a. Fourth vein of the fore wings nearly straight; stigma linear. 
Lachnus. 
cut. Fourth vein of the fore wings curved; the stigma trapezoidal. 
h. Abdomen bare. 
c. Rostrum short, not extending to the middle legs. Callipterus 
cc. Rostrum more or less long, extending at least to the hind 
legs. Pterochlorus. 
bb. Abdomen wooly. Phyllaphis. 
■ , ■ / 
Sub-family III. Pempiiigin^e. 
A. . Cubital vein forked at the tip. Schizoneura. 
A A. Cubital vein simple. 
a. Hind wings with two oblique veins. Pemphigus, 
aa. Hind wings with-one oblique vein. 
b. Wings dehexed in repose. Tetraneura. 
bb. Wi ngs horizontal in repose. Aploneura. 
\ 
Sub-family IV. Riiizobiin.e. 
A. Third joint of the antennae much longer than the fourth. Forda . 
AA. Third and fourth joints of the antennae nearly equal in length. 
Rhizobms. 
Sub-family V. Tyciiein.e. 
Only one genus in this sub-family. Tychea. 
Sub-family VI. Ciiermesinje. 
A. Antennae five-jointed. 
a. Fore wings with four oblique veins; the cubital vein forked 
Vacuna. 
aa. Fore wings with three oblique simple veins. Chermes. 
AA. Antennae three-jointed. Phylloxera. 
Mr. Walsh, in his article on the Aphides, in Vol. I., Proc. Ent. Soc. 
Phila., gives the following synoptical table of the United * States 
genera: 
Synoptical Table of the United States Genera. 
A. Iloney-tubes present; antennae seven-jointed; front wings with three 
discoidals, the third two branched; hind wings with two discoidals. 
a Honey-tubes long; antennae with joint seven longer than six. 
b. Stigrnal Vein present. Aphis, 
bb. Stigrnal vein absent. ✓ Calaphis. 
an. Honey-tubes short, sub-obsolete; antennae with joint seven longer 
than six. 
b. Discoidals of the front wings of equal thickness; wings horizon¬ 
tally folded, Callipterus. 
bb. front wings with the first tWQ discoidals morg robust; wings 
steeply roofed. Lachnus. 
