10 



JS^Tables of this description were made for each year (1886 and 

 1887) and for each crop in each of the areas above mentioned, the 

 whole being finally summarized and concluded by a general table 

 setting forth the facts for the whole State, and for all the crops 

 taken together. 



GENERAL REMARKS UPON THE TABLES. 



Before entering upon a detailed examination of these tables, a 

 few critical and explanatory remarks may well be made. 



In the first place, as the data here set forth relate to only one 

 of a considerable number of varying conditions which must affect 

 the multiplication of the chinch bug and its consequent damage 

 to crops, it is not to be expected that any correspondence appar- 

 ent between wheat culture and chinch-bug injury will be always 

 <;lear and uniform. As it is impossible that conditions of weather, 

 general average of soil, methods of cropping and farm manage- 

 ment, and the like, should be the same for all the groups of 

 townships, these and various other influences must have had their 

 various effects on the number and condition of the chinch bugs in 

 each case, so that a certain amount of variation, upward and down- 

 ward, will appear in the various series, really due to these con- 

 cealed but ever present differences of circumstance. 



Where the wheat acreage is very small and the chinch -bug dam- 

 age light, as in Northern Illinois, these miscellaneous and acci- 

 dental variations may completely conceal the slight variations to 

 be attributed to the insignificant differences in the amount of 

 wheat. 



Secondly, although the tcwnship assessors are doubtless, on the 

 whole, the class of men most likely to judge intelligently and 

 accurately concerning the damage done in their townships, this is 

 really a difficult matter to estimate, particularly as my questions 

 were not put to them until after they had made their annual 

 round. The judgment of different men must consequently some- 

 times have differed widely with respect to like conditions and 

 grades of injury. The meaning attached to the terms used in ex- 

 pressing their estimates of injury must also doubtless have varied 

 considerably, — although less, as I judged, than if 1 had asked men 

 not accustomed to think in ratios to give their opinions in the 

 form of percentages of injury. Other variations without significance 

 must have resulted from the fact that in all this investigation the 

 township has necessarily been taken as an unvarying agricultural 

 unit, — of uniform size, and with always the same ratios of culti- 

 vated and uncultivated lands. 



Tlio more or less serious errors thus arising are all, however, of 

 a sort to decrease rapidly with the accumulation of instances, 

 being most apparent in tlu^ tables of the smaller sections and 

 chiefly obliterated in the final tables for the larger sections and 

 for the entire State. Tn the concluding diagram it seems to me 



