P>irds &$ Conservatory of tf)e Forest 



By F. E. L. Beal.* 



THE enemies of the forest may be roughly grouped in three categories — 

 vegetable enemies, such as fungi and bacteria; invertebrated animals, 

 mostly insects; and, lastly, vertebrates. These will include birds, mice, 

 rabbits, etc., and, most destructive of all, man. Of the three groups, the second is 

 by far the worst in its effects, and is the most difficult to combat. There is prob- 

 ably not a single species of land plant which does not have an insect enemy that 

 preys upon it, and most of them have several, while the trees of the forest 

 furnish food for a legion. In the Fifth Report of the United States Entomological 

 Commission, over 400 species of insects are recorded as preying upon the oak, 

 and the opinion is expressed that this number is far below what are actually in 

 existence. In the same work the elm is said to have about 80 species which feed 

 upon it, the hickory 170, the locust 41, the maples 100, the birch 105, the willow 186 

 and the pine 165, and in each case the list is confessedly incomplete. 



On this point Dr. Hopkins has said: 



"The results of investigations lead to the conclusion that the annual loss from 

 insect work on forest trees, and their crude and finished products, amounts to at 

 least one hundred million dollars. 



"No period in the life history of a tree is exempt from insect attack, and 

 every part, from the smallest roots to the terminal buds, leaves, flowers and fruit, 

 may be infested by one or many species. The seed in the ground, the tender 

 shoots of both roots and stems, and the young seedling, to the matured tree, 

 may all be attacked by special enemies which injure or destroy different parts or 

 the entire plant. In fact, living, diseased, dead, or decaying, a tree may be the 

 home of hundreds of species and thousands of individuals of insect life. " f 



From these considerations it may be seen at once how important any agency 

 must be which will in any considerable degree reduce or restrain this great army 

 of tree destroyers. 



* Biological Survey, U. S. Dept. Agr. 



f From Lecture on Forest Insects and Their Destructive Work; by Dr. A. D. Hopkins, in 

 charge of Forest Insect Investigations, Bureau of Entomology, U. S. Dept. Agr. 



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