Some species of _Lepidoptera_ lay some hundreds of eggs, and it is seldom that the number laid by one female is much below a hundred. As already stated, the under surfaces of leaves are generally chosen for the deposit of eggs, but a few of the insects we are considering always select the upper surface for this purpose. Thus the Puss Moth (page 235), and two or three others resembling it, though much smaller, known as the Kittens (page 234), invariably lay them on the upper surface. And this is the more surprising since the eggs of these moths are brown or black, and consequently so conspicuous on the green leaves as to be in danger of being sighted by the numerous enemies of insects. The Hairstreak Butterflies (page 183) afford another exception to the general rule, for their eggs are deposited on the _bark_ of the trees and shrubs (birch, sloe, elm, oak, and bramble) on which their larvae feed. At the moment each egg is laid it is covered with a liquid sticky substance, so that it is immediately glued to the leaf or stem as soon as it is deposited. The sticky substance soon dries, causing the egg to be so firmly fastened in its place that it is often impossible to force it off without destroying it completely. Some of the _Lepidoptera_ deposit their eggs singly, or in small irregular clusters; but by far the larger number set them very regularly side by side, in so compact a mass that it would be impossible to place them on a smaller area without piling one on top of another. This is not accomplished with the aid of the sight, for the insect performing her task with such precision often has her head on one side of a leaf or stem while arranging her eggs on the other. If you take the trouble to watch her, you will see that she carefully _feels_ out a place for each egg by means of the tip of her abdomen immediately before laying it. The eggs are laid by moths and butterflies at various seasons of the year. In some cases they are deposited early in the spring, even before the buds of the food plants have burst; and the young larvae, hatched a few weeks later, commence to feed on the young and tender leaves. Then, throughout the late spring, the whole of the summer and autumn, and even till the winter frosts set in, the eggs of various species are being laid. Those deposited during the warm weather are often hatched in a few days, but those laid toward the autumn remain unchanged until the following spring. In this latter case the frosts of the most severe winter are not capable of destroying the vitality of the eggs. In many instances the perfect insect or the larva would be killed by the temperature of an average winter day, but the vitality of the eggs is such that they have been subjected to a temperature, artificially produced, of fifty degrees below the freezing point, and even after this the young larvae walked out of their cradles at their appointed time just as if nothing unusual had occurred.