4.4.0 MODERN CLASSIFICATION OF INSECTS. 
caused by the punctures of the insects, which is known under the name 
of honey-dew. 
Each family of plant lice in spring and summer consists of indi- 
viduals always wingless and of pupz; all these, however, are females, 
which produce living young withcut a previous union with the other 
sex; and Bonnet, whose researches have removed all doubts upon the 
subject, has clearly shown that this power is exercised at least through 
nine generations, which are produced within the space of three months. 
Whilst Duvau thus obtained eleven generations in seven months, and 
Kyber even observed that a colony of Aphis Dianthi, brought into a 
constantly heated room, continued to propagate for four years, with a 
single impregnation of a female by a male, the young being constantly 
produced of the female sex. The males, of which some are winged, 
and others apterous in the same society, are not born until the end of 
the summer or autumn. They fecundate the last generation, pro- 
duced by the previously born specimens, consisting of wingless females, 
which then deposit fecundated eggs, which remain through the winter, 
and produce young in the spring capable of reproduction without 
fresh impregnation. It is impossible in this work to enter into the 
numerous details relative to these insects, which have attracted so 
much of the attention of naturalists ; I must therefore refer more par- 
ticularly to the memoirs of Bonnet, Réaumur (Mém. tom. iii. mém. 9 
and 11., and tom. vi. mém. 13.), De Geer (Mém. tom. iil. chap. 2 and 3.) 
Curtis (Observ. on Aphides, in Trans. Linn. Soc. vol. vi. Phil. Trans. 
1771.), Sauvages (on Honey-dew, in Journ. de Physique, tom. 1., and 
in his memoirs), as well as the elaborate anatomical researches of 
Duvau, Dutrochet, and Morrem, above referred to. 
Many of the species have the body densely clothed with a white 
cottony secretion, either in threads or flakes ; amongst these may 
particularly be mentioned the Aphis lanigera, or American blight * 
as it is termed, which infests the stems of apple trees, sometimes 
totally destroying them. ‘This species belongs to the genus Lachnus 
Iilig. Myzoxyle Blot, Eriosoma Leach, differing from Aphis in the 
neuration of the wings, as well as in the want of tubercles at the ex- 
tremity of the body for the secretion of honey-dew. The antennz also 
* The details of the history of this species are given by Knight and Sir J. Banks 
in the Horticult. Trans.; by Knapp in the Journal of a Naturalist ; Annales Sci. Nat., 
March 1831; D’Arcilly in Bull. de ? Acad. Ebboicienne du Département de U Eure, 
1834; Audouin in Ann. Soc. Ent. France, tom. v. p. 9. App. 
