19 



DAMAGE TO SMALL GRAIN AS COMPARED WITH THE AREA IN WHEAT 



AND OTHER CROPS. 



Perhaps the most difficult, and certainly the most interesting, 

 significant, and conclusive part of this discussion relates to the in- 

 fluence of wheat culture on damage to wheat itself and to oats bj 

 the first brood of the bugs, under the two widely contrasted sets 

 of conditions found in Central and Southern Illinois respectively, 

 in 1887. Certainly if it shall appear that the ratio of damage to these 

 crops increased with increase in the areas of the crops themselves, — if, 

 'in other words, the first brood of the chinch-bug destroyed a larger 

 percentage of these grains the larger was the surface covered by 

 them, — we cannot possibly avoid the conclusion that wheat cul- 

 ture has a powerful effect on chinch-bug injury. If, further, we 

 shall discover here the same contrast between Southern Illinois 

 and the other parts of the State as has appeared in previous dis- 

 cussions, we shall be confirmed in the opinion that a measure 

 like the reduction of wheat culture, which may promise the best 

 results when early applied, may wholly lose its efficacy, and possi- 

 bly even become a source of mischief, if postponed too long. 



Table IX. 



Central Illinois, 397 Towns. Injury to Small Grain, 1887, com- 

 pared with Crop Areas for the Same Year. 



Degree of Injury. 



No. 

 of Tps. 



Wheat. 



Barley. 



Rye. 



Oati- 



Corn. 



None 



Little 



Moderate 



Considerable 



Great 



Very Great.. 



271 

 79 

 28 

 15 

 1 

 3 



1,559 

 1,984 

 2, 436 

 2,331 

 901 

 2, 668 



2, 581 

 2,467 

 1,456 

 1,828 

 931 

 2,251 



5,579 

 5,135 

 3,412 

 3,551 

 1,532 

 5,461 



Taking up first the table for Central Illinois, we see at once a 

 decided ascent from 1,559 acres of wheat per township where 

 wheat and oats were uninjured, to 2,321 acres where these grains 

 were considerably damaged. That it is the increase in wheat that 

 is to be connected with this greater loss, and not tlio deciease in 

 acreage of oats (from 2,58 i to 1,828) is shown by combining the- 

 wheat and oats areas for each grade of injury, giving 4,140 for the 

 first term of the series and 4,1'19 for the last, the intermediate 

 numbers being one above and one below the average. Otherwise- 

 stated, wheat and oats have suffered more severely, in Central 

 Illinois, as the wheat area increased while the joint areas of both 

 grains remained unchanged, whence we can only conclude consist- 

 ently with the known preference of the chinch bug for wheat that 

 it is the wheat increase which has caused the greater loss. We 

 notice, further, that the acreage of grass shows neither marked 

 increase nor decline; while tliat ,of corn falls off some 35 per cent, — 

 the latter fact to be explaijied, as noticed elsewhere, by the rela- 

 tively little attention given to corn in the broken regions es- 

 pecially adapted to wheat farming. 



