What is "cephus pygmaeus"

Wheat sawfly \Wheat sawfly\

1. A small European sawfly ( Cephus pygm[ae]us) whose larva does great injury to wheat by boring in the stalks.

2. Any of several small American sawflies of the genus Dolerus, as Dolerus sericeus and Dolerus arvensis, whose larv[ae] injure the stems or heads of wheat.

3. Pachynematus extensicornis, whose larv[ae] feed chiefly on the blades of wheat; -- called also grass sawfly.