55 



year in places where they were the year before the most abun- 

 dant, and an increase in places where they were then less numer- 

 ous. This territorial propagation outward from a center of first 

 excess, accompanied by a diminution in numbers in the principal 

 area of origin, has been fully described above; and a similar prop- 

 agation from districts where the crop most preferred and first in- 

 fested (wheat) is most abundant, to adjacent districts where the 

 leading crops are those freely fed upon but less preferred, (oats, 

 grass, etc.), is also highly probable, but less easily demonstrated. 

 In both cases the diminution in numbers is doubtless largely due 

 to the direct and indirect consequences of over-crowding, — a condi- 

 tion which always arouses or intensifies the action of the natural 

 checks on excessive increase. 



Further comparison of the crop areas of 1886 with the injuries 

 of 1887 shows that a very decided diminution of the corn area 

 has had little or no effect to diminish the loss to small grain the 

 following year. 



From the above we learn that the proper procedure respecting 

 the grass and the cereal crops in the presence of a chinch-bug 

 uprising is the prompt and early abandonment of wheat or a de- 

 <;ided limitation of its area, to be followed presently, if the attack 

 continues, by a diminution of the oats acreage also, and the sow- 

 ing of clover, whenever practicable, instead of the grass forage 

 plants. We also find that these measures must be taken early or 

 not at all, since if too long postponed they may easily do more 

 harm than good. 



An analysis of the published opinions of economic entomologists 

 shows a general and rather indiscriminate dependence on the 

 abandonment of wheat culture as a defence against the chinch 

 bug, this opinion being more positive, however, among the older 

 entomologists than among those who have studied the question 

 recently. It is a pleasure to find that the foregoing elaborate 

 study necessitates little amendment of the recent statements and 

 recommendations made from this office. A similar indiscriminate, 

 but not unanimous, opinion as to the advantage of the abandon- 

 ment of wheat appears in the statements of 200 agricultural cor- 

 respondents of the office, 87 per cent, of the replies to an inquiry 

 touching this matter being in the affirmative. 



From the miscellaneous experiments here reported, it appears 

 that the worst infested fields of small grain may be sustained 

 under a chinch bug attack by heavy fertilization, if the land be 

 originally in good condition ; and that, in general, the damage done 

 will vary inversely to the fertility of the soil and the support 

 given by fertilizers to the crop attacked. The best fertilizers for 

 this purpose on the wheat lands of the central part of Southern 

 Illinois, seem to be, first, barn-yard manure, and, second, the 

 phosphates and nitrates combined. 



The kerosene emulsion, whose deadly effect on the chinch bug 

 was first shown by me in 1882, has repeatedly proven a very valu- 

 able agent in the hands of farmers when applied in the field for 



