The three kinds of materials we use mostly for our clothes are cotton, wool, and silk. We get these useful materials from very different sources. The cotton we get from a plant; wool we get from an animal, the sheep; and silk we get from an insect, the silkworm.
The silkworm is a caterpillar, which changes into a small white moth. The life of all moths and butterflies is the same. The full-grown butterfly or moth lays eggs. These eggs hatch out into caterpillars that crawl about like worms and feed on the leaves of plants. After a time, the caterpillar shuts itself up in a covering which it makes for itself out of its own body, called a chrysalis or a cocoon. There it lies asleep for weeks; but at last, it breaks its prison open, and comes out as a winged insect-a butterfly or a moth. Now the silkworm makes its cocoon of very fine, smooth, shining threads, and these threads are what we call silk, which men weave into silk cloth.
Just as the farmer breeds and rears sheep for the sake of their wool, or grows cotton plants for the sake of cotton, so people in China, Japan and India in the East, and in Italy and France in the West, breed, and rear these caterpillars, called silkworms, for the sake of silk. They keep regular silkworm farms, which are planted with mulberry trees, for it is on the leaves of these trees that the silkworms feed.
The silkworm moth lay their eggs in August or September, and the eggs are hatched the following May (when the mulberry trees come into leaf) into small caterpillars. These caterpillars feed greedily for about a month; and then when they are about three inches long, they spin their yellow silk cocoons, and go to sleep. These cocoons, when finished are placed in an oven, the heat of which kills the caterpillars inside; and then the silk threads of which they are made are unwound and afterward woven into beautiful shining silk cloth.