202 INSECTS INJURIOUS TO VEGETATION. 



nearly solitary. It is true that on some of our indigenous forest- 

 trees bark-lice of nearly the same form and appearance have been 

 observed ; 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 Mr. Enoch Perley, of Bridgetown, Maine, 

 written in 1794, and pubhshed among the early papers of the 

 Massachusetts Agricultural Society*. 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 station- 

 ary, 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 provide 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, espe- 

 cially those of the genera Parus and Regulus, containing the chick- 

 adee and our wrens, devour great quantities of these lice. I have 

 also found that these insects are preyed upon by internal parasites, 

 minute ichneumon flies, and the holes (which are as small as if 

 made with a fine needle), through which these little insects come 

 forth, may be seen on the backs of a great many of the lice 

 which have been destroyed by their intestine foes. The best ap- 

 plication for the destruction of the lice is a wash made of two 

 parts of soft soap and eight of water, with which is to be mixed 

 lime enough to bring it to the consistence of thick white-wash. 

 This is to be put upon the trunks and limbs of the trees with a 



* See Papers for 1796, p. 32. 



