36 THE CHINCH BUG. 
That the amount and frequency of rain during the month of May- 
has very much to do with the ravages of chinch bugs where sufficient 
numbers have wintered over to produce the requisite number of young, 
is further shown by the fact that in 1894 the only locality where serious 
ravages were committed was in Wyandot County, as shown on map 
(fig. 9), and this was one of the few areas in Ohio where the precipita- 
tion during that month was less than 3 inches. Except over a circular 
area covering less than one half of the county the amount of precipita- 
tion was 3 to 5 inches, and this area includes that ravaged by the chinch 
bugs during the following month. 
Still more striking, however, is the relation between the two phenomena 
during the following year. The last of this series of maps (fig. 10) shows 
the area over which chinch bugs were reported and the area where their 
injuries were the most severe; also, by horizontal lines, the areas over 
which the amount of precipitation was the least. From this it will be 
observed that in all of the seriously affected area, and in nearly all of the 
area over which the pest was reported at all, the precipitation during 
the mouth of May, 1895, was from 1 to 2 inches, the extension of the 
point westward into Shelby County being especially interesting. It 
may be said with regard to the occurrences outside of this area of light 
precipitation that the exact localities were probably not indicated, as 
the information was secured from farmers, and their locations as indi- 
cated on the map were their post-office addresses, which might have 
been several miles away in any direction, and the isolated points of 
attack were often based upon one or two reports. If exact localities 
could have been obtained, and the precise area of precipitation indi- 
cated, the connection between the two phenomena would have been 
shown more correctly, and would probably have revealed even a greater 
uniformity than is now apparent. It must be understood, however, that 
in these calculations extreme northeastern Ohio is excluded, and I 
believe that what is true of the balauce of the State will be found to be 
equally correct as regarding territory occupying the same latitude west- 
ward to the limit of this area of distribution. While it is probable that 
the effect of precipitation during August would have a similar influence 
on the second brood of young, and, consequently, upon the number of 
adults which would go into winter quarters, yet a careful study of the 
two factors shows that meteorological conditions in August have a far 
less influence upou the following brood than do those of May. 
Owing to causes which are as yet unknown to me the same laws do 
not apply to the northeastern part of Ohio and to what I have termed 
the westbound tide of migration. Here and as against the more or 
less short-winged form of chinch bug, meteorological conditions appear 
to exert a far less potent influence. What is true of meteorological 
conditions during May elsewhere in Ohio, seem to be partly true of 
June in the northeastern portion of the State, though there is not the 
evidence of the effect of precipitation here that we have elsewhere. 
