THE ENEMIES OF PLANT LIFE 



completed, but there was in it the germ of 

 a tremendous force. 



In Cahfornia a modification of this principle 

 is being applied with marked success, — ^the 

 destruction of injurious insects by other insects, 

 aiding Nature, when her balance has been dis- 

 turbed, to restore it to its normal poise, doing 

 that which neither man nor nature could do 

 alone. At intervals, the great fruit industry 

 of Cahfornia has been threatened through the 

 ravages of some insect. Now and then total 

 extinction of a fruit has seemed imminent. 

 Losses have been very heavy. Artificial pro- 

 tection through sprays, washes, fumigations, 

 and the like, have entailed large expense. 

 Having direct ocean communication with for- 

 eign countries where fruits grow in abundance, 

 exceptional opportunities are provided for the 

 introduction of pests by importation. For 

 example, it happened one day that a fruit- 

 grower imported a certain kind of lemon tree 

 which he thought would be an improvement 

 on the local stock, but it proved to be the 

 home of a tiny insect, a scale, very minute but 

 capable of marvelously rapid reproduction. 

 Its mission was to destroy foliage, blossoms 



89 



