The traditional color of China is light cocoon yellow.

1. The cocoons produced by each silkworm are slightly different. The first-class cocoon is pure white, regular in shape and thick in quality. Medium cocoon with light yellow spots, incorrect cocoon type and slight donation injury; Inferior cocoon is yellow, damaged and thin.

2. Find a complete cocoon and shake it. If there is noise inside, it can basically be concluded that the silkworm has become a pupa, otherwise it may still be a silkworm. Find a noisy one.

Peel off the messy silk outside.

Soak the cocoon in boiling water for about half an hour. It's best to put one in each cup.

Find a stick as unsmooth as possible and stir it around the cocoon in the cup. Stir for a while and observe the stick carefully to see if there is one or more silk intertwined.

If not, continue to stir until there is. If there is a root, just unplug it, which is generally impossible to break. After breaking, continue to follow the method of 4-5 steps. If you have a few, you can draw every one, and some of them will not work. The remaining one will be the longest, so it's best to make a simple gadget and shake it, otherwise it will kill people. It usually takes about three hours to wind it up.