PHYLLOXERA VASTATRIX. 57 



insect would become, if every phase in its metamor- 

 phosis should be fully studied and described. 



In illustrating the development of the vine Aphis 

 only a few forms can be here figured. This necessary 

 restriction has been, indeed, applied to all the species 

 I have attempted to set forth in this Monograph ; but, 

 as a rule, I have chosen types of most marked phases. 

 With reference to Ph. vastatrix the reader can consult 

 the engraved plate issued by M. Lichtenstein in 1876, 

 in which twenty-one forms of the insect are repre- 

 sented. Some present lacunae may be supplied from 

 thence. Any one attempting to draw twenty indivi- 

 duals of the same species under the camera will remark 

 the diversity of proportion of their organs at different 

 times of their development. 



Phylloxera vastatrix may be conveniently grouped 

 for description into the aerial and the subterranean 

 forms, which answer to the terms Grallascola and Radi- 

 cicola of Professor Riley. 



Aerial apterous female. 



Fundatrix. 



Phylloxera vastatrix, Planchon. PI. CXXII, figs. 

 7, 8, and PI. OXXIV, CXXV. 



Pemphigus vitifolii, Asa Fitch. 

 Peritymbia vitisana, Westwood. 

 P)actylosiphozra vitifolii, Shinier. 

 Phylloxera vastatrix, Lichtenstein, Riley, Signoret, 

 Cornu, Balbiani. 



Inch. Millimetres. 



Size of the body 0-070x0-050 177 X 1'26 



Length of antenna? 0-009 0*22. 



Body nearly circular, flask-shaped, drawn out at the 

 tail, which ends in a short and truncated ovipositor. 

 Colour amber-yellow, fuscous, or ferruginous ; spotted 



