[Illustration: _Fig. 348. The cecropia pupa inside the cocoon. Nearly natural size._] Let us next look at the pupa of a moth. This is often inside a covering which is called a cocoon. If you look on the fruit trees or shade trees about your home you may find a cocoon of the ce-cró-pi-a moth. You will see that it is made of silk. This covering was spun by the giant silkworm as a protection against the storms of winter. How snug the pupa is inside, and how firmly the cocoon is fastened to the twig on which you found it! Figs. 347, 348, 349 show this interesting insect. When you are studying pupæ remember that butterflies do not come out of cocoons. Their chrysalis or pupa is always uncovered. In the case of moths, however, the pupa is either inside a cocoon or protected by being underground or in some well sheltered place. These facts suggest a question. Is there any reason why the one should be better fitted to endure cold and storms than the other? THE ADULT. We now come to the fourth period in the lives of moths and butterflies, a period which has ever had and ever will have an interest for young and old. Since there are many persons, little and big, who cannot distinguish the two groups, butterflies and moths, let us learn the marks by which they may be known. [Illustration: _Fig. 349. Cecropia moth just emerged from the cocoon, on which it hangs. The moth comes from the pupa._] Butterflies have uncovered pupæ. They fly by day. The wings are folded over the back when at rest. The antennæ or feelers have _knobs_ on the ends. (Fig. 350 B.) The body is slender. Moths have pupae either inside cocoons or protected by being underground or in some sheltered place. Many moths fly at night. The antennæ are never knobbed. (Fig. 350 M M.) leave the wings spread when they are at rest. The body is stout. Occasionally you may come across insects that very closely resemble butterflies, yet have some characters that are similar to those of moths. They are the skippers, so named because of their strong and rapid flight. The antennæ have knobs, but these knobs are drawn out and turned back in the form of a hook. (Fig. 350 S.) The body is rather stout. The pupa is covered by a thin cocoon. In some species the wings are held vertically, in others horizontally. SUGGESTIONS FOR STUDY. Cocoons and butterfly chrysalids are very hard to find because they so closely resemble the withered leaves that cling to shrubs and trees. [Illustration: _Fig. 350. Antennæ or feelers._]