n 



dred prey upon the bending willow. The birches 

 supply food to about three hundred of these 

 predacious fellows, while poplars feed and shel- 

 ter almost as many. The pines and spruces are 

 compelled permanently to pension or provide 

 for about three hundred families of sucking, 

 chewing parasites. 



The recent ravages of the chestnut- tree blight 

 and the appalling depredations of the gypsy 

 and brown-tailed moths, together with other 

 evils, suggest at once the bigness of these pro- 

 blems and the importance of their study and 

 solution. The insect army is as innumerable as 

 the leaves in the forest. This army occupies 

 points of vantage in every part of the tree zone, 

 has an insatiable appetite, is eternally vigilant 

 for invasion, and is eager to multiply. It main- 

 tains incessant warfare against the forest, and 

 every tree that matures must run a gantlet of 

 enemies in series, each species of which is armed 

 with weapons long specialized for the tree's de- 

 struction. Some trees escape unscarred, though 

 countless numbers are killed and multitudes 

 maimed, which for a time live almost useless 



185 



