1 88 PRINCIPLES OF FARM PRACTICE 



and development. He should be able to recognize the prin- 

 cipal insects and the injuries caused by them to which his 

 crops are liable. He should realize the importance of insect 

 control to profitable farming. He should know the effects 

 of rotations, arrangement of crops, time of planting, time 

 of plowing, and the like on the important crop pests; the 

 relation of moisture, climatic conditions, fertility, etc., to 

 insect damage; the great importance of timeliness in recogniz- 

 ing insect troubles, and in taking measures for their control; 

 and especially should he understand the value of calling 

 upon his agricultural experiment station for assistance if 

 the trouble is unknown to him or if he is not thoroughly 

 familiar with he best methods of procedure. 



What the farmer can do to control insect injuries. The 

 control of insects is an important and difficult task for the 

 farmer, but there are many things he can do toward this 

 control. It is to his advantage to know such facts of insect 

 life as have already been set forth in this chapter. He should 

 not only be able to recognize the various kinds of common 

 insects but should have an acquaintance with their life- 

 histories and habits. For example, if he knows by sight the 

 moths of the army worm, and happens to notice that they 

 are unusually plentiful in the spring, he will be prepared to 

 see large numbers of the young later and perhaps be able to 

 destroy them near their hatching grounds before they do 

 much damage. 



The following are some of the methods for controlling 

 insect injuries: 



Crop rotation. The kind of rotation practiced may 

 affect the kind and amount of insect injury to crops in the 

 rotation. For example, as a result of the change from sod 

 (grass) to corn, some of the insects, such as the white 



