4 BULLETIN 276, IT. S. DEPARTMENT OF AGRICULTURE. 



the interpretations of Cholodkovsky, Mordwilko, and Theobald that 

 species heretofore considered as synonomous with pisi, namely gei 

 Koch, uhnariae Schr., and ononis Koch, are good and distinct species 

 and that onobrycliis B. de Fonsc. is still a doubtful species. 



Our own results published herein assure us of the identity of the 

 pea aphis (pisi Kalt.) occurring in America and Europe. In America 

 there seem to be only two names, originating here, which can properly 

 be considered synonyms of pisi Kalt., namely destructor Johnson and 

 trifolii Pergande. 



The synonymy of Macrosiphum pisi Kaltenbach, as we now under- 

 stand it, is as follows: 



Macrosiphum pisi (Kaltenbach). 



Aphis pisum Harris. 



Aphis lathyri Mosley. 



Aphis onobrychis B. de Fonsc? 



Aphis pisi Kaltenbach. 



Siphonophora pisi Koch. 



Siphonophora uhnariae Passerini (nee Schrank). 



Nectarophora pisi Oestlund . 



Nectarophora destructor Johnson. 



Macrosiphum pisi Schouteden. 



Macrosiphum trifolii Pergande. 



IDENTITY OF THE SPECIES OCCURRING IN AMERICA. 



Macrosiphum pisi was first reported hi America by Cyrus Thomas 

 in 1878, although this record has been incorrectly discredited by most 

 subsequent authors. In 1900, following the first noteworthy out- 

 break of this pest in the United States, Johnson described the species 

 as new, calling it Nectarophora destructor. The following j^ear San- 

 derson reported studies to show that destructor is identical with pisi 

 of Europe, basing his conclusions partly by comparison with speci- 

 mens labeled pisi from Buckton. Evidently Buckton was confused 

 on this species, since one of the species sent Sanderson was certainly 

 not pisi, for the tips of the cornicles were reticulated, a character 

 which separates pisi from many closely related forms. Doubtless 

 this error on the part of Buckton led Sanderson to consider certain 

 American species with reticulated cornicles as synonyms or varieties 

 of pisi. In 1904 Pergande described a species under the name 

 Macrosiplium trifolii. 1 We have had an opportunity to examine the 

 type slide of trifolii Perg. and find it to be identical with pisi, and our 

 determination has been verified by Mr. Pergande. Notes on the 



1 Prof. Fred. V. Theobald (Theobald, Fred. V. The British species of the genus Macrosiphum, Passerini, 

 Pt. II. In Jour. Econ. Biol., v. 8, no. 3, p. 139, fig. 40, Sept. 29, 1913) has described a new species under the 

 name M. trifolii, overlooking the fan thai the name is preoccupied. We therefore propose for this species 

 Macrosiphum thcobaldii n. n. It is distinguished from pisi, according to Theobald, only by the usually 

 paler green color, the absence of sensori a on an tennal segment III of the wingless female, and relatively 

 thicker antenna?, which are rather variable characters for this genus, Winged forms verejiot observed 

 by Theobald. Itis not improbable that this will prove t<> be pisi. 



