Silk
Silk moths lay eggs on specially prepared paper. The eggs hatch and the caterpillars (silkworms) are fed fresh mulberry leaves. After about 35 days and 4 moltings, the caterpillars are 10,000 times heavier than when hatched and are ready to begin spinning a cocoon. A straw frame is placed over the tray of caterpillars, and each caterpillar begins spinning a cocoon by moving its head in a pattern. Two glands produce liquid silk and force it through openings in the head called spinnerets. Liquid silk is coated in sericin, a water-soluble protective gum, and solidifies on contact with the air. Within 2–3 days, the caterpillar spins about 1 mile of filament and is completely encased in a cocoon. The silk farmers then heat the cocoons to kill them, leaving some to metamorphose into moths to breed the next generation of caterpillars. Harvested cocoons are then soaked in boiling water to soften the sericin holding the silk fibers together in a cocoon shape. The fibers are then unwound to produce a continuous thread. Since a single thread is too fine and fragile for commercial use, anywhere from three to ten strands are spun together to form a single thread of silk.
Wild silk
Wild silks are often referred to in India as 'Vanya' silks: The term 'Vanya' is of Sanskrit origin, meaning untamed, wild, or forest-based. Muga, Tasar, and Eri silkworms are not fully tamed and the world lovingly calls the silks they produce as 'wild silks'.
India produces four kinds of silk: mulberry, tasar, muga and eri. The silkworm "Bombyx mori" is fed on mulberry leaves cultivated in plantations. Silkworms are also found wild on forest trees, e.g "Antheraea paphia" which produces the tasar silk (Tussah). "Antheraea paphia" feeds on several trees such as "Anogeissus latifolia", "Terminalia tomentosa", "T. arjuna" ("Terminalia arjuna"), "Lagerstroemia parviflora" and "Madhuca indica". Wild silkworm "Antheraea assamensis" produces muga silk, and another wild silkworm "Philosamia synthia ricini" (= "Samia cynthia") produces eri silk. The estimated annual production of tasar silk is 130 tonnes. Production of other types of silk exceeds 10 000 tonnes (Gupta 1994).
In 2015, Adarsh Gupta K of Nagaraju's research team at Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India, discovered the complete sequence and the protein structure of Muga Silk Fibroin and published it in "Scientific Reports".