Eastern persius duskywing: COSEWIC assessment and status report: chapter 2

Species Information

The Persius Duskywing (Erynnis persius) is a small, dark butterfly with four tiny white spots on the forewings. It is in the group of butterflies known as skippers in the subfamily Pyrginae, within the family Hesperiidae. The species is presently separated into four described subspecies, one of which, the Eastern Persius Duskywing is the subject of this report.

Distribution

As presently recognized, the range of the Persius Duskywing extends from the north Atlantic states within the United States, westward to the Pacific Coast, north to the Yukon and south to California. The Eastern Persius Duskywing occupies the eastern portion of this range, from the north Atlantic states to the Great Lakes region. The subspecies’ known range in Canada is restricted to southwestern Ontario.

Habitat

Eastern Persius Duskywings are believed to be restricted to sites where the larval food plants, wild lupine and wild indigo, grow. Typically, they are found in open oak savannahs, pine barrens and prairies or other open, sunny locations, such as forest glades and road rights-of-way.

Biology

Adult Eastern Persius Duskywings fly from early May to early June in Canada. Eggs are laid singly on new leaves of wild lupines or wild indigo, and the caterpillars grow to maturity by July. The caterpillars enter diapause during the last instar and overwinter. The following spring they complete development and emerge as adults.

Population Sizes and Trends

The Eastern Persius Duskywing has declined in much of its range, and is widely considered to be rare. It is considered to be extirpated from Maine and has not been reported from Maryland, New Jersey or New York in the last twenty years. In Ontario, it was first collected in 1969 and was last reported in 1987. Provincial sources consider the Eastern Persius Duskywing to be extirpated in Ontario and therefore Canada.

Limiting Factors and Threats

It is believed that the Eastern Persius Duskywing has suffered from poor habitat management and habitat change, which resulted in sharp decreases and destruction of populations of host plants. Wild lupines and wild indigo are the only known host plants for the caterpillars of the Eastern Persius Duskywing. Natural succession of open woodland, fire suppression, and direct anthropogenic alterations of the habitat through resource extraction or tree-planting have adversely affected many areas that may have been occupied by this skipper in the past.

Special Significance of the Species

The Eastern Persius Duskywing is a lupine-feeder, like the Karner Blue and the Frosted Elfin. Together, these butterflies are representative of a rare and declining natural community within northeastern North America. Attention drawn to the Eastern Persius Duskywing and the other butterflies may aid in conserving the special animal and plant community of which they are a part.

Existing Protection or Other Status Designations

The Eastern Persius Duskywing is designated as Endangered in Indiana, New Hampshire, New York and Ohio; Threatened in Michigan and Massachusetts; and of Special Concern in Connecticut and Pennsylvania. It is considered to be extirpated from Maine. Provincial sources consider the Eastern Persius Duskywing to be extirpated in Ontario and therefore Canada. It is not specifically protected under any federal or provincial legislation in Canada.