PROC. ENTOMOL. SOC. WASH. 98(1), 1996, pp. 87-92 PTEROMALUS ELEVATUS (WALKER) (HYMENOPTERA: PTEROMALIDAE): NORTH AMERICAN RECORDS OF AN IMMIGRANT PARASITOID OF THE GALL FLY UROPHORA J ACE AN A (DIPTERA: TEPHRITIDAE) E. Richard Hoebeke and A. G. Wheeler, Jr. (ERH) Department of Entomology, Cornell University, Ithaca, New York 14853-0901, U.S.A.; (AGW) Bureau of Plant Industry, Pennsylvania Department of Agriculture, Har-risburg, Pennsylvania 17110, U.S.A. Abstract. — Pteromalus elevatus (Walker), a Palearctic species, is reported from several localities in Nova Scotia as a probable parasitoid of the gall-inducing tephritid Urophora jaceana (Hering) on black knapweed (Centaurea nigra). These records are only the third for P. elevatus in the New World; the first such record (Newfoundland), published in the European literature, has been overlooked by North American workers, and a collection of specimens in New Brunswick has been briefly noted in the American literature. This species is described and its distribution and habits in the Old World are summarized. Key Words: Insecta, Pteromalidae, parasitism, adventive insects, biological control, Te-phritidae As part of continuing surveys for immi-grant insects in the Canadian Maritime Provinces, we report here the collection of Pteromalus elevatus (Walker) (Hymenop-tera: Pteromalidae), a species widely dis-tributed in the western part of the Palearctic region and a known parasitoid of the knap-weed gall fly Urophora jaceana (Hering) (Diptera: Tephritidae). During the summers of 1993-1995, this pteromalid was taken at numerous sites in Nova Scotia by sweeping flowerheads of black knapweed (Centaurea nigra L.). This plant is a principal host of U. jaceana, also native to central and west-em Europe and accidentally introduced into eastern Canada (Foote et al. 1993). Although a North American record (Newfoundland) for P. elevatus was pub-lished by Graham (1969) in his monograph of the Pteromalidae of Northwestern Eu-rope, it was inadvertently omitted from the list of pteromalids in the Catalog of Hy-menoptera in America North of Mexico (Burks 1979). In addition, Peschken et al. (1982) reported that 3% of 580 U. cardui (L.) larvae from galls on Canada thistle (Cirsium arvense (L.) Scop.) at Sussex Cor-ner, New Brunswick, were parasitized by this pteromalid (as Habrocytus elevatus). The two literature records and our own col-lection records for P. elevatus in Nova Sco-tia are listed and mapped, together with a short description of the parasitoid and in-formation on its geographic distribution, hosts, natural history, and possible mode of introduction. Pteromalus elevatus (Walker) Eutelus elevatus Walker 1834: 366. Pteromalus elevatus: Walker 1848: 77, Boucek and Graham 1978a: 228, 1978b: 81. Habrocytus elevatus: Kurdjumov 1913: 13, Boucek 1965: 8, Graham 1969: 538. A complete synonymy for this species can be found in Graham (1969: 538-539), and Boucek and Graham (1978a: 81).