238 
HEMIPTERA. 
Other hand, the ants, though unsparing of other insects 
weaker than themselves, upon which they frequently prey, 
treat the plant-lice with the utmost gentleness, caressing 
them with their antennae, and apparently inviting them to 
give out the fluid by patting their sides. Nor are the lice 
inattentive to these solicitations, when in a state to gratify 
the ants, for whose sake they not only seem to shorten the 
periods of the discharge, but actually yield the fluid when 
thus pressed. A single louse has been known to give it drop 
by drop successively to a number of ants, that were waiting 
anxiously to receive it. When the plant-lice cast their skins, 
the ants instantly remove the latter, nor will they allow any 
dirt or rubbish to remain upon or about them. They even 
protect them from their enemies, and run about them in the 
hot sunshine to drive away the little ichneumon flies that 
are forever hovering near to deposit their eggs in the bodies 
of the lice. 
Plant-lice differ veiy much in form, color, clothing, and 
in the length of the honey-tubes. Some have these tubes 
quite long, as the rose-louse. Aphis Rosce^ which is green, 
and has a little conical projection or stylet, as it is called, 
at the extremity of the body, between the two honey-tubes. 
The cabbage-louse. Aphis Brassicce^ has also long honey- 
tubes, but its body is covered with a whitish mealy substance. 
This species is very abundant on the under side of cabbage- 
leaves in the month of August. 
The largest species known to me is found in clusters 
beneath the limbs of the pig-nut hickory QCarya porcino)^ in 
all stages of growth, from the first to the middle of July. 
It is the Aphis ^ Caryoe of my Catalogue. Its body, in the 
winged state, measures one quarter of an inch to the end 
of the abdomen, and above four tenths of an inch to the tips 
of the upper wings, which expand rather more than seven 
tenths of an inch. It has no terminal stvlet, and the honey- 
tubes are very short. Its body is covered with a bluish-white 
* It probably belongs to the genus Lachnus of Illiger, or Cinara of Curtis. 
