E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

The name Erynnis is derived from the Erinnyes or Furies who harried wrongdoers (Emmet 1991). Schrank used the generic name for all skippers, and used it to describe the erratic flight characteristic of skippers, as though they were avoiding the Furies. The Erinnyes sprang from the dark, thus the common name "duskywings" in reference to the dark wings. Scudder (1889b) was the first to use the name "duskywings" for the genus.

This and the remaining genera of the Pyrginae have rounded forewing tips, short discal cells, inconspicuous antennal tips, and porrect palpi. The genus Erynnis is distinguished by the mottled black background of the wings, hence the common name "duskywings". This Holarctic genus contains 17 Nearctic and 5 Palearctic species. Five species are found in BC. Closely related genera are all Neotropical. The larvae of this genus have been recorded as feeding on Quercus, Salix, Populus, Ceanothus, and Fabaceae. The various BC species cover this wide range of foodplant preferences, but individual species are restricted to one or a few closely related foodplants. Burns (1964) wrote the definitive work on the genus. Reference to Lindsey et al. (1931) is necessary for drawings of male genitalia, the only reliable structures for distinguishing most species. The shape of the left valve is the critical characteristic.

In BC E. propertius has historically been collected only on the southeastern tip of Vancouver Island and the adjacent Gulf Islands where Garry oak is known to occur. There is a single record from the 1930s of the species at the disjunct Garry oak population on Sumas Mountain, and numerous specimens from "Vedder Crossing," presumably the Sumas Mountain site. There are three records of the species from Lower Mainland localities, where botanists have so far not recorded Garry oak (Ross Lake, Hope, and 24 km north of Mt. Currie). Until either Garry oak can be found in these areas or an alternative foodplant can be shown for E. propertius, these specimens must be considered strays. All of the disjunct specimens were recorded late in the flight period, indicating that they were strays. Both Garry oak as the larval foodplant and nectar sources to sustain the long adult flight are equally important for maintaining the species. In addition, leaf litter must be left at the base of horticultural trees to protect the larvae during hibernation.

The species is found along the entire Pacific coast of North America from southern Vancouver Island to northern Baja California, in association with oak species.