THE WESTERN PINE-DESTROYING BARKBEETLE. 23 



in the living inner bark, two adults to a gallery. Eggs occurred 

 singly in niches on the sides. 



He estimated that as a result of the work by this insect near Smiths 

 Ferry 30 per cent of standing timber was dead and 5 per cent was 

 dying. This was at the worst point of infestation, but scattered dying 

 timber was found all over Boise and Payette basins. The same con- 

 dition extended into the Bitter Root Forest Reserve. 



OBSERVATIONS BY THE WBITEK, 1905. 



The investigations by the writer during the summer of 1905, so far 

 as they related to this species, were mainly for the purpose of deter- 

 mining the principal facts in its life history and habits in the vicinity 

 of Centerville and Smiths Ferry, Idaho. The results may be sum- 

 marized as follows : 



LIFE HISTORY AND HABITS OF THE INSECT. 

 HIBERNATION. 



While it is probable, as observed by Hopkins at Grants Pass, 

 Oregon, that a few parent adults which enter the bark in the fall may 

 pass the winter in that stage, it appears that it is in the young to 

 matured larval stages that the insect normally passes the winter, each 

 individual in a separate mine or cell in the outer corky bark of the 

 tree in which it developed the previous summer and fall. The ear- 

 liest observations at Centerville were made on May 18, when larvae, 

 pupse, and young adults were found. Some of the larvae were small, 

 but the majority of them were mature and ready to change to pupae. 

 The pupse and adults had evidently transformed from larvae since the 

 beginning of activity in the spring. 



The latest date on which larvae of the hibernating broods were 

 found was June 13. Pupae were found as late as July 3, and adults 

 July 7. It is therefore evident that the majority of the over-wintering 

 broods develop to the adult stage by about the middle of June, but 

 broods from eggs deposited late in the fall may not develop until 

 nearly the middle of August. Adults begin to emerge in the latter 

 part of May and continue to do so through June and July and into 

 August. Thus the period of activity of the hibernating broods at 

 Centerville is probably from the first warm days in April and May 

 imtil about the last of July — approximately 90 days — the majority, 

 however, coming out in Jvme and in early July. 



PIEST GENERATION. 



The first generation at Centerville begins with the first eggs depos- 

 ited, apparently about the lastof June, by the adults developed from 

 hibernating larvae and pupae. These eggs hatch in about 4 days after 

 deposition. The principal egg-laying period for this generation is 

 evidently between the latter part of June and the first part of August. 



