210 LEPIDOPTERA 



soon as they begin to feed. The bag is made of silk mixed 

 with the bits of leaf, etc., and attached to the twig by silken 

 threads. The metamorphosis to the pupal stage occurs 

 within the case. There is a marked difference in the size, 

 etc., of the males and females in the case. They are a 

 source of injury to evergreen trees, stripping the foliage. 

 They are a little difficult to contend with. Applications 

 of poisonous arsenical solutions to the foliage where they 

 are feeding will kill them. The cocoons may be gathered 

 and destroyed. The migration from tree to tree is limited 

 by the migration of the larvse, as the females remain in the 

 bag and do not travel about. The migrations of the cater- 

 pillars are limited to rather short distances. This is the best- 

 known species of the family. 



Family Cossidae. — The family Cossidce is another group 

 presenting adaptations to special food and includes the 

 carpenter moths — characterized by the wood-boring habit 

 of the larvse. This is a decided departure from the leaf-feed- 

 ing habit. The leaf-feeding habit is the most primitive 

 condition. They burrow into the heart-wood of various 

 trees. 



Locust-tree Borer (Prioiwxystvs rohmioe). — The locust-tree 

 borer is the most conspicuous. It occurs in other trees 

 besides the locust. The moths are strong-bodied and 

 resemble the hawk moths in the shape of the body and in the 

 narrow form of the wings. The adidts appear in June and 

 July and deposit their eggs upon various trees and the larvse 

 on hatching begin burrowing into the tree, living at first 

 in the cambium and then burrowing deeper into the woody 

 tissue. The larvae are supposed to require three years for 

 their growth. The larva is whitish and almost naked with 

 only a few^ scanty, minute hairs and looks more like the 

 grub of a beetle than like a caterpillar of a moth. It forms 

 a rather large tunnel, the burrow when the larva gets full 

 size being about one-half inch. These burrows frequently 

 permit the entrance of moisture and so start decay and in 

 m^any cases cause some distortion; they cause trees to break 

 easily. Before changing to the pupal stage they bore out to 



