History and Habits of Pityogenes. 57 
In the breeding jars in the laboratory it was found that 
the beetles would readily feed upon hemlock (Pseuga cana- 
densis), red spruce (Picea rubens) balsam fir (Abzes bal- 
sameus and Austrian pine (Pius austriaca) even in the 
same jar with fresh white pine. They were able to main- 
tain themselves in any of these for a period of three weeks 
or more, but in none of these was any brood found, and in 
only one — the Austrian pine — did any of the males con- 
struct the characteristic beginning of the brood burrow — 
the nuptial chamber. 
Without a doubt the favorite host plant, both for feeding 
and for rearing the brood, is the eastern white pine. That 
several other species of pine in the northeastern United 
States and Eastern Canada also serve as host trees is also 
fairly certain, although the author has never had an oppor- 
tunity of ascertaining this at first hand. 
Economic Retarions.— Pityogenes hopkinsi attacks 
only thin barked pine, and its favorite breeding place is in 
the recently cut limbs of felled white pine. To such material 
it is attracted in countless numbers and it is therefore very 
numerous following lumbering operations. It seems to have 
a decided preference for recently killed and suddenly killed 
limbs, and next to its preference for pine “slash” it finds 
most favorable conditions in lightning-killed trees. It, how- 
ever, breeds very freely in limbs which are sickly or dying 
from other causes provided the bark upon these is not in too 
dry a condition. It will breed to a certain extent in limbs 
which are undergoing the process known as being “ shaded 
out.” However, very often limbs dying in this manner pos- 
sess a very tough, hard, dry bark which adheres closely to 
the wood, and if such is true the beetles cannot breed in it. 
They prefer to attack such limbs while still green and sappy 
and in so doing often hasten their death. From a forestry 
standpoint they serve in such cases a beneficial purpose in 
that they aid and hasten the natural pruning which is neces- 
sary for the production of clear timber. 
However, in other cases they are not beneficial in their 
effects. On a number of occasions they have been found at- 
