DESTROYERS OF INSECT PESTS 



69 



and the forest tent-caterpillar destroys forest-trees. 

 Nearly all crops have a great variety of different 

 kinds of insects that may prey upon them. One 

 hundred and seventy-six kinds have been found 

 preying on the apple tree alone and four hundred 

 kinds on the oak. 



The following table prepared by the United 

 States Bureau of Entomology gives an estimate of 

 the annual loss caused by insects in the United 

 States : — 



Besides the tremendous loss caused directly by 

 the insects in destroying the crops, man spends an- 

 nually millions of dollars for spraying outfits and 



