70 Annals Entomological Society of America [Vol. IV, 



larva is packed behind it in the mine. Here the larvae live 

 until September. Owing to our absence from the University 

 during the first part of September, we are unable to say at just 

 what date the larvae first began to leave their mines and 

 make their cases. On my return on the loth of September 

 many of them were found in their tiny cases feeding on the 

 leaves. From this time on through September opportunity 

 was given to observe them making their cases. In most 

 instances, at least, they clean out their mines and pack the 

 excrement in the outer end of it near the tip of the leaf. When 

 the burrow is clean enough to suit them they cut off the tip 

 of the leaf containing the excrement, which falls to the ground 

 out of the way, and then they cut off enough of the leaf contain- 

 ing the clean part of the mine to make them a case of the desired 

 length. The larvae now feed on the leaves of the larches until 

 the latter part of October when they migrate to the branches 

 and go into hibernation. 



