FARM METHODS FOR THE CONTROL OF INSECTS 35 



weeds during the larval stage, while the adults attack all sorts of 

 garden crops. In many cases caterpillars, such as the salt marsh 

 caterpillar, army worms, the white-lined sphinx moth, and 

 grasshoppers multiply upon weeds growing in neglected fields 

 until they overflow and destroy crops. Many insects feed on 

 weeds during the early part of the s'eason or after the crop which 

 they injure is harvested, so that the destruction of these weeds 

 may often considerably shorten their breeding season or increase 

 their mortality. Thus the corn root-aphis lives on the roots 

 of smartweed and other weeds and grasses until corn is available, 

 and cutworms feed on whatever vegetation is found before a 

 crop is planted. In this connection " volunteer " plants should 

 be classed as weeds, as they frequently furnish food for insects 

 in the same way. Thus the cotton boll weevil feeds on volunteer 

 cotton in early spring and the Hessian fly on volunteer wheat 

 in late summer and early fall. Such useless trees as wild cherry 

 and seedling apple trees might also be considered as weeds, as they 

 harbor many of the insect pests of our orchards and should be 

 destroyed as far as possible. 



Fertilization and Culture. Although there is some evidence 

 that under some conditions, kainit, lime and nitrate of soda may 

 have some direct effect on insects, it is probable that their chief 

 importance is to so stimulate the plant that it will not be subject 

 to insect attack or will grow in spite of some injury. It is well 

 known that plants which have been weakened from any cause 

 whatsoever are much more subject to the attacks of insects and 

 diseases, and it is therefore obvious that plants which have had a 

 vigorous growth and which will mature rapidly will much better 

 withstand insect attack. Thorough preparation of the soil 

 before planting, liberal fertilization, and thorough culture are 

 most important in growing a crop in spite of its insect enemies. 

 In many cases liberal fertilization and culture will mature a good 

 crop where under poorer care it would have succumbed to insect 

 injury. In general, land covered with barnyard manure presents 

 more favorable conditions for the hibernation of insects than that 

 fertilized with mineral fertilizers, but unless this is very appreciably 



