THE Louse is an insect of the order of the aptera, that is to say, those that have no wings. Several animals are pestered by that or similar kind of vermin, and every one is different according to the substance upon which it feeds. The human Louse deserves a particular notice. Its skin is very transparent so that when examined by a powerful microscope you can see its blood and intestines in motion. The body is divided into three parts; the head, the corselet, and the belly. In the head are situated two black eyes, and over each a horn or antenna, composed of five joints, and surrounded with hairs; and instead of a mouth, this teazing insect is armed with an instrument inclosing a piercer and a sucker, which it thrusts into the skin and through which it draws the blood and humours that constitute its principal support; this piercer is supposed to be seven hundred times smaller than a common hair! and is capable of being retracted or protracted. The breast is also transparent, and in it are situated the six legs, consisting of five joints each, and covered with a skin resembling shagreen. At the extremity of each foot are two claws of unequal size, covered with hairs; the skin of the belly is also like shagreen, and at the extremity are small prominencies as may be observed in several other insects. By the help of the microscope the whole process of its sucking the blood and humours is plainly seen, as well as the passing of them through the guts. They lay about an hundred eggs in twelve days; and when the body upon which they feed is labouring under some disease, the fecundity of this insect is most astonishing. These eggs are naturally hatched in six days, so that in the space of two months a female might have five thousand offsprings. This peculiar disease was more frequent amongst the ancients than it is with us, which was owing to their using hardly any linen cloth next to their skin. Their woollen toga, mantles, and other coverings, which were but now and then sent to the scourer, harboured the vermin much more snug than our linen garments. Phercydes, a philosopher of Scyros, who had the honour of being the master of Pythagoras, declared, in a letter which he wrote a few days before his death, “that he was covered with lice,” and did not seem to show any reluctance at mentioning it. The best preventative against this pest is cleanliness.
What ought to astonish us is, that a child born in a clean and respectable house, distant from any place where this vermin may abide, will, however, be plagued with it, till attention and maternal care have destroyed the whole. Do the eggs fly in the air? are they so small as to be wafted from countries to countries, and thrive when they alight on a fruitful ground? It is a consideration left to naturalists, and which might involve us in too long a discussion to find place here.
The Mite is a well known insect, which preys upon fresh and putrid substances, particularly where a sort of fermentation is excited by heat. It is a crustaceous animal, and like the common louse, almost transparent. It has a sharp snout, two small eyes, and six legs. It is curious to see how their busy tribes work, in common, to hew down huge rocks and mountains of old cheese, in order to get at that particular spot where they can more comfortably feed themselves and deposit their eggs, which are so minute that, as it has been computed, a pigeon’s egg exceeds the dimension of one of them thirty millions of times. That life, instinct, and perpetuity of reproduction should exist in so small a being, is most astonishing, and yet the Mite is not the smallest of living creatures. The microscope has opened the eye of man upon a world of innumerable animalcules, which people the three inhabitable elements of Nature. Myriads of them dance with the motes in the sun-beams, they swim by millions in a dew-drop, brew and prepare the glebe for vegetation, and ebb and flow with the air of our breath.
“ – These conceal’d
By the kind art of forming Heaven, escape
The grosser eye of man; for if the worlds,
In worlds enclos’d, should on his senses burst,
From cates ambrosial and the nectar’d bowl
He would, abhorrent, turn; and in dead night,
When silence sleeps o’er all be stunn’d with noise.”
IS another of those vexing and plaguing little creatures which mankind has been doomed to be tormented with. Less ignoble than the louse and of a lightlier nature, it is [nevertheless] very obnoxious, as, by its leapings, it often escapes the catch of the fingers. It is oviparous, and the egg, which is hardly discernible with the naked eye, yields a small white worm, all beset with hairs; those eggs as well as those of the louse, are generally called nits. The Flea is an active, troublesome, bloodthirsty insect; it has a small head, large eyes, and roundish but compressed body, which is covered with a kind of armour resembling the tortoise-shell in colour and transparency; the plates of which this skin is composed, are also armed with spines or bristles; it has six legs, two of which are much longer than the other, in order to enable the insect to make such wonderous leaps, as to raise the body above two hundred times its diameter. It is observed that in one day the Flea will eat above ten times its own bulk. They suck the blood out of the small arteries and veins next to the skin, which they perforate with an instrument naturally contrived for this purpose, leave a red mark behind, and discharge the blood which they have digested in red spots upon our linnen. Cleanliness is also the best preventative against fleas.