) is widely distributed
+throughout tropical America, and in its larval stage is well known as a
+parasite of man. The larvae (figs. 81 and 82) which are known as the "ver
+macaque," "torcel," "ver moyocuil" or by several other local names,
+enter the skin and give rise to a boil-like swelling, open at the top,
+and comparable with the swelling produced by the warble fly larvae, in
+cattle. They cause itching and occasional excruciating pain. When
+mature, nearly an inch in length, they voluntarily leave their host,
+drop to the ground and complete their development. The adult female is
+about 12 mm. in length. The face is yellow, the frons black with a
+grayish bloom; antennae yellow, the third segment four times as long as
+the second, the arista pectinate. The thorax is bluish black with
+grayish bloom; the abdomen depressed, brilliant metallescent blue with
+violet tinge. The legs are yellowish, the squamae and wings brownish.
+
+The different types of larvae represented in figure 81 were formerly
+supposed to belong to different species but Blanchard regards them as
+merely various stages of the same species. It is only very recently that
+the early stage and the method by which man becomes infested were made
+known.
+
+[Illustration: 83. Dermatobia cyaniventris (x1-3/4). After Manson.]
+
+[Illustration: 84. Mosquito carrying eggs of Dermatobia cyaniventris.
+After Surcouf.]
+
+About 1900, Blanchard observed the presence of packets of large-sized
+eggs under the abdomen of certain mosquitoes from Central America; and
+in 1910, Dr. Morales, of Costa Rica, declared that the Dermatobia
+deposited its eggs directly under the abdomen of the mosquito and that
+they were thus carried to vertebrates. Dr. Nunez Tovar observed the
+mosquito carriers of the eggs and placing larvae from this source on
+animals, produced typical tumors and reared the adult flies. It remained
+for Surcouf (1913) to work out the full details. He found that the
+Dermatobia deposits its eggs in packets covered by a very viscid
+substance, on leaves. These become attached to mosquitoes of the species
+_Janthinosoma lutzi_ (fig. 84) which walk over the leaves. The eggs
+which adhere to the abdomen, remain attached and are thus transported.
+The embryo develops, but the young larva (fig. 82) remains in the egg
+until it has opportunity to drop upon a vertebrate fed upon by the
+mosquito.
+
+
+Muscidae
+
+The following MUSCIDAE, characterized elsewhere, deserve special mention
+under our present grouping of parasitic species. Other important species
+will be considered as facultative parasites.
+
+_Stomoxys calcitrans_, the stable-fly, or the biting house-fly, is often
+confused with _Musca domestica_ and therefore is discussed especially in
+our consideration of the latter species as an accidental carrier of
+disease. Its possible relation to the spread of infantile paralysis is
+also considered later.
+
+The _tsetse flies_, belonging to the genus _Glossina_, are African
+species of blood-sucking Muscidae which have attracted much attention
+because of their role in transmitting various trypanosome diseases of
+man and animals. They are characterized in Chapter XII and are also
+discussed in connection with the diseases which they convey.
+
+_Chrysomyia macellaria_, (= _Compsomyia_), the "screw worm"-fly is one
+of the most important species of flies directly affecting man, in North
+America. It is not normally parasitic, however, and hence will be
+considered with other facultative parasites in Chapter IV.
+
+[Illustration: 85. Larva of Auchmeromyia luteola. After Graham-Smith.]
+
+[Illustration: 86. Auchmeromyia luteola (x4). After Graham-Smith.]
+
+_Auchmeromyia luteola_, the Congo floor maggot. This is a muscid of
+grewsome habits, which has a wide distribution throughout Africa. The
+fly (fig. 86) deposits its eggs on the ground of the huts of the
+natives. The whitish larvae (fig. 85) on hatching are slightly flattened
+ventrally, and each segment bears posteriorly three foot-pads
+transversely arranged. At night the larvae find their way into the low
+beds or couches of the natives and suck their blood. The adult flies do
+not bite man and, as far as known, the larvae do not play any role in the
+transmission of sleeping sickness or other diseases.
+
+This habit of blood-sucking by muscid larvae is usually referred to as
+peculiar to _Auchmeromyia luteola_ but it should be noted that the larvae
+of _Protocalliphora_ frequent the nests of birds and feed upon the
+young. Mr. A. F. Coutant has studied especially the life-history and
+habits of _P. azurea_, whose larvae he found attacking young crows at
+Ithaca, N.Y. He was unable to induce the larvae to feed on man.
+
+[Illustration: 87. Cordylobia anthropophaga (x3). After Fulleborn.]
+
+[Illustration: 88. Larva of Cordylobia anthropophaga. After Blanchard.]
+
+_Cordylobia anthropophaga_, (_Ochromyia anthropophaga_), or Tumbu-fly
+(fig. 87) is an African species whose larvae affect man much as do those
+of _Dermatobia cyniventris_, of Central and South America. The larva
+(fig. 88), which is known as "ver du Cayor" because it was first
+observed in Cayor, in Senegambia, develops in the skin of man and of
+various animals, such as dogs, cats, and monkeys. It is about 12 mm. in
+length, and of the form of the larvae of other muscids. Upon the
+intermediate segments are minute, brownish recurved spines which give to
+the larva its characteristic appearance. The life-history is not
+satisfactorily worked out, but Fuller (1914), after reviewing the
+evidence believes that, as a rule, it deposits its young in the sleeping
+places of man and animals, whether such be a bed, a board, the floor, or
+the bare ground. In the case of babies, the maggots may be deposited on
+the scalp. The minute maggots bore their way painlessly into the skin.
+As many as forty parasites have been found in one individual and one
+author has reported finding more than three hundred in a spaniel puppy.
+Though their attacks are at times extremely painful, it is seldom that
+any serious results follow.
+
+
+THE SIPHONAPTERA OR FLEAS
+
+The SIPHONAPTERA, or fleas (fig. 89) are wingless insects, with highly
+chitinized and laterally compressed bodies. The mouth-parts are formed
+for piercing and sucking. Compound eyes are lacking but some species
+possess ocelli. The metamorphosis is complete.
+
+This group of parasites, concerning which little was known until
+recently, has assumed a very great importance since it was learned that
+fleas are the carriers of bubonic plague. Now over four hundred species
+are known. Of these, several species commonly attack man. The most
+common hominoxious species are _Pulex irritans_, _Xenopsylla cheopis_,
+_Ctenocephalus canis_, _Ctenocephalus felis_, _Ceratophyllus fasciatus_
+and _Dermatophilus penetrans_, but many others will feed readily on
+human blood if occasion arises.
+
+[Illustration: 89. Xenopsylla cheopis, male (x25). After Jordan and
+Rothschild.]
+
+We shall treat in this place of the general biology and habits of the
+hominoxious forms and reserve for the systematic section the discussion
+of the characteristics of the different genera.
+
+The most common fleas infesting houses in the Eastern United States are
+the cosmopolitan dog and cat fleas, _Ctenocephalus canis_ (fig. 90) and
+_C. felis_. Their life cycles will serve as typical. These two species
+have until recently been considered as one, under the name _Pulex
+serraticeps_. See figure 92.
+
+[Illustration: 90. Dog flea (x15). After Howard.]
+
+The eggs are oval, slightly translucent or pearly white, and measure
+about .5 mm. in their long diameter. They are deposited loosely in the
+hairs of the host and readily drop off as the animal moves around.
+Howard found that these eggs hatch in one to two days. The larvae are
+elongate, legless, white, worm-like creatures. They are exceedingly
+active, and avoid the light in every way possible. They cast their first
+skin in from three to seven days and their second in from three to four
+days. They commenced spinning in from seven to fourteen days after
+hatching and the imago appeared five days later. Thus in summer, at
+Washington, the entire life cycle may be completed in about two weeks.
+(cf. fig. 91, 92).
+
+Strickland's (1914) studies on the biology of the rat flea,
+_Ceratophyllus fasciatus_, have so important a general bearing that we
+shall cite them in considerable detail.
+
+[Illustration: 91. Larva of Xenopsylla cheopis. After Bacot and
+Ridewood.]
+
+He found, to begin with, that there is a marked inherent range in the
+rate of development. Thus, of a batch of seventy-three eggs, all laid in
+the same day and kept together under the same conditions, one hatched in
+ten days; four in eleven days; twenty-five in twelve days; thirty-one in
+thirteen days; ten in fourteen days; one in fifteen days; and one in
+sixteen days. Within these limits the duration of the egg period seems
+to depend mainly on the degree of humidity. The incubation period is
+never abnormally prolonged as in the case of lice, (Warburton) and
+varying conditions of temperature and humidity have practically no
+effect on the percentage of eggs which ultimately hatch.
+
+The same investigator found that the most favorable condition for the
+larva is a low temperature, combined with a high degree of humidity; and
+that the presence of rubbish in which the larva may bury itself is
+essential to its successful development. When larvae are placed in a
+bottle containing either wood-wool soiled by excrement, or with feathers
+or filter paper covered with dried blood they will thrive readily and
+pupate. They seem to have no choice between dried blood and powdered rat
+feces for food, and also feed readily on flea excrement. They possess
+the curious habit of always devouring their molted skins.
+
+[Illustration: 92. Head and pronotum of (_a_) dog flea; (_b_) of cat
+flea; (_c_) of hen flea. After Rothschild. (_d_) Nycteridiphilus
+(Ischnopsyllus) hexactenus. After Oudemans.]
+
+An important part of Strickland's experiments dealt with the question of
+duration of the pupal stage under the influence of temperature and with
+the longevity and habits of the adult. In October, he placed a batch of
+freshly formed cocoons in a small dish that was kept near a white rat in
+a deep glass jar in the laboratory. Two months later one small and
+feeble flea had emerged, but no more until February, four months after
+the beginning of the experiment. Eight cocoons were then dissected and
+seven more found to contain the imago fully formed but in a resting
+state. The remainder of the batch was then placed at 70^o F. for one
+night, near a white rat. The next day all the cocoons were empty and the
+fleas were found on the white rat.
+
+Thus, temperature greatly influences the duration of the pupal period,
+which in _Ceratophyllus fasciatus_ averages seventeen days. Moreover,
+when metamorphosis is complete a low temperature will cause the imago to
+remain within the cocoon.
+
+Sexually mature and ovipositing fleas, he fed at intervals and kept
+alive for two months, when the experiment was discontinued. In the
+presence of rubbish in which they could bury themselves, unfed rat fleas
+were kept alive for many months, whereas in the absence of any such
+substratum they rarely lived a month. In the former case, it was found
+that the length of life is influenced to some degree by the temperature
+and humidity. In an experiment carried out at 70^o F. and 45 per cent
+humidity, the fleas did not live for more than four months, while in an
+experiment at 60^o F. and 70 per cent humidity they lived for at least
+seventeen months. There was no indication that fleas kept under these
+conditions sucked moisture from surrounding objects, and those kept in
+bell jars, with an extract of flea-rubbish on filter paper, did not live
+any longer than those which were not so supplied.
+
+Curiously enough, although the rat is the normal host of _Ceratophyllus
+fasciatus_, it was found that when given the choice these fleas would
+feed upon man in preference to rats. However, none of the fleas laid
+eggs unless they fed on rat blood.
+
+The experiments of Strickland on copulation and oviposition in the rat
+flea showed that fleas do not copulate until they are sexually mature
+and that, at least in the case of _Ceratophyllus fasciatus_, the
+reproductive organs are imperfectly developed for some time (more than a
+week) after emerging from the pupa. When mature, copulation takes place
+soon after the fleas have fed on their true host--the rat--but not if
+they have fed on a facultative host only, such as man. Copulation is
+always followed by oviposition within a very short time.
+
+The effect of the rat's blood on the female with regard to egg-laying,
+Strickland concludes, is stimulating rather than nutritive, as fleas
+that were without food for many months were observed to lay eggs
+immediately after one feed. Similarly, the male requires the stimulus of
+a meal of rat's blood before it displays any copulatory activity.
+
+Mitzmain (1910) has described in detail the act of biting on man, as
+observed in the squirrel flea, _Ceratophyllus acutus_. "The flea when
+permitted to walk freely on the arm selects a suitable hairy space where
+it ceases abruptly in its locomotion, takes a firm hold with the tarsi,
+projects its proboscis, and prepares to puncture the skin. A puncture is
+drilled by the pricking epipharynx, the saw-tooth mandibles
+supplementing the movement by lacerating the cavity formed. The two
+organs of the rostrum work alternately, the middle piece boring, while
+the two lateral elements execute a sawing movement. The mandibles, owing
+to their basal attachments, are, as is expressed by the advisory
+committee on plague investigations in India (_Journal of Hygiene_, vol.
+6, No. 4, p. 499), 'capable of independent action, sliding up and down
+but maintaining their relative positions and preserving the lumen of the
+aspiratory channel.' The labium doubles back, the V-shaped groove of
+this organ guiding the mandibles on either side."
+
+"The action of the proboscis is executed with a forward movement of the
+head and a lateral and downward thrust of the entire body. As the
+mouth-parts are sharply inserted, the abdomen rises simultaneously. The
+hind and middle legs are elevated, resembling oars. The forelegs are
+doubled under the thorax, the tibia and tarsi resting firmly on the
+epidermis serve as a support for the body during the feeding. The
+maxillary palpi are retracted beneath the head and thorax. The labium
+continues to bend, at first acting as a sheath for the sawing mandibles,
+and as these are more deeply inserted, it bends beneath the head with
+the elasticity of a bow, forcing the mandibles into the wound until the
+maxillae are embedded in the skin of the victim. When the proboscis is
+fully inserted, the abdomen ceases for a time its lateral swinging."
+
+"The acute pain of biting is first felt when the mandibles have not
+quite penetrated and subsequently during each distinct movement of the
+abdomen. The swinging of the abdomen gradually ceases as it becomes
+filled with blood. The sting of the biting gradually becomes duller and
+less sensitive as feeding progresses. The movements of the elevated
+abdomen grow noticeably feebler as the downward thrusts of the springy
+bow-like labium becomes less frequent."
+
+"As the feeding process advances one can discern through the translucent
+walls of the abdomen a constant flow of blood, caudally from the
+pharynx, accompanied by a peristaltic movement. The end of the meal is
+signified in an abrupt manner. The flea shakes its entire body, and
+gradually withdraws its proboscis by lowering the abdomen and legs and
+violently twisting the head."
+
+"When starved for several days the feeding of the rat fleas is conducted
+in a rather vigorous manner. As soon as the proboscis is buried to the
+full length the abdomen is raised and there ensues a gradual lateral
+swaying motion, increasing the altitude of the raised end of the abdomen
+until it assumes the perpendicular. The flea is observed at this point
+to gain a better foothold by advancing the fore tarsi, and then,
+gradually doubling back the abdomen, it turns with extreme agility,
+nearly touching with its dorsal side the skin of the hand upon which it
+is feeding. Meanwhile, the hungry parasite feeds ravenously."
+
+"It is interesting to note the peculiar nervous action which the rodent
+fleas exhibit immediately when the feeding process is completed or when
+disturbed during the biting. Even while the rostrum is inserted to the
+fullest the parasite shakes its head spasmodically; in a twinkling the
+mouth is withdrawn and then the flea hops away."
+
+A habit of fleas which we shall see is of significance in considering
+their agency in the spread of bubonic plague, is that of ejecting blood
+from the anus as they feed.
+
+Fleas are famous for their jumping powers, and in control measures it is
+of importance to determine their ability along this line. It is often
+stated that they can jump about four inches, or, according to the Indian
+Plague Commission _Xenopsylla cheopis_ cannot hop farther than five
+inches. Mitzmain (1910) conducted some careful experiments in which he
+found that the human flea, _Pulex irritans_, was able to jump as far as
+thirteen inches on a horizontal plane. The mean average of five
+specimens permitted to jump at will was seven and three-tenths inches.
+The same species was observed to jump perpendicularly to a height of at
+least seven and three-fourths inches. Other species were not able to
+equal this record.
+
+The effect of the bite of fleas on man varies considerably according to
+the individual susceptibility. According to Patton and Cragg, this was
+borne out in a curious manner by the experiments of Chick and Martin.
+"In these, eight human hosts were tried; in seven, little or no
+irritation was produced, while in one quite severe inflammation was set
+up around each bite." Of two individuals, equally accustomed to the
+insects, going into an infested room, one may be literally tormented by
+them while the other will not notice them. Indeed it is not altogether
+a question of susceptibility, for fleas seem to have a special
+predilection for certain individuals. The typical itching wheals
+produced by the bites are sometimes followed, especially after
+scratching, by inflammatory papules.
+
+The itching can be relieved by the use of lotions of carbolic acid (2-3
+per cent), camphor, menthol lotion, or carbolated vaseline. If forced to
+sleep in an infested room, protection from attacks can be in a large
+measure gained by sprinkling pyrethrum, bubach, or California insect
+powder between the sheets. The use of camphor, menthol, or oil of
+eucalyptus, or oil of pennyroyal is also said to afford protection to a
+certain extent.
+
+In the Eastern United States the occurrence of fleas as household pests
+is usually due to infested cats and dogs which have the run of the
+house. We have seen that the eggs are not attached to the host but drop
+to the floor when they are laid. Verrill, cited by Osborn, states that
+on one occasion he was able to collect fully a teaspoonful of eggs from
+the dress of a lady in whose lap a half-grown kitten had been held for a
+short time. Patton and Cragg record seeing the inside of a hat in which
+a kitten had spent the night, so covered with flea eggs that it looked
+"as if it had been sprinkled with sugar from a sifter." It is no wonder
+that houses in which pets live become overrun with the fleas.
+
+One of the first control measures, then, consists in keeping such
+animals out of the house or in rigorously keeping them free from fleas.
+The latter can best be accomplished by the use of strong tar soap or
+Armour's "Flesope," which may be obtained from most druggists. The use
+of a three per cent solution of creolin, approximately four teaspoonfuls
+to a quart of warm water, has also been recommended. While this is
+satisfactory in the case of dogs, it is liable to sicken cats, who will
+lick their fur in an effort to dry themselves. Howard recommends
+thoroughly rubbing into the fur a quantity of pyrethrum powder. This
+partially stupifies the fleas which should be promptly swept up and
+burned.
+
+He also recommends providing a rug for the dog or cat to sleep on and
+giving this rug a frequent shaking and brushing, afterwards sweeping up
+and burning the dust thus removed.
+
+Since the larvae of fleas are very susceptible to exposure, the use of
+bare floors, with few rugs, instead of carpets or matting, is to be
+recommended. Thorough sweeping, so as to allow no accumulation of dust
+in cracks and crevices will prove efficient. If a house is once
+infested it may be necessary to thoroughly scrub the floors with hot
+soapsuds, or to spray them with gasoline. If the latter method is
+adopted, care must be taken to avoid the possibility of fire.
+
+To clear a house of fleas Skinner recommends the use of flake
+naphthalene. In a badly infested house he took one room at a time,
+scattering on the floor five pounds of flake naphthalene, and closed it
+for twenty-four hours. It proved to be a perfect and effectual remedy
+and very inexpensive, as the naphthalene could be swept up and
+transferred to other rooms. Dr. Skinner adds, "so far as I am concerned,
+the flea question is solved and if I have further trouble I know the
+remedy. I intend to keep the dog and cat."
+
+The late Professor Slingerland very effectively used hydrocyanic acid
+gas fumigation in exterminating fleas in houses. In one case, where
+failure was reported, he found on investigation that the house had
+become thoroughly reinfested from pet cats, which had been left
+untreated. Fumigation with sulphur is likewise efficient.
+
+The fact that adult fleas are usually to be found on the floor, when not
+on their hosts, was ingeniously taken advantage of by Professor S. H.
+Gage in ridding an animal room at Cornell University of the pests. He
+swathed the legs of a janitor with sticky fly-paper and had him walk
+back and forth in the room. Large numbers of the fleas were collected in
+this manner.
+
+In some parts of the southern United States hogs are commonly infested
+and in turn infest sheds, barns and even houses. Mr. H. E. Vick informs
+us that it is a common practice to turn sheep into barn-lots and sheds
+in the spring of the year to collect in their wool, the fleas which
+abound in these places after the hogs have been turned out.
+
+It is a common belief that adult fleas are attracted to fresh meat and
+that advantage of this can be taken in trapping them. Various workers,
+notably Mitzman (1910), have shown that there is no basis for such a
+belief.
+
+
+THE TRUE CHIGGERS--The chigoes, or true chiggers, are the most
+completely parasitic of any of the fleas. Of the dozen or more known
+species, one commonly attacks man. This is _Dermatophilus penetrans_,
+more commonly known as _Sarcopsylla penetrans_ or _Pulex penetrans_.
+
+This species occurs in Mexico, the West Indies, Central and South
+America. There are no authentic records of its occurrence in the United
+States although, as Baker has pointed out, there is no reason why it
+should not become established in Florida and Texas. It is usually
+believed that Brazil was its original home. Sometime about the middle of
+the nineteenth century it was introduced into West Africa and has spread
+across that continent.
+
+The males and the immature females of _Dermatophilus penetrans_ (fig.
+93) closely resemble those of other fleas. They are very active little
+brown insects about 1-1.2 mm. in size, which live in the dust of native
+huts and stables, and in dry, sandy soil. In such places they often
+occur in enormous numbers and become a veritable plague.
+
+[Illustration: 93. Dermatophilus penetrans. Much enlarged. After
+Karsten.]
+
+They attack not only man but various animals. According to Castellani
+and Chalmers, "Perhaps the most noted feature is the way in which it
+attacks pigs. On the Gold Coast it appeared to be largely kept in
+existence by these animals. It is very easily captured in the free state
+by taking a little pig with a pale abdomen, and placing it on its back
+on the ground on which infected pigs are living. After watching a few
+moments, a black speck will appear on the pig's abdomen, and quickly
+another and another. These black specks are jiggers which can easily be
+transferred to a test tube. On examination they will be found to be
+males and females in about equal numbers."
+
+Both the males and females suck blood. That which characterizes this
+species as distinguished from other fleas attacking man is that when the
+impregnated female attacks she burrows into the skin and there swells
+until in a few days she has the size and appearance of a small pea (fig.
+94). Where they are abundant, hundreds of the pests may attack a single
+individual (fig. 95). Here they lie with the apex of the abdomen
+blocking the opening. According to Fulleborn (1908) they do not
+penetrate beneath the epidermis. The eggs are not laid in the flesh of
+the victim, as is sometimes stated, but are expelled through this
+opening. The female then dies, withers and falls away or is expelled by
+ulceration. According to Brumpt, she first quits the skin and then,
+falling to the ground, deposits her eggs. The subsequent development in
+so far as known, is like that of other fleas.
+
+[Illustration: 94. Dermatophilus penetrans, gravid female. After
+Moniez.]
+
+[Illustration: 95. Chiggers in the sole of foot of man. Manson's
+Tropical Diseases. Permission of Cassell and Co.]
+
+The chigoe usually enters between the toes, the skin about the roots of
+the nails, or the soles of the feet, although it may attack other parts
+of the body. Mense records the occurrence in folds of the epidermis, as
+in the neighborhood of the anus. They give rise to irritation and unless
+promptly and aseptically removed there often occurs pus formation and
+the development of a more or less serious abscess. Gangrene and even
+tetanus may ensue.
+
+Treatment consists in the careful removal of the insect, an operation
+more easily accomplished a day or two after its entrance, than at first,
+when it is unswollen. The ulcerated point should then be treated with
+weak carbolic acid, or tincture of iodine, or dusted thoroughly with an
+antiseptic powder.
+
+[Illustration: 96. Echidnophaga gallinacea.]
+
+[Illustration: 97. Echidnophaga gallinacea infesting head of chicken.
+After Enderlein.]
+
+Castellani and Chalmers recommend as prophylactic measures, keeping the
+house clean and keeping pigs, poultry, and cattle away therefrom. "High
+boots should be used, and especial care should be taken not to go to a
+ground floor bathroom with bare feet. The feet, especially the toes, and
+under the nails, should be carefully examined every morning to see if
+any black dots can be discovered, when the jigger should be at once
+removed, and in this way suppuration will be prevented. It is
+advisable, also, to sprinkle the floors with carbolic lotion, Jeyes'
+fluid, or with pyrethrum powder, or with a strong infusion of native
+tobacco, as recommended by Law and Castellani."
+
+_Echidnophaga gallinacea_ (fig. 96) is a widely distributed Hectopsyllid
+attacking poultry (fig. 97). It occurs in the Southern and Southwestern
+United States and has been occasionally reported as attacking man,
+especially children. It is less highly specialized than _Dermatophilus
+penetrans_, and does not ordinarily cause serious trouble in man.
+
+
+
+
+CHAPTER IV
+
+ACCIDENTAL OR FACULTATIVE PARASITES
+
+
+In addition to the many species of Arthropods which are normally
+parasitic on man and animals, there is a considerable number of those
+which may be classed as _accidental_ or _facultative_ parasites.
+
+Accidental or facultative parasites are species which are normally
+free-living, but which are able to exist as parasites when accidentally
+introduced into the body of man or other animal. A wide range of forms
+is included under this grouping.
+
+
+ACARINA
+
+A considerable number of mites have been reported as accidental or even
+normal, endoparasites of man, but the authentic cases are comparatively
+few.
+
+In considering such reports it is well to keep in mind von Siebold's
+warning that in view of the universal distribution of mites one should
+be on his guard. In vessels in which animal and other organic fluids and
+moist substances gradually dry out, mites are very abundantly found. If
+such vessels are used without very careful preliminary cleaning, for the
+reception of evacuations of the sick, or for the reception of parts
+removed from the body, such things may be readily contaminated by mites,
+which have no other relation whatever to them.
+
+Nevertheless, there is no doubt but that certain mites, normally
+free-living, have occurred as accidental parasites of man. Of these the
+most commonly met with is _Tyroglyphus siro_, the cheese-mite.
+
+_Tyroglyphus siro_ is a small mite of a whitish color. The male measures
+about 500u long by 250u wide, the female slightly larger. They live in
+cheese of almost any kind, especially such as is a little decayed. "The
+individuals gather together in winter in groups or heaps in the hollows
+and chinks of the cheese and there remain motionless. As soon as the
+temperature rises a little, they gnaw away at the cheese and reduce it
+to a powder. The powder is composed of excrement having the appearance
+of little grayish microscopic balls; eggs, old and new, cracked and
+empty; larvae, nymphs, and perfect mites, cast skins and fragments of
+cheese, to which must be added numerous spores of microscopic
+fungi."--Murray.
+
+_Tyroglyphus siro_, and related species, have been found many times in
+human feces, under conditions which preclude the explanation that the
+contamination occurred outside of the body. They have been supposed to
+be the cause of dysentery, or diarrhoea, and it is probable that the
+_Acarus dysenteriae_ of Linnaeus, and Latreille, was this species.
+However, there is little evidence that the mites cause any noteworthy
+symptoms, even when taken into the body in large numbers.
+
+_Histiogaster spermaticus_ (fig. 152) is a Tyroglyphid mite which was
+reported by Trouessart (1902) as having been found in a cyst in the
+groin, adherent to the testis. When the cyst was punctured, it yielded
+about two ounces of opalescent fluid containing spermatozoa and numerous
+mites in all stages of development. The evidence indicated that a
+fecundated female mite had been introduced into the urethra by means of
+an unclean catheter. Though Trouessart reported the case as that of a
+Sarcoptid, Banks places the genus _Histiogaster_ with the Tyroglyphidae.
+He states that our species feeds on the oyster-shell bark louse,
+possibly only after the latter is dead, and that in England a species
+feeds within decaying reeds.
+
+_Nephrophages sanguinarius_ is a peculiarly-shaped, angular mite which
+was found by Miyake and Scriba (1893) for eight successive days in the
+urine of a Japanese suffering from fibrinuria. Males, .117 mm. long by
+.079 mm. wide, females .36 mm. by. 12 mm., and eggs were found both in
+the spontaneously emitted urine and in that drawn by means of a
+catheter. All the mites found were dead. The describers regarded this
+mite as a true endoparasite, but it is more probable that it should be
+classed as an accidental parasite.
+
+
+MYRIAPODA
+
+There are on record a number of cases of myriapods occurring as
+accidental parasites of man. The subject has been treated in detail by
+Blanchard (1898 and 1902), who discussed forty cases. Since then at
+least eight additions have been made to the list.
+
+Neveau-Lamaire (1908) lists thirteen species implicated, representing
+eight different genera. Of the _Chilognatha_ there are three, _Julus
+terrestris_, _J. londinensis_ and _Polydesmus complanatus_. The
+remainder are _Chilopoda_, namely, _Lithobius forficatus_, _L.
+malenops_, _Geophilus carpophagus_, _G. electricus_, _G. similis_, _G.
+cephalicus_, _Scutigera coleoptrata_, _Himantarium gervaisi_,
+_Chaetechelyne vesuviana_ and _Stigmatogaster subterraneus_.
+
+The majority of the cases relate to infestation of the nasal fossae, or
+the frontal sinus, but intestinal infestation also occurs and there is
+one recorded case of the presence of a species in _Julus_ (fig. 13) in
+the auditory canal of a child.
+
+In the nose, the myriapods have been known to live for months and
+according to some records, even for years. The symptoms caused by their
+presence are inflammation, with or without increased flow of mucus,
+itching, more or less intense headache, and at times general symptoms
+such as vertigo, delirium, convulsions, and the like. These symptoms
+disappear suddenly when the parasites are expelled.
+
+In the intestine of man, myriapods give rise to obscure symptoms
+suggestive of infestation by parasitic worms. In a case reported by
+Verdun and Bruyant (1912), a child twenty months of age had been
+affected for fifteen days by digestive disturbances characterized by
+loss of appetite, nausea and vomiting. The latter had been particularly
+pronounced for three days, when there was discovered in the midst of the
+material expelled a living myriapod of the species _Chaetechelyne
+vesuviana_. Anthelminthics had been administered without result. In some
+of the other cases, the administration of such drugs had resulted in the
+expulsion of the parasite through the anus.
+
+One of the extreme cases on record is that reported by Shipley (1914).
+Specimens of _Geophilus gorizensis_ (= _G. subterraneus_) "were vomited
+and passed by a woman of 68 years of age. Some of the centipedes emerged
+through the patient's nose, and it must be mentioned that she was also
+suffering from a round worm. One of her doctors was of the opinion that
+the centipedes were certainly breeding inside the lady's intestines, and
+as many as seven or eight, sometimes more, were daily leaving the
+alimentary canal."
+
+"According to her attendant's statements those centipedes had left the
+body in some hundreds during a period of twelve or eighteen months.
+Their presence produced vomiting and some haematemesis, and treatment
+with thymol, male-fern and turpentine had no effect in removing the
+creatures."
+
+The clinical details, as supplied by Dr. Theodore Thompson were as
+follows:
+
+"Examined by me July, 1912, her tongue was dry and glazed. There was
+bleeding taking place from the nose and I saw a living centipede she had
+just extracted from her nostril. Her heart, lungs and abdomen appeared
+normal. She was not very wasted, and did not think she had lost much
+flesh, nor was there any marked degree of anemia."
+
+Shipley gives the following reasons for believing it impossible that
+these centipedes could have multiplied in the patient's intestine. "The
+breeding habits of the genus _Geophilus_ are peculiar, and ill adapted
+for reproducing in such a habitat. The male builds a small web or nest,
+in which he places his sperm, and the female fertilizes herself from
+this nest or web, and when the eggs are fertilized they are again laid
+in a nest or web in which they incubate and in two or three weeks hatch
+out. The young _Geophilus_ differ but very little from the adult, except
+in size. It is just possible, but improbable, that a clutch of eggs had
+been swallowed by the host when eating some vegetables or fruit, but
+against this is the fact that the _Geophilus_ does not lay its eggs upon
+vegetables or fruit, but upon dry wood or earth. The egg-shell is very
+tough and if the eggs had been swallowed the egg-shells could certainly
+have been detected if the dejecta were examined. The specimens of the
+centipede showed very little signs of being digested, and it is almost
+impossible to reconcile the story of the patient with what one knows of
+the habits of the centipedes."
+
+In none of the observed cases have there been any clear indications as
+to the manner of infestation. It is possible that the myriapods have
+been taken up in uncooked fruit or vegetables.
+
+
+LEPIDOPTEROUS LARVAE
+
+SCHOLECIASIS--Hope (1837) brought together six records of infestation of
+man by lepidopterous larvae and proposed to apply the name scholeciasis
+to this type of parasitism. The clearest case was that of a young boy
+who had repeatedly eaten raw cabbage and who vomited larvae of the
+cabbage butterfly, _Pieris brassicae_. Such cases are extremely rare, and
+there are few reliable data relative to the subject. In this connection
+it may be noted that Spuler (1906) has described a moth whose larvae live
+as ectoparasites of the sloth.
+
+
+COLEOPTERA
+
+CANTHARIASIS--By this term Hope designated instances of accidental
+parasitism by the larvae or adults of beetles. Reports of such cases
+are usually scouted by parasitologists but there seems no good basis for
+wholly rejecting them. Cobbold refers to a half dozen cases of
+accidental parasitism by the larvae of _Blaps mortisaga_. In one of
+these cases upwards of 1200 larvae and several perfect insects were
+said to have been passed _per annum_. French (1905) reports the case of
+a man who for a considerable period voided adult living beetles of the
+species _Nitidula bipustulata_. Most of the other cases on record relate
+to the larvae of _Dermestidae_ (larder beetles _et al._) or
+_Tenebrionidae_ (meal infesting species). Infestation probably occurs
+through eating raw or imperfectly cooked foods containing eggs or minute
+larvae of these insects.
+
+[Illustration: 98. Larva of Piophila casei. Caudal aspect of larva.
+Posterior stigmata.]
+
+Brumpt cites a curious case of accidental parasitism by a coleopterous
+larva belonging to the genus _Necrobia_. This larva was extracted from a
+small tumor, several millimeters long, on the surface of the conjunctiva
+of the eye. The larvae of this genus ordinarily live in decomposing flesh
+and cadavers.
+
+
+DIPTEROUS LARVAE
+
+[Illustration: 99. Piophila casei. After Graham-Smith.]
+
+MYASIS--By this term (spelled also myiasis, and myiosis), is meant
+parasitism by dipterous larvae. Such parasitism may be normal, as in the
+cases already described under the heading parasitic Diptera, or it may
+be facultative, due to free-living larvae being accidentally introduced
+into wounds or the body-cavities of man. Of this latter type, there is a
+multitude of cases on record, relating to comparatively few species. The
+literature of the subject, like that relating to facultative parasitism
+in general, is unsatisfactory, for most of the determinations of species
+have been very loose. Indeed, so little has been known regarding the
+characteristics of the larvae concerned that in many instances they could
+not be exactly determined. Fortunately, several workers have undertaken
+comparative studies along this line. The most comprehensive publication
+is that of Banks (1912), entitled "The structure of certain dipterous
+larvae, with particular reference to those in human food."
+
+Without attempting an exhaustive list, we shall discuss here the more
+important species of Diptera whose larvae are known to cause myasis,
+either external or internal. The following key will serve to determine
+those most likely to be encountered. The writers would be glad to
+examine specimens not readily identifiable, if accompanied by exact data
+relative to occurrence.
+
+_a._ Body more or less flattened, depressed; broadest in the middle,
+    each segment with dorsal, lateral, and ventral fleshy processes, of
+    which the laterals, at least, are more or less spiniferous (fig.
+    101). _Fannia_ (= _Homalomyia_).
+
+  In _F. canicularis_ the dorsal processes are nearly as long as the
+      laterals; in _F. scalaris_ the dorsal processes are short spinose
+      tubercles.
+
+_aa._ Body cylindrical, or slender conical tapering toward the head;
+    without fleshy lateral processes (fig. 105).
+
+_b._ With the posterior stigmata at the end of shorter or longer
+    tubercles, or if not placed upon tubercles, then not in pit; usually
+    without a "marginal button" and without a chitinous ring surrounding
+    the three slits; the slits narrowly or broadly oval, not bent (fig.
+    171 i). _Acalyptrate muscidae_ and some species of
+    _Anthomyiidae_. To this group belong the cheese skipper (_Piophila
+    casei_, figs. 98, 99), the pomace-fly (_Drosophila ampelophila_),
+    the apple maggot (_Rhagoletis pomonella_), the cherry fruit fly
+    (_Rhagoletis cingulata_), the small dung fly (_Sepsis violacea_,
+    fig. 170), the beet leaf-miner (_Pegomyia vicina_, fig. 171 i), the
+    cabbage, bean and onion maggots (_Phorbia_ spp.) et. al.
+
+_bb._ Posterior stigmata of various forms, if the slits are narrowly
+    oval (fig. 171) then they are surrounded by a chitin ring which may
+    be open ventro-mesally.
+
+_c._ Integument leathery and usually strongly spinulose; larvae
+    hypodermatic or endoparasitic. Bot flies (fig. 171, f, g,
+    k).--_Oestridae_
+
+_cc._ Integument not leathery and (except in _Protocalliphora_) spinulae
+    restricted to transverse patches near the incisures of the segments.
+
+_d._ The stigmal plates in a pit; the lip-like margin of the pit with a
+    number of fleshy tubercles; chitin ring of the stigma not complete;
+    open ventro-mesally, button absent (fig. 171 e). Flesh
+    flies.--_Sarcophaga_
+
+_dd._ Stigmata not in a pit.
+
+_e._ The chitin ring open ventra-mesally; button absent (fig. 171 c).
+    Screw-worm fly. _Chrysomyia_
+
+_ee._ The chitin ring closed.
+
+_f._ Slits of the posterior stigmata straight; marginal "button" present
+    (fig. 171 b); two distinct mouth hooks, fleshy tubercles around the
+    anal area. _Phormia_ (fig. 171 f), _Lucilia_ and _Calliphora_ (fig.
+    172, a, b), _Protocalliphora_ (fig. 171, j), _Cynomyia_ (fig. 171,
+    a). Blow flies, bluebottle flies. _Calliphorinae_
+
+_ff._ Slits of the posterior stigmata sinuous or bent. Subfamily
+    Muscinae.
+
+_g._ Slits of the posterior stigmata bent; usually two mouth hooks.
+    _Muscina stabulans_ (fig. 171, l), _Muscina similis_, _Myiospila
+    meditabunda_ (fig. 172, i), and some of the higher _Anthomyiidae_.
+
+_gg._ Slits of the posterior stigmata sinuous; mouth hooks usually
+    consolidated into one. The house-fly (_Musca domestica_ fig. 171,
+    d), the stable fly (_Stomoxys calcitrans_), the horn fly (_Lyperosia
+    irritans_), _Pyrellia_, _Pseudopyrellia_, _Morellia_, _Mesembrina_.
+    _Polietes_, et. al. (fig. 172 in part).
+
+_Eristalis_--The larvae of _Eristalis_ are the so-called rat-tailed
+maggots, which develop in foul water. In a few instances these larvae
+have been known to pass through the human alimentary canal uninjured.
+Hall and Muir (1913) report the case of a boy five years of age, who had
+been ailing for ten weeks and who was under treatment for indigestion
+and chronic constipation. For some time he had vomited everything he
+ate. On administration of a vermifuge he voided one of the rat-tailed
+maggots of _Eristalis_. He admitted having drunk water from a ditch full
+of all manner of rotting matter. It was doubtless through this that he
+became infested. It is worth noting that the above described symptoms
+may have been due to other organisms or substances in the filthy water.
+
+_Piophila casei_, the cheese-fly (fig. 99), deposits its eggs not only
+in old cheeses, but on ham, bacon, and other fats. The larvae (fig. 98)
+are the well-known cheese skippers, which sometimes occur in great
+abundance on certain kinds of cheese. Indeed, some people have a
+comfortable theory that such infested cheese is especially good. Such
+being the case, it is small wonder that this species has been repeatedly
+reported as causing intestinal myasis. Thebault (1901) describes the
+case of a girl who, shortly after consuming a large piece of badly
+infested cheese, became ill and experienced severe pains in the region
+of the navel. Later these extended through the entire alimentary canal,
+the excrement was mixed with blood and she suffered from vertigo and
+severe headaches. During the four following days the girl felt no
+change, although the excretion of the blood gradually diminished and
+stopped. On the fourth day she voided two half-digested larvae and,
+later, seven or eight, of which two were alive and moving.
+
+That these symptoms may be directly attributed to the larvae, or
+"skippers," has been abundantly shown by experimental evidence.
+Portschinsky cites the case of a dog fed on cheese containing the larvae.
+The animal suffered much pain and its excrement contained blood. On
+_post mortem_ it was found that the small intestine throughout almost
+its entire length was marked by bloody bruises. The papillae on these
+places were destroyed, although the walls were not entirely perforated.
+In the appendix were found two or three dead larvae. Alessandri (1910)
+has likewise shown that the larvae cause intestinal lesions.
+
+According to Graham-Smith, Austen (1912) has recorded a case of myasis
+of the nose, attended with a profuse watery discharge of several weeks
+duration and pain, due to the larvae of _Piophila casei_.
+
+
+ANTHYOMYIIDAE--The characteristic larvae of two species of _Fannia_ (=
+_Homalomyia_ or _Anthomyia_, in part) (fig. 101) are the most commonly
+reported of dipterous larvae causing intestinal myasis. Hewitt (1912) has
+presented a valuable study of the bionomics and of the larvae of these
+flies, a type of what is needed for all the species concerned in myasis.
+We have seen two cases of their having been passed in stools, without
+having caused any special symptoms. In other instances their presence in
+the alimentary canal has given rise to symptoms vaguely described as
+those of tapeworm infestation, or helminthiasis. More specifically, they
+have been described as causing vertigo, severe headache, nausea and
+vomiting, severe abdominal pains, and in some instances, bloody
+diarrhoea.
+
+[Illustration: 100. Fannia canicularis (x4). After Graham-Smith.]
+
+One of the most striking cases is that reported by Blankmeyer (1914), of
+a woman whose illness began fourteen years previously with nausea and
+vomiting. After several months of illness she began passing larvae and
+was compelled to resort to enemas. Three years previous to the report,
+she noticed frequent shooting pains in the rectal region and at times
+abdominal tenderness was marked. There was much mucus in the stools and
+she "experienced the sensation of larvae crawling in the intestine."
+Occipital headaches were marked, with remissions, and constipation
+became chronic. The appetite was variable, there was a bad taste in the
+mouth, tongue furred and ridged, and red at the edges. Her complexion
+was sallow, and general nervousness was marked. As treatment, there were
+given doses of magnesium sulphate before breakfast and at 4 P. M., with
+five grain doses of salol four times a day. The customary parasiticides
+yielded no marked benefit. At the time of the report the patient passed
+from four to fifty larvae per day, and was showing some signs of
+improvement. The nausea had disappeared, her nervousness was less
+evident, and there was a slight gain in weight.
+
+The case was complicated by various other disorders, but the symptoms
+given above seem to be in large part attributable to the myasis. There
+is nothing in the case to justify the assumption that larvae were
+continuously present, for years. It seems more reasonable to suppose
+that something in the habits of the patient favored repeated
+infestation. Nevertheless, a study of the various cases of intestinal
+myasis caused by these and other species of dipterous larvae seems to
+indicate that the normal life cycle may be considerably prolonged under
+the unusual conditions.
+
+The best authenticated cases of myasis of the urinary passage have been
+due to larvae of _Fannia_. Chevril (1909) collected and described twenty
+cases, of which seven seemed beyond doubt. One of these was that of a
+woman of fifty-five who suffered from albuminuria, and urinated with
+much difficulty, and finally passed thirty to forty larvae of _Fannia
+canicularis_.
+
+It is probable that infestation usually occurs through eating partially
+decayed fruit or vegetables on which the flies have deposited their
+eggs. Wellman points out that the flies may deposit their eggs in or
+about the anus of persons using outside privies and Hewitt believes that
+this latter method of infection is probably the common one in the case
+of infants belonging to careless mothers. "Such infants are sometimes
+left about in an exposed and not very clean condition, in consequence of
+which flies are readily attracted to them and deposit their eggs."
+
+[Illustration: 101. Larva of Fannia scalaris.]
+
+
+MUSCINAE--The larvae of the common house-fly, _Musca domestica_, are
+occasionally recorded as having been passed with the feces or vomit of
+man. While such cases may occur, it is probable that in most instances
+similar appearing larvae of other insects have been mistakenly
+identified.
+
+_Muscina stabulans_ is regarded by Portschinsky (1913) as responsible
+for many of the cases of intestinal myasis attributed to other species.
+He records the case of a peasant who suffered from pains in the lower
+part of the breast and intestines, and whose stools were mixed with
+blood. From November until March he had felt particularly ill, being
+troubled with nausea and vomiting in addition to the pain in his
+intestines. In March, his physician prescribed injections of a
+concentrated solution of tannin, which resulted in the expulsion of
+fifty living larvae of _Muscina stabulans_. Thereafter the patient felt
+much better, although he suffered from intestinal catarrh in a less
+severe form.
+
+[Illustration: 102 Muscina stabulans (x4). After Graham-Smith.]
+
+
+CALLIPHORINAE--Closely related to the Sarcophagidae are the
+_Calliphorinae_, to which group belong many of the so-called "blue
+bottle" flies. Their larvae feed upon dead animals, and upon fresh and
+cooked meat. Those of _Protocalliphora_, already mentioned, are
+ectoparasitic on living nestling birds. Larva of _Lucilia_, we have
+taken from tumors on living turtles. To this sub-family belongs also
+_Auchmeromyia luteola_, the Congo floor maggot. Some of these, and at
+least the last mentioned, are confirmed, rather than faculative
+parasites. Various species of Calliphorinae are occasionally met with as
+facultative parasites of man.
+
+[Illustration: 103. Lucilia caesar, (x3). After Howard.]
+
+_Chrysomyia macellaria_, the screw worm fly (fig. 107), is the fly which
+is responsible for the most serious cases of human myasis in the United
+States. It is widely distributed in the United States but is especially
+abundant in the south. While the larvae breed in decaying matter in
+general, they so commonly breed in the living flesh of animals that they
+merit rank as true parasites. The females are attracted to open wounds
+of all kinds on cattle and other animals and quickly deposit large
+numbers of eggs. Animals which have been recently castrated, dehorned,
+or branded, injured by barbed wire, or even by the attacks of ticks are
+promptly attacked in the regions where the fly abounds. Even the navel
+of young calves or discharges from the vulva of cows may attract the
+insect.
+
+[Illustration: 104. Calliphora erythrocephala, (x6). After
+Graham-Smith.]
+
+Not infrequently the fly attacks man, being attracted by an offensive
+breath, a chronic catarrh, or a purulent discharge from the ears. Most
+common are the cases where the eggs are deposited in the nostrils. The
+larvae, which are hatched in a day or two, are provided with strong
+spines and proceed to bore into the tissues of the nose, even down into
+or through the bone, into the frontal sinus, the pharynx, larynx, and
+neighboring parts.
+
+Osborn (1896) quotes a number of detailed accounts of the attacks of the
+_Chrysomyia_ on man. A vivid picture of the symptomology of rhinal
+myasis caused by the larvae of this fly is given by Castellani and
+Chalmers: "Some couple of days after a person suffering from a chronic
+catarrh, foul breath, or ozaena, has slept in the open or has been
+attacked by a fly when riding or driving,--_i.e._, when the hands are
+engaged--signs of severe catarrh appear, accompanied with inordinate
+sneezing and severe pain over the root of the nose or the frontal bone.
+Quickly the nose becomes swollen, and later the face also may swell,
+while examination of the nose may show the presence of the larvae. Left
+untreated, the patient rapidly becomes worse, and pus and blood are
+discharged from the nose, from which an offensive odor issues. Cough
+appears as well as fever, and often some delirium. If the patient lives
+long enough, the septum of the nose may fall in, the soft and hard
+palates may be pierced, the wall of the pharynx may be destroyed. By
+this time, however, the course of the disease will have become quite
+evident by the larvae dropping out of the nose, and if the patient
+continues to live all the larvae may come away naturally."
+
+For treatment of rhinal myasis these writers recommend douching the nose
+with chloroform water or a solution of chloroform in sweet milk (10-20
+per cent), followed by douches of mild antiseptics. Surgical treatment
+may be necessary.
+
+[Illustration: 105. Larva of a flesh fly (Sarcophaga). Caudal aspect.
+Anterior stigmata. Pharyngeal skeleton.]
+
+
+SARCOPHAGIDAE--The larvae (fig. 105) of flies of this family usually
+feed upon meats, but have been found in cheese, oleomargerine, pickled
+herring, dead and living insects, cow dung and human feces. Certain
+species are parasitic in insects. Higgins (1890) reported an instance of
+"hundreds" of larvae of _Sarcophaga_ being vomited by a child eighteen
+months of age. There was no doubt as to their origin for they were
+voided while the physician was in the room. There are many other reports
+of their occurrence in the alimentary canal. We have recorded elsewhere
+(Riley, 1906) a case in which some ten or twelve larvae of
+_Sarcophaga_ were found feeding on the diseased tissues of a malignant
+tumor. The tumor, a melanotic sarcoma, was about the size of a small
+walnut, and located in the small of the back of an elderly lady.
+Although they had irritated and caused a slight haemorrhage, neither the
+patient nor others of the family knew of their presence. Any discomfort
+which they had caused had been attributed to the sarcomatous growth. The
+infestation occurred in mid-summer. It is probable that the adult was
+attracted by the odor of the discharges and deposited the living maggots
+upon the diseased tissues.
+
+[Illustration: 106. A flesh fly (Sarcophaga), (x4). After Graham-Smith.]
+
+According to Kuchenmeister, _Sarcophaga carnaria_ (fig. 106), attracted
+by the odor, deposits its eggs and larvae in the vagina of girls and
+women when they lie naked in hot summer days upon dirty clothes, or when
+they have a discharge from the vagina. In malignant inflammations of the
+eyes the larvae even nestle under the eyelids and in Egypt, for example,
+produce a very serious addition to the effects of small-pox upon the
+cornea, as according to Pruner, in such cases perforation of the cornea
+usually takes place.
+
+[Illustration: 107. Chrysomyia macellaria, (x3).]
+
+_Wohlfartia magnifica_ is another Sarcophagid which commonly infests man
+in the regions where it is abundant. It is found in all Europe but is
+especially common in Russia, where Portschinsky has devoted much
+attention to its ravages. It deposits living larvae in wounds, the nasal
+fossae, the ears and the eyes, causing injuries even more revolting than
+those described for _Chrysomyia_.
+
+
+
+
+CHAPTER V
+
+ARTHROPODS AS SIMPLE CARRIERS OF DISEASE
+
+
+The fact that certain arthropods are poisonous, or may affect the health
+of man as direct parasites has always received attention in the medical
+literature. We come now to the more modern aspect of our subject,--the
+consideration of insects and other arthropods as transmitters and
+disseminators of disease.
+
+The simplest way in which arthropods may function in this capacity is as
+_simple carriers_ of pathogenic organisms. It is conceivable that any
+insect which has access to, and comes in contact with such organisms and
+then passes to the food, or drink, or to the body of man, may in a
+wholly accidental and incidental manner convey infection. That this
+occurs is abundantly proved by the work of recent years. We shall
+consider as typical the case against the house-fly, which has attracted
+so much attention, both popular and scientific. The excellent general
+treatises of Hewitt (1910), Howard (1911), and Graham-Smith (1913), and
+the flood of bulletins and popular literature render it unnecessary to
+consider the topic in any great detail.
+
+
+THE HOUSE-FLY AS A CARRIER OF DISEASE
+
+Up to the past decade the house-fly has usually been regarded as a mere
+pest. Repeatedly, however, it had been suggested that it might
+disseminate disease. We have seen that as far back as the sixteenth
+century, Mercurialis suggested that it was the agent in the spread of
+bubonic plague, and in 1658, Kircher reiterated this view. In 1871,
+Leidy expressed the opinion that flies were probably a means of
+communicating contagious diseases to a greater degree than was generally
+suspected. From what he had observed regarding gangrene in hospitals, he
+thought flies should be carefully excluded from wounds. In the same
+year, the editor of the _London Lancet_, referring to the belief that
+they play a useful role in purifying the air said, "Far from looking
+upon them as dipterous angels dancing attendance on Hygeia, regard them
+rather in the light of winged sponges spreading hither and thither to
+carry out the foul behests of Contagion."
+
+These suggestions attracted little attention from medical men, for it is
+only within very recent years that the charges have been supported by
+direct evidence. Before considering this evidence, it is necessary that
+we define what is meant by "house-fly" and that we then consider the
+life-history of the insect.
+
+There are many flies which are occasionally to be found in houses, but
+according to various counts, from 95 per cent to 99 per cent of these in
+warm weather in the Eastern United States belong to the one species
+_Musca domestica_ (fig. 108). This is the dominant house-fly the world
+over and is the one which merits the name. It has been well
+characterized by Schiner (1864), whose description has been freely
+translated by Hewitt, as follows:
+
+"Frons of male occupying a fourth part of the breadth of the head.
+Frontal stripe of female narrow in front, so broad behind that it
+entirely fills up the width of the frons. The dorsal region of the
+thorax dusty grey in color with four equally broad longitudinal stripes.
+Scutellum gray with black sides. The light regions of the abdomen
+yellowish, transparent, the darkest parts at least at the base of the
+ventral side yellow. The last segment and a dorsal line blackish brown.
+Seen from behind and against the light, the whole abdomen shimmering
+yellow, and only on each side of the dorsal line on each segment a dull
+transverse band. The lower part of the face silky yellow, shot with
+blackish brown. Median stripe velvety black. Antennae brown. Palpi black.
+Legs blackish brown. Wings tinged with pale gray with yellowish base.
+The female has a broad velvety back, often reddishly shimmering frontal
+stripe, which is not broader at the anterior end than at the bases of
+the antennae, but become so very much broader above that the light
+dustiness of the sides is entirely obliterated. The abdomen gradually
+becoming darker. The shimmering areas on the separate segments generally
+brownish. All the other parts are the same as in the male."
+
+The other species of flies found in houses in the Eastern United States
+which are frequently mistaken for the house or typhoid fly may readily
+be distinguished by the characters of the following key:
+
+_a._ Apical cell (R_5) of the wide wing open, i.e., the bounding veins
+    parallel or divergent (fig. 100). Their larvae are flattened, the
+    intermediate body segments each fringed with fleshy, more or less
+    spinose, processes. _Fannia_
+
+  b. Male with the sides of the second and third abdominal segments
+      translucent yellowish. The larva with three pairs of nearly equal
+      spiniferous appendages on each segment, arranged in a
+      longitudinal series and in addition two pairs of series of smaller
+      processes (fig. 100) _F. canicularis_
+
+  bb. Male with blackish abdomen, middle tibia with a tubercle beyond
+      the middle. The larva with spiniferous appendages of which the
+      dorsal and ventral series are short, the lateral series long and
+      feathered (fig. 101) _F. scalaris_
+
+aa. Apical cell (R) of the wing more or less narrowed in the margin; i.
+    e., the bounding veins more or less converging (fig. 108).
+
+  b. The mouth-parts produced and pointed, fitted for piercing.
+
+    c. Palpi much shorter than the proboscis; a brownish gray fly, its
+        thorax with three rather broad whitish stripes; on each border
+        of the middle stripe and on the mesal borders of the lateral
+        stripes is a blackish brown line. Abdomen yellowish brown; on
+        the second, third and fourth segments are three brown spots
+        which may be faint or even absent. The larvae live in dung. The
+        stable-fly (fig. 110) _Stomoxys calcitrans_
+
+    cc. Palpi nearly as long as the proboscis. Smaller species than the
+        house-fly. The horn-fly (fig. 167) _Haematobia irritans_
+
+  bb. Mouth-parts blunt, fitted for lapping.
+
+    c. Thorax, particularly on the sides and near the base of the wings
+        with soft golden yellow hairs among the bristles. This fly is
+        often found in the house in very early spring or even in the
+        winter. The cluster-fly, _Pollenia rudis_
+
+    cc. Thorax without golden yellow hairs among the bristles.
+
+      d. The last segment of the vein M with an abrupt angle. (fig.
+          108). The larvae live in manure, etc. House-fly, _Musca
+          domestica_
+
+      dd. The last segment of vein M with a broad, gentle curve (fig.
+          102).
+
+        e. Eyes microscopically hairy; each abdominal segment with two
+            spots. Larvae in dung. _Myiospila meditabunda_
+
+        ee. Eyes bare; abdomen gray and brown marbled. _Muscina_
+
+          f. With black legs and palpi. _M. assimilis_
+
+          ff. With legs more or less yellowish; palpi yellow. Larvae in
+              decaying vegetable substances, dung, etc. _M. stabulans_
+
+It is almost universally believed that the adults of _Musca domestica_
+hibernate, remaining dormant throughout the winter in attics, around
+chimneys, and in sheltered but cold situations. This belief has been
+challenged by Skinner (1913), who maintains that all the adult flies die
+off during the fall and early winter and that the species is carried
+over in the pupal stage, and in no other way. The cluster-fly, _Pollenia
+rudis_, undoubtedly does hibernate in attics and similar situations and
+is often mistaken for the house-fly. In so far as concerns _Musca
+domestica_, the important question as to hibernation in the adult stage
+is an open one. Many observations by one of the writers (Johannsen) tend
+to confirm Dr. Skinner's conclusion, in so far as it applies to
+conditions in the latitude of New York State. Opposed, is the fact that
+various experimenters, notably Hewitt (1910) and Jepson (1909) wholly
+failed to carry pupae through the winter.
+
+[Illustration: 108. The house or typhoid fly (Musca domestica (x4)).
+After Howard.]
+
+The house-fly breeds by preference in horse manure. Indeed, Dr. Howard,
+whose extensive studies of the species especially qualify him for
+expressing an opinion on the subject, has estimated that under ordinary
+city and town conditions, more than ninety per cent of the flies present
+in houses have come from horse stables or their vicinity. They are not
+limited to such localities, by any means, for it has been found that
+they would develop in almost any fermenting organic substance. Thus,
+they have been bred from pig, chicken, and cow manure, dirty waste
+paper, decaying vegetation, decaying meat, slaughter-house refuse,
+sawdust-sweepings, and many other sources. A fact which makes them
+especially dangerous as disease-carriers is that they breed readily in
+human excrement.
+
+The eggs are pure white, elongate ovoid, somewhat broader at the
+anterior end. They measure about one millimeter (1-25 inch) in length.
+They are deposited in small, irregular clusters, one hundred and twenty
+to one hundred and fifty from a single fly. A female may deposit as many
+as four batches in her life time. The eggs hatch in from eight to
+twenty-four hours.
+
+The newly hatched larva, or maggot (fig. 108), measures about two
+millimeters (1-12 inch) in length. It is pointed at the head end and
+blunt at the opposite end, where the spiracular openings are borne. It
+grows rapidly, molts three times and reaches maturity in from six to
+seven days, under favorable conditions.
+
+The pupal stage, like that of related flies, is passed in the old larval
+skin which, instead of being molted, becomes contracted and heavily
+chitinized, forming the so-called _puparium_ (fig. 108). The pupal stage
+may be completed in from three to six days.
+
+Thus during the warm summer months a generation of flies may be produced
+in ten to twelve days. Hewitt at Manchester, England, found the minimum
+to be eight days but states that larvae bred in the open air in horse
+manure which had an average daily temperature of 22.5^o C., occupied
+fourteen to twenty days in their development, according to the air
+temperature.
+
+After emergence, a period of time must elapse before the fly is capable
+of depositing eggs. This period has been tuned the _preoviposition_
+period. Unfortunately we have few exact data regarding this period.
+Hewitt found that the flies became sexually mature in ten to fourteen
+days after their emergence from the pupal state and four days after
+copulation they began to deposit their eggs; in other words the
+preoviposition stage was fourteen days or longer. Griffith (1908) found
+this period to be ten days. Dr. Howard believes that the time "must
+surely be shorter, and perhaps much shorter, under midsummer conditions,
+and in the freedom of the open air." He emphasizes that the point is of
+great practical importance, since it is during this period that the
+trapping and other methods of destroying the adult flies, will prove
+most useful.
+
+Howard estimates that there may be nine generations of flies a year
+under outdoor conditions in places comparable in climate to Washington.
+The number may be considerably increased in warmer climates.
+
+The rate at which flies may increase under favorable conditions is
+astounding. Various writers have given estimates of the numbers of flies
+which may develop as the progeny of a single individual, providing all
+the eggs and all the individual flies survived. Thus, Howard estimates
+that from a single female, depositing one hundred and twenty eggs on
+April 15th, there may be by September 10th, 5,598,720,000,000 adults.
+Fortunately, living forms do not produce in any such mathematical manner
+and the chief value of the figures is to illustrate the enormous
+struggle for existence which is constantly taking place in nature.
+
+Flies may travel for a considerable distance to reach food and shelter,
+though normally they pass to dwellings and other sources of food supply
+in the immediate neighborhood of their breeding places. Copeman, Howlett
+and Merriman (1911) marked flies by shaking them in a bag containing
+colored chalk. Such flies were repeatedly recovered at distances of
+eight to one thousand yards and even at a distance of seventeen hundred
+yards, nearly a mile.
+
+Hindle and Merriman (1914) continued these experiments on a large scale
+at Cambridge, England. They "do not think it likely that, as a rule,
+flies travel more than a quarter of a mile in thickly-housed areas." In
+one case a single fly was recovered at a distance of 770 yards but a
+part of this distance was across open fen-land. The surprising fact was
+brought out that flies tend to travel either _against_ or across the
+wind. The actual direction followed may be determined either directly by
+the action of the wind (positive anemotropism), or indirectly owing to
+the flies being attracted by any odor that it may convey from a source
+of food. They conclude that it is likely that the chief conditions
+favoring the disposal of flies are fine weather and a warm temperature.
+The nature of the locality is another considerable factor. Hodge (1913)
+has shown that when aided by the wind they may fly to much greater
+distances over the water. He reports that at Cleveland, Ohio, the cribs
+of the water works, situated a mile and a quarter, five miles, and six
+miles out in Lake Erie are invaded by a regular plague of flies when the
+wind blows from the city. Investigation showed that there was absolutely
+nothing of any kind in which flies could breed on the crib.
+
+The omnivorous habits of the house-fly are matters of everyday
+observation. From our view point, it is sufficient to emphasize that
+from feeding on excrement, on sputum, on open sores, or on putrifying
+matter, the flies may pass to the food or milk upon the table or to
+healthy mucous membranes, or uncontaminated wounds. There is nothing in
+its appearance to tell whether the fly that comes blithely to sup with
+you is merely unclean, or whether it has just finished feeding upon
+dejecta teeming with typhoid bacilli.
+
+[Illustration: 100. Pulvillus of foot of house-fly, showing glandular
+hairs.]
+
+The method of feeding of the house-fly has an important bearing on the
+question of its ability to transmit pathogenic organisms. Graham-Smith
+(1910) has shown that when feeding, flies frequently moisten soluble
+substances with "vomit" which is regurgitated from the crop. This is, of
+course, loaded with bacteria from previous food. When not sucked up
+again these drops of liquid dry, and produce round marks with an opaque
+center and rim and an intervening less opaque area. Fly-specks, then,
+consist of both vomit spots and feces. Graham-Smith shows a photograph
+of a cupboard window where, on an area six inches square, there were
+counted eleven hundred and two vomit marks and nine fecal deposits.
+
+From a bacteriologist's viewpoint a discussion of the possibility of a
+fly's carrying bacteria would seem superfluous. Any exposed object,
+animate or inanimate, is contaminated by bacteria and will transfer them
+if brought into contact with suitable culture media, whether such
+substance be food, or drink, open wounds, or the sterile culture media
+of the laboratory. A needle point may convey enough germs to produce
+disease. Much more readily may the house-fly with its covering of hairs
+and its sponge-like pulvilli (fig. 109) pick up and transfer bits of
+filth and other contaminated material.
+
+For popular instruction this inevitable transfer of germs by the
+house-fly is strikingly demonstrated by the oft copied illustration of
+the tracks of a fly on a sterile culture plate. Two plates of gelatine
+or, better, agar medium are prepared. Over one of these a fly (with
+wings clipped) is allowed to walk, the other is kept as a check. Both
+are put aside at room temperature, to be examined after twenty-four to
+forty-eight hours. At the end of that time, the check plate is as clear
+as ever, the one which the fly has walked is dotted with colonies of
+bacteria and fungi. The value in the experiment consists in emphasizing
+that by this method we merely render visible what is constantly
+occurring in nature.
+
+A comparable experiment which we use in our elementary laboratory work
+is to take three samples of _clean_ (preferably, sterile) fresh milk in
+sterile bottles. One of them is plugged with a pledget of cotton, into
+the second is dropped a fly from the laboratory and into the third is
+dropped a fly which has been caught feeding upon garbage or other filth.
+After a minute or two the flies are removed and the vials plugged as was
+number one. The three are then set aside at room temperature. When
+examined after twenty-four hours the milk in the first vial is either
+still sweet or has a "clean" sour odor; that of the remaining two is
+very different, for it has a putrid odor, which is usually more
+pronounced in the case of sample number three.
+
+Several workers have carried out experiments to determine the number of
+bacteria carried by flies under natural conditions. One of the most
+extended and best known of these is the series by Esten and Mason
+(1908). These workers caught flies from various sources in a sterilized
+net, placed them in a sterile bottle and poured over them a known
+quantity of sterilized water, in which they were shaken so as to wash
+the bacteria from their bodies. They found the number of bacteria on a
+single fly to range from 550 to 6,600,000. Early in the fly season the
+numbers of bacteria on flies are comparatively small, while later the
+numbers are comparatively very large. The place where flies live also
+determines largely the numbers that they carry. The lowest number, 550,
+was from a fly caught in the bacteriological laboratory, the highest
+number, 6,600,000 was the average from eighteen swill-barrel flies.
+Torrey (1912) made examination of "wild" flies from a tenement house
+district of New York City. He found "that the surface contamination of
+these 'wild' flies may vary from 570 to 4,400,000 bacteria per insect,
+and the intestinal bacterial content from 16,000 to 28,000,000."
+
+Less well known in this country is the work of Cox, Lewis, and Glynn
+(1912). They examined over four hundred and fifty naturally infected
+house-flies in Liverpool during September and early October. Instead of
+washing the flies they were allowed to swim on the surface of sterile
+water for five, fifteen, or thirty minutes, thus giving natural
+conditions, where infection occurs from vomit and dejecta of the flies,
+as well as from their bodies. They found, as might be expected, that
+flies from either insanitary or congested areas of the city contain far
+more bacteria than those from the more sanitary, less congested, or
+suburban areas. The number of aerobic bacteria from the former varied
+from 800,000 to 500,000,000 per fly and from the latter from 21,000 to
+100,000. The number of intestinal forms conveyed by flies from
+insanitary or congested areas was from 10,000 to 333,000,000 as compared
+with from 100 to 10,000 carried by flies from the more sanitary areas.
+
+Pathogenic bacteria and those allied to the food poisoning group were
+only obtained from the congested or moderately congested areas and not
+from the suburban areas, where the chances of infestation were less.
+
+The interesting fact was brought out that flies caught in milk shops
+apparently carry and obtain more bacteria than those from other shops
+with exposed food in a similar neighborhood. The writers explained this
+as probably due to the fact that milk when accessible, especially during
+the summer months, is suitable culture medium for bacteria, and the
+flies first inoculate the milk and later reinoculate themselves, and
+then more of the milk, so establishing a vicious circle.
+
+They conclude that in cities where food is plentiful flies rarely
+migrate from the locality in which they are bred, and consequently the
+number of bacteria which they carry depends upon the general standard
+of cleanliness in that locality. Flies caught in a street of modern,
+fairly high class, workmen's dwellings forming a sanitary oasis in the
+midst of a slum area, carried far less bacteria than those caught in the
+adjacent neighborhood.
+
+Thus, as the amount of dirt carried by flies in any particular locality,
+measured in the terms of bacteria, bears a definite relation to the
+habits of the people and to the state of the streets, it demonstrates
+the necessity of efficient municipal and domestic cleanliness, if the
+food of the inhabitants is to escape pollution, not only with harmless
+but also with occasional pathogenic bacteria.
+
+The above cited work is of a general nature, but, especially in recent
+years, many attempts have been made to determine more specifically the
+ability of flies to transmit pathogenic organisms. The critical reviews
+of Nuttall and Jepson (1909), Howard (1911), and Graham-Smith (1913)
+should be consulted by the student of the subject. We can only cite here
+a few of the more striking experiments.
+
+Celli (1888) fed flies on pure cultures of _Bacillus typhosus_ and
+declared that he was able to recover these organisms from the intestinal
+contents and excrement.
+
+Firth and Horrocks (1902), cited by Nuttall and Jepson, "kept _Musca
+domestica_ (also bluebottles) in a large box measuring 4 x 3 x 3 feet,
+with one side made of glass. They were fed on material contaminated with
+cultures of _B. typhosus_. Agar plates, litmus, glucose broth and a
+sheet of clean paper were at the same time exposed in the box. After a
+few days the plates and broth were removed and incubated with a positive
+result." Graham-Smith (1910) "carried out experiments with large numbers
+of flies kept in gauze cages and fed for eight hours on emulsions of _B.
+typhosus_ in syrup. After that time the infested syrup was removed and
+the flies were fed on plain syrup. _B. typhosus_ was isolated up to 48
+hours (but not later) from emulsions of their feces and from plates over
+which they walked."
+
+Several other workers, notably Hamilton (1903), Ficker (1903),
+Bertarelli (1910) Faichnie (1909), and Cochrane (1912), have isolated
+_B. typhosus_ from "wild" flies, naturally infected. The papers of
+Faichnie and of Cochrane we have not seen, but they are quoted in
+_extenso_ by Graham-Smith (1913).
+
+On the whole, the evidence is conclusive that typhoid germs not only may
+be accidentally carried on the bodies of house-flies but may pass
+through their bodies and be scattered in a viable condition in the feces
+of the fly for at least two days after feeding. Similar, results have
+been reached in experiments with cholera, tuberculosis and yaws, the
+last-mentioned being a spirochaete disease. Darling (1913) has shown that
+murrina, a trypanosome disease of horses and mules in the Canal zone is
+transmitted by house-flies which feed upon excoriated patches of
+diseased animals and then pass to cuts and galls of healthy animals.
+
+Since it is clear that flies are abundantly able to disseminate viable
+pathogenic bacteria, it is important to consider whether they have
+access to such organisms in nature. A consideration of the method of
+spread of typhoid will serve to illustrate the way in which flies may
+play an important role.
+
+Typhoid fever is a specific disease caused by _Bacillus typhosus_, and
+by it alone. The causative organism is to be found in the excrement and
+urine of patients suffering from the disease. More than that, it is
+often present in the dejecta for days, weeks, or even months and years,
+after the individual has recovered from the disease. Individuals so
+infested are known as "typhoid carriers" and they, together with those
+suffering from mild cases, or "walking typhoid," are a constant menace
+to the health of the community in which they are found.
+
+Human excrement is greedily visited by flies, both for feeding and for
+ovipositing. The discharges of typhoid patients, or of chronic
+"carriers," when passed in the open, in box privies, or camp latrines,
+or the like, serve to contaminate myriads of the insects which may then
+spread the germ to human food and drink. Other intestinal diseases may
+be similarly spread. There is abundant epidaemiological evidence that
+infantile diarrhoea, dysentery, and cholera may be so spread.
+
+Stiles and Keister (1913) have shown that spores of _Lamblia
+intestinalis_, a flagellate protozoan living in the human intestine, may
+be carried by house-flies. Though this species is not normally
+pathogenic, one or more species of _Entamoeba_ are the cause of a type
+of a highly fatal tropical dysentery. Concerning it, and another
+protozoan parasite of man, they say, "If flies can carry _Lamblia_
+spores measuring 10 to 7u, and bacteria that are much smaller, and
+particles of lime that are much larger, there is no ground to assume
+that flies may not carry _Entamoeba_ and _Trichomonas_ spores."
+
+Tuberculosis is one of the diseases which it is quite conceivable may be
+carried occasionally. The sputum of tubercular patients is very
+attractive to flies, and various workers, notably Graham-Smith, have
+found that _Musca domestica_ may distribute the bacillus for several
+days after feeding on infected material.
+
+A type of purulent opthalmia which is very prevalent in Egypt is often
+said to be carried by flies. Nuttall and Jepson (1909) consider that the
+evidence regarding the spread of this disease by flies is conclusive and
+that the possibility of gonorrhoeal secretions being likewise conveyed
+cannot be denied.
+
+Many studies have been published, showing a marked agreement between the
+occurrence of typhoid and other intestinal diseases and the prevalence
+of house-flies. The most clear-cut of these are the studies of the Army
+Commission appointed to investigate the cause of epidemics of enteric
+fever in the volunteer camps in the Southern United States during the
+Spanish-American War. Though their findings as presented by Vaughan
+(1909), have been quoted very many times, they are so germane to our
+discussion that they will bear repetition:
+
+"Flies swarmed over infected fecal matter in the pits and fed upon the
+food prepared for the soldiers in the mess tents. In some instances
+where lime had recently been sprinkled over the contents of the pits,
+flies with their feet whitened with lime were seen walking over the
+food." Under such conditions it is no wonder that "These pests had
+inflicted greater loss upon American soldiers than the arms of Spain."
+
+Similar conditions prevailed in South Africa during the Boer War. Seamon
+believes that very much of the success of the Japanese in their fight
+against Russia was due to the rigid precautions taken to prevent the
+spread of disease by these insects and other means.
+
+Veeder has pointed out that the characteristics of a typical fly-borne
+epidemic of typhoid are that it occurs in little neighborhood epidemics,
+extending by short leaps from house to house, without regard to water
+supply or anything else in common. It tends to follow the direction of
+prevailing winds (cf. the conclusions of Hindle and Merriman). It occurs
+during warm weather. Of course, when the epidemic is once well under
+way, other factors enter into its spread.
+
+In general, flies may be said to be the chief agency in the spread of
+typhoid in villages and camps. In cities with modern sewer systems they
+are less important, though even under the best of such conditions, they
+are important factors. Howard has emphasized that in such cities there
+are still many uncared-for box privies and that, in addition, the
+deposition of feces overnight in uncared-for waste lots and alleys is
+common.
+
+Not only unicellular organisms, such as bacteria and protozoa, but also
+the eggs, embryos and larvae of parasitic worms have been found to be
+transported by house-flies. Ransom (1911) has found that _Habronema
+muscae_, a nematode worm often found in adult flies, is the immature
+stage of a parasite occurring in the stomach of the horse. The eggs or
+embryos passing out with the feces of the horse, are taken up by fly
+larvae and carried over to the imago stage.
+
+Grassi (1883), Stiles (1889), Calandruccio (1906), and especially Nicoll
+(1911), have been the chief investigators of the ability of house-flies
+to carry the ova and embryos of human intestinal parasites. Graham-Smith
+(1913) summarizes the work along this line as follows:
+
+"It is evident from the investigations that have been quoted that
+house-flies and other species are greatly attracted to the ova of
+parasitic worms contained in feces and other materials, and make great
+efforts to ingest them. Unless the ova are too large they often succeed,
+and the eggs are deposited uninjured in their feces, in some cases up to
+the third day at least. The eggs may also be carried on their legs or
+bodies. Under suitable conditions, food and fluids may be contaminated
+with the eggs of various parasitic worms by flies, and in one case
+infection of the human subject has been observed. Feces containing
+tape-worm segments may continue to be a source of infection for as long
+as a fortnight. Up to the present, however, there is no evidence to show
+what part flies play in the dissemination of parasitic worms under
+natural conditions."
+
+Enough has been said to show that the house-fly must be dealt with as a
+direct menace to public health. Control measures are not merely matters
+of convenience but are of vital importance.
+
+Under present conditions the speedy elimination of the house-fly is
+impossible and the first thing to be considered is methods of protecting
+food and drink from contamination. The first of these methods is the
+thorough screening of doors and windows to prevent the entrance of
+flies. In the case of kitchen doors, the flies, attracted by odors, are
+likely to swarm onto the screen and improve the first opportunity for
+gaining an entrance. This difficulty can be largely avoided by
+screening-in the back porch and placing the screen door at one end
+rather than directly before the door.
+
+The use of sticky fly paper to catch the pests that gain entrance to the
+house is preferable to the various poisons often used. Of the latter,
+formalin (40 per cent formaldehyde) in the proportion of two
+tablespoonfuls to a pint of water is very efficient, if all other
+liquids are removed or covered, so that the flies must depend on the
+formalin for drink. The mixture is said to be made more attractive by
+the addition of sugar or milk, though we have found the plain solution
+wholly satisfactory, under proper conditions. It should be emphasized
+that this formalin mixture is not perfectly harmless, as so often
+stated. There are on record cases of severe and even fatal poisoning
+from the accidental drinking of solutions.
+
+When flies are very abundant in a room they can be most readily gotten
+rid of by fumigation with sulphur, or by the use of pure pyrethrum
+powder either burned or puffed into the air. Herrick (1913) recommends
+the following method: "At night all the doors and windows of the kitchen
+should be closed; fresh powder should be sprinkled over the stove, on
+the window ledges, tables, and in the air. In the morning flies will be
+found lying around dead or stupified. They may then be swept up and
+burned." This method has proved very efficaceous in some of the large
+dining halls in Ithaca.
+
+The writers have had little success in fumigating with the vapors of
+carbolic acid, or carbolic acid and gum camphor, although these methods
+will aid in driving flies from a darkened room.
+
+All of these methods are but makeshifts. As Howard has so well put it,
+"the truest and simplest way of attacking the fly problem is to prevent
+them from breeding, by the treatment or abolition of all places in which
+they can breed. To permit them to breed undisturbed and in countless
+numbers, and to devote all our energy to the problem of keeping them out
+of our dwellings, or to destroy them after they have once entered in
+spite of all obstacles, seems the wrong way to go about it."
+
+We have already seen that _Musca domestica_ breeds in almost any
+fermenting organic material. While it prefers horse manure, it breeds
+also in human feces, cow dung and that of other animals, and in refuse
+of many kinds. To efficiently combat the insect, these breeding places
+must be removed or must be treated in some such way as to render them
+unsuitable for the development of the larvae. Under some conditions
+individual work may prove effective, but to be truly efficient there
+must be extensive and thorough cooperative efforts.
+
+Manure, garbage, and the like should be stored in tight receptacles and
+carted away at least once a week. The manure may be carted to the fields
+and spread. Even in spread manure the larvae may continue their
+development. Howard points out that "it often happens that after a lawn
+has been heavily manured in early summer the occupants of the house will
+be pestered with flies for a time, but finding no available breeding
+place these disappear sooner or later. Another generation will not breed
+in the spread manure."
+
+Hutchinson (1914) has emphasized that the larvae of houseflies have
+deeply engrained the habit of migrating in the prepupal stage and has
+shown that this offers an important point of attack in attempts to
+control the pest. He has suggested that maggot traps might be developed
+into an efficient weapon in the warfare against the house-fly. Certain
+it is that the habit greatly simplifies the problem of treating the
+manure for the purpose of killing the larvae.
+
+There have been many attempts to find some cheap chemical which would
+destroy fly larvae in horse manure without injuring the bacteria or
+reducing the fertilizing values of the manure. The literature abounds in
+recommendations of kerosene, lime, chloride of lime, iron sulphate, and
+other substances, but none of them has met the situation. The whole
+question has been gone into thoroughly by Cook, Hutchinson and Scales
+(1914), who tested practically all of the substances which have been
+recommended. They find that by far the most effective, economical, and
+practical of the substances is borax in the commercial form in which it
+is available throughout the country.
+
+"Borax increases the water-soluble nitrogen, ammonia and alkalinity of
+manure and apparently does not permanently injure the bacterial flora.
+The application of manure treated with borax at the rate of 0.62 pound
+per eight bushels (10 cubic feet) to soil does not injure the plants
+thus far tested, although its cumulative effect, if any, has not been
+determined."
+
+As their results clearly show that the substances so often recommended
+are inferior to borax, we shall quote in detail their directions for
+treating manure so as to kill fly eggs and maggots.
+
+"Apply 0.62 pound borax or 0.75 pound calcined colemanite to every 10
+cubic feet (8 bushels) of manure immediately on its removal from the
+barn. Apply the borax particularly around the outer edges of the pile
+with a flour sifter or any fine sieve, and sprinkle two or three gallons
+of water over the borax-treated manure.
+
+"The reason for applying the borax to the fresh manure immediately after
+its removal from the stable is that the flies lay their eggs on the
+fresh manure, and borax, when it comes in contact with the eggs,
+prevents their hatching. As the maggots congregate at the outer edge of
+the pile, most of the borax should be applied there. The treatment
+should be repeated with each addition of fresh manure, but when the
+manure is kept in closed boxes, less frequent applications will be
+sufficient. When the calcined colemanite is available, it may be used at
+the rate of 0.75 pound per 10 cubic feet of manure, and is a cheaper
+means of killing the maggots. In addition to the application of borax to
+horse manure to kill fly larvae, it may be applied in the same proportion
+to other manures, as well as to refuse and garbage. Borax may also be
+applied to the floors and crevices in barns, stables, markets, etc., as
+well as to street sweepings, and water should be added as in the
+treatment of horse manure. After estimating the amount of material to be
+treated and weighing the necessary amount of borax, a measure may be
+used which will hold the proper amount, thus avoiding the subsequent
+weighings.
+
+"While it can be safely stated that no injurious action will follow the
+application of manure treated with borax at the rate of 0.62 pound for
+eight bushels, or even larger amounts in the case of some plants,
+nevertheless the borax-treated manure has not been studied in connection
+with the growth of all crops, nor has its cumulative effect been
+determined. It is therefore recommended that not more than 15 tons per
+acre of the borax-treated manure should be applied to the field. As
+truckmen use considerably more than this amount, it is suggested that
+all cars containing borax-treated manure be so marked, and that
+public-health officials stipulate in their directions for this treatment
+that not over 0.62 pound for eight bushels of manure be used, as it has
+been shown that larger amounts of borax will injure most plants. It is
+also recommended that all public-health officials and others, in
+recommending the borax treatment for killing fly eggs and maggots in
+manure, warn the public against the injurious effects of large amounts
+of borax on the growth of plants."
+
+"The amount of manure from a horse varies with the straw or other
+bedding used, but 12 or 15 bushels per week represent the approximate
+amount obtained. As borax costs from five to six cents per pound in
+100-pound lots in Washington, it will make the cost of the borax
+practically one cent per horse, per day. And if calcined colemanite is
+purchased in large shipments the cost should be considerably less."
+
+Hodge (1910) has approached the problem of fly extermination from
+another viewpoint. He believes that it is practical to trap flies out of
+doors during the preoviposition period, when they are sexually immature,
+and to destroy such numbers of them that the comparatively few which
+survive will not be able to lay eggs in sufficient numbers to make the
+next generation a nuisance. To the end of capturing them in enormous
+numbers he has devised traps to be fitted over garbage cans, into stable
+windows, and connected with the kitchen window screens. Under some
+conditions this method of attack has proved very satisfactory.
+
+One of the most important measures for preventing the spread of disease
+by flies is the abolition of the common box privy. In villages and rural
+districts this is today almost the only type to be found. It is the
+chief factor in the spread of typhoid and other intestinal diseases, as
+well as intestinal parasites. Open and exposed to myriads of flies which
+not only breed there but which feed upon the excrement, they furnish
+ideal conditions for spreading contamination. Even where efforts are
+made to cover the contents with dust, or ashes, or lime, flies may
+continue to breed unchecked. Stiles and Gardner have shown that
+house-flies buried in a screened stand-pipe forty-eight inches under
+sterile sand came to the surface. Other flies of undetermined species
+struggled up through seventy-two inches of sand.
+
+So great is the menace of the ordinary box privy that a number of
+inexpensive and simple sanitary privies have been designed for use where
+there are not modern sewer systems. Stiles and Lumsden (1911) have given
+minute directions for the construction of one of the best types, and
+their bulletin should be obtained by those interested.
+
+Another precaution which is of fundamental importance in preventing the
+spread of typhoid, is that of disinfecting all discharges from patients
+suffering with the disease. For this purpose, quick-lime is the cheapest
+and is wholly satisfactory. In chamber vessels it should be used in a
+quantity equal to that of the discharge to be treated. It should be
+allowed to act for two hours. Air-slaked lime is of no value whatever.
+Chloride of lime, carbolic acid, or formalin may be used, but are more
+expensive. Other intestinal diseases demand similar precautions.
+
+
+STOMOXYS CALCITRANS, THE STABLE-FLY--It is a popular belief that
+house-flies bite more viciously just before a rain. As a matter of
+fact, the true house-flies never bite, for their mouth-parts are not
+fitted for piercing. The basis of the misconception is the fact that a
+true biting fly, _Stomoxys calcitrans_ (fig. 110), closely resembling
+the house-fly, is frequently found in houses and may be driven in in
+greater numbers by muggy weather. From its usual habitat this fly is
+known as the "stable-fly" or, sometimes as the "biting house-fly."
+
+_Stomoxys calcitrans_ may be separated from the house-fly by the use of
+the key on p. 145. It may be more fully characterized as follows:
+
+The eyes of the male are separated by a distance equal to one-fourth of
+the diameter of the head, in the female by one-third. The frontal stripe
+is black, the cheeks and margins of the orbits silvery-white. The
+antennae are black, the arista feathered on the upper side only. The
+proboscis is black, slender, fitted for piercing and projects forward in
+front of the head. The thorax is grayish, marked by four conspicuous,
+more or less complete black longitudinal stripes; the scutellum is
+paler; the macrochaetae are black. The abdomen is gray, dorsally with
+three brown spots on the second and third segments and a median spot on
+the fourth. These spots are more pronounced in the female. The legs are
+black, the pulvilli distinct. The wings are hyaline, the vein M_{1+2}
+less sharply curved than in the house-fly, the apical cell being thus
+more widely open (cf. fig. 110). Length 7 mm.
+
+[Illustration: 110. Stomoxys calcitrans; adult, larva, puparium and
+details, (x5). After Howard.]
+
+This fly is widely distributed, being found the world over. It was
+probably introduced into the United States, but has spread to all parts
+of the country. Bishopp (1913) regards it as of much more importance as
+a pest of domestic animals in the grain belt than elsewhere in the
+United States. The life-history and habits of this species have assumed
+a new significance since it has been suggested that it may transmit the
+human diseases, infantile paralysis and pellagra. In this country, the
+most detailed study of the fly is that of Bishopp (1913) whose data
+regarding the life cycle are as follows:
+
+The eggs like those of the house-fly, are about one mm. in length. Under
+a magnifying glass they show a distinct furrow along one side. When
+placed on any moist substance they hatch in from one to three days after
+being deposited.
+
+The larva or maggots (fig. 110) have the typical shape and actions of
+most maggots of the Muscid group. They can be distinguished from those
+of the house-fly as the stigma-plates are smaller, much further apart,
+with the slits less sinuous. Development takes place fairly rapidly when
+the proper food conditions are available and the growth is completed
+within eleven to thirty or more days.
+
+The pupa (fig. 110), like that of related flies, undergoes its
+development within the contracted and hardened last larval skin, or
+puparium. This is elongate oval, slightly thicker towards the head end,
+and one-sixth to one-fourth of an inch in length. The pupal stage
+requires six to twenty days, or in cool weather considerably longer.
+
+The life-cycle of the stable-fly is therefore considerably longer than
+that of _Musca domestica_. Bishopp found that complete development might
+be undergone in nineteen days, but that the average period was somewhat
+longer, ranging from twenty-one to twenty-five days, where conditions
+are very favorable. The longest period which he observed was forty-three
+days, though his finding of full grown larvae and pupae in straw during
+the latter part of March, in Northern Texas, showed that development may
+require about three months, as he considered that these stages almost
+certainly developed from eggs deposited the previous December.
+
+The favorite breeding place, where available, seems to be straw or
+manure mixed with straw. It also breeds in great numbers in
+horse-manure, in company with _Musca domestica_.
+
+Newstead considers that in England the stable-fly hibernates in the
+pupal stage. Bishopp finds that in the southern part of the United
+States there is no true hibernation, as the adults have been found to
+emerge at various times during the winter. He believes that in the
+northern United States the winter is normally passed in the larval and
+pupal stages, and that the adults which have been observed in heated
+stables in the dead of winter were bred out in refuse within the warm
+barns and were not hibernating adults.
+
+Graham-Smith (1913) states that although the stable-fly frequents stable
+manure, it is probably not an important agent in distributing the
+organisms of intestinal diseases. Bishopp makes the important
+observation that "it has never been found breeding in human excrement
+and does not frequent malodorous places, which are so attractive to the
+house-fly. Hence it is much less likely to carry typhoid and other germs
+which may be found in such places."
+
+Questions of the possible agency of _Stomoxys calcitrans_ in the
+transmission of infantile paralysis and of pellagra, we shall consider
+later.
+
+
+OTHER ARTHROPODS WHICH MAY SERVE AS SIMPLE CARRIERS OF PATHOGENIC
+ORGANISMS--It should be again emphasized that any insect which has
+access to, and comes in contact with, pathogenic organisms and then
+passes to the food, or drink, or the body of man, may serve as a simple
+carrier of disease. In addition to the more obvious illustrations, an
+interesting one is the previously cited case of the transfer of
+_Dermatobia cyaniventris_ by a mosquito (fig. 81-84). Darling (1913) has
+shown that in the tropics, the omnipresent ants may be important factors
+in the spread of disease.
+
+
+
+
+CHAPTER VI
+
+ARTHROPODS AS DIRECT INOCULATORS OF DISEASE GERMS
+
+
+We have seen that any insect which, like the house-fly, has access to
+disease germs and then comes into contact with the food or drink of man,
+may serve to disseminate disease. Moreover, it has been clearly
+established that a contaminated insect, alighting upon wounded or
+abraded surfaces, may infect them. These are instances of mere
+accidental, mechanical transfer of pathogenic organisms.
+
+Closely related are the instances of direct inoculation of disease germs
+by insects and other arthropods. In this type, a blood-sucking species
+not only takes up the germs but, passing to a healthy individual, it
+inserts its contaminated mouth-parts and thus directly inoculates its
+victim. In other words, the disease is transferred just as blood
+poisoning may be induced by the prick of a contaminated needle, or as
+the laboratory worker may inoculate an experimental animal.
+
+Formerly, it was supposed that this method of the transfer of disease by
+arthropods was a very common one and many instances are cited in the
+earlier literature of the subject. It is, however, difficult to draw a
+sharp line between such cases and those in which, on the one hand, the
+arthropod serves as a mere passive carrier or, on the other hand, serves
+as an essential host of the pathogenic organism. More critical study of
+the subject has led to the belief that the importance of the role of
+arthropods as direct inoculators has been much overestimated.
+
+The principal reason for regarding this phase of the subject as
+relatively unimportant, is derived from a study of the habits of the
+blood-sucking species. It is found that, in general, they are
+intermittent feeders, visiting their hosts at intervals and then
+abstaining from feeding for a more or less extended period, while
+digesting their meal. In the meantime, most species of bacteria or of
+protozoan parasites with which they might have contaminated their
+mouth-parts, would have perished, through inability to withstand drying.
+
+In spite of this, it must be recognized that this method of transfer
+does occur and must be reckoned with in any consideration of the
+relations of insects to disease. We shall first cite some general
+illustrations and shall then discuss the role of fleas in the spreading
+of bubonic plague, an illustration which cannot be regarded as typical,
+since it involves more than mere passive carriage.
+
+
+SOME ILLUSTRATIONS OF DIRECT INOCULATION OF DISEASE GERMS BY ARTHROPODS
+
+In discussing poisonous arthropods, we have already emphasized that
+species which are of themselves innocuous to man, may occasionally
+introduce bacteria by their bite or sting and thus cause more or less
+severe secondary symptoms. That such cases should occur, is no more than
+is to be expected. The mouth-parts or the sting of the insect are not
+sterile and the chances of their carrying pyogenic organisms are always
+present.
+
+More strictly falling in the category of transmission of disease germs
+by direct inoculation are the instances where the insect, or related
+form, feeds upon a diseased animal and passes promptly to a healthy
+individual which it infects. Of such a nature are the following:
+
+Various species of biting flies are factors in the dissemination of
+anthrax, an infectious and usually fatal disease of animals and,
+occasionally, of man. That the bacteria with which the blood of diseased
+animals teem shortly before death might be transmitted by such insects
+has long been contended, but the evidence in support of the view has
+been unsatisfactory. Recently, Mitzmain (1914) has reported a series of
+experiments which show conclusively that the disease may be so conveyed
+by a horse-fly, _Tabanus striatus_, and by the stable-fly, _Stomoxys
+calcitrans_.
+
+Mitzmain's experiments were tried with an artificially infected guinea
+pig, which died of the disease upon the third day. The flies were
+applied two and one-half hours, to a few minutes, before the death of
+the animal. With both species the infection was successfully transferred
+to healthy guinea pigs by the direct method, in which the flies were
+interrupted while feeding on the sick animal. The evidence at hand does
+not warrant the conclusion that insect transmission is the rule in the
+case of this disease.
+
+The nagana, or tsetse-fly disease of cattle is the most virulent disease
+of domestic animals in certain parts of Africa. It is caused by a
+protozoan blood parasite, _Trypanosoma brucei_, which is conveyed to
+healthy animals by the bite of _Glossina morsitans_ and possibly other
+species of tsetse-flies. The flies remain infective for forty-eight
+hours after feeding on a diseased animal. The insect also serves as an
+essential host of the parasite.
+
+Surra, a similar trypanosomiasis affecting especially horses and mules,
+occurs in southern Asia, Malaysia, and the Philippines where the
+tsetse-flies are not to be found. It is thought to be spread by various
+species of blood-sucking flies belonging to the genera _Stomoxys_,
+_Haematobia_, and _Tabanus_. Mitzmain (1913) demonstrated that in the
+Philippines it is conveyed mechanically by _Tabanus striatus_.
+
+The sleeping sickness of man, in Africa, has also been supposed to be
+directly inoculated by one, or several, species of tsetse-flies. It is
+now known that the fly may convey the disease for a short time after
+feeding, but that there is then a latent period of from fourteen to
+twenty-one days, after which it again becomes infectious. This indicates
+that in the meantime the parasite has been undergoing some phase of its
+life-cycle and that the fly serves as an intermediate host. We shall
+therefore consider it more fully under that grouping.
+
+These are a few of the cases of direct inoculation which may be cited as
+of the simpler type. We shall next consider the role of the flea in the
+dissemination of the bubonic plague, an illustration complicated by the
+fact that the bacillus multiples within the insect and may be indirectly
+inoculated.
+
+
+THE ROLE OF FLEAS IN THE TRANSMISSION OF THE PLAGUE
+
+The plague is a specific infectious disease caused by _Bacillus pestis_.
+It occurs in several forms, of which the bubonic and the pneumonic are
+the most common. According to Wyman, 80 per cent of the human cases are
+of the bubonic type. It is a disease which, under the name of oriental
+plague, the pest, or the black death, has ravaged almost from time
+immemorial the countries of Africa, Asia, and Europe. The record of its
+ravages are almost beyond belief. In 542 A. D. it caused in one day ten
+thousand deaths in Constantinople. In the 14th century it was introduced
+from the East and prevailed throughout Armenia, Asia Minor, Egypt and
+Northern Africa and Europe. Hecker estimates that one-fourth of the
+population of Europe, or twenty-five million persons, died in the
+epidemic of that century. From then until the 17th century it was almost
+constantly present in Europe, the great plague of London, in 1665
+killing 68,596 out of a population of 460,000. Such an epidemic would
+mean for New York City a proportionate loss of over 600,000 in a single
+year. It is little wonder that in the face of such an appalling disaster
+suspicion and credulity were rife and the wildest demoralization ensued.
+
+During the 14th century the Jews were regarded as responsible for the
+disease, through poisoning wells, and were subjected to the most
+incredible persecution and torture. In Milan the visitation of 1630 was
+credited to the so-called anointers,--men who were supposed to spread
+the plague by anointing the walls with magic ointment--and the most
+horrible tortures that human ingenuity could devise were imposed on
+scores of victims, regardless of rank or of public service (fig. 112,
+a). Manzoni's great historical novel, "The Betrothed" has well pictured
+conditions in Italy during this period.
+
+[Illustration: 111. A contemporaneous engraving of the pest hospital in
+Vienna in 1679. After Peters.]
+
+In modern times the plague is confined primarily to warm climates, a
+condition which has been brought about largely through general
+improvement in sanitary conditions.
+
+At present, the hotbed of the disease is India, where there were
+1,040,429 deaths in 1904 and where in a period of fifteen years, ending
+with January 1912, there were over 15,000,000 deaths. The reported
+deaths in that country for 1913 totaled 198,875.
+
+During the winter of 1910-11 there occurred in Manchuria and North China
+a virulent epidemic of the pneumonic plague which caused the death of
+nearly 50,000 people. The question as to its origin and means of spread
+will be especially referred to later.
+
+[Illustration: 112 a. A medieval method of combating the plague. The
+persecution of the anointers in Milan in 1630. From a copy of "Il
+processi originale degli untori" in the library of Cornell University.]
+
+Until recent years, the plague had not been known to occur in the New
+World but there were outbreaks in Brazil and Hawaii in 1899, and in 1900
+there occurred the first cases in San Francisco. In California there
+were 125 cases in the period 1900-04; three cases in the next three
+years and then from May 1907 to March 1908, during the height of the
+outbreak, 170 cases. Since that time there have been only sporadic
+cases, the last case reported being in May 1914. Still more recent were
+the outbreaks in the Philippine Islands, Porto Rico, and Cuba.
+
+On June 24, 1914, there was recognized a case of human plague in New
+Orleans. The Federal Health Service immediately took charge, and
+measures for the eradication of the disease were vigorously enforced. Up
+to October 10, 1914 there had been reported 30 cases of the disease in
+man, and 181 cases of plague in rats.
+
+[Illustration: 112 b. The modern method of combating the plague. A day's
+catch of rats in the fight against plague in San Francisco. Courtesy of
+Review of Reviews.]
+
+The present-day methods of combating bubonic plague are well illustrated
+by the fight in San Francisco. Had it not been for the strenuous and
+radical anti-plague campaign directed by the United States Marine
+Hospital Service we might have had in our own country an illustration of
+what the disease can accomplish. On what newly acquired knowledge was
+this fight based?
+
+The basis was laid in 1894, when the plague bacillus was first
+discovered. All through the centuries, before and during the Christian
+era, down to 1894, the subject was enveloped in darkness and there had
+been a helpless, almost hopeless struggle in ignorance on the part of
+physicians, sanitarians, and public health officials against the ravages
+of this dread disease. Now its cause, method of propagation and means to
+prevent its spread are matters of scientific certainty.
+
+After the discovery of the causative organism, one of the first advances
+was the establishment of the identity of human plague and that of
+rodents. It had often been noted that epidemics of the human disease
+were preceded by great epizootics among rats and mice. So well
+established was this fact that with the Chinese, unusual mortality among
+these rodents was regarded as foretelling a visitation of the human
+disease. That there was more than an accidental connection between the
+two was obvious when Yersin, the discoverer of _Bacillus pestis_,
+announced that during an epidemic the rats found dead in the houses and
+in the streets almost always contain the bacillus in great abundance in
+their organs, and that many of them exhibit veritable buboes.
+
+Once it was established that the diseases were identical, the attention
+of the investigators was directed to a study of the relations between
+that of rats and of humans, and evidence accumulated to show that the
+bubonic plague was primarily a disease of rodents and that in some
+manner it was conveyed from them to man.
+
+There yet remained unexplained the method of transfer from rat to man.
+As long ago as the 16th century, Mercuralis suggested that house-flies
+were guilty of disseminating the plague but modern investigation, while
+blaming the fly for much in the way of spreading disease, show that it
+is an insignificant factor in this case.
+
+Search for blood-sucking insects which would feed on both rodents and
+man, and which might therefore be implicated, indicated that the fleas
+most nearly met the conditions. At first it was urged that rat fleas
+would not feed upon man and that the fleas ordinarily attacking man
+would not feed upon rats. More critical study of the habits of fleas
+soon showed that these objections were not well-founded. Especially
+important was the evidence that soon after the death of their host, rat
+fleas deserted its body and might then become a pest in houses where
+they had not been noticed before.
+
+Attention was directed to the fact that while feeding, fleas are in the
+habit of squirting blood from the anus and that in the case of those
+which had fed upon rats and mice dying of the plague, virulent plague
+bacilli were to be found in such blood. Liston (1905) even found, and
+subsequent investigations confirmed, that the plague bacilli multiply in
+the stomach of the insect and that thus the blood ejected was richer in
+the organisms than was that of the diseased animal. It was found that a
+film of this infected blood spread out under the body of the flea and
+that thus the bacilli might be inoculated by the bite of the insect and
+by scratching.
+
+Very recently, Bacot and Martin (1914) have paid especial attention to
+the question of the mechanism of the transmission of the plague bacilli
+by fleas. They believe that plague infested fleas regurgitate blood
+through the mouth, and that under conditions precluding the possibility
+of infection by dejecta, the disease may be thus transmitted. The
+evidence does not seem sufficient to establish that this is the chief
+method of transmission.
+
+Conclusive experimental proof that fleas transmit the disease is further
+available from a number of sources. The most extensive series of
+experiments is that of the English Plague Commission in India, which
+reported in 1906 that:
+
+On thirty occasions a healthy rat contracted plague in sequence of
+living in the neighborhood of a plague infected rat under circumstances
+which prevented the healthy rat coming in contact with either the body
+or excreta of the diseased animal.
+
+In twenty-one experiments out of thirty-eight, healthy rats living in
+flea-proof cages contracted plague when exposed to rat fleas
+(_Xenopsylla cheopis_), collected from rats dead or dying of septicaemic
+plague.
+
+Close contact of plague-infected with healthy animals, if fleas are
+excluded, does not give rise to an epizootic among the latter. As the
+huts were never cleaned out, close contact included contact with feces
+and urine of infected animals, and contact with, and eating of food
+contaminated with feces and urine of infected animals, as well as pus
+from open plague ulcers. Close contact of young, even when suckled by
+plague-infected mothers, did not give the disease to the former.
+
+If fleas are present, then the epizootic, once started, spreads from
+animal to animal, the rate of progress being in direct proportion to the
+number of fleas.
+
+Aerial infection was excluded. Thus guinea-pigs suspended in a cage two
+feet above the ground did not contract the disease, while in the same
+hut those animals allowed to run about and those placed two inches above
+the floor became infected. It had previously been found that a rat flea
+could not hop farther than about five inches.
+
+Guinea pigs and monkeys were placed in plague houses in pairs, both
+protected from soil contact infection and both equally exposed to aerial
+infection, but one surrounded with a layer of tangle-foot paper and the
+other surrounded with a layer of sand. The following observations were
+made:
+
+(_a_) Many fleas were caught in the tangle-foot, a certain proportion of
+which were found on dissection to contain in their stomachs abundant
+bacilli microscopically identical with plague bacilli. Out of
+eighty-five human fleas dissected only one contained these bacilli,
+while out of seventy-seven rat fleas twenty-three were found thus
+infected.
+
+(_b_) The animals surrounded with tangle-foot in no instance developed
+plague, while several (24 per cent) of the non-protected animals died of
+the disease.
+
+Thus, the experimental evidence that fleas transmit the plague from rat
+to rat, from rats to guinea pigs, and from rats to monkeys is
+indisputable. There is lacking direct experimental proof of its transfer
+from rodents to man but the whole chain of indirect evidence is so
+complete that there can be no doubt that such a transfer does occur so
+commonly that in the case of bubonic plague it must be regarded as the
+normal method.
+
+Rats are not the only animals naturally attacked by the plague but as
+already suggested, it occurs in various other rodents. In California the
+disease has spread from rats to ground squirrels (_Otospermophilus
+beecheyi_), a condition readily arising from the frequency of
+association of rats with the squirrels in the neighborhood of towns, and
+from the fact that the two species of fleas found on them are also found
+on rats. While the danger of the disease being conveyed from squirrels
+to man is comparatively slight, the menace in the situation is that the
+squirrels may become a more or less permanent reservoir of the disease
+and infect rats, which may come into more frequent contact with man.
+
+The tarbagan (_Arctomys bobac_), is a rodent found in North Manchuria,
+which is much prized for its fur. It is claimed that this animal is
+extremely susceptible to the plague and there is evidence to indicate
+that it was the primary source of the great outbreak of pneumonic plague
+which occurred in Manchuria and North China during the winter of
+1910-11.
+
+Of fleas, any species which attacks both rodents and man may be an agent
+in the transmission of the plague. We have seen that in India the
+species most commonly implicated is the rat flea, _Xenopsylla cheopis_,
+(= _Loemopsylla_ or _Pulex cheopis_) (fig. 89). This species has also
+been found commonly on rats in San Francisco. The cat flea,
+_Ctenocephalus felis_, the dog flea, _Ctenocephalus canis_, the human
+flea, _Pulex irritans_, the rat fleas, _Ceratophyllus fasciatus_ and
+_Ctenopsyllus musculi_ have all been shown to meet the conditions.
+
+But, however clear the evidence that fleas are the most important agent
+in the transfer of plague, it is a mistake fraught with danger to assume
+that they are the only factor in the spread of the disease. The
+causative organism is a bacillus and is not dependent upon any insect
+for the completion of its development.
+
+Therefore, any blood-sucking insect which feeds upon a plague infected
+man or animal and then passes to a healthy individual, conceivably might
+transfer the bacilli. Verjbitski (1908) has shown experimentally that
+bed-bugs may thus convey the disease. Hertzog found the bacilli in a
+head-louse, _Pediculus humanus_, taken from a child which had died from
+the plague, and McCoy found them in a louse taken from a plague-infected
+squirrel. On account of their stationary habits, the latter insects
+could be of little significance in spreading the disease.
+
+Contaminated food may also be a source of danger. While this source,
+formerly supposed to be the principal one, is now regarded as
+unimportant, there is abundant experimental evidence to show that it
+cannot be disregarded. It is believed that infection in this way can
+occur only when there is some lesion in the alimentary canal.
+
+Still more important is the proof that in pneumonic plague the patient
+is directly infective and that the disease is spread from man to man
+without any intermediary. Especially conclusive is the evidence obtained
+by Drs. Strong and Teague during the Manchurian epidemic of 1910-11.
+They found that during coughing, in pneumonic plague cases, even when
+sputum visible to the naked eye is not expelled, plague bacilli in large
+numbers may become widely disseminated into the surrounding air. By
+exposing sterile plates before patients who coughed a single time, very
+numerous colonies of the bacillus were obtained.
+
+But the great advance which has been made rests on the discovery that
+bubonic plague is in the vast majority of cases transmitted by the flea.
+The pneumonic type forms a very small percentage of the human cases and
+even with it, the evidence indicates that the original infection is
+derived from a rodent through the intermediary of the insect.
+
+So modern prophylactic measures are directed primarily against the rat
+and fleas. Ships coming from infected ports are no longer disinfected
+for the purpose of killing the plague germs, but are fumigated to
+destroy the rats and the fleas which they might harbor. When anchored at
+infected ports, ships must observe strenuous precautions to prevent the
+ingress of rats. Cargo must be inspected just before being brought on
+board, in order to insure its freedom from rats. Even lines and hawsers
+must be protected by large metal discs or funnels, for rats readily run
+along a rope to reach the ship. Once infested, the ship must be
+thoroughly fumigated, not only to avoid carrying the disease to other
+ports but to obviate an outbreak on board.
+
+When an epidemic begins, rats must be destroyed by trapping and
+poisoning. Various so-called biological poisons have not proved
+practicable. Sources of food supply should be cut off by thorough
+cleaning up, by use of rat-proof garbage cans and similar measures. Hand
+in hand with these, must go the destruction of breeding places, and the
+rat-proofing of dwellings, stables, markets, warehouses, docks and
+sewers. All these measures are expensive, and a few years ago would have
+been thought wholly impossible to put into practice but now they are
+being enforced on a large scale in every fight against the disease.
+
+Rats and other rodents are regularly caught in the danger zone and
+examined for evidence of infection, for the sequence of the epizootic
+and of the human disease is now understood. In London, rats are
+regularly trapped and poisoned in the vicinity of the principal docks,
+to guard against the introduction of infected animals in shipping.
+During the past six years infected rats have been found yearly, thirteen
+having been found in 1912. In Seattle, Washington, seven infected rats
+were found along the water front in October, 1913, and infected ground
+squirrels are still being found in connection with the anti-plague
+measures in California.
+
+The procedure during an outbreak of the human plague was well
+illustrated by the fight in San Francisco. The city was districted, and
+captured rats, after being dipped in some fluid to destroy the fleas,
+were carefully tagged to indicate their source, and were sent to the
+laboratory for examination. If an infected rat was found, the officers
+in charge of the work in the district involved were immediately notified
+by telephone, and the infected building was subjected to a thorough
+fumigation. In addition, special attention was given to all the
+territory in the four contiguous blocks.
+
+By measures such as these, this dread scourge of the human race is being
+brought under control. Incidentally, the enormous losses due to the
+direct ravages of rats are being obviated and this alone would justify
+the expenditure many times over of the money and labor involved in the
+anti-rat measures.
+
+
+
+
+CHAPTER VII
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC ORGANISMS
+
+
+We now have to consider the cases in which the arthropod acts as the
+essential host of a pathogenic organism. In other words, cases in which
+the organism, instead of being passively carried or merely accidentally
+inoculated by the bite of its carrier, or vector, is taken up and
+undergoes an essential part of its development within the arthropod.
+
+[Illustration: 113. Dipylidium caninum. The double pored tapeworm of the
+dog.]
+
+In some cases, the sexual cycle of the parasite is undergone in the
+arthropod, which then serves as the _definitive_ or _primary host_. In
+other cases, it is the asexual stage of the parasite which is undergone,
+and the arthropod then acts as the _intermediate host_. This distinction
+is often overlooked and all the cases incorrectly referred to as those
+in which the insect or other arthropod acts as intermediate host.
+
+We have already emphasized that this is the most important way in which
+insects may transmit disease, for without them the particular organisms
+concerned could never complete their development. Exterminate the
+arthropod host and the life cycle of the parasite is broken, the disease
+is exterminated.
+
+As the phenomenon of alternation of generations, as exhibited by many of
+the parasitic protozoa, is a complicated one and usually new to the
+student, we shall first take up some of the grosser cases illustrated by
+certain parasitic worms. There is the additional reason that these were
+the first cases known of arthropod transmission of pathogenic organisms.
+
+
+INSECTS AS INTERMEDIATE HOSTS OF TAPEWORMS
+
+A number of tapeworms are known to undergo their sexual stage in an
+insect or other arthropod. Of these at least two are occasional
+parasites of man.
+
+_Dipylidium caninum_ (figs. 113 and 114), more generally known as
+_Taenia cucumerina_ or _T. elliptica_, is the commonest intestinal
+parasite of pet dogs and cats. It is occasionally found as a human
+parasite, 70 per cent of the cases reported being in young children.
+
+In 1869, Melnikoff found in a dog louse, _Trichodectes canis_, some
+peculiar bodies which Leuckart identified as the larval form of this
+tapeworm. The worm is, however, much more common in dogs and cats than
+is the skin parasite, and hence it appears that the _Trichodectes_ could
+not be the only intermediate host. In 1888, Grassi found that it could
+also develop in the cat and dog fleas, _Ctenocephalus felis_ and _C.
+canis_, and in the human flea, _Pulex irritans_.
+
+[Illustration: 114. Dipylidium caninum. Rostrum evaginated and
+invaginated. After Blanchard.]
+
+[Illustration: 115. Dipylidium caninum. Immature cysticercoid. After
+Grassi and Rovelli.]
+
+The eggs, scattered among the hairs of the dog or cat, are ingested by
+the insect host and in its body cavity they develop into pyriform
+bodies, about 300u in length, almost entirely destitute of a bladder,
+but in the immature stage provided with a caudal appendage (fig. 115).
+Within the pear-shaped body (fig. 116) are the invaginated head and
+suckers of the future tapeworm. This larval form is known as a
+cysticercoid, in contradistinction to the bladder-like cysticercus of
+many other cestodes. It is often referred to in literature as
+_Cryptocystis trichodectis_ Villot.
+
+As many as fifty of the cysticercoids have been found in the body cavity
+of a single flea. When the dog takes up an infested flea or louse, by
+biting itself, or when the cat licks them up, the larvae quickly develop
+into tapeworms, reaching sexual maturity in about twenty days in the
+intestine of their host. Puppies and kittens are quickly infested when
+suckling a flea-infested mother, the developing worms having been found
+in the intestines of puppies not more than five or six days old.
+
+[Illustration: 116. Dipylidium caninum. Cysticercoid. After Villet.]
+
+Infestation of human beings occurs only through accidental ingestion of
+an infested flea. It is natural that such cases should occur largely in
+children, where they may come about in some such way as illustrated in
+the accompanying figures 117 and 118.
+
+_Hymenolepis diminuta_, very commonly living in the intestine of mice
+and rats, is also known to occur in man. Its cysticercoid develops in
+the body cavity of a surprising range of meal-infesting insects. Grassi
+and Rovelli (abstract in Ransom, 1904) found it in the larvae and adult
+of a moth, _Asopia farinalis_, in the earwig, _Anisolabis annulipes_,
+the Tenebrionid beetles _Akis spinosa_ and _Scaurus striatus_. Grassi
+considers that the lepidopter is the normal intermediate host. The
+insect takes up the eggs scattered by rats and mice. It has been
+experimentally demonstrated that man may develop the tapeworm by
+swallowing infested insects. Natural infection probably occurs by
+ingesting such insects with cereals, or imperfectly cooked foods.
+
+[Illustration: 117. One way in which Dipylidium infection in children
+may occur. After Blanchard.]
+
+_Hymenolepis lanceolata_, a parasite of geese and ducks, has been
+reported once for man. The supposed cysticercoid occurs in various small
+crustaceans of the family Cyclopidae.
+
+[Illustration: 118. The probable method by which Dipylidium infection
+usually occurs.]
+
+Several other cestode parasites of domestic animals are believed to
+develop their intermediate stage in certain arthropods. Among these may
+be mentioned:
+
+_Choanotaenia infundibulformis_, of chickens, developing in the house-fly
+(Grassi and Rovelli);
+
+_Davainea cesticillus_, of chickens, in some lepidopter or coleopter
+(Grassi and Rovelli);
+
+_Hymenolepis anatina_, _H. gracilis_, _H. sinuosa_, _H. coronula_ and
+_Fimbriaria fasciolaris_, all occurring in ducks, have been reported as
+developing in small aquatic crustaceans. In these cases, cysticercoids
+have been found which, on account of superficial characters, have been
+regarded as belonging to the several species, but direct experimental
+evidence is scant.
+
+
+ARTHROPODS AS INTERMEDIATE HOSTS OF NEMATODE WORMS
+
+
+FILARIASIS AND MOSQUITOES--A number of species of Nematode worms
+belonging to the genus _Filaria_, infest man and other vertebrates and
+in the larval condition are to be found in the blood. Such infestation
+is known as _filariasis_. The sexually mature worms are to be found in
+the blood, the lymphatics, the mesentery and subcutaneous connective
+tissue. In the cases best studied it has been found that the larval
+forms are taken up by mosquitoes and undergo a transformation before
+they can attain maturity in man.
+
+The larvae circulating in the blood are conveniently designated as
+microfilariae. In this stage they are harmless and only one species,
+_Filaria bancrofti_, appears to be of any great pathological
+significance at any stage.
+
+_Filaria bancrofti_ in its adult state, lives in the lymphatics of man.
+Though often causing no injury it has been clearly established that they
+and their eggs may cause various disorders due to stoppage of the
+lymphatic trunks (fig. 119). Manson lists among other effects, abscess,
+varicose groin glands, lymph scrotum, chyluria, and elephantiasis.
+
+The geographical distribution of this parasite is usually given as
+coextensive with that of elephantiasis, but it is by no means certain
+that it is the only cause of this disease and so actual findings of the
+parasites are necessary. Manson reports that it is "an indigenous
+parasite in almost every country throughout the tropical and subtropical
+world, as far north as Spain in Europe and Charlestown in the United
+States, and as far south as Brisbane in Australia." In some sections,
+fully 50 per cent of the natives are infested. Labredo (1910) found
+17.82 per cent infestation in Havana.
+
+[Illustration: 119. Elephantiasis in Man. From "New Sydenham Society's
+Atlas."]
+
+The larval forms of _Filaria bancrofti_ were first discovered in 1863,
+by Demarquay, in a case of chylous dropsy. They were subsequently noted
+under similar conditions, by several workers, and by Wucherer in the
+urine of twenty-eight cases of tropical chyluria, but in 1872 Lewis
+found that the blood of man was the normal habitat, and gave them the
+name _Filaria sanguinis hominis_. The adult worm was found in 1876 by
+Bancroft, and in 1877, Cobbold gave it the name _Filaria bancrofti_. It
+has since been found repeatedly in various parts of the lymphatic
+system, and its life-history has been the subject of detailed studies by
+Manson (1884), Bancroft (1899), Low (1900), Grassi and Noe (1900), Noe
+(1901) and Fulleborn (1910).
+
+The larvae as they exist in the circulating blood, exhibit a very active
+wriggling movement, without material progression. They may exist in
+enormous numbers, as many as five or six hundred swarming in a single
+drop of blood. This is the more surprising when we consider that they
+measure about 300u x 8u, that is, their width is equal to the diameter
+of the red blood corpuscle of their host and their length over
+thirty-seven times as great.
+
+Their organs are very immature and the structure obscure. When they have
+quieted down somewhat in a preparation it may be seen that at the head
+end there is a six-lipped and very delicate prepuce, enclosing a short
+"fang" which may be suddenly exserted and retracted. Completely
+enclosing the larva is a delicate sheath, which is considerably longer
+than the worm itself. To enter into further details of anatomy is beyond
+the scope of this discussion and readers interested are referred to the
+work of Manson and of Fulleborn.
+
+One of the most surprising features of the habits of these larvae is the
+periodicity which they exhibit in their occurrence in the peripheral
+blood. If a preparation be made during the day time there may be no
+evidence whatever of filarial infestation, whereas a preparation from
+the same patient taken late in the evening or during the night may be
+literally swarming with the parasites. Manson quotes Mackenzie as having
+brought out the further interesting fact that should a "filarial subject
+be made to sleep during the day and remain awake at night, the
+periodicity is reversed; that is to say, the parasites come into the
+blood during the day and disappear from it during the night." There have
+been numerous attempts to explain this peculiar phenomenon of
+periodicity but in spite of objections which have been raised, the most
+plausible remains that of Manson, who believes that it is an adaptation
+correlated with the life-habits of the liberating agent of the parasite,
+the mosquito.
+
+The next stages in the development of _Filaria nocturna_ occur in
+mosquitoes, a fact suggested almost simultaneously by Bancroft and
+Manson in 1877, and first demonstrated by the latter very soon
+thereafter. The experiments were first carried out with _Culex
+quinquefasciatus_ (= _fatigans_) as a host, but it is now known that a
+number of species of mosquitoes, both anopheline and culicine, may serve
+equally well.
+
+When the blood of an infested individual is sucked up and reaches the
+stomach of such a mosquito, the larvae, by very active movements, escape
+from their sheaths and within a very few hours actively migrate to the
+body cavity of their new host and settle down primarily in the thoracic
+muscles. There in the course of sixteen to twenty days they undergo a
+metamorphosis of which the more conspicuous features are the formation
+of a mouth, an alimentary canal and a trilobed tail. At the same time
+there is an enormous increase in size, the larvae which measured .3 mm.
+in the blood becoming 1.5 mm. in length. This developmental period may
+be somewhat shortened in some cases and on the other hand may be
+considerably extended. The controlling factor seems to be the one of
+temperature.
+
+The transformed larvae then reenter the body cavity and finally the
+majority of them reach the interior of the labium (fig. 120). A few
+enter the legs and antennae, and the abdomen, but these are wanderers
+which, it is possible, may likewise ultimately reach the labium, where
+they await the opportunity to enter their human host.
+
+It was formerly supposed that when the infested mosquito punctured the
+skin of man, the mature larvae were injected into the circulation. The
+manner in which this occurred was not obvious, for when the insect feeds
+it inserts only the stylets, the labium itself remaining on the surface
+of the skin. Fulleborn has cleared up the question by showing that at
+this time the filariae escape and, like the hookworm, actively bore into
+the skin of their new host.
+
+[Illustration: 120. Filaria in the muscles and labium of Culex. After
+Blanchard.]
+
+Once entered, they migrate to the lymphatics and there quickly become
+sexually mature. The full grown females measure 85-90 mm. in length by
+.24-.28 mm. in diameter, while the males are less than half this size,
+being about 40 mm. by .1 mm. Fecundation occurs and the females will be
+found filled with eggs in various stages of development, for they are
+normally viviparous.
+
+_Filaria philippinensis_ is reported by Ashburn and Craig (1907) as a
+common blood filaria in the Philippine Islands. As they describe it, it
+differs from _Filaria bancrofti_ primarily in that it does not exhibit
+periodicity. Its development has been found to occur in _Culex
+quinquefasciatus_, where it undergoes metamorphosis in about fourteen or
+fifteen days. There is doubt as to the species being distinct from
+_bancrofti_.
+
+Several other species occur in man and are thought to be transferred by
+various insects, among which have been mentioned Tabanidae and
+tsetse-flies, but there is no experimental proof in support of such
+conjectures.
+
+_Filaria immitis_ is a dangerous parasite of the dog, the adult worm
+living in the heart and veins of this animal. It is one of the species
+which has been clearly shown to undergo its development in the mosquito,
+particularly in _Anopheles maculipennis_ and _Aedes calopus_ (=
+Stegomyia). The larval form occurs in the peripheral blood, especially
+at night. When taken up by mosquitoes they differ from _Filaria
+bancrofti_ in that they undergo their development in the Malpighian
+tubules rather than in the thoracic muscles. In about twelve days they
+have completed their growth in the tubules, pierce the distal end, and
+pass to the labium. This species occurs primarily in China and Japan,
+but is also found in Europe and in the United States. It is an
+especially favorable species for studying the transformations in the
+mosquito.
+
+[Illustration: 121. Dracunculus medinensis; female; mouth; embryo. After
+Bastian and Leuckart.]
+
+_Filariae_ are also commonly found in birds, and in this country this is
+the most available source of laboratory material. We have found them
+locally (Ithaca, N. Y.) in the blood of over sixty per cent of all the
+crows examined, at any season of the year, and have also found them in
+English sparrows.
+
+In the crows, they often occur in enormous numbers, as many as two
+thousand having been found in a single drop of the blood of the most
+heavily infested specimen examined. For study, a small drop of blood
+should be mounted on a clean slide and the coverglass rung with vaseline
+or oil to prevent evaporation. In this way they can be kept for hours.
+
+Permanent preparations may be made by spreading out the blood in a film
+on a perfectly clean slide and staining. This is easiest done by
+touching the fresh drop of blood with the end of a second slide which is
+then held at an angle of about 45^o to the first slide and drawn over it
+without pressure. Allow the smear to dry in the air and stain in the
+usual way with haematoxylin.
+
+
+OTHER NEMATODE PARASITES OF MAN AND ANIMALS DEVELOPING IN ARTHROPODS
+
+_Dracunculus medinensis_ (fig. 121), the so-called guinea-worm, is a
+nematode parasite of man which is widely distributed in tropical Africa,
+Asia, certain parts of Brazil and is occasionally imported into North
+America.
+
+The female worm is excessively long and slender, measuring nearly three
+feet in length and not more than one-fifteenth of an inch in diameter.
+It is found in the subcutaneous connective tissue and when mature
+usually migrates to some part of the leg. Here it pierces the skin and
+there is formed a small superficial ulcer through which the larvae reach
+the exterior after bursting the body of the mother.
+
+[Illustration: 122. Cyclops, the intermediate host of Dracunculus.]
+
+Fedtschenko (1879) found that when these larvae reach the water they
+penetrate the carapace of the little crustacean, _Cyclops_ (fig. 122).
+Here they molt several times and undergo a metamorphosis. Fedtschenko,
+in Turkestan, found that these stages required about five weeks, while
+Manson who confirmed these general results, found that eight or nine
+weeks were required in the cooler climate of England.
+
+Infection of the vertebrate host probably occurs through swallowing
+infested cyclops in drinking water. Fedtschenko was unable to
+demonstrate this experimentally and objection has been raised against
+the theory, but Leiper (1907), and Strassen (1907) succeeded in
+infesting monkeys by feeding them on cyclops containing the larvae.
+
+_Habronema muscae_ is a worm which has long been known in its larval
+stage, as a parasite of the house-fly. Carter found them in 33 per cent
+of the house-flies examined in Bombay during July, 1860, and since that
+time they have been shown to be very widely distributed. Italian workers
+reported them in 12 per cent to 30 per cent of the flies examined.
+Hewitt reported finding it rarely in England. In this country it was
+first reported by Leidy who found it in about 20 per cent of the flies
+examined at Philadelphia, Pa. Since then it has been reported by several
+American workers. We have found it at Ithaca, N. Y., but have not made
+sufficient examinations to justify stating percentage. Ransom (1913)
+reports it in thirty-nine out of one hundred and thirty-seven flies, or
+28 per cent.
+
+[Illustration: 123. An Echinorhynchid, showing the spinose retractile
+proboscis.]
+
+[Illustration: 124. June beetle (Lachnosterna).]
+
+[Illustration: Larva]
+
+Until very recently the life-history of this parasite was unknown but
+the thorough work of Ransom (1911, 1913) has shown clearly that the
+adult stage occurs in the stomach of horses. The embryos, produced by
+the parent worms in the stomach of the horse, pass out with the feces
+and enter the bodies of fly larvae which are developing in the manure. In
+these they reach their final stage of larval development at about the
+time the adult flies emerge from the pupal stage. In the adult fly they
+are commonly found in the head, frequently in the proboscis, but they
+occur also in the thorax and abdomen. Infested flies are accidentally
+swallowed by horses and the parasite completes its development to
+maturity in the stomach of its definitive host.
+
+_Gigantorhynchus hirudinaceus_ (= _Echinorhynchus gigas_) is a common
+parasite of the pig and has been reported as occurring in man. The adult
+female is 20-35 cm. long and 4-9 mm. in diameter. It lacks an alimentary
+canal and is provided with a strongly spined protractile rostrum, by
+means of which it attaches to the intestinal mucosa of its host.
+
+The eggs are scattered with the feces of the host and are taken up by
+certain beetle larvae. In Europe the usual intermediate hosts are the
+larvae of the cockchafer, _Melolontha vulgaris_, or of the flower beetle,
+_Cetonia aurata_. Stiles has shown that in the United States the
+intermediate host is the larva of the June bug, _Lachnosterna_ (fig.
+124). It is probable that several of the native species serve in this
+capacity.
+
+A number of other nematode parasites of birds and mammals have been
+reported as developing in arthropods but here, as in the case of the
+cestodes, experimental proof is scant. The cases above cited are the
+better established and will serve as illustrations.
+
+
+
+
+CHAPTER VIII
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA
+
+
+MOSQUITOES AND MALARIA
+
+Under the name of malaria is included a group of morbid symptoms
+formerly supposed to be due to a miasm or bad air, but now known to be
+caused by protozoan parasites of the genus _Plasmodium_, which attack
+the red blood corpuscles. It occurs in paroxysms, each marked by a
+chill, followed by high fever and sweating. The fever is either
+intermittent or remittent.
+
+There are three principal types of the disease, due to different species
+of the parasite. They are:
+
+1. The benign-tertian, caused by _Plasmodium vivax_, which undergoes its
+schizogony or asexual cycle in the blood in forty-eight hours or even
+less. This type of the disease,--characterized by fever every two days,
+is the most wide-spread and common.
+
+2. The quartan fever is due to the presence of _Plasmodium malariae_,
+which has an asexual cycle of seventy-two hours, and therefore the fever
+recurs every three days. This type is more prevalent in temperate and
+sub-tropical regions, but appears to be rare everywhere.
+
+3. The sub-tertian "aestivo-autumnal," or "pernicious" fever is caused by
+_Plasmodium falciparum_. Schizogony usually occurs in the internal
+organs, particularly in the spleen, instead of in the peripheral
+circulation, as is the case of the tertian and quartan forms. The fever
+produced is of an irregular type and the period of schizogony has not
+been definitely determined. It is claimed by some that the variations
+are due to different species of malignant parasites.
+
+It is one of the most wide-spread of human diseases, occurring in almost
+all parts of the world, except in the polar regions and in waterless
+deserts. It is most prevalent in marshy regions.
+
+So commonplace is malaria that it causes little of the dread inspired by
+most of the epidemic diseases, and yet, as Ross says, it is perhaps the
+most important of human diseases. Figures regarding its ravages are
+astounding. Celli estimated that in Italy it caused an average annual
+mortality of fifteen thousand, representing about two million cases. In
+India alone, according to Ross (1910) "it has been officially estimated
+to cause a mean annual death-rate of five per thousand; that is, to kill
+every year, on the average, one million one hundred and thirty
+thousand." In the United States it is widespread and though being
+restricted as the country develops, it still causes enormous losses.
+During the year 1911, "in Alabama alone there were seventy thousand
+cases and seven hundred and seventy deaths." The weakening effects of
+the disease, the invasion of other diseases due to the attacks of
+malaria, are among the very serious results, but they cannot be
+estimated.
+
+Not only is there direct effect on man, but the disease has been one of
+the greatest factors in retarding the development of certain regions.
+Everywhere pioneers have had to face it, and the most fertile regions
+have, in many instances been those most fully dominated by it. Herrick
+(1903) has presented an interesting study of its effects on the
+development of the southern United States and has shown that some parts,
+which are among the most fertile in the world, are rendered practically
+uninhabitable by the ravages of malaria. Howard (1909) estimates that
+the annual money loss from the disease in the United States is not less
+than $100,000,000.
+
+It was formerly supposed that the disease was due to a miasm, to a
+noxious effluvia, or infectious matter rising in the air from swamps. In
+other words its cause was, as the name indicated "mal aria," and the
+deep seated fear of night air is based largely on the belief that this
+miasm was given off at night. Its production was thought to be favored
+by stirring of the soil, dredging operations and the like.
+
+The idea of some intimate connection between malaria and mosquitoes is
+not a new one. According to Manson, Lancisi noted that in some parts of
+Italy the peasants for centuries have believed that malaria is produced
+by the bite of mosquitoes. Celli states that one not rarely hears from
+such peasants the statement that "In such a place, there is much fever,
+because it is full of mosquitoes." Koch points out that in German East
+Africa the natives call malaria and the mosquito by the same name,
+_Mbu_. The opinion was not lacking support from medical men. Celli
+quotes passages from the writings of the Italian physician, Lancisi,
+which indicate that he favored the view in 1717.
+
+Dr. Josiah Nott is almost universally credited with having supported the
+theory, in 1848, but as we have already pointed out his work has been
+misinterpreted. The statements of Beauperthuy, (1853) were more
+explicit.
+
+The clearest early presentation of the circumstantial evidence in favor
+of the theory of mosquito transmission was that of A. F. A. King, an
+American physician, in 1883. He presented a series of epidemiological
+data and showed "how they may be explicable by the supposition that the
+mosquito is the real source of the disease, rather than the inhalation
+or cutaneous absorption of a marsh vapor." We may well give the space to
+summarizing his argument here for it has been so remarkably
+substantiated by subsequent work:
+
+1. Malaria, like mosquitoes, affects by preference low and moist
+localities, such as swamps, fens, jungles, marshes, etc.
+
+2. Malaria is hardly ever developed at a lower temperature than 60^o
+Fahr., and such a temperature is necessary for the development of the
+mosquito.
+
+3. Mosquitoes, like malaria, may both accumulate in and be obstructed by
+forests lying in the course of winds blowing from malarious localities.
+
+4. By atmospheric currents malaria and mosquitoes are alike capable of
+being transported for considerable distances.
+
+5. Malaria may be developed in previously healthy places by turning up
+the soil, as in making excavations for the foundation of houses, tracks
+for railroads, and beds for canals, because these operations afford
+breeding places for mosquitoes.
+
+6. In proportion as countries, previously malarious, are cleared up and
+thickly settled, periodical fevers disappear, because swamps and pools
+are drained so that the mosquito cannot readily find a place suitable to
+deposit her eggs.
+
+7. Malaria is most dangerous when the sun is down and the danger of
+exposure after sunset is greatly increased by the person exposed
+sleeping in the night air. Both facts are readily explicable by the
+mosquito malaria theory.
+
+8. In malarial districts the use of fire, both indoors and to those who
+sleep out, affords a comparative security against malaria, because of
+the destruction of mosquitoes.
+
+9. It is claimed that the air of cities in some way renders the poison
+innocuous, for, though a malarial disease may be raging outside, it does
+not penetrate far into the interior. We may easily conceive that
+mosquitoes, while invading cities during their nocturnal pilgrimages
+will be so far arrested by walls and houses, as well as attracted by
+lights in the suburbs, that many of them will in this way be prevented
+from penetrating "far into the interior."
+
+10. Malarial diseases and likewise mosquitoes are most prevalent toward
+the latter part of summer and in the autumn.
+
+11. Various writers have maintained that malaria is arrested by canvas
+curtains, gauze veils and mosquito nets and have recommended the rise of
+mosquito curtains, "through which malaria can seldom or never pass." It
+can hardly be conceived that these intercept marsh-air but they
+certainly do protect from mosquitoes.
+
+12. Malaria spares no age, but it affects infants much less frequently
+than adults, because young infants are usually carefully housed and
+protected from mosquito inoculation.
+
+Correlated with the miasmatic theory was the belief that some animal or
+vegetable organism which lived in marshes, produced malaria, and
+frequent searches were made for it. Salisbury (1862) thought this
+causative organism to be an alga, of the genus _Palmella_; others
+attributed it to certain fungi or bacteria.
+
+In 1880, the French physician, Laveran, working in Algeria, discovered
+an amoeboid organism in the blood of malarial patients and definitely
+established the parasitic nature of this disease. Pigmented granules had
+been noted by Meckel as long ago as 1847, in the spleen and blood of a
+patient who had died of malaria, and his observations had been
+repeatedly verified, but the granules had been regarded as degeneration
+products, and the fact that they occurred in the body of a foreign
+organism had been overlooked.
+
+Soon after the discovery of the parasites in the blood, Gerhardt (1884)
+succeeded in transferring the disease to healthy individuals by
+inoculation of malarious blood, and thus proved that it is a true
+infection. This was verified by numerous experimenters and it was found
+that inoculation with a very minute quantity of the diseased blood would
+not only produce malaria but the particular type of disease.
+
+Laveran traced out the life cycle of the malarial parasite as it occurs
+in man. The details as we now know them and as they are illustrated by
+the accompanying figure 125, are as follows:
+
+The infecting organism or _sporozoite_, is introduced into the
+circulation, penetrates a red blood corpuscle, and forms the amoeboid
+_schizont_. This lives at the expense of the corpuscle and as it
+develops there are deposited in its body scattered black or reddish
+black particles. These are generally called melanin granules, but are
+much better referred to as haemozoin, as they are not related to
+melanin. The haemozoin is the most conspicuous part of the parasite, a
+feature of advantage in diagnosing from unstained preparations.
+
+[Illustration: 125. Life cycle of the malaria parasite. Adapted from
+Leuckart's chart, by Miss Anna Stryke.]
+
+As the schizont matures, its nucleus breaks up into a number of daughter
+nuclei, each with a rounded mass of protoplasm about it, and finally the
+corpuscles are broken down and these rounded bodies are liberated in the
+plasma as _merozoites_. These merozoites infect new corpuscles and thus
+the asexual cycle is continued. The malarial paroxysm is coincident with
+sporulation.
+
+As early as Laveran's time it was known that under conditions not yet
+determined there are to be found in the blood of malarious patients
+another phase of the parasite, differing in form according to the type
+of the disease. In the pernicious type these appear as large,
+crescent-shaped organisms which have commonly been called "crescents."
+We now know that these are sexual forms.
+
+When the parasite became known there immediately arose speculations as
+to the way in which it was transferred from man to man. It was thought
+by some that in nature it occurred as a free-living amoeba, and that
+it gained access to man through being taken up with impure water.
+However, numerous attempts to infect healthy persons by having them
+drink or inhale marsh water, or by injecting it into their circulation
+resulted in failure, and influenced by Leuckart's and Melnikoff's work
+on _Dipylidium_, that of Fedtschenko on _Dracunculus_, and more
+especially by that of Manson on _Filaria_, search was made for some
+insect which might transfer the parasite.
+
+Laveran had early suggested that the role of carrier might be played by
+the mosquito, but Manson first clearly formulated the hypothesis, and it
+was largely due to his suggestions that Ross in India, undertook to
+solve the problem. With no knowledge of the form or of the appearance in
+this stage, or of the species of mosquito concerned, Ross spent almost
+two and a half years of the most arduous work in the search and finally
+in August, 1897, seventeen years after the discovery of the parasite in
+man, he obtained his first definite clue. In dissecting a
+"dappled-winged mosquito," "every cell was searched and to my intense
+disappointment nothing whatever was found, until I came to the insect's
+stomach. Here, however, just as I was about to abandon the examination,
+I saw a very delicate circular cell, apparently lying amongst the
+ordinary cells of the organ and scarcely distinguishable from them. On
+looking further, another and another similar object presented itself. I
+now focused the lens carefully on one of these, and found that it
+contained a few minute granules of some black substance, exactly like
+the pigment of the parasite of malaria. I counted altogether twelve of
+these cells in the insect."
+
+Further search showed that "the contents of the mature pigment cells did
+not consist of clear fluid but of a multitude of delicate, thread-like
+bodies which on the rupture of the parent cell, were poured into the
+body cavity of the insect. They were evidently spores."
+
+With these facts established, confirmation and extension of Ross's
+results quickly followed, from many different sources. We cannot trace
+this work in detail but will only point out that much of the credit is
+due to the Italian workers, Grassi, Bignami, and Bastianelli, and to
+Koch and Daniels.
+
+It had already been found that when fresh blood was mounted and properly
+protected against evaporation, a peculiar change occurred in these
+crescents after about half an hour's time. From certain of them there
+were pushed out long whip-like processes which moved with a very active,
+lashing movement. The parasite at this stage is known as the
+"flagellated body." Others, differing somewhat in details of structure,
+become rounded but do not give off "flagella."
+
+The American worker, MacCallum (1897), in studying bird malaria as found
+in crows, first recognized the true nature of these bodies. He regarded
+them as sexual forms and believed that the so-called flagella played the
+part of spermatozoa. Thus, the "flagellated body" is in reality a
+_microgametoblast_, producing _microgametes_, or the male sexual
+element, while the others constitute the _macrogametes_, or female
+elements.
+
+It was found that when blood containing these sexual forms was sucked up
+by an Anopheline mosquito and taken into its stomach, a microgamete
+penetrated and fertilized a macrogamete in a way analogous to what takes
+place in the fertilization of the egg in higher forms. The resultant,
+mobile organism is known as the _migratory ookinete_. In this stage the
+parasite bores through the epithelial lining of the "stomach"
+(mid-intestine) of the mosquito and becomes encysted under the muscle
+layers. Here the _oocyst_, as it is now known, matures and breaks up
+into the body cavity and finally its products come to lie in the
+salivary glands of the mosquito. Ten to twelve days are required for
+these changes, after which the mosquito is infective, capable of
+introducing the parasite with its saliva, when feeding upon a healthy
+person.
+
+Thus the malarial parasite is known to have a double cycle, an
+alternation of generations, of which the asexual stage is undergone in
+man, the sexual in certain species of mosquitoes. The mosquito is
+therefore the definitive host rather than the _intermediate_, as usually
+stated.
+
+The complicated cycle may be made clearer by the diagram of Miss Stryke
+(1912) which, by means of a double-headed mosquito (fig. 126) endeavors
+to show how infection takes place through the biting of the human
+victim, (at A), in whom asexual multiplication then takes place, and how
+the sexual stages, taken up at B in the diagram, are passed in the body
+of the mosquito.
+
+[Illustration: 126. Life cycle of the malarial parasite. After Miss Anna
+Stryke.]
+
+The experimental proof that mosquitoes of the Anopheline group are
+necessary agents in the transmission of malaria was afforded in 1900
+when two English physicians, Drs. Sambon and Low lived for the three
+most malarial months in the midst of the Roman Campagna, a region
+famous for centuries as a hot-bed of malaria. The two experimenters
+moved about freely throughout the day, exposed themselves to rains and
+all kinds of weather, drank marsh water, slept exposed to the marsh air,
+and, in short, did everything which was supposed to cause malaria,
+except that they protected themselves thoroughly from mosquito bites,
+retiring at sunset to a mosquito-proof hut. Though they took no quinine
+and all of their neighbors suffered from malaria, they were absolutely
+free from the disease.
+
+To complete the proof, mosquitoes which had fed in Rome on malarious
+patients were sent to England and allowed to bite two volunteers, one of
+them Dr. Manson's own son, who had not been otherwise exposed to the
+disease. Both of these gentlemen contracted typical cases of malaria and
+the parasites were to be found in abundance in their blood.
+
+[Illustration: 127. Eggs of Anopheles. After Howard.]
+
+Since that time there have been many practical demonstrations of the
+fact that malaria is transmitted exclusively by the bite of mosquitoes
+and that the destruction of the mosquitoes means the elimination of the
+disease.
+
+We have said that the malarial parasite is able to undergo its
+development only in certain species of mosquitoes belonging to the
+Anopheline group. It is by no means certain that all of this group even,
+are capable of acting as the definitive host of the parasites, and much
+careful experiment work is still needed along this line. In the United
+States, several species have been found to be implicated, _Anopheles
+quadrimaculatus_ and _Anopheles crucians_ being the most common. The
+characteristics of these species and the distinctions between them and
+other mosquitoes will be discussed in Chapter XII.
+
+In antimalarial work it is desirable to distinguish the anopheline
+mosquitoes from the culicine species in all stages. The following
+tabulation presents the more striking distinctions between the groups as
+represented in the United States.
+
+_Anopheles_                             _Culex, Aedes, etc_.
+
+_Eggs_: Laid singly in small            Deposited in clumps in the
+numbers upon the surface of the         form of a raft (Culex group) or
+water. Eggs lie upon their sides        deposited singly in the water or
+and float by means of lateral           on the ground in places which
+expansions (fig. 127).                  may later be submerged.
+
+_Larva_: When at rest floats in         When at rest (with few exceptions)
+a horizontal position beneath the       floats suspended in an
+surface film. No respiratory            oblique or vertical position, or
+tube but instead a flattened            more rarely nearly horizontal,
+area on the eighth abdominal            with the respiratory tube in
+segment into which the two              contact with the surface film
+spiracles open (fig. 128).              (fig. 128).
+
+_Adults_: Palpi in both sexes           Palpi short in the female, in
+nearly or quite as long as the          the male usually elongate.
+proboscis. Proboscis projecting         Proboscis projects forward at an
+forward nearly on line with the         angle with the axis of the body.
+axis of the body. When at rest          When at rest on a vertical wall
+on a vertical wall the body is          the body is usually held parallel
+usually held at an angle with the       or the tip of the abdomen inclined
+vertical (fig. 128). Wings frequently   towards the wall (fig. 128).
+spotted (fig. 130).                     Wings usually not spotted.
+
+[Illustration: 128. (_a_) Normal position of the larvae of Culex and
+Anopheles in the water. Culex, left; Anopheles, middle; Culex pupa,
+right hand figure.]
+
+These malarial-bearing species are essentially domesticated mosquitoes.
+They develop in any accumulation of water which stands for a week or
+more. Ponds, puddles, rain barrels, horse troughs, cess-pools, cans,
+even the foot-prints of animals in marshy ground may afford them
+breeding places.
+
+[Illustration: 128. (_b_) Normal position of Culex and Anopheles on the
+wall.]
+
+It is clear from what has been said regarding the life cycle of the
+malarial parasite that the mosquito is harmless if not itself diseased.
+Hence malarial-bearing species may abound in the neighborhood where
+there is no malaria, the disease being absent simply because the
+mosquitoes are uninfected. Such a locality is potentially malarious and
+needs only the introduction of a malarial patient who is exposed to the
+mosquitoes. It is found that such patients may harbor the parasites in
+their blood long after they are apparently well and thus may serve as a
+menace, just as do the so-called typhoid carriers. In some malarious
+regions as high as 80-90 per cent of the natives are such
+malaria-carriers and must be reckoned with in antimalaria measures.
+
+Based upon our present day knowledge of the life cycle of the malarial
+parasite the fight against the disease becomes primarily a problem in
+economic entomology,--it is a question of insect control, in its
+broadest interpretation.
+
+[Illustration: 129. Larva of Anopheles. After Howard.]
+
+The lines of defence and offence against the disease as outlined by
+Boyce (1909) are:
+
+  1. Measures to avoid the reservoir (man):
+
+    Segregation.
+
+    Screening of patients.
+
+  2. Measures to avoid Anopheles:
+
+    Choice of suitable locality, when possible.
+
+    Screening of houses and porches.
+
+    Sleeping under mosquito nets.
+
+  3. Measures to exterminate the Anopheles:
+
+    Use of natural enemies.
+
+    Use of culicides, oiling ponds, etc.
+
+    Drainage and scavenging to destroy breeding places.
+
+    Enforcement of penalties for harboring larvae or keeping stagnant
+      water.
+
+    Educational methods.
+
+  4. Systematic treatment with quinine to exterminate the parasites.
+
+
+MOSQUITOES AND YELLOW FEVER
+
+Yellow fever was until recently one of the most dreaded of epidemic
+diseases. It is an acute, specific and infectious disease,
+non-contagious in character but occurring in epidemics, or endemics,
+within a peculiarly limited geographical area. It is highly fatal, but
+those who recover are generally immune from subsequent attacks.
+
+It is generally regarded as an American disease, having been found by
+Cortez, in Mexico, and being confined principally to the American
+continents and islands. It also occurs in Africa and attempts have been
+made to show that it was originally an African disease but there is not
+sufficient evidence to establish this view.
+
+There have been many noted outbreaks in the United States. Boston
+suffered from it in 1691 and again in 1693; New York in 1668 and as late
+as 1856; Baltimore in 1819. In 1793 occurred the great epidemic in
+Philadelphia, with a death rate of one in ten of the population. In the
+past century it was present almost every year in some locality of our
+Southern States, New Orleans being the greatest sufferer. In the latter
+city there were 7848 deaths from the disease in 1853, 4854 in 1858, and
+4046 in 1878. The last notable outbreak was in 1905. Reed and Carroll
+(1901) estimated that during the period from 1793 to 1900 there had not
+been less than 500,000 cases in the United States.
+
+[Illustration: 130. Anopheles quadrimaculatus, male and female,
+(x3-1/2). After Howard.]
+
+As in the case of the plague, the most stringent methods of control
+proved ineffective and helplessness, almost hopelessness marked the
+great epidemics. A vivid picture of conditions is that given by Mathew
+Cary, 1793 (quoted by Kelly, 1906) in "A Short Account of the Malignant
+Fever Lately Prevalent in Philadelphia."
+
+[Illustration: 131. Anopheles punctipennis. Female, (x4). After Howard.]
+
+"The consternation of the people of Philadelphia at this period was
+carried beyond all bounds. Dismay and affright were visible in the
+countenance of almost every person. Of those who remained, many shut
+themselves in their houses and were afraid to walk the streets. * * *
+The corpses of the most respectable citizens, even those who did not die
+of the epidemic, were carried to the grave on the shafts of a chair
+(chaise), the horse driven by a negro, unattended by friends or
+relative, and without any sort of ceremony. People hastily shifted their
+course at the sight of a hearse coming toward them. Many never walked on
+the footpath, but went into the middle of the streets to avoid being
+infected by passing by houses wherein people had died. Acquaintances and
+friends avoided each other in the streets and only signified their
+regard by a cold nod. The old custom of shaking hands fell into such
+disuse that many shrunk back with affright at even the offer of the
+hand. A person with a crape, or any appearance of mourning was shunned
+like a viper. And many valued themselves highly on the skill and address
+with which they got to the windward of every person they met. Indeed, it
+is not probable that London, at the last stage of the plague, exhibited
+stronger marks of terror than were to be seen in Philadelphia from the
+24th or 25th of August until pretty late in September."
+
+[Illustration: 132. Anopheles crucians. Female (x4). After Howard.]
+
+Such was the condition in Philadelphia in 1793 and, as far as methods of
+control of the disease were concerned, there was practically no advance
+during the last century. The dominant theory was that yellow fever was
+spread by _fomites_, that is, exposed bedding, clothing, baggage, and
+the like. As late as 1898 a bulletin of the United States Marine
+Hospital Service stated:
+
+"While yellow fever is a communicable disease, it is not contagious in
+the ordinary acceptance of the term, but is spread by the infection of
+places and articles of bedding, clothing, and furniture."
+
+Based upon this theory, houses, baggage, freight, even mail, were
+disinfected, and the most rigid quarantine regulations were enforced.
+The hardships to which people of the stricken regions were subjected and
+the financial losses are incalculable. And withal, the only efficient
+check upon the disease seemed to be the heavy frosts. It was found that
+for some reason, the epidemic abated with cold weather,--a measure
+beyond human control.
+
+[Illustration: 133. Culex sollicitans. Female (x4). After Howard.]
+
+It is not strange that among the multitude of theories advanced to
+explain the cause and method of dissemination of the disease there
+should be suggestions that yellow fever was transmitted by the mosquito.
+We have seen that Beauperthuy (1855) clearly urged this theory.
+
+More detailed, and of the greatest influence in the final solution of
+the problem were the arguments of Dr. Carlos Finlay, of Havana. In 1881,
+in a paper presented before the "Real Academia de Ciencias Medicas,
+Fisicas y Naturales de la Habana," he said:
+
+"I feel convinced that any theory which attributes the origin and the
+propagation of yellow fever to atmospheric influences, to miasmatic or
+meteorological conditions, to filth, or to the neglect of general
+hygienic precautions, must be considered as utterly indefensible."
+
+He postulated the existence of a material transportable substance
+causing yellow fever,--"something tangible which requires to be conveyed
+from the sick to the healthy before the disease can be propagated" and
+after discussing the peculiarities of the spread of the disease and the
+influence of meteorological conditions, he decides that the carriers of
+the disease must be sought among insects. He continues:
+
+"On the other hand, the fact of yellow fever being characterized both
+clinically and (according to recent findings) histologically, by lesions
+of the blood vessels and by alterations of the physical and chemical
+conditions of the blood, suggested that the insect which should convey
+the infectious particles from the patient to the healthy should be
+looked for among those which drive their sting into blood vessels in
+order to suck human blood. Finally, by reason of other considerations
+which need not be stated here, I came to think that the mosquito might
+be the transmitter of yellow fever."
+
+"Assimilating the disease to small-pox and to vaccination, it occurred
+to me that in order to inoculate yellow fever it would be necessary to
+pick out the inoculable material from within the blood vessels of a
+yellow fever patient and to carry it likewise into the interior of a
+blood vessel of a person who was to be inoculated. All of which
+conditions the mosquito satisfies most admirably through its bite."
+
+In the course of his study of the problem, Finlay made detailed studies
+of the life history and habits of the common mosquitoes at Havana, and
+arrived at the conclusion that the carrier of the yellow fever was the
+_Culex mosquito_ or _Aedes calopus_, as it is now known. With this
+species he undertook direct experimental tests, and believed that he
+succeeded in transmitting the disease by the bite of infected mosquitoes
+in three cases. Unfortunately, possibility of other exposure was not
+absolutely excluded, and the experiments attracted little attention.
+
+Throughout the next twenty years Finlay continued his work on yellow
+fever, modifying his original theory somewhat as time went on. Among his
+later suggestions was that in the light of Smith's work on Texas fever,
+his theory must be "somewhat modified so as to include the important
+circumstance that the faculty of transmitting the yellow fever germ need
+not be limited to the parent insect, directly contaminated by stinging a
+yellow fever patient (or perhaps by contact with or feeding from his
+discharges), but may be likewise inherited by the next generation of
+mosquitoes issued from the contaminated parent." He believed that the
+bite of a single mosquito produced a light attack of the disease and was
+thus effective in immunizing the patient. Throughout the period, many
+apparently successful attempts to transmit the disease by mosquitoes
+were made. In the light of present day knowledge we must regard these as
+defective not only because possibility of other infection was not
+absolutely excluded but because no account was taken of the incubation
+period within the body of the mosquito.
+
+In 1900, while the American army was stationed in Cuba there occurred an
+epidemic of yellow fever and an army medical board was appointed for
+"the purpose of pursuing scientific investigations with reference to the
+acute infectious diseases prevalent on the island." This was headed by
+Walter Reed and associated with him were James Carroll, Jesse W. Lazear
+and Aristides Agramonte, the latter a Cuban immune. For a detailed
+summary of this work the lay reader cannot do better than read Dr.
+Kelly's fascinating biography "Walter Reed and Yellow Fever."
+
+Arriving at the army barracks near Havana the Commission first took up
+the study of _Bacillus icteroides_, the organism which Sanarelli, an
+Italian physician, had declared the causative agent in yellow fever.
+They were unable to isolate this bacillus either from the blood during
+life or from the blood and organs of cadavers and therefore turned their
+attention to Finlay's theory of the propagation of yellow fever by means
+of the mosquito. In this work they had the unselfish and enthusiastic
+support of Dr. Finlay himself, who not only consulted with them and
+placed his publications at their disposal, but furnished eggs from which
+their experimental mosquitoes were obtained. Inoculations of eleven
+non-immunes through the bite of infected mosquitoes were made, and of
+these, two gave positive results. The first of the two was Dr. Carroll
+who allowed himself to be bitten by a mosquito which had been caused to
+feed upon four cases of yellow fever, two of them severe and two mild.
+The first patient had been bitten twelve days before.
+
+Three days after being bitten, Dr. Carroll came down with a typical case
+of yellow fever. So severe was the attack that for three days his life
+hung in the balance. During his convalescence an incident occurred which
+showed how the theory of mosquito transmission of the disease was
+generally regarded. We quote from Dr. Kelly: "One of his nurses who came
+from Tennessee had had considerable experience with yellow fever, having
+indeed, lost her husband and several children from it. One day early in
+his illness Dr. Carroll mentioned to her that he had contracted the
+disease through the bite of a mosquito, and noticed that she looked
+surprised. Some time later, when well enough to look over the daily
+records of his condition, he found this entry: 'Says he got his illness
+through the bite of a mosquito,--delirious'."
+
+The second case was that of an American who was bitten by four
+mosquitoes, two of which had bitten severe (fatal) cases of yellow fever
+twelve days previously, one of which had bitten a severe case (second
+day) sixteen days before and one which had bitten a severe case eight
+days before. Five days later, the subject developed a well pronounced
+but mild case of the disease.
+
+In the meantime, another member of the Commission, Dr. Lazear, was
+accidentally bitten by a mosquito while collecting blood from yellow
+fever patients. Five days later he contracted a typical case which
+resulted fatally.
+
+So clear was the evidence from these preliminary experiments that the
+commission felt warranted in announcing, October 27, 1900, that, "The
+mosquito serves as the intermediate host for the parasite of yellow
+fever, and it is highly probable that the disease is only propagated
+through the bite of this insect."
+
+In order to extend the experimental evidence under conditions which
+could leave no possibility of infection from other sources, a special
+experimental sanitary station, named in honor of the deceased member of
+the Commission, was established in an open field near the town of
+Quemados, Cuba. Here there were constructed two small buildings known
+respectively as the "infected clothing building" and the "infected
+mosquito building."
+
+The infected clothing building, 14 x 20 feet in size, was purposely so
+constructed as to exclude anything like efficient ventilation, but was
+thoroughly screened to prevent the entrance of mosquitoes. Into this
+building were brought sheets, pillow-slips, blankets, etc., contaminated
+by contact with cases of yellow fever and their discharges,--many of
+them purposely soiled with a liberal quantity of black vomit, urine, and
+fecal matter from patients sick with yellow fever. Nothing could better
+serve as the fomites which were supposed to convey the dread disease.
+
+Three non-immunes unpacked these articles, giving each a thorough
+handling and shaking in order to disseminate through the air of the room
+the specific agent of the disease. They were then used in making up the
+beds which the volunteers occupied each night for a period of twenty
+days. The experiment was repeated three times, volunteers even sleeping
+in the soiled garments of yellow fever victims but in not a single case
+was there the slightest symptom of disease. The theory of the spread of
+yellow fever by fomites was completely demolished.
+
+The infected mosquito building, equal in size to its companion, was the
+antithesis as far as other features were concerned. It was so
+constructed as to give the best possible ventilation, and bedding which
+was brought into it was thoroughly sterilized. Like the infected
+clothing building it was carefully screened, but in this case it was in
+order to keep mosquitoes in it as well as to prevent entrance of others.
+Through the middle of the room ran a mosquito-proof screen.
+
+On December 5, 1900, a non-immune volunteer who had been in the
+quarantine camp for fifteen days and had had no other possible exposure,
+allowed himself to be bitten by five mosquitoes which had fed on yellow
+fever patients fifteen or more days previously. The results were fully
+confirmatory of the earlier experiments of the Commission--at the end of
+three days, nine and a half hours, the subject came down with a well
+marked case of yellow fever.
+
+In all, ten cases of experimental yellow fever, caused by the bite of
+infected mosquitoes were developed in Camp Lazear. Throughout the period
+of the disease, other non-immunes slept in the little building,
+separated from the patient only by the mosquito-proof screen, but in no
+circumstances did they suffer any ill effects.
+
+It was found that a yellow fever patient was capable of infecting
+mosquitoes only during the first three or four days after coming down
+with the disease. Moreover, after the mosquito has bitten such a
+patient, a period of at least twelve days must elapse before the insect
+is capable of transmitting the disease.
+
+Once the organism has undergone its twelve day development, the mosquito
+may remain infective for weeks. In experiments of the Commission, two of
+the mosquitoes transmitted the disease to a volunteer fifty-seven days
+after their contamination. No other volunteers presenting themselves,
+one of these mosquitoes died the sixty-ninth and one the seventy-first
+day after their original contamination, without it being determined
+whether they were still capable of transmitting the disease.
+
+So carefully carried out was this work and so conclusive were the
+results that Dr. Reed was justified in writing:
+
+"Six months ago, when we landed on this island, absolutely nothing was
+known concerning the propagation and spread of yellow fever--it was all
+an unfathomable mystery--but today the curtain has been drawn--its mode
+of propagation is established and we know that a case minus mosquitoes
+is no more dangerous than one of chills and fever."
+
+The conclusions of the Commission were fully substantiated by numerous
+workers, notably Dr. Guiteras of the Havana Board of Health, who had
+taken a lively interest in the work and whose results were made known in
+1901, and by the Brazilian and French Commission at Sao Paulo, Brazil,
+in 1903.
+
+Throughout the work of the Army Commission and down to the present time
+many fruitless efforts have been made to discover the specific organism
+of yellow fever. It was clearly established that the claims of Sanarelli
+for _Bacillus icteroides_ were without foundation. It was found, too,
+that whatever the infective agent might be it was capable of passing
+through a Berkefeld filter and thus belongs to the puzzling group of
+"filterable viruses." It was further found that the virus was destroyed
+by heating up to 55^o C for ten minutes. It is generally believed that
+the organism is a Protozoan.
+
+The question of the hereditary transmission of the yellow fever organism
+within the mosquito was left unsettled by the Army Commission, though,
+as we have seen, it was raised by Finlay. Marchoux and Simond, of the
+French Commission devoted much attention to this phase of the problem
+and basing their conclusions on one apparently positive case, they
+decided that the disease could be transmitted through the egg of an
+infected _Aedes calopus_ to the second generation and thence to man. The
+conclusion, which is of very great importance in the control of yellow
+fever, has not been verified by other workers.
+
+Once clearly established that yellow fever was transmitted solely by
+mosquitoes, the question of the characteristics, habits, and
+geographical distribution of the insect carrier became of vital
+importance.
+
+_Aedes calopus_, more commonly known as _Stegomyia fasciata_ or
+_Stegomyia calopus_ (fig. 134) is a moderate sized, rather strikingly
+marked mosquito. The general color is dark-brown or reddish-brown, but
+the thorax has a conspicuous broad, silvery-white curved line on each
+side, with two parallel median silvery lines. Between the latter there
+is a slender, broken line. The whole gives a lyre-shaped pattern to the
+thorax. The abdomen is dark with silvery-white basal bands and silvery
+white spots on each side of the abdominal segments. Legs black with
+rings of pure white at the base of the segments.
+
+Size of the female 3.3 to 5 mm.; male 3 to 4.5 mm.
+
+[Illustration: 134. The yellow fever mosquito (Aedes calopus). (x7).
+After Howard.]
+
+It is preeminently a domesticated species, being found almost
+exclusively about the habitation of man. "Its long association with man
+is shown by many of its habits. It approaches stealthily from behind. It
+retreats upon the slightest alarm. The ankles and, when one is sitting
+at a table or desk, the underside of the hands and wrists are favorable
+points of attack. It attacks silently, whereas other mosquitoes have a
+piping or humming note. The warning sound has doubtless been suppressed
+in the evolutionary process of its adaptation to man. It is extremely
+wary. It hides whenever it can, concealing itself in garments, working
+into the pockets, and under the lapels of coats, and crawling up under
+the clothes to bite the legs. In houses, it will hide in dark corners,
+under picture moldings and behind the heads of old-fashioned bedsteads.
+It will enter closets and hide in the folds of garments."--Howard.
+
+It was claimed by the French Commission, and subsequently often stated
+in discussions of the relation of the mosquito to yellow fever that the
+mature _Aedes calopus_ will bite only at night. If this were true it
+would be of the greatest importance in measures to avoid the disease.
+Unfortunately, the claim was illy founded and numerous workers have
+clearly established that the exact converse is more nearly true, this
+mosquito being pre-eminently a day species, feeding most actively in
+early morning, about sunrise, and late in the afternoon. On cloudy days
+it attacks at any time during the day. Thus there is peril in the
+doctrine that infected regions may be visited with perfect safety during
+the daytime and that measures to avoid the mosquito attack need be taken
+only at night.
+
+[Illustration: 135_a_. Aedes calopus. Pupa. After Howard.]
+
+Dr. Finlay maintained that the adult, even when starved, would not bite
+when the temperature was below 23^o C, but subsequent studies have shown
+that this statement needs modification. The French Commission, working
+at Rio de Janeiro, found that _Aedes calopus_ would bite regularly at
+temperatures between 22^o and 25^o and that the optimum temperature was
+between 27^o and 30^o C, but their experiments led them to believe that it
+would bite in nature at a temperature as low as 17^o C.
+
+The yellow fever mosquito breeds in cisterns, water barrels, pitchers
+and in the various water receptacles about the house. In our own
+Southern States it very commonly breeds in the above-ground cisterns
+which are in general use. Often the larvae (fig. 135b) are found in
+flower vases, or even in the little cups of water which are placed under
+the legs of tables to prevent their being overrun by ants. They have
+been repeatedly found breeding in the holy water font in churches. In
+short, they breed in any collection of water in close proximity to the
+dwellings or gathering places of man.
+
+The life cycle under favorable conditions is completed in from twelve to
+fifteen days. These figures are of course very dependent upon the
+temperature. The Army Commission in Cuba found that the cycle might be
+completed in as brief a period as nine and a half days. Under less
+favorable conditions it may be greatly lengthened.
+
+The adults are long lived. We have seen that during the experimental
+work in Cuba specimens were kept in captivity for sixty-nine and
+seventy-one days, respectively, and that they were proved to retain
+their infectivity for at least fifty-seven days. Dr. Guiteras
+subsequently kept an infected adult for one hundred and fifty-four days.
+
+Low temperatures have a very great effect not only on development, but
+on the activity and even life of the adults. Long before the method of
+transmission of yellow fever was discovered it was well known that the
+epidemics were brought to a close by heavy frosts, and it is now known
+that this is due to the killing of the mosquitoes which alone could
+spread the disease.
+
+[Illustration: 135_b_. Aedes calopus; larva. (x7). After Howard.]
+
+_Aedes calopus_ has a very wide distribution since, as Howard says,
+being a domestic mosquito, having a fairly long life in the adult stage,
+and having the custom of hiding itself in the most ingenious ways, it is
+particularly subject to carriage for long distances on board vessels, in
+railway trains, even packed in baggage. In general, its permanent
+distribution is from 40 degrees north latitude to 40 degrees south
+latitude (Brumpt), in a belt extending around the world. In the United
+States it breeds in most of our Southern States.
+
+Thus, as in the case of malaria, there are many places where the insect
+carrier is abundant but where yellow fever does not occur. Such, for
+instance, are Hawaii, Australia and Asia. An outbreak may occur at any
+time that a patient suffering from the disease is allowed to enter and
+become a source of infection for the mosquitoes. In this connection
+various writers have called attention to the menace from the Panama
+Canal. When it is completed, it will allow of direct passage from
+regions where yellow fever is endemic and this will greatly increase the
+possibility of its introduction into these places where it is now
+unknown. The result, with a wholly non-immune population, would be
+appalling.
+
+On the other hand, there are places wholly outside of the normal range
+of _Aedes calopus_ where the disease has raged. Such are New York,
+Boston, and even Philadelphia, which have suffered notable epidemics.
+These outbreaks have been due to the introduction of infected mosquitoes
+during the heat of summer, when they have not only conveyed the disease
+but have found conditions favorable for their multiplication. Or,
+uninfected mosquitoes have been thus accidentally brought in and
+developed in large numbers, needing then only the accidental
+introduction of cases of the disease to start an epidemic.
+
+Methods of control of various diseases have been revolutionized by the
+discovery that they were insect-borne, but in no other case has the
+change been as radical or the results as spectacular as in the case of
+yellow fever. The "shot-gun quarantine," the sufferings and horrors, the
+hopelessness of fighting absolutely blindly have given way to an
+efficient, clear-cut method of control, based upon the knowledge that
+the disease is carried from man to man solely by the mosquito, _Aedes
+calopus_. The lines of defense and offense are essentially as follows:
+
+In the first place, when a case of yellow fever occurs, stringent
+precautions must be adopted to prevent the infection of mosquitoes and
+the escape of any already infected. This means that the patient must be
+removed to a mosquito-proof room, or ward beyond reach of the insects,
+and that the infected room must be thoroughly fumigated at once, to kill
+the mosquitoes hiding within it. All cracks and openings should be
+closed with strips of paper and fumigation with burning sulphur or
+pyrethrum carefully carried out.
+
+It should be remembered that if the first case noted is that of a
+resident rather than imported, it means that the mosquito carriers
+became infected more than two weeks before the case was diagnosed, for
+as we have seen, the germ must undergo a twelve-day period of
+development within its insect host. Therefore a careful search must be
+made for mild cases which, though unrecognized, may serve as foci for
+the spread of the disease.
+
+In face of a threatened epidemic one of the most essential measures is
+to educate the citizens and to gain their complete cooperation in the
+fight along modern lines. This may be done through the schools, the
+pulpit, places of amusement, newspapers and even bulletin boards.
+
+Emphasis should be placed on the necessity of both non-immunes and
+immunes using mosquito curtains, and in all possible ways avoiding
+exposure to the mosquitoes.
+
+Then the backbone of the fight must be the anti-mosquito measures. In
+general, these involve screening and fumigating against adults, and
+control of water supply, oiling, and drainage against the larvae. The
+region involved must be districted and a thorough survey undertaken to
+locate breeding places, which must, if possible, be eradicated. If they
+are necessary for water supplies, such as casks, or cisterns, they
+should be carefully screened to prevent access of egg-laying adults.
+
+The practical results of anti-mosquito measures in the fight against
+yellow fever are well illustrated by the classic examples of the work in
+Havana, immediately following the discoveries of the Army Commission and
+by the stamping out of the New Orleans epidemic in 1905.
+
+The opportunities for an immediate practical application of the theories
+of the Army Commission in Havana were ideal. The city had always been a
+hotbed of yellow fever and was the principal source from which the
+disease was introduced year after year into our Southern States. It was
+under martial law and with a military governor who was himself a
+physician and thoroughly in sympathy with the views of the Commission,
+the rigid enforcement of the necessary regulations was possible. The
+story of the first campaign has been often told, but nowhere more
+clearly than in Dr. Reed's own account, published in the _Journal of
+Hygiene_ for 1902.
+
+Closer home was the demonstration of the efficacy of these measures in
+controlling the yellow fever outbreak in New Orleans in 1905. During the
+spring and early summer of the year the disease had, unperceived, gained
+a firm foothold in that city and when, in early July the local Board of
+Health took cognizance of its existence, it was estimated that there had
+been in the neighborhood of one hundred cases.
+
+Conditions were not as favorable as they had been under martial law in
+Havana for carrying on a rigid fight along anti-mosquito lines. The
+densely populated city was unprepared, the public had to be educated,
+and an efficient organization built up. The local authorities actively
+began a general fight against the mosquito but in spite of their best
+efforts the disease continued to spread. It was recognized that more
+rigid organization was needed and on August 12th the United States
+Public Health and Marine Hospital Service was put in absolute charge of
+the fight. Up to this time there had been one hundred and forty-two
+deaths from a total of nine hundred and thirteen cases and all of the
+conditions seemed to threaten an outbreak to exceed the memorable one of
+1878 when, as we have seen there were four thousand and forty-six
+deaths.
+
+With the hearty cooperation of the citizens,--physicians and laymen
+alike,--the fight was waged and long before frost or any near approach
+thereto the disease was stamped out,--a thing unheard of in previous
+epidemics. The total loss of life was four hundred and sixty--about 11
+per cent as great as that from the comparable epidemic of 1878. If the
+disease had been promptly recognized and combated with the energy which
+marked the fight later in the summer, the outbreak would have made
+little headway and the great proportion of these lives would have been
+saved.
+
+
+
+
+CHAPTER IX
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA (Continued)
+
+
+INSECTS AND TRYPANOSOMIASES
+
+By trypanosomiasis is meant a condition of animal parasitism, common to
+man and the lower animals, in which trypanosomes, peculiar flagellate
+protozoa, infest the blood. Depending upon the species, they may be
+harmless, producing no appreciable ill-effect, or pathogenic, giving
+rise to conditions of disease. A number of these are known to be
+transferred by insects.
+
+In order that we may consider more fully the developmental stage of
+these parasites within their insect host, it is necessary that we
+describe briefly the structure of the blood-inhabiting stage.
+
+[Illustration: 136. Trypanosoma brucei. After Bruce.]
+
+The trypanosomes are elongated, usually pointed, flagellated protozoa
+(fig. 136) in which the single flagellum, bent under the body, forms the
+outer limit of a delicate undulating membrane. It arises near one end of
+the organism from a minute centrosome-like body which is known as the
+blepheroplast, and at the opposite end extends for a greater or less
+distance as a free flagellum. Enclosing, or close beside the
+blepheroplast is the small kinetonucleus. The principal nucleus, round
+or oval in form, is situated near the center of the body. Asexual
+reproductions occurs in this stage, by longitudinal fission, the nucleus
+and the blepheroplast dividing independently of one another. From the
+blepheroplast of one of the daughter cells a new flagellum is formed.
+
+Among the pathogenic species are to be found the causative organisms of
+some of the most serious diseases of domestic animals and even of man.
+It is probable that these pathogenic species secrete a specific poison.
+The majority of them are tropical in distribution.
+
+Though we are concerned especially with the species which infest man, we
+shall first consider two of the trypanosomes of lower animals, known
+long before any of those of man had been found.
+
+
+FLEAS AND LICE AS CARRIERS OF TRYPANOSOMA LEWISI.--_Trypanosoma lewisi_,
+the first mammalian trypanosome known, is to be found in the blood of
+wild rats. Like its host, it appears to be cosmopolitan in distribution,
+having been reported from several localities in the United States,
+Brazil, Argentine, England, Germany, France, Italy, Russia, Asia and
+Africa.
+
+This species is usually regarded as non-pathogenic, but in experimental
+work, especially with white rats, heavy infestations often result
+fatally, and naturally infested specimens sometimes show evidence of
+injury. Rats which have been infested exhibit at least temporary
+immunity against new infection.
+
+_Trypanosoma lewisi_ is transmitted from rat to rat by fleas and by
+lice. Rabinowitsch and Kempner (1899) first found that healthy rats
+which were kept with infested rats, showed trypanosomes in their blood
+after about two weeks. They found the trypanosomes in the alimentary
+canal of fleas which had fed on the diseased rats. On teasing such fleas
+in physiological salt solution and inoculating them into fresh rats they
+were able to produce the infection. Finally, they showed that the fleas
+which had fed upon infested rats were able to carry the parasites to
+healthy rats. Corresponding experiments with lice were not successful.
+Prowazek (1905) found in the rat louse (_Haematopinus spinulosus_)
+organisms which he regarded as developmental stages of the _Trypanosoma
+lewisi_. He believed that the sexual cycle was undergone in this insect.
+
+Nuttall (1908) readily transmitted the trypanosomes through the agency
+of fleas, (_Ceratophyllus fasciatus_ and _Ctenopthalmus agyrtes_). He
+believes that these insects are probably the chief transmitters of the
+parasite. He was also able to transmit it from diseased to healthy rats
+through the agency of the rat louse. He was unable to trace any
+developmental stages in the louse and inclined to the opinion that
+Prowazek was deceived by the presence of extraneous flagellates such as
+are known to exist in a number of blood-sucking arthropods.
+
+Nuttall concludes that since three distinct kinds of blood-sucking
+insects are capable of transmitting _Trypanosoma lewisi_ it appears
+doubtful that this flagellate is a parasite of the invertebrate "host"
+in the sense claimed by Prowazek and other investigators.
+
+
+TSETSE-FLIES AND NAGANA--One of the greatest factors in retarding the
+development of certain regions of Africa has been the presence of a
+small fly, little larger than the common house-fly. This is the
+tsetse-fly, _Glossina morsitans_ (fig. 165) renowned on account of the
+supposed virulence of its bite for cattle, horses and other domestic
+mammals.
+
+The technical characteristics of the tsetse-flies, or Glossinas, and
+their several species, will be found in a later chapter. We need
+emphasize only that they are blood-sucking Muscidae and that, unlike the
+mosquitoes, the sexes resemble each other closely in structure of the
+mouth-parts, and in feeding habits.
+
+In 1894, Colonel David Bruce discovered that the fly was not in itself
+poisonous but that the deadly effect of its bite was due to the fact
+that it transmitted a highly pathogenic blood parasite, _Trypanosoma
+brucei_. This trypanosome Bruce had discovered in the blood of South
+African cattle suffering from a highly fatal disease known as "nagana".
+On inoculating the blood of infected cattle into horses and dogs he
+produced the disease and found the blood teeming with the causative
+organism. In the course of his work he established beyond question that
+the "nagana" and the tsetse-fly disease were identical.
+
+Tsetse-flies of the species _Glossina morsitans_, which fed upon
+diseased animals, were found capable of giving rise to the disease in
+healthy animals up to forty-eight hours after feeding. Wild tsetse-flies
+taken from an infected region to a region where they did not normally
+occur were able to transmit the disease to healthy animals. It was found
+that many of the wild animals in the tsetse-fly regions harbored
+_Trypanosoma brucei_ in their blood, though they showed no evidence of
+disease. As in the case of natives of malarial districts, these animals
+acted as reservoirs of the parasite. Non-immune animals subjected to the
+attacks of the insect carrier, quickly succumbed to the disease.
+
+A question of prime importance is as to whether the insect serves as an
+essential host of the pathogenic protozoan or whether it is a mere
+mechanical carrier. Bruce inclined to the latter view. He was unable to
+find living trypanosomes in the intestines or excrements of the fly or
+to produce the disease on the many occasions when he injected the
+excrement into healthy animals. Moreover, he had found that the
+experimental flies were infective only during the first forty-eight
+hours and that if wild flies were taken from the infected region, "kept
+without food for three days and then fed on a healthy dog, they never
+gave rise to the disease."
+
+Koch had early described what he regarded as sexual forms from the
+intestine of the fly but it remained for Kleine (1909) to experimentally
+demonstrate that a part of the life cycle of the parasite was undergone
+in the fly. Working with _Glossina palpalis_, he found that for a period
+of ten days or longer after feeding on an animal suffering from nagana
+it was non-infective, but that then it became infective and was able to
+transmit the disease for weeks thereafter. He discovered and described
+developmental stages of the parasite within the intestine of the insect.
+In other words, the tsetse-fly (in nature, _Glossina morsitans_), serves
+as an essential host, within which an important part of the life cycle
+of the parasite is undergone. These conclusions were quickly verified by
+Bruce and numerous other workers and are no longer open to question.
+Klein and Taute are even inclined to think that mechanical transmission
+plays practically no role in nature, unless the fly is interrupted while
+feeding and passes immediately to a new animal.
+
+
+TSETSE-FLIES AND SLEEPING SICKNESS OF MAN--About the beginning of the
+present century a hitherto little known disease of man began to attract
+great attention on account of its ravages in Uganda and the region of
+Victoria Nyanza in South Africa. It was slow, insiduous and absolutely
+fatal, characterized in its later stages by dullness, apathy, and
+finally absolute lethargy all day long, symptoms which gave it the name
+of "sleeping sickness."
+
+It was soon found that the disease was not a new one but that it had
+been known for over a hundred years on the west coast of Africa. Its
+introduction into Central and East Africa and its rapid spread have been
+attributed primarily to the development of the country, the formation of
+new trade routes and the free mingling of native tribes formerly
+isolated. It is estimated that in the first ten years of the present
+century there were approximately two hundred thousand deaths from the
+disease in the Uganda protectorate. In the British province Bugosa, on
+the Victoria Nyanza there were thirty thousand deaths in the period from
+1902-1905.
+
+While the disease is peculiarly African there are a number of instances
+of its accidental introduction into temperate regions. Slaves suffering
+from it were occasionally brought to America in the early part of the
+last century and cases have sometimes been imported into England. In
+none of the cases did the disease gain a foothold or spread at all to
+other individuals.
+
+In 1902 Dutton described a trypanosome, _T. gambiense_, which he and
+Forde had found the year before in the blood of a patient suffering from
+a peculiar type of fever in Gambia. In 1902-1903 Castellani found the
+same parasite in the cerebro-spinal fluid of sleeping-sickness patients
+and definitely reported it as the causative organism of the disease. His
+work soon found abundant confirmation, and it was discovered that the
+sleeping sickness was but the ultimate phase of the fever discovered by
+Dutton and Forde.
+
+When Castellani made known his discovery of the trypanosome of sleeping
+sickness, Brumpt, in France, and Sambon, in England, independently
+advanced the theory that the disease was transmitted by the tsetse-fly,
+_Glossina palpalis_. This theory was based upon the geographical
+distribution and epidemiology of the disease. Since then it has been
+abundantly verified by experimental evidence.
+
+Fortunately for the elucidation of problems relating to the methods of
+transfer of sleeping sickness, _Trypanosoma gambiense_ is pathogenic for
+many species of animals. In monkeys it produces symptoms very similar to
+those caused in man. Bruce early showed that _Glossina palpalis_ "fed on
+healthy monkeys eight, twelve, twenty-four and forty-eight hours after
+having fed on a native suffering from trypanosomiasis, invariably
+transmitted the disease. After three days the flies failed to transmit
+it." In his summary in Osler's Modern Medicine, he continues "But this
+is not the only proof that these flies can carry the infective agent. On
+the lake shore there was a large native population among whom we had
+found about one-third to be harboring trypanosomes in their blood. The
+tsetse-flies caught on this lake shore, brought to the laboratory in
+cages, and placed straightway on healthy monkeys, gave them the disease
+in every instance, and furnished a startling proof of the danger of
+loitering along the lake shore among those infected flies."
+
+As in the case of nagana, Bruce and most of the earlier investigators
+supposed the transmission of the sleeping sickness trypanosome by
+_Glossina palpalis_ to be purely mechanical. The work of Kleine (1909)
+clearly showed that for _Trypanosoma gambiense_ as well as for
+_Trypanosoma brucei_ the fly served as an essential host. Indeed, Kleine
+and many subsequent investigators are inclined to think that there is
+practically no mechanical transmission of trypanosomes from animal to
+animal by _Glossina_ in nature, and that the many successful experiments
+of the earlier investigators were due to the fact that they used wild
+flies which already harbored the transformed parasite rather than
+directly inoculated it from the blood of the diseased experimental
+animals. While the criticism is applicable to some of the work, this
+extreme view is not fully justified by the evidence at hand.
+
+Kleine states (1912) that _Glossina palpalis_ can no longer be regarded
+as the sole transmitter of sleeping sickness. Taute (1911) had shown
+that under experimental conditions _Glossina morsitans_ was capable of
+transferring the disease and Kleine calls attention to the fact that in
+German East Africa, in the district of the Rovuma River, at least a
+dozen cases of the disease have occurred recently, though only _Glossina
+morsitans_ exists in the district. It appears, however, that these cases
+are due to a different parasite, _Trypanosoma rhodesiense_. This
+species, found especially in north-east Rhodesia and in Nyassaland, is
+transferred by _Glossina morsitans_.
+
+Other workers maintain that the disease may be transmitted by various
+blood-sucking flies, or even bugs and lice which attack man. Fulleborn
+and Mayer (1907) have shown by conclusive experiments that _Aedes
+(Stegomyia) calopus_ may transmit it from one animal to another if the
+two bites immediately succeed each other.
+
+It is not possible that insects other than the tsetse-flies (and only
+certain species of these), play an important role in the transmission of
+the disease, else it would be much more wide-spread. Sambon (1908)
+pointed out that the hypothesis that is spread by _Aedes calopus_ is
+opposed by the fact that the disease never spread in the Antilles,
+though frequently imported there by West African slaves. The same
+observation would apply also to conditions in our own Southern States in
+the early part of the past century.
+
+Since _Glossina palpalis_ acts as an essential host of the parasite and
+the chief, if not the only, transmitter, the fight against sleeping
+sickness, like that against malaria and yellow fever, becomes primarily
+a problem in economic entomology. The minutest detail of the
+life-history, biology, and habits of the fly, and of its parasites and
+other natural enemies becomes of importance in attempts to eradicate the
+disease. Here we can consider only the general features of the subject.
+
+_Glossina palpalis_ lives in limited areas, where the forest and
+undergrowth is dense, along the lake shore or river banks. According to
+Hodges, the natural range from shore is under thirty yards, though the
+distance to which the flies may follow man greatly exceed this.
+
+It is a day feeder, a fact which may be taken advantage of in avoiding
+exposure to its attacks. The young are brought forth alive and
+full-grown, one every nine or ten days. Without feeding, they enter the
+ground and under favorable conditions, complete their development in a
+month or more.
+
+[Illustration: 137. Sleeping sickness concentration camp in German East
+Africa. Report of German Commission.]
+
+Methods of control of the disease must look to the prevention of
+infection of the flies, and to their avoidance and destruction. Along
+the first line, much was hoped from temporary segregation of the sick in
+regions where the fly was not found. On the assumption that the flies
+acted as carriers only during the first two or three days, it was
+supposed that even the "fly belts" would become safe within a few days
+after the sick were removed. The problem was found to be a much more
+difficult one when it was learned that after a given brief period the
+fly again became infective and remained so for an indeterminate period.
+Nevertheless, isolation of the sick is one of the most important
+measures in preventing the spread of the disease into new districts.
+Much, too, is being accomplished by moving native villages from the fly
+belts. (c.f. fig. 137.)
+
+All measures to avoid the flies should be adopted. This means locating
+and avoiding the fly belts as far as possible, careful screening of
+houses, and protection of the body against bites.
+
+Clearing the jungle along the water courses for some yards beyond the
+natural range of the fly has proved a very important measure. Castellani
+recommends that the area be one hundred yards and around a village three
+hundred yards at least.
+
+Detailed studies of the parasites and the natural enemies of the
+tsetse-fly are being undertaken and may ultimately yield valuable
+results.
+
+
+SOUTH AMERICAN TRYPANOSOMIASIS--The tsetse-flies are distinctively
+African in distribution and until recently there were no trypanosomes
+known to infest man in America. In 1909 Dr. Chagas, of Rio de Janeiro
+described a new species, _Trypanosoma cruzi_, pathogenic to man.
+
+_Trypanosoma cruzi_ is the causative organism of a disease common in
+some regions of Brazil, where it is known as "opilacao." It is
+especially to be met with in children and is characterized by extreme
+anemia, wasting, and stunted development associated with fever, and
+enlargement of the thyroid glands. The disease is transmitted by the
+bites of several species of assassin-bugs, or Reduviidae, notably by
+_Conorhinus megistus_. The evolution of the parasite within the bug has
+been studied especially by Chagas and by Brumpt. From the latter's text
+we take the following summary.
+
+The adult trypanosomes, ingested by a _Conorhinus megistus_, of any
+stage, first change into Crithidia-like forms and then those which
+remain in the stomach become ovoid and non-motile. Brumpt found these
+forms in immense numbers, in a _Conorhinus_ which had been infested
+fourteen months before. The forms which pass into the intestine quickly
+assume the _Crithidia_ form and continue to develop rapidly under this
+form. Some weeks later they evolve into the trypanosome forms,
+pathogenic for man. They then pass out with the excrement of the bug and
+infect the vertebrate host as soon as they come in contact with any
+mucous layer (buccal, ocular or rectal). More rarely they enter through
+the epidermis.
+
+Brumpt showed that the development could take place in three species;
+bed-bugs (_Cimex lectularius_, _C. hemipterus_) and in the tick
+_Ornithodoros moubata_. The evolution proceeds in the first two species
+of bed-bugs as rapidly as in Conorhinus, or even more rapidly, but they
+remain infective for a much shorter time and hence Brumpt considers that
+they play a much less important role in the spread of the disease.
+
+_Conorhinus megistus_, like related forms in our Southern States, very
+commonly frequents houses and attacks man with avidity. Chagas states
+that the bites are painless and do not leave any traces. They are
+usually inflicted on the lips, or the cheeks and thus the buccal mucosa
+of a sleeper may be soiled by the dejections of the insect and the bite
+serving as a port of entry of the virus, remain unnoticed.
+
+The possibility of some of our North American Reduviidae playing a
+similar role in the transmission of disease should not be overlooked.
+
+
+LEISHMANIOSES AND INSECTS--Closely related to the trypanosomes is a
+group of intracellular parasites which have recently been grouped by
+Ross under the genus _Leishmania_. Five species are known to affect man.
+Three of these produce local skin infestations, but two of them,
+_Leishmania donovani_ and _L. infantum_, produce serious and often fatal
+systemic diseases.
+
+The first of these, that produced by _L. donovani_, is an exceedingly
+virulent disease common in certain regions of India and China. It is
+commonly known as "Kala-azar," or "dum-dum" fever, and more technically
+as tropical leishmaniasis. Patton (1907) believes that the parasite is
+transmitted by the bed-bug _Cimex hemipterus_, and has described a
+developmental cycle similar to that which can be found in artificial
+cultures. On the other hand, Donovan was unable to confirm Patton's work
+and believes that the true intermediate host is a Reduviid bug,
+_Conorhinus rubrofasciatus_.
+
+_Leishmania infantum_ is the cause of the so-called infantile splenic
+leishmaniasis, occurring in northern Africa, Spain, Portugal, Italy, and
+possibly other parts of Europe. The parasite occurs habitually in the
+dog and is only accidentally transferred to children. Alvares and da
+Silva, in Portugal (according to Brumpt, 1913) have found that the
+excrement of a flea from a diseased dog contains flagellates, and they
+suggest that the infection may be transmitted by the accidental
+inoculation of this excrement by means of the proboscis of the flea, as
+has been thought to occur in the case of the plague. To this Brumpt
+objects that they and other workers who thought to trace the development
+of _Leishmania infantum_ were apparently misled by the presence of a
+harmless _Herpetomonas_ which infests dog fleas in all countries, even
+where the leishmaniasis is unknown.
+
+Basile (1910 and 1911) however, carried on numerous experiments
+indicating that the disease was transferred from children to dogs and
+from dog to dog by the dog flea, and was able to find in the tissues of
+the insects forms perfectly identical with those found in children and
+in dogs suffering from leishmaniasis. He also found that _Pulex
+irritans_ was capable of acting as the carrier.
+
+Of the cutaneous type of leishmaniasis, the best known is the so-called
+"Oriental sore," an ulcerative disease of the skin which is epidemic in
+many tropical and subtropical regions. The causative organism is
+_Leishmania tropica_, which occurs in the diseased tissues as bodies
+very similar to those found in the spleen in cases of Kala-azar. The
+disease is readily inoculable and there is no doubt that it may be
+transferred from the open sores to abraded surfaces of a healthy
+individual by house-flies. It is also believed by a number of
+investigators that it may be transferred and directly inoculated by
+various blood-sucking insects.
+
+
+TICKS AND DISEASES OF MAN AND ANIMALS
+
+We have seen that the way to the discoveries of the relations of
+arthropods to disease was pointed out by the work of Leuckart and
+Melnikoff on the life cycle of _Dipylidium_, and of Fedtschenko and
+Manson on that of _Filaria_. They dealt with grosser forms, belonging to
+well-recognized parasitic groups.
+
+This was long before the role of any insect as a carrier of pathogenic
+micro-organisms had been established, and before the Protozoa were
+generally regarded as of importance in the causation of disease. The
+next important step was taken in 1889 when Smith and Kilbourne
+conclusively showed that the so-called Texas fever of cattle, in the
+United States, is due to an intracorpuscular blood parasite transmitted
+exclusively by a tick. This discovery, antedating by eight years the
+work on the relation of the mosquito to malaria, had a very great
+influence on subsequent studies along these lines.
+
+While much of the recent work has dealt with the true insects, or
+hexapods, it is now known that several of the most serious diseases of
+animals, and at least two important diseases of man are tick borne.
+These belong to the types known collectively as _babesioses_ (or
+"_piroplasmoses_"), and _spirochaetoses_.
+
+The term _babesiosis_ is applied to a disease of man or animals which is
+caused by minute protozoan parasites of the genus _Babesia_, living in
+the red blood corpuscles. These parasites have usually been given the
+generic name _Piroplasma_ and hence the type of disease which they cause
+is often referred to as "_piroplasmosis_." The best known illustration
+is the disease known in this country as Texas fever of cattle.
+
+
+CATTLE TICKS AND TEXAS FEVER--The cattle disease, which in the United
+States is known as Texas fever, is a widely distributed, exceedingly
+acute disease. In Australia it is known as _redwater fever_ and in
+Europe as haemoglobinuria, due to the fact that the urine of the diseased
+animals is discolored by the breaking down of the red blood corpuscles
+infested by the parasite.
+
+In their historical discussion, Smith and Kilbourne, point out that as
+far back as 1796 it was noted that Southern cattle, in a state of
+apparent health, might spread a fatal disease among Northern herds. As
+observations accumulated, it was learned that this infection was carried
+only during the warm season of the year and in the depth of winter
+Southern cattle were harmless. Moreover, Southern cattle after remaining
+for a short time in the North lost their power to transmit the disease,
+and the same was true of cattle which had been driven for a considerable
+distance.
+
+Very significant was the fact that the infection was not communicated
+directly from the Southern to Northern cattle but that the ground over
+which the former passed was infected by them, and that the infection was
+transmitted thence to susceptible cattle _after a period of not less
+than thirty days had elapsed_.
+
+Of course a disease as striking as this, and which caused such enormous
+losses of cattle in the region invaded was fruitful in theories
+concerning its causation. The most widespread was the belief that
+pastures were infected by the saliva, urine, or manure of Southern
+cattle. There were not wanting keen observers who suggested that the
+disease was caused by ticks, but little weight was given to their view.
+
+Various workers had described bacteria which they had isolated from the
+organs of the diseased animals, but their findings could not be
+verified. In 1889, Smith and Kilbourne discovered a minute, pear-shaped
+organism (fig. 138) in the red blood corpuscles of a cow which had
+succumbed to Texas fever. On account of their shape they were given the
+generic name _Pyrososma_ and because they were usually found two in a
+corpuscle, the specific name, _bigeminum_. It is now generally accepted
+that the parasite is the same which Babes had observed the year before
+in Roumanian cattle suffering from haemoglobinuria, and should be known
+as _Babesia bovis_ (Babes).
+
+[Illustration: 138. Babesia bovis in blood corpuscles. After Calli.]
+
+[Illustration: 139. The cattle tick (Boophilus annulatus). (_a_) Female;
+(_b_) male. After Comstock.]
+
+By a series of perfectly conclusive experiments carried on near
+Washington, D.C., Smith and Kilbourne showed that this organism was
+carried from Southern cattle to non-immune animals by the so-called
+Southern cattle tick, _Boophilus annulatus_ (= _Margaropus annulatus_)
+(fig. 139).
+
+Of fourteen head of native cattle placed in a field with tick-infested
+Northern cattle all but two contracted the disease. This experiment was
+repeated with similar results. Four head of native cattle kept in a plot
+with three North Carolina cattle which had been carefully freed from
+ticks remained healthy. A second experiment the same year gave similar
+results.
+
+Still more conclusive was the experiment showing that fields which had
+not been entered by Southern cattle but which had been infected by
+mature ticks taken from such animals would produce Texas fever in native
+cattle. On September 13, 1889, several thousand ticks collected from
+cattle in North Carolina three and four days before, were scattered in a
+small field near Washington. Three out of four native animals placed in
+this field contracted the disease. The fourth animal was not examined as
+to its blood but it showed no external symptoms of the disease.
+
+[Illustration: 140. Hyalomma aegypticum. After Nuttall and Warburton.]
+
+In these earlier experiments it was believed that the cattle tick acted
+as a carrier of the disease between the Southern cattle and the _soil_
+of the Northern pastures. "It was believed that the tick obtained the
+parasite from the blood of its host and in its dissolution on the
+pasture a certain resistant spore form was set free which produced the
+disease when taken in with the food." The feeding of one animal for some
+time with grass from the most abundantly infected field, without any
+appearance of the disease, made this hypothesis untenable.
+
+In the experimental work in 1890 the astonishing fact was brought out
+that the disease was conveyed neither by infected ticks disintegrating
+nor by their directly transferring the parasite, but that it was
+conveyed by the young hatched from eggs of infected ticks. In other
+words, the disease was hereditarily transferred to ticks of the second
+generation and they alone were capable of conveying it.
+
+Thus was explained the fact that Texas fever did not appear immediately
+along the route of Southern cattle being driven to Northern markets but
+that after a certain definite period it manifested itself. It was
+conveyed by the progeny of ticks which had dropped from the Southern
+cattle and deposited their eggs on the ground.
+
+These results have been fully confirmed by workers in different parts of
+the world,--notably by Koch, in Africa, and by Pound, in Australia.
+
+The disease is apparently transmitted by _Boophilus annulatus_ alone, in
+the United States, but it, or an almost identical disease, is conveyed
+by _Ixodes hexagonus_ in Norway, _Ixodes ricinus_ in Finland and France
+and by the three species, _Boophilus decoloratus_, _Hyalomma aegypticum_
+(fig. 140 and 141), and _Haemaphysalis punctata_ in Africa.
+
+[Illustration: 141. Hyalomma aegypticum. Capitulum of female; (_a_)
+dorsal, (_b_) ventral aspect.]
+
+In spite of the detailed study which it has received, the life cycle of
+_Babesia bovis_ has not been satisfactorily worked out. The asexual
+reproduction in the blood of the vertebrate host has been described but
+the cycle in the tick is practically unknown.
+
+More successful attempts have been made to work out the life cycle of a
+related species, _Babesia canis_, which causes malignant jaundice in
+dogs in Africa and parts of Southern Europe. In this instance, also, the
+disease is transmitted by heredity to the ticks of the second
+generation. Yet the larval, or "seed ticks," from an infected female are
+not capable of conveying the disease, but only the nymphs and adults.
+Still more complicated is the condition in the case of _Babesia ovis_ of
+sheep, which Motas has shown can be conveyed solely by the adult,
+sexually mature ticks of the second generation.
+
+In _Babesia canis_, Christopher (1907) observed developmental stages in
+the tick. He found in the stomach of adult ticks, large motile
+club-shaped bodies which he considered as ookinetes. These bodies pass
+to the ovaries of the tick and enter the eggs where they become globular
+in form and probably represent an oocyst. This breaks up into a number
+of sporoblasts which enter the tissues of the developing tick and give
+rise to numerous sporozoites, which collect in the salivary glands and
+thence are transferred to the vertebrate host. A number of other species
+of _Babesia_ are known to infest vertebrates and in all the cases where
+the method has been worked out it has been found that the conveyal was
+by ticks. We shall not consider the cases more fully here, as we are
+concerned especially with the method of transfer of human diseases.
+
+
+TICKS AND ROCKY MOUNTAIN SPOTTED FEVER OF MAN--Ever since 1873 there has
+been known in Montana and Idaho a peculiar febrile disease of man, which
+has gained the name of "Rocky Mountain spotted fever." Its onset is
+marked by chills and fever which rapidly become acute. In about four to
+seven days there appears a characteristic eruption on the wrists, ankles
+or back, which quickly covers the body.
+
+McClintic (1912) states that the disease has now been reported from
+practically all of the Rocky Mountain States, including Arizona,
+California, Colorado, Idaho, Montana, Nevada, Oregon, Utah, Washington,
+and Wyoming. "Although the disease is far more prevalent in Montana and
+Idaho than in any of the other States, its spread has assumed such
+proportions in the last decade as to call for the gravest consideration
+on the part of both the state and national health authorities. In fact,
+the disease has so spread from state to state that it has undoubtedly
+become a very serious interstate problem demanding the institution of
+measures for its control and suppression."
+
+A peculiar feature of the Rocky Mountain spotted fever is a marked
+variation in its severity in different localities. In Montana, and
+especially in the famous Bitter Root Valley, from 33 per cent to 75 per
+cent of the cases result fatally. On the other hand, the fatality does
+not exceed four per cent in Idaho.
+
+In 1902, Wilson and Chowning reported the causative organism of spotted
+fever to be a blood parasite akin to the _Babesia_ of Texas fever, and
+made the suggestion that the disease was tick-borne. The careful studies
+of Stiles (1905) failed to confirm the supposed discovery of the
+organism, and the disease is now generally classed as due to an
+invisible virus. On the other hand, the accumulated evidence has fully
+substantiated the hypothesis that it is tick-borne.
+
+According to Ricketts (1907) the experimental evidence in support of
+this hypothesis was first afforded by Dr. L. P. McCalla and Dr. H. A.
+Brereton, in 1905. These investigators transmitted the disease from man
+to man in two experiments. "The tick was obtained 'from the chest of a
+man very ill with spotted fever' and 'applied to the arm of a man who
+had been in the hospital for two months and a half, and had lost both
+feet from gangrene due to freezing.' On the eighth day the patient
+became very ill and passed through a mild course of spotted fever,
+leaving a characteristic eruption. The experiment was repeated by
+placing the tick on a woman's leg and she likewise was infected with
+spotted fever."
+
+The most detailed studies were those of the late Dr. H. T. Ricketts, and
+it was he who clearly established the tick hypothesis. In the summer of
+1906 he found that guinea pigs and monkeys are very susceptible to
+spotted fever and can readily be infected by inoculation of blood from
+patients suffering from the disease. This opened the way to experimental
+work on tick transmission. A female tick was fed upon an infected guinea
+pig for two days, removed and isolated for two days and then placed upon
+a healthy guinea pig. After an incubation period of three and a half
+days the experimental animal contracted a well-marked case of the
+disease.
+
+A similar result was obtained at the same time by King, and later in the
+season Ricketts proved that the male tick was also capable of
+transmitting the disease. He found that there was a very intimate
+relation of the virus to the tick and that the transmission must be
+regarded as biological throughout. Ticks remained infective as long as
+they lived and would feed for a period of several months. If they
+acquired the disease in the larval or nymphal stage they retained it
+during molting and were infective in the subsequent stages. In a few
+cases the larvae from an infected female were infective.
+
+The evidence indicated that the tick suffers from a relatively harmless,
+generalized infection and the virus proliferates in its body. The
+disease probably is transferred through the salivary secretion of the
+tick since inoculation experiments show that the salivary glands of the
+infected adult contain the virus.
+
+It is probable that in nature the reservoir of the virus of spotted
+fever is some one or more of the native small animals. Infected ticks
+have been found in nature, and as various wild animals are susceptible
+to the disease, it is obvious that it may exist among them unnoticed.
+Wilson and Chowning suggested that the ground squirrel plays the
+principal role.
+
+Unfortunately, much confusion exists regarding the correct name of the
+tick which normally conveys the disease. In the medical literature it is
+usually referred to as _Dermacentor occidentalis_, but students of the
+group now agree that it is specifically distinct. Banks has designated
+it as _Dermacentor venustus_ and this name is used in the publications
+of the Bureau of Entomology. On the other hand, Stiles maintains that
+the common tick of the Bitter Root Valley, and the form which has been
+collected by the authors who have worked on Rocky Mountain spotted fever
+in that region, is separable from _D. venustus_, and he has described it
+under the name of _Dermacentor andersoni_.
+
+Mayer (1911) has shown experimentally that spotted fever may be
+transmitted by several different species of ticks, notably _Dermacentor
+marginatus_, _Dermacentor variabilis_ and _Amblyomma americanum_. This
+being the case, the question of the exact systematic status of the
+species experimented upon in the Bitter Root Valley becomes less
+important, for since _Dermacentor occidentalis_, _Dermacentor venustus_
+and _Dermacentor andersoni_ all readily attack man, it is probable that
+either species would readily disseminate the disease if it should spread
+into their range.
+
+Hunter and Bishop (1911) have emphasized the fact that in the eastern
+and southern United States there occur several species which attack man,
+and any one of which might transmit the disease from animal to animal
+and from animal to man. The following species, they state, would
+probably be of principal importance in the Southern and Eastern States:
+the lone star tick (_Amblyomma americanum_); the American dog tick
+(_Dermacentor variabilis_); and the gulf-coast tick (_Amblyomma
+maculatum_). In the extreme southern portions of Texas, _Amblyomma
+cajennense_, is a common pest of man.
+
+Since the evidence all indicates that Rocky Mountain spotted fever is
+transmitted solely by the tick, and that some of the wild animals serve
+as reservoirs of the virus, it is obvious that personal prophylaxis
+consists in avoiding the ticks as fully as possible, and in quickly
+removing those which do attack. General measures along the line of tick
+eradication must be carried out if the disease is to be controlled. That
+such measures are feasible has been shown by the work which has been
+done in controlling the tick-borne Texas fever of cattle, and by such
+work as has already been done against the spotted fever tick, which
+occurs on both wild and domestic animals. Detailed consideration of
+these measures is to be found in the publications of the Public Health
+and Marine Hospital Service, and the Bureau of Entomology. Hunter and
+Bishopp give the following summarized recommendations for control or
+eradication measures in the Bitter Root Valley.
+
+(1) A campaign of education, whereby all the residents of the valley
+will be made thoroughly familiar with the feasibility of the plan of
+eradication, and with what it will mean in the development of the
+valley.
+
+(2) The obtaining of legislation to make it possible to dip or oil all
+live stock in the Bitter Root Valley.
+
+(3) The obtaining of an accurate census of the horses, cattle, sheep,
+mules, and dogs in the valley.
+
+(4) The construction of ten or more dipping vats.
+
+(5) The providing of materials to be used in the dipping mixture.
+
+(6) The organization of a corps of workers to carry on the operations.
+
+(7) The systematic dipping of the horses, cattle, sheep, and dogs of the
+valley on a definite weekly schedule from approximately March 10 to June
+9.
+
+(8) The treatment by hand of the animals in localities remote from vats,
+on the same schedule.
+
+They estimate that after three seasons' operations a very small annual
+expenditure would provide against reinfestation of the valley by the
+incoming of cattle from other places.
+
+Supplementary measures consist in the killing of wild mammals which may
+harbor the tick; systematic burning of the brush and debris on the
+mountain side; and in clearing, since the tick is seldom found on land
+under cultivation.
+
+
+
+
+CHAPTER X
+
+ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTOZOA [_Continued_]
+
+
+ARTHROPODS AND SPIROCHAETOSES OF MAN AND ANIMALS
+
+The term spirochaetoses is applied to diseases of man or animals which
+are due to protistan parasites belonging to the group of slender, spiral
+organisms known as spirochaetes.
+
+There has been much discussion concerning the relationship Of the
+spirochaetes. Formerly, they were regarded as bacteria closely related to
+the forms grouped in the genus _Spirillum_. The results of the detailed
+study which the spirochaetes have received in recent years, have led most
+of the workers to consider them as belonging to the protozoa. The merits
+of the discussion we are not concerned with here, but rather with the
+fact that a number of diseases caused by spirochaetes are
+arthropod-borne. The better known of these we shall discuss.
+
+
+AFRICAN RELAPSING FEVER OF MAN--It has long been known to the natives of
+Africa and to travelers in that country, that the bite of a certain
+tick, _Ornithodoros moubata_, may be followed by severe or even fatal
+fever of the relapsing type. Until recent years, it was supposed that
+the effect was due to some special virulence of the tick, just as nagana
+of cattle was attributed to the direct effect of the bite of the
+tsetse-fly. The disease is commonly known as "tick-fever" or by the
+various native names of the tick.
+
+In 1904, Ross and Milne, in Uganda, and Dutton and Todd on the Congo,
+discovered that the cause of the disease is a spirochaete which is
+transmitted by the tick. This organism has been designated by Novy and
+Knapp as _Spirochaeta duttoni_.
+
+_Ornithodoros moubata_ (fig. 142), the carrier of African relapsing
+fever, or "tick-fever," is widely distributed in tropical Africa, and
+occurs in great numbers in the huts of natives, in the dust, cracks and
+crevices of the dirt floors, or the walls. It feeds voraciously on man
+as well as upon birds and mammals. Like others of the _Argasidae_, it
+resembles the bed-bug in its habit of feeding primarily at night. Dutton
+and Todd observed that the larval stage is undergone in the egg and that
+the first free stage is that of the octopod nymph.
+
+[Illustration: 142. Ornithodoros moubata. (_a_) Anterior part of venter;
+(_b_) second stage nymph; (_c_) capitulum; (_d_) dorsal and (_e_)
+ventral aspect of female; (_f_) ventral aspect of nymph; (_g_) capitulum
+of nymph. After Nuttall and Warburton.]
+
+The evidence that the fever is transmitted by this tick is conclusive.
+Koch found that from five per cent to fifteen per cent, and in some
+places, fifty per cent of the ticks captured, harbored the spirochaete.
+The disease is readily transmitted to monkeys, rats, mice and other
+animals and the earlier experiments along these lines have been
+confirmed by many workers.
+
+Not only are the ticks which have fed on infected individuals capable of
+conveying the disease to healthy animals but they transmit the causative
+organism to their progeny. Thus Mollers (1907), working in Berlin,
+repeatedly infected monkeys through the bites of nymphs which had been
+bred in the laboratory from infected ticks. Still more astonishing was
+his discovery that ticks of the third generation were infective. In
+other words, if the progeny of infected ticks were fed throughout life
+on healthy animals, and on maturity deposited eggs, the nymphs which
+hatched from these eggs would still be capable of carrying the
+infection.
+
+The developmental cycle of the spirochaete within the tick has not been
+fully worked out, though the general conclusions of Leishman (1910) have
+been supported by the recent works of Balfour (1911 and 1912), and
+Hindle (1912), on the life cycle of spirochaetes affecting fowls.
+
+_Spirochaeta duttoni_ ingested by _Ornithodoros moubata_ apparently
+disappear within a few days, but Leishman believed that in reality they
+break up into minute granules which are to be found in the alimentary
+canal, the salivary glands and the Malpighian tubes of the tick. These
+granules, or "coccoid bodies," as Hindle calls them, are supposed to be
+the form in which the spirochaetes infect the new host. We shall see
+later that Marchoux and Couvy (1913) dissent wholly from this
+interpretation.
+
+According to Leishman, and Hindle, the coccoid bodies are not injected
+into the vertebrate host with the saliva of the tick, as are the
+sporozoites of malaria with that of the mosquito. Instead, they pass out
+with the excrement and secondarily gain access to the wound inflicted by
+the tick.
+
+Nuttall (1912) calls attention to the fact that the geographical
+distribution of _Ornithodoros moubata_ is far wider than our present
+records show for the distribution of the relapsing fever in man and that
+there is every reason to fear the extension of the disease. Huts where
+the ticks occur should be avoided and it should be remembered that in
+infected localities there is special danger in sleeping on the ground.
+
+
+EUROPEAN RELAPSING FEVER--There is widely distributed in Europe a type
+of relapsing fever which is caused by _Spirochaeta recurrentis_. It has
+long been supposed that this disease is spread by the bed-bug and there
+is some experimental evidence to show that it may be conveyed by these
+insects.
+
+In 1897, Tictin found that he could infect monkeys by inoculating the
+contents of bed-bugs which had fed upon a patient within forty-eight
+hours. Nuttall, in 1907, in one experiment succeeded in transmitting
+_Spirochaeta recurrentis_ from mouse to mouse by bites of bed-bugs. The
+bugs, thirty-five in number, were transferred at short intervals from
+one mouse to another, not being allowed to take a full meal on the
+first, or infected mouse.
+
+On the other hand, there is much clinical evidence to show that the
+European relapsing fever like various other types of the disease is
+transmitted from man to man by head and body lice (_Pediculus humanus_
+and _Pediculus corporis_).
+
+Interesting supplementary evidence is that of Bayon's observations
+(1912), in Moscow. "Having visited the big municipal night hospitals at
+Moscow I soon noticed that they were kept with such scrupulous
+cleanliness, disinfected so lavishly, the beds of iron, the floor
+cemented, that it was not possible for bed-bugs to thrive to any extent
+on the premises. The people sleeping there were allowed, however, to
+sleep in their own clothes. The introduction of these model homes had
+not had any effect on the incidence of relapsing fever, for the places
+were still hot-beds of the fever during winter. On the other hand,
+though I changed my rooms several times, I found bugs in every
+successive lodging, and I was told in Moscow, this can hardly be
+avoided. Yet no foreigner, or Russian of the better class, ever catches
+relapsing fever. To this may be added the fact that when I asked for
+clothes-lice and promised to pay a kopec for two, the attendants from
+the night hostel brought me next morning a small ounce bottle crammed
+with _Pediculus capitis_ (= _P. humanus_), and _Pediculus vestimentorum_
+(= _P. corporis_) collected off the sleepers. If relapsing fever were
+transmitted by bed-bugs, it would be much more disseminated than it is
+at present in Moscow."
+
+Direct experimental evidence of the agency of lice in transmitting
+relapsing fever is especially clear in the case of a type of the disease
+prevalent in parts of North Africa. We shall consider this evidence
+later.
+
+
+OTHER TYPES OF RELAPSING FEVER OF MAN--In addition to the three types of
+human relapsing fever already referred to, several others have been
+distinguished and have been attributed to distinct species of
+spirochaetes. The various spirochaetoses of man are:
+
+African, caused by _S. duttoni_; European, caused by _S. recurrentis_;
+North African, caused by _S. berbera_; East African, caused by _S.
+rossi_; East Indian, caused by _S. carteri_; North American, caused by
+_S. novyi_; South American, caused by _S. duttoni_ (?).
+
+Nuttall (1912) in his valuable resume of the subject, has emphasized
+that "in view of the morphological similarity of the supposedly
+different species of spirochaetes and their individual variations in
+virulence, we may well doubt if any of the 'species' are valid. As I
+pointed out four years ago, the various specific names given to the
+spirochaetes causing relapsing fever in man may be used merely for
+convenience _to distinguish strains or races_ of different origin. They
+cannot be regarded as valid names, in the sense of scientific
+nomenclature, for virulence and immunity reactions are not adequate
+tests of specificity."
+
+
+NORTH AFRICAN RELAPSING FEVER OF MAN--The type of human relapsing fever
+to be met with in Algeria, Tunis, and Tripoli, is due to a _Spirochaeta_
+to which does not differ morphologically from _Spirochaeta duttoni_, but
+which has been separated on biological grounds as _Spirochaeta berberi_.
+
+Experimenting with this type of disease in Algeria, Sergent and Foly
+(1910), twice succeeded in transmitting it from man to monkeys by
+inoculation of crushed body lice and in two cases obtained infection of
+human subjects who had received infected lice under their clothing and
+who slept under coverings harboring many of the lice which had fed upon
+a patient. Their results were negative with _Argas persicus_, _Cimex
+lectularius_, _Musca domestica_, _Haematopinus spinulosus_ and
+_Ceratophyllus fasciatus_. They found body lice associated with every
+case of relapsing fever which they found in Algeria.
+
+Nicolle, Blaizot, and Conseil (1912) showed that the louse did not
+transmit the parasite by its bite. Two or three hours after it has fed
+on a patient, the spirochaetes begin to break up and finally they
+disappear, so that after a day, repeated examinations fail to reveal
+them. They persist, nevertheless, in some unknown form, for if the
+observations are continued they reappear in eight to twelve days. These
+new forms are virulent, for a monkey was infected by inoculating a
+single crushed louse which had fed on infected blood fifteen days
+before.
+
+Natural infection is indirect. Those attacked by the insect scratch, and
+in this act they excoriate the skin, crush the lice and contaminate
+their fingers. The least abrasion of the skin serves for the entrance of
+the spirochaetes. Even the contact of the soiled fingers on the various
+mucosa, such as the conjunctive of the eye, is sufficient.
+
+As in the case of _Spirochaeta duttoni_, the organism is transmitted
+hereditarily in the arthropod vector. The progeny of lice which have fed
+on infected blood may themselves be infective.
+
+
+SPIROCHAETOSIS OF FOWLS--One of the best known of the spirochaetes
+transmitted by arthropods is _Spirochaeta gallinarum_, the cause of a
+very fatal disease of domestic fowls in widely separated regions of the
+world. According to Nuttall, it occurs in Southeastern Europe, Asia,
+Africa, South America and Australia.
+
+In 1903, Marchoux and Salimbeni, working in Brazil, made the first
+detailed study of the disease, and showed that the causative organism is
+transmitted from fowl to fowl by the tick _Argas persicus_. They found
+that the ticks remained infective for at least five months. Specimens
+which had fed upon diseased birds in Brazil were sent to Nuttall and he
+promptly confirmed the experiments. Since that date many investigators,
+notably Balfour and Hindle, have contributed to the elucidating of the
+life-cycle of the parasite. Since it has been worked out more fully than
+has that of any of the human spirochaetes, we present Hindle's diagram
+(fig. 143) and quote the brief summary from his preliminary paper
+(1911_b_).
+
+"Commencing with the ordinary parasite in the blood of the fowl, the
+spirochaete grows until it reaches a certain length (16-19u) and then
+divides by transverse division. This process is repeated, and is
+probably the only method of multiplication of the parasite within the
+blood. When the spirochaetes disappear from the circulation, some of them
+break up into the coccoid bodies which, however, do not usually develop
+in the fowl. When the spirochaetes are ingested by _Argas persicus_, some
+of them pass through the gut wall into the coelomic fluid. From this
+medium they bore their way into the cells of the various organs of the
+tick and there break up into a number of coccoid bodies. These
+intracellular forms multiply by ordinary fission in the cells of the
+Malpighian tubules and gonads. Some of the coccoid bodies are formed in
+the lumen of the gut and Malpighian tubules. The result is that some of
+the coccoid bodies may be present in the Malpighian secretion and
+excrement of an infected tick and when mixed with the coxal fluid may
+gain entry into another fowl by the open wound caused by the tick's
+bite. They then elongate and redevelop into ordinary spirochaetes in the
+blood of the fowl, and the cycle may be repeated."
+
+[Illustration: 143. Spirochaeta gallinarum. After Hindle.]
+
+Hindle's account is clear cut and circumstantial, and is quite in line
+with the work of Balfour, and of Leishman. Radically different is the
+interpretation of Marchoux and Couvy (1913). These investigators
+maintain that the granules localized in the Malpighian tubules in the
+larvae and, in the adult, also in the ovules and the genital ducts of the
+male and female, are not derived from spirochaetes but that they exist
+normally in many acariens. They interpret the supposed disassociation
+of the spirochaete into granules as simply the first phase, not of a
+process of multiplication, but of a degeneration ending in the death of
+the parasite. The fragmented chromatin has lost its affinity for stains,
+remaining always paler than that of the normal spirochaetes. On the other
+hand, the granules of Leishman stain energetically with all the basic
+stains.
+
+Further, according to Marchoux and Couvy, infection takes place without
+the emission of the coxal fluid and indeed, soiling of the host by the
+coxal fluid diluting the excrement is exceptional. All of the organs of
+the Argasid are invaded by the parasites, but they pass from the
+coelom into the acini of the salivary glands and collect in its
+efferent canal. The saliva serves as the vehicle of infection.
+
+Thus, the question of the life cycle of _Spirochaeta gallinarum_, and of
+spirochaetes in general, is an open one.
+
+It should be noted that _Argas persicus_, the carrier of _Spirochaeta
+gallinarum_, is a common pest of poultry in the southwestern United
+States. Though the disease has not been reported from this country,
+conditions are such that if accidentally introduced, it might do great
+damage.
+
+
+OTHER SPIROCHAETE DISEASES OF ANIMALS--About a score of other blood
+inhabiting spirochaetes have been reported as occurring in mammals, but
+little is known concerning their life-histories. One of the most
+important is _Spirochaeta theileri_ which produces a spirochaetosis of
+cattle in the Transvaal. Theiler has determined that it is transmitted
+by an Ixodid tick, _Margaropus decoloratus_.
+
+
+TYPHUS FEVER AND PEDICULIDAE
+
+Typhus is an acute, and continued fever, formerly epidemically prevalent
+in camps, hospitals, jails, and similar places where persons were
+crowded together under insanitary conditions. It is accompanied by a
+characteristic rash, which gives the disease the common name of
+"spotted" or "lenticular" fever. The causative organism is unknown.
+
+Typhus fever has not generally been supposed to occur in the United
+States, but there have been a few outbreaks and sporadic cases
+recognized. According to Anderson and Goldberger (1912_a_), it has been
+a subject of speculation among health authorities why, in spite of the
+arrival of occasional cases in this country and of many persons from
+endemic foci of the disease, typhus fever apparently does not gain a
+foothold in the United States. These same workers showed that the
+so-called Brill's disease, studied especially in New York City, is
+identical with the typhus fever of Mexico and of Europe.
+
+The conditions under which the disease occurs and under which it spreads
+most rapidly are such as to suggest that it is carried by some parasitic
+insect. On epidemiological grounds the insects most open to suspicion
+are the lice, bed-bugs and fleas.
+
+In 1909, Nicolle, Comte and Conseil, succeeded in transmitting typhus
+fever from infected to healthy monkeys by means of the body louse
+(_Pediculus corporis_). Independently of this work, Anderson and
+Goldberger had undertaken work along this line in Mexico, and in 1910
+reported two attempts to transmit the disease to monkeys by means of
+body lice. The first experiment resulted negatively, but the second
+resulted in a slight rise in temperature, and in view of later results
+it seems that this was due to infection with typhus.
+
+Shortly after, Ricketts and Wilder (1910) succeeded in transmitting the
+disease to the monkey by the bite of body lice in two experiments, the
+lice in one instance deriving their infection from a man and in another
+from the monkey. Another monkey was infected by typhus through the
+introduction of the feces and abdominal contents of infested lice into
+small incisions. Experiments with fleas and bed-bugs resulted
+negatively.
+
+Subsequently, Goldberger and Anderson (1912_b_) indicated that the head
+louse (_Pediculus humanus_) as well, may become infected with typhus. In
+an attempt to transmit typhus fever (Mexican virus) from man to monkey
+by subcutaneous injection of a saline suspension of crushed head lice,
+the monkeys developed a typical febrile reaction with subsequent
+resistance to an inoculation of virulent typhus (Mexican) blood. In one
+of the three experiments to transmit the disease from man to monkey by
+means of the bite of the head louse, the animal bitten by the presumably
+infected head lice proved resistant to two successive immunity tests
+with virulent typhus blood.
+
+In 1910, Ricketts and Wilder reported an experiment undertaken with a
+view to determining whether the young of infected lice were themselves
+infected. Young lice were reared to maturity on the bodies of typhus
+patients, so that if the eggs were susceptible to infection at any stage
+of their development, they would have every opportunity of being
+infected within the ovary. The eggs of these infected lice were
+obtained, they were incubated, and the young lice of the second
+generation were placed on a normal rhesus monkey. The experimenters were
+unable to keep the monkey under very close observation during the
+following three or four weeks, but from the fact that he proved
+resistant to a subsequent immunity test they concluded that he probably
+owed this immunity to infection by these lice of the second generation.
+
+Anderson and Goldberger (1912_b_) object that due consideration was not
+given to the possibility of a variable susceptibility of the monkey to
+typhus. Their similar experiment was "frankly negative."
+
+Prophylaxis against typhus fever is, therefore, primarily a question of
+vermin extermination. A brief article by Dr. Goldberger (1914) so
+clearly shows the practical application of his work and that of the
+other investigators of the subject, that we abstract from it the
+following account:
+
+"In general terms it may be stated that association with a case of
+typhus fever in the absence of the transmitting insect is no more
+dangerous than is association with a case of yellow fever in the absence
+of the yellow fever mosquito. Danger threatens only when the insect
+appears on the scene."
+
+"We may say, therefore, that to prevent infection of the individual it
+is necessary for him only to avoid being bitten by the louse. In theory
+this may readily be done, for we know that the body louse infests and
+attaches itself almost entirely to the body linen, and that boiling
+kills this insect and its eggs. Individual prophylaxis is based
+essentially, therefore, on the avoidance of contact with individuals
+likely to harbor lice. Practically, however, this is not always as easy
+as it may seem, especially under the conditions of such intimate
+association as is imposed by urban life. Particularly is this the case
+in places such as some of the large Mexican cities, where a large
+proportion of the population harbors this vermin. Under such
+circumstances it is well to avoid crowds or crowded places, such as
+public markets, crowded streets, or public assemblies at which the
+'peon' gathers."
+
+"Community prophylaxis efficiently and intelligently carried out is,
+from a certain point of view, probably easier and more effective in
+protecting the individual than is the individual's own effort to guard
+himself. Typhus emphasizes, perhaps better than any other disease, the
+fact that fundamentally, sanitation and health are economic problems. In
+proportion as the economic condition of the masses has improved--that
+is, in proportion as they could afford to keep clean--the notorious
+filth disease has decreased or disappeared. In localities where it still
+prevails, its further reduction or complete eradication waits on a
+further improvement in, or extension of, the improved economic status of
+those afflicted. Economic evolution is very slow process, and, while
+doing what we can to hasten it, we must take such precautions as
+existing conditions permit, looking to a reduction in or complete
+eradication of the disease."
+
+"When possible, public bath houses and public wash houses, where the
+poor may bathe and do their washings at a minimum or without cost,
+should be provided. Similar provision should be made in military and
+construction camps. Troops in the field should be given the opportunity
+as frequently as possible to wash and _scald_ or _boil_ their body
+linen."
+
+"Lodging houses, cheap boarding houses, night shelters, hospitals, jails
+and prisons, are important factors in the spread and frequently
+constitute foci of the disease. They should receive rigid sanitary
+supervision, including the enforcement of measures to free all inmates
+of such institutions of lice on admission."
+
+"So far as individual foci of the disease are concerned these should be
+dealt with by segregating and keeping under observation all exposed
+individuals for 14 days--the period of incubation--from the last
+exposure, by disinfecting (boiling or steaming) the suspected bedding,
+body linen, and clothes, for the destruction of any possible vermin that
+they may harbor, and by fumigating (with sulphur) the quarters that they
+may have occupied."
+
+"It will be noted that nothing has been said as to the disposition of
+the patient. So far as the patient is concerned, he should be removed to
+'clean' surroundings, making sure that he does not take with him any
+vermin. This may be done by bathing, treating the hair with an
+insecticide (coal oil, tincture of larkspur), and a complete change of
+body linen. Aside from this, the patient may be treated or cared for in
+a general hospital ward or in a private house, provided the sanitary
+officer is satisfied that the new surroundings to which the patient has
+been removed are 'clean,' that is, free from vermin. Indeed, it is
+reasonably safe to permit a 'clean' patient to remain in his own home if
+this is 'clean,' for, as has already been emphasized, there can be no
+spread in the absence of lice. This is a common experience in native
+families of the better class and of Europeans in Mexico City."
+
+"Similarly the sulphur fumigation above prescribed may be dispensed with
+as unnecessary in this class of cases."
+
+
+
+
+CHAPTER XI
+
+SOME POSSIBLE, BUT IMPERFECTLY ESTABLISHED CASES OF ARTHROPOD
+TRANSMISSION OF DISEASE
+
+
+INFANTILE PARALYSIS OR ACUTE ANTERIOR POLIOMYELITIS
+
+The disease usually known in this country as infantile paralysis or,
+more technically, as acute anterior poliomyelitis, is one which has
+aroused much attention in recent years.
+
+The causative organism of infantile paralysis is unknown, but it has
+been demonstrated that it belongs to the group of filterable viruses. It
+gives rise to a general infection, producing characteristic lesions in
+the central nervous system. The result of the injury to the motor nerves
+is a more or less complete paralysis of the corresponding muscle. This
+usually manifests itself in the legs and arms. The fatal cases are
+usually the result of paralysis of the muscles of respiration. Of the
+non-fatal cases about 60 per cent remain permanently crippled in varying
+degrees.
+
+Though long known, it was not until about 1890 that it was emphasized
+that the disease occurs in epidemic form. At this time Medin reported
+his observations on an epidemic of forty-three cases which occurred in
+and around Stockholm in 1887. Since then, according to Frost (1911),
+epidemics have been observed with increasing frequency in various parts
+of the world. The largest recorded epidemics have been those in Vermont,
+1894, 126 cases; Norway and Sweden, 1905, about 1,500 cases; New York
+City, 1907, about 2,500 cases. Since 1907 many epidemics have been
+reported in the United States, and especially in the Northern States
+east of the Dakotas. In 1912 there were over 300 cases of the disease in
+Buffalo, N. Y., with a mortality of somewhat over 11 per cent.
+
+In view of the sudden prominence and the alarming spread of infantile
+paralysis, there have been many attempts to determine the cause, and the
+manner in which the disease spreads and develops in epidemic form. In
+the course of these studies, the question of possible transmission by
+insects was naturally suggested.
+
+C. W. Howard and Clark (1912) presented the results of studies in this
+phase of the subject. They dealt especially with the house-fly, bedbug,
+head, and body lice, and mosquitoes. It was found that the house-fly
+(_Musca domestica_) can carry the virus of poliomyelitis in an active
+state for several days upon the surface of the body and for several
+hours within the gastro-intestinal tract. Mosquitoes and lice were found
+not to take up or maintain the virus. On the other hand, the bedbug
+(_Cimex lectularius_) was found to take the virus from the infected
+monkeys and to maintain it in a living state within the body for a
+period of seven days. This was demonstrated by grinding up in salt
+solution, insects which had fed on poliomyelitic animals and injecting
+the filtrate into a healthy monkey. The experimenters doubted that the
+bedbug is a carrier of the virus in nature.
+
+Earlier in the same year, Brues and Sheppard published the results of an
+intensive epidemiological study of the outbreak of 1911, in
+Massachusetts. Special attention had been paid to the possibility of
+insect transfer and the following conclusion was reached:
+
+"Field work during the past summer together with a consideration of the
+epidemiology of the disease so far as known, points strongly toward
+biting flies as possible carriers of the virus. It seems probable that
+the common stable-fly (_Stomoxys calcitrans_ L.) may be responsible to a
+certain extent for the spread of acute epidemic poliomyelitis, possibly
+aided by other biting flies, such as _Tabanus lineola_. No facts which
+disprove such a hypothesis have as yet been adduced, and experiments
+based upon it are now in progress."
+
+As stated by Brues (1913), especial suspicion fell upon the stable-fly
+because:
+
+1. The blood-sucking habits of the adult fly suit it for the transfer of
+virus present in the blood.
+
+2. The seasonal abundance of the fly is very closely correlated with the
+incidence of the disease, rising rapidly during the summer and reaching
+a maximum in July and August, then slowly declining in September and
+October.
+
+3. The geographical distribution of the fly is, so far as can be
+ascertained, wider, or at least co-extensive with that of poliomyelitis.
+
+4. _Stomoxys_ is distinctly more abundant under rural conditions, than
+in cities and thickly populated areas.
+
+5. While the disease spreads over districts quickly and in a rather
+erratic way, it often appears to follow along lines of travel, and it is
+known that _Stomoxys_ flies will often follow horses for long distances
+along highways.
+
+6. In a surprisingly large number of cases, it appeared probable that
+the children affected had been in the habit of frequenting places where
+_Stomoxys_ is particularly abundant, i.e., about stables, barnyards,
+etc.
+
+The experiments referred to were carried on during the summer of 1912
+and in September Dr. Rosenau announced that the disease was transferred
+by the bite of the stable-fly.
+
+A monkey infected by inoculation was exposed to the bites of upwards of
+a thousand of the _Stomoxys_ flies daily, by stretching it at full
+length and rolling it in a piece of chicken wire, and then placing it on
+the floor of the cage in which the flies were confined. The flies fed
+freely from the first, as well as later, after paralysis had set in.
+Alternating with the inoculated monkey, healthy monkeys were similarly
+introduced into the cage at intervals. New monkeys were inoculated to
+keep a supply of such infected animals and additional healthy ones were
+exposed to the flies, which fed willingly and in considerable numbers on
+each occasion. "Thus the flies were given every opportunity to obtain
+infection from the monkeys, since the animals were bitten during
+practically every stage of the disease from the time of the inoculation
+of the virus till their death following the appearance of paralysis. By
+the same arrangement the healthy monkeys were likely to be bitten by
+flies that had previously fed during the various stages of the disease
+on the infected monkeys. The flies had meanwhile enjoyed the opportunity
+of incubating the virus for periods varying from the day or two which
+usually elapses between consecutive feedings, to the two or three-week
+period for which at least some (although a very small percentage) of the
+flies lived in the cage."
+
+"In all, twelve apparently healthy monkeys of a small Japan species were
+exposed to the flies in the manner described for the infected monkeys.
+Some were placed in the cage only once or twice and others a number of
+times after varying intervals. These exposures usually lasted for about
+half an hour, but were sometimes more protracted. No results were
+apparent until two or three weeks after the experiment was well under
+way, and then in rather rapid succession six of the animals developed
+symptoms of poliomyelitis. In three, the disease appeared in a virulent
+form, resulting in death, while the other three experienced transient
+tremblings, diarrhoea, partial paralysis and recovery."--Brues, 1913.
+
+Very soon after the announcement of the results of experiments by
+Rosenau and Brues, they were apparently conclusively confirmed by
+Anderson and Frost (1912), who repeated the experiments, at Washington.
+They announced that through the bites of the _Stomoxys_ flies that had
+previously fed on infected monkeys, they had succeeded in experimentally
+infecting three healthy monkeys.
+
+The results of these experiments gained much publicity and in spite of
+the conservative manner in which they had been announced, it was widely
+proclaimed that infantile paralysis was conveyed in nature by the
+stable-fly and by it alone.
+
+Serious doubt was cast on this theory by the results of further
+experiments by Anderson and Frost, reported in May of 1913. Contrary to
+the expectations justified by their first experience, the results of all
+the later, and more extended, experiments were wholly negative. Not once
+were these investigators again able to transmit the infection of
+poliomyelitis through _Stomoxys_. They concluded that it was extremely
+doubtful that the insect was an important factor in the natural
+transmission of the disease, not only because of their series of
+negative results, "but also because recent experiments have afforded
+additional evidence of the direct transmissibility or contagiousness of
+poliomyelitis, and because epidemiological studies appear to us to
+indicate that the disease is more likely transmitted largely through
+passive human virus carriers."
+
+Soon after this, Kling and Levaditi (1913) published their detailed
+studies on acute anterior poliomyelitis. They considered that the
+experiments of Flexner and Clark (and Howard and Clark), who fed
+house-flies on emulsion of infected spinal cord, were under conditions
+so different from what could occur in nature that one could not draw
+precise conclusions from them regarding the epidemiology of the disease.
+They cited the experiments of Josefson (1912), as being under more
+reasonable conditions. He sought to determine whether the inoculation of
+monkeys with flies caught in the wards of the Hospital for Contagious
+Diseases at Stockholm, where they had been in contact with cases of
+poliomyelitis, would produce the disease. The results were completely
+negative.
+
+Kling and Lavaditi made four attempts of this kind. The flies were
+collected in places where poliomyelitics had dwelt, three, four and
+twenty-four after the beginning of the disease in the family and one,
+three, and fifteen days after the patient had left the house. These
+insects were for the greater part living and had certainly been in
+contact with the infected person. In addition, flies were used which had
+been caught in the wards of the Hospital for Contagious Diseases at
+Soderkoping, when numbers of poliomyelitics were confined there.
+Finally, to make the conditions as favorable as possible, the emulsions
+prepared from these flies were injected without previous filtering,
+since filtration often causes a weakening of the virus. In spite of
+these precautions, all their results were negative, none of the
+inoculated animals having contracted poliomyelitis. They also
+experimented with bedbugs which had fed upon infected patients at
+various stages of the disease, but the results in these cases also were
+wholly negative.
+
+Kling and Levaditi considered at length the possibility of transmission
+of the disease by _Stomoxys_. As a result of their epidemiological
+studies, they found that infantile paralysis continued to spread in
+epidemic form in the dead of winter, when these flies were very rare and
+torpid, or were even completely absent. Numerous cases developed in the
+northern part of Sweden late in October and November, long after snow
+had fallen. On account of the rarity of the Stomoxys flies during the
+period of their investigations they were unable to conduct satisfactory
+experiments. In one instance, during a severe epidemic, they found a
+number of the flies in a stable near a house inhabited by an infected
+family, though none was found in the house itself. These flies were used
+in preparing an emulsion which, after filtering, was injected into the
+peritoneal cavity of a monkey. The result was wholly negative.
+
+As for the earlier experiments, Kling and Levaditi believe if the flies
+were responsible for the transmission of the disease in the cases
+reported by Rosenau and Brues, and the first experiments of Anderson and
+Frost, it was because the virus of infantile paralysis is eliminated
+with the nasal secretions of paralyzed monkeys and the flies, becoming
+contaminated, had merely acted as accidental carriers.
+
+Still further evidence against the hypothesis of the transmission of
+acute anterior poliomyelitis by _Stomoxys calcitrans_ was brought
+forward by Sawyer and Herms (1913). Special precautions were used to
+prevent the transference of saliva or other possibly infectious material
+from the surface of one monkey to that of another, and to avoid the
+possibility of complicating the experiments by introducing other
+pathogenic organisms from wild flies, only laboratory-bred flies were
+used. In a series of seven carefully performed experiments, in which the
+conditions were varied, Sawyer and Herms were unable to transmit
+poliomyelitis from monkey to monkey through the agency of _Stomoxys_, or
+to obtain any indication that the fly is the usual agent for spreading
+the disease in nature.
+
+The evidence at hand to date indicates that acute anterior
+poliomyelitis, or infantile paralysis, is transmitted by contact with
+infected persons. Under certain conditions insects may be agents in
+spreading the disease, but their role is a subordinate one.
+
+
+Pellagra
+
+PELLAGRA is an endemic and epidemic disease characterized by a peculiar
+eruption or erythema of the skin (figs 144 and 145), digestive
+disturbances and nervous trouble. Insanity is a common result, rather
+than a precursor of the disease. The manifestations of pellagra are
+periodic and its duration indeterminate.
+
+[Illustration: 144. Pellagrous eruption on the face. After Watson.]
+
+The disease is one the very name of which was almost unknown in the
+United States until within the past decade. It has usually been regarded
+as tropical, though it occurs commonly in Italy and in various parts of
+Europe. Now it is known that it not only occurs quite generally in the
+United States but that it is spreading. Lavinder (1911) says that "There
+are certainly many thousand cases of the disease in this country, and
+the present situation must be looked upon with grave concern."
+
+It is not within the scope of this book to undertake a general
+discussion of pellagra. The subject is of such importance to every
+medical man that we cannot do better than refer to Lavinder's valuable
+precis. We can only touch briefly upon the entomological phases of the
+problems presented.
+
+The most commonly accepted theories regarding the etiology of the
+disease have attributed it to the use of Indian corn as an article of
+diet. This supposed relationship was explained either on the basis of,
+(a) insufficiency of nutriment and inappropriateness of corn as a prime
+article of food; (b) toxicity of corn or, (c) parasitism of certain
+organisms--fungi or bacteria--ingested with either sound or deteriorated
+corn.
+
+In 1905, Sambon proposed the theory of the protozoal origin of pellagra
+and in 1910 he marshalled an imposing array of objections to the theory
+that there existed any relationship between corn and the disease. He
+presented clear evidence that pellagra existed in Europe before the
+introduction of Indian corn from America, as an article of diet, and
+that its spread was not _pari passu_ with that of the use of corn. Cases
+were found in which the patients had apparently never used corn, though
+that is obviously difficult to establish. He showed that preventive
+measures based on the theory had been a failure. Finally, he believed
+that the recurrence of symptoms of the disease for successive springs,
+in patients who abstained absolutely from the use of corn, militated
+against the theory.
+
+[Illustration: 145. Pellagrous eruption on the hand. After Watson.]
+
+On the other hand, Sambon believed that the periodicity of the symptoms,
+peculiarities of distribution and seasonal incidence, and analogies of
+the symptoms to those of other parasitic diseases indicated that
+pellagra was of protozoal origin, and that it was insect-borne.
+
+The insect carriers, he believed to be one or more species of Simuliidae,
+or black-flies. In support of this he stated that _Simulium_ appears to
+effect the same topographical conditions as pellagra, that in its imago
+stage it seems to present the same seasonal incidence, that it has a
+wide geographical distribution which seems to cover that of pellagra,
+and that species of the genus are known to cause severe epizootics.
+Concluding from his studies in Italy, that pellagra was limited almost
+wholly to agricultural laborers, he pointed out that the Simulium flies
+are found only in rural districts, and as a rule do not enter towns,
+villages, or houses.
+
+[Illustration: 146. A favorite breeding place of Simulium. Ithaca, N.
+Y.]
+
+When Sambon's detailed report was published in 1910, his theory was
+seized upon everywhere by workers who were anxious to test it and who,
+in most cases, were favorably disposed towards it because of the
+wonderful progress which had been made in the understanding of other
+insect-borne diseases. In this country, the entomological aspects of the
+subject have been dealt with especially by Forbes (1912), and by King
+and Jennings, under the direction of W. D. Hunter, of the Bureau of
+Entomology, and in cooperation with the Thompson-McFadden Pellagra
+Commission of the Department of Tropical Medicine of the New York
+Post-Graduate Medical School. An important series of experiments with
+monkeys has been undertaken by S. J. Hunter, of Kansas, but
+unfortunately we have as yet no satisfactory evidence that these animals
+are susceptible to the disease--a fact which renders the whole problem
+difficult.
+
+The accumulated evidence is increasingly opposed to Sambon's hypothesis
+of the transmission of pellagra by _Simulium_. This has been so clearly
+manifested in the work of the Thompson-McFadden Commission that we quote
+here from the report by Jennings (1914):
+
+"Our studies in 1912 convinced us that there was little evidence to
+support the incrimination of any species of _Simulium_ in South Carolina
+in the transmission of pellagra. Reviewing the group as a whole, we find
+that its species are essentially "wild" and lack those habits of
+intimate association with man which would be expected in the vector of
+such a disease as pellagra. Although these flies are excessively
+abundant in some parts of their range and are moderately so in
+Spartanburg County, man is merely an incidental host, and no disposition
+whatever to seek him out or to invade his domicile seems to be
+manifested. Critically considered, it is nearer the fact that usually
+man is attacked only when he invades their habitat."
+
+"As our knowledge of pellagra accumulates, it is more and more evident
+that its origin is in some way closely associated with the domicile. The
+possibility that an insect whose association with man and his immediate
+environment is, at the best, casual and desultory, can be active in the
+causation of the disease becomes increasingly remote."
+
+"Our knowledge of the biting habits of _Simulium_ is not complete, but
+it is evident, as regards American species at least, that these are
+sometimes not constant for the same species in different localities.
+Certain species will bite man freely when opportunity offers, while
+others have never been known to attack him. To assume that the proximity
+of a _Simulium_-breeding stream necessarily implies that persons in its
+vicinity must be attacked and bitten is highly fallacious. In
+Spartanburg County attacks by _Simulium_ seems to be confined to the
+immediate vicinity of the breeding-places. Our records and observations,
+exceedingly few in number, refer almost exclusively to such locations.
+Statements regarding such attacks, secured with much care and
+discrimination from a large number of persons, including many
+pellagrins, indicate conclusively that these insects are seldom a pest
+of man in this county. A certain number of the persons questioned were
+familiar with the gnats in other localities, but the majority were
+seemingly ignorant of the existence of such flies with biting habits.
+This is especially striking, in view of the fact that the average
+distance of streams from the homes of the pellagra cases studied was
+about 200 yards, many being at a distance of less than 200 yards, and
+that 78 per cent of these streams were found to be infested by larval
+_Simulium_. Such ignorance in a large number of persons cannot be
+overlooked and indicates strongly that our belief in the negligible
+character of local attacks by _Simulium_ is well founded."
+
+"In localities infested by 'sand-flies,' mosquitoes, etc., these pests
+are always well known and the ignorance described above is very
+significant."
+
+"Such positive reports as we received nearly always referred to bites
+received in the open, along streams, etc., and observations made of
+their attack were of those on field laborers in similar situations.
+Males engaged in agricultural pursuits are almost exempt from pellagra
+in Spartanburg County. During the season of 1913, in some two or three
+instances, observations were made of the biting of _Simulium_ and some
+additional and entirely creditable reports were received. These
+observations and reports were under conditions identical with those
+referred to in the reports of 1912 and confirm the conclusions based on
+the observations of that year. I would repeat with emphasis that it is
+inconceivable that a fly of the appearance and habits of the prevalent
+species of _Simulium_ could be present in such a region, especially
+about the haunts of man and attack him with sufficient frequency and
+regularity to satisfactorily account for so active and prevalent a
+disease as pellagra without being a well-known and recognized pest."
+
+"In connection with the conditions in the Piedmont region of South
+Carolina, it may be well to cite the results of a study of those in the
+arid region of western Texas."
+
+"In May, 1913, in company with Capt. J. F. Siler of the
+Thompson-McFadden Pellagra Commission, I visited the region of which
+Midland in Midland County is the center. This region is very dry and
+totally devoid of running water for a long distance in every direction.
+The only natural source of water-supply, a few water holes and ponds,
+were visited and found to be of such a nature that the survival of
+_Simulium_, far less its propagation in them, is absolutely impossible.
+The nearest stream affording possibilities as a source of _Simulium_ is
+60 miles away, while the average distance of such possibility is not
+less than 100 miles."
+
+"Artificial sources of water-supply were also investigated carefully and
+were found to offer no opportunity for the breeding of _Simulium_."
+
+"At Midland the histories of five cases of pellagra were obtained, which
+gave clear evidence that this place or its immediate vicinity was the
+point of origin. Persons of long residence in the country were
+questioned as to the occurrence of such flies as _Simulium_ and returned
+negative answers. These included a retired cattle owner, who is a man of
+education and a keen observer, an expert veterinarian stationed in the
+country who has the cattle of the country under constant observation,
+and a practical cattle man, manager of a ranch and of wide experience.
+The latter had had experience with 'Buffalo gnats' in other localities
+(in the East) and is well acquainted with them. His close personal
+supervision of the cattle under his charge, makes it practically certain
+that he would have discovered these gnats had they been present in the
+country."
+
+"At the time the study was made, _Simulium_ was breeding and active in
+the adult state in the vicinity of Dallas, Texas, in the eastern part of
+the state. We have here a region in which cases of pellagra have
+originated, yet in which _Simulium_ does not and cannot breed."
+
+Other possible insect vectors of pellagra have been studied in great
+detail and the available evidence indicates that if _any_ insect plays a
+role in the spread of the disease, _Stomoxys calcitrans_ most nearly
+fills the conditions. This conclusion was announced by Jennings and King
+in 1912, and has been supported by their subsequent work.
+
+Yet, after all the studies of the past decade, the old belief that
+pellagra is essentially of dietary origin is gaining ground. Goldberger,
+Waring and Willets (1914) of the United States Public Health Service
+summarize their conclusions in the statement, (1) that it is dependent
+on some yet undetermined fault in a diet in which the animal or
+leguminous protein component is disproportionately large and (2) that no
+pellagra develops in those who _consume_ a mixed, well-balanced, and
+varied diet, such, for example, as that furnished by the Government to
+the enlisted men of the Army, Navy, and Marine Corps.
+
+
+Leprosy
+
+LEPROSY is a specific, infectious disease due to _Bacillus leprae_, and
+characterized by the formation of tubercular nodules, ulcerations, and
+disturbances of sensation. In spite of the long time that the disease
+has been known and the dread with which it is regarded, little is known
+concerning the method of transfer of the causative organism or the means
+by which it gains access to the human body.
+
+It is known that the bacilli are to be found in the tubercles, the scurf
+of the skin, nasal secretions, the sputum and, in fact in practically
+all the discharges of the leper. Under such conditions it is quite
+conceivable that they may be transferred in some instances from diseased
+to healthy individuals through the agency of insects and other
+arthropods. Many attempts have been made to demonstrate this method of
+spread of the disease, but with little success.
+
+Of the suggested insect carriers none seem to meet the conditions better
+than mosquitoes, and there are many suggestions in literature that these
+insects play an important role in the transmission of leprosy. The
+literature has been reviewed and important experimental evidence
+presented by Currie (1910). He found that mosquitoes feeding, under
+natural conditions, upon cases of nodular leprosy so rarely, if ever,
+imbibe the lepra bacillus that they cannot be regarded as one of the
+ordinary means of transference of this bacillus from lepers to the skin
+of healthy persons. He believes that the reason that mosquitoes that
+have fed on lepers do not contain the lepra bacillus is that when these
+insects feed they insert their proboscis directly into a blood vessel
+and thus obtain bacilli-free blood, unmixed with lymph.
+
+The same worker undertook to determine whether flies are able to
+transmit leprosy. He experimented with five species found in
+Honolulu,--_Musca domestica_, _Sarcophaga pallinervis_, _Sarcophaga
+barbata_, _Volucella obesa_ and an undetermined species of _Lucilia_.
+The experiments with _Musca domestica_ were the most detailed. From
+these experiments he concluded, first, that all of the above-named
+flies, when given an opportunity to feed upon leprous fluids, will
+contain the bacilli in their intestinal tracts and feces for several
+days after such feeding. Second, that considering the habits of these
+flies, and especially those of _Musca domestica_, it is certain that,
+given an exposed leprous ulcer, these insects will frequently convey
+immense numbers of lepra bacilli, directly or indirectly, to the skins,
+nasal mucosa, and digestive tracts of healthy persons. Additional
+evidence along this line has recently been brought forward by Honeij and
+Parker (1914), who incriminate both _Musca domestica_ and _Stomoxys
+calcitrans_. Whether or not such insect-borne bacilli are capable of
+infecting persons whose skin and mucosa are thus contaminated, Currie
+was unwilling to maintain, but he concludes that until we have more
+accurate knowledge on this point, we are justified in regarding these
+insects with grave suspicion of being one of the means of disseminating
+leprous infection.
+
+Various students of the subject have suggested that bed-bugs may be the
+carriers of leprosy and have determined the presence of acid-fast
+bacilli in the intestines of bed-bugs which had fed on leprous patients.
+Opposed to this, the careful experiments of Thompson (1913) and of
+Skelton and Parkham (1913) have been wholly negative.
+
+Borrel has recently suggested that _Demodex_, may play a role in
+spreading the infection in families. Many other insects and acariens
+have been suggested as possible vectors, but the experimental data are
+few and in no wise conclusive. The most that can be said is that it is
+quite possible that under favorable conditions the infection might be
+spread by any of the several blood-sucking forms or by house-flies.
+
+
+Verruga peruviana
+
+VERRUGA PERUVIANA is defined by Castellani and Chalmers as "a chronic,
+endemic, specific, general disorder of unknown origin, not contagious,
+but apparently inoculable, and characterized by an irregular fever
+associated with rheumatoid pains, anemia, followed by granulomatous
+swellings in the skin, mucous membranes, and organs of the body." It has
+been generally believed by medical men interested that the comparatively
+benign eruptive verruga is identical with the so-called Oroya, or
+Carrion's fever, a malignant type. This view is not supported by the
+work of Strong, Tyzzer and Brues, (1913).
+
+The disease is confined to South America and to definitely limited areas
+of those countries in which it does occur. It is especially prevalent in
+some parts of Peru.
+
+The causative organism and the method of transfer of verruga are
+unknown. Castellani and Chalmers pointed out in 1910 that the study of
+the distribution of the disease in Peru would impress one with the
+similarity to the distribution of the Rocky Mountain fever and would
+lead to the conclusion that the aetiological cause must in some way be
+associated with some blood-sucking animal, perhaps an arachnid, and that
+this is supported by the fact that the persons most prone to the
+infection are those who work in the fields.
+
+More recently, Townsend (1913), in a series of papers, has maintained
+that verruga and Carrion's disease are identical, and that they are
+transmitted to man by the bites of the Psychodid fly, _Phlebotomus
+verrucarum_. He succeeded in producing the eruptive type of the disease
+in experimental animals by injecting a physiological salt trituration of
+wild Phlebotomus flies. A cebus monkey was exposed from October so to
+November 6, by chaining him to a tree in the verruga zone, next to a
+stone wall from which the flies emerged in large numbers every night.
+Miliar eruption began to appear on the orbits November 13 and by
+November 21, there were a number of typical eruptions, with exudation on
+various parts of the body exactly like miliar eruptive sores commonly
+seen on legs of human cases.
+
+An assistant in the verruga work, George E. Nicholson, contracted the
+eruptive type of the disease, apparently as a result of being bitten by
+the Phlebotomus flies. He had slept in a verruga zone, under a tight
+net. During the night he evidently put his hands in contact with the
+net, for in the morning there were fifty-five unmistakable Phlebotomus
+bites on the backs of his hands and wrists.
+
+Townsend believes that in nature, lizards constitute the reservoir of
+the disease and that it is from them that the Phlebotomus flies receive
+the infection.
+
+
+Cancer
+
+There are not wanting suggestions that this dread disease is carried, or
+even caused, by arthropods. Borrel (1909) stated that he had found mites
+of the genus _Demodex_ in carcinoma of the face and of the mammae. He
+believed that they acted as carriers of the virus.
+
+Saul (1910) and Dahl (1910) go much further, since they attribute the
+production of the malignant growth to the presence of mites which Saul
+had found in cancers. These Dahl described as belonging to a new
+species, which he designated _Tarsonemus hominis_. These findings have
+since been confirmed by several workers. Nevertheless, the presence of
+the mite is so rare that it cannot be regarded as an important factor in
+the causation of the disease. The theory that cancer is caused by an
+external parasite is given little credence by investigators in this
+field.
+
+
+IN CONCLUSION, it should be noted that the medical and entomological
+literature of the past few years abounds in suggestions, and in
+unsupported direct statements that various other diseases are
+insect-borne. Knab (1912) has well said "Since the discovery that
+certain blood-sucking insects are the secondary hosts of pathogenic
+parasites, nearly every insect that sucks blood, whether habitually or
+occasionally, has been suspected or considered a possible transmitter of
+disease. No thought seems to have been given to the conditions and the
+characteristics of the individual species of blood-sucking insects,
+which make disease transmission possible."
+
+He points out that "in order to be a potential transmitter of human
+blood-parasites, an insect must be closely associated with man and
+normally have opportunity to suck his blood repeatedly. It is not
+sufficient that occasional specimens bite man, as, for example, is the
+case with forest mosquitoes. Although a person may be bitten by a large
+number of such mosquitoes, the chances that any of these mosquitoes
+survive to develop the parasites in question, (assuming such development
+to be possible), and then find opportunity to bite and infect another
+person, are altogether too remote. Applying this criterion, not only the
+majority of mosquitoes but many other blood-sucking insects, such as
+Tabanidae and Simuliidae, may be confidently eliminated. Moreover,
+these insects are mostly in evidence only during a brief season, so that
+we have an additional difficulty of a very long interval during which
+there could be no propagation of the disease in question." He makes an
+exception of tick-borne diseases, where the parasites are directly
+transmitted from the tick host to its offspring and where, for this
+reason, the insect remains a potential transmitter for a very long
+period. He also cites the trypanosome diseases as possible exceptions,
+since the causative organisms apparently thrive in a number of different
+vertebrate hosts and may be transmitted from cattle, or wild animals, to
+man.
+
+Knab's article should serve a valuable end in checking irresponsible
+theorizing on the subject of insect transmission of disease.
+Nevertheless, the principles which he laid down cannot be applied to the
+cases of accidental carriage of bacterial diseases, or to those of
+direct inoculation of pyogenic organisms, or of blood parasites such as
+the bacillus of anthrax, or of bubonic plague. Accumulated evidence has
+justified the conclusion that certain trypanosomes pathogenic to man are
+harbored by wild mammals, and so form an exception. Townsend believes
+that lizards constitute the natural reservoir of verruga; and it seems
+probable that field mice harbor the organism of tsutsugamushi disease.
+Such instances are likely to accumulate as our knowledge of the relation
+of arthropods to disease broadens.
+
+
+
+
+CHAPTER XII
+
+HOMINOXIOUS ARTHROPODS
+
+
+The following synoptic tables are presented in the hope that they may be
+of service in giving the reader a perspective of the relationships of
+the Arthropoda in general and enabling him to identify the more
+important species which have been found noxious to man. Though
+applicable chiefly to the arthropods found in the United States, exotic
+genera and species which are concerned in the transmission of disease
+are also included. For this reason the keys to the genera of the Muscids
+of the world are given. As will be seen, the tables embrace a number of
+groups of species which are not injurious. This was found necessary in
+order that the student might not be lead to an erroneous determination
+which would result were he to attempt to identify a species which
+heretofore had not been considered noxious, by means of a key containing
+only the noxious forms. The names printed in BOLD FACED TYPE indicate
+the hominoxious arthropods which have been most commonly mentioned in
+literature.
+
+
+CRUSTACEA
+
+Arthropods having two pairs of antennae which are sometimes modified for
+grasping, and usually with more than five pairs of legs. With but few
+exceptions they are aquatic creatures. Representatives are: Crabs,
+lobsters, shrimps, crayfish, water-fleas, and woodlice. To this class
+belongs the CYCLOPS (fig. 122) a genus of minute aquatic crustaceans of
+which at least one species harbors _Dracunculus medinensis_, the Guinea
+worm (fig. 121).
+
+
+MYRIAPODA
+
+Elongate, usually vermiform, wingless, terrestrial creatures having one
+pair of antennae, legs attached to each of the many intermediate body
+segments. This group is divided into two sections, now usually given
+class rank: the DIPLOPODA or millipedes (fig. 13), commonly known as
+thousand legs, characterized by having two pairs of legs attached to
+each intermediate body segment, and the CHILOPODA or centipedes (fig.
+14) having only one pair of legs to each body segment.
+
+
+ARACHNIDA
+
+In this class the antennae are apparently wanting, wings are never
+present, and the adults are usually provided with four pairs of legs.
+Scorpions, harvest-men, spiders, mites, etc.
+
+
+HEXAPODA (Insects)
+
+True insects have a single pair of antennae, which is rarely vestigial,
+and usually one or two pairs of wings in the adult stage. Familiar
+examples are cockroaches, crickets, grasshoppers, bugs, dragon-flies,
+butterflies, moths, mosquitoes, flies, beetles, ants, bees and wasps.
+
+
+ORDERS OF THE ARACHNIDA
+
+a. Abdomen distinctly segmented. A group of orders including scorpions,
+    (fig. 11), whip-scorpions (fig. 10), pseudo-scorpions, solpugids
+    (fig. 12) harvest-men (daddy-long-legs or harvestmen), etc.
+    ARTHROGASTRA
+
+aa. Abdomen unsegmented, though sometimes with numerous annulations
+    SPHAEROGASTRA
+
+  b. A constriction between cephalothorax and abdomen (fig. 7). True
+      Spiders ARANEIDA
+
+  bb. No deep constriction between these parts.
+
+    c. Legs usually well developed, body more or less depressed (fig.
+        49). Mites ACARINA
+
+    cc. Legs stumpy or absent, body more or less elongate or vermiform,
+        or if shorter, the species is aquatic or semi-aquatic in habit.
+
+      d. Four pairs of short legs; species inhabiting moss or water.
+          Water-bears. TARDIGRADA
+
+      dd. Two pairs of clasping organs near the mouth, instead of legs,
+          in the adult; worm-like creatures parasitic within the nasal
+          passages, lungs, etc. of mammals and reptiles (fig. 148).
+          Tongue worms. LINGUATULINA
+
+[Illustration: 148. Linguatula. (_a_) larva; (enlarged). (_b_) adult;
+(natural size).]
+
+
+ACARINA[E]
+
+a. Abdomen annulate, elongate; very minute forms, often with but four
+    legs (fig. 62). DEMODICOIDEA
+
+  b. With but four legs of five segments each. Living on plants, often
+      forming galls. ERIOPHYIDAE
+
+  bb. With eight legs, of three segments each. Living in the skin of
+      mammals. DEMODICIDAE
+
+    To this family belongs the genus DEMODEX found in the sebaceous
+        glands and hair follicles of various mammals, including man. _D.
+        phylloides_ Csokor has been found in Canada on swine, causing
+        white tubercles on the skin. _D. bovis_ Stiles has been reported
+        from the United States on cattle, upon the skin of which they
+        form swellings. D. FOLLICULORUM Simon is the species found on
+        man. See page 78.
+
+aa. Abdomen not annulate nor prolonged behind; eight legs in the adult
+    stage.
+
+  b. With a distinct spiracle upon a stigmal plate on each side of the
+      body (usually ventral) above the third or fourth coxae or a little
+      behind (fig. 50); palpi free; skin often coriaceous or leathery;
+      tarsi often with a sucker.
+
+    c. Hypostome large (fig. 50), furnished below with many recurved
+        teeth; venter with furrows, skin leathery; large forms, usually
+        parasitic. IXODOIDEA
+
+      d. Without scutum but covered by a more or less uniform leathery
+          integument; festoons absent; coxae unarmed, tarsi without
+          ventral spurs; pulvilli absent or vestigial in the adults;
+          palpi cylindrical; sexual dimorphism slight. ARGASIDAE
+
+        e. Body flattened, oval or rounded, with a distinct flattened
+            margin differing in structure from the general integument;
+            this margin gives the body a sharp edge which is not
+            entirely obliterated even when the tick is full fed.
+            Capitulum (in adults and nymphs) entirely invisible
+            dorsally, distant in the adult by about its own length from
+            the anterior border. Eyes absent. ARGUS Latr.
+
+          f. Body oblong; margin with quadrangular cells; anterior tibiae
+              and metatarsi each about three times as long as broad. On
+              poultry, southwest United States. A. PERSICUS MINIATUS
+
+            _A. brevipes_ Banks, a species with proportionately shorter
+                legs has been recorded from Arizona.
+
+          ff. With another combination of characters. About six other
+              species of _Argas_ from various parts of the world,
+              parasitic on birds and mammals.
+
+        ee. Body flattened when unfed, but usually becoming very convex
+            on distention; anterior end more or less pointed and
+            hoodlike; margin thick and not clearly defined, similar in
+            structure to the rest of the integument and generally
+            disappearing on distention; capitulum subterminal, its
+            anterior portions often visible dorsally in the adult; eyes
+            present in some species.
+
+          f. Integument pitted, without rounded tubercles; body provided
+              with many short stiff bristles; eyes absent. On horses,
+              cattle and man (fig. 48). OTIOBIUS Banks.
+
+            O. MEGNINI, a widely distributed species, is the type of
+                this genus.
+
+          ff. Integument with rounded tubercles or granules; body
+              without stiff bristles. ORNITHODOROS Koch.
+
+            g. Two pairs of eyes; tarsi IV with a prominent subterminal
+                spur above; leg I strongly roughened. On cattle and man.
+                O. CORIACEUS
+
+            gg. No eyes; no such spur on the hind tarsi.
+
+              h. Tarsi I without humps above. _O. talaje._
+
+              hh. Tarsi I with humps above.
+
+                i. Tarsi IV without distinct humps above. On hogs,
+                    cattle and man. O. TURICATA
+
+                ii. Tarsi IV with humps nearly equidistant (fig. 142).
+                    Africa. O. MOUBATA
+
+[Illustration: 149. Haemaphysalis wellingtoni. Note short palpi. After
+Nuttall and Warburton.]
+
+      dd. With scutum or shield (fig. 50); festoons usually present;
+          coxae usually armed with spurs, tarsi generally with one or two
+          ventral spurs; pulvilli present in the adults; sexual
+          dimorphism pronounced. IXODIDAE
+
+        e. With anal grooves surrounding anus in front; inornate;
+            without eyes; no posterior marginal festoons; venter of the
+            male with non-salient plates. Numerous species, 14 from the
+            United States, among them I. RICINUS (fig. 49 and 50),
+            SCAPULARIS, COOKEI, _hexagonus_, _bicornis_. IXODES Latr.
+            (including Ceratixodes).
+
+        ee. With anal groove contouring anus behind, or groove faint or
+            obsolete.
+
+          f. With short palpi (fig. 149).
+
+            g. Without eyes, inornate, with posterior marginal festoons;
+                male without ventral plates. Numerous species. _H.
+                chordeilis_ and _leporis-palustris_ from the United
+                States. _Haemaphysalis_ Koch.
+
+[Illustration: 150. Stigmal plate of Dermacentor andersoni; (_a_) of
+male, (_b_) of female. After Stiles. (_c_) Dermacentor variabilis, male;
+(_d_) Glyciphagus obesus; (_e_) Otodectes cynotis; (_f_) Tyroglyphus
+lintneri; (_g_) Tarsonemus pallidus; (_h_) anal plate and mandible of
+Liponyssus; (_c_) to (_h_) after Banks.]
+
+            gg. With eyes.
+
+              h. Anal groove distinct; posterior marginal festoons
+                  present.
+
+                i. Base of the capitulum (fig. 150c) rectangular
+                    dorsally; usually ornate. DERMACENTOR Koch.
+
+                  j. Adults with four longitudinal rows of large
+                      denticles on each half of hypostome; stigmal plate
+                      nearly circular, without dorso-lateral
+                      prolongation, goblets very large, attaining 43u to
+                      115u in diameter; not over 40 per plate, each
+                      plate surrounded by an elevated row of regularly
+                      arranged supporting cells; white rust wanting;
+                      base of capitulum distinctly broader than long,
+                      its postero-lateral angles prolonged slightly, if
+                      at all; coxae T with short spurs; trochanter I with
+                      small dorso-terminal blade. Texas, Arizona, etc.
+                      _D. nitens_
+
+[Illustration: 151. Rhipicephalus bursa, male. After Nuttall and
+Warburton.]
+
+                  jj. Adults with three longitudinal rows of large
+                      denticles on each half of hypostome; goblet cells
+                      always more than 40 per plate; whitish rust
+                      usually present.
+
+                    k. Dorso-lateral prolongation of stigmal plate small
+                        or absent; plates of the adults distinctly
+                        longer than broad; goblet cells large, usually
+                        30u to 85u in diameter, appearing as very coarse
+                        punctations on untreated specimens, but on
+                        specimens treated with caustic potash they
+                        appear very distinct in outline; base of
+                        capitulum distinctly (usually about twice)
+                        broader than long, the postero-lateral angles
+                        distinctly produced caudad; spurs of coxae I
+                        long, lateral spur slightly longer than median;
+                        trochanter I with dorso-terminal spur. _D.
+                        albipictus_, (= _variegatus_), _salmoni_,
+                        _nigrolineatus_.
+
+                    kk. Dorso-lateral prolongation of stigmal plate
+                        distinct.
+
+                      l. Body of plate distinctly longer than broad;
+                          goblet cells of medium size, usually 17.5u to
+                          35u or 40u in diameter, appearing as medium
+                          sized punctuations on untreated specimens, but
+                          on the specimens treated with caustic potash
+                          they appear very distinct in outline, which is
+                          not circular; base of capitulum usually less
+                          than twice as broad as long, the
+                          postero-lateral angles always distinctly
+                          prolonged caudad.
+
+                        m. Trochanter I with distinct dorso-subterminal
+                            retrograde sharp, digitate spur;
+                            postero-lateral angles of capitulum
+                            pronouncedly prolonged caudal, 112u to 160u
+                            long; goblet cells attain 13u to 40u in
+                            diameter; type locality California. D.
+                            OCCIDENTALIS
+
+                        mm. Trochanter I with dorso-terminal blade;
+                            postero-lateral angles of capitulum with
+                            rather short prolongations.
+
+                          n. Stigmal plate small, goblet cells not
+                              exceeding 45 in the male or 100 in the
+                              female; scutum with little rust, coxa I
+                              with short spurs, the inner distinctly
+                              shorter than the outer. _D.
+                              parumapertus-marginatus_
+
+                          nn. Stigmal plate larger; goblet cells over 70
+                              in the male and over 100 in the female;
+                              coxa I with longer spurs, inner slightly
+                              shorter than the outer; scutum with
+                              considerable rust. D. VENUSTUS[F]
+
+                      ll. Goblet cells small, rarely exceeding 17.6u,
+                          occasionally reaching 19u in diameter; on
+                          untreated specimens they appear as very fine
+                          granulations, and on specimens treated with
+                          caustic potash they may be difficult to see,
+                          but their large number can be determined from
+                          the prominent stems of the goblets; surface of
+                          outline of the goblets distinctly circular;
+                          base of the capitulum usually less than twice
+                          as broad as long, the postero-lateral angle
+                          distinctly prolonged caudad; spurs of coxae I
+                          long. _D. reticulatus_ and _electus_ (=
+                          _variabilis_?)
+
+                ii. Base of the capitulum (fig. 151) usually hexagonal
+                    (except in the male of _puchellus_); and usually
+                    inornate.
+
+                  j. No ventral plate or shield in either sex (fig.
+                      153). R. BICORNIS from the United States.
+                      RHIPICENTOR Nuttall
+
+                  jj. Males with a pair of adanal shields, and usually a
+                      pair of accessory adanal shields. Numerous
+                      species, among them _R. sanguineus_ (fig. 154) and
+                      _texanus_, the latter from the United States.
+                      _Rhipicephalus_ Koch
+
+              hh. Anal grooves faint or obsolete; no marginal festoons.
+
+                i. Short palpi; highly chitinized; unfed adults of large
+                    size; coxae conical; male with a median plate
+                    prolonged in two long spines projecting caudad;
+                    segments of leg pair IV greatly swollen (fig. 155,
+                    156). _M. winthemi_ _Margaropus_ Karsch
+
+[Illustration: 152. Monieziella (Histiogaster) emtomophaga-spermatica,
+ventral aspect, male and female. After Trouessart.]
+
+                ii. Very short palpi, ridged dorsally and laterally;
+                    slightly chitinized; unfed adults of smaller size;
+                    coxae I bifid; male with adanal and accessory adanal
+                    shields (fig. 139). B. ANNULATUS. BOOPHILUS Curtis
+
+          ff. Palpi longer than broad (fig. 157).
+
+            g. Male with pair of adanal shields, and two posterior
+                abdominal protrusions capped by chitinized points;
+                festoons present or absent. Several species, among them
+                H. AEGYPTICUM (fig. 140) from the old world. HYALOMMA
+                Koch
+
+            gg. Male without adanal shields but small ventral plaques
+                are occasionally present close to the festoons. Many
+                species, a few from the United States (fig. 157).
+                AMBLYOMMA Koch
+
+
+              h. Coxa I with but one spine; metatarsi (except I) with
+                  two thickened spurs at tips. _A. maculatum_
+
+              hh. Coxa I with two spines; metatarsi without stout spurs
+                  at tips, only slender hairs.
+
+                i. Projections of coxa I blunt and short. Large species
+                    on the gopher tortoise in Florida. _A. tuberculatum_
+
+                ii. Projections of coxa I longer, and at least one of
+                    them sharp pointed; second segment of palpus twice
+                    as long as the third; coxa IV of the male with a
+                    long spine.
+
+                  j. Porose areas nearly circular; shield of both sexes
+                      pale yellowish, with some silvery streaks and
+                      marks, and some reddish spots; shield of female as
+                      broad as long. A. CAJENNENSE (= MIXTUM).
+
+                  jj. Porose areas elongate, shield brown, in the female
+                      with an apical silvery mark, in the male with two
+                      small and two or four other silvery spots; shield
+                      of the female longer than broad (fig 158 e). A.
+                      AMERICANUM.
+
+[Illustration: 153. Rhipicentor bicornis, ventral aspect, male. After
+Nuttall and Warburton.]
+
+    cc. Hypostome small, without teeth, venter without furrows; body
+        often with coriaceous shields, posterior margin of the body
+        never crenulate (i.e. without festoons); no eyes. GAMASOIDEA.
+
+      d. Parasitic on vertebrates; mandibles fitted for piercing; body
+          sometimes constricted. DERMANYSSIDAE.
+
+        e. Anal plate present. DERMANYSSINAE.
+
+          f. Body short; legs stout, hind pair reaching much beyond the
+              tip of the body. On bats. _Pteroptus_ Dufour.
+
+          ff. Body long; hind legs not reaching beyond the tip of the
+              body.
+
+            g. Peritreme on the dorsum, very short; body distinctly
+                  constricted. _Ptilonyssus_ Berl.
+
+            gg. Peritreme on the venter, longer; body not distinctly
+                  constricted.
+
+                h. Mandibles in both sexes chelate. Parasitic on bats,
+                    mice and birds (fig. 150, h). LIPONYSSUS Kol.
+
+                  The species L. (= LEIOGNATHUS) SYLVIARUM frequents the
+                      nests of warblers. An instance is on record of
+                      these mites attacking man, causing a pruritis.
+
+                hh. Mandibles in the male chelate (fig. 158 j), in the
+                    female long, styliform. Parasitic on birds.
+                    DERMANYSSUS Dug. Two species of importance may be
+                    noted, _D. hirundinus_ and D. GALLINAE. The latter
+                    (fig. 51) is a serious pest of poultry, sometimes
+                    attacking man, causing itching and soreness.
+
+        ee. Anal plate absent. In lungs and air passages of some
+            mammals. HALARACHNINAE.
+
+      dd. Free or attached to insects, rarely on vertebrates.
+
+        e. First pair of legs inserted within the same body opening as
+            the oral tube; genital apertures surrounded by the sternum.
+            On insects. UROPODIDAE.
+
+[Illustration: 154. Rhicephalus sanguineus, male. After Nuttall and
+Warburton.]
+
+        ee. First pair of legs inserted at one side of the mouth
+            opening; male genital aperture usually on the anterior
+            margin of the sternal plate. GAMASIDAE.
+
+          This family contains a number of genera, some of which are
+              found upon mammals, though the majority affect only other
+              arthropods. One species, LAELAPS STABULARIS, frequents the
+              bedding in stables, and in one instance at least, has
+              occasioned irritation and itching, in man.
+
+  bb. No distinct spiracle in the stigmal plate on each side of the
+      body.
+
+    c. Body usually coriaceous, with few hairs, with a specialized seta
+        arising from a pore near each posterior corner of the
+        cephalothorax; no eyes; mouth parts and palpi very small;
+        ventral openings of the abdomen large; tarsi without sucker. Not
+        parasitic. ORIBATOIDEA.
+
+    cc. Body softer; without such specialized seta.
+
+      d. Aquatic species. HYDRACHNOIDEA.
+
+      dd. Not aquatic.
+
+        e. Palpi small, three segmented, adhering for some distance to
+            the lip; ventral suckers at genital opening or near anal
+            opening usually present; no eyes; tarsi often end in
+            suckers; beneath the skin on the venter are seen rod-like
+            epimera that support the legs; body often entire. Adults
+            frequently parasitic. SARCOPTOIDEA.
+
+          f. With tracheae; no ventral suckers; legs ending in claws;
+              body divided into cephalothorax and abdomen; the female
+              with a clavate hair between legs I and II. Usually not
+              parasitic on birds and mammals. TARSONEMIDAE
+
+            g. Hind legs of female ending in claw and sucker as in the
+                other pairs. PEDICULOIDINAE
+
+              To this sub-family belongs the genus PEDICULOIDES
+
+              P. ventricosus is described on page 69.
+
+[Illustration: 155. Margaropus winthemi, male. After Nuttall and
+Warburton.]
+
+[Illustration: 156. Margaropus winthemi, capitulum and scutum.
+After Nuttall and Warburton.]
+
+            gg. Hind legs of the female end in long hairs. TARSONEMINAE
+
+              TARSONEMUS INTECTUS Karpelles, normally found upon grain,
+                  is said to attack man in Hungary and Russia. Other
+                  species of the genus affect various plants (c.f. fig.
+                  150, g).
+
+          ff. Without tracheae; no such clavate hair.
+
+            g. Genital suckers usually present; integument usually
+                without fine parallel lines.
+
+              h. Legs short, without clavate hair on tarsi I and II. On
+                  insects. CANESTRINIDAE.
+
+              hh. Legs longer, with a clavate hair on tarsi I and II.
+                  Not normally parasitic except on bees. TYROGLYPHIDAE
+
+                i. Dorsal integument more or less granulate; claws very
+                    weak, almost invisible; some hairs of the body
+                    plainly feathered; ventral apertures large.
+                    GLYCIPHAGUS Her.
+
+                  This genus occurs in the United States. In Europe the
+                      mites have been found feeding on all sorts of
+                      substances. They are known as sugar mites and
+                      cause the disease known as grocer's itch. G.
+                      DOMESTICUS and G. PRUNORUM are old world species
+                      (fig. 150, d).
+
+                ii. Dorsal integument not granulate; claws distinct; no
+                    prominent feathered hairs; ventral aperture small.
+
+                  j. Mandibles not chelate; elongate, and toothed below;
+                      body without long hairs; palpi enlarged at tip and
+                      provided with two divergent bristles. Species feed
+                      on decaying substances. _Histiostoma_ Kram.
+
+                  jj. Mandibles chelate; palpi not enlarged at the tip,
+                      nor with two bristles.
+
+                    k. No clavate hair on the base of tarsi I and II; no
+                        suture between cephalothorax and abdomen. Live
+                        on bees or in their nests. _Trichotarsus_ Can.
+
+                    kk. A clavate or thickened hair at the base of tarsi
+                        I and II.
+
+                      l. The bristle on the penultimate segment of the
+                          legs arises from near the middle; no suture
+                          between the cephalothorax and abdomen. The
+                          species, some of which occur in the United
+                          States, feed on dried fruit, etc.
+                          _Carpoglyphus_ Robin.
+
+                      ll. The bristle on the penultimate segment of the
+                          legs arise from near the tip; a suture between
+                          cephalothorax and abdomen.
+
+                        m. Cephalothorax with four distinct and long
+                            bristles in a transverse row; tarsi I and II
+                            about twice as long as the preceding segment
+                            (fig. 150 f). TYROGLYPHUS Latr.
+
+                          n. Some bristles on tarsi I and II near
+                              middle, distinctly spine-like; the sense
+                              hair about its length from the base of the
+                              segment. Several species in the United
+                              States belong to this group.
+
+                          nn. No spine-like bristles near the middle of
+                              the tarsi; sense hair not its length from
+                              the base of the segment.
+
+                            o. Of the terminal abdominal bristles, only
+                                two are about as long as the abdomen;
+                                leg I of the male greatly thickened and
+                                with a spine at apex of the femur below.
+                                T. FARINAE.
+
+                            oo. Of the terminal abdominal bristles at
+                                least six or more are very long, nearly
+                                as long as the body.
+
+                              p. Bristles of the body distinctly plumose
+                                  or pectinate; tarsi very long. T.
+                                  LONGIOR.
+
+                              pp. Bristles of the body not pectinate.
+
+                                q. In mills, stored foods, grains, etc.
+                                    Third and fourth joints of hind legs
+                                    scarcely twice as long as broad;
+                                    abdominal bristles not unusually
+                                    long; legs I and II of the male not
+                                    unusually stout. T. AMERICANUS.
+
+                                qq. With other characters and habits.
+                                    _T. lintneri_ (fig. 150 f) the
+                                    mushroom mite, and several other
+                                    species.
+
+                        mm. Cephalothorax with but two long distinct
+                            bristles (besides the frontal pair), but
+                            sometimes a very minute intermediate pair;
+                            tarsi I and II unusually short and not twice
+                            as long as the preceding segment.
+
+                          n. Tarsi with some stout spines. RHIZOGLYPHUS
+                              Clap.
+
+                            The species of this genus are vegetable
+                                feeders. Several occur in the United
+                                States. R. PARASITICUS and R.
+                                SPINITARSUS have been recorded from the
+                                old world, attacking human beings who
+                                handle affected plants.
+
+                          nn. Tarsi with only fine hairs. MONIEZIELLA
+                              Berl.
+
+                            The species of this genus, as far as known,
+                                are predaceous or feed on recently
+                                killed animal matter. Several species
+                                occur in the United States. M. (=
+                                HISTIOGASTER) ENTOMOPHAGA (fig. 152)
+                                from the old world has been recorded as
+                                injurious to man.
+
+            gg. Genital suckers absent; integument with fine parallel
+                lines. Parasitic on birds and mammals.
+
+              h. Possessing a specially developed apparatus for clinging
+                  to hairs of mammals. LISTROPHORIDAE.
+
+              hh. Without such apparatus.
+
+                i. Living on the plumage of birds. ANALGESIDAE.
+
+                ii. In the living tissues of birds and mammals.
+
+                  j. Vulva longitudinal. In the skin and cellular
+                      tissues of birds. CYTOLEICHIDAE.
+
+                    This family contains two species, both occurring in
+                        the United States on the common fowl.
+                        _Laminosioptes cysticola_ occurs on the skin and
+                        also bores into the subcutaneous tissue where it
+                        gives rise to a calcareous cyst. _Cytoleichus
+                        nudus_ is most commonly found in the air
+                        passages and air cells.
+
+                  jj. Vulva transverse. In the skin of mammals and
+                      birds. SARCOPTIDAE
+
+                    k. Anal opening on the dorsum.
+
+                      l. Third pair of legs in the male without apical
+                          suckers. On cats and rabbits. NOTOEDRES
+                          Rail.
+
+                        The itch mite of the cat, N. CATI (fig. 61) has
+                            been recorded on man.
+
+                      ll. Third leg in the male with suckers. On bats
+                          _Prosopodectes_ Can.
+
+                    kk. Anal opening below.
+
+                      l. Pedicel of the suckers jointed; mandibles
+                          styliform and serrate near the tip. PSOROPTES
+                          Gerv. P. COMMUNIS OVIS is the cause of sheep
+                          scab.
+
+                      ll. Pedicel of the suckers not jointed; mandibles
+                          chelate.
+
+                        m. No suckers on the legs of the females;
+                            parasitic on birds, including chickens. _C.
+                            mutans_ is itch mite of chickens.
+                            _Cnemidocoptes_ Furst.
+
+                        mm. Suckers at least on legs I and II; parasitic
+                            on mammals.
+
+                          n. Legs very short; in the male the hind pairs
+                              equal in size; body usually short.
+                              SARCOPTES Latr.
+
+                            S. SCABIEI is the itch mite of man (fig.
+                                56).
+
+[Illustration: 157. Amblyomma, female. After Nuttall and Warburton.]
+
+                          nn. Legs more slender; in the male the third
+                              pair is much larger than the fourth; body
+                              more elongate.
+
+                            o. Female with suckers on the fourth pair of
+                                legs. Species do not burrow in the skin,
+                                but produce a scab similar to sheep
+                                scab. They occur in the ox, horse, sheep
+                                and goat. CHORIOPTES Gerv. C. SYMBIOTES
+                                BOVIS of the ox has been recorded a few
+                                times on man.
+
+                            oo. Female without suckers to the fourth
+                                legs.
+
+                              p. Hind part of the male abdomen with two
+                                  lobes. On a few wild animals.
+                                  _Caparinia_ Can.
+
+                              pp. Hind part of the male abdomen without
+                                  lobes. Live in ears of dogs and cats.
+                                  _Otodectes_ Canestr.
+
+                                _O. cynotis_ Hering (fig. 150 e) has
+                                    been taken in the United States.
+
+        ee. Palpi usually of four or five segments, free; rarely with
+            ventral suckers near genital or anal openings; eyes often
+            present; tarsi never end in suckers; body usually divided
+            into cephalothorax and abdomen; rod-like epimera rarely
+            visible; adults rarely parasitic.
+
+          f. Last segment of the palpi never forms a thumb to the
+              preceding segment; palpi simple, or rarely formed to hold
+              prey; body with but few hairs. EUPODOIDEA.
+
+            g. Palpi often geniculate, or else fitted for grasping prey;
+                mandibles large and snout like; cephalothorax with four
+                long bristles above, two in front, two behind; last
+                segment of leg I longer than the preceding segment,
+                often twice as long. BDELLIDAE.
+
+            gg. Palpi never geniculate (fig. 158a), nor fitted for
+                grasping prey: beak small; cephalothorax with bristles
+                in different arrangement; last segment of leg I shorter
+                or but little longer than the preceding joint; eyes when
+                present near posterior border. EUPODIDAE
+
+              Moniez has described a species from Belgium (TYDEUS
+                  MOLESTUS) which attacks man. It is rose colored;
+                  eyeless; its legs are scarcely as long as its body,
+                  the hind femur is not thickened; the mandibles are
+                  small and the anal opening is on the venter. The
+                  female attains a length of about 0.3 mm.
+
+          ff. Last segment of the palpus forms a thumb to the preceding,
+              which ends in a claw (with few exceptions); body often
+              with many hairs (fig. 158 k). TROMBIDOIDEA.
+
+            g. Legs I and II with processes bearing spines; skin with
+                several shields; coxae contiguous. CAECULIDAE.
+
+            gg. Legs I and II without such processes; few if any
+                shields.
+
+              h. Palpi much thickened on the base, moving laterally,
+                  last joint often with two pectinate bristles; no eyes;
+                  legs I ending in several long hairs; adult sometimes
+                  parasitic. CHEYLETIDAE
+
+                CHEYLETUS ERUDITUS, which frequents old books, has once
+                    been found in pus discharged from the ear of man.
+
+              hh. Palpi less thickened, moving vertically; eyes usually
+                  present; leg I not ending in long hairs.
+
+                i. Coxae contiguous, radiate; legs slender, bristly; body
+                    with few hairs; no dorsal groove; tarsi not swollen.
+                    ERYTHRAEIDAE.
+
+                ii. Coxae more or less in two groups; legs less bristly.
+
+[Illustration: 158. (_a_) Tydeus, beak and leg from below; (_b_)
+Cheyletus pyriformis, beak and palpus; (_c_) beak and claw of
+Pediculoides; (_d_) leg of Sarcoptes; (_e_) scutum of female of
+Amblyomma americana; (_f_) leg I and tip of mandible of Histiostoma
+americana; (_g_) Histiogaster malus, mandible and venter; (_h_)
+Aleurobius farinae, palpus and leg I of male; (_i_) Otodectes cynotis,
+tip of abdomen of male, (_j_) beak and anal plate of Dermanyssus
+gallinae female; (_k_) palpus of Allothrombium. (_a_) to (_j_) after
+Banks.]
+
+                  j. Body with fewer, longer hairs; often spinning
+                      threads; no dorsal groove; tarsi never swollen;
+                      mandibles styliform (for piercing). TETRANYCHIDAE
+
+                    The genus TETRANYCHUS may be distinguished from the
+                        other genera occurring in the United States by
+                        the following characters: No scale-like
+                        projections on the front of the cephalothorax;
+                        legs I as long or longer than the body; palp
+                        ends in a distinct thumb; the body is about 1.5
+                        times as long as broad. T. MOLESTISSIMUS Weyenb.
+                        from South America, and T. TELARIUS from Europe
+                        and America ordinarily infesting plants, are
+                        said also to molest man.
+
+                  jj. Body with many fine hairs or short spines; not
+                      spinning threads; often with dorsal groove; tarsi
+                      often swollen.
+
+                    k. Mandibles styliform for piercing. RHYCHOLOPHIDAE.
+
+                    kk. Mandibles chelate, for biting. TROMBIDIDAE
+
+                      The genus TROMBIDIUM has recently been subdivided
+                          by Berlese into a number of smaller ones, of
+                          which some five or six occur in the United
+                          States. The mature mite is not parasitic but
+                          the larvae which are very numerous in certain
+                          localities will cause intense itching,
+                          soreness, and even more serious complications.
+                          They burrow beneath the skin and produce
+                          inflamed spots. They have received the popular
+                          name of "RED BUG." The names LEPTUS AMERICANUS
+                          and L. IRRITANS have been applied to them,
+                          although they are now known to be immature
+                          stages. (Fig. 44.)
+
+
+HEXAPODA (Insecta)
+
+The Thysanura (springtails and bristletails), the Neuropteroids
+(may-flies, stone-flies, dragon-flies, caddis-flies, etc.), Mallophaga
+(bird lice), Physopoda (thrips), Orthoptera (grasshoppers, crickets,
+roaches), are of no special interest from our viewpoint. The remaining
+orders are briefly characterized below.
+
+
+SIPHUNCULATA (page 275)
+
+Mouth parts suctorial; beak fleshy, not jointed; insect wingless;
+parasitic upon mammals. Metamorphosis incomplete. Lice.
+
+
+HEMIPTERA (page 275)
+
+Mouth parts suctorial; beak or the sheath of the beak jointed; in the
+mature state usually with four wings. In external appearance the
+immature insect resembles the adult except that the immature form (i.e.
+nymph) never has wings, the successive instars during the process of
+growth, therefore, are quite similar; and the metamorphosis is thus
+incomplete. To this order belong the true bugs, the plant lice, leaf
+hoppers, frog hoppers, cicadas, etc.
+
+
+LEPIDOPTERA
+
+The adult insect has the body covered with scales and (with the rare
+exception of the females of a few species) with four wings also covered
+with scales. Proboscis, when present, coiled, not segmented, adapted for
+sucking. Metamorphosis complete, i.e. the young which hatches from the
+egg is quite unlike the adult, and after undergoing several molts
+transforms into a quiescent pupa which is frequently enclosed in a
+cocoon from which the adult later emerges. The larvae are known as
+caterpillars. Butterflies and moths.
+
+
+DIPTERA (page 285)
+
+The adult insect is provided with two, usually transparent, wings, the
+second pair of wings of other insects being replaced by a pair of
+halteres or balancers. In a few rare species the wings, or halteres, or
+both, are wanting. The mouth parts, which are not segmented, are adapted
+for sucking. The tarsi are five-segmented. Metamorphosis complete. The
+larvae, which are never provided with jointed legs, are variously known
+as maggots, or grubs, or wrigglers. Flies, midges, mosquitoes.
+
+
+SIPHONAPTERA (page 316)
+
+Mouth parts adapted for sucking; body naked or with bristles and spines;
+prothorax well developed; body compressed; tarsi with five segments;
+wings absent. Metamorphosis complete. The larva is a wormlike creature.
+Fleas.
+
+
+COLEOPTERA
+
+Adult with four wings (rarely wanting), the first pair horny or
+leathery, veinless, forming wing covers which meet in a line along the
+middle of the back. Mouth parts of both immature stages and adults
+adapted for biting and chewing. Metamorphosis complete. The larvae of
+many species are known as grubs. Beetles.
+
+
+HYMENOPTERA
+
+Adult insect with four, usually transparent, wings, wanting in some
+species. Mouth parts adapted for biting and sucking; palpi small; tarsi
+four or five-segmented. Metamorphosis complete. Parasitic four-winged
+flies, ants, bees, and wasps.
+
+
+SIPHUNCULATA AND HEMIPTERA
+
+a. Legs with claws fitted for clinging to hairs; wings wanting;
+    spiracles of the abdomen on the dorsal surface. (= ANOPLURA =
+    PARASITICA) SIPHUNCULATA.
+
+  b. Legs not modified into clinging hooks; tibia and tarsus very long
+      and slender; tibia without thumb-like process; antennae
+      five-segmented. HAEMATOMYZIDAE Endr.
+
+    _Haematomyzus elephantis_ on the elephant.
+
+  bb. Legs modified into clinging hooks; tibia and tarsus usually short
+      and stout; tibia with a thumb-like process; head not anteriorly
+      prolonged, tube-like.
+
+    c. Body depressed; a pair of stigmata on the mesothorax, and
+        abdominal segments three to eight; antennae three to
+        five-segmented.
+
+      d. Eyes large, projecting, distinctly pigmented; pharynx short and
+          broad; fulturae (inner skeleton of head) very strong and broad,
+          with broad arms; proboscis short, scarcely attaining the
+          thorax. PEDICULIDAE
+
+        e. Antennae three-segmented. A few species occurring upon old
+            world monkeys. _Pedicinis_ Gerv.
+
+        ee. Antennae five-segmented.
+
+          f. All legs stout; thumb-like process of the tibia very long
+              and slender, beset with strong spines, fore legs stouter
+              than the others; abdomen elongate, segments without
+              lateral processes; the divided telson with a conical
+              process posteriorly upon the ventral side. PEDICULUS L.
+
+            g. Upon man.
+
+              h. Each abdominal segment dorsally with from one to three
+                  more or less regular transverse rows of small setae;
+                  antenna about as long as the width of the head. Head
+                  louse (fig. 65). P. HUMANUS.
+
+              hh. "No transverse rows of abdominal setae; antenna longer
+                  than the width of the head; species larger." Piaget.
+                  Body louse of man. P. CORPORIS.
+
+            gg. Upon apes and other mammals. _P. pusitatus_ (?).
+
+          ff. Fore legs delicate, with very long and slender claws;
+              other legs very stout with short and stout claws;
+              thumb-like process of the tibia short and stout; abdomen
+              very short and broad; segment one to five closely crowded,
+              thus the stigmata of segments three to five apparently
+              lying in one segment; segments five to eight with lateral
+              processes; telson without lateral conical appendages (fig.
+              69). Crab louse of man. PHTHIRUS PUBIS.
+
+      dd. Eyes indistinct or wanting; pharynx long and slender, fulturae
+          very slender and closely applied to the pharynx; proboscis
+          very long. Several genera found upon various mammals.
+          HAEMATOPINIDAE.
+
+    cc. Body swollen; meso- and metathorax, and abdominal segments two
+        to eight each with a pair of stigmata; eyes wanting; antennae
+        four or five-segmented; body covered with stout spines. Three
+        genera found upon marine mammals. ECHINOPHTHIRIIDAE
+
+aa. Legs fitted for walking or jumping; spiracles of abdomen usually
+    ventral; beak segmented.
+
+  b. Apex of head usually directed anteriorly; beak arising from its
+      apex; sides of the face remote from the front coxae; first pair of
+      wings when present thickened at base, with thinner margins.
+      HETEROPTERA
+
+[Illustration: 159. Taxonomic details of Hemiptera-Heteroptera. (_a_)
+Dorsal aspect; (_b_) seta from bedbug; (_c_) wing of Heteropteron; (_d_)
+leg; (_e_) wing of Sinea.]
+
+    c. Front tarsi of one segment, spade-form (palaeformes); beak short,
+        at most two-segmented; intermediate legs long, slender;
+        posterior pair adapted for swimming. CORIXIDAE
+
+    cc. Front tarsi rarely one-segmented, never spade-form; beak free,
+        at least three-segmented.
+
+      d. Pulvilli wanting.
+
+        e. Hemelytra usually with a distinct clavus (fig. 159), clavus
+            always ends behind the apex of the scutellum, forming the
+            commissure. (Species having the wings much reduced or
+            wanting should be sought for in both sections.)
+
+          f. Antennae very short; meso- and metasternum composite; eyes
+              always present.
+
+            g. Ocelli present; beak four-segmented. OCHTERIDAE and
+                NERTHRIDAE.
+
+            gg. Ocelli wanting; antennae more or less hidden in a groove.
+
+              h. Anterior coxae inserted at or near anterior margin of
+                  the prosternum; front legs raptorial; beak
+                  three-segmented BELOSTOMIDAE (with swimming legs),
+                  NEPIDAE, NAUCORIDAE.
+
+                i. Metasternum without a median longitudinal keel;
+                    antennae always four-segmented.
+
+                  j. Beak short, robust, conical; the hairy fleck on the
+                      corium elongate, large, lying in the middle
+                      between the inner angle of the membrane and the
+                      outer vein parallel to the membrane margin;
+                      membrane margin S-shaped.
+
+                    k. The thick fore femur with a relatively deep
+                        longitudinal furrow to receive the tibia.
+                        Several American species (fig. 19f.). BELOSTOMA
+                        (= Lethocerus Mayer)
+
+                    kk. The less thickened fore femur without such a
+                        furrow. B. GRISEUS. BENACUS Stal.
+
+                  jj. Beak slender, cylindrical; the hairy spot on the
+                      corium rounded lying next to the inner angle of
+                      the membrane.
+
+                    k. Membrane large, furrow of the embolium broadened.
+                        _Z. aurantiacum_, _fluminea_, etc. _Zaitha_
+
+                    kk. Membrane very short; furrow of embolium not
+                        broadened. Western genus. _Pedinocoris_
+
+              ii. Metasternum with a long median longitudinal keel.
+                  Southwestern forms. _Abedus ovatus_ and _Deniostoma
+                  dilatato_
+
+            hh. Anterior coxae inserted at the posterior margin of the
+                prosternum; legs natatorial. Back swimmers (fig. 19 b.).
+                NOTONECTIDAE
+
+              i. Apices of the hemelytra entire; the three pairs of legs
+                  similar in shape; beak three-segmented; abdomen not
+                  keeled or hairy. _Plea_ Leach
+
+              ii. Apices of hemelytra notched; legs dissimilar; beak
+                  four-segmented; abdomen keeled and hairy.
+
+                j. Hemelytra usually much longer than the abdomen;
+                    fourth segment of the antenna longer than the third
+                    segment; hind tarsi with claws. _Bueno_ Kirk.
+
+                jj. Hemelytra but little longer than the abdomen; fourth
+                    segment of the antenna shorter than the third
+                    segment; hind tarsi without claws (fig. 19b).
+                    NOTONECTA L.
+
+          ff. Antennae longer than the head; or if shorter, then the eyes
+              and ocelli absent.
+
+            g. Eyes, ocelli, and scutellum wanting; beak
+                three-segmented; head short; hemelytra always short;
+                membrane wanting. Insects parasitic on bats. POLYCTENIDAE
+
+            gg. Eyes present.
+
+              h. First two antennal segments very short, last two long,
+                  pilose, third thickened at the base; ocelli present,
+                  veins of the hemelytra forming cells. DIPSOCORIDAE (=
+                  CERATOCOMBIDAE) including SCHIZOPTERIDAE.
+
+              hh. Third segment of the antenna not thickened at the
+                  base, second as long or longer than the third, rarely
+                  shorter.
+
+                i. Posterior coxae hinged (cardinate), if rarely
+                    rotating, the cuneus is severed, the membrane is one
+                    or two-celled, and the meso- and metasternum are
+                    composite.
+
+                  j. Ocelli absent, clypeus dilated toward the apex;
+                      hemelytra always short, membrane wanting. Species
+                      parasitic. Bed bugs, etc. CIMICIDAE
+
+                    k. Beak short, reaching to about the anterior coxae;
+                        scutellum acuminate at the apex; lateral margin
+                        of the elytra but little reflexed, apical margin
+                        more or less rounded; intermediate and posterior
+                        coxae very remote.
+
+                      l. Body covered with short hairs, only the sides
+                          of the pronotum and the hemelytra fringed with
+                          longer hairs; antennae with the third and
+                          fourth segments very much more slender than
+                          the first and second; pronotum with the
+                          anterior margin very _deeply sinuate_. CIMEX
+                          L.
+
+                        m. Sides of the pronotum widely dilated, broader
+                            than the breadth of one eye, and densely
+                            fringed with backward curved hairs; apical
+                            margin of the hemelytra nearly straight,
+                            rounded toward the interior or exterior
+                            angles.
+
+                          n. Body covered with very short hairs; second
+                              segment of the antenna shorter than the
+                              third; sides of the pronotum feebly
+                              reflexed, fringed with shorter hairs than
+                              the breadth of one eye; hemelytra with the
+                              commissural (inner) margin rounded and
+                              shorter than the scutellum, apical margin
+                              rounded towards the interior angle. The
+                              common bed bug (fig. 19h). C. LECTULARIUS
+                              Linn
+
+                          nn. Body covered with longer hairs; second and
+                              third segments of the antenna of equal
+                              length; side of the pronotum narrowly, but
+                              distinctly, reflexed, fringed with longer
+                              hairs than the breadth of one eye;
+                              hemelytra with the commissural margin
+                              straight and longer than the scutellum,
+                              apical margin rounded towards the exterior
+                              angle. Species found on bats in various
+                              parts of the United States. _C.
+                              pillosellus_ Hov.
+
+                        mm. Sides of the pronotum neither dilated, nor
+                            reflexed, fringed with less dense and nearly
+                            straight hairs; hemelytra with the apical
+                            margin distinctly rounded. Parasitic on man,
+                            birds and bats. Occurs in the old world,
+                            Brazil and the West Indies. C. HEMIPTERUS
+                            Fabr. (= rotundatus)
+
+                      ll. Body clothed with rather longer silky hairs;
+                          third and fourth segments of the antenna
+                          somewhat more slender than the first and
+                          second; anterior margin of the pronotum _very
+                          slightly sinuate_ or nearly straight in the
+                          middle, produced at the lateral angles. This
+                          is the species which in American collections
+                          is known as _C. hirundinis_, the latter being
+                          an old world form. It is found in swallows
+                          nests. O. VICARIUS. OECIACUS Stal
+
+                    kk. Beak long, reaching to the posterior coxae;
+                        scutellum rounded at the apex; lateral margins
+                        of the elytra strongly reflexed, apical margin
+                        slightly sinuate toward the middle; intermediate
+                        and posterior coxae sub-contiguous. This species
+                        infests poultry in southwest United States and
+                        in Mexico. H. INODORUS. HAEMATOSIPHON Champ.
+
+[Illustration: 160. Pselliopsis (Milyas) cinctus (x2). After C. V.
+Riley.]
+
+                  jj. Ocelli present, if rarely absent in the female,
+                      then the tarsus has two segments; or if with three
+                      tarsal segments, the wing membrane with one or two
+                      cells.
+
+                    k. Beak four-segmented, or with two-segmented tarsi.
+                        ISOMETOPIDAE, MICROPHYSIDAE, and some
+                        CAPSIDAE.
+
+                    kk. Beak three-segmented.
+
+                      l. Hemelytra with embolium; head horizontal, more
+                          or less conical; membrane with one to four
+                          veins, rarely wanting. ANTHOCORIDAE
+
+                        Several species of this family affecting man
+                            have been noted, ANTHOCORIS KINGI and
+                            CONGOLENSE, from Africa and LYCTOCORIS
+                            CAMPESTRIS from various parts of the world.
+                            LYCTOCORIS FITCHII Reuter (fig. 19 j), later
+                            considered by Reuter as a variety of L.
+                            CAMPESTRIS, occurs in the United States.
+
+                      ll. Hemelytra without embolium. Superfamily
+                          ACANTHIOIDEA (= SALDAE Fieber and LEPTOPODAE
+                          Fieber)
+
+                ii. Posterior coxae rotating.
+
+                  j. Claws preapical; aquatic forms. GERRIDAE and
+                      VELIADAE
+
+                  jj. Claws apical.
+
+                    k. Prosternum without stridulatory sulcus (notch for
+                        beak).
+
+                      l. Tarsus with three segments; membrane with two
+                          or three longitudinal cells from which veins
+                          radiate; rarely with free longitudinal veins
+                          (Arachnocoris) or veins nearly obsolete
+                          (Arbela); clavus and corium coriaceous; ocelli
+                          rarely absent. NABIDAE
+
+                        REDUVIOLUS (= CORISCUS) SUBCOLEOPTRATUS (fig. 19
+                            g), a species belonging to this family,
+                            occurring in the United States, has been
+                            accused of biting man. This insect is flat,
+                            of a jet black color, bordered with yellow
+                            on the sides of the abdomen, and with
+                            yellowish legs. It is predaceous, feeding on
+                            other insects.
+
+                      ll. With other combinations of characters.
+                          HYDROMETRIDAE, HENICOCEPHALIDAE,
+                          NAEOGEIDAE, MESOVELIADAE, JOPPEICIDAE
+
+                    kk. Prosternum with stridulatory sulcus (notch for
+                        beak); with three segments, short, strong.
+
+                      l. Antennae filiform or sometimes more slender
+                          apically, geniculate; wing membrane with two
+                          or three large basal cells; scutellum small or
+                          moderate/ REDUVIIDAE
+
+                        For a key to the genera and species see next
+                            page.
+
+                      ll. Last antennal segment clavate or fusiform; win
+                          membrane with the veins often forked and
+                          anastomosing; scutellum large; tarsi each with
+                          two segments; fore legs strong. (= PHYMATIDAE)
+                          MACROCEPHALIDAE
+
+        ee. Clavus noticeably narrowed towards the apex, never extending
+            beyond the scutellum, the two not meeting to form a
+            commissure; head horizontal, much prolonged between the
+            antennae, on each side with an antennal tubercle, sometimes
+            acute; ocelli absent; meso- and metasternum simple; tarsi
+            each with two segments; body flattened (fig. 19c). ARADIDAE,
+            including DYSODIIDAE.
+
+      dd. Pulvilli present (absent in one Australian family
+          THAUMATOCORIDAE in which case there is a membranous
+          appendage at the tip of the tibia). CAPSIDAE (=
+          MIRIDAE),[G] _Eotrechus_ (in family GERRIDAE),
+          NAEOGAIDAE, TINGITIDAE, PIESMIDAE, MYODOCHIDAE,
+          CORIZIDAE, COREIDAE, ALYDIDAE, PENTATOMIDAE,
+          SCUTELLERIDAE, etc.
+
+  bb. Apex of head directed ventrally, beak arising from the hinder part
+      of the lower side of the head; sides of face contiguous to the
+      front coxae; first pair of wings, when present, of uniform
+      thickness. Cicadas, scale insects, plant lice (Aphids),
+      spittle-insects, leaf hoppers, etc. HOMOPTERA
+
+
+REDUVIIDAE OF THE UNITED STATES
+
+(Adapted from a key given by Fracker).
+
+a. Ocelli none; wings and hemelytra always present in the adults; no
+    discoidal areole in the corium near the apex of the clavus.
+    _Orthometrops decorata_, _Oncerotrachelus acuminatus_, etc.,
+    Pennsylvania and south. _Sarcinae_
+
+aa. Ocelli present in the winged individuals; anterior coxae not as long
+    as the femora.
+
+  b. Hemelytra without a quadrangular or discoidal areole in the corium
+      near the apex of the clavus.
+
+    c. Ocelli not farther cephalad than the caudal margins of the eyes;
+        segment two of the antenna single.
+
+      d. Thorax usually constricted caudad of the middle; anterior coxae
+          externally flat or concave. PIRATINAE
+
+        e. Middle tibiae without spongy fossa, head long, no lateral
+            tubercle on neck. _S. stria_, Carolina, Ill., Cal.
+            _Sirthenia_ Spinola
+
+        ee. Middle tibiae with spongy fossa; fore tibiae convex above;
+            neck with a small tubercle on each side.
+
+          f. Apical portion of anterior tibiae angularly dilated beneath,
+              the spongy fossa being preceded by a small prominence.
+              MELANOLESTES Stal
+
+            g. Black, with piceous legs and antennae. N. E. States (fig.
+                19a) M. PICIPES
+
+            gg. Sides, and sometimes the whole dorsal surface of the
+                abdomen red. Ill., and southward. M. ABDOMINALIS
+
+          ff. Tibiae not dilated as in "f"; spongy fossa elongate;
+              metapleural sulci close to the margin. R. BIGUTTATUS (fig.
+              22). South RASAHUS A. and S.
+
+      dd. Thorax constricted in the middle or cephalad of the middle;
+          anterior tarsi each three-segmented.
+
+        e. Apex of the scutellum narrow, without spines or with a single
+            spine REDUVIINAE
+
+          f. Antennae inserted in the lateral or dorso-lateral margins of
+              the head; antenniferous tubercles slightly projecting from
+              the sides of the head; head produced strongly cephalad;
+              ocelli at least as far apart as the eyes.
+
+            g. Antennae inserted very near the apex of the head; segments
+                one and three of the beak short, segment two nearly four
+                times as long as segment one. R. PROLIXUS. W. I.
+                RHODNIUS Stal
+
+            gg. Antennae inserted remote from the vertex of the head.
+
+              h. Body slightly hairy; pronotum distinctly constricted;
+                  angles distinct; anterior lobe four-tuberculate, with
+                  the middle tubercles large and conical. _M.
+                  phyllosoma_, large species from the southwest.
+                  _Meccus_ Stal
+
+              hh. Body smooth, margin of the pronotum sinuous, scarcely
+                  constricted; anterior lobe lined with little
+                  tubercles. CONORHINUS Lap.
+
+                i. Surface of the pronotum and prosternum more or less
+                    granular.
+
+                  j. Eyes small, head black; body very narrow, a fifth
+                      as wide as long; beak reaches the middle of the
+                      prosternum. California. C. PROTRACTUS
+
+                  jj. Eyes large, head fuscous; body at least a fourth
+                      as wide as long. Southern species. _C.
+                      rubrofasciatus_
+
+                ii. Pronotum and prosternum destitute of granules.
+
+                  j. Border of abdomen entirely black except for a
+                      narrow yellowish spot at the apex of one segment.
+                      Texas. _C. gerstaeckeri_
+
+                  jj. Border of abdomen otherwise marked.
+
+                    k. Beak slender, joints one and two slightly pilose,
+                        two more than twice as long as one; tubercles at
+                        the apical angles of the pronotum slightly
+                        acute, conical. Md. to Ill. and south. The
+                        masked bed bug hunter (fig. 71). C. SANGUISUGUS
+
+                    kk. Beak entirely pilose, joint two a third longer
+                        than joint one; joint one much longer than
+                        three; tubercles at the apical angles of
+                        pronotum slightly elevated, obtuse. Ga., Ill.,
+                        Tex., Cal. _C. variegatus_
+
+          ff. Antenna inserted on top of the head between margins, close
+              to the eyes; antenniferous tubercles not projecting from
+              the side of the head.
+
+            g. Anterior lobe of the pronotum with a bispinous or
+                bituberculate disc; femora unarmed. _S. arizonica_, _S.
+                bicolor_. Southwestern species. _Spiniger_ Burm.
+
+            gg. Disc of pronotum unarmed; apex of scutellum produced
+                into a spine; ocelli close to the eyes; eyes large and
+                close together. REDUVIUS Lamarck
+
+              h. Color piceous. Widely distributed in the United States.
+                  (Fig. 20). R. PERSONATUS
+
+              hh. More or less testaceous in color. Southwestern states.
+                  R. SENILIS
+
+        ee. Apex of scutellum broad, with two or three spines.
+            ECTRICHODIINAE
+
+          f. First segment of the antenna about as long as the head. _E.
+              cruciata_ Pa. and south; _E. cinctiventris_, Tex. and Mex.
+              _Ectrichodia_ L. et S.
+
+          ff. First segment of the antennae short. _P. aeneo-nitens_.
+              South. _Pothea_ A. et S.
+
+    cc. Ocelli cephalad of the hind margins of the eyes; first segment
+        of the antennae stout, second segment divided into many smaller
+        segments. South and west. _Homalocoris maculicollis_, and
+        _Hammatocerus purcis_. HAMMATOCERINAE
+
+  bb. Hemelytra with a quadrangular or discoidal areole in the corium
+      near the apex of the clavus (fig. 159e).
+
+    c. Anal areole of the membrane not extending as far proximad as the
+        costal areole; basal segment of the antenna thickened, porrect;
+        the other segments slender, folding back beneath the head and
+        the first segment STENOPODINAE
+
+      d. Head armed with a ramous or furcate spine below each side,
+          caudad of the eyes.
+
+        e. First segment of the antenna thickened, apex produced in a
+            spine beyond the insertion of the second segment. Species
+            from Va., Ill. and south. _Pnirontis_ Stal.
+
+        ee. First segment of the antenna not produced beyond the
+            insertion of the second segment. _Pygolampis_, N. E. states
+            and south; _Gnathobleda_, S. W. and Mex.
+
+      dd. Head unarmed below or armed with a simple spine; rarely with a
+          subfurcate spine at the side of the base. Carolina, Missouri
+          and south. _Stenopoda_, _Schumannia_, _Diaditus_, _Narvesus_,
+          _Oncocephalus_
+
+    cc. Anal areole of membrane extending farther proximad than the
+        costal areole.
+
+      d. Ocelli farther apart than the eyes. _A. crassipes_, widely
+          distributed in the United States; other species occur in the
+          southwest. _Apiomerus_ Hahn.
+
+      dd. Ocelli not so far apart as the eyes. ZELINAE
+
+        e. Sides of mesosternum without a tubercle or fold in front.
+
+          f. Fore femur as long as or longer than the hind femur; first
+              segment of the beak much shorter than the second. _Z.
+              audax_, in the north eastern states; other species south
+              and west. _Zelus_ Fabr.
+
+          ff. Fore femur shorter than the hind femur, rarely of equal
+              length, in this case the first segment of the beak as long
+              or longer than the second.
+
+            g. First segment of the beak shorter than the second; fore
+                femur a little shorter than the hind femur; the first
+                segment of the beak distinctly longer than the head
+                before the eyes. _P. cinctus_ a widely distributed
+                species (fig. 160). _P. punctipes_, _P. spinicollis_,
+                Cal., Mex. (= _Milyas_) _Pselliopus_ Berg.
+
+            gg. First segment of the beak as long or longer than the
+                second.
+
+              h. Pronotum armed with spines on the disc.
+
+                i. Juga distinctly prominent at the apex and often acute
+                    or subacute; fore femur distinctly thickened;
+                    hemelytra usually not reaching the apex of the
+                    abdomen. _Fitchia aptera_, N. Y., south and west;
+                    _F. spinosula_, South; _Rocconata annulicornis_,
+                    Texas, etc.
+
+                ii. Juga when prominent, obtuse at apex; eyes full width
+                    of the head; fore femur not thickened; pronotum with
+                    four spines on posterior lobe. _R. taurus_, Pa.,
+                    south and west. _Repipta_ Stal.
+
+              hh. Pronotum unarmed on the disc.
+
+                i. Spines on each apical angle of the penultimate
+                    abdominal segment. _A. cinereus_, Pa., and south.
+                    _Atrachelus_ A. et S.
+
+                ii. Apical angle of the penultimate abdominal segment
+                    unarmed. _Fitchia_ (in part); _Castolus ferox_,
+                    Arizona.
+
+        ee. Sides of the mesosternum with a tubercle or fold in front at
+            the hind angles of the prosternum; first segment of the beak
+            longer than the part of the head cephalad of the eyes.
+
+          f. Fore femur thickened, densely granulated; hind femur
+              unarmed.
+
+[Illustration: 161. Taxonomic details of Diptera. (_a_) Ventral aspect
+of abdomen of Cynomyia; (_b_) antenna of Tabanus; (_c_) ventral aspect
+of abdomen of Chortophila; (_d_) ventral aspect of abdomen of Stomoxys;
+(_e_) claw of Aedes (Culex) sylvestris, male; (_f_) claw of Hippoboscid;
+(_g_) foot of dipterous insect showing empodium developed pulvilliform;
+(_h_) hind tarsal segment of Simulium vittatum, female; (_i_) foot of
+dipterous insect showing bristle-like empodium.]
+
+            g. Fore tibiae each with three long spines on the ventral
+                side. _S. diadema_ (fig. 159e), a widely distributed
+                species; and several southwestern species. _Sinea_ A. et
+                S.
+
+            gg. Fore tibiae unarmed. _A. multispinosa_, widely
+                distributed; _A. tabida_, Cal. _Acholla_ Stal.
+
+          ff. Fore femur unarmed, rarely a little thickened, a little
+              granulated.
+
+            g. Pronotum produced caudad over the scutellum, with a high
+                mesal tuberculate ridge (fig. 19e). A. CRISTATUS. N. Y.
+                to Cal. and south. ARILUS Hahn.
+
+            gg. Caudal lobe of the pronotum six sided, neither elevated
+                nor produced caudad. _H. americanus_, Southwest; also
+                several W. I. and Mexican genera. HARPACTOR Lap.
+
+
+DIPTERA (Mosquitoes, Midges, Flies)
+
+a. Integument leathery, abdominal segments indistinct; wings often
+    wanting; parasitic forms. PUPIPARA
+
+  b. Head folding back on the dorsum of the thorax; wingless flies
+      parasitic on bats. Genus _Nycteribia_. NYCTERIBIIDAE
+
+  bb. Head not folding back upon the dorsum of the thorax; flies either
+      winged or wingless; parasitic on birds and on bats and other
+      mammals.
+
+    c. Antennae reduced, wings when present, with distinct parallel veins
+        and outer crossveins; claws simple; palpi leaf-like, projecting
+        in front of the head. Flies chiefly found on bats. Several
+        genera occur in North America. STREBLIDAE
+
+[Illustration: 162. Hippobosca equina, x4. After Osborn.]
+
+    cc. Antennae more elongate, segments more or less distinctly
+        separated; head sunk into an emargination of the thorax; wings
+        when present with the veins crowded toward the anterior margin;
+        palpi not leaf-like. HIPPOBOSCIDAE
+
+      d. Wings absent or reduced and not adapted for flight.
+
+        e. Wings and halteres (balancers) absent. _M. ovinus_, the sheep
+            tick. _Melophagus_ Latr.
+
+        ee. Wing reduced (or cast off), halteres present.
+
+          f. Claw bidentate; ocelli present. On deer after the wings are
+              cast off. _L. depressa_. _Lipoptena_ Nitsch
+
+          ff. Claw tridentate (fig. 161 f). On _Macropis_. _B.
+              femorata._ _Brachypteromyia_ Will.
+
+      dd. Wings present and adapted for flight.
+
+        e. Claws bidentate.
+
+          f. Ocelli present; head flat; wings frequently cast off. On
+              birds before casting of the wing. _Lipoptena_ Nitsch.
+
+          ff. Ocelli absent; head round; wings present. The horse tick
+              H. EQUINA may attack man (fig. 162). HIPPOBOSCA L.
+
+        ee. Claws tridentate (fig. 161 f.).
+
+          f. Anal cell closed at apical margin by the anal crossvein.
+
+            g. Ocelli absent. _Stilbometopa_ Coq.
+
+            gg. Ocelli present.
+
+              h. R_{4+5} does not form an angle at the crossvein. On
+                  birds. There is a record of one species of this genus
+                  attacking man. ORNITHOMYIA Latr.
+
+              hh. R_{4+5} makes an angle at the crossvein. _O.
+                  confluens_. _Ornithoica_ Rdi.
+
+          ff. Anal cell not closed by an anal crossvein. _Lynchia_,
+              _Pseudolfersia_, and _Olfersia_ are chiefly bird
+              parasites. The first mentioned genus is said to be the
+              intermediate host of _Haemoproteus columbae_.
+
+aa. Abdominal segments chitinous; not parasitic in the adult stage.
+
+  b. Antennae with six or more segments and empodium not developed
+      pulvilliform; palpi often with four segments.
+
+    c. Ocelli present. BLEPHAROCERIDAE, RHYPHIDAE, BIBIONIDAE,
+        MYCETOPHILIDAE, besides some isolated genera of other families.
+
+    cc. Ocelli absent.
+
+      d. Dorsum of the thorax with a V-shaped suture; wings usually with
+          numerous veins; legs often very long and slender. Crane flies.
+          TIPULIDAE
+
+      dd. Dorsum of the thorax without a V-shaped suture.
+
+        e. Not more than four longitudinal veins ending in the wing
+            margin; wing usually hairy: antennae slender; coxae not
+            long; tibiae: without spurs, legs long and slender. Small,
+            delicate flies often called Gall gnats. CECIDOMYIIDAE.
+
+        ee. More than four longitudinal veins ending in the wing margin.
+
+          f. The costal vein is not produced beyond the tip of the wing;
+              radius with not more than three branches.
+
+            g. Antennae short, composed of ten or eleven closely united
+                segments; legs stout; body stout; abdomen oval; anterior
+                veins stout, posterior ones weak (fig. 163 b); eyes of
+                the male contiguous over the antennae. Black flies,
+                buffalo flies, turkey gnats. Many North American
+                species, several of them notorious for their blood
+                sucking propensities. SIMULIIDAE
+
+              h. Second joint of the hind tarsus with basal scale-like
+                  process and dorsal excision (fig. 161 h); radial
+                  sector not forked; no small cell at the base of the
+                  wing. _S. forbesi_, _jenningsi_, _johannseni_,
+                  _meridionale_, _piscicidium_, VENUSTUM, VITTATUM, etc.
+                  Widely distributed species (= EUSIMULIUM) SIMULIUM
+                  Latr.
+
+              hh. No basal scale-like process on the second joint of the
+                  hind tarsus; radial sector usually forked (fig. 163
+                  b).
+
+                i. Face broad, small basal cell of the wing present. _P.
+                    fulvum_, HIRTIPES, _mutatum_, PECUARUM, _pleurale_.
+                    PROSIMULIUM Roub.
+
+                ii. Face linear; small basal cell of the wing absent.
+                    One species, _P. furcatum_, from California.
+                    _Parasimulium_ Malloch
+
+            gg. Flies of a different structure.
+
+              h. Antennae composed of apparently two segments and a
+                  terminal arista formed of a number of closely united
+                  segments. Rare flies with aquatic larvae.
+                  ORPHNEPHILIDAE
+
+              hh. Antennae of six to fifteen segments, those of the male
+                  usually plumose; legs frequently slender and wings
+                  narrow. CHIRONOMIDAE
+
+                i. Media forked (except in the European genus
+                    _Brachypogon_); thorax without longitudinal fissure
+                    and not produced over the head (except in four
+                    exotic genera); antennae usually fourteen-jointed in
+                    both sexes; fore tibia with a simple comb of setulae,
+                    hind tibia with two unequal combs, middle tibia
+                    without comb. CERATOPOGONINAE
+
+                  j. Thorax produced cap-like over the head, wing narrow
+                      and very long. _Jenkinsia_, _Macroptilum_ and
+                      _Calyptopogon_, eastern hemisphere;
+                      _Paryphoconus_, Brazil.
+
+                  jj. Thorax not produced over the head.
+
+                    k. Eyes pubescent, empodium well developed, or if
+                        short then R_{2+3} distinct and crossvein-like
+                        or the branches of R coalescent; r-m crossvein
+                        present; fore femora not thickened; wing either
+                        with appressed hairs or with microscopic erect
+                        setulae. _Dasyhelea_ Kieff.
+
+                    kk. Eyes bare, or otherwise differing from the
+                        foregoing.
+
+                      l. Empodium well developed, nearly as long as the
+                          claws and with long hairs at the base; femora
+                          and fifth tarsal segments unarmed, i.e.
+                          without spines or stout setae; fourth tarsal
+                          segment cylindrical.
+
+                        m. Wing with erect and microscopic setulae.
+                            Widely distributed. (= Atrichopogon)
+                            _Ceratopogon_ Meig.
+
+                        mm. Wing with long and depressed hairs. Widely
+                            distributed. _Forcipomyia_
+
+                          n. Hind metatarsus shorter or not longer than
+                              the following (i.e. the second tarsal)
+                              segment. Subgenus _Prohelea_ Kieff
+
+                          nn. Hind metatarsus longer than the following
+                              segment. Subgenus _Forcipomyia_ Meig.
+
+                      ll. Empodium short, scarcely reaching the middle
+                          of the claws, or vestigial.
+
+                        m. R-m crossvein wanting.
+
+                          n. Palpi four segmented; inferior fork of the
+                              media obliterated at the base. Australia.
+                              _Leptoconops_ Skuse
+
+                          nn. Palpi three-segmented.
+
+                            o. Legs spinulose, tarsal claws of the
+                                female with a basal tooth or strong
+                                bristle, those of the male unequal, the
+                                anterior with a long sinuous tooth, the
+                                posterior with a short arcuate tooth.
+                                Italy. MYCTEROTYPUS Noe
+
+                            oo. Legs unarmed; no crossvein between the
+                                branches of the radius (fig. 163e). New
+                                Mexico. TERSESTHES Townsend
+
+                        mm. R-m crossvein present.
+
+                          n. Fore femora very much swollen, armed with
+                              spines below, fore tibia arcuate and
+                              applied closely to the inferior margin of
+                              the femur.
+
+                            o. R_{2+3} present, therefore cell R_1 and
+                                R_2 both present; wing usually fasciate.
+                                United States _Heteromyia_ Say.
+
+                            oo. R_{2+3} not distinct from R_{4+5}, hence
+                                cell R_3 obliterated. South America
+                                _Pachyleptus_ Arrib. (Walker)
+
+                          nn. Fore femur not distinctly swollen.
+
+                            o. R_{2+3} present therefore cells R_1 and
+                                R_3 both present, or if not, then the
+                                branches of the radius more or less
+                                coalescent, obliterating the cells.
+
+                              p. At least the tip of the wing with erect
+                                  setulae; tip of R_{4+5} scarcely
+                                  attaining the middle of the wing,
+                                  empodium rather indistinct, not
+                                  reaching the middle of the claws, the
+                                  claws not toothed, equal, with long
+                                  basal bristle; legs without stout
+                                  setae. Widely distributed. CULICOIDES
+                                  Latr.
+
+                                HAEMATOMYIDIUM and OECACTA are probable
+                                    synonyms of this.
+
+                              pp. Wings bare, if rarely with hair, then
+                                  the radius reaches beyond two-thirds
+                                  the length of the wing, or the femur
+                                  or fifth tarsal segment with stout
+                                  black spines.
+
+                                q. Media unbranched. Europe.
+                                    _Brachypogon_ Kieff
+
+                                qq. Media branched.
+
+                                  r. Hind femur much swollen and spined.
+                                      America and Europe. _Serromyia_
+                                      Meg.
+
+                                  rr. Hind femur not distinctly swollen.
+
+                                    s. Cell R_1 not longer than high;
+                                        fork of the media distad of the
+                                        crossvein; wing with microscopic
+                                        setulae. _Stilobezzia_ Kieff
+
+                                    ss. Cell R_1 elongate.
+
+                                      t. Femora unarmed. Widely
+                                          distributed. (= Sphaeromias
+                                          Kieff. 1913 not Curtis?).
+                                          JOHANNSENIELLA Will.
+
+                                      tt. Femora, at least in part, with
+                                          strong black spines. Widely
+                                          distributed. _Palpomyia_
+                                          Megerle
+
+                            oo. R_{2+3} coalescent with R_{4+5} hence
+                                cell R_3 is obliterated.
+
+                              p. In the female the lower branch of the
+                                  media with an elbow near its base
+                                  projecting proximad, the petiole of
+                                  the media coalescent with the basal
+                                  section of the radius, wing long and
+                                  narrow, radial sector ending near the
+                                  tip of the wing; venation of the male
+                                  as in _Bezzia_; front concave. United
+                                  States. _Stenoxenus_ Coq.
+
+                              pp. Venation otherwise, front not concave.
+
+                                q. Subcosta and R_1 more or less
+                                    coalescent with the costa; wing
+                                    pointed at the apex, much longer
+                                    than the body; antennae fourteen
+                                    segmented, not plumose. India.
+                                    _Haasiella_ Kieff.
+
+                                qq. Subcosta and radius distinct from
+                                    the costa.
+
+                                  r. Abdomen petiolate. _Dibezzia_
+                                      Kieff.
+
+                                  rr. Abdomen not petiolate.
+
+                                    s. Head semi-globose; hind tarsi
+                                        unusually elongate in the
+                                        female; antennae of the male not
+                                        plumose. Europe. _Macropeza_
+                                        Meigen.
+
+                                    ss. Head not globose, more or less
+                                        flattened in front; antennae of
+                                        the male plumose. Widely
+                                        distributed. _Bezzia_ Kieff.
+
+                                      t. Fore femora, at least, armed
+                                          with stout spines below.
+                                          Subgenus _Bezzia_ Kieff.
+
+                                      tt. Femora unarmed. Subgenus
+                                          _Probezzia_ Kieff.
+
+                ii. Media of the wing simple, and otherwise not as in
+                    "i". To this group belong numerous Chironomid
+                    genera, none of which are known to be noxious to
+                    man.
+
+          ff. The costal vein apparently is continued around the hind
+              margin of the wing; radius with at least four branches.
+
+            g. Wing ovate pointed, with numerous veins; crossveins, if
+                evident, before the basal third of the wing; veins very
+                hairy; very small moth-like flies. PSYCHODIDAE
+
+              h. With elongate biting proboscis; the petiole of the
+                  anterior forked cell of the wing (R_2) arises at or
+                  beyond the middle of the wing (fig. 163d). PHLEBOTOMUS
+                  Rdi.
+
+[Illustration: 163. Wings of Diptera. (_a_) Anopheles; (_b_)
+Prosimulium; (_c_) Johannseniella; (_d_) Phlebotomus (After Doerr and
+Russ); (_e_) Tersesthes (after Townsend); (_f_) Tabanus; (_g_)
+Symphoromyia; (_h_) Aphiochaeta; (_i_) Eristalis; (_j_) Gastrophilus;
+(_k_) Fannia; (_l_) Musca.]
+
+              hh. With shorter proboscis; the petiole of the anterior
+                  forked cell arises near the base of the wing.
+                  _Psychoda_, _Pericoma_, etc.
+
+            gg. The r-m crossvein placed at or beyond the center of the
+                wing; wings not folded roof-like over the abdomen.
+
+              h. Proboscis short, not adapted for piercing; wings bare
+                  (DIXIDAE); or wings scaled (CULICIDAE, Subf.
+                  CORETHRINAE).
+
+              hh. Proboscis elongate, adapted for piercing; wings
+                  scaled, fringed on the hind margin; antennae of the
+                  male bushy plumose. Mosquitoes. CULICIDAE (exclusive of
+                  CORETHRINAE)
+
+                i. Metanotum without setae.
+
+                  j. Proboscis strongly decurved; body with broad,
+                      appressed, metalescent scales; cell R_2 less than
+                      half as long as its petiole; claws of female
+                      simple, some of the claws of the male toothed.
+                      Several large southern species believed to feed
+                      only on nectar of flowers. _Megarhinus_ R. D.
+
+                  jj. Proboscis straight or nearly so, or otherwise
+                      different.
+
+                    k. Scutellum evenly rounded, not lobed; claws simple
+                        in both sexes. ANOPHELES Meig.
+
+                      l. Abdomen with clusters of broad outstanding
+                          scales along the sides; outstanding scales on
+                          the veins of the wing rather narrow,
+                          lanceolate; upper side of the thorax and
+                          scutellum bearing many appressed lanceolate
+                          scales. Florida and southward (CELLIA).
+
+                        m. Hind feet from the middle of the second
+                            segment largely or wholly snow white.
+
+                          n. With a black band at the base of the last
+                              segment of each hind foot. A.
+                              ALBIMANUS*[H] and TARSIMACULATA*
+
+                          nn. Without such a band A. ARGYRITARSIS*
+
+                        mm. Hind feet black, mottled with whitish and
+                            with bands of the same color at the sutures
+                            of the segments. W. I. A. MACULIPES
+
+                      ll. Abdomen without such a cluster of scales;
+                          outstanding scales of the wing veins rather
+                          narrow, lanceolate; tarsi wholly black.
+
+                        m. Deep black, thorax obscurely lined with
+                            violaceous, especially posteriorly; head,
+                            abdomen and legs black; no markings on the
+                            pleura; abdomen without trace of lighter
+                            bindings; wing scales outstanding, uniform,
+                            not forming spots, though little thicker at
+                            the usual points indicating the spottings.
+                            Florida. A. ATROPUS
+
+                        mm. Otherwise marked when the wings are
+                            unspotted.
+
+                          n. Wings unspotted.
+
+                            o. Petiole of the first forked cell (R_2)
+                                more than a third the length of the
+                                cell. Mississippi valley. A. WALKERI
+
+                            oo. Petiole of the first forked cell a third
+                                the length of the cell. Md. A. BARBERI
+
+                          nn. Wings spotted.
+
+                            o. Front margin of the wings with a patch of
+                                whitish and yellow scales at a point
+                                about two-thirds or three-fourths of the
+                                way from base to apex of wing.
+
+                              p. Veins of the wing with many broad
+                                  obovate outstanding scales; thorax
+                                  with a black dot near the middle of
+                                  each side. W. I. A. GRABHAMI*
+
+                              pp. The outstanding scales of the wings
+                                  rather narrow, lanceolate.
+
+                                q. Scales of the last vein of the wings
+                                    white, those at each end black;
+                                    R_{4+5} black scaled, the extreme
+                                    apex white scaled. Widely
+                                    distributed north and south (fig.
+                                    131). A. PUNCTIPENNIS
+
+                                  A dark variety from Pennsylvania has
+                                      been named A. PERPLEXENS.
+
+                                qq. Scales of the last vein of the wing
+                                    white, those at its apex black;
+                                    R_{4+5} white scaled and with two
+                                    patches of black scales. South and
+                                    the tropics. A. FRANCISCANUS and
+                                    PSEUDOPUNCTIPENNIS*
+
+                            oo. Front margin of the wings wholly black
+                                scaled.
+
+                              p. Last (anal) vein of the wings white
+                                  scaled with three patches of black
+                                  scales (fig. 132). New Jersey to
+                                  Texas. A. CRUCIANS*
+
+                              pp. Last vein of the wings wholly black
+                                  scaled.
+
+                                q. Widely distributed north and south
+                                    (fig. 130), (= MACULIPENNIS). A.
+                                    QUADRIMACULATUS*
+
+                                qq. Distributed from Rocky Mountains
+                                    westward. A. OCCIDENTALIS
+
+                    kk. Scutellum distinctly trilobed.
+
+                      l. Cell R_2 less than half as long as its petiole;
+                          thorax with metallic blue scales; median lobe
+                          of the scutellum not tuberculate; few small
+                          species which are not common. URANOTAENIA
+                          Arrib.
+
+                      ll. Cell R_2 nearly or quite as long as its
+                          petiole, or otherwise distinct.
+
+                        m. Femora with erect outstanding scales; occiput
+                            broad and exposed. Large species. P.
+                            CILIATA. P. HOWARDI PSOROPHORA R. D.
+
+                        mm. Femora without erect scales.
+
+                          n. Clypeus bearing several scales or hairs,
+                              scutellum with broad scales only; back of
+                              head with broad scales; scales along the
+                              sides of the mesonotum narrow; some or the
+                              claws toothed; thorax marked with a pair
+                              of silvery scaled curved stripes; legs
+                              black with white bands at the bases of
+                              some of the segments (fig. 134). Yellow
+                              Fever mosquito. AEDES (= STEGOMYIA)
+                              CALOPUS.
+
+                          nn. With another combination of characters.
+                              Numerous species of mosquitoes belonging
+                              to several closely related genera, widely
+                              distributed over the country. (_Culex_,
+                              _Aedes_, _Ochlerotatus_, etc.). CULEX in
+                              the wide sense.
+
+                ii. Metanotum with setae. _Wyeomyia_ (found in the United
+                    States); and related tropic genera.
+
+  bb. Antennae composed of three segments with a differentiated style or
+      bristle; third segment sometimes complex or annulate, in which
+      case the empodium is usually developed like the pulvilli, i.e.,
+      pad-like (fig. 161 g).
+
+    c. Empodium developed pad-like (pulvilliform) i.e., three nearly
+        equal membranous appendages on the underside of the claw (fig.
+        161g).
+
+      d. Squamae, head, and eyes large; occiput flattened or concave;
+          third segment of the antennae with four to eight annuli or
+          segments, proboscis adapted for piercing; body with fine
+          hairs, never with bristles; middle tibia with two spurs; wing
+          venation as figured (fig. 163f); marginal vein encompasses the
+          entire wing. Horse flies, greenheads, deer flies, gad flies
+          TABANIDAE[I]
+
+        e. Hind tibia with spurs at tip; ocelli usually present
+            (PANGONINAE)
+
+          f. Third joint of the antennae with seven or eight segments;
+              proboscis usually prolonged.
+
+            g. Each section the third antennal segment branched. Central
+                American species, _P. festae_. _Pityocera_ G. T.
+
+            gg. Sections of the third antennal segment not branched.
+
+              h. Upper corner of the eyes in the female terminating in
+                  an acute angle; wings of both sexes dark anteriorly.
+                  _G. chrysocoma_, a species from the eastern states.
+                  _Goniops_ Ald.
+
+              hh. Upper corner of the eye in the female not so
+                  terminating; wings nearly uniform in color, or
+                  hyaline.
+
+                i. Proboscis scarcely extending beyond the palpi; front
+                    of the female wide; much wider below than above. S.
+                    W. States. _Apatolestes_ Will.
+
+                ii. Proboscis extending beyond the palpi.
+
+                  j. Wing with cell M_3 closed. Tropic America. (=
+                      _Diclisa_) _Scione_ Wlk.
+
+                  jj. Cell M_3 open; ocelli present or absent. Two or
+                      three eastern species; many south and west
+                      PANGONIA Rdi.
+
+          ff. Third segment of the antenna with five divisions; ocelli
+              present.
+
+            g. First and second segments of the antenna short, the
+                second only half as long as the first, three western
+                species. SILVIUS Rdi.
+
+            gg. First and second segments of the antenna long, the
+                second distinctly over half as long as the first. Deer
+                flies. Many species, widely distributed. CHRYSOPS Meig.
+
+        ee. Hind tibia without spurs; ocelli absent.
+
+          f. Third segment of antenna with four divisions, no tooth or
+              angulation; wings marked with rings and circles of darker
+              coloring; front of the female very wide. Widely
+              distributed. _H. americana_, _H. punctulata_. HAEMATOPOTA
+              Meig.
+
+          ff. Third segment of the antenna with five divisions (fig.
+              161b).
+
+            g. Third segment of the antenna not furnished with a tooth
+                or distinct angular projection.
+
+              h. Body covered with metallic scales; front of female of
+                  normal width; front and middle tibiae greatly dilated.
+                  _L. lepidota_. _Lepidoselaga_ Macq.
+
+              hh. Body without metallic scales; antennae not very long,
+                  the third segment not cylindrical, not situated on a
+                  projecting tubercle; front of the female narrow.
+                  South. _D. ferrugatus._ (= _Diabasis_) _Diachlorus_ O.
+                  S.
+
+            gg. Third segment of the antenna furnished with a tooth or a
+                distinct angular projection.
+
+              h. Hind tibiae ciliate with long hairs. S. W. and tropics.
+                  _Snowiella_ and _Stibasoma_.
+
+              hh. Hind tibiae not ciliate.
+
+                i. Species of slender build, usually with a banded
+                    thorax and abdomen; third segment of the antenna
+                    slender, the basal prominence long; wings mostly
+                    with brownish markings. Tropic America.
+                    _Dichelacera_ Macq.
+
+                ii. Species of a stouter build; third segment of the
+                    antenna stout, its basal process short (fig. 161b).
+                    Many species, widely distributed TABANUS L.
+
+      dd. With another group of characters.
+
+        e. Squamae small, antennae variable, thinly pilose or nearly
+            bare species, without distinct bristles; wing veins not
+            crowded anteriorly, R_4 and R_5 both present, basal cells
+            large; middle tibiae at least with spurs. LEPTIDAE
+
+          f. Flagellum of the antenna more or less elongated, composed
+              of numerous more or less distinct divisions. XYLOPHAGINAE
+              and ARTHROCERATINAE.
+
+          ff. Antennae short, third segment simple, with arista or style;
+              face small, proboscis short LEPTINAE
+
+            g. Front tibiae each with one or two spurs, or if absent,
+                then no discal cell. _Triptotricha_, _Pheneus_,
+                _Dialysis_, _Hilarimorpha_.
+
+            gg. Front tibiae without terminal spurs, discal cell
+                present.
+
+              h. Hind tibiae each with a single spur.
+
+                i. Anal cell open (fig. 163g); third antennal segment
+                    kidney-shaped with dorsal or subdorsal arista; first
+                    antennal segment elongate and thickened. About a
+                    dozen species have been described from the United
+                    States, of which at least one (S. PACHYCERAS) is
+                    known to be a vicious blood sucker. SYMPHOROMYIA
+                    Frauenf.
+
+                ii. Anal cell closed; third antennal segment not
+                    kidney-shaped. _Chrysopila_, _Ptiolina_, _Spania_.
+
+              hh. Hind tibiae each with two spurs.
+
+                i. Third segment kidney-shaped, the arista subdorsal;
+                    anal cell closed. _Atherix_ Meig.
+
+                ii. Third segment of the antenna short and with terminal
+                    arista; anal cell open _Leptis_ Fabr. Two European
+                    species of this genus have been accused of blood
+                    sucking habits, but the record seems to have been
+                    based upon error in observation.
+
+        ee. With another combination of characters. STRATIOMYIIDAE,
+            CYRTIDAE, etc.
+
+    cc. Empodium bristlelike or absent.
+
+      d. Antennae apparently two segmented, with three-segmented arista,
+          wings (rarely wanting) with several stout veins anteriorly,
+          the weaker ones running obliquely across the wing (fig. 163h);
+          small, quick running, bristly, humpbacked flies. Several
+          genera; APHIOCHAETA, PHORA, TRINEURA, etc. PHORIDAE
+
+      dd. Flies with other characters.
+
+        e. No frontal lunule above the base of the antennae; both R_4
+            and R_5 often present; third segment of the antenna often
+            with a terminal bristle. ASILIDAE, MYDAIDAE,
+            APIOCERIDAE, THEREVIDAE, SCENOPINIDAE, BOMBYLIIDAE,
+            EMPIDIDAE, DOLICHOPODIDAE, LONCHOPTERIDAE.
+
+        ee. A frontal lunule above the base of the antennae; third
+            segment of the antenna always simple, i.e., not ringed,
+            usually with a dorsal arista; R_4 and R_5 coalesced into a
+            simple vein.
+
+          f. A spurious vein or fold between the radius and the media,
+              rarely absent; the cell R_{4+5} closed at the apex by vein
+              M_1; few or no bristles on the body, none on the head;
+              flies frequently with yellow markings. ERISTALIS (fig.
+              163i), HELOPHILUS, and many other genera. SYRPHIDAE
+
+          ff. No spurious vein present.
+
+            g. Body without bristles; proboscis elongate and slender,
+                often folding; front of both male and female broad.
+                CONOPIDAE
+
+            gg. Bristles almost always present on head, thorax, abdomen
+                and legs.
+
+              h. Arista terminal; hind metatarsus enlarged, sometimes
+                  ornamented, hind tarsus more or less flattened beneath.
+                  PLATYPEZIDAE
+
+              hh. Flies having a different combination of characters.
+
+                i. Head large, eyes occupying nearly the entire head;
+                    cell R_{4+5} narrowed in the margin; small flies.
+                    PIPUNCULIDAE
+
+                ii. Head and eyes not unusually large.
+
+                  j. Squamae (tegulae, or calyptrae, or alulae)
+                      not large, often quite small, the lower one
+                      lacking, or at most barely projecting from below
+                      the upper one (antisquama); front of both male and
+                      female broad, the eyes therefore widely separated;
+                      posthumeral and intraalar macrochaeta not
+                      simultaneously present; thorax usually without a
+                      complete transverse suture; postalar callus
+                      usually absent; the connectiva adjoining the
+                      ventral sclerites always visible; hypopleural
+                      macrochaetae absent; last section of R_{4+5}
+                      and M_{1+2} with but few exceptions nearly
+                      parallel; subcostal vein often wanting or
+                      vestigial or closely approximated to R_1; the
+                      latter often short, basal cells small, the
+                      posterior ones often indistinct or wanting;
+                      vibrissae present or absent. ACALYPTRATE
+                      MUSCOIDEA
+
+                    k. Subcosta present, distinctly separated from R_1
+                        at the tip; R_1 usually ends distad of the
+                        middle of the wing; the small basal cells of the
+                        wing distinct.
+
+                      l. A bristle (vibrissa) on each side of the face
+                          near the margin of the mouth. CORDYLURIDAE,
+                          SEPSIDAE, PHYCODROMIDAE, HETERONEURIDAE,
+                          HELOMYZIDAE.
+
+                      ll. No vibrissae present.
+
+                        m. Head nearly spherical, cheeks broad and
+                            retreating; proboscis short; the cell R_5
+                            closed or narrowed in the margin; legs very
+                            long; tarsi shorter than the tibiae. CALOBATA
+                            and other genera. MICROPEZIDAE
+
+                        mm. Flies with another combination of
+                            characters. RHOPALOMERIDAE, TRYPETIDAE,
+                            ORTALIDAE, SCIOMYZIDAE.
+
+                    kk. Subcosta absent or vestigial, or if present,
+                        then apparently ending in the costa at the point
+                        where R_1 joins it; R_1 usually ends in the
+                        costa at or before the middle of the wing.
+
+                      l. Arista long plumose, or pectinate above; oral
+                          vibrissae present; anal cell complete; costa
+                          broken at the apex of R_1. DROSOPHILA,
+                          PHORTICA, and other genera. DROSOPHILIDAE
+
+                      ll. With another combination of characters.
+
+                        m. The cell M and first M_2 not separated by a
+                            crossvein; anal cell absent; front bare or
+                            only bristly above; usually light colored
+                            flies. HIPPELATES, OSCINUS, and other
+                            genera. (See also m m m.) OSCINIDAE
+
+                        mm. Cell M and cell first M_2 often separated by
+                            a crossvein; anal cell present, complete,
+                            though frequently small; scutellum without
+                            spines or protuberances; oral vibrissae
+                            present; arista bare or short plumose; front
+                            bristly at vertex only; small dark flies.
+                            PIOPHILA (fig. 99), SEPSIS and other genera.
+                            SEPSIDAE
+
+                        mmm. The GEOMYZIDAE, AGROMYZIDAE,
+                            PSILIDAE, TRYPETIDAE, RHOPALOMERIDAE,
+                            BORBORIDAE and DIOPSIDAE differ in
+                            various particulars from either the
+                            OSCINIDAE and the SEPSIDAE noted above.
+
+                  jj. Squamae well developed, usually large, the lower
+                      one frequently projecting from below the upper
+                      one; both posthumeral and intraalar macrochaetae
+                      present; thorax with a complete transverse suture;
+                      postalar callus present and separated by a
+                      distinct suture from the dorsum of the thorax;
+                      front of the female broad, of the male frequently
+                      narrow, the eyes then nearly or quite contiguous;
+                      the connectiva adjoining the ventral sclerites
+                      either visible or not; hypopleural macrochaetae
+                      present or absent; subcosta always distinct in its
+                      whole course, R_1 never short. CALYPTRATE
+                      MUSCOIDEA[J]
+
+                    k. Oral opening small, mouth parts usually much
+                        reduced or vestigial. This family is undoubtedly
+                        of polyphyletic origin but for convenience it is
+                        here considered as a single family. OESTRIDAE.
+
+                      l. The costal vein ends at the tip of R_{4+5},
+                          M_{1+2} straight, not reaching the wing
+                          margin, hence cell R_5 wide open (fig. 163j);
+                          squamae small; arista bare; ovipositor of the
+                          female elongate. Larvae in the alimentary canal
+                          of horses, etc. GASTROPHILUS
+
+                        m. Posterior crossvein (m-cu) wanting; wings
+                            smoky or with clouds. Europe. G. PECORUM
+
+                        mm. Posterior crossvein (m-cu) present, at least
+                            in part.
+
+                          n. Wing hyaline with smoky median cross band,
+                              and two or three spots; posterior
+                              trochanters with hook in the male and a
+                              prominence in the female. World wide
+                              distribution. G. EQUI.
+
+                          nn. Wings without spots.
+
+                            o. Posterior crossvein (m-cu) distad of the
+                                anterior crossvein (r-m); legs,
+                                particularly the femora, blackish brown.
+                                Europe and North America. G.
+                                HAEMORRHOIDALIS
+
+                            oo. Posterior crossvein opposite or proximad
+                                of the anterior crossvein. Europe and
+                                North America. G. NASALIS
+
+                      ll. The costal vein ends at the tip of M_{1+2},
+                          M_{1+2} with a bend, the cell R_5 hence much
+                          narrowed in the margin, or closed.
+
+                        m. Proboscis geniculate, inserted in a deep
+                            slit; female without extricate ovipositor;
+                            arista either bare or plumose; squamae large;
+                            facial grooves approximated below.
+
+                          n. Arista bare, short. Larvae in rodents.
+                              Tropic America. _B. princeps_. _Bogeria_
+                              Austen
+
+                          nn. Arista pectinate above.
+
+                            o. Tarsi broadened and flattened, hairy,
+                                anal lobe of the wing large. Larvae in
+                                rodents. A number of American species.
+                                _Cuterebra_.
+
+                            oo. Tarsi slender, not hairy; anal lobe of
+                                the wing moderate. Larvae in man and
+                                other mammals. Tropic America. D.
+                                CYANIVENTRIS. DERMATOBIA Br.
+
+                        mm. Mouth parts very small, vestigial; arista
+                            bare.
+
+                          n. Facial grooves approximated below, leaving
+                              a narrow median depression or groove.
+
+                            o. Cell R_5 closed and petiolate, body
+                                nearly bare. Larvae in the nasal cavities
+                                of the smaller Ungulates. The sheep bot
+                                fly. O. OVIS. Widely distributed OESTRUS
+                                L.
+
+                            oo. Cell R_5 narrowly open, body hairy.
+                                Larvae parasitic on deer. Europe and
+                                America. _Cephenomyia_ Latr.
+
+                          nn. Facial grooves far apart, enclosing
+                              between them a broad shield-shaped
+                              surface; squamae large; female with
+                              elongate ovipositor. Larvae hypodermatic on
+                              Ungulates HYPODERMA Clark
+
+                            o. Palpi wanting; tibiae thickened in the
+                                middle.
+
+                              p. Hair at apex of the abdomen yellow;
+                                  legs including femora yellowish brown.
+                                  H. DIANA
+
+                              pp. Hair at the apex of the abdomen
+                                  reddish yellow. Europe and America.
+
+                                q. Tibiae and tarsi yellow; femora black.
+                                    H. LINEATA
+
+                                qq. Legs black with black hair; tips of
+                                    hind tibia and tarsi yellowish
+                                    brown. H. BOVIS
+
+                            oo. Palpi small, globular; tibiae
+                                cylindrical, straight. On reindeer. _O.
+                                tarandi_ _Oedemagena_ Latr.
+
+                    kk. Oral opening of the usual size; mouth parts not
+                        vestigial.
+
+                      l. Hypopleurals wanting; if three sternopleurals
+                          are present the arrangement is 1:2;
+                          conjunctiva (fig. 161c) of the venter usually
+                          present; if the terminal section of M_{1+2} is
+                          bent it has neither fold nor appendage
+                          (ANTHOMYIIDAE of Girschner).
+
+                        m. Sternopleurals wanting; M_{1+2} straight
+                            toward the apex, costa ends at or slightly
+                            beyond the tip of R_{4+5}; mouth parts
+                            vestigial. GASTROPHILINAE. See OESTRIDAE
+
+                        mm. Sternopleurals present, if rarely absent
+                            then differing in other characters.
+
+                          n. Caudal margin of the fifth ventral
+                              abdominal sclerite of the male deeply
+                              notched on the median line usually to
+                              beyond the middle; abdomen often
+                              cylindrical or linear; abdomen often with
+                              four to eight spots; eyes of the male
+                              usually widely separated; sternopleurals
+                              three, arranged in an equilateral
+                              triangle; subapical seta of the hind tibia
+                              placed very low; M_{1+2} straight; anal
+                              vein abbreviated; wings not rilled.
+                              _Caenosia_, _Caricea_, _Dexiopsis_,
+                              _Hoplogaster_, _Schoenomyia_, etc.
+                              (COENOSINAE)[K]. ANTHOMYIIDAE in part
+
+                          nn. Caudal margin of the fifth ventral
+                              abdominal sclerite of the male incurved,
+                              rarely deeply cleft, rarely entire, in a
+                              few genera deeply two or three notched;
+                              M_{1+2} straight or curved; abdomen
+                              usually short or elongate oval;
+                              sternopleurals, if three are present,
+                              arranged in the order 1:2 in a right
+                              triangle. (MUSCINAE-ANTHOMYIINAE of
+                              Girschner)
+
+                            o. M_{1+2} straight, hence cell R_5 not
+                                narrowed in the margin. ANTHOMYIIDAE in
+                                part
+
+                              p. Underside of the scutellum more or less
+                                  sparsely covered with fine hairs; anal
+                                  vein nearly always reaches the hind
+                                  margin of the wing; extensor surface
+                                  of the hind tibiae with a number of
+                                  stout setae; squamae often small and
+                                  equal. ANTHOMYIA, _Chortophila_,
+                                  _Eustalomyia_, _Hammomyia_,
+                                  _Hylemyia_, _Prosalpia_, _Pegomyia_,
+                                  etc. HYLEMYINAE-PEGOMYINAE
+
+                              pp. Underside of the scutellum bare; anal
+                                  vein does not reach the wing margin.
+
+                                q. First anal vein short, second anal
+                                    suddenly flexed upwards; hind tibiae
+                                    each with one or two strong setae on
+                                    the extensor surface. FANNIA (=
+                                    HOMALOMYIA), _Coelomyia_,
+                                    _Choristoma_, _Euryomma_, _Azelia_,
+                                    etc. FANNINAE-AZELINAE
+
+                                qq. Anal veins parallel or divergent.
+
+                                  r. Setae on the exterior surface of the
+                                      hind tibiae wanting (except in
+                                      _Limnaricia_ and _Coenosites_),
+                                      lower squama not broadened to the
+                                      margin of the scutellum.
+                                      _Leucomelina_, _Limnophora_,
+                                      _Limnospila_, _Lispa_, _Mydaea_,
+                                      _Spilogaster_, etc.
+                                      MYDAEINAE-LIMNOPHORINAE
+
+                                  rr. One (rarely more) seta on the
+                                      extensor surface of the hind
+                                      tibia; squamae usually large and
+                                      unequal. HYDROTAEA, _Aricia_,
+                                      _Drymeia_, _Ophyra_, _Phaonia_ (=
+                                      _Hyetodesia_), _Pogonomyia_,
+                                      _Trichophthicus_, etc. ARICINAE
+
+                            oo. M_{1+2} curved or bent, hence the cell
+                                R_5 more or less narrowed in the margin.
+                                (MUSCINAE). MUSCIDAE in part. See
+                                page 303 for generic synopsis.
+
+                      ll. Hypopleurals present; when three
+                          sternopleurals are present the arrangement is
+                          2:1 or 1:1:1. (TACHINIDAE of Girschner)
+
+                        m. Conjunctiva of the ventral sclerites of the
+                            abdomen present, frequently well developed,
+                            surrounding the sclerites.
+
+                          n. Mouth parts vestigial. OESTRIDAE. See page
+                              297 for generic synopsis.
+
+                          nn. Mouth parts well developed.
+
+                            o. M_{1+2} straight, hence cell R_5 wide
+                                open in the margin; costa ending at the
+                                tip of R_5; three sternopleurals
+                                present; antennal arista plumose.
+                                _Syllegoptera_. Europe.
+                                (SYLLEGOPTERINAE). DEXIIDAE in part
+
+                            oo. M_{1+2} bent, hence cell R_5 narrowed in
+                                the margin; sternopleurals rarely
+                                wanting, usually 1:1 or 0:1; facial
+                                plate strongly produced below vibrissal
+                                angle like the bridge of the nose;
+                                antennal arista bare. Parasitic on
+                                Hemiptera and Coleoptera. _Allophora_,
+                                _Cistogaster_, _Clytia_, _Phasia_, etc.
+                                (PHASIINAE) TACHINIDAE in part.
+
+                        mm. Conjunctiva of the ventral sclerites
+                            invisible (fig. 161a).
+
+                          n. Second ventral sclerite of the abdomen
+                              lying with its edges either upon or in
+                              contact with the ventral edges of the
+                              corresponding dorsal sclerite.
+
+                            o. Outermost posthumeral almost always lower
+                                (more ventrad) in position than the
+                                presutural macrochaeta; fifth ventral
+                                abdominal sclerite of the male cleft
+                                beyond the middle, often strongly
+                                developed; body color very frequently
+                                metallic green or blue, or yellow;
+                                arista plumose. (CALLIPHORINAE)
+                                MUSCIDAE in part.
+
+                              See page 303 for generic synopsis.
+
+                            oo. Outermost posthumeral macrochaeta on
+                                level or higher (more dorsad) than the
+                                presutural macrochaeta; arista bare,
+                                pubescent, or plumose only on the basal
+                                two-thirds; body coloring usually
+                                grayish (fig. 106). SARCOPHAGIDAE
+
+                              p. Fifth ventral sclerite of the male
+                                  either wanting or with the caudal
+                                  margin straight; presutural intraalar
+                                  rarely present. (SARCOPHAGINAE)
+
+                                q. Fifth ventral abdominal sclerite of
+                                    the male much reduced, the remaining
+                                    segments with straight posterior
+                                    margin, overlapping scale-like; in
+                                    the female only segment one and two
+                                    scale-like, the others wholly or in
+                                    part covered; sternopleurals usually
+                                    three or more. SARCOPHAGA and
+                                    related genera.
+
+                                qq. Fifth ventral sclerite of the male
+                                    plainly visible; sternopleurals
+                                    usually two. SARCOPHILA,
+                                    WOHLFAHRTIA, _Brachycoma_,
+                                    _Hilarella_, _Miltogramma_,
+                                    _Metopia_, _Macronychia_, _Nyctia_,
+                                    _Paramacronychia_, _Pachyphthalmus_,
+                                    etc.
+
+                              pp. Fifth ventral abdominal sclerite of
+                                  the male cleft to beyond the middle;
+                                  ventral sclerites usually visible,
+                                  shield-like. _Rhinophora_, _Phyto_,
+                                  _Melanophora_ RHINOPHORINAE
+
+[Illustration: 164. Glossina palpalis. (x4.) After Austen.]
+
+                          nn. Second ventral abdominal sclerite as well
+                              as the others more or less covered,
+                              sometimes wholly, by the edges of the
+                              dorsal sclerite.
+
+                            o. The presutural intraalar wanting; ventral
+                                sclerites two to five nearly or quite
+                                covered by the edges of the
+                                corresponding dorsal sclerites; base of
+                                the antennae usually at or below the
+                                middle of the eye; arista usually
+                                plumose; legs usually elongate;
+                                abdominal segments with marginal and
+                                often discal macrochaetae. DEXIIDAE
+
+                            oo. Presutural intraalar present, if absent,
+                                then the ventral sclerites broadly
+                                exposed or the fifth ventral sclerite
+                                vestigial; base of the antennae usually
+                                above the middle of the eye; arista
+                                bare; at least two posthumerals and
+                                three posterior intraalars present.
+                                Parasitic on caterpillars, etc.
+                                TACHINIDAE
+
+
+SYNOPSIS OF THE PRINCIPAL GENERA OF THE MUSCIDAE OF THE WORLD
+
+a. Proboscis long, directed forward, adapted for piercing, or oral
+    margin much produced, snout-like.
+
+  b. Oral margin produced snout-like; vibrissa placed high above the
+      oral margin; antennal arista either pectinate or more or less
+      plumose.
+
+    c. Antennal arista short or long-plumose; neither sex with distinct
+        orbital bristles.
+
+      d. No facial carina between the antennae. RHYNCHOMYIINAE
+
+        e. Arista short-plumose. _R. speciosa._ Europe. _Rhynchomyia_ R.
+            D.
+
+        ee. Arista long-plumose. _I. phasina_. Europe and Egypt.
+            _Idiopsis_. B. B.
+
+      dd. With flattened carina, the bases of the antennae separated; no
+          abdominal macrochaetae. COSMININAE _C. fuscipennis_. South
+          Africa. _Cosmina_
+
+    cc. Antennal arista pectinate; bases of the antennae separated by a
+        flattened carina. RHINIINAE R. D.
+
+      d. Cell R_5 open, or closed at the margin.
+
+        e. Third segment of the antenna twice as long as the second;
+            claws of both sexes short; cell R_5 open. _I. lunata._
+            Eastern Hemisphere. _Idia_ Meigen
+
+        ee. Third segment of the antenna three times as long as the
+            second; cell R_5 open or closed; claws of the male long and
+            slender, of the female shorter than the last tarsal joint.
+            _I. mandarina_, China. _Idiella_ B. B.
+
+      dd. Cell R_5 petiolate. _Rhinia_; and _Beccarimyia_ Rdi.
+
+  bb. Proboscis long, directed forward, adapted for piercing. STOMOXINAE
+
+    c. Arista flat, pectinate above with plumose rays; sternopleurals
+        1:2; bases of the veins R_1 and R_{4+5} without setae; base of
+        the media bowed down; apical cell opens before the apex of the
+        wing. African species. GLOSSINA Wied.
+
+      d. Species measuring over twelve mm. in length. _G. longipennis_
+          and FUSCA.
+
+      dd. Species less than twelve mm. in length.
+
+        e. All segments of the hind tarsi black.
+
+          f. The fourth and fifth segments of the fore tarsi black;
+              antennae black (fig. 164). G. PALPALIS R. D.
+
+          ff. Otherwise marked. _G. bocagei_, _tachinoides_,
+              _pallicera._
+
+        ee. First three segments of the hind tarsi are yellow, the
+            fourth and fifth segments are black.
+
+          f. Fourth and fifth segments of the first and second pair of
+              tarsi are black.
+
+            g. The yellow bands of the abdominal segments occupy a third
+                of the segment (fig. 165). G. MORSITANS Westw.
+
+            gg. The yellow band on each segment of the abdomen occupies
+                a sixth of the segment. G. LONGIPALPIS Wied.
+
+          ff. Tarsi of the first and second pairs of legs wholly yellow.
+              _G. pallidipes_ Austen
+
+    cc. Rays of the arista not plumose; only one or two sternopleurals;
+        base of the media not strongly bowed down; apical cell opens at
+        or very near the apex of the wing.
+
+      d. Vein R_{4+5} without setae at the base; palpi about as long as
+          the proboscis.
+
+        e. Arista pectinate (i.e. rays on one side only), the rays often
+            undulate; two yellow sternopleurals often difficult to
+            detect; vein M_{1+2} only slightly bent, the apical cell
+            hence wide open. The horn fly, H. IRRITANS (= _Lyperosia
+            serrata_) and related species. Widely distributed (figs.
+            167, 168). HAEMATOBIA R. D. not B. B.
+
+[Illustration: 165. Glossina morsitans. (x4.) After Austen.]
+
+        ee. Arista also with rays below; vein M_{1+2} more strongly
+            bent, the apical cell hence less widely open.
+
+          f. Palpi strongly spatulate at the tips, lower rays of the
+              arista about six in number, B. SANGUINOLENTUS. South Asia.
+              BDELLOLARYNX Austen
+
+          ff. Palpi feebly spatulate; apical cell of the wing narrowly
+              open slightly before the tip; sternopleurals black,
+              anterior bristle sometimes absent. H. ATRIPALPIS. Europe.
+              HAEMATOBOSCA Bezzi
+
+      dd. Vein R_{4+5} with setae at the base.[L]
+
+        e. Veins R_1 and R_{4+5} with setae at the base; two equally
+            prominent sternopleural macrochaetae; arista with rays both
+            above and below; palpi as long as the proboscis; apical cell
+            of the wing wide open. L. TIBIALIS. (_Haematobia_ B. B. not
+            R. D.). LYPEROSIOPS Town.
+
+        ee. Only vein R_{4+5} with basal setae; anterior sternopleural
+            macrochaeta wanting; arista pectinate.
+
+          f. Palpi as long as the proboscis, the latter stout, with
+              fleshy terminal labellae; apical cell narrowly open;
+              sternopleural macrochaetae black. S. MACULOSA from Africa
+              and related species from Asia. STYGEROMYIA Austen
+
+          ff. Palpi much shorter than the proboscis, the latter pointed
+              at the apex, without fleshy labellae; apical cell of the
+              wing wide open. S. CALCITRANS, the stable fly and related
+              species. Widely distributed in both hemispheres (fig.
+              110). STOMOXYS Geof.
+
+aa. Proboscis neither slender nor elongate, the labellae fleshy and not
+    adapted for piercing.
+
+  b. Hypopleurae without a vertical row of macrochaetae. MUSCINAE
+
+    c. Arista bare; distal portion of M_{1+2} broadly curved at the end;
+        hypopleurae with a sparse cluster of fine hairs. _S.
+        braziliana_, Southern States and southward. _Synthesiomyia_ B.
+        B.
+
+    cc. Arista pectinate or plumose.
+
+      d. Arista pectinate. _H. vittigera_, with the posterior half of
+          the abdomen metallic blue. Mexico. _Hemichlora_ V. d. W.
+
+      dd. Arista plumose.
+
+        e. Middle tibia with one or more prominent setae on the inner
+            (flexor) surface beyond the middle, or inner surface very
+            hairy.
+
+          f. R_1 ends distad of the m-cu crossvein; M_{1+2} with a broad
+              curve near its apical end. (= _Neomesembrina_ Schnabl. =
+              _Metamesembrina_ Town). _M. meridiana._ Europe.
+              _Mesembrina_ Meigen
+
+          ff. R_1 ends proximad of the m-cu crossvein.
+
+            g. Eyes pilose, sometimes sparsely in the female.
+
+              h. Female with two or three stout orbital setae; the hind
+                  metatarsus of the male thickened below at the base and
+                  penicillate. _D. pratorum._ Europe. _Dasyphora_ R.
+                  D.[M]
+
+              hh. Neither sex with orbital setae.
+
+                i. Abdomen without macrochaetae; arista plumose. _C.
+                    asiatica._ Eastern Hemisphere. _Cryptolucilia_ B. B.
+
+                ii. Abdomen with strong macrochaetae; arista very
+                    short-plumose, nearly bare. _B. tachinina._ Brazil.
+                    _Reinwardtia_ B. B.
+
+            gg. Eyes bare.
+
+              h. Body densely pilose; thoracic macrochaetae wanting;
+                  middle tibiae much elongate and bent; last section of
+                  M_{1+2} with a gentle curve. H. (_Mesembrina_)
+                  _mystacea, et al._, Europe and _H. solitaria_, N.
+                  America. _Hypodermodes_ Town.
+
+              hh. Body not densely pilose.
+
+                i. Dorsocentrals six; last section of M_{1+2} with a
+                    gentle curve.
+
+                  j. Inner dorsocentrals ("acrostichals") wanting;
+                      sternopleurals arranged 1:3. _P. cyanicolor_,
+                      _cadaverina_, etc. Europe and America _Pyrellia_
+                      R. D.
+
+                  jj. Inner dorsocentrals ("acrostichals") present;
+                      sternopleurals arranged 1:2. E. _latreillii._
+                      North America. _Eumesembrina_ Town.
+
+                ii. Dorsocentrals five; inner dorsocentrals present;
+                    last section of M_{1+2} with a rounded angle;
+                    sternopleurals arranged 1:2. _P. cornicina_ Europe
+                    and America. (_Pseudopyrellia_ Girsch.) _Orthellia_
+                    R. D.
+
+        ee. Middle tibia without a prominent bristle on the inner
+            surface beyond the middle.
+
+[Illustration: 166. Pycnosoma marginale. (x4.) After Graham-Smith.]
+
+          f. Squamula thoracalis broadened mesad and caudad as far as
+              the scutellum.
+
+            g. Sternopleural macrochaetae arranged in an equilateral
+                triangle; front of both sexes broad; genae bare;
+                dorsocentrals six, small; wing not rilled. (To
+                COENOSINAE). _Atherigona_ Rdi.
+
+            gg. Sternopleural macrochaetae when three are present,
+                arranged in a right triangle.
+
+              h. Last section of M_{1+2} with a more or less rounded
+                  angle (fig. 163l).
+
+                i. Eyes of the male pilose or pubescent, of the female
+                    nearly bare; m-cu crossvein usually at or proximad
+                    of the mid-distance between the r-m crossvein and
+                    the bend of M_{1+2}. P. (= _Placomyia_ R. D.)
+                    _vitripennis_. _Plaxemyia_ R. D.
+
+                ii. Eyes bare; the m-cu crossvein always nearer to the
+                    bend of M_{1+2} than to the r-m crossvein.
+
+                  j. Apex of the proboscis when extended reveals a
+                      circlet of stout chitinous teeth. P. INSIGNIS
+                      Austen, of India, bites both man and animals. (=
+                      _Pristirhynchomyia_.) PHILAEMATOMYIA Austen
+
+                  jj. Apex of the proboscis without black teeth.
+
+                    k. Eyes of male separated by a distance equal to a
+                        fourth the width of the head. House or typhoid
+                        fly. M. DOMESTICA L. Widely distributed. MUSCA
+                        L.
+
+                    kk. Eyes of the male contiguous. E. CORVINA. Europe.
+                        EUMUSCA Town
+
+              hh. Last section of M_{1+2} with a gentle curve (fig.
+                  102).
+
+                i. Eyes pilose.
+
+                  j. Claws in the male somewhat elongated; no orbitals
+                      in either sex; antennae separated at the base by a
+                      flat carina; abdomen marked with red or yellow.
+                      _G. maculata._ Europe and America. _Graphomyia_ R.
+                      D.
+
+                  jj. Claws short and equal in the two sexes; two or
+                      three stout orbital macrochaetae in the
+                      female; R_1 scarcely produced beyond the r-m
+                      crossvein; eyes contiguous in the male. _P.
+                      obsoleta._ Brazil. _Phasiophana_ Br.
+
+                ii. Eyes bare; fronto-orbital macrochaetae in a double
+                    row, antennae contiguous at the base.
+
+                  j. One or more pairs of well developed anterior inner
+                      dorsocentral (acrostichal) macrochaetae; seta on
+                      extensor surface of hind tibia. M. ASSIMILIS,
+                      STABULANS, etc. Europe and America. MUSCINA R. D.
+
+                  jj. Anterior inner dorsocentrals and the setae; on the
+                      extensor surface of the hind tibia wanting. _M.
+                      micans_, etc. Europe and North America. _Morellia_
+                      R. D.
+
+          ff. Squamula thoracalis not broadened mesad and caudad, not
+              reaching the margin of the scutellum; macrochaetae on
+              extensor surface of the hind tibia wanting.
+
+            g. Eyes pubescent. _M. meditabunda._ Europe and America.
+                _Myiospila_ Rdi.
+
+            gg. Eyes bare; R_1 ends before the middle of the wing. A
+                number of species from the tropics of both hemispheres.
+                _Clinopera_ V. d. W.
+
+  bb. Hypopleurae with a vertical row of macrochaetae.
+
+    c. Eyes pubescent.
+
+      d. R_1 ends about opposite the r-m crossvein; basal section of
+          R_{4+5} bristly nearly to the crossvein; _S. enigmatica_.
+          Africa. _Somalia_ Hough
+
+      dd. R_1 ends distad of the r-m crossvein.
+
+        e. Eastern hemisphere. Australasia. _N. ochracea_,
+            _dasypthalma_. _Neocalliphora_ Br.
+
+        ee. Western Hemisphere. _T. muscinum._ Mexico. _Tyreomma_ V. d.
+            W.
+
+    cc. Eyes bare.
+
+      d. The vibrissal angle situated at a noticeable distance above the
+          level of the margin of the mouth.
+
+        e. Sternopleural macrochaetae arranged in the order 1:1.
+
+          f. Genae with microchaetae.
+
+            g. Body grayish, with depressed yellow woolly hair among the
+                macrochaetae; wings folded longitudinally over the body
+                when at rest. Cluster flies. _P. rudis_ and related
+                species, widely distributed. _Pollenia_ R. D.[N]
+
+            gg. Body metallic blue or green. Eastern Hemisphere.
+
+              h. Vibrissal angle placed very high above the oral margin;
+                  a carina between the antennae; outer posthumeral
+                  wanting; anterior intraalar present. _T. viridaurea_.
+                  Java. _Thelychaeta_ Br.
+
+[Illustration: 167. Horn fly. (_a_) egg; (_b_) larva; (_c_) puparium;
+(_d_) adult. (x4). Bureau of Entomology]
+
+              hh. Vibrissal angle moderately high above the oral margin;
+                  carina small or wanting; no post humeral macrochaeta;
+                  lower squamae hairy above. (= _Paracompsomyia_ Hough)
+                  (fig. 166). _Pycnosoma_ Br.
+
+          ff. Genae bare. _S. terminata_. Eastern Hemisphere.
+              _Strongyloneura_ Bigot
+
+        ee. Sternopleurals arranged 2:1.
+
+          f. Body metallic green or blue, with gray stripes; genae hairy
+              to the lower margin; post humerals often wanting; lower
+              squamae bare above. (= _Compsomyia_ Rdi.). CHRYSOMYIA R. D.
+
+            g. With one or two orbitals; height of bucca less than half
+                the height of the eye. South and east U. S. (fig. 107).
+                C. MARCELLARIA
+
+            gg. No orbitals; height of bucca about a third less than
+                height of eye. West U. S. _C. wheeleri_ Hough
+
+          ff. Body black or sordidly metallic greenish gray, usually
+              yellow pollinose or variegate; genae at most hairy above.
+              _N. stygia_. Eastern Hemisphere. _Neopollenia_ Br.
+
+      dd. Vibrissal angle situated nearly on a level of the oral margin.
+
+        e. Species wholly blackish, bluish, or greenish metallic in
+            color.
+
+          f. First section of R_{4+5} with at most three or four small
+              bristles at the immediate base.
+
+            g. The bend of M_{1+2} a gentle curve; costal spine present;
+                cell R_5 closed, ending before the apex of the wing. _S.
+                cuprina._ Java. _Synamphoneura_ Bigot
+
+            gg. Bend of M_{1+2} angular; or the insect differs in other
+                characters; dorsal surface of the squamula thoracalis
+                hairy (except in _Melinda_); arista plumose only on the
+                basal two-thirds (except usually in _Calliphora_ and
+                _Eucalliphora_).
+
+[Illustration: 168. Head of horn-fly (Lyperosia irritans); (_a_) female;
+(_b_) male; (_c_) lateral aspect of female. Bureau of Entomology]
+
+              h. Arista plumose only on the basal two-thirds.
+
+                i. Base of the antennae ventrad of the middle of the
+                    eye; eyes of the male nearly contiguous; genae
+                    hairy; second abdominal segment with median marginal
+                    macrochaetae; two, rarely three, postsutural
+                    intraalar macrochaetae.
+
+                  j. Squamula thoracalis dorsally with long black hairs;
+                      male hypopygium two-segmented, large, projecting;
+                      claws and pulvilli of the male elongate; three
+                      strong sternopleural macrochaetae; genae at
+                      least half the width of the eye; buccae (cheeks)
+                      half the height of the eyes; oviviparous. _O.
+                      sepulcralis._ Europe. _Onesia_ R. D.
+
+                  jj. Dorsal surface of the squamula thoracalis bare;
+                      male hypopygium small, scarcely projecting below;
+                      claws and pulvilli not elongate; two stout
+                      sternopleural macrochaetae, sometimes with a
+                      delicate one below the anterior; genae nearly
+                      linear in the male; buccae about a third of the eye
+                      height; oviparous. _M. caerulea_. Europe.
+                      _Melinda_. R. D.
+
+[Illustration: 169. Lateral and dorsal aspects of the thorax, and
+frontal aspect of the head of a muscoidean fly, with designations of the
+parts commonly used in taxonomic work.]
+
+                ii. Base of the antennae dorsad of the middle of the eye;
+                    eyes of both sexes distinctly separated; dorsal
+                    surface of the squamula thoracalis with black hairs;
+                    two postsutural intraalar macrochaetae.
+
+                  j. Hypopygium of the male large, with a pair of
+                      slightly curved forceps whose ends are concealed
+                      in a longitudinal slit in the fifth ventral
+                      sclerite; third posterior inner dorso-central
+                      (acrostichal) macrochaetae absent; anterior
+                      intraalar rarely present; abdomen usually not
+                      pollinose; the second segment without median
+                      marginal macrochaetae; face yellow. _C.
+                      mortuorum_, _cadaverina_, and related species.
+                      Both hemispheres. _Cynomyia_ R. D.[O]
+
+[Illustration: 170. Sepsis violacea; puparium and adult. (See page 297.)
+After Howard.]
+
+                  jj. Three pairs of posterior inner dorsocentrals
+                      (acrostichals) present; second abdominal segment
+                      with a row of marginal macrochaetae; genae
+                      hairy, at least above.
+
+                    k. Hypopygium of the male with a projecting style.
+                        _S. stylifera_. Europe. _Steringomyia_ Pok.
+
+
+                    kk. Hypopygium of the male without style. _A.
+                        stelviana_ B. B. _Acrophaga_ B. B.
+
+              hh. Arista usually plumose nearly to the tip; posterior
+                  dorsocentrals and inner dorsocentrals (acrostichals)
+                  well developed; dorsal surface of the squamula
+                  thoracalis hairy; abdomen metallic and usually
+                  pollinose; genae hairy.
+
+                i. With one pair of ocellar macrochaetae. C. VOMITORIA,
+                    ERYTHROCEPHALA, VIRIDESCENS, and related species.
+                    Both hemispheres. CALLIPHORA R. D.
+
+                ii. With two strong pairs of ocellar macrochaetae. _E.
+                    latifrons._ Pacific slope of the U. S.
+                    _Eucalliphora_ Town.
+
+          ff. First section of R_{4+5} bristly near or quite half way to
+              the small crossvein; dorsal surface of the squamula
+              thoracalis is bare; the hypopygium of the male is
+              inconspicuous.
+
+            g. Genae bare; posterior inner and outer dorsocentrals
+                distinct and well developed. _L. caesar_, _sericata_,
+                _sylvarum_, and related species. Widely distributed in
+                both hemispheres (fig. 103). LUCILIA R. D.
+
+            gg. Genae with microchaetae, at least down to the
+                level of the base of the arista.
+
+              h. Mesonotum flattened behind the transverse suture.
+
+                i. Posterior dorsocentrals inconstant and unequally
+                    developed; one pair of posterior inner
+                    dorsocentrals. _P. terraenovae._ North America.
+                    _Protophormia_ Town.
+
+                ii. Posterior dorsocentrals well developed, the inner
+                    dorsocentrals (acrostichals) unequally developed.
+                    _P. azurea_, _chrysorrhoea_, etc. Europe and America.
+                    _Protocalliphora_ Hough
+
+              hh. Mesonotum not flattened behind the transverse suture;
+                  posterior inner and outer dorsocentrals inconstant and
+                  unequally developed. _P. regina._ Europe and America.
+                  _Phormia_ R. D.
+
+        ee. Species more or less rufous or yellow in color.
+
+          f. Anterior dorsocentrals wanting; first section of the
+              R_{4+5} at most only bristly at the base, bend near apex
+              of M_{1+2} rectangular, R_1 ends over the crossvein;
+              fronto-orbital macrochaeta absent; eyes of the male
+              contiguous. _C. semiviridis._ Mexico. _Chloroprocta_
+              V. d. W
+
+          ff. With another combination of characters.
+
+            g. Body robust, of large size, abdomen elongate, not round;
+                genae with several ranges of microchaetae;
+                vibrissal ridges strongly convergent; abdomen with well
+                developed macrochaetae; costal spine usually absent;
+                eyes of the male widely separated.
+
+[Illustration: 171. Stigmata of the larvae of Muscoidea. Third instar.
+(_a_) Cynomyia cadaverina; (_b_) Phormia regina; (_c_) Chrysomyia
+macellaria; (_d_) Musca domestica; (_e_) Sarcophaga sp.; (_f_) Oestris
+ovis; (_g_) Gastrophilus equi; (_h_) Sarcophaga sp.; (_i_) Pegomyia
+vicina; (_j_) Protocalliphora azurea; (_k_) Hypoderma lineata; (_l_)
+Muscina stabulans. Magnification for f, g, and k, x25; all others, x50.]
+
+              h. Peristome broad, pteropleural macrochaetae
+                  distinct; one or two sternopleurals; in the female a
+                  single orbital macrochaeta; last abdominal segment
+                  without discal macrochaetae; hypopygial processes
+                  of the male with a long stylet; second abdominal
+                  segment of the female sometimes much elongate. A.
+                  LUTEOLA (fig. 86). Africa. The sub-genus
+                  _Choeromyia_ Roub. is included here. AUCHMEROMYIA B.
+                  B.
+
+              hh. Peristome narrow; no pteropleurals, two
+                  sternopleurals; two orbitals in the female; second
+                  segment not elongate; the fourth with two well
+                  developed discal macrochaetae. B. DEPRESSA. Africa.
+                  BENGALIA R. D
+
+            gg. With another combination of characters.
+
+              h. Costal spine present; body in part black; antennae
+                  noticeably shorter than the epistome, inserted above
+                  the middle of the eye and separated from each other by
+                  a carina; abdominal segments with marginal
+                  macrochaetae; sternopleurals 2:1 or 1:1.
+                  _Paratricyclea_ Villen.
+
+              hh. Costal spine not distinct, or if present, insect
+                  otherwise different.
+
+                i. Genae with several ranges of microchaetae;
+                    vibrissal ridges strongly converging; peristome
+                    broad; arista moderately plumose; sternopleurals
+                    usually 1:1; color entirely testaceous. C.
+                    ANTHROPOPHAGA (fig. 87) and GRUNBERGI. Africa.
+                    CORDYLOBIA Grunb.
+
+                ii. Genae bare or with but one range of setae;
+                    vibrissal ridges less converging; peristome narrow;
+                    arista long plumose.
+
+                  j. Genae with a single row of microchaetae.
+
+                    k. Sternopleurals 2:1; color entirely testaceous.
+                        _Ochromyia_ Macq.[P]
+
+                    kk. Sternopleurals 1:1. _P. varia_ Hough. Africa.
+                        _Parochromyia_ Hough
+
+                  jj. Genae bare.
+
+                    k. Basal section of R_{4+5} bristly only at the
+                        immediate base, distally M_{1+2} with a broad
+                        curve; distal portion of the abdomen metallic;
+                        sternopleurals usually 1:1, rarely 2:1. _M.
+                        aeneiventris_ Wd. Tropic America.
+                        _Mesembrinella._ G. T.
+
+                    kk. R_{4+5} bristly at least nearly half way to the
+                        small crossvein; sternopleurals 1:1.
+
+                      l. Macrochaetae of the abdomen marginal;
+                          neither sex with orbitals; no carina between
+                          the base of the antennae; three pairs of
+                          presutural inner dorsocentrals. Eastern
+                          hemisphere. _T. ferruginea._ _Tricyclea V. d.
+                          W_. (= _Zonochroa_ B. B. according to
+                          Villeneuve 1914).
+
+                       ll. Abdomen without macrochaetae; wing
+                          usually with a marginal streak and gray
+                          markings. Brazil. Hemilucilia B. B.
+
+[Illustration: 172. Left hand stigmata of the larvae of muscoidea. Third
+instar. (_a_) Lucilia caesar; (_b_) Calliphora vomitoria; (_c_) Stomoxys
+calcitrans; (_d_) Orthellia cornicina; (_e_) Pyrellia cadavarina;
+(_f_) Haematobia irritans; (_g_) Mesembrina mystacea; (_h_) Mesembrina
+meridiana; (_i_) Myospila meditabunda; (_j_) Mydaea urbana; (_k_)
+Polietes albolineata; (_l_) Polietes lardaria; (_m_) Morellia hortorum;
+(_n_) Hydrotaea dentipes; (_o_) Hebecnema umbratica; (_p_) H. vespertina;
+(_q_) Limnophora septemnotata; (_r_) Muscina stabulans. (_a_ and _b_)
+after MacGregor; (_d_) after Banks; all others after Portchinsky.
+Magnification varies. The relative distance to the median line is
+indicated in each figure.]
+
+
+SIPHONAPTERA. Fleas
+
+Adapted from a table published by Oudemans.
+
+a. Elongated fleas, with jointed (articulated) head, with combs
+    (ctenidia) on head and thorax; with long, oval, free-jointed
+    flagellum of the antenna (fig. 92d). Suborder FRACTICIPATA
+
+  b. With ctenidia in front of the antennae and on the genae (cheeks);
+      maxillae with acute apices; labial palpi five-segmented,
+      symmetrical; eyes poorly developed or wanting. On rodents.
+      HYSTRICHOPSYLLIDAE
+
+    c. Abdominal segments without ctenidia.
+
+      d. Post-tibial spines in pairs and not in a very close set row;
+          head with ctenidia. _Ctenophthalmus_ Kol.
+
+      dd. Post-tibial spines mostly single and in a close set row.
+          _Ctenopsyllus_ and _Leptopsyllus_. The last genus has recently
+          been erected for _L. musculi_, a widely distributed species
+          occurring on rats and mice.
+
+    cc. Abdominal segments with one or more ctenidia; post-tibial spines
+        in numerous, short, close-set transverse rows on posterior
+        border with about four spines in each row. _H. americana._
+        _Hystrichopsylla_ Taschenb.
+
+  bb. With only two pairs of subfrontal ctenidia; labial palpi
+      five-segmented, symmetrical; eyes vestigial or wanting. On bats.
+      (= ISCHNOPSYLLIDAE). NYCTERIDIPSYLLIDAE
+
+    With more or less blunt maxilla; all tibiae with notch; a single
+        antepygidial bristle; metepimeron without ctenidium. _N.
+        crosbyi_ from Missouri was found on bats. Rothschild suggests
+        that this is probably the same as _N. insignis_. (=
+        _Ischnopsyllus_ = _Ceratopsyllus_), _Nycteridiphilus_
+
+aa. Head not jointed, i.e. the segments coalescent, traces of the
+    segmentation still being visible in the presence of the vertex
+    tubercle, the falx (sickle-shaped process), and a suture. Suborder
+    INTEGRICIPITA
+
+  b. Flagellum of the antennae long and oval.
+
+    c. Usually elongate fleas, with a free-segmented flagellum of the
+        antenna; thorax not shorter than the head, longer than the first
+        tergite.
+
+      d. Genae of the head and the pronotum with ctenidia. NEOPSYLLIDAE
+
+        e. Labial palpi four or five-segmented; symmetrical; hind coxae
+            with patch of spines inside; row of six spatulate spines on
+            each side in front of the antennae. _C. ornate_ found on a
+            California mole. _Corypsylla_
+
+        ee. Labial palpi two-segmented, transparent, membranous. On
+            hares. _Spilopsyllus_ Baker
+
+      dd. No ctenidium on the head.
+
+        e. Pronotum with ctenidium. DOLICHOPSYLLIDAE
+
+          f. Labial palpi five-segmented, symmetrical.
+
+            g. Antepygidial bristles one to three; eyes present.
+
+              h. Inner side of hind coxae distally with a comb of minute
+                  teeth; falx present. On rodents and carnivores.
+                  _Odontopsyllus_ Baker
+
+              hh. Inner side of hind coxae without comb or teeth. Many
+                  North American species on rodents. CERATOPHYLLUS
+                  Curtis
+
+            gg. Antepygidial bristles five on each side; eyes absent;
+                suture white. _D. stylosus_ on rodents. _Dolichopsyllus_
+                Baker
+
+          ff. Labial palpi four or five-segmented; asymmetrical
+              (membranous behind), apex acute. _Hoplopsyllus anomalus_
+              found on Spermophiles in Colorado. HOPLOPSYLLIDAE
+
+        ee. Pronotum without ctenidium. _Anomiopsyllus californicus_ and
+            _nudatus_ on rodents. ANOMIOPSYLLIDAE
+
+    cc. Very short fleas; flagellum of the antenna with pseudo-segments
+        coalescent; thorax much shorter than the head and than the first
+        tergite. HECTOPSYLLIDAE
+
+      Flagellum of the antenna with six coalescent pseudo-segments;
+          maxilla blunt. The chigger on man (fig. 93). D. PENETRANS. (=
+          RHYNCHOPRION = SARCOPSYLLA) DERMATOPHILUS Guerin
+
+  bb. Flagellum short, round, free portion of the first segment shaped
+      like a mandolin.
+
+    c. Thorax not shorter than the head, longer than the first tergite;
+        flagellum either with free segments or in part with the segments
+        coalescent.
+
+      d. Head and pronotum with ctenidium; labial palpi asymmetrical.
+          ARCHAEOPSYLLIDAE
+
+        With four subfrontal, four genal, and one angular ctenidia.
+            Widely distributed. CTENOCEPHALUS Kol.
+
+        e. Head rounded in front (fig. 92a). Dog flea. C. CANIS
+
+        ee. Head long and flat (fig. 92b). Cat flea. C. FELIS
+
+      dd. Neither head nor pronotum with ctenidium. Labial palpi
+          asymmetrical, membranous behind. PULICIDAE
+
+        e. Mesosternite narrow, without internal rod-like thickening
+            from the insertion of the coxae upwards. Human flea, etc.
+            PULEX L.
+
+        ee. Mesosternite broad with a rod-like internal thickening from
+            the insertion of the coxae upwards (fig. 89). X.
+            (LOEMOPSYLLA) CHEOPIS, plague or rat flea. XENOPSYLLA
+
+    cc. Thorax much shorter than the head and than the first tergite.
+        ECHIDNOPHAGIDAE. E. GALLINACEA, the hen flea also attacks man
+        (fig. 96). (= ARGOPSYLLA = XESTOPSYLLA) ECHIDNOPHAGA Olliff.
+
+
+FOOTNOTES:
+
+[E] Adapted from Banks, Nuttall, Warburton, Stiles, _et al._
+
+[F] Dr. C. W. Stiles considers the species which is responsible for
+spotted fever distinct from the _venustus_ of Banks, separating it as
+follows:
+
+Goblet cells about 75 in the male or 105 in the female. Texas. _D.
+venustus._
+
+Goblet cells 157 in the male, or 120 in the female; stigmal plate shaped
+as shown in the figure (figs. 150 a, b). Montana, etc. D. ANDERSONI.
+
+[G] Professor C. R. Crosby who has been working upon certain capsids
+states that he and his assistant have been bitten by LYGUS PRATENSIS,
+the tarnished plant bug, by CHLAMYDATUS ASSOCIATUS and by ORTHOTYLUS
+FLAVOSPARSUS, though without serious results.
+
+[H] Species marked with an * are known to transmit malaria. Species
+found only in tropical North America and not known to carry malaria have
+been omitted from this table, but all found in the United States are
+included.
+
+[I] This table to the North American genera of the Tabanidae is adapted
+from one given by Miss Ricardo.
+
+[J] The classification of the Muscoidea as set forth by Schiner and
+other earlier writers has long been followed, although it is not
+satisfactory, being admittedly more or less artificial. Within the last
+two or three decades several schemes have been advanced, that of Brauer
+and Bergenstamm and of Girschner, with the modifications of Schnabl and
+Dziedzicki having obtained most favor in Europe. Townsend, in 1908,
+proposed a system which differs from Girschner's in some respects, but
+unfortunately it has not yet been published in sufficient detail to
+permit us to adopt it. From considerations of expediency we use here the
+arrangement given in Aldrich's Catalogue of North American Diptera,
+though we have drawn very freely upon Girschner's most excellent paper
+for taxonomic characters to separate the various groups.
+
+It may sometimes be found that a species does not agree in all the
+characters with the synopsis; in this case it must be placed in the
+group with which it has the most characters in common.
+
+[K] There are several genera of flies of the family _Cordyluridae_; (i.e.
+_Acalyptratae_) which might be placed with the _Anthomyiidae_ (i.e.
+_Calyptratae_), owing to the relatively large size of their squamae. As
+there is no single character which will satisfactorily separate all
+doubtful genera of these two groups we must arbitrarily fix the limits.
+In general those forms on the border line having a costal spine, or
+lower squama larger than the upper, or the lower surface of the
+scutellum more or less pubescent, or the eyes of the male nearly or
+quite contiguous, or the eyes hairy, or the frontal setae decussate in
+the female; or any combination of these characters may at once be placed
+with the _Anthomyiidae_. Those forms which lack these characteristics and
+have at least six abdominal segments (the first and second segments
+usually being more or less coalescent) are placed with the Acalyptrates.
+There are other acalyptrates with squamae of moderate size which have
+either no vibrissae, or have the subcosta either wholly lacking or
+coalescent in large part with R_1 or have spotted wings; they, therefore
+will not be confused with the calyptrates.
+
+[L] _Pachymyia_ Macq. is closely related to _Stomoxys_. It differs in
+having the arista rayed both above and below. _P. vexans_, Brazil.
+
+[M] The genus _Eudasyphora_ Town. has recently been erected to contain
+_D. lasiophthalma_.
+
+[N] _Nitellia_, usually included in this genus has the apical cell
+petiolate. _Apollenia_ Bezzi, has recently been separated from
+_Pollenia_ to contain the species _P. nudiuscula_. Both genera belong to
+the Eastern hemisphere.
+
+[O] The following three genera are not sufficiently well defined to
+place in this synopsis. In color and structural characters they are
+closely related to _Cynomyia_ from which they may be distinguished as
+follows. _Catapicephala_ Macq., represented by the species _C.
+splendens_ from Java, has the setae on the facial ridges rising to the
+base of the antennae and has median marginal macrochaetae on the
+abdominal segments two to four: _Blepharicnema_ Macq., represented by
+_B. splendens_ from Venezuela has bare genae, oral setae not
+ascending; tibiae villose; claws short in both sexes; _Sarconesia_
+Bigot with the species _S. chlorogaster_ from Chile, setose genae;
+legs slender, not villose; claws of the male elongate.
+
+[P] _Plinthomyia_ Rdi. and _Hemigymnochaeta_ Corti are related to
+_Ochromyia_, though too briefly described to place in the key.
+
+
+
+
+APPENDIX
+
+HYDROCYANIC ACID GAS AGAINST HOUSEHOLD INSECTS
+
+
+The following directions for fumigating with hydrocyanic acid
+gas are taken from Professor Herrick's circular published by the
+Cornell Reading Course:
+
+Hydrocyanic acid gas has been used successfully against household
+insects and will probably be used more and more in the future.
+It is particularly effective against bed-bugs, and cockroaches, but
+because _it is such a deadly poison it must be used very carefully_.
+
+The gas is generated from the salt potassium cyanid, by treating
+it with sulfuric acid diluted with water. Potassium cyanid is a
+most poisonous substance and the gas emanating from it is also
+deadly to most, if not all, forms of animal life. The greatest care
+must always be exercised in fumigating houses or rooms in buildings
+that are occupied. Before fumigation a house should be vacated.
+It is not necessary to move furniture or belongings except brass or
+nickel objects, which may be somewhat tarnished, and butter, milk,
+and other larder supplies that are likely to absorb gas. If the nickel
+and brass fixtures or objects are carefully covered with blankets
+they will usually be sufficiently protected.
+
+There may be danger in fumigating one house in a solid row of
+houses if there is a crack in the walls through which the gas may find
+its way. It also follows that the fumigation of one room in a house
+may endanger the occupants of an adjoining room if the walls between
+the two rooms are not perfectly tight. It is necessary to keep
+all these points in mind and to do the work deliberately and thoughtfully.
+The writer has fumigated a large college dormitory of 253
+rooms, once a year for several years, without the slightest accident
+of any kind. In order to fumigate this building about 340 pounds
+of cyanid and the same amount of sulfuric acid were used each time.
+In addition to this, the writer has fumigated single rooms and smaller
+houses with the gas. In one instance the generating jars were too
+small; the liquid boiled over and injured the floors and the rugs.
+Such an accident should be avoided by the use of large jars and by
+placing old rugs or a quantity of newspapers beneath the jars.
+
+
+THE PROPORTIONS OF INGREDIENTS
+
+Experiments and experience have shown that the potassium
+cyanid should be ninety-eight per cent pure in order to give satisfactory
+results. The purchaser should insist on the cyanid being of
+at least that purity, and it should be procurable at not more than
+forty cents per pound. The crude form of sulfuric acid may be used.
+It is a thickish, brown liquid and should not cost more than four or
+five cents a pound. If a room is made tight, one ounce of cyanid for
+every one hundred cubic feet of space has been shown to be sufficient.
+It is combined with the acid and water in the following proportions:
+
+  Potassium cyanid                       1 ounce
+  Commercial sulfuric acid               1 fluid ounce
+  Water                                  3 fluid ounces
+
+
+A SINGLE ROOM AS AN EXAMPLE
+
+Suppose a room to be 12 by 15 by 8 feet. It will contain 12 x 15 x 8, or
+1440 cubic feet. For convenience the writer always works on the basis of
+complete hundreds; in this case he would work on the basis of 1500 cubic
+feet, and thus be sure to have enough. The foregoing room, then, would
+require 15 ounces of cyanid, 15 ounces of sulfuric acid, and 45 ounces
+of water. The room should be made as tight as possible by stopping all
+the larger openings, such as fireplaces and chimney flues, with old rags
+or blankets. Cracks about windows or in other places should be sealed
+with narrow strips of newspaper well soaked in water. Strips of
+newspaper two or three inches wide that have been thoroughly soaked in
+water may be applied quickly and effectively over the cracks around the
+window sash and elsewhere. Such strips will stick closely for several
+hours and may be easily removed at the conclusion of the work.
+
+While the room is being made tight, the ingredients should be measured
+according to the formula already given. The water should be measured and
+_poured first_ into a stone jar for holding at least two gallons. The
+jar should be placed in the middle of the room, with an old rug or
+several newspapers under it in order to protect the floor.
+
+The required amount of sulfuric acid should then be poured rather slowly
+into the water. _This process must never be reversed; that is, the acid
+must never be poured into the jar first._ The cyanid should be weighed
+and put into a paper bag beside the jar. All hats, coats, or other
+articles that will be needed before the work is over should be removed
+from the room. When everything is ready the operator should drop the bag
+of cyanid gently into the jar, holding his breath, and should walk
+quickly out of the room. The steam-like gas does not rise immediately
+under these conditions, and ample time is given for the operator to walk
+out and shut the door. If preferred, however, the paper bag may be
+suspended by a string passing through a screw eye in the ceiling and
+then through the keyhole of the door. In this case the bag may be
+lowered from the outside after the operator has left the room and closed
+the door.
+
+The writer has most often started the fumigation toward evening and left
+it going all night, opening the doors in the morning. The work can be
+done, however, at any time during the day and should extend over a
+period of five or six hours at least. It is said that better results
+will be obtained in a temperature of 70^o F., or above, than at a lower
+degree.
+
+At the close of the operation the windows and doors may be opened from
+the outside. In the course of two or three hours the gas should be
+dissipated enough to allow a person to enter the room without danger.
+The odor of the gas is like that of peach kernels and is easily
+recognized. The room should not be occupied until the odor has
+disappeared.
+
+
+FUMIGATING A LARGE HOUSE
+
+The fumigation of a large house is merely a repetition, in each room and
+hall, of the operations already described for a single room. All the
+rooms should be made tight, and the proper quantities of water and
+sulfuric acid should be measured and poured into jars placed in each
+room with the cyanid in bags besides the jars. When all is ready, the
+operator should _go to the top floor and work downward_ because the gas
+is lighter than air and tends to rise.
+
+
+PRECAUTIONS
+
+The cyanid should be broken up into small pieces not larger than small
+eggs. This can best be done on a cement or brick pavement. It would be
+advantageous to wear gloves in order to protect the hands, although the
+writer has broken many pounds of cyanid without any protection on the
+hands. Wash the hands thoroughly at frequent intervals in order to
+remove the cyanid.
+
+The operations of the work must be carried out according to directions.
+
+The work should be done by a calm, thoughtful and careful person--best
+by one who has had some experience.
+
+Conspicuous notices of what has been done should be placed on the doors,
+and the doors should be locked so that no one can stray into the rooms.
+
+The gas is lighter than air, therefore one should always begin in the
+rooms at the top of the house and work down.
+
+After fumigation is over the contents of the jar should be emptied into
+the sewer or some other safe place. The jars should be washed thoroughly
+before they are used again.
+
+_It must be remembered that cyanid is a deadly poison_; but it is very
+efficient against household insects, if carefully used, and is not
+particularly dangerous when properly handled.
+
+
+LESIONS PRODUCED BY THE BITE OF THE BLACK-FLY
+
+While this text was in press there came to hand an important paper
+presenting a phase of the subject of black fly injury so different from
+others heretofore given that we deem it expedient to reproduce here the
+author's summary. The paper was published in _The Journal of Cutaneous
+Diseases_, for November and December, 1914, under the title of "A
+Clinical, Pathological and Experimental Study of the Lesions Produced by
+the Bite of the Black Fly (_Simulium venustum_)," by Dr. John Hinchman
+Stokes, of the University of Michigan.
+
+
+RESUME AND DISCUSSION OF EXPERIMENTAL FINDINGS
+
+The principal positive result of the work has been the experimental
+reproduction of the lesion produced by the black-fly in characteristic
+histological detail by the use of preserved flies. The experimental
+lesions not only reproduced the pathological pictures, but followed a
+clinical course, which in local symptomatology especially, tallied
+closely with that of the bite. This the writer interprets as
+satisfactory evidence that the lesion is not produced by any living
+infective agent. The experiments performed do not identify the nature of
+the toxic agent. Tentatively they seem to bring out, however, the
+following characteristics.
+
+1. The product of alcoholic extraction of flies do not contain the toxic
+agent.
+
+2. The toxic agent is not inactivated by alcohol.
+
+3. The toxic agent is not destroyed by drying fixed flies.
+
+4. The toxic agent is not affected by glycerin, but is, if anything,
+more active in pastes made from the ground fly and glycerin, than in the
+ground flies as such.
+
+5. The toxic agent is rendered inactive or destroyed by hydrochloric
+acid in a concentration of 0.25%.
+
+6. The toxic agent is most abundant in the region of the anatomical
+structures connected with the biting and salivary apparatus (head and
+thorax).
+
+7. The toxic agent is not affected by a 0.5% solution of sodium
+bicarbonate.
+
+8. The toxic agent is not affected by exposure to dry heat at 100^o C.
+for two hours.
+
+9. The toxic agent is destroyed or rendered inactive in alkaline
+solution by a typical hydrolytic ferment, pancreatin.
+
+10. Incomplete experimental evidence suggests that the activity of the
+toxic agent may be heightened by a possible lytic action of the blood
+serum of a sensitive individual, and that the sensitive serum itself may
+contain the toxic agent in solution.
+
+These results, as far as they go (omitting No. 10), accord with Langer's
+except on the point of alcoholic solubility and the effect of acids. The
+actual nature of the toxic agent in the black-fly is left a matter of
+speculation.
+
+The following working theories have suggested themselves to the writer.
+First, the toxin may be, as Langer believes in the case of the bee, an
+alkaloidal base, toxic as such, and neutralized after injection by
+antibodies produced for the occasion by the body. In such a case the
+view that a partial local fixation of the toxin occurs, which prevents
+its immediate diffusion, is acceptable. Through chemotactic action,
+special cells capable of breaking up the toxin into harmless elements
+are attracted to the scene. Their function may be, on the other hand, to
+neutralize directly, not by lysis. This would explain the role of the
+eosinophiles in the black-fly lesion. If their activities be essential
+to the destruction or neutralization of the toxin, one would expect them
+to be most numerous where there was least reaction. This would be at the
+site of a bite in an immune individual. A point of special interest for
+further investigation, would be the study of such a lesion.
+
+Second, it is conceivable that the injected saliva of the fly does not
+contain an agent toxic as such. It is possible, that like many foreign
+proteins, it only becomes toxic when broken down. The completeness and
+rapidity of the breaking down depends on the number of eosinophiles
+present. In such a case immunity should again be marked by intense
+eosinophilia.
+
+[Illustration: 173. Fifth day mature lesion. Lower power drawing showing
+papillary oedema and infiltrate in the region of the puncture. After Dr.
+J. H. Stokes]
+
+Third, lytic agents in the blood serum may play the chief role in the
+liberation of the toxic agent from its non-toxic combination. An immune
+individual would then be one whose immunity was not the positive one of
+antibody formation, but the negative immunity of failure to metabolize.
+An immune lesion in such a case might be conceived as presenting no
+eosinophilia, since no toxin is liberated. If the liberation of the
+toxin is dependent upon lytic agents present in the serum rather than in
+any cellular elements, a rational explanation would be available for the
+apparent results (subject to confirmation) of the experiment with
+sensitive and immune sera. In this experiment it will be recalled that
+the sensitive serum seemed to bring out the toxicity of the ground
+flies, and the serum itself seemed even to contain some of the dissolved
+or liberated toxin. The slowness with which a lesion develops in the
+case of the black-fly bite supports the view of the initial lack of
+toxicity of the injected material. The entire absence of early
+subjective symptoms, such as pain, burning, etc., is further evidence
+for this view. It would appear as if no reaction occurred until lysis of
+an originally non-toxic substance had begun. Regarding the toxin itself
+as the chemotactic agent which attracts eosinophiles, its liberation in
+the lytic process and diffusion through the blood stream attracts the
+cells in question to the point at which it is being liberated. Arriving
+upon the scene, these cells assist in its neutralization.
+
+The last view presented is the one to which the author inclines as the
+one which most adequately explains the phenomena.
+
+A fourth view is that the initial injection of a foreign protein by the
+fly (i.e., with the first bite) sensitizes the body to that protein. Its
+subsequent injection at any point in the skin gives rise to a local
+expression of systematic sensitization. Such local sensitization
+reactions have been described by Arthus and Breton, by Hamburger and
+Pollack and by Cowie. The description of such a lesion given by the
+first named authors, in the rabbit, however, does not suggest,
+histopathologically at least, a strong resemblance to that of the
+black-fly. Such an explanation of many insect urticariae deserves further
+investigation, however, and may align them under cutaneous expressions
+of anaphylaxis to a foreign protein injected by the insect. Depending on
+the chemical nature of the protein injected, a specific chemotactic
+reaction like eosinophilia may or may not occur. Viewed in this light
+the development of immunity to insect bites assumes a place in the
+larger problem of anaphylaxis.
+
+[Illustration: 174. Experimental lesion produced from alcohol-fixed
+flies, dried and ground into a paste with glycerin. After Dr. J. H.
+Stokes]
+
+
+SUMMARY
+
+In order to bring the results of the foregoing studies together, the
+author appends the following resume of the clinical data presented in
+the first paper.
+
+The black-fly, _Simulium venustum_, inflicts a painless bite, with
+ecchymosis and haemorrhage at the site of puncture. A papulo-vesicular
+lesion upon an urticarial base slowly develops, the full course of the
+lesion occupying several days to several weeks. Marked differences in
+individual reaction occur, but the typical course involves four stages.
+These are, in chronological order, the papular stage, the vesicular or
+pseudovesicular, the mature vesico-papular or weeping papular stage and
+the stage of involution terminating in a scar. The papule develops in
+from 3 to 24 hours. The early pseudovesicle develops in 24 to 48 hours.
+The mature vesico-papular lesion develops by the third to fifth day and
+may last from a few days to three weeks. Involution is marked by
+cessation of oozing, subsidence of the papule and scar-like changes at
+the site of the lesion. The symptoms accompanying this cycle consist of
+severe localized or diffused pruritus, with some heat and burning in the
+earlier stages if the oedema is marked. The pruritus appears with the
+pseudovesicular stage and exhibits extraordinary persistence and a
+marked tendency to periodic spontaneous exacerbation. The flies tend to
+group their bites and confluence of the developing lesions in such cases
+may result in extensive oedema with the formation of oozing and
+crusted plaques. A special tendency on the part of the flies to attack
+the skin about the cheeks, eyes and the neck along the hair line and
+behind the ears, is noted. In these sites inflammation and oedema may
+be extreme.
+
+A distinctive satellite adenopathy of the cervical glands develops in
+the majority of susceptible persons within 48 hours after being bitten
+in the typical sites. This adenopathy is marked, discrete and painful,
+the glands often exquisitely tender on pressure. It subsides without
+suppuration.
+
+Immunity may be developed to all except the earliest manifestations, by
+repeated exposures. Such an immunity in natives of an infested locality
+is usually highly developed. There are also apparently seasonal
+variations in the virulence of the fly and variations in the reaction of
+the same individual to different bites.
+
+Constitutional effects were not observed but have been reported.
+
+
+
+
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+
+---- 1914. Insects injurious to the household and annoying to man. 8vo.
+   New York, Macmillan Co. (xvii + 470).
+
+HEWITT, C. G. 1910. The house-fly. A study of its structure,
+   development, bionomics, and economy. 8vo. Manchester Univ. Press.
+   (xiv + 196 p.).
+
+---- 1912. _Fannia_ (_Homalomyia_) _canicularis_ Linn. and _F. scalaris_
+   Fab. Parasitology, v. p. 161-174.
+
+HEYMONS, R. 1901. Biologische Beobachtungen an asiatischen Solifugen,
+   nebst Beitrage zur Systematik derselben. Abl. Ak. Berlin, 1901, Anh.
+   i, 1-65 p.
+
+HIGGINS, F. W. 1891. Dipterous larvae vomited by a child. Insect Life,
+   Washington. iii, p. 396-397.
+
+HINDLE, E. 1911 a. The relapsing fever of tropical Africa. A Review.
+   Parasitology, iv, p. 183-203.
+
+---- 1911 b. On the life cycle of _Spirochaeta gallinarum_. ibid., iv.
+   p. 463-477.
+
+HINDLE, E. and MERRIMAN, G. 1914. The range of flight of _Musca
+   domestica_. Journ. of Hygiene, xiv. p. 23-45.
+
+HINE, J. S. 1903. Tabanidae of Ohio. Papers Ohio Acad. Sci. No. 5, 55 p.
+
+---- 1906. Habits and life-histories of some flies of the family
+   Tabanidae. U. S. Dept. Agric. Bur. Ent. tech. bul. 12, p. 19-38.
+
+---- 1907. Second report upon the horse-flies of Louisiana. La. Stat.
+   Exp. Bul. 93, p. 1-59.
+
+HODGE, C. F. 1910. A practical point in the study of the typhoid, or
+   filth-fly. Nature Study Review, vi, p. 195-199.
+
+---- 1913. The distance house-flies, blue-bottles, and stable flies may
+   travel over water. Science, n. s. xxxviii, p. 513.
+
+HONEIJ, J. A. and PARKER, R. R. 1914. Leprosy: flies in relation to the
+   transmission of the disease. Journ. Med. Research, Boston, xxx, p.
+   127-130.
+
+HOOKER, W. A. 1908 a. Life history, habits, and methods of study of the
+   Ixodoidea. Jour. Econ. Ent. i, p. 34-51.
+
+---- 1908 b. A review of the present knowledge of the role of ticks in
+   the transmission of disease. ibid., i, p. 65-76.
+
+HOPE, F. W. 1837. On insects and their larvae occasionally found in the
+   human body. Trans. Ent. Soc., London, ii, p. 256-271.
+
+HOUGH, G. DE N. 1899 a. Synopsis of the Calliphorinae of the United
+   States. Zoological Bulletin, ii, p. 283-290.
+
+---- 1899 b. Some Muscinae of North America, Biological Bulletin i, p.
+   19-33.
+
+---- 1899 c. Some North American Genera of Calliphorinae. Entom. News,
+   x, p. 62-66.
+
+HOVARTH, G. 1912. Revision of the American Cimicidae. Ann. Mus. Nat.
+   Hungarici, x, p. 257-262.
+
+HOWARD, C. W. 1908. A list of the ticks of South Africa, with
+   descriptions and keys to all the forms known. Ann. Transvaal Mus. 1,
+   p. 73-170.
+
+HOWARD, C. W. and CLARK, P. F. 1912. Experiments on insect transmission
+   of the virus of poliomyelitis. Journ. Exper. Med. xvi, p. 805-859.
+
+HOWARD, L. O. 1899. Spider bites and kissing bugs. Pop. Sci. Mo. lv, p.
+   31-42.
+
+---- 1900. A contribution to the study of the insect fauna of human
+   excrement. Proc. Wash. Acad. Sci. ii, p. 541-604.
+
+---- 1901. Mosquitoes, how they live, how they carry disease, how they
+   are classified, how they may be destroyed. 8vo. New York, Doubleday,
+   Page & Co. (xv + 241 p.)
+
+---- 1909. Economic loss to the people of the United States, through
+   insects that carry disease. U. S. Dept. Agric. Bur. of Ent. Bul. 78,
+   p. 1-40.
+
+HOWARD, L. O., DYAR, H. G. and KNAB, F. 1913-. The mosquitoes of North
+   and Central America and the West Indies. Vol. I. A general
+   consideration of mosquitoes, their habits, and their relations to the
+   human species. 4^o. Carnegie Institution of Washington (vii + 520
+   p.).
+
+HOWARD, L. O. and MARLATT, C. L. 1902. The principal household insects
+   of the United States. U. S. Dept. Agric., Bur. Ent. Bul. 4.
+
+HUEBNER, W. 1907. Ueber das Pfeilgift der Kalahari. Arch. exper. Path.
+   und Pharm., lvii, p. 358-366.
+
+HUNTER, S. J. 1913. Pellagra and the sand-fly. Jour. econ. Ent. vi, p.
+   96-99.
+
+HUNTER, W. D. 1913. American interest in medical entomology. Jour. econ.
+   Ent. vi, p. 27-39.
+
+HUNTER, W. D. and BISHOPP, F. C. 1910. Some of the more important ticks
+   of the United States. U. S. Dept. Agric. Yearbook 1910, p. 219-230,
+   pls. xv-xvi.
+
+---- 1911. The Rocky Mountain spotted fever tick. With special reference
+   to the problem of its control in the Bitter Root Valley in Montana.
+   U. S. Dept. Agric., Bur. Ent. Bul. 105, p. 1-47.
+
+HUTCHISON, R. H. 1914. The migratory habit of housefly larvae as
+   indicating a favorable remedial measure. An account of progress. U.
+   S. Dept. Agric., Bul. 14, p. 1-11.
+
+JENNINGS, A. H. 1914. Summary of two years' study of insects in relation
+   to pellagra. Journ. of Parasitology, i, p. 10-21.
+
+JENNINGS, A. H. and KING, W. V. 1913. One of the possible factors in the
+   causation of pellagra. Journ. Amer. Med. Assoc., lx, p. 271-274.
+
+JEPSON, F. P. 1909. Notes on colouring flies for purposes of
+   identification. Rep't to the Local Gov't Board on Publ. Health, n. s.
+   16, p. 4-9.
+
+JOHANNSEN, O. A. 1903. Aquatic Nematocerous Diptera. N. Y. State Mus.
+   Bul., 68, p. 328-448, pls. 32-50.
+
+---- 1905. Aquatic Nematocerous Diptera II. (Chironomidae). ibid. 86, p.
+   76-330, pls. 16-37.
+
+---- 1908. North America Chironomidae. ibid., 124, p. 264-285.
+
+---- 1911. The typhoid fly and its allies. Maine Agric. Exp. Sta. Bul.,
+   401, p. 1-7.
+
+---- 1911. Simulium and pellagra. Insect Notes for 1910. Maine Agr.
+   Exper. Station. Bul. 187, p. 4.
+
+KELLOGG, V. L. 1915. Spider poison. Jour. of Parasitology, i, p. 107+
+
+KELLY, H. A. 1907. Walter Reed and yellow fever. 8vo. New York, McClure,
+   Phillips & Co. (xix + 310 p.).
+
+KEPHART, CORNELIA F. 1914. The poison glands of the larva of the
+   browntail moth (Euproctis chrysorrhoea Linn.). Journ. Parasit., i,
+   p.
+
+KIEFFER, J. J. 1906. Chironomidae. Genera Insectorum. Fasc. 42, p. 1-78.
+
+---- 1913. Nouv. etude sur les Chironomides de l'Indien Museum de
+   Calcutta. Records of the Indian Mus., ix, p. 119-197.
+
+KING, A. F. A. 1883. Insects and disease--mosquitoes and malaria. Pop.
+   Sci. Mo. xxiii, p. 644-658.
+
+KIRKLAND, A. H. 1907. Second annual report of the Superintendent for
+   suppressing the gypsy and browntail moths. 8vo. Boston. 170 p.
+
+KLEINE, E. 1909. Postive Infektionsversuche mit _Trypanosoma brucei_
+   durch _Glossina palpalis._ Deutsche med. Wochenschr., xxxv, p.
+   469-470.
+
+   Weitere wissenschaftliche Beobachtungen uber die Entwicklung von
+      Trypanosomen in Glossinen. ibid. p. 924-925.
+
+   Weitere Untersuchungen uber die Aetiologie der Schlafkrankheit. ibid.,
+      p. 1257-1260.
+
+   Weitere Beobachtungen uber Tsetsefliegen und Trypanosomen. ibid., p.
+      1956-1958.
+
+KLING, C. and LEVADITI, C. 1913. Etudes sur la poliomyelite aigue
+   epidemique. Ann. Inst. Pasteur, xxvii, p. 718-749, 739-855.
+
+KNAB, F. 1912. Unconsidered factors in disease-transmission by
+   blood-sucking insects. Journ. Econ. Ent., v, p. 196-200.
+
+---- 1913 a. The species of Anopheles that transmit human malaria. Amer.
+   Journ. Trop. Dis. and Preventive Med., i, p. 24-43.
+
+---- 1913 b. Anopheles and malaria. ibid., i, p. 217.
+
+---- 1913 c. The life history of _Dermatobia hominis_. ibid., i, p.
+   464-468.
+
+KNAB, F. See Howard, Dyar, and Knab.
+
+KOBERT, R. 1893. Lehrbuch der Intoxikationen. 4^o. Stuttgart, Enke. (xxii
+   + 816 p.). 2d ed. in 2 vols., 1906.
+
+---- 1901. Beitrage zur Kenntniss der Giftspinnen. 8^o. Stuttgart, Enke.
+   (viii + 191 p.).
+
+KOLBE, H. J. 1894. Der Pfeilgiftkafer der Kalahari-Wuste, _Diamphidia
+   simplex_. Stett. Ent. Zeitg., iv, p. 79-86.
+
+KRAUSE, M. 1907. Untersuchungen uber Pfeilgifte aus unseren
+   africanischen Kolonien. Verhand. deutsche Kolonien kong. 1905. p.
+   264-288.
+
+LALLIER, P. 1897. Etude sur la myase du tube digestif chez l'homme.
+   Thesis, Paris, 8^o. 120 p.
+
+LANGER, J. 1897. Ueber das Gift unserer Honigbiene. Archiv. exper. Path.
+   und Pharm., xxxviii, p. 381-396.
+
+LAVINDER, C. H. 1911. Pellagra: a precis. U. S. Publ. Health Service
+   Bul. 48, 37 p.
+
+LEIDY, J. 1847. History and anatomy of the hemipterous genus
+   _Belostoma_. Journ. Acad. Philad. (2), i, p. 57-67.
+
+LEIPER, R. T. 1907. The etiology and prophylaxis of dracontiasis.
+   British Med. Journ. 1907, p. 129-132.
+
+LEISHMAN, W. B. 1910 a. Observations on the mechanism of infection in
+   tick fever and on the hereditary transmission of _Spirochaeta duttoni_
+   in the tick. Trans. Soc. Trop. Med. Hyg., iii, p. 77-95. Abstr. in
+   Bul. Inst. Pasteur, viii, p. 312-313.
+
+---- 1910 b. On the hereditary transmission and mechanism of infection
+   in tick fever and on the hereditary transmission of _Spirochaeta
+   duttoni_ in the tick. Lancet., clxxvii, p. 11.
+
+LINNELL, R. McC. 1914. Notes on a case of death following the sting of a
+   scorpion. Lancet, 1914, p. 1608-1609.
+
+LIVINGSTONE, D. 1857. Missionary travels and researches in South Africa.
+
+LUCAS, H. 1843. (note) _Latrodectus malmignatus_ Bul. Soc. Ent., France,
+   1843, p. viii.
+
+LUDLOW, C. S. 1914. Disease bearing mosquitoes of North and Central
+   America, the West Indies and the Philippine Islands. War Dept.,
+   Office of Surgeon General. Bul. No. 4, 1-96.
+
+LUGGER, 1896. Insects injurious in 1896. Agr. Exp. Sta. Bul. 48. p. 33
+   to 270.
+
+MacCALLUM, W. C. 1898. On the haematozoan infection of birds. Journ. Exp.
+   Med. iii, p. 117.
+
+MacGREGOR, M. E. 1914. The posterior stigmata of dipterous larvae as a
+   diagnostic character. Parasitology, vii, p. 176-188.
+
+MacLOSKIE, G. 1888. The poison apparatus of the mosquito. Amer.
+   Naturalist, xxii, p. 884-888.
+
+MALLOCH, J. P. 1913. American black-flies or Buffalo gnats. U. S. Dept.
+   Agric. Bur. Ent. Tech. Bul. 26, p. 1-72.
+
+---- 1914. Notes on North American Diptera. Bul. Illinois State Lab.
+   Nat. Hist., x, p. 213-243.
+
+MANSON, P. 1911. Tropical diseases: a manual of the diseases of warm
+   climates. 8^o. London, Cassell & Co. (xx + 876 p.). 4 ed. (1907).
+   Reprinted.
+
+MARCHOUX, E. and COUVY, L. 1913. Argas et spirochaetes (1 memoire). Les
+   granules de Leishman. Ann. Inst. Pasteur, xxvii, p. 450-480. 2
+   memoire. Le virus chez l'acarien. ibid. p. 620-643.
+
+MARCHOUX, E. and SELIMBENI, A. 1903. La spirillose des poules. Ann.
+   Inst. Pasteur, xvii, p. 569-580.
+
+MARCHOUX, E. and SIMOND, P. L. 1905. Etudes sur la fievre jaune. Ann.
+   Inst. Pasteur, xx, pp. 16-40, 104-148, 161-205.
+
+MARLATT, C. L. 1902. (See Howard, L. O. and Marlatt, C. L.)
+
+---- 1907. The bed-bug (_Cimex lectularius_ L.) U. S. Dept. Agric., Bur.
+   Ent., Circ. No. 47, revised ed., 8 pp.
+
+MARTIN, G. LEBOEUF, and ROUBAUD. 1909. Rapport de la mission d'etudes de
+   la maladie du sommeil au Congo francais. 4^o. Paris, Masson & Cie.
+   (vi + 722 p., 8 pls. and map.).
+
+MAVER, MARIA B. 1911. Transmission of spotted fever by other than
+   Montana and Idaho ticks. Journ. Infec. Dis., viii, p. 322-326.
+
+McCLINTIC, T. B. 1912. Investigations of and tick eradications in Rocky
+   Mountain spotted fever. Publ. Health Repts., Washington, xxvii, p.
+   732-760.
+
+MECKEL, H. 1847. Uber schwarzes Pigment in der Milz und im Blute einer
+   Geisteskranken. Allgem. Zeitschr. f. Psychiatrie, iv, p. 198-226.
+
+MEGNI, P. 1906. Les insectes buveurs de sang. 12mo. Paris, Rudeval. (150
+   p.).
+
+MELNIKOFF, N. 1869. Ueber die Jugendzustande der _Taenia cucumerina_.
+   Arch. f. Naturg., xxxv, p. 62-70.
+
+MENSE, C. 1913. Handbuch der Tropenkrankheiten. 1 Band. 4^o. Leipzig,
+   Barth (xv + 295 p.) Entomological parts by A. Eysell, and by Doerr
+   and Russ.
+
+MINCHIN, E. A. 1912. An introduction to the study of the Protozoa, with
+   special reference to the parasitic forms. 8^o. London. Arnold (xi +
+   517 p.).
+
+MITCHELL, EVELYN G. 1907. Mosquito life. 8vo. New York, Putmans. (xxii +
+   281 p.).
+
+MITZMAIN, M. B. 1910. General observations on the bionomics of the
+   rodent and human flies. U. S. Publ. Health Service. Bul., 38, p.
+   1-34.
+
+---- 1912. The role of _Stomoxys calcitrans_ in the transmission of
+   _Trypanosoma evansi_. Philippine Journ. Sci., vii, p. 475-519, 5 pls.
+
+---- 1913 a. The biology of _Tabanus striatus_ Fabricius, the horsefly
+   of the Philippines. ibid., vii, B. p. 197-221.
+
+---- 1913 b. The mechanical transmission of surra. ibid., viii, sec. B.,
+   p. 223-229.
+
+---- 1914 a. Experimental insect transmission of anthrax. U. S. Public
+   Health Repts. xxix, p. 75-77.
+
+---- 1914 b. I. Collected studies on the insect transmission of
+   _Trypanosoma evansi_. II. Summary of experiments in the transmission
+   of anthrax by biting flies. U. S. Pub. Health Service, Hyg. Lab.
+   Bul., 94, p. 1-48.
+
+MIYAKE, H. and SCRIBA, J. 1893. Vorlaufige Mitteilung uber einen neuen
+   Parasit des Menschen. Berl. klin. Wochenschr., xxx, p. 374.
+
+MOLLERS, B. 1907. Experimentelle Studien uber die Uebertragung des
+   Ruckfallfiebers durch Zecken. Zeitschr. fur Hyg. u.
+   Infektionskrankheiten, lviii, p. 277-286.
+
+MOTE, D. C. 1914. The cheese-skipper (_Piophila casei_). Ohio Naturalist
+   xiv, p. 309-310.
+
+NEIVA, A. 1910. Beitrage zur Biologie der _Conorhinus megistus_ Burm.
+   Memorias de Institute Oswaldo Cruz., ii, p. 206-212.
+
+NEVEU-LEMAIRE, M. 1907. Un nouveau cas de parasitisme accidental d'un
+   myriapode dans le tube digestif de l'homme, C. R. Soc. der Biol.,
+   lxiii p. 305-308.
+
+---- 1908. Precis de parasitologie humaine. 8vo. Paris, Rudeval. (v +
+   712 p.).
+
+NEWSTEAD, R. 1911. The papataci flies (Phlebotomus) of the Maltese
+   Islands. Bul. of Ent. Research, ii, p. 47-78, pls. 1-3.
+
+NICOLL, W. 1911. On the part played by flies in the disposal of the eggs
+   of parasitic worms. Repts. to the Local Gov't. Board on Publ. Health
+   and Med. Subjects, n. s. No. 53, p. 13-30.
+
+NICOLLE, C. 1910, Recherches experimentales sur la typhus exanthematique
+   entreprises a l'Institut Pasteur de Tunis pendant l'annee 1909. Ann.
+   Inst. Pasteur, xxiv, p. 243-275.
+
+---- 1911. Recherches experimentales sur la typhus exanthematique
+   entreprises a l'Institut Pasteur de Tunis pendant l'annee 1910.
+   ibid., xxv, p. 1-55, 97-154.
+
+NICOLLE, C., BLAIZOT, A., and CONSEIL, E. 1912 a. Etiologie de la fievre
+   recurrente. Son mode de transmission par le pou. C. R. Acad. Sci.,
+   cliv, p. 1636-1638.
+
+---- 1912 b. Conditions de transmission de la fievre recurrente par le
+   pou. ibid., clv., p. 481-484.
+
+NICOLLE, C. and CATOUILLARD, G. 1905. Sur le venin d'un scorpion commun
+   de Tunisie (_Heterometrus maurus_). C. R. Soc. Biol. lviii: p.
+   100-102.
+
+NOE, G. 1901. Sul ciclo evolutivo della _Filaria bancrofti_ e delta
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+
+NORMAN, W. W. 1896. The effect of the poison of centipedes. Trans. Texas
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+
+NUTTALL, G. H. F. 1899. On the role of insects, arachnids, and myriapods
+   as carriers in the spread of bacterial and parasitic diseases of man
+   and animals. Johns Hopkins Hosp. Repts., viii, 154 p., 3 pls.
+
+---- 1908 a. On the behavior of Spirochaetae in _Acanthia lectularia_.
+   Parasitology, i, p. 143-151.
+
+---- 1908 b. The transmission of _Trypanosoma lewisi_ by fleas and lice.
+   ibid., i, p. 296-301.
+
+---- 1908 c. The Ixodoidea or ticks, spirochaetosis in man and animals,
+   piroplasmosis. Journ. Roy. Inst. Publ. Health, xvi, p. 385-403,
+   449-464, 513-526.
+
+---- 1914. Tick paralysis in man and animals. Parasitology, vii, p.
+   95-104.
+
+NUTTALL, G. H. F. and JEPSON, F. P. 1909. The part played by _Musca
+   domestica_ and allied (non-biting) flies in the spread of infective
+   diseases. A summary of our present knowledge. Rept. to the Local
+   Gov't Board on Publ. Health and Med. Subjects, n. s. 16, p. 13-41.
+
+NUTTALL, G. H. F. and SHIPLEY, E. A. 1901-03. Studies in relation to
+   malaria. The structure and biology of Anopheles. Journ. Hyg., vols.
+   i, ii, and iii.
+
+ORTH, J. 1910. Ueber die Beziehungungen der Haarsackmilbe zu
+   Krebsbildungen in der Mamma. Berliner klin. Wochenschr., xlvii, p.
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+
+OSBORN, HERBERT. 1896. Insects affecting domestic animals. U. S. Dept.
+   Agric., Bur. of Ent. Bul., 5, n. s., 302 p.
+
+---- 1902. Poisonous insects. Article in Reference Handbook. Med. Sci.,
+   v, p. 158-169.
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+   Jour. i. p. 556.
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+
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+PETROVSKAIA, MARIA. 1910. Sur les myases produites chez l'homme par les
+   Oestrides (Gastrophilus et Rhinoestrus). These, Fac. de medecine,
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+
+PETTIT, A. and KROHN, A. 1905. Sur la structure des glandes salivaires
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+
+---- 1912. Effets physiologiques du venin de la Mygale de Haiti, le
+   _Phormictopus cancerides_ Pocock. Effets physiologiques du venin de
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+
+PORTSCHINSKY, I. A. 1908. _Rhinoestrus purpureus_, a parasite of
+   horses which deposits its larvae in the eyes of man. Mss. transl. by
+   Miss S. L. Weissman, in library of Ent. Dept., Cornell University.
+
+---- 1910. Biology of _Stomoxys calcitrans_ and other coprophagous
+   flies. Monograph in Russian. Mss. summarized transl. by Miss S. L.
+   Weissman, in Library of Ent. Dept., C. U.
+
+---- 1911. _Gastrophilus intestinalis_. Mss. transl. by Miss S. L.
+   Weissman, in library of Ent. Dept., C. U.
+
+---- 1913 a. The sheep gad-fly, _Oestrus ovis_, its life, habits,
+   methods of combating it, and its relation to man. Russian. Mss.
+   summarized trans. by Miss S. L. Weissman, in library of Ent. Dept.,
+   C. U.
+
+---- 1913 b. _Muscina stabulans_. A monograph in Russian. Mss., trans.
+   by J. Millman, in library of Ent. Dept., Cornell Univ.
+
+PROWAZEK, S. 1905. Studien uber Saugetiertrypanosomen. Arb. aus dem
+   kais. Gesundheitsamte xxii, p. 351-395.
+
+PUSEY, W. A. 1911. The principles and practice of dermatology. 2 ed,
+   8vo. Appleton & Co. (1079 p.)
+
+RABINOWITSCH, L. and KEMPNER, W. 1899. Beitrag zur Kentniss der
+   Blutparasiten, speciell der Ratten trypanosomen. Zeitschr. f. Hyg.
+   xxx, p. 251-291.
+
+RANSOM, B. H. 1904. An account of the tape worms of the genus
+   _Hymenolepis_ parasitic in man. Bul. No. 18, Hyg. Lab., U. S. Pub.
+   Health and Mar.-Hosp. Serv., Wash., p. 1-138.
+
+---- 1911. The life history of a parasitic nematode, _Hebronema muscae_.
+   Science n. s. xxxiv, p. 690-692.
+
+---- 1913. The life history of _Habronema muscae_, (Carter), a parasite
+   of the horse transmitted by the house-fly. U. S. Dept. Agric. Bur.
+   Animal, Ind. Bul. 163, p. 1-36.
+
+REAUMUR, R. A. F. DE. 1738. Memoires pour servir a l'histoirie des
+   insectes. Histoire des cousins, iv, p. 573-636.
+
+REED, WALTER. 1900. The etiology of yellow fever. Philadelphia Med.
+   Jour. Oct. 27, 1900, vi, p. 790-796.
+
+REED, W. and CARROLL, J. 1901. The prevention of yellow fever. Med.
+   Record, Oct. 26, 1901, p. 441-449.
+
+REUTER, ENZIO. 1910. Acari und Geschwulstatiologie. Centralbl. Bakt.
+   Jena. Abt. 1 lvi.; Originale 339-344.
+
+REUTER, O. M. 1912. Bemerkungen uber mein neues Heteropterensystem. Ofv.
+   Finska Vetensk. Soc. Forh., liv. Afd. A. vi, p. 1-62.
+
+RIBAGA, C. 1897. Sopra un organo particolare della Cimici dei letti
+   (_Cimex lectularius_ L.). Rivista di Patologia Vegetale, v, p.
+   343-352.
+
+RICARDO, GERTRUDE. 1900. Notes on the Pangoninae. Ann. and Mag. Nat.
+   Hist. v, p. 97-121.
+
+---- 1901. Further Notes on the Pangoninae. ibid. viii, p. 286-315.
+
+---- 1904. Notes on the smaller genera of the Tabanidae. ibid. xiv, P.
+   349-373.
+
+RICKETTS, H. T. 1906-1910. Contributions to medical sciences by Howard
+   Taylor Ricketts. 1870-1910. Univ. of Chicago Press. 1911.
+
+---- 1909. A microorganism which apparently has a specific relationship
+   to Rocky Mountain spotted fever. A preliminary report. Jour. Amer.
+   Med. Assoc. iii, p. 373-380.
+
+---- Spotted fever reports 1 and 2. In the 4th Bien. Rept. State Board
+   of Health, Montana, 1909, p. 87-191.
+
+RICKETTS, H. T. and WILDER, R. M. 1910. The transmission of the typhus
+   fever of Mexico (tabardillo) by means of the louse, _Pediculus
+   vestimenti_. Journ. Am. Med. Assoc. liv. p. 1304.
+
+RILEY, C. V. and HOWARD, L. O. 1889. A contribution to the literature of
+   fatal spider-bites. Insect life, Washington, i. p. 204-211.
+
+RILEY, W. A. 1906. A case of pseudoparasitism by dipterous larvae.
+   Canadian Ent. xxxviii, p. 413.
+
+---- 1910 a. Earlier references to the relation of flies to disease.
+   Science n. s. xxxi, p. 263-4.
+
+---- 1910 b. _Dipylidium caninum_ in an American child. Science n. s.
+   xxxi, p. 349-350.
+
+---- 1911. The relation of insects to disease. Cornell Countryman ix, P.
+   51-55.
+
+---- 1912 a. Notes on the relation of insects to disease. 8vo. Ithaca,
+   N. Y. 51 p.
+
+---- 1912 b. Notes on animal parasites and parasitism. 8vo. Ithaca, N.
+   Y. 55 p.
+
+---- 1913. Some sources of laboratory material for work on the relations
+   of insects to disease. Ent. News. xxiv, p. 172-175.
+
+---- 1914. Mr. Nott's theory of insect causation of disease. Jour. of
+   Parasitology. i, p. 37-39.
+
+ROSENAU, M. J. and BRUES, C. T. 1912. Some experimental observations on
+   monkeys, concerning the transmission of poliomyelitis through the
+   agency of _Stomoxys calcitrans_. Monthly Bul. Mass. State Board of
+   Health. Vol. vii, p. 314-317.
+
+ROSS, R. 1904. Researches on Malaria. The Nobel Medical Prize Lecture
+   for 1902, Stockholm, Norstedt & Soner. 89 p. 9 pls. In "Les Prix
+   Nobel en 1902."
+
+---- 1910. The prevention of malaria. 4^o. New York. Dutton & Co. (xx +
+   669 p.).
+
+ROTHSCHILD, N. C. 1905 a. North American Ceratophyllus. Novitates
+   Zoologicae xii, p. 153-174.
+
+---- 1905 b. Some further notes on _Pulex canis_ and _P. felis_. ibid.
+   xii, p. 192-193.
+
+ROUBAUD, E. 1911. Les Choeromyies. C. R. Acad. Sci. Paris, cliii, p.
+   553.
+
+---- 1913. Recherches sur les Auchmeromyies. Bul. Sci. France et Belg.
+   Paris, p. 105-202.
+
+SACHS, HANS. 1902. Zur Kentniss der Kreuzspinnengiftes. Beitr. Chem.
+   hysiol. ii, p. 125-133. Abstr. Centralbl. Bakter. 1. Abth. xxxi.,
+   Referate, p. 788.
+
+SAMBON, L. W. 1908. Report presented at the International Conference on
+   Sleeping Sickness.
+
+---- 1910. Progress report on the investigation of pellagra. Reprinted
+   from the Journ. Trop. Med. and Hyg.; London; Bale, Sons and
+   Danielsson, 12^o. 125 p.
+
+SANDERSON, E. D. 1910. Controlling the black-fly in the White Mountains.
+   Jour. Econ. Ent. iii, p. 27-29.
+
+SAUL, E. 1910. Untersuchungen uber Beziehungen der Acari zur
+   Geschwulstatiologie. Centralbl. Bakt. Jena, Abt. 1, lv, Originale, p.
+   15-18.
+
+SAUL, E. 1913. Beziehungen des Helminthen und Acari zur
+   Geschwulstatiologie. ibid., Abt. 1, lxxi, Originale, p. 59-65.
+
+SAWYER, W. A. and HERMS, W. B. 1913. Attempts to transmit poliomyelitis
+   by means of the stable-fly (_Stomoxys calcitrans_). Journ. Amer. Med.
+   Assoc. lxi, p. 461-466.
+
+SCHAUDINN, F. 1904. Generations- und Wirtwechsel bei _Trypanosoma_ und
+   Spirochaete. Arb. aus dem kais. Gesundheitsamte xx, p. 387-493.
+
+SCHINER, J. R. 1862-64. Fauna Austriaca. Diptera, Vienna, I, lxxx + 674;
+   II, xxiii + 658.
+
+SCHNABL, J. and DZIEDZICKI, H. 1911. Die Anthomyiden 4to. Halle. p.
+   1-306.
+
+SCHWEINITZ, G. E. DE and SHUMWAY, E. A. 1904. Conjunctivitis nodosa,
+   with histological examination. Univ. of Pa. Med. Bul., Nov. 1904.
+
+SERGENT, E. and FOLY, H. 1910. Recherches sur la fievre recurrente et
+   son mode de transmission, dans une epidemie algerienne. Ann. Inst.
+   Pasteur xxiv, p. 337-373.
+
+---- 1911. Typhus recurrent Algerien. Sa transmission par les poux. Sa
+   guerison par l'arsenobenzol. C. R. Soc. Biol. Paris. lxiii, p.
+   1039-1040.
+
+SHIPLEY, E. A. 1914. Pseudo-parasitism. Parasitology, vi, p. 351-352.
+
+SILER, J. F., GARRISON, P. E., and MacNEAL, W. J. 1914. Further studies
+   of the Thompson-McFadden Pellagra Commission. A summary of the second
+   progress report. Journ. Amer. Med. Assoc. lxiii, p. 1090-1093.
+
+SKELTON, D. S. and PARKHAM, J. G. 1913. Leprosy and the bed-bug. R. A.
+   M. C. Journ., xx, p. 291.
+
+SKINNER, H. 1909. A remedy for the house-fleas. Journ. Econ. Ent. ii, p.
+   192.
+
+SMITH, G. U. 1909. On some cases of relapsing fever in Egypt and the
+   question of carriage by domestic vermin. Resume in Ann. Inst. Pasteur
+   xxiv, p. 374-375.
+
+SMITH, J. B. 1904. Report upon the mosquitoes occurring within the
+   State, their habits, life history, etc. N. J. Agric. Exp. Sta. 1904,
+   p. 1-482.
+
+---- 1908. The house mosquito, a city, town, and village problem. N. J.
+   Agric. Exp. Sta. Bul. No. 216, p. 1-21.
+
+SMITH, T. and KILBOURNE, F. L. 1893. Investigations into the nature,
+   causation, and prevention of Texas or southern cattle fever. U. S.
+   Dept. Agric., Bur. Animal Ind. Bul. 1, p. 1-301. 10 pls.
+
+SPEISER, P. 1903. Studien uber Diptera pupipara. Zeitschr. Syst.
+   Hymenopterologie und Dipt., iii, p, 145-180.
+
+SPULER, A. 1906. Ueber einen parasitisch lebenden Schmetterling,
+   _Bradypodicola hahneli_. Biol. Centralbl., xxvi, p. 690-697.
+
+STILES, C. W. 1905. A zoological investigation into the cause,
+   transmission, and source of Rocky Mountain fever. U. S. Public Health
+   and Marine Hosp. Serv. Hyg. Labr. Bul. 14, 121 p.
+
+---- 1907. Diseases caused by animal parasites. Osler's Modern Medicine,
+   i, p. 525-637.
+
+---- 1910 a. The sanitary privy: its purpose and construction. Public
+   Health Bul. No. 37. U. S. Pub. Health and Marine Hosp. Service, p.
+   1-24.
+
+---- 1910 b. The taxonomic value of the microscopic structure of the
+   stigmal plates in the tick genus _Dermacentor_. Bul. No. 62; Hyg.
+   Lab., U. S. Pub. Health and Mar. Hosp. Serc., Washington, p. 1-72. 43
+   pls.
+
+STILES, C. W. and GARDNER. 1910. Further observations on the disposal of
+   excreta. Public Health Repts. Washington. xxv, p. 1825-1830.
+
+STILES, C. W. and KEISTER, W. S. 1913. Flies as carriers of Lamblia
+   Spores. The contamination of food with human excreta. Public Health
+   Repts. Washington, xxviii, p. 2530-2534.
+
+STILES, C. W. and LUMSDEN, L. L. 1911. The sanitary privy. U. S. Dept.
+   Agric., Farmers Bul. 463, 32 p.
+
+STRICKLAND, C. 1914. The biology of _Ceratophyllus fasciatus_ Bosc., the
+   common rat-flea of Great Britain. Jour. Hygiene, xiv, p. 139-142.
+
+STRONG, R. P. and TEAGUE, O. 1912. Infectivity of the breath. Rept. of
+   Intern. Plague Conf. held at Mukden, Apr. 1911, p. 83-87.
+
+STRONG, R. P., TYZZER, E. E., and BRUES, C. T. 1913. Verruga peruviana,
+   Oroya fever and uta. Journ. Amer. Med. Assoc. lxi, p. 1713-1716.
+
+STRYKE, ANNA C. 1912. The life-cycle of the malarial parasite. Entom.
+   News. xxiii, p. 221-223.
+
+SURCOUF, J. 1913. La transmission du ver macaque par un moustique. C. R.
+   Acad. Sci., Paris, clvi, p. 1406-1408.
+
+TASCHENBERG, O. 1909. Die giftigen Tiere. 8vo. Stuttgart, Enke. (xv +
+   325 p.).
+
+TAUTE, M. 1911. Experimentelle Studien uber die Beziehungen der
+   _Glossina morsitans_ zur Schlafkrankheit. Zeitschr. f. Hyg. lxix, p.
+   553-558.
+
+TEMPLE, I. U. 1912. Acute ascending paralysis, or tick paralysis.
+   Medical Sentinel, Portland, Oregon. Sept. 1912. (Reprint unpaged.)
+
+THEOBALD, F. V. 1901+ A monograph of the Culicidae of the World. Five
+   volumes. London.
+
+THEBAULT, V. 1901. Hemorrhagie intestinale et affection typhiode causee
+   par des larves de Diptere. Arch. Parasit. iv, p. 353-361
+
+THOMPSON, D. 1913. Preliminary note on bed-bugs and leprosy. British
+   Med. Journ. 1913, p. 847.
+
+TIRABOSCHI, C. 1904. Les rats, les souris et leurs parasites cutanes
+   dans leurs rapports avec la propagation de la peste bubonique. Arch.
+   Parasit. viii, p. 161-349.
+
+TOPSENT, E. 1901. Sur un cas de myase hypodermique chez l'homme. Arch.
+   Parasit., iv. p. 607-614.
+
+TORREY, J. C. 1912. Numbers and types of bacteria carried by city flies.
+   Journ. of Inf. Dis., x, p. 166-177.
+
+TOWNSEND, C. H. T. 1908. The taxonomy of the Muscoidean flies.
+   Smithsonian Misc. Col., p. 1-138.
+
+---- 1911. Review of work by Pantel and Portchinski on reproductive and
+   early stage characters of Muscoid flies. Proc. Ent. Soc., Washington,
+   xiii, p. 151-170.
+
+---- 1912. Muscoid names. ibid., xiv, p. 45.
+
+---- 1913 a. Preliminary characterization of the vector of verruga,
+   _Phlebotomus verrucarum_ sp. nov. Insecutor Inscitiae Menstruus,
+   Washington, i, p. 107-109.
+
+---- 1913 b. The transmission of verruga by _Phlebotomus_. Journ. Amer.
+   Med. Assoc., lxi, p. 1717.
+
+---- 1914 a. The relations between lizards and _Phlebotomus verrucarum_
+   as indicating the reservoir of verruga. Science n. s., xl, p.
+   212-214.
+
+---- 1914 b. Progress of verruga work with _Phlebotomus verrucarum_ T.
+   Journ. Econ. Ent., vii. p. 357-367.
+
+TROUESSART, E. 1902. Endoparasitisme accidental chez l'homme d'une
+   espece de Sarcoptidae detriticole, (_Histiogaster spermaticus_). Arch.
+   Parasit., v, P. 449-459.
+
+TSUNODA, T. 1910. Eine Milbenart von _Glyciphagus_ als Endoparasit. D.
+   med. Wochenschr., xxxvi, p. 1327-1328.
+
+TYZZER, E. E. 1907. The pathology of the brown-tail moth dermatitis. In
+   2d Rept. of the Supt. for Suppressing the Gypsy and Brown-tail Moths,
+   Boston, 1907, p. 154-168.
+
+VAUGHAN,
+
+VERDUN, P. and BRUYANT, L. 1912. Un nouveau cas de pseudo-parasitisme
+   d'un myriapode, (_Chaetachlyne vesuviana_) chez l'homme. C. R. Soc.
+   Biol., Paris, lxiv, p. 236-237.
+
+VERJBITSKI, D. T. The part played by insects in the epidemiology of
+   plague. Transl. from Russian in Jour. Hyg., viii, p. 162-208.
+
+VILLENEUVE, J. 1914. Quelques reflexions au sujet de la tribu des
+   Calliphorinae. Bul. Soc. Ent., France, No. 8, p. 256-258.
+
+WARD, H. B. 1905. The relation of animals to disease. Science n. s.
+   xxii, P. 193-203.
+
+WATSON, J. J. 1910. Symptomology of pellagra and report of cases. Trans.
+   Nat. Conference on Pellagra, Columbia, S. C., Nov. 3 and 4, 1909, p.
+   207-218.
+
+WEED, C. M. 1904. An experiment with black-flies. U. S. Dept. Agric.,
+   Bur. Ent. Bul. n. s., 46, p. 108-109.
+
+WELLMAN, F. C. 1906. Human trypanosomiasis and spirochaetosis in
+   Portuguese Southwest Africa, with suggestions for preventing their
+   spread in the Colony. Journ. Hyg., vi, p. 237-345.
+
+WERNER, F. 1911. Scorpions and allied annulated spiders. Wellcome Trop.
+   Research Laboratories, 4th Rept., vol. B, p. 178-194. Pls. xiv-xv.
+
+WHITFIELD, A. 1912. A method of rapidly exterminating pediculi capitis.
+   Lancet 1912 (2), p. 1648. See notes.
+
+WILLISTON, S. W. 1908. Manual of the North American Diptera, New Haven,
+   p. 1-405.
+
+WILSON, G. B. and CHOWNING, W. M. 1903. Studies in _Piroplasmosis
+   hominis_. Journ. Inf. Dis., iv, p. 31-57.
+
+WILSON, W. H. 1904. On the venom of scorpions. Rec. Egyptian Gov't
+   School of Medicine, Cairo, ii, p. 7-44.
+
+
+
+
+INDEX
+
+
+Abscess, 178
+
+Acanthia, 87
+
+Acariasis, 58
+
+Acarina, 23, 58, 131, 259
+
+Acarus dysenteriae, 132
+
+Accidental parasites, 131, 132, 134
+
+Aedes, 194, 293
+
+Aedes calopus, 182, 201, 205, 206, 208
+
+Aedes cantator, 101
+
+Aedes sollicitans, 101
+
+Aedes taeniorhynchus, 101
+
+Aerobic bacteria, 152
+
+Aestivo-autumnal, 186
+
+African Relapsing Fever, 230
+
+Akis spinosa, 177
+
+Alternation of Generations, 175
+
+Amblyomma, 264
+
+Amblyomma americanum, 67
+
+Amblyomma cajennense, 67
+
+American dog tick, 228
+
+Amoeboid organism, 189
+
+Anisolabis annulipes, 177
+
+Anterior poliomyelitis, 241
+
+Anopheles, 194, 291
+
+Anopheles crucians, 199
+
+Anopheles maculipennis, 182
+
+Anopheles punctipennis, 198
+
+Anopheles quadrimaculatus, 197
+
+Anopheline, 192
+
+Anthocoris, 279
+
+Anthomyiidae, 300
+
+Anthomyia, 138
+
+Anthrax, 165
+
+Antipruritic treatment, 72
+
+Ants, 42
+
+Aphiochaeta, 295
+
+Apis mellifica, 36
+
+Arachnida, 258
+
+Araneida, 6
+
+Argas, 64
+
+Argas persicus, 63, 235, 237
+
+Argasidae, 62
+
+Argopsylla, 317
+
+Argus, 259
+
+Arilus, 284
+
+Arthropods, poisonous, 6
+
+Asopia farinalis, 177
+
+Assassin-bugs, 31, 219
+
+Auchmeromyia, 117
+
+Automeris io, 47
+
+Avicularoidea, 12
+
+
+Babesia, 226
+
+Babesia bovis, 223
+
+Babesia ovis, 225
+
+Babesiosis, 221-222
+
+Bacilli, 170
+
+Bacillus icteroides, 202, 205
+
+Bacillus pestis, 166
+
+Bacillus typhosus, 153
+
+Back swimmers, 30
+
+Bdellolarynx, 304
+
+Beauperthuy, Louis Daniel, 2
+
+Bed-bug, 86, 88, 90, 173, 219-220
+
+Bed-bug, cone-nosed, 92
+
+Blister beetles, 54
+
+Belostoma, 28, 277
+
+Belostoma americana, 31
+
+Belostomatidae, 30
+
+Bengalia, 314
+
+Bird-spiders, 10
+
+Black death, 1, 166
+
+Black flies, 33, 104, 247
+
+Black heads, 80
+
+Blaps mortisaga, 134
+
+Blepharoceridae, 286
+
+Boophilus, 264
+
+Boophilus annulatus, 67, 223-225
+
+Bot-flies, 112
+
+Blue bottle flies, 140
+
+Brill's disease, 238
+
+Brown-tailed moth, 48
+
+Bruck, 34
+
+Buthus quinquestriatus, 21
+
+
+Cabbage butterfly, 56
+
+Calliphora, 136, 140, 312
+
+Calliphora erythrocephala, 141
+
+Calobata, 296
+
+Camponotinae, 43
+
+Cancer, 254
+
+Cantharidin, 54
+
+Cantharidin poison, 55
+
+Canthariasis, 134
+
+Capsidae, 280
+
+Carriers, simple, 4, 144
+
+Carriers of disease, 144
+
+Carrion's fever, 253
+
+Caterpillar rash, 45
+
+Cat flea, 172
+
+Cattle ticks, 222
+
+Causative organism, 170
+
+Cellia, 291
+
+Centipedes, 25, 257
+
+Ceratophyllus, 120, 316
+
+Ceratophyllus acutus, 123
+
+Ceratophyllus fasciatus, 122, 172, 213
+
+Ceratopogon, 108
+
+Cheese-fly, 137
+
+Cheyletus eruditus, 271
+
+Chigger, 60, 70
+
+Chigoes, 126
+
+Chilopoda, 25, 257
+
+Chiracanthium nutrix, 18
+
+Chironomidae, 107
+
+Chorioptes, 270
+
+Chrysomelid, 55
+
+Chrysomyia, 136, 308
+
+Chrysomyia macellaria, 117, 140
+
+Chrysops, 294
+
+Chylous dropsy, 179
+
+Chyluria, 178
+
+Cicadidae, 55
+
+Cimex L., 278
+
+Cimex boueti, 92
+
+Cimex columbarius, 92
+
+Cimex hemipterus, 91, 220
+
+Cimex hirundinis, 92
+
+Cimex inodorus, 92
+
+Cimex lectularius, 87, 219
+
+Citheronia regalis, 44
+
+Clinocoris, 87
+
+Coleoptera, 134, 274
+
+Comedons, 80
+
+Complete metamorphosis, 80
+
+Compressor muscle, 20
+
+Compsomyia, 117
+
+Cone-nosed bed-bug, 92
+
+Conjunctivitis, nodular, 52
+
+Conorhinus, 282
+
+Conorhinus megistus, 93, 219-220
+
+Conorhinus rubrofasciatus, 220
+
+Conorhinus sanguisugus, 32, 92
+
+Copra itch, 72
+
+Cordylobia, 118
+
+Coriscus, 280
+
+Coriscus subcoleoptratus, 32
+
+Creeping myasis, 112
+
+Crustacea, 257
+
+Cryptocystis, 176
+
+Cryptotoxic, 54-55
+
+Cteniza sauvagei, 13
+
+Ctenocephalus, 120, 172, 213, 317
+
+Culex, 194, 201, 293
+
+Culex pipiens, 35, 98
+
+Culex quinquefasciatus, 180
+
+Culex sollicitans, 200
+
+Culex territans, 101
+
+Culicidae, 33, 97
+
+Culicin, 34
+
+Culicoides, 109, 288
+
+Cyclops, 183, 257
+
+Cynomyia, 136, 311
+
+
+Dance, St. Vitus, 8
+
+Dancing mania, 8
+
+Deer-flies, 110
+
+Definitive host, 192
+
+Demodecidae, 78
+
+Demodex, 259
+
+Demodex folliculorum, 78
+
+Dermacentor, 262
+
+Dermacentor andersoni, 67, 228
+
+Dermacentor occidentalis, 227
+
+Dermacentor variabilis, 67
+
+Dermacentor venustus, 24, 228
+
+Dermanyssidae, 68
+
+Dermanyssus, 266
+
+Dermanyssus gallinae, 68
+
+Dermatitis, 72, 77, 85
+
+Dermatobia, 115, 298
+
+Dermatobia cyaniventris, 163
+
+Dermatophilus, 317
+
+Dermatophilus penetrans, 60, 126
+
+Diamphidia simplex, 55
+
+Dimorphism, 65
+
+Direct inoculators, 4
+
+Diplopoda, 25, 257
+
+Diptera, 33, 94, 274
+
+Dipterous Larvae, 135
+
+Dipylidium, 175, 221
+
+Dipylidium caninum, 4, 175-176
+
+Dog flea, 172
+
+Dracunculus, 257
+
+Dracunculus medinensis, 182
+
+Drosophila, 296
+
+Dum-dum fever, 220
+
+Dysentery, 154
+
+
+Ear-flies, 110
+
+Earwig, 177
+
+Echidnophaga, 317
+
+Echinorhynchus, 185
+
+Elephantiasis, 178-179
+
+Empoasca mali, 33
+
+Empretia, 46
+
+English Plague Commission, 171
+
+Epeira diadema, 18
+
+Epizootic, 170
+
+Eristalis, 137, 295
+
+Essential hosts, 4, 165
+
+Eumusca, 307
+
+European Relapsing Fever, 233
+
+Euproctis chrysorrhoea, 48
+
+Eusimulium, 286
+
+
+Facultative parasites, 131
+
+Fannia, 136, 138, 145, 300
+
+Federal Health Service, 169
+
+Fever, lenticular, 237
+  African Relapsing, 230, 234
+  Carrion's, 253
+  dum-dum, 154
+  European Relapsing, 233
+  pappatici, 96
+  red water, 220
+  Rocky Mt. Spotted, 226
+  three day, 96
+  Typhus, 237
+
+Filaria, 178, 221
+  immitis, 182
+
+Filariasis, 178
+
+Flannel-moth larvae, 44
+
+Fleas, 119, 166, 213
+  cat, 172
+  dog, 172
+  human, 172, 176
+  rodent, 123, 172
+  rat, 171
+
+Flesope, 125
+
+Formaldehyde, 91
+
+Fomites, 199, 204
+
+Fulgoridae, 28
+
+Fumigation, 320
+
+
+Gamasid, 68
+
+Gangrene, 129
+
+Gastrophilus, 113, 297
+
+Giant crab spiders, 13
+
+Giant water bugs, 30
+
+Gigantorhynchus, 185
+
+Glossina, 117, 297, 303
+
+Glossina morsitans, 214, 217
+  palpalis, 215, 217, 218
+
+Glyciphagus, 267
+
+Grain moth, 69
+
+Grocer's itch, 72
+
+Guinea-worm, 182
+
+
+Habronema muscae, 156, 183
+
+Haematobia, 166, 304
+  irritans, 146
+
+Haematobosca, 304
+
+Haematomyidium, 288
+
+Haematopinus spinulosus, 213
+
+Haematopota, 294
+
+Haematosiphon, 279
+
+Haemoglobinuria, 222
+
+Haemozoin, 189
+
+Harpactor, 284
+
+Harvest mites, 60
+  effect of, 59
+
+Head-louse, 173
+
+Helminthiasis, 138
+
+Helophilus, 295
+
+Hemiptera, 27, 86, 273-275
+
+Heteropodidae, 13
+
+Heuchis sanguinea, 55
+
+Hexapod larvae, 58
+
+Hexapoda, 27, 80, 258
+
+Hippelates, 297
+
+Hippobosca, 285
+
+Histiogaster, 269
+  spermaticus, 132
+
+Homalomyia, 136, 138, 300
+
+Honey bee, 36
+  poison of, 37
+
+Hornets, 43
+
+Horn-fly, 137, 304, 308
+
+Horse-fly, 110, 165
+
+House-fly, 137-139, 144, 183
+  control of, 156, 160
+
+Human flea, 124
+
+Host, definitive, 175
+  intermediate, 175
+  primary, 175
+
+Hyalomma, 264
+  aegypticum, 224-225
+
+Hydrocyanic Acid Gas, 318
+
+Hydrotaea, 300
+
+Hymenolepis diminuta, 176
+
+Hymenoptera, 36, 275
+
+Hypoderma, 113, 298
+  diana, 113
+  lineata, 113
+
+Hypopharynx, 80
+
+
+Immunity from stings, 39
+
+Incomplete metamorphosis, 80
+
+Infantile paralysis, 162, 241
+  splenic, 220
+  Direct inoculation, 164
+
+Insects, 258
+  blood-sucking, 170
+
+Intermediate host, 192, 203
+
+Intestinal infestation, 112, 133
+  myasis, 137
+
+Isosoma, 69
+
+Itch, 73-74
+  mite, 73
+  Norwegian, 77
+
+Ixodes, 260
+  ricinus, 66, 225
+  scapularis, 66
+
+Ixodidae, 64-65
+
+Ixodoidea, 62
+
+
+Janthinosoma lutzi, 116
+
+Jigger, 60
+
+Johannseniella, 110, 288
+
+Journal of Tropical Medicine and Hygiene, 36
+
+Julus terrestris, 25
+
+June bug, 185
+
+
+Kala-azar, 220
+
+Karakurte, 14
+
+Katipo, 14
+
+King, A. F. A., 3
+
+Kircher, Athanasius, 1, 8
+
+Kissing-bug, 31
+
+
+Labium, 29, 80
+
+Labrum, 28, 80
+
+Lachnosterna, 185
+
+Laelaps, 266
+
+Lagoa crispata, 45
+
+Lamblia intestinalis, 154
+
+Langer, Josef, 37
+
+Larder beetles, 135
+
+Latrodectus, 12, 14, 17
+  mactans, 15
+
+Leishmanioses, 220
+
+Lenticular fever, 237
+
+Lepidoptera, 274
+
+Lepidopterous larvae, 134
+
+Leprosy, 252
+
+Leptidae, 112
+
+Leptis, 295
+
+Leptus, 60, 273
+
+Lice, 80
+
+Linguatulina, 258
+
+Liponyssus, 265
+
+Loemopsylla, 172, 317
+
+Lone star tick, 228
+
+Louse, body, 84
+  crab, 85
+  dog, 176
+  head, 82
+  pubic, 85
+
+Lucilia, 136, 312
+
+Lycosa tarantula, 10
+
+Lycosidae, 10
+
+Lyctocoris, 279
+
+Lygus pratensis, 33
+
+Lymphangitis, 67
+
+Lymph scrotum, 178
+
+Lyperosia, 304
+
+Lyperosiops, 305
+
+
+Macloskie, 34
+
+Maggots, rat-tail, 137
+
+Magnes sive de Arte Magnetica, 8
+
+Malaria, 186
+
+Malmigniatte, 14
+
+Mandibles, 28, 80
+
+Mange, 73-75
+
+Margaropus, 237, 264
+  annulatus, 223
+
+Masked bed-bug hunter, 32
+
+Mastigoproctus giganteus, 19, 80
+
+Maxillae, 28
+
+Meal infesting species, 135
+
+Melanin granules, 189
+
+Melanolestes, 280
+  picipes, 32
+
+Mena-vodi, 14
+
+Mercurialis, 1
+
+Merozoites, 190
+
+Metamorphosis, 80
+
+Miana bug, 63
+
+Microgametoblast, 192
+
+Midges, 107
+
+Migratory ookinete, 192
+
+Millipedes, 25, 257
+
+Mites, 23, 58
+
+Monieziella, 269
+
+Mosquitoes, 33, 97, 178, 196, 250
+  treatment for bites of, 34, 36, 102
+
+Musca, 137, 307
+  domestica, 139, 145, 146, 157, 162
+
+Muscidae, 117
+
+Muscina, 137, 146, 307
+  stabulans, 140
+
+Mutualism, 57
+
+Myasis, 112, 135
+  intestinal, 135-140
+  nasal, 141
+
+Mycterotypus, 287
+
+Myiospila, 146, 307
+
+Myriapoda, 225, 132, 257
+
+
+Nagana, 165, 214
+
+Nasal infestation, 114, 133
+
+Necrobia, 135
+
+Nematode parasite, 182
+
+Nepa, 28
+
+Nephrophages sanguinarius, 132
+
+Nettling insects, 43
+  larvae, poison of, 53
+
+Neurasthenia, 89
+
+Nits, 86
+
+North African Relapsing Fever, 234
+
+Norwegian itch, 77
+
+No-see-ums, 109
+
+Notoedres, 269
+  cati, 78
+
+Notonecta, 28, 277
+
+Notonectidae, 30
+
+Nott, Dr. Josiah, 2
+
+Nuttall, 34
+
+
+Occipital headaches, 138
+
+Oecacta, 288
+
+Oeciacus, 279
+
+Oesophageal diverticula, 35
+
+Oestridae, 112, 136
+
+Oestris ovis, 113
+
+Oestrus, 298
+  oocyst, 192
+  ookinete, 192
+
+Opsicoetes personatus, 32
+
+Opthalmia, 155
+  nodosa, 52
+
+Oriental sore, 221
+
+Ornithodoros, 65, 260
+  moubata, 220, 230
+
+Orthotylus flavosparsus, 33
+
+Ornithomyia, 286
+
+Oroya, 253
+
+Oscinus, 297
+
+Otiobius, 259
+  megnini, 65
+
+Otodectes, 271
+
+
+Pangonia, 294
+
+Pappatici fever, 96
+
+Parasimulium, 286
+
+Parasite, 3, 57, 131, 134, 182
+  accidental, 3, 131, 134
+  facultative, 3, 57, 131
+  nematode, 182
+  stationary, 57
+  temporary, 57
+  true, 3
+
+Parasitism, accidental, 134
+
+Pathogenic bacteria, 152
+  organisms, 144, 164
+
+Pawlowsky, 81
+
+Pediculoides, 267
+  ventricosus, 69, 72
+
+Pediculosis, 81
+
+Pediculus, 275
+  corporis, 84, 233, 238
+  humanus, 82, 173
+
+Pellagra, 162, 246
+
+Pernicious fever, 186
+
+Pest, 166
+
+Phidippus audax, 19
+
+Philaematomyia, 306
+
+Phisalix, 13, 43
+
+Phlebotomus, 289
+  papatasii, 94
+  verrucarum, 254
+  vexator, 95
+
+Phora, 295
+
+Phormia, 136
+
+Phormictopus carcerides, 13
+
+Phthirus pubis, 85, 275
+
+Phortica, 296
+
+Pieris brassicae, 56
+
+Piophila, 297
+
+Piophila casei, 136, 137
+
+Piroplasmosis, 222
+
+Plague, 166
+  bubonic, 166, 169, 170
+  pneumonic, 167
+
+Plasmodium, 186
+
+Platymetopius acutus, 33
+
+Plica palonica, 83
+
+Pneumonic, 166
+  plague, 167, 173
+
+Poisoning by nettling larvae, 53
+
+Poison of spiders, 7
+
+Pollenia, 308
+  rudis, 146, 147
+
+Primary gland, 28
+
+Prionurus citrinus, 20
+
+Prosimulium, 286
+
+Protocalliphora, 136, 312
+
+Protozoan blood parasite, 165
+
+Pseudo-tubercular, 52
+
+Psorophora, 293
+
+Psoroptes, 270
+
+Psychodidae, 94
+
+Pulex, 120, 124, 126, 172, 317
+  cheopis, 172
+  irritans, 124
+  penetrans, 126
+  serraticeps, 120
+
+Pulvillus, 150
+
+Punkies, 109
+
+Pycnosoma, 308
+
+
+Rasahus, 280
+  thoracicus, 32
+
+Rat fleas, 120, 124, 171
+
+Rat louse, 213
+
+Red bugs, 70-72
+
+Reduviidae, 31
+
+Reduviolus, 280
+
+Reduvius, 282
+  personatus, 32
+
+Redwater fever, 222
+
+Relapsing fever, 230, 233
+
+Rhinoestrus nasalis, 115
+
+Rhipicentor, 264
+
+Rhipicephalus, 264
+
+Rhizoglyphus, 269
+
+Rhodnius, 281
+
+Rocky Mountain Spotted Fever, 226
+  spotted fever tick, 67
+
+Russian gad-fly, 115
+
+
+St. Vitus's or St. John's dance, 8
+
+Salivary syringe, 28
+
+Sand-flies, 109, 250
+
+Sanguinetti, 11
+
+Sarcophaga, 136, 142, 143
+
+Sarcophila, 302
+
+Sarcopsylla, 317
+  penetrans, 126
+
+Sarcoptes, 270
+  minor, 78
+  scabiei, 73
+
+Sarcoptidae, 72
+
+Scabies, 72, 73, 74, 75
+
+Scaurus striatus, 177
+
+Schaudinn, 34
+
+Schizont, 189, 190
+
+Scholeciasis, 134
+
+Scolopendra morsitans, 26
+
+Scorpions, 20
+  poison of, 21
+
+Screw worm fly, 140
+
+Sepsidae, 296
+
+Sepsis, 136, 297
+
+Shipley, 34
+
+Sibine, 46
+
+Silvius, 294
+
+Simple carriers, 4, 144
+
+Simuliidae, 33, 104
+
+Simulium, 247, 249, 286, 321
+  pictipes, 104
+
+Siphonaptera, 119, 274, 316
+
+Siphunculata, 80, 275
+
+Sitotroga cerealella, 69
+
+Skippers, 137
+
+Sleeping sickness, 166, 215
+
+Snipe-flies, 112
+
+Solpugida, 22
+
+Spanish fly, 54
+
+Spermatozoa, 192
+
+Spinose ear-tick, 65
+
+Spirochaeta, 35
+  berberi, 234
+  duttoni, 234
+
+Spirochaetosis, 235
+
+Sporozoite, 189
+
+Spotted fever, 67, 226
+
+Squirrel flea, 123
+
+Stable-fly, 137, 160, 163, 165
+
+Stegomyia, 182, 293
+  calopus, 206
+  fasciata, 206
+
+Stomoxys, 137, 305
+  calcitrans, 117, 146, 160, 161, 165, 242
+
+Straw-worm, 69
+
+Stygeromyia, 305
+
+Sucking stomach, 35
+
+Sulphur ointment, 77
+
+Surra, 165
+
+Symbiosis, 57
+
+Symphoromyia, 112, 295
+
+
+Tabanidae, 110
+
+Tabanus, 110, 166, 294
+  striatus, 165
+
+Taenia, 175
+
+Tapeworm, 4, 176
+
+Tarantella, 8
+
+Tarantism, 8
+
+Tarantula, 10
+
+Tarsonemidae, 69
+
+Tarsonemus, 267
+
+Tenebrionid beetles, 127
+
+Tersesthes, 110, 288
+
+Tetanus, 129
+
+Tetranychus, 273
+
+Texas fever, 220-223
+
+Three-day fever, 96
+
+Tick, 23, 226
+  bites, Treatment of, 68
+  fever, 230
+  paralysis, 67
+
+Treatment,
+  Bee stings, 36, 41
+  Bites of,
+    Bed-bugs, 90, 93
+    Blackflies, 107
+    Buffalo flies, 107
+    Bugs, 31, 33
+    Centipedes, 26, 27
+    Chiggers, 127
+    Chigoes, 127
+    Fleas, 127
+    Harvest mites, 61
+    Jiggers, 129
+    Lice, 83, 85
+    Mosquitoes, 34, 36, 102
+    Phlebotomus flies, 97
+    Sand flies, 96, 107, 109
+    Scorpions, 22, 23
+    Spiders, 19
+    Ticks, 61, 68, 72
+    Ticks, ear, 65
+  Blister beetle poison, 55
+  Brown-tail moth rash, 45
+  Cantharidin poison, 55
+  Caterpillar rash, 45
+  Ear ticks, 65
+  House fly control, 156, 160
+  Itch, 77
+  Itch, grocer's, 72
+  Lice, 85
+  Nasal myasis, 143
+  Rocky Mt. spotted fever, 228, 229
+  Rash, caterpillar, 45
+  Scabies, 77
+  Sleeping sickness control, 218
+  Spotted fever, 228, 229
+  Stings, bee, 36, 41
+  Typhus fever, prophylaxis, 239
+
+Trichodectes canis, 176
+
+Trichoma, 82
+
+Trineura, 295
+
+Trochosa singoriensis, 11
+
+Trombidium, 60, 273
+
+True insects, 80
+
+Trypanosoma, 35
+
+Trypanosoma, brucei, 165
+
+Trypanosoma cruzi, 219
+
+Trypanosoma lewisi, 213
+
+Trypanosomiases, 212
+
+Trypanosomiasis, 165, 219
+
+Tsetse flies, 117, 166, 214, 219
+
+Tsetse flies disease, 165
+
+Tuberculosis, 155
+
+Tumbu-fly, 118
+
+Tydeus, 271
+
+Typhoid, 155
+
+Typhoid fever, 154
+
+Typhus, 237
+
+Typhus fever, 237
+
+Tyroglyphus, 72, 131, 268
+
+Dr. Tyzzer, 49
+
+
+Uranotaenia, 292
+
+
+Vancoho, 14
+
+Varicose groin glands, 178
+
+Verruga peruviana, 253
+
+Vescicating insects, 54
+
+
+Wanzenspritze, 29
+
+Warble-flies, 112
+
+Wasps, 43
+
+Whip-scorpions, 19
+
+Wohlfahrtia, 143, 302
+
+Wolf-spiders, 10
+
+Wyeomyia smithii, 101, 293
+
+
+Xenopsylla, 172, 317
+
+Xenopsylla cheopis, 171, 124
+
+Xestopsylla, 317
+
+
+Yaws, 2
+
+Yellow fever, 196, 203, 205
+
+
+
+
+TRANSCRIBER'S NOTES
+
+The following discrepancies in the text are as in the original:
+
+  The inconsistent hyphenation of the following:
+    assassin-bugs/assassin bugs;
+    bedbug/bed-bug (and bedbugs);
+    beekeeper/bee-keeper (and beekeepers);
+    blackflies/black-flies;
+    blow-flies/blow flies;
+    bluebottles/blue-bottles;
+    bot-flies/bot flies;
+    bristlelike/bristle-like;
+    browntail/brown-tail;
+    coextensive/co-extensive;
+    deer-flies/deer flies;
+    dorsocentral/dorso-central;
+    ectoparasites/ecto-parasites;
+    endoparasites/endo-parasites;
+    flesh-fly/flesh fly (and flesh flies);
+    hotbed/hot-bed;
+    housefly/house-fly (and houseflies);
+    horsefly/horse-fly (and horse flies);
+    horse-manure/horse manure;
+    midsummer/mid-summer;
+    preeminently/pre-eminently;
+    sandfly/sand-fly (and sandflies);
+    screw-worm fly/screw worm fly;
+    stable-fly/stable fly;
+    subequal/sub-equal;
+    subfamily/sub-family;
+    subtropical/sub-tropical;
+    tapeworm/tape-worm (and tapeworms);
+    today/to-day;
+    tsetse-flies/tsetse flies;
+    widespread/wide-spread;
+    wormlike/worm-like.
+
+  Inconsistent spelling of the following:
+    defence/defense;
+    disc/disk;
+    hemolysis/haemolysis;
+    hemolytic/haemolytic;
+    hexapod/hexopod;
+    Levaditi/Lavaditi;
+    metalescent/metallescent;
+    Mitzmain/Mitzman;
+    Neveau-Lemaire/Neveau-Lamaire;
+    offence/offense;
+    Phthirus/Phthirius
+    Portschinsky/Portchinsky/Portchinski;
+    travelled/traveled;
+    ventra-/ventro-;
+    Villot/Villet;
+    Wohlfartia/Wohlfahrtia;
+
+toxine, insiduous, efficaceous, cyanid are spelt as in the original
+
+In the first paragraph of chapter XII, "the student might not be lead"
+is as in the original. Lead perhaps should be led
+
+In the bibliography, the entry for Vaughan without a text specified is
+as in the original
+
+
+
+
+
+End of the Project Gutenberg EBook of Handbook of Medical Entomology, by 
+William Albert Riley and Oskar Augustus Johanssen
+
+*** END OF THIS PROJECT GUTENBERG EBOOK HANDBOOK OF MEDICAL ENTOMOLOGY ***
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