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The viue-louse, Phylloxera vastatrlx, Plauclioi], belongs to the class In- 

 secta, order Hemiptcra, ^nh- ovUer Homoptera^ family of plant-lice, Phyto- 

 plitliires^ tribe of leaf-lice, Aphides^ in which are numerous genera, as 

 MMzoMus, Eriosoma, Cliermes, Lackmis, Aphis, &c. The vine-louse appears 

 to belong to this last, though Cornu places it between A])his and Coccus. 

 It is so small as scarcely to be distinguished by the naked eye, oval, with 

 a thick body, and blunt abdomen comj)osed of seven rings, six slender 

 legs with short feet, a small, beak-shaped, incurved head, with a i)robos- 

 cis composed of four sucking-tubes, that usually lie on its breast. Full- 

 grown insects are somewhat warty, and are a bright yellow. 



Like other leaf-lice, they increase partheno-genetically ; the males first 

 appear just before winter in small numbers in the last brood of the sea- 

 son, and after impregnation the females lay eggs which develop the fol- 

 lowing spring. These eggs produce only females, called nurses, who, 

 without further commerce, lay eggs, and are also, to some extent, said to 

 be viviparous. This last fact has rarely been observed in the Phyllox- 

 era, and is doubted by the French Academy. This method of propaga- 

 tion continues until the power of a sexual increase is exhausted, when 

 males, usually winged, are again developed. At the same time the so- 

 called " nurses " become nymphs, or dark-colored, winged, and perfect 

 insects.* By this alternation of generation the increase of numbers is 

 enormously rapid. Eeaumur places it at 6,000,000,000 from one female 

 in a summer, but this is too low; for if a nurse Phylloxera lays 30 eggs, 

 vrhich produce i)erfect insects, their descendants in the twelfth genera- 

 tion will number 17,714,700,000,000,000 individuals. The injury caused 

 by a single puncture such as they make in the bark of the roots, or even 

 several, is very slight, but w hen multiplied by such immense numbers, 

 is ample cause for the serious damages which have been inflicted on the 

 European vineyards. 



The food of this class of insects is the sap of plants, which they usu- 

 ally obtain from the leaves, on which they form galls. Some of the 

 species change their host-plant with each change of form, the perfect 

 insect feeding on a different jjlant from that on which its nurse-mother 

 fed 5 and this fact is said by Lichteustein to have been observed with 

 regard to the Phylloxera, but it cannot be considered as fully estab- 

 lished. 



The viue-louse differs from the rest of its kind in living under the 

 ground, (though in America it is said to form galls on the leaves. They 

 have only been observed in Europe by Planchon, Signoret, and Lalimau, 

 and the insects were not entirely identical with those on the roots.)t 



The full-grown insect sits motionless on the roots, having inserted its 

 sucking-tubes, of which, according to Eosler, it uses two to withdraw 

 the sap, and the other two to pour into the wound a liquid excrement, 

 which, i)erhaps, is more injurious than the wound itself. The resulting 

 semi-transparent swellings are the most certain indication of the pres- 



*According to Balbiani's latest researches, there are at least four diflferent forms of the in- 

 sect capable of reproduction, not counting the eggs or the nymphs. 



t Persons unacquainted with the Phylloxera are liable to mistake for it the grape-mite, 

 (Pnytophus vitis.) This insect belongs to the Arachnida, and eats the buds and young 

 leaves in spring. Its presence is readily perceived by the bladdery galls on the upper sur- 

 '"ace of the leaves, in which a pinkish, spore-like dust will be found, consisting of these 

 mites laying their eggs. They may be destroyed by gathering and burning the vine-leaves 

 in the fall, so that no eggs shall remain over winter. They are about .032 — .09d millimeter 

 in diameter, the females larger than the males. They are peculiar in their organs of respira- 

 tion, which open into the intestinal canal. It is not yet certain if the application of sul- 

 phur is as destructive to this pest as it is to the Oidium. Several other mites, as Acarus 

 and Haplophora, (Riley,) live on the vine. 



