27 



BIRDS. 



Insectivorous birds, particularly the woodpeckers, are decidedly beneficial 

 in destroying the broods of bark-beetles whenever their numbers are sufficiently 

 great. Beetle-infested trees are often found with the bark largely riddled by 

 woodpeckers, and the broods almost entirely destroyed. In the beetle-infested 

 yellow-pine area of southern British Columbia the woodpecker work is some- 

 times strikingly evident, and the beetle trees may often be detected in this way 

 (PI. 7, fig. 4). There is evidence that the birds have at times a decided effect 

 in reducing the numbers of the beetles over a limited area; but while their influ- 

 ence on the whole is decidedly beneficial, they are probably never sufficiently 

 numerous in our woods to control more than very small sporadic outbreaks. 



PARASITIC FUNGI. 



The effect of parasitic fungi in destroying broods of bark-beetles has been 

 studied in several instances. This factor appears to be of minor importance 

 in our forests. 



METHODS OF CONTROL. 



Sporadic outbreaks by bark-beetles may usually be controlled without 

 great difficulty; and even epidemic outbreaks, in which many hundreds of trees 

 are dying, may be brought under control, often with very little actual loss. 

 The peculiar habits of the beetles render them vulnerable to attack by the only 

 methods the lumberman could feasibly employ. Our most destructive species 

 have one brood, or one brood and a partial second one, each season; they pass 

 the winter as adult beetles and larvae in the bark of the dying trees, entered by 

 the parent adults in the early part of the same season. When in green timber 

 the broods always pass the winter in the trees attacked by their parent beetles 

 earlier in the same season, then usually with yellowing foliage and often with 

 resin-tubes and woodpecker work showing on the bark of the trunk. The 

 beetles never return to the old " red-tops," as the affected trees are called, 

 nor remain in the trees longer than one year. If then, by modified logging 

 operations, these green " beetle trees " can be removed during winter, kept 

 separate, and so treated that the broods in the bark will be killed before their 

 breeding season opens, it is possible to stop the outbreak in one season. If all 

 the green beetle-trees could be treated and all the slash and broken trees burned 

 it would be possible, at least in theory, to exterminate the injurious species 

 from a limit in one winter's work. Practically, this would not be possible in 

 dealing with an outbreak of any extent; but it is fortunately unnecessary. If 

 over three-fourths of the broods in the infested trees can be killed before they 

 emerge in the early season, the outbreak can be checked; and by similar work 

 upon the relatively few trees attacked the succeeding season, it can be brought 

 under nearly complete control, provided the entire infested section is treated, 

 so tEat there will not be extensive reinfestation each year. The largest and 

 most heavily infested trees and the most heavily infested sections should receive 

 special attention. When only a portion of the infestation can be treated each 

 season, it is usually considered advisable to direct the work towards reducing 

 as rapidly as possible the chief centres of infestation in the whole infested section. 

 What portion of the second year's work should be employed in new territory, 

 and how much towards cleaning up more completely on the ground covered 

 during the previous winter, must be decided by the conditions of the locality. 

 The details of the control methods will depend upon the species of beetles 

 involved, and partly also upon local conditions, and should be undertaken with 

 the direction of a competent forest entomologist. 



