HEMIPTERA. 211 



or produce them generally differ from the others, in having 

 shorter antennae, being without honey-tubes, and in frequently 

 being clothed with a kind of white down, which, however, 

 disappears when the insects become winged. 



These downy plant-lice are now placed in the genus Erio- 

 soma, which means woolly body, and the most destructive 

 species belonging to it was first described, under the name of 

 Aphis lanigera, by Mr. Hausmann,* in the year 1801, as infest- 

 ing the apple-trees in Germany. It seems that it had been 

 noticed in England as early as the year 1787, and has since 

 acquired there the name of American blight, from the erroneous 

 supposition that it had been imported from this country. It 

 was known, however, to the French gardeners f for a long time 

 previous to both of the above dates, and, according to Mr. 

 Rennie,:J: is found in the orchards about Harfleur, in Normandy, 

 and is very destructive to the apple-trees in the department of 

 Calvados. There is now good reason to believe that the mis- 

 called American blight is not indigenous to this country, and 

 that it has been introduced here with fruit-trees from Europe. 

 Some persons, indeed, have supposed that it was not to be 

 found here at all, but the late Mr. Buel has stated § that it 

 existed on his apple-trees, and I have once or twice seen it on 

 apple-trees in Massachusetts, where, however, it still appears 

 to be rare, and consequently I have not been able to examine 

 the insects sufficiently myself. The best account that I have 

 seen of them is contained in Knapp's "Journal of a Natural- 

 ist," from which, and from Hausmann's description, the follow- 

 ing observations are chiefly extracted. 



The eggs of the woolly apple-tree louse are so small as not 

 to be distinguished without a microscope, and are enveloped 

 in a cotton-like substance furnished by the body of the insect. 

 They are deposited in the crotches of the branches and in the 

 chinks of the bark at or near the surface of the ground, es- 

 pecially if there are suckers springing from the same place. 

 The young, when first hatched, are covered with a very short 



* lUiger's Magazin, Yol. I. p. 440. t Salisbury's Hints on Orchards, p. 39. 



% Insect Miscellanies, p. 180. 



§ New England Farmer, Vol. YII. p. 169 ; Yol. IX. p. 178. 



