Sericulture, the technique of silk production, is an agro-industry, playing an eminent role in the rural economy of India. Silk-fibre is a protein produced from the silk-glands of silkworm.
The systematic cultivation of mulberry, the food plant of silk worm (Bombyx mori), is the first step in the production of mulberry silk.
In India(Karnataka state), where the temperature ranges from 16-31 degree centigrade, enjoys favourable climatic conditions for rearing the silkworm throughout the year. Of a life span of 50 days of the silkworm, the egg stage lasts 10 days, the larval stage lasts longest-25-30 days. The pupa stage takes 10 days. The silkworm pass 4 moults during growth.
The cocoons are cooked in hot water & the silk fibre is unwound from the cocoons.This process is called ‘reeling’. The silk consists of two proteins, the inner core of fibroin & an outer cover of gum sericin. During reeling, the cocoons are processed in hot water at 95-97 degree centigrade for 10-15 minutes. This process is called cooking. This cooking will enable the sericin portion to get softened & make unwinding easy without breaks.
Text above courtesy : http://www.krishiworld.com/html/seri_ind1.html
Personally it is appalling that so many living creatures are to lose their lives for our indulgence. Typically 1500 cocoons are needed to produce 1 mtr of woven silk fabric. More recently there is a more eco-friendly variety of silk that does not kill the worms but instead lets the silkworm turn into silk moth and use the cocoons that are left behind.