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Show 50 INSECTA. Sometimes the elytra and wings, oval or tn·a n?u1 ~~ r ' da nd without a fringe of ha.i rs aI ong th e mar gin ' are me. me or tectiform. The rostrum I.S very dI' stm· c t . The ta.r s1 are ter-minated by two hooks, and the antennre have but SIX or seven joints. Such is the genus APHIS, Lin. Which we divide in the following manner. APHIS, Properly so called, where the antennre a~e l~nger than t~e thorax and consist of seven joints, the third of which 1s elongated, t~e eyes are entire, and there are two horns or mammill<E at the posteriOr ex· tremity of the abdomen. . Almost all of them live in society on trees and plants, of whtch they suck the juices with their trunk. The two horns observed. at the posterior extremity of the abdomen in a great number of species are hollow tubes from which little globules of a transparent, honeylike fluid frequently exude, on which the Ant eagerly feeds. In each community, during the spring and summer, .we find Aphides that are always apterous, and semi-nymphs who~e wmgs are yet to be developed; all these individuals are females, which produ~e Jiving young ones that issue backwards from the venter o~ their mother, without previous copulation. The males, some of whtch are winged and others apterous, only appear towards the end of summer or ln autumn. They fecundify the last generation produced by the preceding individuals, which consists of unimpregnated apterous females. After coition the latter lay their eggs on branches of trees, where they remain during the winter, and from which, in the spring, proceed little Aphides, which soon multiply without the assistance of the males. The influence of a first fecundation is also extended to seven successive generations. Bonnet, to whom we are indebted for most of these facts, by isolating the females, obtained nine generations in the space of three months. The wounds inflicted on the leaves or tender twigs of plants, by Aphides, cause those parts of the vegetable to assume a variety of forms, as may be observed on the shoots of the Lime tret>, the leaves of Goosebet·t·y bushes, Apple trees, and particularly those of the Elm, Poplat·, Pistachio, in which they produce vesicles or excres· HEMIPTERA. 51 cences enclosing colonies of Aphides, and frequently an abundant saccharine fluid. Most of these Insects are covered with a farinaceous substance, or cotton-like filaments, sometimes arranged in bundles. The Iarvre of the Hemerobii, those of several Diptera, and of Coccinellre, destroy immense numbers of Aphides. M. A. Duvau has communicated to the Academie des Sciences, the interesting result of his researches on these Insects. His Memoir has been inserted in the Annales du Museum d'Histoire Naturelle . .11. quercus, L.; Reaum., Insect., III, xxviii, 5, 10. Brown; remarkable for its rostrum, which is at least thrice as long as the body . .11. fagi, L.; Reaum., lb., xxvi, I. Completely covered with white down resembling cotton( 1 ). ALEYRODEs, Lat.-TINEA, Lin. Where the antennre are shorter and hexarticulated, and the eyes are emarginated. .11. proletella; Tinea proletella, L.; Reaum., lb., II, xxv, 1, 7. · Resembling a little Phal<Ena; white, with a blackish point and spot on each elytron. Under the leaves of the Chelidonium majus, Brassic<E, Oak, &c. The larva is oval, much flattened, in the form of a little scale, and resembles that of the Psyllre. The chrysalis is fixed and enclosed in an envelope, so that this Insect unrlergoes a complete metamorphosis. (1) M. Blot, corresponding member of the Linnean Society of Caen, had published, in the Mem. de la Soc. Lin. de Cacn, 1824, p. 114, some curious observations on a particular species which is ve1-y injurious to the Apple-trees in the department of Calvados, by destroying their young shoots. He considers it as the type of a new genus, Myzo:r.yle. De Geer had previously described an Aphis of the same tree, but as Messrs Lepeletier and Serville-Encyc. Method., article Puceron,-justly remark, that species, although also hurtful to the Apple-tree, differs essentially from the preceding one. The abdomen of the other is not furnished with horns; its antenna: are shorter, and, according to M. Blot, present but five joints, of which the second is the longest. We suspect that it re-enters into our third division-Gener. Crust. et Insect.-of the genus Aphis. For the other species, see the works already quoted, and the Faun. Bavar., Schrank. ., ... |