Vol. Xxi] ENTOMOLOGICAL NEWS. 245 



Aphis aquaticus Jackson vs. Rhopalosiphum nym- 



phaeae Linnaeus. 



By JOHN J. DAVIS, Office of the State Entomologist, 



Urbana, 111. 



In the January, 1907, number of the "Ohio Naturalist," Mr. 

 C. F. Jackson describes as new a species of Aphis under the 

 name A. aquations. Mr. Jackson has very kindly sent me 

 specimens of his new species, and, comparing them with 

 aphids which I have collected on water plants in Illinois, find 

 the two identical. Also it agrees reasonably well with the 

 various descriptions of Rhopalosiphum nympaeae Linn. 



R. nymphaeae, an European species, was first determined as 

 such from specimens collected in this country, by Mr. J. T. 

 Monell, and was first reported by Messrs. Osburn and Sir- 

 rine* as occurring in Iowa on Nymphaea odorata (pond lily), 

 and probably the same species on Sagittaria variabilis. Later 

 Mr. J. H. Cowent mentioned R. nymphaeae (?) from Colo- 

 rado on Sagittaria varibilis. In 1905, Professor Theo. D. A. 

 Cockerell$ gave a detailed description of this aphid which he 

 collected in Colorado on Myriophyllum verticillatnm. Mr. 

 Monell writes me that he has found it in Southern Missouri 

 on native Sagittaria and in the public parks of St. Louis on 

 exotic water lily and other water plants. In Illinois we have 

 taken it on Sagittaria, Lcmna, and pickerel grass, out-of- 

 doors, and on Philotria canadcnse and calla, on which it often 

 becomes quite troublesome, in conservatories. 



As stated above, I have compared the American specimens 

 with the descriptions of Rhopalosiphum nymphaeae Linn., 

 given by Kaltenbach, Koch and Buchton, and find no appre- 

 ciable difference. In addition, I have made a careful com- 



*Notes on Aphididac. (Proc. Iowa Acad. Sciences f. 1892, vol. I., 

 pt. 3, p. 98. Also Insect Life, Vol. 5, Apr. 1893, p. 236. 



f A preliminary list of the Hemiptera of Colorado (Bull. Agr. Exp. 

 Sta., Colo. Tech. Ser. i, 1895, p. 123. 



t A lactustrine aphid ^Rhopalosiphum nymphaeae.) (Science, Vol. 

 22, Dec. 8, 1905, p. 764. 



