OF THE CIMEX LECTULARIUS, OR BED BUG.
Various are the antipathies of mankind, but all appear to unite in their dislike to this animal and the louse, and to detest them as their natural and nauseous enemies. The bug “intrudes upon the peace of mankind, and often banishes that sleep which even anxiety and sorrow permitted to approach: the night is the season when the bed bug issues from its retreat to make its depredations; by day it lurks in the most secret parts of the bed, takes the advantage of every chink and cranny to make a secure lodgement, and contrives its habitation with so much art, that scarce any industry can discover its retreat; but when darkness promises security, it then issues from every corner of the bed, drops from the tester, and crawls from behind the arras, and travels to the unhappy patient, who vainly wishes for rest and refreshment.”
Linnæus is of opinion that this insect is not originally of European growth, but was imported from some other country. It is not only disagreeable on account of the extremely offensive smell proceeding from it, but also because of the rapidity with which it increases, and the voraciousness of its appetite. It has two brown small prominent eyes, two antennæ, and a crooked proboscis, which lies close under the breast. Instead of wings, we find on the first ring of the belly two flat pieces which entirely cover it, and extend towards the sides. These plates, the trunk, and the head, are amply set with hairs. The proboscis is divided transversely into four parts, which are probably so many articulations; this piece is best seen on the under side of the bug, being bent flat on the belly, and reaching half way down the body; but the mechanism of this, as well as other parts of these minute insects, cannot be perfectly understood, but by an accurate examination with the microscope. It has six legs, each of which has three joints; these legs, like those of the fly, are formed for running, not leaping; the skin is shagreened, and the separation of the rings usually marked by a smooth shining band. On the belly, at a small distance from the edge, a set of circular spots may be perceived, two on each ring, except the last; these are the spiracula. Examined internally, we find one large artery, a stomach, and intestines. The instant it perceives the light, it endeavours to gain its obscure habitation, and seldom fails in making good its retreat.
OF THE PEDICULUS HUMANUS, OR LOUSE.
“Whenever wretchedness, disease, and hunger seize upon man, the louse seldom fails to add itself to the tribe, and to increase in proportion to the number of his calamities.”
When the human louse is examined with the microscope, its deformity fills us with disgust. In the head we may distinguish two fine black eyes, looking backward and fenced with hair; near these are the two antennæ, each of which has five joints set with short bristles; the fore-part of the head is rather long, the hinder more round or obtuse; there is a small part that projects from the nose or snout, this serves as a sheath or case to the proboscis or piercer, which the creature thrusts into the skin to draw out the blood and humours which are its destined food, for it has no mouth which opens in the common way.
This proboscis has been estimated to be seven-hundred times smaller than a hair; it is contained in another case within the first, and can be drawn in or thrust out at pleasure; the skin is hard and transparent. From the under side proceed six legs, each of which has five joints, and terminates in two unequal hooked claws, these it uses as we would a thumb and finger; there are hairs between the claws, as well as all over the legs; the body finishes in a cloven tail, which is generally covered, and partly concealed by hairs.
From the extreme transparency of its skin, the internal parts may be seen to greater advantage than in any other insect; as, the various ramifications of the veins and arteries, in which a kind of regular pulsation may be observed, as well as the peristaltic motion of the intestines, which is continued from the stomach to the tail. When the louse feeds, the blood rushes like a torrent into the stomach, moving with so strong a propulsion and contraction, as appears very curious. The digestive powers are so great, that the colour of the blood changes in its passage from thick and black at its first entrance, to a fine ruby colour in the intestines, and nearly white in the veins. Its greediness is so great, that the excrement contained in the intestines is ejected at the same time, to make room for this new supply. There is scarce any animal that multiplies so fast as this unwelcome intruder; the moment it is excluded from the egg it begins to breed.
It would be endless to describe the various creatures which go under the name of lice, and swarm upon every part of nature. The reader, desirous of a more particular account of those which infest various animals, will obtain full satisfaction, by consulting Rhedi’s Treatise de Generatione Insectorum.