418 



WEST VIRGINIA EXPERIMENT STATION. 



they proceed in a body to feed on the bark before them, Fig. 

 LXXV1I, and ultimately eat out a great cavity as shown in the 

 same figure. 



This social brood chamber is often extended down towards or 

 even into the bark of the roots in such a manner as to hold the 

 turpentine flowing into it. Thus the larvae are often complete- 

 ly submerged in the viscid sub- 

 stance, which does not appear to in- 

 terfere with their progress. 



The first egg depositing period ex- 

 tends through the month of May. 

 Larvae are found in abundance from 

 the first of June to the beginning of 

 winter, fupae commence to ap- 

 pear early in July and may be found 

 from time to time until winter. It 

 appears that adults of the first brood 

 develop about the middle of July 

 and emerge in August or possibly 

 late in July, since 1 have found 

 young larvae by August 10th. Late 

 in the fall all stages are found in the 

 bark of infested trees, and often oc- 

 cur at this time under the bark of 



the roots as much as six inches 

 below the surface of the ground. 

 The winter appears to be passed 

 in all stages. 



Number of broods. The account 

 of this insect by Dr. Harris 1 would 

 indicate that there is but one an. 

 nual brood in the north, my ob- 

 servations lead me to conclude 

 that there is at least two broods in 

 the upper Austral zone in West 



Fig. LXXVI-.-Primary gallery of 

 Dendroctonus terebrans. 



Fig. LXXVII Larval mines of 

 Dendroctonus terebrans. 



I Ins. Inj. to Veg. p. 85. 



