THE PROGRESS IN FOREST ENTOMOLOGY 



By the Division of Forest Insects, Bureau of Entomology 



CONTENTS 



Importance of forest insects 723 



Development in forest-insect control 726 



Cooperation between the Bureau of Entomology and other Federal agencies 



in insect control 728 



Forest insects and forest management 729 



Forest insects and forest products 730 



Beneficial forest insects 731 



Insects and fungi 731 



Conclusion 732 



The progress of forest entomology in this country has been inti- 

 mately associated with the broader problem of forest protection and 

 to some extent with forest management. The control of bisect 

 outbreaks or the prevention of losses from insect attack has been the 

 stimulus for research aimed at accomplishing these ends. Investi- 

 gation of forest insects and the development of control methods are 

 a function of the Bureau of Entomology; the application of control 

 methods that of the Forest Service and of other land-administering 

 agencies. 



IMPORTANCE OF FOREST INSECTS 



There is a continuous attrition in our forests from the activities of 

 many different kinds of insects. All stages in the development of 

 the stand, from the seedling to the mature plant, are liable to insect 

 attack at one time or another and in some years even the developing 

 seed crops are destroyed. In virgin timber stands, particularly those 

 which are overmature, a normal loss is going on steadily as the result 

 of insect activity and decay, but such loss for the most part is offset 

 or, in some cases, exceeded by growth. Counterbalancing of growth 

 against loss obviously results in no marked change in the forest 

 capital. On the other hand, epidemic insect outbreaks occurring 

 from time to time definitely deplete the forest capital to such an 

 extent that long periods are required for eventual replacement. 

 For instance the western pine beetle in southern and central Oregon, 

 during the past 10 years, has caused a net depletion of the ponderosa 

 pine stand amounting to 2,240 million board feet. One typical 

 section on the Klamath Indian Reservation carrying a stand of 

 11,074,000 board feet in 1921, lost 3,875,000 board feet through 

 barkbeetle attack during the period 1921-32. The growth, which 

 was only 48 percent of normal due to drought and a defoliation by 

 the Pandora moth amounted to 294,000 board feet leaving a net 

 loss for the 11 years of 32.2 percent of the stand. 



The total losses in the United States from all sources have been 

 variously estimated at $100,000,000 to $150,000,000 a year. This 

 includes depredations by such insects as the mountain pine beetle, 

 the Black Hills beetle, the western pine beetle, the pine butterfly, 



723 



