SMZ1500 Digital Image Gallery
Silkworm Spiracle
Silkworm is the common name for the silk-producing larvae of any of several species of moths. The most celebrated is the common domesticated silkworm Bombyx mori, which was originally cultivated by the Chinese 5,000 years ago.
The larvae feed on leaves of white mulberry, Osage orange, or lettuce, although artificial diets have been developed for modern commercial operations. After six weeks, the silkworm stops eating and spins its cocoon. The larvae possess a pair of specially-modified salivary glands called silk glands. These glands secrete a clear, viscous fluid that is forced through openings -- called spinnerets -- on the mouthparts of the larva. The fluid hardens as it comes into contact with air to become the silk thread. The diameter of the spinneret determines the thickness of the silk thread produced. Each cocoon of yields a strand of silk about 1,000 yards (900 meters) long.
Silkworm moths live only in captivity at present and are grown in commercial operations around the world. All wild populations are extinct, although presumably there are still related species in Asia. Silkworms have been domesticated so long that they have lost the ability to fly and can no longer survive independently in nature.
