The female silk moth lays about 300 to 400 eggs at a time. The eggs hatch and the caterpillars or silkworms emerge. This is called the larval stage. The silkworm feeds on mulberry leaves.
The silkworm secretes fine filaments from two glands on its head. The filaments are made of a protein that hardens to form silk fibres when exposed to air. The silkworm deposits filaments in layers around its body, through figure-of-eight movements of the head, forming a structure called the cocoon. The silkworm takes three to seven days to prepare the cocoon, formed by about 20-39 concentric layers of a single thread.
Inside the cocoon, the silkworm enters the second stage of its life (called the pupa) and then the third and final stage to become an adult moth. Silk threads are obtained from the cocoon of the silkworm.