154 



THE SCOLYTID BEETLES. 



punctured, becoming finer toward base, the sides slightly narrowed 

 toward the head, but not strongly constricted; the elytra with coarse, 

 transverse to oblique rugosities between distinct to obscure rows of 

 punctures; the declivity convex, with moderately deep grooves, and 

 the intervening spaces slightly convex and roughened; the entire 

 body sparsely clothed with long hairs. (See fig. 97.) 



It attacks the living bark on injured, dying, healthy, and felled pine 

 and spruce in eastern United States and Canada, north from the 



mountains of North Car- 

 olina, westward to the 

 Pacific coast, and south- 

 ward from British Co- 

 lumbia into Mexico. The 

 parent beetles excavate 

 broad, somewhat irregu- 

 lar, winding, longitudi- 

 nal egg galleries (fig. 98) 

 through the inner bark 

 and groove the surface 

 of the wood. The eggs 

 are placed in groups or 

 masses at intervals along 

 the sides of the galleries. 

 The stout, yellowish- 

 white, cylindrical larvae, 

 with reddish heads and * 

 stout spines on the dorsal 

 plates of the last ab- 

 dominal segments, do 

 not make separate larval 

 mines, but all feed to- 

 gether and eat out cavi- 

 ties in the inner bark from 

 a few inches square to 

 several feet square (see 

 fig. 98) . They transform 

 to pupsB and adults in 

 separate or closely joined cells in the inner bark, or inner' portion 

 of the outer bark, or in mines extending from the social cham- 

 ber. The broods work independently of other ^ecies and occupy 

 and separate the bark around the base of tre^r and stumps (see 

 fig. 99), often extending their work for a foot or more onto the 

 roots beneath the surface, and the broad larval chambers are often 

 filled with semiliquid resin., without injury to the occupants. Tt© 



Fig. 97.— The red turpentine beetle (Dendroctonue valema): 

 Adult. Greatly enlarged. (Author'sillnstration.) (Seealso 

 fig. 4, larva; fig. 6, pupa.) 



