Published host associations are assessed for Leluthia astigma (Ashmead), Leluthia floridensis Marsh, and Leluthia mexicana Cameron, the three known species of Leluthia Cameron in the Nearctic Region. Leluthia astigma is reported as a parasitoid of Agrilus planipennis Fairmaire, emerald ash borer (EAB), infesting Fraxinus americana L., white ash, in Delaware County, Ohio. It is the first species of Leluthia for which a determined species of Agrilus Curtis has been confirmed as a host and the association vouchered. All other hosts reported in the literature for L. astigma require confirmation through rearing from an isolated host or documentation of an unequivocal host-parasitoid association. Leluthia astigma adults reared from parasitoid cocoons collected in Delaware County, Ohio parasitized and produced F₁ adults in the laboratory on last-instar EAB larvae collected in Ingham County, Michigan. Parasitism of EAB and other natural history data are reported for L. astigma, including the first records of L. astigma from Kansas and New York.