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 

 diiference 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 indigenous forest-trees baric- 

 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 j\Ir. 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 

 young, on their first appearance, are nearly white, very 

 minute, 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- 

 \ade for a new brood before the ensuing 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. J See Papers for 1796, p. 32. 



