THE CANADIAN ENTOMOLOGIST 23 



RECENT CANADIAN PUBLICATIONS. 



(Continued from Vol. L, p. 427). 

 Canadian Bark-beetles. Part II — A Preliminary Classification With 



AN Account of the Habits, Injuries and Means of Control. By 



J. M. Swaine. Bulletin No. 14 (Technical Bulletin) Dept. of Agriculture, 



Entomological Branch, Ottawa. Issued Sept. 6, 1918. 143 pp. 31 pis. 



It is only within comparatively recent years that the importance of the 

 Bark-beetles as enemies of North American forests has been fully appreciated 

 even by the forest entomologist. Every year the necessity of stricter economy 

 in the conservation and utilization of our forests becomes more urgent, and it is, 

 therefore, fortunate that we have in Canada so able an authority as Mr. Swaine 

 as a source of information, both practical and scientific, on this group of depre- 

 dators. 



The first part of this bulletin, which was published in 1917, contains 

 descriptions of a large number of new species of bark-beetles. The second part 

 treats of their habits", bionomics and classification, as stated in the title, and 

 has been prepared with the object of enabling students and practical foresters 

 to identify the Canadian species of this group of insects. It is divided into four 

 sections, the first entitled "The Beetles and their Habits;" the second, "Bark- 

 beetle Injuries and the Means of Control;" the third, "Structural Characters of 

 the Bark-beetles," and the fourth, "Classification. A Preliminary Arrangement 

 of the Canadian Bark-beetles." 



Section 1 is an admirable account of the general life-history of these insects, 

 based upon an intimate first-hand knowledge of a great variety of species. 

 The different types of egg tunnels, larval mines, methods of oviposition, and other 

 details of their habits are described with conciseness and precision. Among 

 other interesting features in this section are the statements that the so-called 

 ventilation tunnels are used mainly as turning-niches by the females during 

 oviposition and as storage places for boring dust and that the nuptial chambers 

 are used by some species for the same purposes. 



In Section II the species of bark-beetles are grouped under three headings, 

 primary enemies, secondary enemies and neutral species. Primary enemies are 

 those species which commonly attack and kill healthy trees, the most important 

 of these being certain large forms belonging to the genus Dendroctonus. Second- 

 ary enemies are thovse species which habitually Ijreed in the bark of dying trees 

 and logs, but these are frequently injurious in that they kill weakened trees 

 which might otherwise recover. Secondary enemies may become of primary 

 importance under conditions favourable for their rapid reproduction, as in the 

 case of various species of Ips. All of the Canadian species under normal con- 

 ditions seem to prefer to breed in dying or weakened trees. Some of the twig- 

 boring species may be abundant enough to cause some injury, while others may 

 be actually beneficial by hastening the death of the lower branches of pines and 

 spruces, thus helping to produce cleaner trunks. The neutral species are of no 

 economic importance as they breed only in dying or dead bark. 



Attention is called to the effect which neglected slashings produce in in- 

 creasing the number of scattered dying trees in the vicinity on account of the 

 favourable conditions thus brought about for the breeding of bark-beetles. 



January, 1919 



