Sericulture
Sericulture is the rearing of silkworms for the production of raw silk. Although there are several commercial species of silkworms, Bombyx mori is the most widely used and intensively studied. According to Chinese records, the discovery of silk production from B. mori occurred about 2,700 B.C Today, China and Japan are the two main producers, together manufacturing more than 50% of the world production each year.
Production
Silkworm larvae are fed cut-up mulberry leaves and after the fourth molt climb a twig placed near them and spin their silken cocoons. The silk is a continuous-filament fiber consisting of fibroin protein secreted from two salivary glands in the head of each larvae, and a gum called sericin, which cements the two filaments together. The sericin is removed by placing the cocoons in hot water and this frees silk filaments ready for reeling. The immersion in hot water also kills the silkworm larva. Single filaments are combined to form yarn. This yarn is drawn under tension through several guides and wound onto reels. Finally, the yarn is dried, and the now raw silk is packed according to quality.
In South Africa, a new method of sericulture has been produced under the leadership of South African-born Ronel Swart. Swart, who grew up fascinated by silkworms, went to work on a silk farm in China for two years after her studies. She brought back the basics of sericulture to her country and began a silk farm in South Africa. Using Swart's method, the cocoons are not boiled with the larvae inside, but are immersed in hot water once the moth has emerged. All the moths that emerge from cocoons in Swart's silk farm are allowed to continue their natural reproductive cycle, and no insects are killed. The silk of the empty cocoon, once broken down by the alkali secreted by the moth, cannot be used in the reeling process used to make the fine silk normally associated with sericulture. Instead, these cocoons are brushed and stretched and a rough thread is spun by hand by rural African women. This is then handwoven or knitted to produce uniquely textured rugs, clothing, scarves, shoes, and the like. The company, Africa Silks, has thrived using this new approach to sericulture, which some view as more nature-friendly. It is also gaining popularity amongst visitors to South Africa.