U. S. D. A.. H. K. I'.iil. r.s. r.irt V. F. I. I., Uecembcr 4, I'JU'J. 



SOME INSECTS IXJURIOUS TO FORESTS. 



INSECT DEPREDATIONS IN NORTH AMERICAN FORESTS 

 AND PRACTICAL METHODS OF PREVENTION AND 

 CONTROL. 



INTRODUCTION. 



It is the purpose of this part of Iho bulletin to <xivo a summary of 

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

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

 importance in the future management of private and public forests. 



Tlie 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 pul)lications in which 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 writ(>r 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 90-07. The estimates of the amount and value t)f standing tim- 

 l)er 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 i^ublished results of investigations (pp. l>7-100), on 

 unpul)lished notes, on technical and practical knowledge of the sub- 

 ject, and on the |)ublished forest statistics relating to the amount and 

 value of timber, lire losses, etc. ( ])p. lOO-lOl). 



INSECT DEPREDATIONS IN NORTH AMERICAN FORESTS. 



CHAR.VCTEK AND EXTENT Ol' DEPREDATIONS. 



The records of notable depredatit)ns by insects on the timber sup- 

 ply of Europe dui'ing the [)ast four hundred year>, on that of the 



