Silk
Silk moths lay eggs on specially prepared paper. The eggs hatch and the caterpillars (silkworms) are fed fresh mulberry leaves. After about 35 days and 4 moltings, the caterpillars are 10,000 times heavier than when hatched and are ready to begin spinning a cocoon. A straw frame is placed over the tray of caterpillars, and each caterpillar begins spinning a cocoon by moving its head in a pattern. Two glands produce liquid silk and force it through openings in the head called spinnerets. Liquid silk is coated in sericin, a water-soluble protective gum, and solidifies on contact with the air. Within 2–3 days, the caterpillar spins about 1 mile of filament and is completely encased in a cocoon. The silk farmers then heat the cocoons to kill them, leaving some to metamorphose into moths to breed the next generation of caterpillars. Harvested cocoons are then soaked in boiling water to soften the sericin holding the silk fibers together in a cocoon shape. The fibers are then unwound to produce a continuous thread. Since a single thread is too fine and fragile for commercial use, anywhere from three to ten strands are spun together to form a single thread of silk.
Entomophagy
Cave paintings in Altamira, north Spain, which have been dated from about 30,000 to 9,000 BC, depict the collection of edible insects and wild bee nests, suggesting a possibly entomophagous society. Cocoons of wild silkworm ("Triuncina religiosae") were found in ruins in the Shanxi province of China, from 2,000 to 2,500 years BC. The cocoons were discovered with large holes in them, suggesting the pupae were eaten. Many ancient entomophagy practices have changed little over time compared with other agricultural practices, leading to the development of modern traditional entomophagy.