Silkworms make silk by spewing a substance called fibroin through small holes in their jaws called spinnerets. The spewed-out substance consists of digested leaves and protein produced by the worm. The silkworm produces up to 1200 silken threads within a 72 hour time period, creating a soft, silver cocoon. Once the cocoon process is complete, silk farmers harvest the threads with steam, and the delicate fibers are spun and woven into silk fabrics.
Silkworms use their salivary glands to produce fibroin, and they create their cocoons by rotating repeatedly for up to 72 hours. Each cocoon produces approximately one kilometer of silk fiber. Silk farmers remove the cocoon with steaming water and carefully unwind the cocoon fibers.
Silkworm farmers harvest silkworm eggs by incubating them until they hatch into caterpillars. The larvae are fed mulberry leaves and lettuce for approximately six weeks. While silkworms feed on a variety of plant life, their favorite meal is mulberry leaves. Silkworm larvae that is fed only mulberry leaves during the feeding process are known to produce the finest silk on the market. During this time, the silkworm eats 50,000 times its weight in plant materials. Once the silkworm reaches a maximum weight and height, it changes color and prepares to spin its cocoon.