Many insects, however, are engendered in a different manner; and some more especially from dew. This dew settles upon the radish[143] leaf in the early days of spring; but when it has been thickened by the action of the sun, it becomes reduced to the size of a grain of millet. From this a small grub afterwards arises, which, at the end of three days, becomes transformed into a caterpillar. For several successive days it still increases in size, but remains motionless, and covered with a hard husk. It moves only when touched, and is covered with a web like that of the spider. In this state it is called a chrysalis, but after the husk is broken, it flies forth in the shape of a butterfly. CHAP. 38. (33.)—ANIMALS WHICH BREED IN WOOD. In the same manner, also, some animals are generated in the earth from rain, and some, again, in wood. And not only wood-worms[144] are produced in wood, but gad-flies also and other insects issue from it, whenever there is an excess of moisture; just as in man, tape-worms[145] are sometimes found, as much as three hundred feet or more in length. CHAP. 39.—INSECTS THAT ARE PARASITES OF MAN. WHICH IS THE SMALLEST OF ANIMALS? ANIMALS FOUND IN WAX EVEN. Then, too, in dead carrion there are certain animals produced, and in the hair, too, of living men. It was through such vermin as this that the Dictator Sylla,[146] and Alcman, one of the most famous of the Grecian poets, met their deaths. These insects infest birds too, and are apt to kill the pheasant, unless it takes care to bathe itself in the dust. Of the animals that are covered with hair, it is supposed that the ass and the sheep are the only ones that are exempt from these vermin. They are produced, also, in certain kinds of cloth, and more particularly those made of the wool of sheep which have been killed by the wolf. I find it stated, also, by authors, that some kinds of water[147] which we use for bathing are more productive of these parasites than others. Even wax is found to produce mites, which are supposed to be the very smallest of all living creatures. Other insects, again, are engendered from filth, acted upon by the rays of the sun—these fleas are called “petauristæ,”[148] from the activity which they display in their hind legs. Others, again, are produced with wings, from the moist dust that is found lying in holes and corners. CHAP. 40. (34.)—AN ANIMAL WHICH HAS NO PASSAGE FOR THE EVACUATIONS.