58 BULLETIN 826, U. S. DEPARTMENT OF AGRICULTURE, 
The genus Myzus was erected with Aphis cerasi Fab. as type. 
In the same year Passerini used Apliis persicae Sulz. as type of 
Rhopalosiphum Koch. Apliis nympliaeae L., 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- 
jiexum 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. ' 
Neomyzus, 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. Antennte 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. 
1S00. Phorodon Passerini, 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 aa 
long as the cornicles. 
Males as a rule winged and oviparous females apterous. 
Type (fixed by Passerini, 1860), Aphis humvli Schrk. 
Genus RHOPALOSIPHONINUS, n. gen. 
Plate IV, D-F. 
The genus Rhopalosiphoninus is erected for laty siphon Davidson, 
a species with very peculiar cornicles. It appears to be somewhat 
related to Amphorophora. 
