Sericulture, or silk farming, is the rearing of silkworms for the production of silk. Although there are several commercial species of silkworms, Bombyx mori is the most widely used and intensively studied silkworm. According to Confucian texts, the discovery of silk production B. mori dates to about 2700 BCE, although archaeological records point to silk cultivation as early as the Yangshao period (5000 – 3000 BCE). By about the first half of the 1st century CE it had reached ancient Khotan, and by CE 140 the practice had been established in India. Later it was introduced to Europe, the Mediterranean and other Asiatic countries. Sericulture has become one of the most important cottage industries in a number of countries like China, Japan, India, Korea, Brazil, Russia, Italy and France. Today, China and India are the two main producers, together manufacturing more than 60% of the world production each year.
Silkworm larvae are fed by mulberry leaves, and, after the fourth moult, climb a twig placed near them and spin their silken cocoons. This process is achieved by the worm through a dense fluid secreted from its structural glands, resulting in the fibre of the cocoon. The silk is a continuous-filament fiber consisting of fibroin protein, secreted from two salivary glands in the head of each larva, and a gum called sericin, which cements the two filaments together. The sericin is removed by placing the cocoons in hot water, which frees the silk filaments and readies them for reeling. This is known as the degumming process. The immersion in hot water also kills the silkworm pupae.
Single filaments are combined to form thread. This thread is drawn under tension through several guides and wound onto reels. The threads may be plied together to form yarn. After drying the raw silk is packed according to quality.
Stages of production
The stages of production are as follows:
- The silk moth lays thousands of eggs.
- The silk moth eggs hatch, and the larvae feed on the mulberry leaves.
- When the silkworms are about 10,000 times heavier than when they hatched, they are now ready to spin a cocoon.
- The silk is produced in two glands in the silkworm's head and then forced out in liquid form through the spinnerets.
- The silk solidifies when it comes in contact with the air.
- The silkworm spins approximately 1 mile of filament and completely encloses itself in a cocoon in about two or three days but due to quality restrictions, the amount of usable silk in each cocoon is small. As a result, 5500 silkworms are required to produce 1 kg of silk.
- The silk is obtained from the undamaged cocoons by brushing the cocoon to find the outside end of the filament.
- The silk filaments are then wound on a reel. One cocoon contains approximately 1,000 yards of silk filament. The silk at this stage is known as raw silk. One thread consists of up to 48 individual silk filaments.
As the process of harvesting the silk from the cocoon kills the larvae, sericulture has been criticized by animal welfare and rights activists. Mahatma Gandhi was critical of silk production based on the Ahimsa philosophy "not to hurt any living thing". This led to Gandhi's promotion of cotton spinning machines, an example of which can be seen at the Gandhi Institute. He also promoted Ahimsa silk, wild silk made from the cocoons of wild and semi-wild silk moths. Ahimsa silk is promoted in parts of Southern India for those who prefer not to wear silk produced by killing silkworms. Ahimsa silk is also known as peace silk. In the early 21st century the organisation PETA has campaigned against silk.
- Barber, E. J. W. (1992). Prehistoric textiles: the development of cloth in the Neolithic and Bronze Ages with special reference to the Aegean (reprint, illustrated ed.). Princeton University Press. p. 31. ISBN 978-0-691-00224-8. Retrieved 06-11-2010.
- Hill, John E. 2003. "Annotated Translation of the Chapter on the Western Regions according to the Hou Hanshu." 2nd Draft Edition. Appendix A.
- "History of Sericulture". Governmentof Andhra Pradesh (India) - Department of Sericulture. Retrieved 7 November 2010.
- Bezzina, Neville. "Silk Production Process". Sense of Nature Research.
- "Mahatma Gandhi: 100 years", 1968, p. 349
- Silk Moths Fly Free Kusuma Rajaiah's Ahimsa project.
- Silk saree without killing a single silkworm Another article about Rajaiah and his methods.
- "Down and Silk: Birds and Insects Exploited for Fabric". PETA. Retrieved 6 January 2007.
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