Frosted Elfin
FWS Focus

Overview

The frosted elfin was originally described as Polyommatus irus by Jean-Baptiste Godart in 1824, (Johnson 1991, p. 153). The current name is Callophrys irus, and it was previously assigned to the genus Incisalia (Scudder). The similar looking Henry’s elfin (C. henrici) was not described until 1867 (Grote and Robinson 1867, p. 174-176) and was often confused with C. irus in earlier literature (Cook 1907, p. 181-187; Calhoun 2004, p. 144). Three frosted elfin subspecies have been described (and generally accepted) and these have regional distributions: C. i. hadros (originally described as I. hadros in Cook and Watson 1909, p. 181) is confined to the southwestern states of Texas, Louisiana, west Arkansas, and Oklahoma; C. i. arsace (originally described in Boisduval and Le Conte 1829-[1837], p. 103-104) occurs along the Atlantic Coast with some scientific disagreement about whether it occurs just in South Carolina (Gatrelle 1991, p. 57) or also north into southern New England (Shepherd 2005, p. 3); and C. i. irus that occupies the remainder of the inland areas from Florida north to New England and New York (and historically, southern Ontario), through Ohio and Michigan to Wisconsin with scattered populations also farther southeast, including eastern Maryland (Committee of the Status of Endangered Wildlife in Canada [COSEWIC] 2000, p. 3; Shepherd 2005, p. 2; Schweitzer et al. 2011, p. 161).

Characteristics
Overview

The frosted elfin is a small, non-migratory butterfly that has experienced population declines across its historic range due to habitat loss. Frosted elfin depend upon pine barrens, a rare habitat type characterized by fire-dependent conifers, dense thickets of scrub oak, and grassy openings that support specialized plants like wild indigo and wild blue lupine — host plants frosted elfin larvae need to survive. 

In 2018, a team of scientists completed an interim Species Status Assessment for the frosted elfin, synthesizing the best available science from across the species' range to develop a clear picture of its current condition and needs. Equipped with information from the status assessment, the U.S. Fish and Wildlife Service is working proactively with states and other partners to develop and implement conservation efforts that support the needs of this butterfly.

Since 2019, the Service has been coordinating range-wide surveys in partnership with state agencies and nongovernmental organizations to see if they can find frosted elfin in any of the places where they were last seen. The Service will be reviewing the butterfly’s status in 2023 to determine whether or not it needs federal protection.

Scientific Name

Callophrys irus
Common Name
Frosted Elfin
FWS Category
Insects
Kingdom

Location in Taxonomic Tree

Identification Numbers

TSN:

Characteristics

Characteristic category

Habitat

Characteristics
Habitat

Frosted elfin and many other species — including whip-poor-will, eastern towhee, eastern hognose snake, and the federally endangered Karner blue butterfly — depend on pine barrens. This rare type of habitat is characterized by sandy soil, an overstory of fire-dependent conifers, and grassy openings that support plants like wild blue lupine and wild indigo. Frosted elfin lay their eggs on these two plants alone; their larvae need to feed on them to survive.

Grassland

Ecosystem with large, flat areas of grasses.

Characteristic category

Physical Characteristics

Characteristics
Color & Pattern

The upperside of the wings of frosted elfin are uniform dark gray brown in color. The underside of the wings is also largely gray brown, but variegated, with a dusting of pale scales on the outer edge of the hindwing, with a dark spot and an irregular dark line.

Allen, T.J. 1997. The butterflies of West Virginia. University of Pittsburgh Press, Pittsburgh, PA.

Size & Shape

Frosted elfin are small butterflies with short tails projecting from their hindwings.

Measurements

Wingspan: 0.87 to 1.42 inches (22 to 36 mm)

Schweitzer, D.F., M.C. Minno, and D.L. Wagner. 2011. Rare, declining, and poorly known butterflies and moths (Lepidoptera) of forests and woodlands in the Eastern United States. U.S. Forest Service. Forest Health Technology Enterprise Team, FHTET-2011-01. 517 pp.

Characteristic category

Lifecycle

Characteristics
Lifecycle

The entire lifecycle of a frosted elfin is completed within one year. Adults emerge in spring and lay eggs, eggs hatch into larvae that rely on specific host plants of wild lupine or wild indigo, larvae pupate by late July on or near host plants, and remain in this state until the following spring.

Geography

Characteristics
Range

The frosted elfin butterfly was once found from Florida west to Texas, and north to Ontario. Today, its range is uncertain. The species is now likely extirpated in Ontario, Canada, and the District of Columbia, Georgia, Illinois, and Vermont.

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