45 
This has in some instances been carried too far, the characters Selected 
being so trivial or indefinite as, to render the generic distinctions 
of no value for scientific use. < 
Passerini, in his excellent papers on these insects began the reform 
movement by dispensing with some of Koch's numerous genera, and I 
have here attempted to carry it still further by combining some of 
his generic groups where the characters selected appear to be of little 
value. 
Most of the s pecies are aerial, and as a general rule reside on 
the leaves, tender twigs or branches of plants or on the stems of suc- 
bulent plants. As examples of the group the following well known 
spe.cies may be named: the Grain Aphis, Rose Aphis, Hop Aphis, 
Cabbage Plant-louse, Apple Plant-louse, &c. 
I think it more than probable that some of the species belonging to 
this sub-family are dimorphic and reside during the winter on the 
roots of plants; and it is possible that some which are now counted 
rs apterous, root feeding species, are but other forms of true Aphides. 
Buckton, who bases his sub-division into sub-families on the wing 
venation alone, includes in this group the hachninw of Passerini, but 
separates the sub-families into two sections corresponding with 
Passerini’s Aphidinae, and Lachninoe. 
I have followed him in combining the two groups into one sub¬ 
family, but have divided the sub-family into three sections or tribes: 
\Siphonophorini , Aplxidini and Lachinini, as shown in the preceding 
^able. But this arrangement is not strictly followed out in the suc¬ 
ceeding pages, which were written previous to this part of the report, 
md previous to the formation of the last preceding synoptical tables. 
The species of Aphidinae (exclusive of Laohnini)* haver the head 
*mall; eyes globular and somewhat prominent, and often in the winged 
individuals they have a distinct tubercle on the back part. The an- 
:ennae vary considerably in length, being in some cases shorter than 
:he body, but usually equaling or exceeding it in length; composed of 
seven joints, the first and second short and thick, their length seldom 
more than their diameter, the others slender and cylindrical; the third 
much longer than the first and second combined, and usually longer 
:han either of the following; seventh slender and bristle-like, and usu- 
illy much longer than the sixth. Beak of medium length or short, 
ind standing out nearly perpendicular. Wings large, erect in repose; 
he front pair with the third discoidal vein twice forked (except in 
Woxopterci) ; the hind wings with two branch veins. The abdomen 
usually furnished with honey-tubes. The hind legs usually much 
onger than the others. The body always naked or nearly so, at least 
t is never covered with the downy or cottony substance found on the 
wooly lice. 
They always operate on the surface of plants, never enclosing them¬ 
selves in galls; being found chiefly on the leaves, tender twigs, branches 
Dr fruit stems, and are extremely common, being diffused on almost 
ivery kind of vegetation. They resemble each other so closely that 
t is very difficult to distin piish one species from another, hence the 
*Notf..—T hese characters apply more particularly to Aphidinae , as given by Pesserini, 
vhich includes, as set forth in my synoptical table, Siphnopfmrini and Aphidini. The 
■haracters of Lachnini are given hereafter. 
( 
;jA 
'Y 
i 
LJ* 
SJ 
is* 
Mi 
