62 



FF The punctures of the discal striae of the elytra usually- 

 coarse. 



G The average size smaller, 5-5 mm.; the elytral striae 

 somewhat more commonly strongly im pressed on the 

 sides. East of the Great Lakes, in Eastern Spruce. 



piceaperda Hopk. Page 66. 



GG The average size larger, 6-5 mm.; the elytral striae 

 more commonly faintly impressed upon the sides. 

 The northern Pacific coast in Sitka Spruce. 



obesus Mannh. Page 66. 



Dendroctonus brevicomis Lee; Am. Phil. Soc. Proc, 15: 384, 386, 1876. 



Length, 3-2 mm. to 5 mm., average 4-2 mm.; colour dark brown to 

 black; the front elevated on each side of a deep median groove in the male, 

 faintly so in the female; sides of the epistomal process oblique; the pronotum 

 shining, hardly constricted in front, feebly so in the male ; the elytra as wide 

 as the pronotum; the striae faintly impressed, the strial punctures very 

 small, the discal interspaces densely, finely asperate, the declivital striae 

 faint; broadly impressed on each side of the elevated suture; the pubescence 

 rather abundant, everywhere short, erect, and inconspicuous, with a few slightly 

 longer hairs intermixed on the declivity. The female has a narrow, trans- 

 verse elevation across the pronotum behind the cephalic margin, continued 

 across the sides; the male has a transverse depression similarly situated. 

 (PI. 12, fig. 5). 



The egg-tunnels are winding, more or less transversely, the egg-niches 

 separated, the larval mines in the inner and middle layers of bark. 



Host tree, in British Columbia. — Western Yellow Pine. 



Distribution.— Thronghont the range of yellow pine in British Columbia 

 and in the Western States. 



Economic importance. — This species assists monticoloe in extensive out- 

 breaks in southern British Columbia. 



D. barberi Hopk. (Arizona, North Mexico, Texas, Colorado, Utah), is 

 described as distinct through coarser rugosities of the elytral interspaces 

 and more distinctly impressed elytral striae. 



Dendroctonus pseudotsugae Hopk.; Bur. Ent. U.S. Dept. of Agric, Tech. 

 ser, 17, pt. 1, The Genus Dendroctonus, p. 126, 1909. 



Length, 3-5 mm. to 7 mm., average nearly 6 mm.; the colour dark 

 brown to nearly black, and black with the elytra red; the epistomal process 

 with the sides parallel and with its anterior margin usually projecting 

 slightly beyond the margin of the epistoma; the pronotum shining, finely, 

 closely punctured, with few larger punctures intermixed. Very closely 

 allied to simplex Lee, but entirely distinct (PI. 12, fig. 2). 



Host trees. — Douglas Fir and Western Larch in British Columbia, and 

 in United States, Big Cone Spruce, in addition. 



Distribution. — It follows the range of its host trees in British Columbia, 

 and apparently also in the United States. 



Economic imjjortance. — This species prefers djdng bark and is found 

 everywhere in British Columbia in slashings of its host trees. Small out- 

 breaks in living timber are found in British Columbia, but these are easily 

 controlled by proper disposal of slash. It may become an important 

 primary enemy. 



Dendroctonus simplex Lee; Am. Ent. Soc. Trans., 2: 173, 1868. 



Length, 3-5 mm. to 5-2 mm., the average about 4-7 mm.; the front 

 convex, densely, roughly punctured, with the median line finely impressed 



