THE LARCH CASE-BEARER 



43 



When the larvae enter hibernation in the fall they are very small and 

 only about one fourth to one third grown. Their cases at this time are 

 long and slender, for each case is merely a piece of a mined leaf from the 

 larch. The cases are nearly cylindrical, for, although the leaves of the 

 larch are flat, the body of the larva evidently fills out the hollow leaf 

 and makes it cylindrical. The outer, or free, end of the case is usually 

 slightly contracted and fully closed with a sheet of silk. The other end 

 of the case is securely attached to the branch with a copious supply of 

 silk. Some of the cases lie flat along the branch, while others project at 

 various angles as shown in Figs. 5 and 1 2 . Very often the cases occur in 



FIG. 5. Hibernating case-bearers, natural size 



bunches of four or five clustered in the axil of a bud. The winter cases 

 vary considerably in length, measuring all the way from one eighth to 

 one sixth of an inch. 



In the fall of 1910 the majority of the larvae did not migrate from the 

 leaves to the branches until the latter part of October. On October 24 

 most of them were still actively feeding on the leaves, but a few had moved 

 down to the branches. By October 31 the great majority had established 

 themselves in their winter quarters. Here they remained until the fol- 

 lowing April, nearly six months, in a perfectly quiescent condition. 



The case-bearers in spring 



As soon as the buds of the larch begin to put out in the spring, the case- 

 bearers wake from their long winter's sleep and migrate to the buds (Fig. 1 1) . 



