190 INSECTS OF MASSACHUSETTS. 



they frequently prey, treat the plant-lice with the utmost gentle- 

 ness, 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 ich- 

 neumon flies that are for ever hovering near to deposit their eggs 

 in the bodies of the lice. 



Plant-lice differ very much in form, color, clothing, and in the 

 length of the honey-tubes. Some have these tubes quite long, as 

 the rose-louse, Aphis Rosm, 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 

 Brassicaz, 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* Caryaz 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 

 stylet, and the honey-tubes are very short. Its body is covered 

 with a bluish white substance like the bloom of a plum, with four 

 rows of little transverse black spots on the back ; the top of the 

 thorax, and the veins of the wings are black, as are also the 

 shanks, the feet, and the antennae, which are clothed with black 

 hairs ; the thighs are reddish brown. This species sucks the sap 

 from the limbs and not from the leaves of the hickory. There is 



* It probably belongs to the genus Lachnus of llliger, or Cinara of Curtis. 



