242 HEMIPTEEA. 



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 infesting 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, $ is found in the or- 

 chards 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 miscalled 

 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 Naturalist," from which, and from Hausmann's de- 

 scription, the following 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 en- 

 ,, veloped 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 sur- 

 face of the ground, especially if there are suckers springing 

 from the same place. The young, when first hatched, are 

 covered with a very short and fine down, and appear in 



* Illiger's Magazin, Vol. I. p. 440. $ Insect Miscellanies, p. 180. 



t Salisbury's Hints on Orchards, p. 39. 



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



