20 



cut will be effective. When the Western Pine Bark-beetle is concerned, summer 

 slash burning in early August would assist in its control, in addition to winter 

 burning for the summer's cut. 



THE WESTERN WHITE PINE BARK-BEETLE (Dendroctonus monticolce Hopk.) 



The Western White Pine Bark-beetle is very similar in appearance and 

 habits to the species just discussed. A fuller account of the beetle and of its 

 work in western white pine is given later in this report. When found working 

 in bull pine it may be distinguished from brevicomis by its larger size, being 

 one-sixth to one-quarter of an inch in length, and by the long sparse hairs on 

 the hinder part of the wing-covers. The pubescence on the wing-covers of the 

 Western Pine Bark-beetle is denser and very short, and the sides of the pronotum 

 are longer and more nearly straight. 



The egg-tunnels of the Western White Pine Bark-beetle are usually dis- 

 tinctly larger than those of the Western Pine Beetle. They are vertical, nearly 

 straight or slightly winding and elongate, with the eggs placed singly in niches, 

 which are cut a few in a group at short intervals along the sides. 



The two species are found working in the same trees in the infested bull 



Eine about Princeton, and appeared this season to be about equally responsible 

 >r the injury, although there are indications now that the Western White 

 Pine Beetle is in some places the more destructive. 



When the Western White Pine Beetle is the only species involved in an out- 

 break it is not necessary to burn the bark; the broods of this species are found almost 

 solely in the inner bark and are exposed when the bark is removed. The simple 

 removal of the bark from the infested trees during winter and early spring is 

 sufficient to effect control. When, however, as is the case at Princeton, the 

 Western Pine Beetle is also concerned, the bark must be burned, if bark removal 

 is the control method adopted. 



Before undertaking control work an exact determination should be made of 

 the species of beetles primarily responsible for the death of the trees. 



THE RED TURPENTINE BARK-BEETLE (Dendroctonus valens Lee.) 



This species, the largest of our bark-beetles, is from one-fifth to one-third 

 of an inch in length, yellowish to reddish-brown in colour; epistomal process 

 broad, with the sides oblique; pronotum with large punctures, rather regular 

 in size; the elytra sparsely clothed with long hairs which extend nearly to the 

 base. 



It is found in British Columbia in stumps and dying trees of bull pine, 

 Engelmann's spruce and probably other pines and spruces. 



This species confines itself chiefly to the base of the tree, within a few feet 

 of the ground. A pair of adult beetles excavate a wide egg-tunnel through the 

 inner bark, upon the wood surface. This tunnel is more or less elongate, irregu- 

 larly widened above the entrance-hole and usually vertical at first in standing 

 green trees. Later the tunnel is frequently branched and often extended down- 

 wards. The eggs are laid at intervals in layers or irregular elongate masses 

 against the widened side of the egg-tunnel and covered more or less completely 

 with boring-dust. 



The larvae hatch in about ten days, and feed in congress away from the 

 egg-tunnel through the inner bark, leaving a wide, flat cavity, largely filled 

 behind them with reddish excrement. 



This species is not so destructive as the two just discussed. It commonly 

 breeds in the bark of stumps and in the base of trees dying from other injury. 

 It does, however, attack and even kill apparently healthy trees, and renders 

 able assistance to the more destructive species in killing the bull pine in British 

 Columbia. Its work in sound trees often results in irregular scars about the 



