67 



these characters are hardly rehable; the elytral striae are usually faintly 

 impressed, especially on the sides. D. borealis Hopk. usually has the elytral 

 striae a little more evidently impressed, with the punctures of the discal 

 striae smaller and less easily distinguished. The variations in obesus from 

 the west coast, and in borealis from Alberta and the Rockies are so numerous 

 that many individuals could never be determined if the place and host 

 labels were removed. We have long series from the regions just named, but 

 have made no collections in the section between Jasper Park and the 

 Pacific Coast. When long series are available from that intervening region, 

 the status of borealis may be more definitely decided. At present I am 

 of the opinion that obesus, borealis and engelmanni form one variable species, 

 with piceaperda only doubtfully distinct. (PI. 12, fig. 6). 



Host tree. — Sitka Spruce. 



Distribution. — The Pacific Coast, from Alaska southwards into the 

 United States throughout the range of the host tree. 



Economic importance. — It evidently prefers dying bark under ordinary 

 conditions, but readily attacks trees of the largest size, at most but slightly 

 weakened, and is without doubt a destructive primary enemy when the 

 right conditions obtain. 



The Genus Phloeosinus Chapuis. 



Chapuis, Syn. Scol., p. 37, 1869. 



*Key to the Species. 



A The mesosternum precipitous, at least very steep, between the coxae; 

 the intercoxal piece of the prosternum usually wide; the antennal club 

 with the sutures subtransverse, only moderately oblique, (excepting 



punctatus.) 



B The mesosternum transversely, acutely carinate between the coxae; 

 the metasternum sparsely, feebly punctured; the declivital inter- 

 spaces similar, feebly convex, uniseriately granulate ; breeds in Pinus 

 banksiana. pini Sw. Page 69. 



BB The mesosternum not carinate; the metasternum usually coarsely 

 and roughly punctured. 



C The strial punctures very distinct and coarse on the disc, in deeply 

 impressed striae of moderate width; the 2nd interspace on the 

 declivity evidently narrower than the 1st and 3rd. 



D Very small species, the length, 2 mm. or less; the pubescence 

 distinct; the discal interspaces with coarse uniseriate asper- 

 ities in addition to the granules. 



E The declivity reddish, minutely scaly, with 1st and 3rd 

 interspaces strongly serrate and much more strongly 

 elevated than the 2nd. California. hoppingi Sw. 



EE The colour entirely black, declivital vestiture hairlike, 

 with 1st and 3rd interspaces feebly serrate and but little 

 more elevated than the 2nd. California, minutus Sw. 



DD Of medium size, the length, 2-2 mm. to 3 mm.; the pubescence 

 indistinct; the discal interspaces confusedly very coarsely 

 granulate; the striae wide and the punctures very coarse. 



punctatus Lee. Page 69. 



For serratus Lee. see page 70. 



36198—5^ 



