Let us fancy the egg of our _Troilus_ fastened--a fairy cradle, indeed--on the leaf of a wild cherry tree that has tossed its sprays of feathery white bloom, and its rustling leaves all June long in sunshine and wind and twinkling shower beneath a summer sky. When the shell is broken, what a strange thing creeps forth!--well-named a larva or _mask_, for it is a disguise that has no trace of a winged nature. The lover of the butterfly shrinks with loathing from this hideous creature, dragging itself slowly along in quest of the food which it greedily devours--the fresh, sweet leaves of the tree that has sheltered it! But unless it eats and grows there will be no butterfly, and sometimes the skin is cast off as many as five or six times, even the inner lining as well as the outside skin, to give its growth free play. If the caterpillar were large it would be terrible, for it protects itself, being soft-skinned and often helpless, by a mimicry of rage, pawing the ground, lashing its head furiously from one side to another, as a lion lashes its tail, rearing itself up menacingly in a sphinx-like attitude, grinding its mandibles with a grating sound. Its color is at first usually green like the leaf it feeds on, but it afterwards develops bright hues in some species. The _Troilus_ caterpillar is green with a yellow stripe on each side, and row of blue dots, while its under side and feet are reddish. These varied colors show little, however, on the tree, for the leaves of fruit-trees, especially, quickly assume a yellow tint, and are streaked and spotted. Caterpillars protect themselves in many ways; some make a tent of a leaf near their feeding-ground, turning over an edge under which they creep, or weaving the different corners of the leaf closely together with silken threads. Even the petals of a blossom may be secured by a filmy web. If the caterpillar must spend the winter as a caterpillar, it makes of the leaf a winter-house, which it covers with wood-colored silk, and weaves the thread securely to the skin. These nests resemble closely the buds of the tree.