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 antenna?, 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 (Carya porcina), in 

 all stages of growth, from the first to the middle of July. 

 It is the Aphis * Caryce 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 hag no terminal stylet, 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. 



