Cecidomyia lamellata Gagne, new species, is described from adults of both sexes, pupae, and larvae taken from resin in branchlet swellings of baldcypress, Taxodium distichum (L.) Rich. (Taxodiaceae), in Fort Pierce, Florida. Some anatomical characters of the new species depart from the previously known limits of the genus. Baldcypress is the first known non-Pinaceae host of Cecidomyia.
