Silk is obtained from which organism?

Bombyx mori, the domesticated mulberry silkworm, is the main source of the world's silk. It is the caterpillar (larva) of the silk moth, which feeds almost entirely on mulberry leaves.

Life cycle of Bombyx mori:

• Egg: the female moth lays about 300 to 500 eggs.
• Larva (caterpillar or silkworm): it feeds on mulberry leaves for about four weeks, moulting four times as it grows.

Pupa: the mature larva spins a cocoon around itself using a continuous silk filament, produced by a pair of modified salivary glands (silk glands). It takes about two to three days to spin the cocoon.

Adult moth: in nature, the moth emerges by breaking the cocoon. In silk production, the cocoons are usually boiled or steamed before this happens, so that the long filament is not broken.

Silk fibre:

• Silk is a natural protein fibre made of two proteins: fibroin, which forms the core of the fibre, and sericin, a gummy protein that binds the fibres together and is removed during processing (degumming).
• A single cocoon can yield a continuous filament several hundred metres long (sometimes up to about 1,500 metres).
• Silk is strong, smooth, lustrous and absorbent.

History:

Silk production began in China thousands of years ago. China kept the method a secret for centuries, and silk was traded along the Silk Road.

Bombyx mori is completely domesticated; it cannot survive in the wild, and the adult moths cannot fly.

Other silk-producing insects in India:

• Tasar silk: Antheraea mylitta (tropical tasar) and Antheraea proylei/pernyi (oak tasar).
• Muga silk: Antheraea assamensis, found only in Assam.
• Eri silk: Samia ricini (Philosamia ricini), which feeds on castor leaves.
• Mulberry silk from Bombyx mori accounts for the largest share of India's silk production.

Why not the other options?

• ✗Apis mellifera is the European honey bee, reared for honey.
• ✗Laccifer lacca (Kerria lacca) is the lac insect, which produces lac, used to make shellac.
• ✗Danaus plexippus is the monarch butterfly, known for its long migrations; it does not produce silk.