Distribution North America north of Mexico and central-eastern Asia (Sthenopis of authors, not Packard).
Systematics Evidence for monophyly not yet established. North American species are all distinct from other North American genera, but no uniquely shared features have yet been designated.Males have metatibial androconia. Larval stage is described for Sthenopis auratus by McCabe & Wagner (1989) and Leonard et al. (1992). Sthenopis of central Asia as listed by Nielsen et al (2000) are not defined with respect to species in North America. Sthenopis auratus (Grote, 1878) and Phassus eldorado Pfitzner, 1906 are junior and subjective synonymies of Sthenopis pretiosus (Herrich-Schäffer, ) (Mielke & Grehan, 2016)
Biology Early larval development is not recorded, but it is probable that the first and prehaps some later instars feed within the leaf litter zone before transition to root tunneling and feeding. First instart larvae of S. thule have been observed to consume detritus and moss leaves under laboratory conditions (JRG personal observtion).
Larvae of S. argenteomaculatus, S. purpurascens, and S. thule tunnel into tree or woody shrub roots and then extend tunnels into the lower host stem prior to emergence (Grehan, 1989; Vallée & Béique, 1979). The mature larva constructs an exit hole in the stem from where the adult emerges.
Larvae of S. pretiosus feed on the leaf base/rhizome of various ferns in the Polypodiaceae (McCabe & Wagner, 1989).
Emerged Sthenopis argenteomaculatus on speckled alder (Alnus incana)
Sthenopis purpurascens, North Dakota. Collected by Carl Barrentine. Image courtesy Gerald Fauske. Click image for details. Sthenopis pretiosus habitat. Jericho Research Forest, Vermont. Note young broadleaf forest with understory of ostrich fern (host of S. pretiosus)
References Gross, H.L. & Syme, P.D. 1981.Damage to aspen regeneration in northern Ontario by the ghost moth, Sthenopis quadriguttatus Grote. Canadian Forestry Service Research Notes 1 (4), 30-31. Leonard, J. G., J. R. Grehan, and B. L. Parker. 1992.First instar descriptions of Korscheltellus gracilis (Grote) and Sthenopis auratus (Grote) (Lepidoptera: Hepialidae) with a consideration of cladistic relationships between setae. Journal of the New York Entomological Society 100: 594-614. McCabe, T.L. & D.L. Wagner. 1989. The biology of Sthenopis auratus (Grote) (Lepidoptera: Hepialidae). Journal of the New York Entomological Society 97, 1-10. Mielke, C.G.C. & Grehan, J.R. 2016. Description of a new species of Phassus Walker, 1856 from Costa Rica, Pallas, gen. n., with a new species from Guatemala, and taxonomic notes on Sthenopis Packard,  (Lepidoptera, Hepialdiae). The European Entomologist 7, 113-134. Schmidt, B.E. & Lawrie, D.D. 1999. Notes on the genus Sthenopis. Journal of the Lepidopterist's Society 53, 127-129. Vallée, G. & Béique, R. 1979. Dégâts d'une hépiale et susceptibilité des peupliers. Phytoprotection 60, 23-30. English translation.