Erynnis persius
A duskywing skipper butterfly whose eastern subspecies is dependent on Wild Lupine as its sole larval host. The eastern population (subspecies persius) is in severe decline and is extirpated from Ontario, where habitat loss, lupine decline, and pesticide spraying eliminated the last populations. The western subspecies remains more secure.
Seasonal Activity
Diet
Lupine and other legume foliage (larva); flower nectar (adult)
Lifecycle
One generation per year. Mature larvae hibernate through winter and pupate between April and June. Adults emerge in late spring. Males search for females by perching on the ground or low vegetation. Females deposit eggs on host plant foliage. The eastern subspecies (E. p. persius) is entirely dependent on Wild Lupine and is extirpated from Ontario. The western subspecies uses a broader range of legumes including Thermopsis and Lotus.
Ecology
Host Plants
Native Habitats
Details
Description
The Persius Duskywing (Erynnis persius) is a medium-sized spread-winged skipper in the family Hesperiidae. The upper wing surfaces of both forewings and hindwings are dark brown, with the forewing bearing clear spots and dim markings with a grey patch at the end of the cell. Males have raised white hairs on the forewings. The hindwings are fringed with darker brown to black with a creamy white outer fringe. The species is difficult to distinguish from other duskywing skippers in the field. Larvae are light green with a reddish cast and covered in fine, short hairs, with a brownish-black head.
Globally, the full species is ranked as Secure (G5), but this masks a stark geographic divide. The widespread western subspecies is relatively stable, using a variety of legume hosts. The eastern subspecies (Erynnis persius persius) is in severe decline, listed as endangered in Connecticut, Minnesota, Ohio, New York, and New Hampshire, and threatened in Michigan. It is listed as endangered under Canada's Species at Risk Act and is considered extirpated from Ontario.
Lifecycle
A single generation is produced annually. Mature larvae overwinter through the winter months and pupate between April and June. Adults emerge in late spring. Unlike the Mottled Duskywing (Erynnis martialis), which engages in hilltopping behaviour, male Persius Duskywings seek females by perching on the ground or on low vegetation near host plants.
Females deposit eggs on host plant foliage. After hatching, larvae feed on the leaves and construct silk leaf-nests for shelter, a behaviour characteristic of the genus. The eastern subspecies is entirely dependent on Wild Lupine (Lupinus perennis), while western populations use a broader range of legumes including golden banner (Thermopsis) and trefoil (Lotus). Adults feed on flower nectar from a variety of spring-blooming plants.
Ecology
The eastern subspecies' ecology is defined by its dependency on Wild Lupine. As with the Karner Blue and Frosted Elfin, the Persius Duskywing's decline is directly attributable to the same forces driving lupine decline: habitat loss, fire suppression, habitat fragmentation, and the conversion of oak savannas and barrens to agriculture and urban development.
Pesticide spraying for Spongy Moth (Lymantria dispar) control has been an additional, significant threat — broad-spectrum insecticides applied during the larval period cause direct mortality. The species is part of a distinctive suite of oak savanna Lepidoptera — alongside the Karner Blue, Frosted Elfin, and Mottled Duskywing — that have experienced catastrophic range-wide declines. Of these, only the Mottled Duskywing still persists in Ontario.
Host Plants
Eastern subspecies larvae feed exclusively on Fabaceae:
- Wild Lupine (Lupinus perennis) — primary host for eastern subspecies E. p. persius
Western subspecies use additional legumes including Thermopsis (golden banner) and Lotus (trefoil).
Habitat
The eastern subspecies is associated with oak savannas, pine barrens, and open sandy habitats where Wild Lupine occurs. These fire-dependent ecosystems have been reduced to a fraction of their historic extent. Western populations occupy a broader range of open habitats including foothills, meadows, and woodland clearings throughout the western United States and Canada, from Alaska to Arizona.