OBSERVATIONS ON THE LIFE HISTORY AND 
HABITS OF PITYOGENES HOPKINSI SWAINE 
M. W. Briacxman, Px. D. 
(With Six Plates) 
The study of the life history and habits of the various 
members of the superfamily Scolytoidea offers as many points 
of interest either from the standpoint of pure science or from 
the economic aspect as does that of any other group of 
beetles. In spite of this, however, careful study of the 
biologies of this very interesting group of insects has been 
neglected in this country except in the case of a very few 
forms which are of great economic importance. Perhaps 
explanation of this neglect is to be found in the diftculties 
experienced in studying these insects consequent upon their 
very secluded life, as they remain either under the bark or 
within the wood of the host plant throughout their life, 
except for the short time required in finding a new host. 
However, by the exercise of a little ingenuity and of con- 
siderable patience, the main facts of their life histories and 
many of their interesting habits can be observed. This is 
especially true of those members of the group which 
habitually feed and breed in the thinner barked portions of 
cut trees, as the habits of these render them more easy of 
manipulation in the insectary and more amenable to obser- 
vation in the laboratory. 
Most of the observations here recorded were made upon 
insects in artificial cultures in the laboratory, supplemented 
wherever possible by observations in nature. In the labora- 
tory the conditions of moisture, ete., were kept as near as 
practicable to conditions which prevailed in the field and 
observations upon the length of the various stages of the life 
history have been checked up by similar data collected in the 
field. Detailed study of the habits of the insect in making 
its burrow and in guarding it and its behavior under various 
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