VI CONTENTS. 



Insect depredations in North American forests — Continued. 



Interrelations of forest insects aiid forest fires— Continued. Page, 



Destruction of insects by fire 68 



Durability of insect-killed timber . . 69 



Interrelation of forest insects and forest fungi 69 



Decay following injury by insects 69 



Summary and estimates relating to character and extent of insect damage. 69 



Standing timber killed and damaged by insects 70 



Reduction in the Nation's wealth 71 



Reduction in cash revenue 71 



Reduction in value of finished and commercial products 71 



Methods of prevention and control 71 



General principles of control 72 



Control of barkbeetles which kill trees 73 



Maintaining control of barkbeetles 74 



Examples of successful control of barkbeetles 75 



Control of insects which cause defects in living timber 78 



Prevention of injury to dying and dead trees 78 



Prevention of loss from insect injuries to natural and artificial reproduction. 79 



Utilization of immune and resistant varieties and races of trees 79 



Prevention of insect injuries to forest products 79 



Crude products 79 



Manufactured products 81 



Unseasoned products - 81 



Seasoned products 81 



Past and present conditions of powder-post injury 82 



Tan bark 83 



Utilized products 83 



Timbers and woodwork in structures 83 



Utilization of natural enemies and factors in the control of injurious 



insects 85 



Beneficial insects 86 



Beneficial diseases of insects 86 



Beneficial birds -- 86 



Beneficial climatic conditions - 87 



Utilization of waste caused by insects 87 



Present conditions and opportunities 88 



Forest entomology as applied to American forests 88 



Present knowledge 88 



Needs 89 



Elementary and technical knowledge of forest entomology for the 



forester 91 



Present requirements of instruction 91 



Conclusion 91 



General estimates of amount of damage caused by forest insects 92 



How losses can be prevented 93 



Publications relating to forest insects 96 



Historical and general 96 



Prepared by oflacials of the branch of Forest Insect Investigations, Bureau 

 of Entomology, and of the West Virginia Agricultural Experiment 



Station 97 



Publications relating to forest statistics 100 



Forest resources 100 



Forest fires 101 



