MEASURES FOR INSECT CONTROL 323 



happens that corn planted on sod land is in this way very 

 seriously injured. The precaution should be to plow under 

 long enough before the new crop is planted to allow oppor- 

 tunity for the starving out of insects which may be present 

 in the grass. 



Another practise in this line is for such an arrangement of 

 crops that insects which naturally migrate from one crop to 

 another will be sejjarated by a crop of different character, 

 something that will not serve them as a food supply. For 

 instance, the migration of the chinch bug from wheat fields 

 into corn fields may be prevented by the introduction of a 

 strip planted to potatoes, beans or some crop which is not 

 available as chinch bug food. 



The use of an early planted crop for the purpose of attract- 

 ing insect egg deposition wuth the view of destroying the 

 insects so attracted and thus protecting the later crop, has 

 been in vogue for many years and is applicable to such 

 species as have several generations in a season. A good 

 example of this is the corn-ear worm which if attracted to 

 a small area of early planted corn which is fed to hogs at the 

 time the worms begin work will assist much in the preven- 

 tion of attacks on adjacent fields. 



In some cases where an insect is especially destructive in 

 a certain area, resort may be had to the suppression of the 

 cultivation of a crop for one or two seasons, thus eliminating 

 food. This will largely diminish if not practically extermi- 

 nate such insects as are strictly dependent upon this crop for 

 existence. Naturally such a method is limited in application, 

 as the complete suppression of any crop in a certain district 

 is a difficult matter to accomplish. 



Clean culture is often recommended as an important 

 aid in the suppression of insects, and there is no doubt that 

 for many species attention to the elimination of food plants 

 which assist them to survive and the cleaning up of litter 

 in which they may hibernate will accomplish a great deal 

 in the reduction of numbers and the consequent extent of 

 injury. Clean culture, however, must be taken in connec- 

 tion with a study of the habits of the species wdiich it is 



