14 BULLETIN 1103, U. S. DEPARTME:N'T OF AGEICULTUEE. 



In Iowa this insect appeared for the first time in 20 years in 

 the south-central part in Decatur County. 



The northern limit of the outbreak was the southern tier of coun- 

 ties in Michigan, including the greater part of Lenawee and Hills- 

 dale Counties, and the southern part of Branch, St. Joseph, and 

 Monroe Counties. As far as the records of the station go, this out- 

 break is the first that has occurred in Michigan since 1887. 



An isolated outbreak of minor importance appeared in South 

 Dakota in the southeastern part covering Bon Homme and Charles 

 Mix Counties. This was the first outbreak during at least the past 

 12 years. 



In Texas the only report of serious damage was received from Hill 

 County. The pest occurred in normal numbers, however, over the 

 region usually infested. 



The temperature over the whole infested territory was above nor- 

 mal during the early fall of 1920. November, however, had an 

 average deficiency of 1.8°, the deficiency being greatest in Missouri, 

 Kansas, and Oklahoma where it was between 3° and 5°. The winter 

 of 1920-21 was unusually warm, the average departures during 

 January, February, and March being over 7° F. The spring and 

 summer were also warmer than usual. (See Fig. 3 and Table 2.) 



The rainfall over this region was about normal during the fall and 

 winter, being generally below normal during the winter months. 

 In March wet weather set in, the average being over an inch above 

 normal during this month. April was also above normal, while 

 May was quite dry throughout the entire region, the deficiency be- 

 ing 1:1 inches. June and July were dry throughout most of the 

 region, although there were heavy rains in June in Oklahoma and 

 Texas, where the excess was between 3 and 4 inches, bringing the 

 average for the region above the normal. August and September 

 were generally wet, September having an excess of precipitation 

 of 1.69 inches. The dry periods in May and July were advan- 

 tageous to the development of young chinch bugs while the wet 

 weather of August and September undoubtedly did much to reduce 

 the infestations of the fall brood over much of the infested region. 



The accompanying map (Fig. 2) indicates the areas generally 

 infested in 1921 (shaded), the area of most serious damage in 1921 

 (black), and the line limiting the western known distribution of the 

 pest. The black dots are isolated reports, from literature, beyond 

 this western limit of distribution. 



