136 Psyche [October 



here to deal not only with the slowing up of the life processes of the 

 insect in all of its stages, but also with a retarding influence which 

 the relatively lower temperature and higher humidity seems to 

 exert directly upon the young beetle, which prevents it from leav- 

 ing its old host. These conditions simulate partially and in a 

 milder way the climatic influences which in the fall prevent adults 

 from emerging, although they are fully matured and will leave their 

 old host in a few days if brought into the laboratory where they are 

 under fairly warm and stable temperature conditions. 



The brood burrows of P. cariniceps are constructed in small limbs 

 and twigs from 5 mm. to 16 mm. in diameter. They form rather 

 coarse engravings and are excavated nearly entirely from the sap- 

 wood (Plate VII, fig. 1). The direction of the egg-galleries de- 

 pends upon the diameter of the limb in which the insect works. 

 In the smaller twigs they are necessarily mainly longitudinal, 

 while in the larger material the direction is more likely to be diag- 

 onal. The nuptial chamber is rather large and very irregular, 

 often with several short feeding galleries leading from it — probably 

 made by the male — in addition to the true egg-galleries. The 

 egg-galleries in the material at hand, vary in number from one to 

 five to the engraving, with an average of three. They are wide and 

 deep and vary in length from 5^ mm. to 65 mm. the average being 

 about 24 mm. The egg-niches are irregularly arranged on each 

 side of the gallery and are excavated nearly entirely from the 

 wood, although the larvae at first feed chiefly upon the bark. In 

 the material studied the average number of niches in an egg- 

 gallery is about 10, but varies from 1 to 37 in the individual 

 galleries. 



The insects found most commonly associated with P. cariniceps 

 are P. nudus Sw., P. granulatus Sw., P. puberulus Lee, Pitogenes 

 hopkinsi Sw., and an undetermined Thripid. Of these P. pub- 

 erulus and P. nudus were associated only in the smaller twigs, 

 while Pityogenes hopkinsi occurred only in those more than 1 cm. 

 in diameter and here only rarely. 



Pityophthorus canadensis Swaine. 



Specimens of Pityophthorus canadensis Sw., which at the time 

 were believed to be P. cariniceps, were taken by the writer on 

 June 20, 1918, near Cranberry Lake in the Western Adirondack 



