INSECT ENEMIES OF PRINCIPAL CROPS 171 



characters stated, and illustrated in the figures of the last 

 column. 



Control. — These pests are so abundant that every apple 

 grower must fight them or suffer the loss of the best of his 

 crop. Poisons applied to the trees as sprays or as dust are 

 his chief reliance. Quite as important as knowing what 

 poison will kill an insect is knowing when and how to apply 

 it. State Agricultural Experiment stations issue "spray 

 calendars" giving this information. Everyone who raises 

 apples should follow the spray calendar applicable to his 

 own locality, even though he has but a single apple tree; 

 for the neglected tree is a nursery of pests, and may become 

 a center of infestation of a whole neighborhood. The person 

 who maintains such a nursery is not a desirable neighbor. 



