Page:Popular Science Monthly Volume 27.djvu/264

250 they are "stung" by minute four-winged flies, parasites upon these tiny objects.

One of the most curious things about the laying of moth-eggs is the botanical knowledge of the mother-moth. In the dark she knows the particular trees upon which her brood flourish, out of a whole forest. The proverb about one man's meat being another man's poison holds good when applied to the caterpillars of moths. They will starve, as a rule, before eating, or die upon eating, the wrong kind of leaves. The little eggs, sown here and there by the mother-moth in her nocturnal flights, are often very pretty to look at through the microscope, being adorned with delicate traceries. Some kinds are nearly smooth, as those of the Cecropia, which are quite easily found on lilac and other leaves, gummed on, with a little brown spot above, over the micropyle, through which the curled-up caterpillar within, a little black, thorny creature, escapes. Some caterpillars eat the empty egg-shell for their first meal, but the practice is far from general. Some which I particularly noticed, those of the "chestnut-stripe" or honeysuckle-leaves, only nibble at the empty egg-shell, and, I thought, were attracted by some of the softer parts which might remain. The caterpillars of this moth (Homohadena badistriga) afterward make a rather stout cocoon; I have reared them from eggs found in the back-yard of a house in the heart of New York city. So far do our country friends penetrate.

The bodies of caterpillars and moths are made up of segments, or rings, hardened by a substance called chitine, so that it has been said that insects really follow out Sydney Smith's suggestion, given under exceptional circumstances, and "sit in their bones" the whole time. They strike against the outside world with the knobby parts of their anatomy. A child once described a caterpillar as a "jointed tube, filled with soft stuff." I don't know how she found out about the "soft stuff," but the insides are soft, and, when carefully examined, show the respiratory canals, opening by little narrow slits in the sides of the segments (for insects do not breathe by the mouth), the nervous and the muscular systems, networks of little whitish threads, as also the central digestive apparatus, which takes up the most room, as our caterpillar is principally a feeding animal. The stiffness of the rings of insects is obviated by their being connected by a highly flexible membrane. The caterpillar increases in size by changing its skin. The old covering becomes too small to hold the food which is retained and transformed by the chemistry of the body into caterpillar-flesh. It splits behind the head, and, with more or less trouble, the caterpillar frees itself from it, stepping out, and leaving its old skin, a thin and almost colorless pellicle, to be blown by the summer winds into Nature's rag-bags which the spiders mostly carry about.

Caterpillars are of all colors, and, within certain limits, of all sizes, variations of the "jointed tube, with soft insides." They are plain and smooth, or ornamented with tufts of hair, or fleshy, colored humps;