The Collaborative International Dictionary of English v.0.48:

Phylloxera \Phyl`lox*e"ra\, n. [NL., fr. Gr. fy`llon leaf +
   xhro`s dry.]
   1. (Zool.) A small hemipterous insect (Phylloxera
      vastatrix) allied to the aphids. It attacks the roots and
      leaves of the grapevine, doing great damage, especially in
      Europe.
      [1913 Webster]

   Note: It exists in several forms, some of which are winged,
         other wingless. One form produces galls on the leaves
         and twigs, another affects the roots, causing galls or
         swellings, and often killing the vine.
         [1913 Webster]

   2. The diseased condition of a vine caused by the insect just
      described.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Phylloxera
    n 1: type genus of the Phylloxeridae: plant lice [syn:
         Phylloxera, genus Phylloxera]