8 FRUIT INSECTS 



trees that are in a vigorous, healthy condition from proper 

 cultivation are as a rule less subject to spray injury and are, 

 therefore, able to receive stronger and more frequent applica- 

 tions of insecticides without danger. 



Crop rotation. 



In the case of strawberries and some other small fruits a fre- 

 quent rotation of crops will tend to clear the land of many 

 insect pests which cannot be reached satisfactorily in other ways. 

 This is particularly true of wire-worms, white grubs and the 

 strawberry root-worm. 



