24 THE CANADIAN ENTOMOLOGIST 



These conditions are frequently the cause of outbreaks of one or more species, 

 "which may be local (sporadic) or more general (epidemic) according to the nature 

 of the species of beetle involved in the attack. At the present time outbreaks 

 of a serious character are still in progress in certain parts of British Columbia, 

 caused by two species of Dendroctonus, the Western Pine Bark-beetle {D. 

 hrevicomis Lee.) and the Western White Pine Bark-beetle {D. monticolcB Hopk.). 

 Both of these species are destroying yellow pine in Southern British Columbia, 

 while the latter species is also attacking western white pine and lodgepole pine. 



Various other conditions favouring bark-beetle outbreaks also described in 

 this section, followed by an account of the natural factors and artificial methods 

 of control. 



The greater part of the bulletin, constituting Section III and IV is devoted 

 to the taxonomy and systematic treatment of the species. The external struc- 

 tures, in so far as they are of value in the determination of genera and species, 

 are described in detail, but the internal characters are omitted, as they are 

 useful only to the expert. 



The bark-beetles constitute the superfamily Ipoidea (Scoly toidea) , all the 

 Canadian species except one {Platypus wilsoni Sw., fam. Platypqdidse) belong- 

 ing to the family Ipida\ Keys . for the separation of the families, sub- 

 families, genera and species are given, and not only all the Canadian species 

 but also the majority of those found in the Northern United States are included, 

 as many of the latter may eventually be discovered in Canada. 



In the detailed account of the species, descriptive notes or full descriptions 

 are given when necessary, with the names of the host tree and a brief statement 

 of the geographical distribution. Ten new species are described, and 135 

 species are definitely recorded from Canada. 



The illustrations are beyond criticism. There are 31 plates, the great 

 majority being heliotype reproductions of photographs and drawings by Mr. A. E. 

 Kellett. The drawings are second to none we have ever seen, and the beauty 

 of their general appearance is in no way marred by the extraordinary minute- 

 ness with every detail is rendered. The photographs, showing the tunnels in 

 the bark and wood and other features of the work of the beetles and their larvie 

 are likewise extremely fine. 



Altogether this remarkable work deserves very speciid praise. It is one 

 of the finest contributions to Canadian entomology that has ever been pub- 

 lished, and great credit is due to the author, the artist and the Dominion 

 Entomological Service. 



Mailed January 28 th, 1919. 



