Fritillaries: regal fritillary (Speyeria idalia)

(Lepidoptera: Nymphalidae: Argynninae)

Profile prepared by Mace Vaughan and Matthew Shepherd, The Xerces Society for Invertebrate Conservation

The regal fritillary is found in the Great Plains states from eastern Montana east across the northern U.S. to Maine. However, it is very rare or at best locally frequent in its entire range. It is restricted to tall-grass prairie remnants and is rare or absent from former range east of the Appalachians. It has been recorded in southern Ontario and Manitoba, but probably does not have permanent colonies in Canada.

red list profile

conservation status

Xerces Red List Status: Vulnerable
Other Rankings:

Canada – Species at Risk Act: None
Canada – provincial status: None
Mexico: N/A
USA – Endangered Species Act: None
USA – state status: MI, NY, OH, WI: Endangered
IL: Threatened
IA, MN, MO, OK, PA: Species of Concern
NatureServe: G3
IUCN Red List: N/A

The regal fritillary is very rare or, at best, locally frequent throughout its range. It cannot be considered secure despite the number of extant populations (maybe more than one hundred) because of recent declines and in particular a range contraction of approximately 30 percent of its historic range. This butterfly has almost disappeared from its range east of the Mississippi. It is imperiled in five states (Illinois, Indiana, Pennsylvania, Virginia, and Wisconsin) and probably extirpated in a further fifteen.

Although the regal fritillary does not have federal listing status, it is listed as endangered under state legislation in Michigan, New York, Ohio, and Wisconsin, as threatened in Illinois, and as a species of concern in five more states. (A tally of state listings exceeded by only one other non-federally listed butterfly, the frosted elfin, Callophrys irus. See Red List profile for more information on this butterfly.)

description and taxonomic status

The regal fritillary is a large and beautiful butterfly in the family Nymphalidae (brushfooted butterflies). It has a wingspan of 67 to 105 mm (2⅝ to 4⅛ inches).

The upperside of the forewing is bright red-orange with black markings. On females the forewing is edged with a black marginal band with a postmedian row of white spots. The upperside of the hindwing is black with a postmedian row of white spots. There is also a submarginal row of spots that is orange on males and white on females. The underside of the forewing is orange with a marginal band of white spots and a black fringe. The hindwing is dark greenish brown with elongate white spots.

Larvae are yellowish-brown with yellow lines and black spots.

Speyeria idalia (Drury), 1773. Recent work (Williams 2002) has indicated that there may be two subspecies, S. i. occidentalis in the western part of the range and S. i. idalia in the east. However, only a handful of idalia specimens are known and the collapse in the eastern populations of regal fritillary may preclude further studies.

life history

Habitat of the regal fritillary is tall- grass prairie and other open, sunny locations, including meadows, marshes, and mountain pastures. Larval hostplants are violets. A wide range of violets are used, including birdfoot violet (Viola pedata) and prairie violet (Viola pedatifida) in the western parts of its range.

Eggs are laid on dead leaves and pebbles by females walking through the vegetation. They are laid singly on various plants even if there is no evidence of hostplants. A female may lay more than 2,000 eggs. Caterpillars hatch and overwinter without feeding. In spring they eat leaves of the violets.

There is one flight period from mid-June to mid-August.

distribution

The regal fritillary is found in the Great Plains states from eastern Montana east across the northern U.S. to Maine. However, it is very rare or at best locally frequent in its entire range. It is restricted to tall- grass prairie remnants and is rare or absent from former range east of the Appalachians. It has been recorded in southern Ontario and Manitoba, but probably does not have permanent colonies in Canada.


Courtesy of Butterflies and Moths of North America, Big Sky Institute.

threats and conservation needs

Threats

The biggest threat to the regal fritillary is loss of its prairie habitat to development and agriculture. In addition, many remaining prairie fragments are inappropriately managed for the butterfly, especially by ill-timed burns.

Conservation needs

The principal need is for its prairie habitat to be protected and appropriately managed. In addition to development or conversion of grasslands to agriculture, remaining prairie has been affected by pesticide use and fire (usually excessive prescribed burning) in ways that impact butterfly populations.

A better understanding of the impact of fire (prescribed burning) on butterfly populations is necessary. Further genetic and morphological studies maybe needed to determine if there are two subspecies.

references

Opler, P. A., and G. O. Krizek. 1984. Butterflies East of the Great Plains. Johns Hopkins University Press, Baltimore, MD.

Opler, P. A., and V. Malikul. 1992. A Field Guide to Eastern Butterflies. Peterson Field Guide #4. Houghton-Mifflin Co., Boston, MA.

Scott, J. A. 1986. The Butterflies of North America. Stanford University Press, Stanford, CA.

Tilden, J. W. 1986. A Field Guide to Western Butterflies. Houghton-Mifflin Co., Boston, MA.

Williams, B.E. 2002. Recognition of western populations of Speyeria idalia (Nymphalidae) as a new subspecies. Journal of the Lepidopterists’ Society 55(4):144-149.

additional resources

Big Sky Institute, Butterflies and Moths of North America: regal fritillary (Accessed 1/21/09)

Neartica; The Butterflies and Skippers of North America: regal fritillary (Accessed 4/30/05)

NatureServe Explorer. (Accessed 9/23/08)

Canadian Biodiversity Information Facility; regal fritillary (Accessed 4/30/05)

Missouri Department of Conservation; Endangered Species Guidesheet: regal fritillary (Accessed 9/23/08)

Pennsylvania Department of Conservation and Natural Resources; Wild Resource Conservation Program: regal fritillary (Accessed 4/30/05)

Wisconsin Department of Natural Resources; regal fritillary (Accessed 4/30/05)

Great Plains Nature Center; regal fritillary (Accessed 4/30/05)

citation

Vaughan, D. M., and M. D. Shepherd. 2005. Species Profile: Speyeria idalia. In Shepherd, M. D., D. M. Vaughan, and S. H. Black (Eds). Red List of Pollinator Insects of North America. CD-ROM Version 1 (May 2005). Portland, OR: The Xerces Society for Invertebrate Conservation.

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