THE GENUS DENDROCTONUS. 147 



, broad, convex; epistomal process and elytral rugosities variable 

 within the same species. 



Sexes. Females with front of head moderately broad; mandibles 

 'shining, moderately stout; antenna! club broad and stout; elytral 

 declivity slightly more rugose ; striae impressed with distinct punc- 

 tures. 



Males with front of head distinctly broader; mandibles opaque, 

 stout; antennal club narrow, more elongate, and the elytral declivity 

 slightly less rugose; striae less distinctly impressed, and the punctures 

 more obscure. 



Pupa. Vertex of head convex; front and middle femur each with 

 a minute subapical spine; abdominal tergites with moderately dis- 

 tinct spines. 



Larva. Abdominal tergites 8 and 9 with distinct dorsal plates, 

 each armed with three prominent teeth. 



Galleries. Egg galleries slightly winding to nearly straight; larval 

 mines not separated, except very rarely near the outer extremity, 

 but forming broad common larval chambers. 



22. Dendroctonus terebrans (Olivier). 



(PI. VII, fig. 22.) 



Adult. Typical female: Length 5.6 mm., black. Front convex, 

 without impressions; epistomal process moderately broad, lateral 

 angles tuberculate. Pronotal punctures very coarse, regular, mod- 

 erately dense, scarcely decreasing in size toward base; elytra with- 

 out long hairs toward base. 



Typical female labeled, name label, "Hopk. 1/22/08, Pinus echi- 

 nata, Hopkins, collector, Tryon, N.C., 9 , Hopk. U. S. 530aa." 



Typical male: Length 5.6 mm. Differs from female in stouter 

 mandibles and slightly coarser rugosities of elytral declivity. 



Typical male labeled same as female. 



Variations. The length varies from 5 to 8 mm., with the average 

 about 7 mm. The color ranges from piceous to deep black, the latter 

 prevailing. Immature specimens are reddish, but fully matured 

 ones are always darker than the darkest D. valens. The greatest 

 variation is in size, and while the usual variation prevails in some of 

 the other characters, it is much less so than in D. valens. In New 

 Jersey, Pennsylvania, Virginia, and West Virginia, where there is an 

 overlapping of the range of D. valens and D. terebrans, specimens are 

 sometimes found which appear to be hybrids, but it appears that the 

 more dominant characters of D. terebrans prevail in such hybrids, so 

 that the darker color and coarse punctures of the pronotum serve to 

 distinguish them as being more closely allied to the latter species. 



Distinctive characters. The characters which serve to distinguish 

 this species from D. valens, to which it is more closely allied, are its 



