CHAPTER XXXVI 

 INSECTS AFFECTING FIELD AND FORAGE CROPS 



As the great field crops of the United States are its chief wealth, 

 the insect pests that attack grains, cotton and grasses are the 

 most important animal enemies of our material welfare. The 

 annual losses from insect attacks on cereals amount to three 

 hundred million dollars, on hay and forage crops to sixty-six 

 million dollars and to cotton eighty-five million dollars. The 

 annual losses to wheat and corn caused by the attacks of but 

 two insects, the Hessian-fly and the chinch-bug, must amount 

 to a hundred million dollars. Too much time and care, 

 then, cannot be given to the study of the nature of the grain 

 pests and to devising means of lessening their ravages. Be- 

 cause of the enormous supply of food furnished them by our 

 great fields of growing grain, their numbers may become, 

 without restraint, almost inconceivable. In fact, in the case 

 of all the insect pests of fruits and crops it is our own fault, as 

 it were, that has led them to become as dangerous to these crops 

 as they are. We have, by our planting of great numbers of 

 one kind of plant together, furnished the insects such bountiful 

 supplies of food that their enormous increase in numbers is 

 an inevitable result. It is this encouraged increase that con- 

 stitutes the danger. The number of chinch-bug individuals 

 that can live at one time in a growing cornfield of hundreds of 

 acres is simply inconceivable. But as the increase of animals 

 proceeds by geometrical ratio while the addition of new acres 

 of food supply can increase only by arithmetical ratio, the 

 insect numbers finally become more than the food supply can 

 maintain without too much injury, and then the great losses 

 begin. 



The grain pests are of great variety of kind and habit. 

 Aphids, and beetle and moth larvae attack the roots. Biting 



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