The moth species known for producing the highest-quality commercial silk is Bombyx mori, the domesticated silkworm moth.
Bombyx mori has been bred for silk production in China for thousands of years. Its caterpillars feed mainly on mulberry leaves and spin cocoons made from a continuous filament of fibroin, coated with sericin. People soften and unwind the cocoons to obtain silk thread.
Domestication has made the adult moth highly dependent on human care. It has lost much of its ability to fly, and domesticated strains are generally unable to survive without cultivation. The adult moth has reduced mouthparts and does not feed, relying on resources accumulated during the larval stage.
Several wild silkmoths also produce commercially useful fibers, including eri and tussar silks. However, Bombyx mori remains the principal source of mulberry silk, the smooth, strong, and lustrous silk most associated with traditional sericulture.