THE INSECT WORLD. 



109 



foreign country where it was on the whole rather scarce and kept 

 in check by natural enemies ; 2d, its introduction into America, 

 where these natural enemies did not exist, and where the insect 

 found favorable opportunity for multiplying ; 3d, the introduction 

 of some of its foreign parasites and of the predaceous insects 



feeding upon the species ; lastly, and most important of all, the 

 Australian lady-bird recognized no other insect among those 

 found in California as proper food, and naturally confined itself 

 entirely to these scales. The contest was unequal, and the scales 

 lost rapidly, soon becoming nearly or quite exterminated. The 



