how do silkworms spin cocoons?

define throwing.

Silkworms are the insects which produce a cocoon of silk around themselves as a part of there life cycle. Before producing silk these insects feed on mulberry leaves continuously for many days. They consume around 50,000 times of their initial body weight. After this feeding period they stop eating food and change there color. Now, they are ready to spin cocoons. 

Silkworms have a pair of special salivary glands which are used for the production of silk and it is released through openings called spinnerets on the mouth part of the larva. Silk is produced as a long continuous filament in a period of about 3 to 8 days.The silkworm rotates its body in a figure-8 movement  for around 300,000 times, resulting in the formation of a cocoon and producing a mile of silk filament.

Throwing: Throwing can be defined as the process of creating silk yarn or thread by twisting raw silk into strands which are strong enough for weaving and knitting. It prevents the thread from splitting into its constituent fibers.