56 
consequently, when two such seasons prevail generally over the 
Northwest both species are apt to appear, as was the case in 1874. 
But the case is different with the Army-worm. This requires a dry 
Summer and Fall and, I am inclined to believe, also a dry Winter, 
followed by a cool and rather damp and cloudy Spring. The two 
most noted years of its appearance in this State were 1861 and 1875, 
each of which followed a preceding dry year, but in neither case was 
the year in which it appeared warm, 1861 being one of average tem¬ 
perature, and 1875 rather cold. The latter, which is the only one 
for which we have the records of the different seasons, was more 
than usually damp in the Spring and Summer. 
While on the subject of meteorology, we present here, not as hav¬ 
ing any direct connection with entomology, but simply as bringing- 
out some points of interest to the farmers of Illinois, and as bearing 
on the subject of meteorology, curved lines, showing the relation 
between the rainfall and the yield of wheat and.corn, and the price 
of these commodities. 
The upper dark curved or zigzag line indicates the rainfall for 
the years 1861 to 1877. The middle series, consisting of two lines, 
showing the yield and price of wheat, the solid dark line the aver¬ 
age yield per acre, and the (red) dotted line the average price per 
bushel.* 
The lower series shows the yield and price of corn; the solid line 
the yield, and the dotted line the price. 
A comparison of the yield per acre of these grains with the rain¬ 
fall shows very clearly that the wheat crop is less affected by the 
variation in the amount of rain than corn; the four years of greatest 
wheat yield are 1864, 1866, 1878 and 1877—the first was dry, 1866 
was about an average year, 1878 was dry, and 1877 a little above 
the average. The small yield in 1867 corresponds with the great 
drought of that year, but the smallest yield was in 1876 when the 
rainfall was excessive. 
The years of the series in which the yield of corn was about 34 
bushels per acre are 1861, 1862, 1865, 1868, 1870, 1871, 1872, and 
1875. Of these years the rainfall was below the average in 1861, 
1870, 1871 and 1875—was about it in 1872, 1864, 1868 and 1872. 
The smallest yield was in the excessively dry and great Chinch-bug 
year, 1874; in the years 1863 and 1873 the yield was very small 
and these were dry years. 1869 and 1876 were excessively wet, and 
the yield was small, not exceeding an average of 25 bushels to the 
acre. The yield as given for 1871, I am inclined to think, is not 
reliable, the. census returns having evidently affected the statistics 
of the Agricultural Department of the General Government, which 
we have followed. 
The comparison of yield with prices is also worthy of attention, 
as it brings plainly to view a fact that is of importance to our 
farmers and grain buyers. 
A slight glance at the wheat series is sufficient to show that the 
price is not governed by the yield; in 1864 the yield was large and 
the price also above $1.50; in lb65 the yield was only 11 bushels 
and the price only $1.09. In 1874, when the yield was but 11J 
bushels, the price was only 60 cents. This indicates what we know 
to be true, that the yield in Illinois does not govern the price; but 
* Cut not obtained in time. The reader can easily draw curves by the data given. 
