CHAP. 41. (35.)—MOTHS, CANTHARIDES, GNATS—AN INSECT THAT BREEDS IN THE SNOW.
Dust, too, is productive of worms152 in wools and cloths, and this more especially if a spider should happen to be enclosed in them: for, being sensible of thirst, it sucks up all the moisture, and thereby increases the dryness of the material. These will breed in paper also. There is one kind which carries with it its husk, in the same manner as the snail, only that the feet are to be seen. If deprived of it, it does not survive; and when it is fully developed, the insect becomes a chrysalis. The wild fig-tree produces gnats,153 known as “ficarii;” and the little grubs of the fig-tree, the pear-tree, the pine, the wild rose, and the common rose produce cantharides,154 when fully developed. These insects, which are venomous, carry with them their antidote; for their wings are useful in medicine,155 while the rest of the body is deadly. Again, liquids turned sour will produce other kinds of gnats, and white grubs are to be found in snow that has lain long on the ground, while those that lie above are of a reddish156 colour—indeed, the snow itself becomes red after it has lain some time on the ground. These grubs are covered with a sort of hair, are of a rather large size, and in a state of torpor.