632 



Canadian Forestry Journal, July, ipi6. 



Ravages of Insects in Canadian 

 = ^^^ Forests ; 



In Valuable Limits, the Cost of Piling and Burning 

 Slash is Offset by Saving from 

 Insect Injuries 



By J. M. Szmine. 



In Charge of Forest Insect Investigations. Entomological Branch, Ottazva 



(Article Concluded from June Issue.) 



The most serious insect-enemies 



of our forests are various species of 

 bark-beetles. The adult beetles, 

 usually less than one-quarter of an 

 inch long, and brown or black in 

 color, cut cylindric tunnels between 

 the bark and wood of nearly all our 

 timber trees. The eggs are laid 

 along the sides of the egg-tunnels, 

 and the grubs bore away from the 

 egg-tunnels usually between the bark 

 and the wood, and coring both. 

 When green trees are attacked the 

 liquid resin forms about the entrance 

 hole to form a gum tube on the 

 bark ; and the trunk being girdled in 

 hundreds of places by the egg-tun- 

 nels and larval mines, the death of 

 the tree usually results within one 

 year. 



Many species of Bark-beetles at- 

 tack badly weakened or dying trees 

 or those recently killed ; others oc- 

 casionally attack and kill healthy 

 trees, and commonly assist in the 

 attack by more destructive species ; 

 these last, a limited number of 

 sp ■ 



being kileld out. whenever it occurs 

 in British Columbia, by the Moun- 

 tain Pine Bark-bettle, Dendroctonus 

 uionticolae. Whenever we have 

 found the Mountain Pine, from Van- 

 couver Island as far east as Glacier 

 Park, this beetle has been busy at 

 its destructive work. There are 

 very few valuable stands of white 

 pine left in British Columbia and the 

 chief agent in its destruction has 

 been its inveterate enemy, the 

 Mountain Pine Beetle. Unless con- 

 trol measures are undertaken very 

 soon there will be no White Pine of 

 timber size in that province. 



The Western Yellow Pine or Bull 

 Pine, Finns ponderosa occurs in large 

 forests over an irregular area in 

 Southern British Columbia. For 

 several years past a great outbreak 

 of bark-beetles has been spreading 

 throughout the Similkameen coun- 

 try. The present outbreak started 

 apparently about eight or nine years 

 ago about Okana^an lake, and has 



ecies, belonging mostly to the spread from the western slopes of 



genus Dendroctonus, are recognized 

 primary enemies, readily attacking 

 and killing the finest trees, and at 

 times occurring in great outbreaks 

 quite as destructive as a forest fire. 

 I shall ni^p ti'on a few of these pri- 

 mary enemies. 



Enemy of White Fine. 

 The We'^tern White Pine or 



the Gold Ranp-e as far west as 

 Princeton and Nicola. A few days 

 ago we received a report of the 

 death of a large area of timber near 

 Nicola Lake, and the valleys to the 

 west of Merrit are threatened. In 

 the districts longest affected, or 

 where the beetles have spread most 

 actively, all the pines, both yellow 

 '^hie and black pine, are dead, and 



Mountain Pine, Finns monticola is the country appears as though swept 



