- Diagram of a longitudinal section of a mosquito
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. - Normal position of the larvæ of Culex and Anopheles in the water
(a) Normal position of the larvæ of Culex and Anopheles in the water. Culex, left; Anopheles, middle; Culex pupa, right hand figure - A flesh fly
A flesh fly - A medieval method of combating the plague. The persecution of the anointers in Milan in 1630
In Milan the visitation of 1630 was credited to the so-called anointers,—men who were supposed to spread the plague by anointing the walls with magic ointment—and the most horrible tortures that human ingenuity could devise were imposed on scores of victims, regardless of `rank` or of public service. Manzoni's great historical novel, "The Betrothed" has well pictured conditions in Italy during this period. - A millipede
The Diplopoda, or millipedes, 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. - A solpugid (Eremobates cinerea)
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. - A true scorpion
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 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 - A whip-scorpion
The tailed whip-scorpions, belonging to the family Thelyphonidæ, are represented in the United States by the giant whip-scorpion Mastigoproctus giganteus, 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. - Aëdes calopus; larva
The yellow fever mosquito breeds in cisterns, water barrels, pitchers and in the various water receptacles about the house. In our own Southern States it very commonly breeds in the above-ground cisterns which are in general use. Often the larvæ are found in flower vases, or even in the little cups of water which are placed under the legs of tables to prevent their being overrun by ants. They have been repeatedly found breeding in the holy water font in churches. In short, they breed in any collection of water in close proximity to the dwellings or gathering places of man. - An American tarantula
n 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.). On the other hand, in this country, though there are many Lycosidæ, the term "tarantula" has been applied to members of the superfamily Avicularoidea, including the bird-spiders. - Mosquito
Anopheles crucians. Female - Mosquito
Anopheles punctipennis. Female - Anopheles quadrimaculatus mosquito
Anopheles quadrimaculatus mosquito, male and female - Argus persicus. Capitulum of male
Until recently, the ticks attracted comparatively little attention from entomologists. Since their importance as carriers of disease has been established, interest in the group has been enormously stimulated and now they `rank` second only to the mosquitoes in the amount of detailed study that has been devoted to them. The ticks are the largest of the Acarina. They are characterized by the fact that the hypostome, or "tongue" is large and file-like, roughened by sharp teeth. - Auchmeromyia luteola
Auchmeromyia luteola, the Congo floor maggot. This is a muscid of grewsome habits, which has a wide distribution throughout Africa. The fly deposits its eggs on the ground of the huts of the natives. - Beak of hemipteron
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. 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 serrated, depending on the species concerned. - Cross section of the larva of the browntail moth showing the tubercles bearing the poison hairs
- Culex sollicitans. Female
- Culicoides guttipennis - (a) adult, (×15) (b) head of same (c) larva (d) head (e) pupa
- Dancing Mania
- Demodex folliculorum
- Calliphora erythrocephala
- Chrysomyia macellaria
- Conorhinus abdominalis
- Conorhinus sanguisugus
- Cordylobia anthropophaga
- Echidnophaga gallinacea
- Eggs of Anopheles
- Epithelium underlying poison hairs of the larva of the browntail moth (larger scale)
- Epithelium underlying poison hairs of the larva of the browntail moth
- Harvest mites. (Larvæ of Trombidium)
- Dermanyssus gallinæ, female
- Dipylidium caninum. Rostrum evaginated and invaginated
- Dipylidium caninum. The double pored tapeworm of the dog
- Dog flea
- Some early medical entomology
- Sting of a honey bee
- The cattle tick (Boophilus annulatus). (a) Female; (b) male
- The Italian tarantula
- The yellow fever mosquito (Aëdes calopus)
- Two common centipedes
- Xenopsylla cheopis, male
- Head and pronotum of (a) dog flea; (b) of cat flea; (c) of hen flea (d) Nycteridiphilus (Ischnopsyllus) hexactenus
- Head of a spider showing poison gland (c) and its relation to the chelicera (a)
- Ixodes ricinus; male, ventral aspect
- Larva of Anopheles
- Larva of Fannia scalaris
- Larva of Simulium
- Left hand stigmata of the larvæ of muscoidea
- Left spiracle of nymph of Argas persicus
- Life cycle of the malarial parasite
- Linguatula. (a) larva; (enlarged). (b) adult; (natural size)
- Lucilia cæsar
- Mandible of Scolopendra cingulata showing venom gland
- Muscina stabulan
- Notœdres cati, male and female
- Otiobius (Ornithodoros) megnini, head of nymph
- Otiobius (Ornithodoros) megnini, male. (a) dorsal, (b) ventral aspect
- Pediculoides ventricosus, female
- Pediculus showing the blind sac (b) containing the mouth parts (a) beneath the alimentary canal (p)