TRANSCRIBERS' NOTES
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.
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
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 [Heilkunft] 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 R5.
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 R4+5 read M1+2.
309 legend under [fig. 168] add Bureau of Entomology.
312 [line 36], for "near apex" read "of M1+2".
313 running head, for Muscidæ read Muscoidea.
314 [line 29], for "distal section" read "distally M1+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.
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.
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.
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.
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.
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.
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."
"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]).
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.
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 tarsi 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.
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.
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.
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.
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
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.
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.
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]).
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. 19b]) 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. 19f]) 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.
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.
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.
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."
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. 19g]), Rasahus thoracicus, Rasahus biguttatus ([fig. 22]), Conorhinus sanguisugus ([fig. 71]), and C. abdominalis ([fig. 23]).
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.
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.
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.
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.
