58 BULLETIN" 826, IT. S. DEPARTMENT OF AGRICULTURE. 



The genus Myzus was erected with Aphis cerasi Fab. as type. 

 In the same year Passerini used Aphis persicae Sulz. as type of 

 Rhopalosiphum Koch. Aphis nymphaeae Jj., however, had been set 

 as the type of that genus in 1856. Persicae seems to be very closely 

 related to cerasi and' Rhopalosiphum (Koch) Pass., therefore, is 

 placed as a synonym of Myzus. 



In 1913 Van der Goot placed certain other species in Myzus and 

 the type of the genus he made the type of his Myzoides. This will 

 evidently then become a synonym, as it has the same type. 



In 1916 Van der Goot erected the genus Neomyzus with circum- 

 fiexum Buckt. as type. While the frontal tubercles of this species do 

 not converge quite to the same extent as those of cerasi, they are 

 quite similar and the cauda is somewhat conical as in that species. 

 Neou^zus, therefore, is believed to be a synonym. Mordwilko used 

 the name Myzodes with tabaci Mord. as type. This species he does 

 not fully describe, but gives a figure and describes the characters of 

 the genus. From the information given it appears to be a synonym 

 of Myzus. The writer also believes that the genus Ovatus V. d. Goot 

 is a synonym of Myzus. This genus was erected with mespili 

 V. d. Goot as type. The genus Aulacorthum Mord. was erected 

 with pelargonii as type. A study of this species shows the antennal 

 tubercles very similar to those of cerasi. The cornicles, too, are quite 

 similar, although the cauda is a little more Aphis-like. The writer 

 believes this genus is a synonym. 



Characters.— Head with distinct antennal tubercles present which, particularly in 

 the apterous form, project inward and are strongly gibbous. Antennse of six seg- 

 ments, the first segment gibbous like the antennal tubercles. Wing venation normal. 

 Cornicles rather long and subcylindrical. Cauda somewhat short and conical, con- 

 stricted very slightly, if at all. 



Type (fixed by Passerini, 1860), Aphis cerasi Fab. 



Genus PHORODON Passerini. 

 Plate VIII, N-Q. 



18G0. Phorodon Tasserini, Gli Afldi, p. 27. 



Characters. — Head in the alate form with distinct antennal tubercles which project 

 somewhat inward, first antennal segment gibbous. In the apterous form the antennal 

 tubercles possess very prominent projections which extend forward in front of the 

 head. First antennal segment with a projecting process. Fore wings with media 

 twice branched; hind wings with both media and cubitus present. Cornicles cylin- 

 drical, in the apterous form somewhat curved; cauda rather acutely conical, not as 

 long as the cornicles. - 



Males as a rule winged and oviparous females apterous. 



Type (fixed by Passerini, 1860), Aphis humuli Schrk. 



Genus RHOPALOSIPHONINUS, n. gen. 

 Plate IV, D-F. 



The genus Rhopalosiphoninus is erected for latysiphon Davidson, 

 a species with very peculiar cornicles. It appears to be somewhat 

 related to Amphorophora. 



