Among the commonest treasures brought into the schools by children in the fall or winter are the cocoons of our giant silk-worms. If one has a place to put them where the air is not too warm or dry, no special care will be necessary to keep them through the winter. Out-door conditions must be imitated as nearly as possible. If early in the fall one is fortunate enough to meet one of these giants out for a walk, it is the simplest thing in the world to capture him and watch him spin his marvelous winter blanket. Two members of this family of giant insects are quite common in this state, the largest the Cecropia, called sometimes the Emperor, and the Promethea. [Illustration: _Fig. 87. Cocoon of the Cecropia moth. It sometimes hangs from a twig of a fruit tree._] The Cecropia moth often measures five or six inches across--a veritable giant. Its main color is dusty brown, with spots and bands of cinnamon brown and white. On each wing is a white crescent bordered with red and outlined with a black line. The body is heavy and covered with thick, reddish-brown hairs, crossed near the end with black and white lines. On its small head are two large feathery feelers or antennæ. The Cecropia moth emerges from the cocoon, full grown, in early summer, when out of doors. Those kept in the house often come out as early as March. The eggs are deposited by the adults upon apple, pear, cherry, maple and other shade and fruit trees. Professor Comstock says that the spiny caterpillars which hatch from the eggs in about two weeks, are known to feed upon the leaves of some fifty species of plants. One could therefore hardly make a mistake in offering refreshment to these creatures, since they are anything but epicures. The full-grown caterpillar, having spent the summer eating and growing, with now and then a change of clothes, is often three inches long and an inch in diameter. It is a dull bluish green in color. On its back are two rows of wart-like protuberances (tubercles), some yellow, some red, some blue. As there is nothing else in nature which is just like it, one need have no difficulty in recognizing the Cecropia in its different phases. [Illustration: _Fig. 88. End of cocoon of Cecropia, inside view, showing where the moth gets out._] The cocoon which this giant silk-worm weaves is shown in Fig. 87. It may be found on a twig of some tree in the dooryard, but sometimes on a fence-post or equally unexpected place. Inside the cocoon the brown pupa, alive but helpless, waits for spring. After the moth comes out it is interesting to examine the structure of the cocoon, and to discover how the moth managed to free itself without destroying the silken blanket (Fig. 88).