242 
HEM1PTERA. 
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. Iiausmann,* 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, J 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 Iris 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. 
