The Collaborative International Dictionary of English v.0.48:

Wheatworm \Wheat"worm`\, n.
   A small nematode worm (Tylenchus tritici, formerly
   Anguillula tritici) which attacks wheat, advancing through
   the stem to the grains in the ear. In wheat affected with
   smut, each of the diseased grains may contain a large number
   of the minute young of the worm.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

wheatworm
    n 1: small roundworm parasitic on wheat [syn: wheatworm,
         wheat eel, wheat eelworm, Tylenchus tritici]