208 INSECTS INJURIOUS TO VEGETATION. 



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 ichneu- 

 mon 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 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 Brassiccc, 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 ( Cari/a porcina), in 

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

 It is the Aphis* Carija 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 w^ith 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 another large 

 species, living in the same way on the under side of the 

 branches of various kinds of willows, and clustered together 

 in great numbers. About the first of October they are found 

 in the winged state. The body measures one tenth of an inch 

 in length, and the wings expand about four tenths. The stylet 

 is wanting; the body is black and without spots; the wings 

 are transparent, but their veins, the short honey-tubercles, the 

 third joint of the antennae, and the legs, are tawny yellow. 



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



