348 NEW YORK STATE MUSEUM 



down and four upwards. In the farther portions of the galleries are series 

 of expanding larval burrows. It will be seen that these are placed at 

 somewhat regular intervals and are due to the fact that the female gnaws 

 small chambers at these points and places an egg in each. Sometimes 

 eggs are deposited very largely on one side of the gallery and at others 

 on both sides. The larval galleries dilate gradually, with the growth of 

 the young, have a somewhat serpentine course and end in an oval pupal 

 cell. They form perfect mazes of interlacing burrows when at all abun- 



Fig. 6q Middle tibiae: a, ^=Dendroctonus terel>rans, the former from Karner, the latter from 

 Manor ; <r=T omicus calligraphus (original) 



dant because the galleries of the young of different females may interfere 

 more or less. It frequently happens that the beetles are so abundant as to 

 eat away a considerable proportion of the bark and plate 55, figure 3, shows 

 this condition very nicely and figure 1 on the same plate represents the 

 same thing in a more advanced stage. The condition of the trunk of the 

 tree after it has harbored large numbers of these borers is shown on plate 

 54, figure 1. It will be seen that all of the bark has dropped from the 

 trunk and that many very shallow grooves have been made in the surface 



