PHYLLOXERA VASTATRIX. S9 



destruction to the European vines. In America the 

 aerial form appears to produce the greatest evil. 



Subterranean apterous female. 



These apterous larvse are smaller than the f undatrix, 

 and measure 0*026 X 0*01 6 of an inch. They are amber- 

 yellow, with an olive stain towards the head and vent. 

 In later generations the forms are more flask-like and 

 colour ferruginous. During their life underground 

 they oviposit. One specimen, however, on dissection 

 contained only eight eggs, but this number is not con- 

 stant. The egg-like bodies are of a pale yellow colour 

 and shining. When the larger roots are attacked the 

 cortex is loosened ; it rots and scales off under the 

 irritation of the insects, as seen in PL CXXIV, fig. 5. 

 When the small fibres are affected, swellings and 

 nodules mark the injury done, as seen in PL CXXV, 

 fig. 10. 



Professor Riley states that this root modification of 

 Phylloxera passes through five or six generations, 

 which fact will account for the various forms and sizes 

 seen simultaneously crowding the roots of the plant. 

 The American forms appear to be more tuberculate 

 than those I have been able to examine through M. 

 Lichtenstein's courtesy. 



About the month of July many of these underground 

 forms pass into nymphs and come to the surface, where 

 they develop wings, and then they fly to distant vine- 

 yards to carry on the invasion. In America during 

 August they swarm in thousands. A quart pot of 

 earth containing infested roots will for three weeks 

 yield a dozen of these alate forms daily, each of which 

 contains one, two, up to eight egg-like bodies of dif- 

 ferent sizes, which are deposited sometimes under the 

 leaf, and sometimes 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. 



