336 AMERICAN FORESTRY 



with this species that the first of these circulars deals. The principal species 

 iu extent of their depredations are the southern pine beetle, eastern spruce 

 beetle, Engelmann spruce beetle, Black Hills beetle, mountain pine and western 

 pine beetles, Douglas fir beetle, and hickory bark beetle. 



The southern pine beetle is one of the most dangerous insect enemies of 

 southern pines. The eastern spruce beetles ravaged the spruce forests of New 

 York, New England and southeastern Canada prior to 1900. The Engelmann 

 spruce beetle, with habits similar to the last named species, has frequently 

 done serious damage in Engelmann spruce forests in the Rocky Mountain 

 region. The Black Hills beetle is one of the most destructive of the forest 

 beetles, and during ten years is estimated to have destroyed more than a 

 million feet of timber in the Black Hills National Forest. It is distributed 

 throughout the middle and southern Rocky Mountain regions. The mountain 

 pine and western pine beetles attack the sugar, silver, western, yellow and 

 lodgepole pines of the region north of Colorado and Utah, westward to the 

 Cascades, and southward through the Sierra Nevadas. The Douglas fir beetle 

 occurs wherever that tree does. The hickory bark beetle has caused heavy 

 loss in the last ten years from Wisconsin to Vermont and southward to central 

 Georgia. 



The bark beetles which kill trees attack the bark on the trunk and destroy 

 the life of the tree by extending their burrows, or galleries, in all directions 

 through the inner, living bark. The broods of young grubs or larvae develop 

 within the inner bark on which they feed. Those of some species develop to 

 the adult stage within the inner bark and are exposed when the bark is 

 removed, while tliose of other species transform to the adult in the outer corky 

 bark, and the larvae are not exposed when the bark is removed. Some species 

 have two or more generations in a season, or annually, while others have but 

 one; and in a few species it requires two years for a single generation to 

 develop. From this knowledge of life-history and habits of beetles of this class 

 are derived general directions for their control, which are embodied in the 

 following rules: (a) Give prompt attention to the first evidence of a destruc- 

 tive outbreak as indicated by an abnormal percentage of yellow or red topped 

 dying trees and especially when such trees occur in groups of ten or more, or 

 cover large areas; (b) secure authentic determination of the particular species 

 of insect responsible for the trouble; and (c) take prompt action towards its 

 control according to specific expert advice. Some of the methods to be adopted 

 to meet the requirements of local conditions are as follows: 



(1) Utilize the infested timber and burn the slabs during periods in 

 which the broods of destructive beetles are in immature stages, or before the 

 developed broods emerge from the bark. 



(2) Fell the infested trees and remove bark from the main trunk and 

 burn the bark, if necessary. 



(3) Remove the infested bark from the standing timber and burn the 

 bark when necessary. 



(4) Immerse the unbarked logs in ponds, lakes or streams where the bark 

 will remained soaked long enough to kill the insects. 



(5) Remove the unbarked logs or products to a locality where there are 

 no trees liable to attack within a radius of twenty miles or more. 



The circular further suggests an insect control policy by which groups of 

 dying trees can receive as prompt attention as that required for the prevention 

 or control of forest fires. In state and national forests those in charge should 

 have equipment and instructions for locating beetle-infested trees and for 

 taking necessary action. In private forests the owners should be led to under- 



