•284 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 4 



as the case happened to be, still were rapidly dying out and these 

 showed great numbers of large plump aphids clustered about the lower 

 stem and roots, draining the plant sap. These aphids were mostly 

 Geoica squamosa and, less commonly, Forda occidentalis, both of which 

 have previously been recorded as minor corn pests in Illinois. Dodge, 

 Adams and Seward counties showed particularly obvious injury, and 

 the injured fields were not concentrated, but were scattered through- 

 out the whole affected region, being often several miles apart, with the 

 intervening fields not noticeably affected by either the Geoica or the 

 Forda, though Siphocoryne avence was commonly present in small 

 numbers in all the fields. Taken as a whole the injury was rather 

 extensive. It first became apparent in September when small patches 

 began dying out, and these enlarged as the fall advanced and the aphids 

 multiplied and spread, until they involved an acre or two in extent, 

 and, not rarely, the entire field. The wheat in the affected patches 

 was cleanly taken and the plants were dead to the roots. The aphids 

 continued working until late in November undergoing some quite 

 severe temperatures. Almost invariably both these wheat-root aphids 

 are attended by the ant Lasius niger neoniger. We found the Forda 

 during the past winter hibernating abundantly under stones near nests 

 of the Lasius and feeding upon the heavy creeping rootstocks of a grass 

 presumably quack grass (Agropyron repens), at Lincoln. 



The present season has not been the first that these aphids have 

 injured wheat, though it is by far the most extensive injury we have 

 known. Our first definite knowledge of the injurious habits of these 

 aphids was recorded in 1907, when during April of that year Mr. H. 

 S. Smith found the Forda very abundant in the wheat fields of Buffalo, 

 Kearney and Adams counties while he was investigating reported 

 occurrences of the green, bug in that region. Although some plants 

 supported as high as forty aphids, the infested fields on the whole were 

 not seriously injured. In the fall of that year, October 17, Mr. Smith 

 found the Geoica attacking volunteer wheat scattered through the 

 sowed grain in Hamilton County, it being quite abundant upon the 

 roots and causing the plants to assume a sickly yellowish green color. 

 In 1908 the Geoica appeared in excessive numbers in Clay County 

 during middle October, one farmer reporting them to be present by 

 the milHons in his wheat fields. Last year (1909) the Forda injured 

 fields in several localities in Hall County, killing out the wheat in 

 patches an acre or two in extent between middle September and latter 

 November, and similar reports were received from Boone County in 

 October. The present season the Geoica greatly predominated, being 

 first found in Hamilton County in July, in limited numbers on corn 

 roots with Aphis maidi-radicis and abundantly on the grasses in the 



