grass sawfly

from The Collaborative International Dictionary of English v.0.48

Wheat sawfly \Wheat sawfly\
   (a) A small European sawfly ({Cephus pygmaeus}) whose larva
       does great injury to wheat by boring in the stalks.
   (b) Any of several small American sawflies of the genus
       {Dolerus}, as {Dolerus sericeus} and {Dolerus arvensis},
       whose larvae injure the stems or heads of wheat.
   (c) {Pachynematus extensicornis}, whose larvae feed chiefly
       on the blades of wheat; -- called also {grass sawfly}.
       [Webster 1913 Suppl.]