ˈfrit-fly A small fly of the genus Oscinis, destructive to wheat. 1881E. A. Ormerod Injur. Insects (1890) 92 The Frit Fly is a small, black, shining, two-winged fly.1893Jrnl. R. Agric.Soc. Dec. 827 Some other pests..are wire-worms, crane-fly, frit-fly..and winter-moth.