Natural History, a little insect famous for a ticking noise, like the beat of a watch, which the vulgar have long taken for a prelude of death in the family where it is heard: whence it is also called pediculus fatidicus, mortifaga, pulsatarius, &c.

There are two kinds of death-watches. Of the first we have a good account in the Phil. Transf. by Mr Allen. It is a small beetle, 5-16ths of an inch long, of a dark brown colour, spotted; having pellucid wings under under the vagina, a large cap or helmet on the head, and two antennae proceeding from beneath the eyes, and doing the office of proboscides. The part it beats withal, he observed, was the extreme edge of the face, which he chooses to call the upper-lip, the mouth being protracted by this bony part, and lying underneath out of view.

This account is confirmed by Dr Derham; with this difference, that instead of ticking with the upper lip, he observed the insect to draw back its mouth, and beat with its forehead. That author had two death-watches, a male and a female, which he kept alive in a box several months; and could bring one of them to beat whenever he pleased, by imitating its beating. By this ticking noise he could frequently invite the male to get up upon the other in the way of coition. When the male found he got up in vain, he would get off again, beat very eagerly, and then up again: Whence the ingenious author concludes those pulsations to be the way whereby these insects woo one another, and find out and invite each other to copulation.

The second kind of death-watch is an insect in appearance quite different from the first. The former only beats seven or eight strokes at a time, and quicker; the latter will beat some hours together without intermission; and his strokes are more leisurely, and like the beat of a watch. This latter is a small grayish insect, much like a louse when viewed with the naked eye.

It is very common in all parts of the house in the summer-months: it is very nimble in running to shelter, and fly of beating when disturbed; but will beat very freely before you, and also answer the beating, if you can view it without giving it disturbance, or shaking the place where it lies, &c. The author cannot say whether they beat in any other thing, but he never heard their noise except in or near paper. As to their noise, the same person is in doubt whether it be made by their heads, or rather snouts, against the paper; or whether it be not made after some such manner as grasshoppers and crickets make their noise. He inclines to the former opinion. The reason of his doubt is, that he observed the animal's body to shake and give a jerk at every beat, but could scarce perceive any part of its body to touch the paper. But its body is so small and near the paper, and its motion in ticking so quick, that he thinks it might be, yet he not perceive it. The ticking, as in the other, he judges to be a wooing act; as having observed another, after much beating, come and make offers to the beating insect, who, after some offers, left off beating, and got upon the back of the other. When they were joined, he left off again; and they continued some hours joined tail to tail, like dog and bitch in coition. Whether this insect changes its shape, and becomes another animal or not, he cannot say; though he has some cause to suspect that it becomes a sort of fly. It is at first a minute white egg, much smaller than the nits of lice; though the insect is near as big as a louse. In March it is hatched, and creeps about with its shell on. When it first leaves its shell, it is even smaller than its egg; though that be scarce discernible without a microscope. In this state it is perfectly like the mites in cheese. From the mite-state they grow gradually to their mature perfect state. When they become like the old ones, they are at first very small, but run about much more swiftly than before.