I go PRINCIPLES OF FARM PRACTICE 



Timing farm operations. The timing of work in the 

 field has an effect on insect control. The value of timing 

 farm operations is well illustrated by the success of measures 

 that are practiced to protect wheat from injury by the Hessian 

 fly. If a field in which the Hessian fly has been troublesome 

 is to be used for wheat the following year, plowing and rolling 

 the ground in summer and late sowing will usually save the 

 next crop from much damage by this insect. Plowing and 

 rolling destroy most of the insects, and the preparation for 

 late sowing destroys the eggs of the flies that have escaped 

 destruction in the first operation. A similar practice is 

 followed in the control of the wheat jointworm. Where 

 spring wheat is to be protected, burning the stubble and 

 plowing in the fall, and early spring sowing are regarded 

 as efficient measures. It must be understood that the Hessian 

 fly and the jointworm are not always controlled by these 

 methods. They should be employed, however, where rota- 

 tion of crops which is a more effective means of control can 

 not be followed. 



Relation of moisture and other climatic conditions to 

 insects. Many insects are greatly influenced by climatic 

 conditions, especially by moisture. This fact is worthy of 

 consideration in insect control, for if conditions are favorable 

 for their growth and development some measures for control 

 may be necessary. For example, the greatest damage from 

 the chinch bug may be expected during a hot, dry summer; 

 and from the Hessian fly during a warm, moist spring or fall. 



Soil fertility and insect control. Keeping the soil fertile 

 is a good practice not only from the standpoint of crop yield 

 under normal conditions, but also from the standpoint of 

 safeguarding the growing crop from a certain amount of dam- 

 age by insects. Vigorously growing, healthy plants are less 



