122 FRUIT CULTURE UNDER GLASS. 



the second after laying-time. Some uncertainty, however, hangs 

 over the number of these changes, as the cast-off skins are often 

 found mixed up with groups of pucerons of different ages, and 

 it is difficult to distinguish them. On the morbid tuberosities 

 of the fibrous vine-roots, or on the offshoots of the roots, the 

 pucerons (perhaps better nourished) seem to pass more quickly 

 through the different phases I have described ; but excepting 

 that their colour is paler, they present no marked difference. 



" The winged form of the Phylloxera might easily be taken for a 

 separate species. The rare specimens which I have seen have all 

 come from the pucerons nourished on the newly-attacked vine- 

 radicles. In their infant (or it mig^it be called their larva) state 

 they resemble those which I have suggested may be males, but 

 the buckler soon becomes more strongly marked than in these 

 last ; and a kind of band seems distinctly to define the separation 

 between this and the abdomen. The sheaths of the wings, trian- 

 gular-shaped and of a greyish colour, appear on both sides of the 

 buckler. It is easy to predict the advent of a winged insect from 

 this chrysalis. When one of these nymphse is seen to quit its 

 place and to crawl over the root, or up the side of the bottle where 

 it may have been put, its transformation is near. Soon, instead 

 of a sort of pupa, a beautiful little fly appears, whose two pairs of 

 wings, crossed horizontally, are much larger than its body. 



" It is impossible to doubt the identity of this insect with the 

 puceron which formed one of the swarm on the vine-root. The 

 details of the structure of certain organs — the antennae, claws, 

 tarsi, and suckers — establish their identity. 



" The horizontal position of the wings completely distinguishes 

 the Phylloxera from the true aphis, whose wings are always more 

 or less inclined upwards. The two larger wings, obliquely oboval 

 and cuniform, have a lineal areole on the larger basilary half ol 

 their outer edge ; and this is enclosed in an interior ' nervure,' 

 which answers, I suppose, to the radial muscle. One single oblique 

 nervure (or corneous division) is detached from this last, and 

 reaches to the inner edge. Two other lines start from the end of 

 the wing, and, becoming narrower as they proceed, advance towards 

 the oblique nervure, but end before reaching it. These are not, pei- 

 haps, nervures, but rather folds, for I have observed them absent. 

 " The inferior wings, both narrower and much shorter, have a 

 marginal nervure miming from the base to the middle, but it 

 loses itself in a gentle protuberance, which the wing shows in this 



