Cocoon

A cocoon is a shell made of silk by most kinds of moth caterpillars and other insect larvae. Some butterfly larvae (in the family Hesperiidae and subfamilies Parnassiinae and Satyrinae) do spin cocoons.[1] However, most butterfly pupae are called chrysalids.[1] Some caterpillars attach small twigs or pieces of vegetation to the outside of their cocoon to hide it from predators. Others spin their cocoon in a hidden place. Examples would be on the underside of a leaf, in a crevice, or down near the base of a tree trunk.

Silkworm cocoons are processed and used to produce natural silk for clothing.

References

en:Pupa#Cocoon

ms:Pupa#Kokun