The most important thing to remember in the study of moths and butterflies is that they appear in four different forms during their lives. These forms are:
The egg. The larva. The pupa. The adult.
The Eggs.
The eggs are laid singly or in clusters. They are usually found on the plant which is the favorite food of the young. Look for the shining masses of the eggs of the tent-caterpillar on apple and wild cherry trees; also for the yellow eggs of potato beetles on potato leaves.
The Larva.
The larva or "worm" hatches from the egg. During this period in its history the insect eats and grows. If you doubt that they have good appetites, undertake to feed a few healthy caterpillars this spring. If you doubt that they are particular as to the kind of food they have, find out for yourselves whether the apple tree "worm" will eat milk-weed leaves or whether the milk-weed caterpillar will eat leaves taken from an apple tree.
Fig. 346. Chrys'-a-lids of the mourning-cloak butterfly.
One of the most interesting things to notice in the study of larvæ or caterpillars is that they occasionally appear in bright new coats, and we find the old ones have been cast aside. It is necessity, not pride, that leads them to do this. You see, an insect's skeleton is on the outside of its body; and if it could not be shed once in a while how would there be room for the little creature to grow?