Silk Moth - Mulberry Silk Moth - Adult Moths

Also called as Mulberry Silk Moth, the insect is completely domesticated. The adult moths do not feed. They fly during night but of course rarely. It is because the wings are weak. The moths are whitish, yellowish or greenish, 2.5 cm long (females larger than males), covered by white scales. Having plumed antennae and nonfunctional mouth parts.

Male moth dies soon after copulation. Female moth lays 300-400 sub spherical, brownish or greenish eggs on the undersurface of mulberry leaves and then dies. Eggs hatch within 2-10 days. The larva is called caterpillar or silk worm. It undergoes 4- 5 moultings to attain full size. The fully grown caterpillar is 7.5 cm long.

A pair of long silk glands develops from salivary glands. They secrete a clear sticky fluid through a narrow pore or spinneret present on hypophaynx. The sticky fluid solidifies to form silk thread or filaments. It is made of protein fibroin. The silk thread is woven around the caterpillar to form cocoon. The thread is sealed by a gummy substance called sericin. This forms an inactive pupa or chrysalis.

In pupa the larval organs are changed to organs of imago. The cocoons are oval, whitish or yellowish. After about a week of their formation, the cocoons are immersed in hot water to kill pupae and loosen silk thread. A single cocoon yields 300-800 m long thread. About 60,000 cocoons are required to get a kilogram of silk. The thread is reeled off. It is raw silk. Karnataka produces the maximum raw silk in India. The same is treated chemically to get finished silk. The raising of silk worms for obtaining silk is called sericulture.

There are four types of silk:

1. Mulberry Silk (creanish) from Bombyx mori feeding on mulberry leaves.
2. Tasar Silk (brown) from Antherea roylei, A. paphia, A. pernyi and A. mylitta feeding on Sal, Arjun, Fig and Oak.
3. Muga Silk (golden yellow) from A. assama feeding on oak and Soon leaves.
4. Eri or Arandi Silk (ceramic) from Attacus or Philosomia ricni feeding on Castor and Papaya.