414 ANIMAL STUDIES 



VedaUa, equally prolific and quick to spread from tree to 

 tree. 



The so-called San Jose scale, long known in California, 

 but probably introduced from Asia, is now the worst pest of 

 the orchards of the United States. It is found in 35 States, 

 and in most of these statutes exist aiming at its suppression. 



327. Amount of insect destruction. In 1864 the loss of 

 wheat and corn in Illinois caused by the chinch-bug 

 amounted to $73,000,000. In 1874 the total loss in the 

 United States amounted to $100,000,000. In 1874 the 

 Eocky Mountain locust destroyed in the States between 

 the Missouri River and the Eocky Mountains crops amount- 

 ing to $100,000,000. 



From 1864 to 1878 the cotton-worm in the Southern 

 States destroyed each year $30,000,000 worth of cotton. 

 The Hessian fly has often destroyed $50,000,000 worth of 

 grain in a single year in the United States. Ten per cent, 

 of the field-crops of our country are each year by noxious 

 insects. The annual loss from this source has been calcu- 

 lated to be $300,000,000. 



328. Prevention of insect ravages. These ravages can 

 not be prevented, but they can be materially checked. A 

 few examples of insect fighting may be given : 



The cottony-cushion scale was virtually exterminated by 

 the introduction of its enemy at home. This can be done 

 with various other species. 



In Indiana the destructive corn-root worm was destroyed 

 by rotation of crops, introducing something on which the 

 larvae could not feed. 



Many insects are killed by insecticides, washes, and 

 sprays, or by fumigation with gas. The Department of 

 Agriculture maintains a division devoted to insect fight- 

 ing. It costs now about $75,000 a year, and saves the 

 farmers and gardeners many times that amount. 



The preservation of insect-eating birds is an effective 

 method of insect fighting. 



