220 INSECTS INJURIOUS TO VEGETATION. 



Sometimes the insect's body is not large enough to cover all 

 her eggs, in which case she beds them in a considerable quan- 

 tity 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 tw^o are pro- 

 duced 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 vei-y 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 insects, 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 color very near to that of the bark of the tree. These 

 insects resemble in shape one which was described by Reau- 

 mur* in 1738, who found it on the elm in France, and Geoffroy 

 named the insect Coccus arborum linearis, while Gmelin called 

 it concliiformis. This, or one much like it, is very abundant 

 upon apple-trees in England, as we learn from Dr. Shawf and 

 IVIr. Kirby ; J and Mr. Rennie § 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 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 

 sohtary. It is true that on some of our indigenous forest-trees 

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



* Memoires, Vol. IV. p. 69, plate 5, figs. 5, G, 7. 

 t General Zoology, Vol. VI., Part I. p. 196. 

 X Introduction to Entomology, Vol. I. p. 201. 

 § Insect Transformations, p. 92. 



