Тhe agromyzid (Diptera: Schizophora: Agromyzidae) fauna of America north of Mexico is described in the first part of this publication, including a genus key and discussions on morphology, life history and classification. The second part is a species-level revision of the family in the “Delmarva” states of the United States of America, that is, of the District of Columbia and the surrounding states of Delaware, Maryland, Virginia and West Virginia. The fauna of this region includes 156 species.This study presents 346 new state and provincial records and 23 new country records, two of which are new continental records (Agromyza abiensZetterstedt andA. apfelbeckiStrobl).Liriomyza endiviaeHering is no longer considered to occur in North America. Fifteen species are newly described:Agromyza echinalissp. nov.,Melanagromyza brunkeisp. nov.,M. eoflacensissp. nov.,M. glyptossp. nov.,M. rutellasp. nov.,Ophiomyia capitoliasp. nov.,O. cupreasp. nov.,O. galiodessp. nov.,O. heleiossp. nov.,O. kaliasp. nov.,O. laticolissp. nov., Cerodontha (Poemyza) ungulasp. nov.,Phytomyza avicursasp. nov.,P. catenulasp. nov., andP. winklerisp. nov.Four new species-level synonyms and one genus-level synonym are provided:Agromyza marmorensisSpencersyn. nov.is included as a synonym ofA. aristataMalloch;Melanagromyza fastosaSpencer,syn. nov.is included as a junior synonym ofOphiomyia tiliae(Couden);Melanagromyza verbesinaeSpencer is considered a synonym ofM. vernonianaSteyskal;Phytomyza ranunculoidesSpencer,syn. nov.is included as a junior synonym ofPhytomyza loewiiHendel; the genusLiomycinaEnderlein,syn. nov.is included as a junior synonym ofPhytobiaLioy.Ophiomyia ultima(Spencer),comb. nov.is recombined fromMelanagromyza.Euhexomyza albiculaSpencer,stat. reinst.,comb. nov.is resurrected from synonymy withE. winnemanae(Malloch). New host records are given.
