18 



FLOATING THE LOGS. Where water is available, the simplest method is 

 to cut during winter and float the infested logs as soon as cut or as early in 

 spring as possible. This will kill the greater part of the brood. 



SAWING DURING WINTER AND BURNING THE SLABS. Where it can be done 

 profitably, the infested logs may be sawn during winter, and the slabs, which 

 will contain the brood, burnt before spring opens. 



BARKING THE TREES. It is always possible to fell and bark the infested 

 trees during winter and, when this species is concerned, to burn the infested 

 bark before spring opens. The presence of the greater number of the grubs 

 in the middle layers of bark, renders burning the bark necessary in the control 

 of the outbreaks involving the Western Pine Bark-beetle. Control operations 

 must be completed during the period between the first of November and the 

 following June; but should be finished as early in spring as possible. 



When it is not possible to utilize the timber profitably, and control measures 

 are necessary to protect valuable holdings against ravages of the beetles, the 

 infested trees should be treated by the cheapest effective method so as to destroy 

 the contained brood. The infested trees may be cut and burnt before spring 

 opens, frequently at less expense than by removing and burning the bark. 

 By means of a special barking tool, the bark may be removed from a sufficient 

 number of the standing infested trees to effect partial control. The bark should 

 be burnt. 



This control work has reference solely to the freshly-infested trees, with 

 green, yellowish, or moderately reddened foliage, having the bark filled with 

 the beetles and their grubs, and not to the old " red-tops" which have been 

 dead for from one and a half to several years, and from which the beetles have 

 emerged. 



It will often be best to combine two or more of these methods in order to 

 complete the control work during late fall, winter and early spring. 



The control measures outlined above should be followed in control work 

 with the Princeton outbreak, together with the barking of infested stumps, 

 as recommended under the "Red Turpentine Bark-beetle. " 



THE RELATION OF SLASH TO BARK-BEETLE OUTBREAKS. 



In order to control the bark-beetles known to be injurious in British Colum- 

 bia, it is only necessary to reduce the numbers so that the normal amount of 

 dying bark to be found in the woods will suffice for breeding purposes. So 

 far as we know at present all our bark-beetles prefer dying bark, and it is only 

 when their numbers are very great that green timber is attacked in quantity. 

 It therefore follows that so long as extensive cutting in a district continues, 

 the slash and stumps serve as a breeding-place and to a considerable extent, 

 or for a time often entirely protect the healthy trees. But unless the amount 

 of slash increases from year to year, certain species are bound to develop to 

 such numbers that additional breeding-places are required; and then, or, with 

 certain species, before that stage is apparently reached, they attack the sur- 

 rounding green timber. When cutting ceases suddenly there is always danger 

 that an outbreak may develop in the neighbourhood. 



It will be seen from the above that while slash may serve for a longer or 

 shorter time as a protection to the standing timber, it may become a nuisance, 

 in as much as it offers abundant food supply for the beetles, in which they may 

 breed to immense numbers. 



The slash can be made to serve as an effective trap. Many injurious 

 species will pass the winter mostly as young adults or larvae in the bark. If 

 the slash of the previous summer's cutting is burned during winter and early 

 spring a sufficient number of the beetles will usually be killed to hold the in- 

 jurious species in check. When there is but one brood each season, as with the 

 Mountain Pine Bark-beetle, winter burning of slash of the previous winter's 



