BARK-LICE. 
253 
Kirby ; * and Mr. Rennie f states that he found it in great 
plenty on currant-bushes. 
It is highly probable that we have received this insect 
from Europe, but it is somewhat doubtful whether our apple- 
tree bark-louse be identical with the species found by Reau¬ 
mur on the elm ; and the doubt seems to be justified by the 
difference in the trees and in the habits of the insects, our 
species being gregarious, and that of the elm nearly solitary. 
It is true that on some of our indicrenous forest-trees bark- 
O 
lice of nearly the same form and appearance have been ob¬ 
served ; but it is by no means clear that they are of the 
same species as those on the apple-tree. The first account 
that we have of the occurrence of bark-lice on apple-trees, 
in this country, is a communication by jNIr. Enoch Perley, 
of Bridgeton, Maine, written in 1794, and published among 
the early papers of the Massachusetts Agricultural Society. J 
These insects have now become extremely common, and 
infest our nurseries and young trees to a very great extent. 
In the spring the eggs are readily to be seen on raising the 
little muscle-shaped scales beneath which they are concealed. 
These eggs are of a white color, and in shape nearly like 
those of snakes. Every shell contains from thirty to forty of 
them, imbedded in a small quantity of whitish friable down. 
They begin to hatch about the 25th of May, and finish 
about the 10th of June, according to Mr. Perley. The 
yonng, on their first appearance, are nearly white, very 
minnte, and nearly oval in form. In about ten days they 
become stationary, and early in June throw out a quantity 
of bluish-white down, soon after which their transformations 
are completed, and the females become fertile, and deposit 
their eggs. These, it seems, are hatched in the course of 
the summer, and the young come to their growth and pro¬ 
vide for a new brood before the ensuino; winter. 
Among the natural means which are provided to check 
the increase of these bark-lice are birds, many of which, 
* Introduction to Entomology, Vol. I. p. 201. 
t Insect Transformations, p. 92. t See Papers for 1796, p 32. 
