CHAP. 41. (35.)—MOTHS, CANTHARIDES, GNATS–AN INSECT THAT BREEDS IN THE SNOW.

Dust, too, is productive of worms[1] 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 mois- ture, 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,[2] 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,[3] when fully developed. These insects, which are venomous, carry with them their antidote; for their wings are useful in medicine,[4] 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 reddish[5] 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.

1. These are really the larvæ of night-moths. His account here is purely imaginary.

2. He speaks of the Cynips psenes of Linnæus, which breeds on the blossom of the fig-tree, and aids in its fecundation. See B. xv. c. 21.

3. He alludes to various coleopterous insects, which are not included among the Cantharides of the modern naturalists. They are first an egg, then a larva, then a nympha, and then the insect fully developed.

4. See B. xxix. c. 30.

5. The redness sometimes observed on the snow of the Alps and the Pyrenees, is supposed by De Lamarck to be produced by animalculæ: other naturalists, however, suppose it to arise from vegetable or mineral causes.