124 MISCELLANEOUS PAPERS. 



and economic control have been obtained by him or under his super- 

 vision. '\¥lien he began the study of this aphis, it was believed to 

 be merely the root form of the corn leaf-aphis. Failing after many 

 elaborate experiments to breed either from the other, and repeatedly 

 tracing the complete life history of the root-aphis year after year 

 with no appearance of the leaf-aphis at any time in the series, he 

 regarded the corn root-aphis as a distinct species, and described it as 

 such in 1891, in the Seventeenth Report of the State Entomologist 

 of Illinois. 



The insect has, of late years, become of great economic importance, 

 not only in Illinois, but also in many other States of the corn belt. 

 Outside of Illinois it has been reported as injuring corn in New York, 

 New Jersey, Maryland, Virginia, West Virginia, Ohio, Indiana, Min- 

 nesota, Iowa, Missouri, Nebraska, Kentucky, Mississippi, Louisiana, 

 and Colorado. 



FOOD PLANTS." 



Although corn is its principal food plant, the corn root-aphis 

 attacks also sorghum and broom corn ; has been reported as attacking 

 the roots of squash vines in Delaware and Ohio, and what is at pres- 

 ent considered as this species has been found on the roots of numerous 

 weeds and grasses, namely, smartweed {Polygonum incarnatum), 

 knotweed (P. persicana),crah grass {Panic um) , piirslsiue {Portulaca 

 oleracea), dock {Rumex crispus and R. aUksimus), Setaria glauca, 

 S. vindis, S. germanica, fleabane {Eiigeron ccmadense), mustard 

 {Brassica nigra) ^ sorrel {Oxalis stricta), plantain {Plan f ago major 

 and P. 7'ugelUi), pigweed {Amarantiis hghndus), and ragweed 

 {Amhrosia triflda). In May, 1907, Mr. E. O. G. Kelly found it on 

 wheat roots in a field which had been in corn the previous year. It 

 has also been collected on the roots of cultivated aster, upon which I 

 have found it to be of much economic importance in Illinois. 



LIFE HISTORY. 



Last year (1906) I obtained the complete life history of this corn 

 root-aphis froln the G:gg stage in spring to the egg in autumn. The 

 vivaria which I used for the rearing and observation of this root 

 aphis consisted of 8-dram or 10-dram glass vials, each containing a 

 ball of moist cotton in the bottom and plugged at the top with a piece 

 of cotton. In this cage a sprouting corn plant was placed, a reserve 

 supply of these food plants being constantly kept for use. The first 

 young and the last young of each generation were placed on corn roots 

 in separate vials, and these vials were kept in closed boxes to exclude 



a The scieutific names of plants throughout this paper are given according to 

 the nomenclature of Gray, in deference to the author's wishes. — Ed, 



