40 
Tribe Siphonoph or ini ; 
A. Third discoidal vein twice forked. 
a. Honey tubes cylindrical, at least not clavate or 
enlarged in the middle, straight. 
b. Honey tubes long, their length greater than their 
diameter, exceeding that of the tail and* usually 
reaching beyond the tip of the abdomen. 
c. Antennae usually longer than the body; approxi¬ 
mate at the base; front apparently grooved; first 
joint of the antennae not toothed on the inside; 
honey tubes long, 
cc. Antennae scarcely longer than the body; re¬ 
mote at base; first joint and tubercles toothed 
or gibbous on the inner side at the tips. 
d. First joint toothed, and frontal tubercles gibbous 
internally; honey tubes long. 
dd. Similar except that the first joint is not toothed; 
honey tubes moderately long. 
bb. Honey tubes short, but little more than tubercles, 
.not exceeding the tail in length; antennae not 
longer, and sometimes shorter than the body. 
act. Honey tubes clavate, enlarged in the middle, and 
usually long. 
b. Honey tubes curved and usually, though not 
always, distinctly enlarged in the middle; antennae 
longer than the body; tail inconspicuous or ob¬ 
solete. 
bb. Honey tubes straight. 
c. Antennae longer than the body, at least in the 
winged form; tail large and conspicuous, (in our 
only species, frontal turbercle and first antennal 
joint gibbous). 
cc. Antennae shorter, or scarcely longer than the 
body; tail small and inconspicuous. 
AA. Third -discoidal vein of the front wings with 
but one fork. \ 
Tribe Aphidini. 
A. Honey tubes clavate; antenme rather short. 
AA. Honey tubes cylindrical, tuberculiforn or obso¬ 
lete, but never clavate. 
a. Seventh joint of the antennae , longer than the 
sixth or at least as long. 
b. Antennae pilose; honey tubes usually very short 
or obsolete; body also of apterous individuals 
often hairy or tuberculate. 
bb. Antennae smooth, rarely slightly pilose. 
c. Honey tubes longer than thick, cylindrical. 
cc. Honey tubes tuberculiform or sub-obsolete. 
(Genera.) 
l| 
Siph onoph ora. 
■ 
PZiorodon. 
Myzus. 
Ilyalopterus. 
Drepanosiph um. 
Megoura. 
Rh op adosiph um. 
Toxoptera. 
Genera. 
Aiphocorytie. 
Oh aitophorus. 
Aphis. 
Myzocallis. 
