History and Habits of Pityogenes. li § 
provided the moisture conditions are suitable. They also 
quite commonly attack the trunks of weak or sickly young 
pines (especially in plantations) where the diameter is 
from one to three inches and the bark is still thin. 
A considerable amount of time was spent in observing the 
behavior of the insects when starting their new burrows. 
Most of these observations were made in the laboratory 
upon specimens removed from their hibernating burrows and 
placed in a closed jar with fresh limbs. Limbs were brought 
into the laboratory at 11:00 a. Mm. on March 13, 1915 from 
temperature of about 20 to 22 degrees Fhr. The bark was 
immediately stripped from a number of limbs and _ the 
young adults of both sexes removed from their hibernating 
burrows. Although the burrows contained frost and frozen 
frass the specimens showed evidence of life by weak move- 
ment of their legs. Within ten minutes many had righted 
themselves and were creeping about. They were left in 
covered watch glasses till 2:00 p. m. at which time most of 
them had regained entirely their normal activity. When 
these were placed upon limbs of white pine freshly cut 
from the tree and confined in glass jars, they immediately 
began creeping all over the pieces of limb, carefully examin- 
ing all of the crevices and roughened places on the bark. 
At 4:15 one specimen,:a male, was observed burrowing 
into the bark with its head and about one-fourth of its 
prothorax covered. Another one, a female, was examining 
the bark near and two minutes later had elevated her body 
nearly at right angles to the bark as if about to begin a 
burrow. She, however, was apparently only testing it as 
she abandoned work in less than a minute leaving no dis- 
cernible scar. The female continued scouting about in 
the near vicinity of where the male was working examining 
the bark carefully and poking her head into all the crevices. 
The piece of pine limb was now placed upon the stage of a 
binocular microscope and observations were continued with 
the 32 objectives and No. 4 oculars, using the light from two 
tungston bulbs. The male was undisturbed and continued 
to work steadily and apparently with some effort, push- 
