Wild silk

Wild silks have been known and used in many countries from early times, although the scale of production is far smaller than that from cultivated silkworms.

Wild silk should not be confused with the very rare sea silk, which is produced from the fibres or byssus produced by the seashell Pinna nobilis and related species.

Commercially reared silkworms of the species Bombyx mori (Linnaeus, 1758) are normally killed before the pupae emerge, either by pricking them with a needle or dipping the cocoons into boiling water, thus allowing the whole cocoon to be unravelled as one continuous thread. This allows a much finer cloth to be woven from the silk.

There are more than 500 species of wild silkworms in the world, although only a few are used to produce cloth. They usually produce a tougher and rougher silk than that from domesticated Bombyx mori silkworms. Wild silks are usually harvested after the moths have left the cocoons, cutting the threads in the process, so that there is not one long thread, as with domesticated silkworms.

Wild silks are more difficult to bleach and dye than silk from Bombyx mori, but most have naturally attractive colours, particularly the rich golden sheen of the silk produced by the muga silkworm from Assam, often known as Assam silk.

The cocoon shells of wild silk moths are toughened or stabilized either by tanning (cross-linking) or by mineral reinforcements (e.g. calcium oxalate). Recently, a new method has been developed, demineralizing, which can remove the mineral reinforcements present in wild silks and enables wet reeling like the commercial silkworm Bombyx mori.

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).

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Wikipedia