24 SOME INSECTS INJURIOUS TO FORESTS. 



It would appear that the length of time spent in the larval state is 

 from 31 to 35 days. Sometimes, however, a few individuals of this 

 first generation, either from retarded development or other causes, 

 do not go through their transformations with the rest of the broods, 

 but remain as larvae all through the fall and winter, evidently chang- 

 ing to pupa? in the following spring. 



The length of time spent in the pupal stage is approximately 15 

 days. Pupae of this generation were observed in different broods 

 from August 14 to September 6. 



The first adults, evidently of this generation, were observed in the 

 bark August 14. The length of time spent in the bark after reaching 

 this stage appears to be from 7 to 14 days. It is difficult to tell just 

 when the emergences cease, as the last individuals of the brood come 

 out scatteringly. Thus, on October 10 a few adults were still found 

 in the bark. As this was the last observation, it is not known whether 

 adults emerged later in the fall or whether they passed the winter in 

 the bark before emerging; but the latter was probably the case. In 

 one tree under observation eggs were deposited July 6 and the broods 

 developed and emerged by August 28, a period of 53 days. Thus it 

 appears (1) that the first generation begins with eggs deposited 

 probably in the latter part of June; (2) that the majority of the 

 broods develop and emerge by the first part of September (a period 

 of about 60 days), but that some may continue to develop and emerge 

 until in October; and (3) that possibly some pupae and young and 

 matured adults may hibernate along w T ith the larvae. Thus it may 

 require 300 to 390 days or more for the complete development and 

 emergence of some individuals of the first generation. 



SECOND GENERATION. 



Eggs deposited by adults of what appears to have been the first 

 generation were found August 26 and as late as September 13. It 

 will therefore be seen that there is a partial overlapping of the periods 

 of the two generations. 



Larvae were found as early as September 4, and on October 10, 

 when the last observation was made, some larvae were apparently 

 full grown. 



No pupae or adults of this generation were found up to the time of 

 the writer's last observations— -on October 10, 1905. Mr. Burke 

 found adults, but probably of the first generation, excavating galleries 

 and depositing eggs as late as October 26, 1904. Thus it appears that 

 the second generation, beginning with the first eggs deposited by adults 

 of the first generation, passes the winter in the larval stage and develops 

 and emerges by the middle of the following June to the first part of 

 July.- It therefore occupies a period of about 315 to 330 days, includ- 

 ing about 60 days of activity in the fall, 165 days of hibernation, and 

 90 to 105 days of activity in the spring and early summer. 



