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Chap. XXVIII

CURIOSITIES RESPECTING INSECTS-(Continued.) The Flea-On the Duration of the Life of a Flea-The Louse. THE FLEA, has two eyes and six feet, fitted for leaping; the feelers are like threads; the rostrum is inflected, setaceous, and armed with a sting; and the belly is compressed. Fleas bring forth eggs, which they deposit on animals that afford them a proper food. Of these eggs are hatched white worms of a shining pearl colour, which feed on the scurfy substance of the cuticle, the downy matter gathered in the piles or folds of clothes, or other similar substances. In a fortnight they come to a tolerable size, and are very lively and active; and, if at any time disturbed, they suddenly roll themselves into a kind of ball. Soon after this, they come to creep, after the manner of silk-worms, with a very swift motion. When arrived at their size, they hide themselves as much as possible, and spin a silken thread out of their mouth, wherewith they form themselves a small round bag, or case, white within as paper, but without always dirty, and fouled with dust. Here, after a fortnight's rest, the animalcule bursts out, transformed into a perfect flea, leaving its exuviæ in the bag While it remains in the bag, it is milk-white till the second day before its eruption, when it becomes coloured, grows hard, and gets strength; so that, upon its first delivery, it springs nimbly away. The flea is covered all over with black, hard, and shelly scales or plates, which are curiously jointed, and folded over each other in such a manner as to comply with all the nimble motions of the creature. These scales are finely polished, and beset about the edges with short spikes, in a very beautiful and regular order. Its neck is finely arched, and resembles the tail of a lobster: the head is also very extraordinary; for from the snout-part of it proceed the two fore-legs, and between these is placed the piercer, or sucker, with which it penetrates the skin to get its food. Its eyes are very large and beautiful, and it has two short horns, or feelers. It has four other legs, joined all at the breast. These, when it leaps, fold short, one within another; and then, exerting their spring all at the same instant, they carry the creature to a surprising distance. The legs have several joints, are very hairy, and terminate in two long and hooked sharp claws. The piercer, or sucker, of the flea, is lodged between its fore-legs, and includes a couple of darts or lancets, which, after the piercer has made an entrance, are thrust farther into the flesh, to make the blood flow from the adjacent parts, and occasion that round red spot, with a hole in the centre of it, vulgarly called a fleabite. This piercer, its sheath opening sidewise, and the two lancets within it, are very difficult to be seen, unless the two forelegs, between which they are hid, be cut off close to the head; for the flea rarely puts out its piercer, except at the time of feeding, but keeps it folded inwards; and the best way of seeing it, is by cutting off first the head, and then the fore-legs, and then it is usually seen thrust out in convulsions. By keeping fleas in a glass tube corked up at both ends, but so as to admit fresh air, their several actions may be observed. They may be thus seen to lay their eggs, &c. They do not lay their eggs all at once, but by ten or twelve in a day, for several days successively, which eggs will be afterwards found to hatch successively, in the same order. The flea may easily be dissected in a drop of water; and thus the stomach and bowels, with their peristaltic motion, may be discovered very plainly, with the veins and arteries, though minute beyond all conception. This bloodthirsty insect, which fattens at the expense of the human species, prefers the more delicate skin of women, but preys neither upon epileptic persons, nor upon the dead or dying. It loves to nestle in the fur of dogs, cats, and rats. The nests of river-swallows are sometimes plentifully stored with them. Fleas are apterous, walk but little, but leap to a height equal to two hundred times that