231 
clearly the hibernation of bugs directly adjacent to the lields they infest 
later. The fact that certain fields almost identical in conditions where 
stubble, corn stalks, and other rubbish were burned, were very free from 
bugs, while others not burned were badly infested this season, is strong 
confirmation of this view. 
In about 90 per cent of the infested fields examined the ground was 
high and in all cases had been extremely dry during the preceding fall 
and spring. In about SO per cent the fields were hilly and ridged, and 
in most cases the damage was first apparent upon the higher portions 
of the fields, the exceptions to this rule being in the case of fields 
which had evidently become infested from bugs hibernating in slough 
grass or weeds occurring in lower places, and it must be noted here 
that even these places were comparatively dry during the twe4ve 
months preceding the damage of the present season. The character 
of the soil does not seem to have been of so much importance in deter- 
mining the distribution, as we find a nearly equal distribution of cases 
between black loam, clay loam, and sandy soils; but on the whole the 
soils most infested were rather light and friable soils, even the clay 
soils, where abundant, being of a rather light and in some cases sandy 
character. As to the distribution in the State with reference to crop 
distribution, the counties most infested are those in which there has 
been a pretty continuous growth of small grains — wheat, rye, and 
barley — but, as will be seen by comparing the chinch-bug distribution 
with crops by the annexed tables, the distribution, instead of being for 
those counties where spring wheat was the special crop, are those in 
which fall wheat or rye constitutes the special grain crops. 
The infested area runs across various geological formations from Silu- 
rian to Carboniferous, and clearly bears no reference to soils in this 
regard; but from the fact that this area is in large part covered with 
glacial deposit the geological horizon is of little consequence. 
It may be noted that the principal centers of injury are the divides 
and bluffy sections adjacent to the river valleys of the Des Moines, 
Skunk, Iowa, Cedar, and Wapsipinicon rivers and also along the Mis. 
sissippi. 
It will be noticed that practically all the damage occurring in the 
southeast quarter of the State and reference to the table of crop sta- 
tistics will show that the counties Decatur, Wayne, Appanoose, Monroe, 
Mahaska, Keokuk, JerTerson, Henry, Des Moines, Van Buren, Lee, 
Louisa, and Muscatine are the most important fall-wheat districts, 
while for spring wheat and barley the northwest counties of the State, 
especially Kossuth, Emmet, Dickinson, Osceola, Lyon, Sioux, O'Brien, 
Clay, Palo Alto, Plymouth, Cherokee, Buena Vista, and some others are 
the important spring- wheat districts, and in none of these were chinch 
bugs present in sufficient numbers so that they were reported. It would 
seem, therefore, that the popular idea that chinch bugs affect spring 
wheat rather than fall wheat is due to the fact that their injuries arc 
