85 



well distributed as to furnish abundant pasturage to the adult bugs 

 when they scatter abroad from their winter quarters, and to the young 

 of the first generation hatching in the field to which their parents have 

 been drawn for food. 



By an examination of the records of the U. S. Weather Bureau and 

 the data of crop production in southern Illinois for 1907, 1908, and 

 1909, as published by the State Department of Agriculture, I am led 

 to the conclusion that an immediate cause of the beginning of the 

 Washington county outbreak was the warm weather of the spring and 

 summer of 1908 and 1909 and the character of the farm crops pre- 

 dominating in the country where the trouble began. 



The U. S. Weather Bureau stations nearest the fields in which the 

 chinch-bug was first noticed in 1909 were those at Tilden and Sparta, 

 in the northeastern part of Randolph county, the first close to the 

 southwest corner of Washington county and the second about six 

 miles farther south. The weather records were taken at Tilden up to 

 1909 and at Sparta thereafter. The average temperature and rainfall 

 data here for the four months from May to August inclusive are given 

 in the following table. The minus sign before a number indicates de- 

 grees of temperature or inches of rainfall below the normal for the sta- 

 tion, and a plus sign indicates degrees or inches above the normal. 



Total Departures from Normal Temperature and Rainfall, May to August, 

 1907-1911, Randolph Co., III. 



Year 



Temperature 



Rain 



Remarks 



1907 



— 5.4 



+3.47 



Cool and wet 



1908 



+ 5.1 



+3.17 



Warm and wet 



1909 



+ 4.2 



—0.26 



Warm and normal 



1910 



—10.1 



+3.24 



Very cool and wet 



1911 



-flO.4 



—6.13 



Very warm and very dry 



It will be seen that 1907 w T as a year unfavorable to chinch-bug in- 

 crease, being both cool and w r et, altho the change to warmer weather 

 began in midsummer of that year, July and August averaging 1.5 de- 

 grees above the normal. 1908 opened with an early spring, the mean 

 temperature of March being 6.8 degrees above the normal, and it con- 

 tinued warm until October, except for a drop to normal temperature 

 in June and July. In 1909, June and August were warm in Kan- 

 dolph county, the excess temperature of August especially rising to 

 a mean of 4.2 degrees. This, with a shortage of 3.12 inches in the 

 rainfall of that month, when young chinch-bugs of the second genera- 

 tion were hatching in the corn, seems to have -been the match which 

 set off the explosion, for it was in the corn fields of that fall that the 

 chinch-bug was first noticed in extraordinary abundance. The fol- 

 lowing spring it reached numbers to do considerable injury to wheat, 

 and later in the season to corn also, in at least nine counties, as al- 

 ready reported. The extent and amount of injury by ehinch-buga 



