Insect Enemies and Allies 



201 





W. T. Stilling 



FIG. 153. Beans that have been weevil-eaten. Weevils are destructive both 

 in the larval and in the adult stage 



insects that feed upon them. The latter are called 

 " predacious insects." 



The way in which insects multiply if. freed from their How the 

 natural enemies was shown some years ago when the jj^En 

 cottony-cushion scale was introduced from Australia scale was 

 into California. In its native country it had not been a 

 very serious pest, but here it did millions of dollars' worth 

 of damage and threatened to destroy entirely the citrus 

 trees and a number of other kinds of trees. Search was 

 made for an insect that would destroy this pest, and in 

 Australia was found a beetle known as the " Australian 

 ladybird," which devoured the cottony-cushion scale 

 in that country (Figs. 154, 155, 156, and 157). A few 

 of these ladybird beetles were brought to America and 



