The Silkworm

The silkworm is the larva or caterpillar of the domesticated silkmoth, Bombyx mori (Latin: 'silkworm of the mulberry tree'). It is an important economic insect since it is the producer of silk. A silkworm's preferred food is white mulberry leaves, but it may also eat the leaves of any other mulberry tree as well as the Osage Orange. It is entirely dependent on humans for its reproduction and does not occur naturally in the wild. Sericulture, the practice of breeding silkworms for the production of raw silk, has been underway for at least 5,000 years in China, from where it spread to Korea and Japan, and later to India and the West. Eggs take about fourteen days to hatch into larvae, which eat continuously. They have a preference for white mulberry, having an attraction to the mulberry oderant cis-jasmone. They are not monophagous since they can eat other species of Morus as well as some other Moraceae. Hatchlings and second-instar larvae are called kego and chawki in India. They are covered with tiny black hairs. When the color of their heads turns darker, it indicates that they are about to molt. After molting, the instar phase of the silkworm emerges white, naked, and with little horns on the backs. After they have molted four times (in the fifth instar phase), their bodies become slightly yellow and the skin become tighter. The larvae will then enter the pupa phase of their life cycle and enclose themselves in a cocoon made up of raw silk produced by the salivary glands. The cocoon provides a vital layer of protection during the vulnerable, almost motionless pupal state. Many other Lepidopteraproduce cocoons, but only a few—the Bombycidae, in particular the Bombyx genus, and the Saturniidae, in particular the Antheraea genus—have been exploited for fabric production. If the animal is allowed to survive after spinning its cocoon and through the pupa phase of its life cycle, it will release proteolytic enzymesto make a hole in the cocoon so that it can emerge as a moth. These enzymes are destructive to the silk and can cause the silk fibers to break down from over a mile in length to segments of random length, and ruins the silk threads. To prevent this, silkworm cocoons are boiled. The heat kills the silkworms and the water makes the cocoons easier to unravel. Often, the silkworm itself is eaten.During the life cycle the moth cannot fly.Silkmoths have a wingspan of 3–5 cm and a white hairy body. Females are about two to three times the bulkier than males (for they are carrying many eggs), but are similarly colored. Adult Bombycidaes have reduced mouth parts and do not feed, though a human caretaker can also feed them.