. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 36 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. with their old skins, it becomes quite an unpleasant feature in our pub- lic thoroughfares and parks. The caterpillars always feed underneath these webs; but as soon as they approach maturity, which requires about one mouth, they commence to scatter about, searching for suita- ble places in which to spin their cocoons. If very numerous upon the same tree the food-supply gives out, and they are forced by hunger to leave their sheltering homes before the usual time.
. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 36 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. with their old skins, it becomes quite an unpleasant feature in our pub- lic thoroughfares and parks. The caterpillars always feed underneath these webs; but as soon as they approach maturity, which requires about one mouth, they commence to scatter about, searching for suita- ble places in which to spin their cocoons. If very numerous upon the same tree the food-supply gives out, and they are forced by hunger to leave their sheltering homes before the usual time. " When the young caterpillars are forced to leave their webs they do not drop suddenly to the ground, but suspend themselves by a fine silken thread, by means of which they easily recover the tree. Grown caterpillars, which measure inches in length, do not spin such a thread. Both old and young ones drop themselves to the ground with- out spinning when disturbed or sorely pressed by hunger. Fiqja and Cocoon.—" Favorite recesses selected for i^upation are the crevices in bark and similar shelters above ground; in some cases even the empty cocoons of other moths.* The angles of tree-boxes, the rub- bish collected around the base of trees and other like shelter are em- ployed for this purpose, while the second brood prefer to bury them- selves just under the surface of the ground, provided that the earth be soft enough for that purpose. The cocoon itself is thiu and almost transparent, and is composed of a slight web of silk intermixed with a few hairs, or mixed with sand if made in the soil. *' The pupa (Fig. 18, d and e) is of a very dark-brown color, smooth and polished, and faintly punctate; it is characterized by a swelling or bulging about the middle. It is inch long and inch broad in the middle of its body, or where it bulges a little all round, The Moth (Fig. 18, 6).—"The moths vary greatly, both in size and coloration. They have, in conse
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