DOUGLAS FIE PITCH MOTH. 



proves that it is fairly numerous, it is only by good fortune that one 

 gets a chance to observe its behavior. During two seasons of 

 judiciously chosen days and locations for observations the writer 

 saw but six specimens in the forest. They were all females, and 

 each of them was apparently engaged in oviposition. "While the 

 insect swiftly wings its way up and down the tree trunk, the eggs 

 are deposited, either at the edge of a wound or a perfectly smooth 

 spot, oftener the latter, and only a single egg is deposited at each 

 place. 



In Montana, where the insect is not exceedingly numerous, the 

 writer and Entomological Rangers Swartz. Wagner, and Fleming- 

 examined hundreds of trees, each of which displayed comparatively 

 fresh, healed-over wounds, un- 

 questionably of sesiid origin, but 

 in no case was more than one 

 larva of each of the triennial gen- 

 erations found at the same time in 

 the same tree. This suggests that 

 if there is an abundance of suit- 

 able trees for infestation a female, 

 after depositing one egg only on a 

 tree, leaves the latter, repeating 

 the same operation until its sup- 

 ply of eggs is exhausted. Conse- 

 quently quite a number of trees are 

 thus affected by a single female. 



From Ashland. Oreg., where 

 the insect is much more abundant 

 than in the Rocky Mountains, Mr. 

 Edmonston reported as many as 6 larva?, all of which proved to be 

 of the same generation, from a single tree, and Mr. B. T. Harvey 

 .states that quite a number of trees in the coastal region are scarred 

 from base to near the tops by the work of this moth. 



I have no doubt that this apparent discrepancy in ovipositing is 

 due solely to the fact that in regions where the insect is nearly ten 

 tiiiic- as numerous as in the Rocky Mountains several females by 

 chance deposit eggs upon the same tree; in fact, they are compelled 

 to do so. unless they are willing to oviposit on trees that are unde- 

 sirable on account of growth. 



By August 1 young larva- from the June oviposition, upon close ex- 

 amination of the infested tree-,, may be readily located by the boring 



dust. Which resemble- that of I ><n<i 'rorf Onus pseud ' of siKJiic Ilopk. 



This dust i- produced by the Larva eating its way through the outer 

 bark into the cambium. At the end of the first active season a pitch 



tube covers the wound as well as the larva which made it. 



Fig. 1. — Three generations of larvse of 

 the Douglas fir pitch moth (Kesia nova- 

 roensis). Natural size. (Original.) 



