INSECTS 277 



Animal products $300,000,000 



Natural forests 100,000,000 



Products in storage 200,000,000 



$1,212,000,000 



Twelve hundred millions in a year that might be saved 

 if we knew just how to fight these tiny enemies instead of 

 fighting them in the dark ! It is like shooting into a forest 

 to hit enemies we cannot see. 



The study of insects is called entomology, and in the 

 employ of the state and national governments there are 

 many economic entomologists who devote their whole time 

 to finding out how to fight these very injurious insects. 

 As has been suggested before, one of the very best ways is 

 to find another insect that is an enemy of the injurious 

 one. Once such an insect is found, it is carefully bred 

 until a great hostile army of them has been produced. Then 

 these are set free to destroy the kind that is hurting the 

 crops, or the fruit-trees, or whatever it may be. In Cali- 

 fornia a certain kind of beetle (Vedalia) is kept in large 

 colonies by the State Horticultural Commissioner. There 

 is another kind of insect (cottony-cushion scale) that is 

 very bad for the oranges. Whenever there is danger of an 

 epidemic of the scale-insect, colonies of the beetle are sent 

 to the "firing-line," and they promptly exterminate the 

 cottony scale. This is a case in which almost perfect 

 control has been worked out, but it took many years to 

 do so, and the protecting insect was finally located hi far- 

 away Australia. Kellogg and Doane's "Economic Zo- 

 ology" is a very good book in which to read about the dif- 

 ferent kinds of injurious insects and the ways in which they 

 are combated. 



