ICHNEUMON-FLIES, PART 2\ EPHIALTINAE 363 



Fourteen species have been described in the genus Delomerista 

 Foerster, a Holarctic genus of northern distribution. Three of them 

 occur in the Nearctic region. In this paper three new Nearctic 

 species are described and D. diprionis, the commonest Nearctic species, 

 becomes a synonym. 



Delomerista species seem to be predominantly parasitic on sawflies 

 of the family Diprionidae. However, there are a number of early 

 references 3 to Nearctic species reared from lepidopterous hosts and 

 even from Mononychus vulpeculus (Fabricius), a weevil. A European 

 species, Delomerista pfankuchi, has also been recorded from a species 

 of Lepidoptera, Gelechia tragicella Heyden. 4 It is unwise to disregard 

 these records or to assume that they are wrong, since in the Nearctic 

 region diprionis is the only species of Delomerista for which there are 

 authentic host records of recent date. 



Because of insufficient biological data and especially the lack of 

 host records for the specimens available for study, several taxonomic 

 problems remain unsolved. These problems will be discussed further 

 under the species involved. 



I wish to thank the following for the loan of material: G. Stuart 

 Walley, and Lois Smith (formerly of University of Wisconsin), 

 Division of Entomology, Canadian Department of Agriculture, 

 Ottawa, Ont. ; H. K. Townes, University of Michigan, Ann Arbor, 

 Mich. ; and R. C. Brown (formerly of Northeast Forest Insects Lab- 

 oratory), New Haven, Conn. I am grateful to J. F. Perkins, British 

 Museum (Natural History), London, for the gift of several Delomerista 

 specimens. 



The figures were drawn by Arthur D. Cushman. 



Delomerista is one of the many genera established by Foerster 

 without included species. In his handwritten manuscript he desig- 

 nated Pimpla mandibularis Gravenhorst as type of Delomerista. For 

 some reason, perhaps because many of the species he had selected as 

 types of his new genera were undescribed, he did not include the 

 type species when he had the manuscript published. It is fortunate 

 that the present genotype is Foerster's unpublished selection. 



Foerster included Delomerista in his family Pimploidae. Later it 

 was usually considered a subgenus or synonym of Pimpla and placed 

 in the Pimplini. Then Hellen (1915, Acta Soc. Fauna Flora Fennica, 

 vol. 40, pt. 6, pp. 15-17 and 48) placed the genus in the "subtribe 

 Delomeristini, tribe Pimplides." More recently the genus has been 

 placed in the Ephialtini 5 and considered closely related to Perithous. 



* Riley and Howard, 1891, Insect life, vol. 3, p. 461.- Dimmock, 1898, Proc. Ent. Soc. Washington, vol. 4, 

 p. 154. 



4 Schutze and Roman, 1931, Isls budissima, vol. 12, p. 5. 



» Tbis Is the same as Pimplini of H. K. Townes. While I agree that priority strictly followed would 

 enable each of us to solve most of the nomenclatural problems which arise, I am following the rules, opinions, 

 etc., of the International Commission on Zoological Nomenclature. 



