THE GENUS DENDROCTONUS. 



83 



Variations. Length, 3 to 5 mm.; color light brow^nish to nearly 

 black; punctures of pronotum ranging from moderately coarse to 

 very fine, elytral striae not at all impressed in some examples, in 

 others the impression and punctures more distinct, but never as 

 distinct as in ttje majority of D. barberi. The elytral rugosities 

 also vary from very fine to moderately coarse. The front varies 

 greatly, from convex without tubercles to deeply grooved and with 

 prominent tubercles. The epistomal process varies from the nor- 

 mal concave form with angles elevated and lateral margins strongly 

 oblique to flat with rounded apex and lateral margin suboblique. 



.Distinctive characters. 

 The adults of this species 

 are at once distinguished 

 from its nearest ally, D. 

 barberi, by the finer rugo- 

 sities of the elytral inter- 

 spaces and the much less 

 distinctly impressed striae. 



Revisional notes. The - J.i 

 labeled type in the Le 

 Conte collection agrees 

 with the description, ex- 

 cept that the prothorax is 

 not nearly twice as broad 

 as long. It is certainly 

 distinct from D. frontalis. 

 The specimens in the Horn 

 collection under D. fron- 

 talis that evidently repre- 

 sent part of the material 

 on which Doctor Dietz 

 based his revision, include 



one specimen of D. frontalis labeled with red disk, one speci- 

 men of D. brevicomis labeled "Cal.," one specimen of D. barberi 

 labeled " Williams, Ariz. 7. 28," one specimen of D. arizonicus(T) 

 11 Williams, Ariz. 7. 28," and one specimen without locality label. 

 One specimen was also received from Dietz, under D. frontalis, 

 labeled " Arizona," which proved to be D. barberi. In 1898 D. brevi- 

 >s Lee. was not represented in the U. S. National Museum. There- 

 fore it appears that up to 1899 there were only two specimens of the 

 species in the large collections of the country. 



Pupa. In addition to the divisional and subdivisional characters, 

 the pupae range in length about the same as adults ; the apices of the 

 front and middle femora are smooth; abdominal tergites 3, 4, 5, and 







FIG. 45. Dendroctonus brevicomis: Bark showing, o, pupal 

 cells; 6, exit burrows; c, pitch tubes. (From Webb.) 



