33 



CONTROL MEASURES. 



This species prefers dying bark, and is everywhere found in slash and stumps 

 from cuttings. As long as cutting continues in a district, the slash and logs 

 usually supply abundant breeding places, and the subsequent treatment of the 

 logs removes many of the beetles. When the beetles become very numerous, 

 however, they may spread from the slash to surrounding green timber, and this 

 is to be feared if the cutting suddenly ceases. The beetles and their larvae winter 

 in the bark of the slash and logs, and regular winter slash-burning is therefore an 

 efficient method of control. Such work should be completed between early 

 October and the first of March. When it is required to control this beetle in 

 seasons during which little or no cutting occurs, over three-fourths of the infested 



Fig. 17 The Sitka Spruce Bark-beetle. (Dendroctonus obesus 

 Mannh.) Greatly enlarged. (Original). 



trees may be barked during winter; or the infested logs may be floated, or sawn 

 and the slabs burned before the middle of March. The unbarked portions of 

 the trunk and the slash should be burned during winter. 



INJURIES TO THE SITKA SPRUCE. 



The Sitka spruce occurs in British Columbia throughout the Coast region 

 and on Vancouver island. Its most injurious insect enemies are apparently the 

 Sitka Spruce Bark-beetle, and the Western Spruce Gall Louse. The former was 

 found this summer killing large timber, and is certainly an enemy which is able 

 to be very destructive. The Gall Louse is widespread and abundant, but 

 propably not of much importance in the forest; in parks and where spruces 

 are isolated, or in isolated groups, much serious injury is done by it. 



THE SITKA SPRUCE BARK-BEEILE (Dendroctonus obesus Mannh). 



This species is represented in our collections from Alaska along the coast and 

 islands south to the United States boundary. It probably occurs throughout the 

 Sitka spruce area and we have not yet obtaiaed it from any other tree. It 

 evidently prefers diseased and dying bark of stumps, logs, slash, and injured trees; 



