Silk

Silk forms the base of Bhagalpur economy. The artisans at and around Bhagalpur are traditionally silk fabric weaver since few hundred years.

Origin of Silk

Historians say, culture & use of Silk originates 4000 years back.The empress Si-Ling-Chi learned how to rear the caterpillars on mulberry leaves and how to unwind the silk from cocoons.

The secret of silk-making was kept close by the Chinese and was somehow smuggled into Japan early in the Christian era and also reached India.

Raw Silk is now extensively produced in China, India, Vietnam, Russia and Japan.

Sericulture

Silk is a strong, soft, lustrous fibre extruded by certain kinds of moth and spiders.

Silkworm eggs are laid out on the mulberry leaves to hatch out into caterpillars about 2 mm long. They grow rapidly, eat voraciously and end up about 30 mm long after 4-5 weeks. During this time, they change skins 4 times. After final skin change, straw frames are provided in which silkworms makes its cocoon. Cocoon-making takes further 8 days, It takes the silkworm another 3-4 days to transform into pupa and another 15 days for the moth to emerge. Like all other moths, the insect passes through four stages in it's life : Egg, Caterpillar, Pupa and perfect insect. Female moth lays 200-500 eggs at a time, normally in the summer.

Twin silk threads are extruded through two glands together with a gummy substance which binds the filaments together as well as forms the walls of cocoon. By moving its head from side to side, the silkworm lays the filament gradually building from wall to wall. The gummy substance sets hard and cocoon develops into a shape like peanut with the pupa inside.

Silk Varieties

India basically produces following varieties of Silk:

The main production centres being the states of Karnataka, West Bengal, Madhya Pradesh, Orissa, Bihar, Maharastra, Assam and to some extent Kashmir.

Tussar Silk

Tussar Silk is produced by the larvae of several species of moth. The insects mostly live in the wild on bushes and trees on which they feed. Tussar silk is spun by the worm in a single-shelled, oval cocoon, with a fine-grained, hard, non-flossy shell. The cocoons are generally yellow or grey and are hard & compact.

The cocoons are boiled in chemical solution or treated with enzyme to soften. Thereafter yarn is reeled either in dry process (by drying the cocoons) or by wet reeling process.

The portion of Tussar cocoons leftover after about 60% reelable silk is spun into Katiya yarn.

The pierced cocoons are spun into Ghicha yarn while peduncles are utilised for production of Balkal yarn.