1911 ENTOMOLOGICAL SOCIETY. 87 



have been but little sappy bark for the parents of the second brood, and they would 

 have scattered from the region, leaving a very small and harmless second brood. 



The pest level of D. simplex is high. It is perhaps rarely injurious. But the 

 pest level of certain species attacking pine and spruce is low, and when that level 

 is reached the finest trees of the region are in danger. 



It can be easily seen from this that careful destruction of wastes from cutting 

 is of utmost importance in lumbering operations, the more so that many other 

 forest insects breed in such dying bark and wood. 



The conditions which obtained in this larch bush will be found everywhere 

 in Canada, in the woodlots, in the lumbering districts, and in our virgin forests. 



In the great forests under natural conditions we find that when, through the 

 agency of forest fires, heavy storms or the attacks of other insects, scolytid beetles 

 find much dying bark in a suitable condition, they breed in this until they reach 

 their pest level for those conditions; tlien they attack and kill the healthy trees. 

 Witness the terrible destruction of D. piceaperda in the spruce of Maine and New 

 Brunswick, as described by Dr. Hopkins. 



In the lumber woods the present careless method of cutting leaves culls and 

 refuse to breed these beetles and other forest pests by myriads. 



I pointed out a few moments ago that scolyiid beetles followed forest fires, 

 breeding in the dying bark of injured trees. Dr. Hopkins, the leading forest ento- 

 mologist of America, has shown that the relations are at times reversed; so that 

 fires which would otherwise have caused no considerable injury, gain headway in 

 districts of forest devastated by these beetles, and sweep as great conflagrations 

 over square miles of territory. 



It is well to discuss the injury which these forest insects are known to do, but 

 can anything be done to check them in our timber limits and in our great forests ? 



The control of certain forest insect pests, e.g., the larch saw-fly, is, so far, 

 beyond man's ability. But a method of control has been worked out whereby many 

 forest pests, chiefly Scolytidse, can be effectively kept below the pest level. Such 

 methods have been successful in European forests, and in certain sections of the 

 United States, and will most surely be followed in Canadian forests in years to 

 como. They consist in modifications of the methods of cutting. Injured trees, 

 with the bark filled with thousands of these beetles, are cut, and either barked or 

 got into the water before the beetles emerge to start their tunnels in other trees. 

 Either the barking, if done at the right time, or the immersion in water, destroys 

 the gTeater part of the larvre or adults. These beetles seem, perhaps invariably, to 

 prefer dying bark. Therefore by girdling, early in the season, trees selected for 

 later cutting, the greater part of the beetles in the immediate neighborhood can be 

 attracted to the bark of these " trap-trees," and later these trap-trees are barked or 

 got into the water early, so that the contained brood will be killed. The refuse, 

 tops and branches, are destroyed, removing what would otherwise be a suitable 

 breeding-ground for many species. 



Such modifications in methods of cutting can be relied upon when control is 

 needed. 



Before such methods can be outlined, however, it is necessary to obtain much 

 information from forest entomologists. The insect pests of our Canadian forests 

 luvve been studied but little. There are many injurious forest insects in Northern 

 Quebec and Ontario about which we know absolutely nothing. There is much work 

 to be done, therefore, by the systematist ; work which is absolutely essential. The 

 practical entomologist must be able to distinguish with certainty the injurious 



