From the Vegalitarian Society (
http://www.vegalitarian.org/pages/Fashion):
Silk is produced by modern factory farm methods which manipulate the lives and bodies of silkworms to obtain their cocoon thread which is transformed into silk textile. The process necessitates boiling, steaming, or baking silkworms to obtain the silk fiber, precipitating a needlessly painful death. Choose rayon, linen, hemp, cotton, or synthetics to boycott this cruelty. The conditions necessary for silk-farming, or sericulture, are outlined by the historical Silkroad Foundation:
"The eggs must be kept at 65 degrees F, increasing gradually to 77 degrees at which point they hatch. After the eggs hatch, the baby worms feed day and night every half hour on fresh, hand-picked and chopped mulberry leaves until they are very fat. Also a fixed temperature has to be maintained throughout. Thousands of feeding worms are kept on trays that are stacked one on top of another. A roomful of munching worms sounds like heavy rain falling on the roof. The newly hatched silkworm multiplies its weight 10,000 times within a month, changing color and shedding its whitish-gray skin several times.
The silkworms feed until they have stored up enough energy to enter the cocoon stage. While they are growing they have to be protected from loud noises, drafts, strong smells such as those of fish and meat and even the odor of sweat. When it is time to build their cocoons, the worms produce a jelly-like substance in their silk glands, which hardens when it comes into contact with air. Silkworms spend three or four days spinning a cocoon around themselves until they look like puffy, white balls.
After eight or nine days in a warm, dry place the cocoons are ready to be unwound. First they are steamed or baked to kill the worms, or pupas. The cocoons are then dipped into hot water to loosen the tightly woven filaments. These filaments are unwound onto a spool. Each cocoon is made up of a filament between 600 and 900 meters long! Between five and eight of these super-fine filaments are twisted together to make one thread . . .
World silk production has approximately doubled during the last 30 years in spite of man-made fibers replacing silk for some uses. China and Japan during this period have been the two main producers, together manufacturing more than 50% of the world production each year. During the late 1970's China, the country that first developed sericulture thousands years ago dramatically increased its silk production and has again become the world's leading producer of silk."