Hobbies And Interests
Diet
For centuries in China and Japan, feeding silkworms was a closely guarded secret. Silkworms eat only the leaves from Asian mulberry trees. You can feed an artificial, commercial diet made of mulberry leaves to silkworms if fresh mulberry leaves are not available. In Colonial Virginia during the 1600s, the colonists tried to feed imported silkworms leaves from North American mulberry trees, but the silkworms would not eat them. As a result, the first silk industry in the New World failed.
Cocoons
To harvest silk, the cocoons are boiled, which kills the silkworm and also eliminates the sticky substance -- called "sericin" -- that helps to bind the cocoon together. When unraveled, a silkworm cocoon is about 914 meters or just under 2,999 feet long. It takes 3,000 cocoons to produce just one pound of silk. The thread from one cocoon is too fragile to weave, so threads are spun together to make a thread strong enough to use.
Adult Silk Moths
Adult silk moths are hairy, a white powdery color and about 50 millimeters long. The silk moth is completely dependent on people for its continued existence. After 5,000 years of domestication, adult silk moths can no longer fly although they still have wings and can crawl for about 12 inches. The males crawl more than females in their search for mates. Females produce scent chemicals called pheromones that lead the males to them. Adult moths live a few weeks and mate. The female lays about 500 eggs before dying.
Molting
Silkworms hatch about 20 days after the female moths lay their eggs. In between hatching from their eggs and spinning their cocoons, silkworms go through four molts, called "instars." With each molt, the silkworm climbs out of its old body and emerges into a slightly larger body. Silkworms eat as much as possible for 25 days and then suddenly stop eating in preparation for spinning their cocoons.