U. S. D. A., B. E. Bui. 58, Part V. F. I. I., December 4, 1909. 



SOME INSECTS INJURIOUS TO FORESTS. 



INSECT DEPREDATIONS IN NORTH AMERICAN FORESTS 

 AND PRACTICAL METHODS OF PREVENTION AND 

 CONTROL. 



By A. D. Hoi'KiNS, Ph. D., 

 In Charge of Forcxt Insect Investigations. 



INTRODUCTION. 



It is the purpose of this part of the bulletin to give a summary of 

 facts, conclusions, and estimates relating to the forest-insect problem 

 as applied to North American conditions and to call attention to its 

 importance in the future management of private, state, and national 

 forests. 



The matter is presented in as brief and concise a form as possible, 

 in order that the information may be readily available to the general 

 reader, as well as to the forester and student, and references are 

 made to publications in Avhich more detailed accounts may be found. 



The statements and conclusions relating to the insects and their 

 work and to methods for their control are based almost entirely on 

 investigations and observations by the writer and by assistants in 

 the Bureau of Entomology working under his direction, carried on 

 in all of the principal forest areas of the United States. The his- 

 torical data have been gathered from the publications listed on 

 pages 9C-97. The estimates of the amount and value of standing tim- 

 ber killed by insects and of the forest products destroyed and reduced 

 in value through insect injuries to the crude and seasoned products 

 are based on our published results of investigations (pp. 97-100) , on 

 unpublished notes, on technical and practical knowledge of the sub- 

 ject, and on the published forest statistics relating to the amount and 

 value of timber, fire losses, etc. (pp. 100-101). 



INSECT DEPBEDATIONS IN NORTH AMERICAN FORESTS. 

 CHARACTER AND EXTENT OF DEPREDATIONS. 



The records of notable depredations by insects on the timber sup- 

 ply of Europe during the past four hundred years, on that of the 

 61830°— Bull. 58—10 5 5T 



