12 



Canadian Forestry Journal, January, 1919 



COMBATTING INSECT FOES OF THE FOREST. 



Fires, insects and parasitic fungi are the 

 most d?structive enemies of our forests. Each 

 season fresh forest areas are swept by fires or 

 devastated by outbreaks of injurious msects and 

 fungi. The extensive balsam injury in Eastern 

 Canada illustrates the serious nature of these 

 insects and fungus enemies. The primary injury 

 was caused by the Spruce Budworm, and in 

 Quebec Province, although the Budworm out- 

 break has passed by, thousands of balsams have 

 died from the primary defoliation and great 

 numbers of the weakened trees are dymg now 

 from attacks of more recent enemies, notably 

 the Eastern Balsam Bark-beetle, the Balsam 

 Bark Weevil, and a very destructive sapwood 

 fungus. 



The insect enemies of Canadian Forests are 

 being studied by the Entomological Branch of 

 the Dominion Department of Agriculture. A 

 bulletin dealing with Canadian Bark-beetles has 

 been issued recently by the Forest Insect Divi- 

 sion of the Entomological Branch, written by 

 Mr. J. M. Swaine, Parts I and 2 have been pub- 

 lished thus far. Part 1 , "Descriptions of New 

 Species," describes 40 new species of Bark- 

 beetles from Canada and the Northern United 

 States. Part 2 gives "A Preliminary Classifica- 

 tion with an account of the Habits and Means 

 of Control." In the First section of the 2nd 

 part, the beetles and their habits are described, 

 with a detailed account of the interesting and 

 sometimes beautiful system of tunnels cut by the 

 adults and their larvae. The Second section 

 deals with Bark-beetle injuries and the means 

 of control. Bark-beeltes are probably our most 

 destructive forest insects. They are very small, 

 dark beetles, varying from one to nine milli- 

 metres in length. Both adults and larvae exca- 

 vate tunnels in the inner bark of trunks and 

 branches of many of our timber trees. When 

 green timber is attacked the multitude of small 

 tunnels girdles the trunk in hundreds of places 

 and the tree usually dies in less than a year from 

 the time of attack. Their most extensive injuries 

 to our forest in recent years have been caused 

 in British Columbia, but they are everywhere 

 destructive throughout the eastern woods. The 

 injury to eastern balsam by the Eastern Balsam 

 Bark-beetle at the present time is a good ex- 

 ample. In addition to many "primary" species, 

 which attack and kill green timber, many "sec- 

 ondary" species are always found in weakened 

 and dying trees. These secondary enemies 



assist the more destructive species in killing 

 trees, following up the original attack, but are 

 often found initiating outbreaks in green timber 

 on their own account. 



Value of Slash Burning. 



The Control Measures discussed in this chap- 

 ter include the destruction of the broods of 

 beetles during winter by modified logging opera- 

 tions, and properly conducted slash-burning. 

 With the destructive species the winter is passed 

 by the beetles and their small whitish larvae or 

 grubs under or in the bark of the trees attacked 

 by them that summer, and in the green slash 

 and stumps. If infested trunks are removed 

 and treated, by driving for instance, so that the 

 broods in the bark are killed before June, and 

 if, in addition, the slash is burned, the number 

 of the destructive species may be so reduced 

 that satisfactory control is effected in one season. 

 Slash-burning is strongly recommended as an 

 effective method of insect and fungus control. 



The Third section gives a short account of 

 the structural characters of bark-beetles, suffi- 

 cient to explain the technical terms employed in 

 the keys for determination in the section which 

 follows. 



The Fourth Section, comprising about 100 

 pages, presents an arrangement of the Canadian 

 Bark-beetles with keys for determination, so that 

 students and foresters with a little training in 

 the use of keys of this kind may be able to 

 determine the species of bark-beetles for them- 

 selves. 



Accuracy Essential. 



The control measures depend entirely upon 

 the habits of the beetles, and the habits vary 

 with the species. It is therefore necessary to 

 determine exactly which species is causing the 

 primary injury. There may be a dozen species 

 of bark-beetles in the bark of a group of dying 

 spruce, but only one or two of them will be 

 concerned in the primary attack on the green 

 timber. 



The bulletin is fully illustrated with 31 full 

 page plates, twenty-seven of these by the helio- 

 type process, and five text figures, over 265 

 figures in all. It is distributed free in Canada 

 to those interested in forest protection, and may 

 be obtained through the Dominion Entomologist, 

 Entomological Branch, Department of Agricul- 

 ture, Ottawa. 



