12 



BULLETIN 1103, U. S. DEPARTMENT OF AGRICULTURE. 



northeasterly direction, from the north-central part of Texas, across 

 the center of Oklahoma, eastern Kansas, most of Missouri, southern 

 Illinois, central Indiana, into the northwestern corner of Ohio and 

 the southern tier of counties in Michigan, 



The very seriously infested area (Fig. 2) was confined almost exclu- 

 sively to Indiana, Illinois, and Missouri. In Indiana the pest has been 

 steadily on the increase in destructive abundance since 1917. In 1917 

 very few chinch-bug cases were reported to the station; reports in 

 numbers started to come in during the season of 1918, were almost 





-J.2 



-0.6 \ 

 '0.4- \ 

 -a2 \ 



-l+/.2 

 +/<5 



_J -3./5> 



u I H U O n 0° 



/Bso /sa/ 



Fig. 3. — Monthly departures from normal temperature (solid black) and rainfall (white) 

 for the fall of 1920, the winter of 1920-21, and the growing season of 1921 in the 

 region infested by the chinch bug during 1921. (See also Table 2.) 



doubled during 1919, and quadrupled in 1920. During 1921, 52 coun- 

 ties were infested. The northern limit of the infested area in Indiana 

 extended from the north-central part of Steuben County almost di- 

 rectly southwestward to the southern border of Warren County, 

 while the southern limit extended from the center of Union County, 

 through the southeastern corner of Morgan County, to the southeast- 

 ern corner of Posey County. The area of severe infestation ran 

 parallel to these two lines, running on the north from the center of 

 DeKalb County to the southern part of Vermillion County, and on 



