THE GENUS DENDROCTONUS. 59 



SECOND GENERATION. 



The first eggs of the second generation are deposited by adults of 

 the first generation during the first week of July. The principal 

 attack, however, is during the latter part of July and first of August. 

 The larvae of this generation begin to hatch about the middle of 

 July, continue to hatch during the latter part of July and early part 

 of August, begin transforming to pupae and adults during the first 

 half of August, and continue to do so into September or later. The 

 broods of adults begin to emerge about the 10th of August and con- 

 tinue to come out during the middle to last of the month, and until 

 the last of the retarded broods have left the trees, in September or 

 later; but practically all of the normally developed broods are 

 evidently out by the middle of September. 



THIRD GENERATION. 



The adults of the second generation evidently begin to attack the 

 trees and deposit eggs for the third generation about the middle of 

 August, and continue to do so into September or later, though the 

 principal attack is during the last half of August. The larvae begin 

 to hatch in a few days after the eggs are deposited, and develop 

 principally during the last of August and first half of September, 

 but some of them do not complete their development before hiber- 

 nation begins in the fall. The matured larvae transform to pupae 

 and adults principally during September, but continue their trans- 

 formations into November or later. The developed broods begin to 

 emerge about the middle of September, and probably continue to 

 come out until November or later. The majority, however, evidently 

 emerge before the middle of October. 



FOURTH GENERATION. 



The adults of the third generation evidently begin to attack the 

 trees and deposit eggs about the middle of September, and continue 

 to do so during the latter part of September and first of October, 

 until cold weather. The principal development of the larvae is dur- 

 ing October, practically all becoming full grown before hibernation 

 begins, so that the majority pass the winter as full-grown larvae in the 

 outer bark. Some of the earliest broods evidently begin transform- 

 ing to pupae and adults toward the middle of October, and some of 

 them may emerge in October and November, but evidently by far 

 the larger number of both the young adults and the developed larvae 

 pass the winter in the outer bark. 



