at which stage does a silkworm produce silk thread
Sericulture Silkworm larvae are fed with mulberry leaves, and, after the fourth moult, they climb a twig placed near them and spin their silken cocoons. The silk is a continuous filament comprising fibroin protein, secreted from two salivary glands in the head of each larva, and a gum called sericin, which cements the filaments. 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.[8] The immersion in hot water also kills the silkworm pupa.
Dental floss Levi Spear Parmly, a dentist from New Orleans, is credited with inventing the first form of dental floss.[4] In 1819, he recommended running a waxen silk thread "through the interstices of the teeth, between their necks and the arches of the gum, to dislodge that irritating matter which no brush can remove and which is the real source of disease."[5][6] He considered this the most important part of oral care.[4] Floss was not commercially available until 1882, when the Codman and Shurtleft company started producing unwaxed silk floss.[7] In 1898, the Johnson & Johnson Corporation received the first patent for dental floss that was made from the same silk material used by doctors for silk stitches.[7]