"i6 



part of the State, where the wheat acreage was large and the in- 

 jury very severe, dominates the lower part of the table, the groups 

 of townships representing the three higher grades of injury, being 

 mostly in that section ;* while the upper part of this general table 

 is little but a copy of the corresponding part of that for Central 

 Illinois, the averages drawn from the relatively large wheat acre- 

 age there being little affected by the very small wheat acreage of 

 the northern district. Table lY. is, therefore, less an average of 

 the others than a summary recapitulation of their teaching. The 

 descending series presented by the six upper figures of the columns 

 for rye, oats, corn, and grass remind us that a diminishing area 

 of these crops goes with the increasing wheat areas of the first 

 column, but that the decrease of the former is insignificant in 

 comparison with the rate of increase of the latter ;t while the 

 regular rise in the lower numbers in each column simply expresses 

 anew the fact that where the chinch bug has been long enough 

 abundant to practically occupy the country, it will multiply accord- 

 ing to the area in any and all crops capable of affording it food. 

 In other words, these tables show us that corn suffered worst, as 

 a rule, in 1887, in those counties and townships where wheat was 

 most abundant, and that a regular gradation of injury to corn by 

 the chinch bug may be made out corresponding to the gradation 

 in the wheat acreage; and, further, we learn that where the chinch 

 bug became very numerous, the other great grass crops, — that is, 

 the other small grains, corn, and the grass forage plants, — began to 

 suffer heavily, to breed the first generation of the bugs, and so to 

 encourage their increase and the consequent damage to corn — oats 

 being the first to take this turn, and corn and grass the next. 



From these tables we may draw, then, this provisional practical 

 conclusion, to be tested by the remaining tables of the series, 

 that a limitation or abandonment of wheat culture may he ex- 

 pected to serve as a preventive measure at the beginning of a 

 chinch-bug outbreak but that it cannot be depended on as a 

 remedy when such an outbreak is fully developed. 



INJURY TO GRASS AS COMPARED WITH AREAS IN WHEAT AND OTHER 



CROPS. 



Meadows and pastures are often invaded by chinch bugs escap- 

 ing from ripening grain; and where the drouth is so severe as to 

 destroy the corn in summer, the second generation may be bred 

 to some extent in grass. It also occasionally happens that if 

 nothing else offers as food for the hibernating generation, young 

 meadows tempt them in spring to settle, and lay tlieir eggs and 

 there rear tlieir young as in fields of wheat. A study of the rela- 

 tion of wheat culture to injury to grass will therefore have its special 



*Itwill bp nocn (Tablft I.) that 1B3 of tho 179 towns rojiortins: an injury to corn highor tlmn 

 "groat" are in Soutlinrn IllinoiH, and only 2(5 from C(Mitral and Nortliern Illinoin (Tables II. and III.) 



tThiH rfilation of tho cron aroas in Contral lilinole Is doubtless dno to the fact that much of the 

 whoat of tho roi^lon Ib ralnod in districts not as well adapted to any other crop,— the broken clay 

 lands, originally wooded, along tho stroamB. 



