634 



Canadian Forestry Journal, July, ipi6. 



eastern Canada, New York and New 

 England, comparable to the bark 

 beetle outbreaks by nwnticolae and 

 hrevcouiis now raging in British 

 Columbia and the Western States. 

 In the several outbreaks billions of 

 feet of the finest Eastern Spruce 

 were killed and later largely de- 

 stroyed by fires. There have been 

 reports recently of small areas of 

 dying Spruce in the Quebec forests, 

 and these will be investigated this 

 summer. Any evidence of the 

 activity of this most destructive 

 enemy should receive immediate at- 

 tention. 



Slash Burning a Help. 



The Douglas Fir and Western 

 Larch are attacked and killed by the 

 Douglas Fir Bark Beetle, Dendroc- 

 toniis pseud otsiigae, everywhere 

 throughout its range in British Co- 

 lumlna. Isolated dying trees and 

 small clumps of red-tops indicate the 

 injury in many places. There are at 

 present extensive outbreaks by this 

 beetle in our forests, but the aggre- 

 gate loss from its attack on isolated 

 trees is great. Probably all these 

 losses would be avoided in operated 

 limits by systematic slash-burning. 



The Eastern Larch is attacked and 

 killed under certain conditions by 

 the Eastern Larch Bark Beetle, 

 Deudrocfonus simplex. Usually this 

 beetle confines itself to slash or to 

 completing the work of the larch 

 sawfly by killing the trees weakened 

 by defoliation. 



In addition to these more destruc- 

 tive species, other species of liark 

 beetles are each year responsible for 

 the death of considerable quantities 

 of Western Hemlock, Lowland or 

 Grand Fir, (Abies grandis) in British 

 Columbia, Alpine Fir (Abies lasio- 

 carpa) in Eastern British Columbia 

 and Western and Northern Alberta ; 

 and Balsam Fir (Abies balsaniea) in 

 Ontario, Quebec, and the Maritime 

 Provinces. The aggregate of these 

 minor injuries is very great, and in 

 the case of the Eastern Balsam is 

 particularly to be regretted since 



this tree is now being utilized for 

 pulp wood. A large part of this loss 

 could be averted on limits where 

 lumbering operations are being car- 

 ried on . 



Control of Bark Beetles. 



Although the bark beetles are so 

 destructive they can be controlled 

 efl:'ectively by destroying the broods 

 of beetles in the area infested. Each 

 of our destructive bark beetle species 

 has certain characteristic habits, but 

 in a general way the following state- 

 ment applies to all. The adult 

 beetles emerge in early summer 

 from the trees attacked early the 

 previous season and enter the bark 

 of fresh slash or green timber in 

 pairs through a round tunnel cut 

 directly through the bark to the 

 wood surface. When green trees 

 are attacked a mass of gum-tubes, 

 forms about the entrance hole and 

 serves to distinguish the fresh 

 "beetle trees" before the foliage 

 changes colour. The female con- 

 tinues the entrance tunnel between 

 the bark and wood as a vertical or 

 winding egg-tunnel, along the sides 

 of which she deposits her eggs at in- 

 tervals, or in layers. The larvae 

 bore away from the egg-tunnels in 

 the inner bark or between the bark 

 and wood, pupate in the ends of 

 their "larval mines," and finally 

 emerge from the bark early the fol- 

 lowing summer through round 

 "exit-holes" cut through the bark. 

 The winter is passed in the larval or 

 in the adult stage in the bark of 

 standing trees, logs or slash infested 

 the summer immediately preceding. 

 Dead trees are never re-infested. 

 The general principle to be followed 

 in their control is, therefore, to de- 

 stroy the broods during winter in 

 approximately 75 per cent of the in- 

 fested bark, selecting the most heav- 

 il}^ infested trees sot that approxi- 

 mately 7? per cent of the broods of. 

 beetles wil be destroyed. 



If the infested limit is being 

 logged, the beetle-infected logs are 

 treated so as to kill the broods in 



