THE SEQUOIA PITCH MOTH. 3 



behind, those given here. The flight and oviposition of the insect are 

 over by August 1. 



It appears that the adult insect is rather short-lived, as all the 

 specimens that were reared and observed in captivity died within four 

 days of emergence. Out of 20 females thus under observation only 

 one oviposited, the rest dying without issue. This would show that 

 the female dies, unless she is fertilized, within three days after 

 emergence. 



As this species is very active it is reasonable to suppose that it 

 deposits but few eggs in any one place. In fact, it was frequently 

 observed that wherever two larva? are too close together one of them 

 invariably dies. Wherever an occasional pitch mass is found to 

 contain as many as three larvae, each one of them occupies an inde- 

 pendent tube. This shows that the scattering of the eggs is neces- 

 sary in order to enable most larvae to survive the evidently fierce 

 struggle for existence. Exactly how long it takes the eggs to hatch 

 is unknown to the writer, but the injury to the newly infested trees 

 by the young larvae is quite perceptible by August 15. By the time 

 frost arrests their activity, about October 1, the larvae, especially 

 the females, have attained considerable size. The following summer 

 is demoted by the larva to lengthening the tunnel and growing, and 

 toward the second winter it drives a rather roomy tunnel into the 

 pitch exudation which, during the following June, it lines with silky 

 thread preparatory to pupation. 



During the two months preceding pupation all the larvae of the 

 same sex are of practically the same size, so that the two generations 

 are almost inseparable. However, one familiar with this and allied 

 species can separate them by the difference in color and density of 

 skin, which is rather white in the younger generation and yellowish, 

 leathery, in the older one. 



The length of the pupal stage is 30 days, i. e., the insect remains 

 in the chrysalis for 30 days from the day it transforms into that 

 stage until it emerges as adult. The chrysalis is free in the tunnel, 

 moving back and forth in it at will by means of spines on the body, 

 and is usually found on warm days quite near the surface and far 

 back when it is cold. When ready to emerge the pupa forces about 

 half its length out through the thin shell of pitch at the mouth of the 

 tunnel and the adult insect (fig. 1) emerges by bursting the shell of 

 the chrysalis. This occurs two years after the egg was laid. In 

 other words, the larvae hatching from the eggs deposited in June and 

 July of one year develop into adults during the same months two 

 years later, thus making the generation biennial. 



There seems to be indication of an alternation of seasons of abun- 

 dance and scarcity of the insect. During late autumn, 1913, the 

 young larvae were quite scarce in the vicinity of Rainy Lake, espe- 

 cially east of the wagon road from Clearwater to Swan River, while 



