31 
gram VI.),—now first brought out on this general diagram; and 
the more rapid decline of these two lines at their beginning than 
of the line for oats—more rapid than the ascent of that for wheat. 
The whole may be generalized to the effect that where chinch- 
bug injury is beginning merely, and is not yet very serious, it 
will be greater where wheat is more abundant and where oats, corn, 
and grass are less so—especially the latter two; but that as the 
insect damage gradually becomes overwhelming, the wheat area 
may be expected to diminish slowly with the heavier grades of 
loss, the area in oats increasing rapidly at the same time, and 
corn and grass likewise finally taking an upward turn. Otherwise 
stated, those districts in which most wheat is raised feel the dam¬ 
age first and most severely; those in which wheat and oats are 
the principal crops next receive the brunt of the insect attack; 
and the last to be seriously affected are those in which corn and 
grass are the leading products. 
In brief, the lines on these two diagrams illustrate, in the first 
part of their course,—that really representing Central Illinois, 
the normal relations of an at least fairly healthy agriculture; 
while in the last part they tell the sad tale of an increasingly 
deadly, an almost overwhelming, malady. The decline of the 
wheat line shows the ruin of wheat culture impending, if not 
almost accomplished in 1887; and the successive rise of the lines 
for the other crops shows from what sources the chinch bug was 
then drawing its principal support, and which crops it would next 
attack most heavily.* 
The rules of practice to be drawn from the foregoing conclu¬ 
sions are as follows: 1. Whatever may be done by cropping 
against the chinch bug must be done early or not at all. If action 
be delayed year after year until these insects become excessively 
numerous, the abandonment of wheat or other special crops will 
do no good, and, taken alone, may do great harm. In short, this 
is a preventive rather than a remedial measure. 2. In the begin¬ 
ning of an outbreak, the acreage in wheat, barley, and rye should 
be promptly reduced or those crops should be wholly abandoned. 
3. If the chinch bug continues to increase, the oats area should 
be rapidly diminished,—corn and grass remaining the principal de¬ 
pendence, and clover being substituted for the latter wherever 
practicable. 
* It may possibly be objected to this reasoning, that since the relation demonstrated between 
the highest grades of chinch bug injury and a peculiar distribution of the principal farm crops is 
one of coincidence only, it may be that the peculiar cropping is an effect of the chinch-bug injury 
but not in any sense a cause,—that, in other words, the farmers of the worst infested regions are 
attempting to protect themselves against the chinch bug by lessening the wheat area, and increas¬ 
ing that in oats first, and afterwards that in corn and grass. If this be so, we shall find, on eom- 
paring the areas of 1886 with those of 1887, that the oats acreage of 188. is not only larger than 
that for 1886, but that the ratio of increase is notably greater in those townships where chinch-bug 
damage is very high than in those where it is but moderate; and the same may be said of corn ana 
grass. A careful comparison of the crop reports from Southern Illinois for these two years shows 
no such relation. The area in all the crops is greater (as already remarked) in 188 < than in 18»b,— 
that is, the population is increasing and the woodlands are being cleared up; but the ratio oi in¬ 
crease for the above crops is not greater in the worst infested counties than in those less damaged. 
