Silk

Silk, fiber produced as a cocoon covering by the silkworm, and valuable for its use in fine fabrics and textiles. The silkworm, in fact, is not a worm but a caterpillar. Although cocoon coverings of fiber are made by a large number of insects, only those of the mulberry silk moth, Bombyx mori, and a few other moths closely akin to it, are used by the silk industry. The silk of other insects, notably the spider, is used for certain manufacturing purposes, particularly for the cross hairs of telescopes and other optical instruments. For a description of the life and habits of the silk moth, see Silkworm.