What is meant by the term rearing of silk worms?

Cultivation of silkworms for the purpose of harvesting the silk from their cocoons.

Silkworms eggs take about ten days to hatch. They eat continuously. They have a preference for White Mulberry having an attraction to the mulberry oderant cis-jasmone.

After they have molted four times (i.e., in the fifth instar), their bodies turn slightly yellow and their skin becomes tighter. The larvae enclose themselves in a Cocoon of raw silk produced in the salivary glands that provides protection during the vulnerable, almost motionless pupal state.

The cocoon is made of a thread of raw silk from 300 to about 900 meters (1,000 to 3,000 feet) long. The fibers are very fine and lustrous, about 10 micrometers (1/2,500th of an inch) in diameter. About 2,000 to 3,000 cocoons are required to make a pound of silk.