CONTRIBUTIONS ON THE CORN ROOT-APHIS. 



99 



and published in the American Farmer , a mentioned " a species of 

 louse or aphis, that infests grounds and feeds upon the roots of 

 wheat, corn, young trees, etc., and do immense damage." And Thos. 

 W. Emory, 6 in writing of sedge in wheat, said : 



I believe that this insect is the same as that known by the name of root 

 louse in corn, so frequently found in that plant, growing after clover, when 

 the land is early flushed, and which occasions so stinted and diseased a 

 growth that it rarely recovers till late in the summer, and not then if the 

 season is dry. c 



Mr. Emory gave his address as Poplar Grove, without mentioning 

 the State. But although the State was not mentioned, his writings 

 give the impression that he was talking about conditions in Maryland. 

 From these two notices it appears 

 that the corn root-aphis was 

 familiar to the people of Pennsyl- 

 vania and Maryland as early as 

 1822, because there is no other 

 aphis on the roots of corn common 

 enough to have been so generally 

 known. 



In Illinois the corn root-aphis 

 was first studied in 1862 by B. D. 

 Walsh near Rock Island, where it 

 had attacked a small field of corn 

 and destroyed about half of it. 

 Walsh collected specimens from 

 which he reared winged females 

 (fig. 55), and from the similarity 

 of these to the corn leaf-aphis he 

 decided that they were identical, 

 and in an essay published in the 

 Transactions of the Illinois Agricultural Society he considered the 

 leaf-aphis to be but an aerial form of the root-aphis. This view was 

 accepted by Cyrus Thomas and later writers who studied the species. 



Dr. S. A. Forbes began his study of this insect in 1883, and, as 

 a result of his work and the work of his assistants, came to the con- 

 clusion that the root-aphis is a distinct species. So he described 

 it as such under the name of Aphis maidi-radicis. d His studies of 



Fig. 54. — The corn root-aphis (Aphis 

 maidi-radicis) : Wingless, viviparous fe- 

 male, greatly enlarged, and antenna, 

 highly magnified. (From Webster.) 



a American Farmer, vol. 4, p. 395, March 7, 1823. 



6 Idem, p. 71, May 24, 1822. 



c Webster, F. M.— Early published references to some of our injurious in- 

 sects. Insect Life, U. S. Dept. Agr., Washington, D. C, vol. 2, Nos. 7 and 8 

 p. 264, 1890. 



d Seventeenth Report of the State Entomologist of Illinois for 1889 and 1890. 

 Trans. Dept. Agr. 111., Springfield, vol. 28, pp. 64-70, colored plate " B," figs. 

 1-4, 1891. 



