Canadian Bark-beetles. 



PART II. A PRELIMINARY CLASSIFICATION, WITH AN ACCOUNT 

 OF THE HABITS, INJURIES AND MEANS OF CONTROL. 



BY J. M. SWAINE 



INTRODUCTION. 



This bulletin has been written with the object of assisting students and 

 practical foresters in determining the bark-beetles of Canadian forests. The 

 majority of the species occurring in the northern regions of the United States 

 have also been included, since nearly all may eventually be. found in Canada. 



The bark-beetles of this country have thus far received but little attention 

 from most collectors and students of the Coleoptera. There were until recently 

 so many common species undescribed, and the older descriptions were so incom- 

 plete, that their determination was frequently given up as a hopeless task. 

 Furthermore, while many of the species may be obtained in quantity, when 

 the collector knows their habits, most of the bark-beetles are taken only in the 

 bark or wood of their host trees, and then only by those who seek them. Owing 

 probably to these two causes our literature shows a lamentable dearth of biolo- 

 gical papers on North American bark-beetles. While the life-histories and 

 habits of the European species have been discussed in scores of papers, the habits 

 of very few of ours have been published, excepting the species of the genus 

 Dendroctonus. 



There are still numbers of our species undescribed. Some have been 

 received or collected since these keys were finally revised. Others are repre- 

 sented in our collection by one or two specimens, and may prove to be only 

 marked variations, and there are many other species, undoubtedly, that have 

 not yet been collected. 



The study of a group of beetles containing so many destructive enemies of 

 forests and shade trees is of particular importance. Careful and detailed 

 studies of the structural characters and habits must be made so that the injurious 

 species may be readily determined and practical remedies perfected. A single 

 dying pine or spruce may contain many species of bark-beetles working in the 

 bark and wood. The entomologist must be able to determine all the different 

 species he meets and must have a working knowledge of the habits of all of 

 them so that, with the assistance of the evidence before him in the trees them- 

 selves, he may be able to select the species responsible for the primary injury 

 to the timber. It is evident, therefore, that intensive laboratory studies upon 

 the morphology and classification of the beetles are absolutely necessary, and 

 that time spent upon even the species of apparently minor economic importance 

 may give decidedly practical results. 



Mr. A. E. Kellett, Artist Assistant in the Entomological Branch, has 

 drawn the illustrations which bear his signature, under the supervision of the 

 writer, and has prepared many of the photographs. The writer is indebted to 

 many students of the Coleoptera and to several institutions for the privilege of 

 studying their collections. This assistance will be acknowledged more fully in 

 later publications dealing with the biology of the species. 



7 



