434 THE INSECT WORLD. 



which they leave occasionally for a few moments. Sometimes these 

 cases contain several larvae. Fig. 42 1 represents the various states 

 of a Hydropsyche; the larva is seen on the left, the pupa on the right, 

 the winged insect in the middle. Two of the insect's tents, or places 

 of shelter, are represented below. Fig. 422 shows the different states 

 of Rhyacophilus vulgatus, larva, cocoon, pupa, and imago. The 

 genus Rhyacophilus has this peculiarity, that the larva spins itself a 

 cocoon in the interior of its dwelling before changing into a pupa. 



