THE SEQUOIA PITCH MOTH. 5 



could be collected within the comparatively small area infested by 

 this insect. 



The trees are all of them attacked at the extreme base, and the 

 exuding pitch flows out from the tree not infrequently a distance of 

 10 or 12 inches upon the humus which covers the ground. 



THE WORK OF THE LARVA. 



The larva begins its mine in a crevice in the bark, where the egg 

 was deposited, proceeding through the outer layers until it reaches 

 the cambium. Close to the wood it begins to construct a transverse 



Pig. 2. — Lodgepole pine trees infested by the sequoia pitch moth. Trees of all sizes are infested in the 



Clearwater country of Montana. 



mine running in both directions from where it entered. It widens 

 this tunnel at the center, thereby causing the appearance of a cen- 

 tral chamber. In small trees the mine is always practically straight 

 across the grain of the wood. 



It is a puzzle to the writer how the larva determines how far it 

 can go in the two directions without entirely girdling the tree, thus 

 killing it and thereby depriving itself of sustenance. It is a note- 

 worthy fact that of the great many trees less than 3 inches in diameter 

 examined, all were found girdled to within 1 or 2 inches, and none 

 entirely girdled. 



