“SOONER or later, according to its species, a day comes when the larva feels itself strong enough to face the perils of metamorphosis. It has valiantly done its duty, since to stuff its paunch is the duty of a worm; it has eaten for two, itself and the matured insect. Now it is advisable to renounce feasting, retire from the world, and prepare itself a quiet shelter for the death-like sleep during which its second birth takes place. A thousand methods are employed for the preparation of this lodging.

“Certain larv? simply bury themselves in the ground, others hollow out round niches with polished sides. There are some that make themselves a case out of dry leaves; there are others that know how to glue together a hollow ball out of grains of sand or rotten wood or loam. Those that live in tree-trunks stop up with plugs of sawdust both ends of the galleries they have hollowed out; those that live in wheat gnaw all the farinaceous part of the grain, scrupulously leaving untouched the outside, or bran, which is to serve them as cradle. Others, with less precaution, shelter themselves in some crack of the bark or of a wall, and fasten themselves there by a string which goes round their body. To this number belong the caterpillars of the cabbage butterfly and the swallow-tail. But especially in the making of the silk cell called cocoon is the highest skill of the larv? shown.

Silk Worm
Eggs, worm, cocoon, and butterfly

“An ashy white caterpillar, the size of the little finger, is raised in large numbers for its cocoon, with which silk stuffs are made. It is called the silkworm. In very clean rooms are placed reed screens, on which they put mulberry leaves, and the young caterpillars come from eggs hatched in the house. The mulberry is a large tree cultivated on purpose to nourish these caterpillars; it has no value except for its leaves, the sole food of silkworms. Large tracts are devoted to its cultivation, so precious is the handiwork of the worm. The caterpillars eat the ration of leaves that is frequently renewed on the screens, and from time to time change their skin, according to their rate of growth. Their appetite is such that the clicking of their jaws is like the noise of a shower falling during a calm on the foliage of the trees. It is true that the room contains thousands and thousands of worms. The caterpillar gets its growth in four or five weeks. Then the screens are set with sprigs of heather, on which the worms climb when the time comes for them to spin their cocoons. They settle themselves one by one amid the sprigs and fasten here and there a multitude of very fine threads, so as to make a kind of network which will hold them suspended and serve them as scaffolding for the great work of the cocoon.

“The silk thread comes out of the under lip, through a hole called the spinneret. In the body of the caterpillar the silk material is a very thick, sticky liquid, resembling gum. In coming through the opening of the lip, this liquid is drawn out into a thread, which glues itself to t............