59 
weather are greatest in the southern portion of the State. But the dif- 
ference between this weather condition is certainly not so marked be- 
tween Tippecanoe and Benton Counties on the one hand, and La Porte 
and Lagrange Counties on the other, as to result in a difference in the 
number of bugs amounting to that between a great abundance and 
almost none at all. In Tables E, F, and G are given the mean tempera- 
ture and rain-fall for the months during which these elements most 
affect the Chinch Bug, and extending over a period of five years.* Thisis 
as far back as the Indiana records extend. The records from Princeton, 
Ind., indicate the meterological conditions during this period in the bug 
infested area, and those from Angola are a like record of the weather 
conditions in the region exempt from Chinch Bug attack, while Table G 
gives the meterological conditions in De Kalb County, northern Illinois, 
where Chinch Bugs have been abundantsince 1855, formerly doing serious 
damage to spring wheat, and have, since about 1862 (wheat of any sort 
being no longer grown to any extent), been transferring their attention 
to the corn crop, but being at present less abundant than in south- 
eastern Indiana or southern Illinois. 
From a study of the tables given it will be seen that while the 
northern Illinois locality had a less rain-fall during the spring and early 
summer than the northern portion of Indiana, it also had a less amount 
than had southern Indiana; yet, while Chinch Bugs are more numerous 
in the Ulinois section than in northern Indiana, they are not so abund- 
ant as in southern Indiana. 
Geologically, the northern portion of Indiana differs from the south- 
eastern portion, the former being Devonian and the latter carbonifer- 
ous or subcarboniferous. This, however, could have little effect on the 
Chinch Bug, except, possibly, so far as it influenced the natural flora, 
especially the grasses. Prof. James Troop, who has made the grasses 
of Indiana a study, informs me that the following are all, or nearly all, 
the species found in the southern portion of the State which do not 
occur in the northern portion: Uniola latifolia, Arundinaria tecta, Pas- 
palum fluitans, P. eve, Panicum prolificum, P. anceps, P. vicidum, Andro- 
pogon divisitiflorus. 
From the foregoing it will be seen that to no one of these elements 
alone, as existing between southwestern Indiana and Illinois on the 
one hand, and northeastern Indiana, southern Michigan, and northern 
Ohio on the other, can this immunity from Chinch Bugs in these last 
localities be traced. Whether the combination of two of these elements, 
such as dry weather and wheat-growing, is to be held wholly responsi- 
ble, or whether there is still another potent element, as yet unknown 
to us, which, either in itself or combined with some other, is the prime 
cause of the present state of affairs, only future studies can demonstrate. 
* Kindly supplied me by N. E, Ballou, M. D., Ph. D., Sandwich, I1., for thirty years 
volunteer signal observer at that place.—I’. M. W. 
