The picture shows the life cycle of silkworm. Altogether there are four stages.
First of all, a moth produces several eggs and after ten days’ growth each egg becomes a silkworm larva that feeds on mulberry leaf. This stage will last four to six weeks, and after which the larva begin to produce a cocoon of silk thread around itself. It will take three to eight days for each larva to form a whole round cocoon. After a period of sixteen days moths unthread from these cocoons. Another life circle then begins again.
The cocoons are used to produce silk cloth. Firstly, people will select qualified cocoons as the raw material. Then these cocoons will be boiled in water in order to unwind the threads. Usually each thread is about 300-900 meters long. After this key stage, the unwound threads now can be dyed to different colors. Then they can be weaved to silk fabric now.