522 HEMIPTERA. 



In Aphis the seven-jointed antennae are longer than the body, 

 the two basal joints short and thick, the seventh the longest, 

 and near the end of tlie abdomen there are two long lionej^ 

 tubes. Aphis avence Fabr. is abundant and very injurious to 

 the ears of wlieat, sucking out the sap and greatly reducing the 

 bulk of the corn. In certain jears it has spread over the 

 country in immense numbers. Apjhis mali Fabr. (Fig. 518, 

 winged female; Fig. 519, asexual female), and A. malifolice 

 Fitch are found on the apple ; A. cerasi Fabr. on the cherry ; 

 A. persicoi Sulzer on the peach, and A. hrassicm Linn, on the 

 cabbage. There are about thirty species known in this 

 country. 



In Lachnus the sixth joint of the antennae is shorter than 

 the seventh, and the honey tubes are very short. Lachnus 

 strobi is found on the white pine bushes often in great numbers. 

 Lachnus canjce Harris is a very large species 

 which lives on the Hickory. Mr. Walsh states 

 that he has "noticed in the autumn, numerous 

 apterous females on the same tree, Avhich lived 

 Fig. 519. many daj'S and laid their eggs in confinement, 

 but died without assuming wings." The genus Eriosoma differs 

 in having no honey tubes, and in having onl}^ two median (dis- 

 coidal) cells. The species are covered with a woolly flocculent 

 .substance, secreted from the abdomen, though no special 

 glands for tliis purpose have 3'et been discovered, while but lit- 

 tle "honey" is exuded from the orifices of the aborted honej^- 

 tubes. Eriosoma kmigera Hausmann, the Apple-blight, is 

 black, with the abdomen honey yellow. The eggs are laid in 

 the axils of the branches, especially near the roots of the tree, 

 if there are any suckers present, and are enveloped in the pow- 

 dery substance of the abdomen of the female. By their stings 

 in the bark numerous warts and excresences are produced, 

 the leaves turn yellow and drop off, and the tree often dies. 

 Professor Verrill has found, about the middle of October, 

 among the wingless individuals, " a large number of both males 

 and females having well formed and rather large wings, but in 

 other respects closely resembling the rest." 



The genus Adelges was proposed by Vallot for certain broad, 

 flattened plant-lice, which attack coniferous trees, often raising 



