BARK-LICE. 



BARK-LICE. 



come perfect pupoe, the rudiments of wings, 

 antennae, feet, &c., being discoverable on rais- 

 ing the shells. If we follow the progress of 

 these small lice, which are to produce the 

 males, we shall see, in process of time, a pair 

 of threads and the tips of the wings protruding 

 beneath the shell at its lower elevated part, 

 and through this little fissure the perfect in- 

 sect at length backs out. After the larger lice 

 have become fixed and have thrown off their 

 outer coats, they enter upon the pupa or 

 chrysalis state, which continues for a longer 

 or shorter period according to the species. 

 But when they have become mature, they do 

 not leave the skins or shells covering their 

 bodies, which continue flexible for a time. 

 These larger insects are the females, and are 

 destined to remain immovable, and never 

 change their place after they 'have once be- 

 come stationary. The male is exceedingly 

 small in comparison to the female, and is pro- 

 vided with only two wings, which are usually 

 very large, and lie flatly on the top of the 

 body. After the insects have paired, the body 

 of the female increases in size, or becomes 

 quite convex, for a time, and ever afterwards 

 remains without alteration; but serves to 

 shelter the eggs which are to give birth to her 

 future offspring. These eggs, when matured, 

 pass under the body of the mother, and the 

 latter by degrees shrink more and more till 

 nothing is left but the dry outer convex skin, 

 and the insect perishes on the spot. Some- 

 times the insect's body is not large enough to 

 cover all her eggs, in which case she beds 

 them in a considerable quantity of the down 

 that issues from the under or hinder part of 

 her body. There are several broods of some 

 species in the year ; of the bark-louse of the 

 apple-tree at least two are produced in one 

 season. It is probable that the insects of the 

 second or last brood pair in the autumn, after 

 which the males die, but the females survive 

 the winter, and lay their eggs in the following 

 spring. 



" Young apple-trees, and the extremities of 

 the limbs of older trees are very much subject 

 to the attacks of a small species of bark-louse. 

 The limbs and smooth parts of the trunks are 

 sometimes completely covered with these in- 

 sects, and present a very singularly wrinkled 

 and rough appearance from the bodies which 

 are crowded closely together. In the winter 

 these insects are torpid, and apparently dead. 

 They measure about one-tenth of an inch in 

 length, are of an oblong oval shape, gradually 

 decreasing to a point at one end, and are of a 

 brownish colour very near to that of the bark 

 of the tree. These insects resemble in shape 

 one which was described by Reaumur in 1738, 

 who found it on the elm in France, and 

 Geoffrey named the insect Coccus arhnrum 

 linearis, while Gmelin called it conchiformis. 

 This, or one much like it, is very abundant 



E apple-trees in England, as we learn from 

 haw and Mr. Kirby; and Mr. Rennie 

 that he found it in great plenty on cur- 

 rant-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 

 138 



! by Reaumur 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 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 

 1 account that we have of the occurrence of 

 bark-lice on apple-trees, in this country, is a 

 communication by Mr. Enoch Perley, of Bridge- 

 town, Maine, written in 1794, and published 

 among the early papers of the Massachusetts 

 Agricultural Society. These insects have now 

 I become extremely common, and infest our nur- 

 1 series 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 colour, 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 transforma- 

 tions 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 pro- 

 vided to check the increase of these bark-lice, 

 are birds, many of which, especially those of 

 the genera Parus and Regulm, containing the 

 chickadee and our wrens, devour great quan- 

 tities 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 de- 

 stroyed 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 brush, and as 

 high as practicable, so as to cover the whole 

 surface, and fill all the cracks in the bark. 

 The proper time for washing over the trees is 

 in the early part of June, when the insects are 

 young and tender. These insects may also be 

 killed by using in the same way a solution 

 of two pounds of potash in seven quarts of 

 water, or a pickle consisting of a quart of com- 

 mon salt in two gallons of water. 



"There has been found on the apple and 

 pear tree another kind of bark-louse, which 

 differs from the foregoing in many important 

 particulars, and approaches nearest to a spe- 

 cies inhabiting the aspen in Sweden, of which 

 a description has been given by Dalman in ihe 

 , ' Transactions of the Royal Academy of Sci- 



