THE PHYLLOXERA, OR GRAPE LOUSE OF THE VINE. 119 



they swarm in thousands. A quart pot of earth contain- 

 ing infested roots will for three weeks yield a dozen of 

 these alate (winged) forms daily, each of which contains 

 one, two, up to eight egg-like bodies of different sizes, 

 which are deposited sometimes under the leaf, and some- 

 times in the fissures of the bark. This winged insect is 

 the " Pupifer " of Lichtenstein, and furnishes through the 

 above pseudova the true males and females. 



" Winged (jpseudo) female. Body greenish-yellow, fusi- 

 form. Abdomen tapering towards the apex. Head 

 broad ; eyes large and red. Antennae rather short, third 

 joint much the longest, strongly ringed, and apparently 

 without any marked tubercle. Wings carried pentwise, 

 membrane hyaline and very delicate. Cubitus broad and 

 yellow. Stigma very faint. The three nervures pale 

 yellow. 



" The only specimen I have examined contained one 

 single large egg, measuring 0*015 of an inch. The 

 identity of species of these aerial and subterraneous 

 insects is now too well known to require comment beyond 

 the fact that Professors Riley, Balbiani, and Cornu have 

 all proved that the two kinds may be compelled by artifice 

 to change their habitats. The apterous larvae taken from 

 the roots, however, show much disinclination to feed on 

 the leaves, and probably they never would raise the galls. 



" Professor Balbiani has shown that the appearance of 

 the winged insect is not necessary to complete the cycle 

 of life. In this case, when a recurrence to the male 

 becomes necessary, an apterous form must yield the eggs 

 which give rise to the sexes, just as it occurs in the case 

 of Phylloxera punctata. 



" The American phylloxera appears to have as many as 

 six different periods for egg-laying ; but the European 

 insect, from Lichtenstein's observations, would appear to 

 have fewer. The root-feeding larvae undergo a hyberna- 

 tion, during which time they shrivel up without losing 

 vitality. In April they wake up, become supple and 

 inflated from the imbibition of sap, and then it is that the 

 chemical insecticides have the greatest activity upon 

 them. 



