THE GENUS DENDROCTONUS. 
91 
SEASONAL HISTORY. 
OVERWINTERING STAGES. 
The winter is passed in the inner bark on trees attacked the 
preceding summer and fall, as parent adults in the egg galleries, all 
stages of larvae in the larval mines and transformation cells, and as 
broods of young adults in transformation cells; but principally 
as larvae. 
ACTIVITY OF OVERWINTERED BROODS. 
As soon as warm weather begins in April and May the over- 
wintered parent adults extend their incompleted egg galleries and 
Fig. 51. — The Black Hills beetle {Dcndroctonus ponderosx): a, Adult; 6, larva; c, pupa, a, Greatly 
enlarged; b, c, less enlarged. (Author's illustrations.) 
excavate new ones in the remaining living bark on the dying trees 
and deposit eggs. The overwintered broods of young adults begin 
to emerge from the trees by the middle of July, but the main swarm 
does not appear until the last of July and first of August. Some of 
the retarded broods continue to come out until October, or later. 
The broods of larvae begin to transform to pupae and adults about 
the middle of May, and continue to do so during the period from 
June until September, or later, and begin to emerge in August. 
