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Regal Fritillary (Speyeria idalia)



Regal fritillary (Speyeria idalia), a butterfly presently listed as a Federal Species of Concern and Endangered in Wisconsin, has been found in large grassland areas with tallgrass prairie remnants or lightly grazed pasture lands containing prairie vegetation. The larval food plants are violets, primarily prairie violet (Viola pedatifida), birdsfoot violet (V. pedata) and arrowleaf violet (V.sagittata). Adults are present between late June and early September with peak flight usually the first part of July.

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - both state and federal - and the rank (S and G Ranks) for Regal Fritillary (Speyeria idalia). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where occurrences of this species meet NHI data standards and is not meant as a comprehensive map of all observations.

Note: Species recently added to the NHI Working List may temporarily have blank occurrence maps.

Documented locations of Speyeria idalia in the Natural Heritage Inventory Database as of July 2015.
Summary Information
State StatusEND
Federal Status in WisconsinSOC
State RankS1
Global RankG3
Tracked by NHIY

Species guidance

Note: a species guidance document is not available at this time. Information below was compiled from publication PUB-ER-085-99 (now out-of-print).

Identification: Regals are large butterflies with orange background on the forewings and dark background on the hindwings. The thick black marginal area on the upperside of the wings contains orange spots (male) or white spots (female). The underside of the hindwings shows the large silver spots typical of many fritillary butterflies. However, the background is evenly dark or rusty red without a lighter marginal band on the lower hindwing. Only one other fritillary species shows this ventral wing pattern but its upper surface lacks the dark marginal areas of the regal. The adult wingspan is about 2.75-3.50 inches (7.1-9.0 cm).

Habitat: Large grassland areas with prairie remnants or lightly grazed pasture lands containing prairie vegetation where topography often includes hills and valleys, are habitats used by regals in Wisconsin. The larval food plants are violets, primarily prairie violet (Viola pedatifida), birdsfoot violet (V. pedata) and arrowleaf violet (V.sagittata). Regals are strong fliers and appear to require large areas to support a population though area size depends on availability of quality habitat that will vary according to local vegetation and management.

State Distribution: Occurs in Crawford, Columbia, Green, Iowa, Portage, and St. Croix Counties.

Phenology: Adults are present between late June and early September with peak flight usually the first part of July. Mating takes place before August first. Oviposition occurs near violets during August and September. The newly hatched larvae seek shelter in or under the leaf litter and immediately go into diapause. The following spring when temperatures rise, the larvae begin to feed at night on the violet leaves until pupation in early summer.

Management Guidelines: Survival of regal fritillaries in Wisconsin will depend on protection and enhancement of large areas of suitable grassland habitat. Habitat fragmentation and loss of prairie communities to development and intensive agriculture contribute to the decline of the species. Grassland management activities must be adjusted where regals are established in order to maintain the populations. Sites that experience frequent controlled burns (less than 5-7 year rotation) exhibit reduced numbers of butterflies therefore burn management should be avoided on regal sites. Light grazing, infrequent mowing and/or localized brush cutting are positively associated with regal abundance on sites in Wisconsin.



Regal Fritillary

Important populations of the globally rare regal fritillary (WI Endangered) inhabit prairies in the Southwest Savanna.

Photo © Mike Reese.

Regal Fritillary

The WI Endangered regal fritillary, a globally rare prairie butterfly, is shown here nectaring on orange milkweed.

Photo © Ann Swengel.

Regal Fritillary

Regal Fritillary, above - Muralt Bluff Prairie State Natural Area, Green County.

Photo © Mike Reese.

Regal Fritillary

Female Regal Fritillary nectaring on rough blazing star.

Photo © Ann Swengel.

Regal Fritillary

Male regal fritillary.

Photo by W.A. Smith, WDNR.

Regal Fritillary

Photo © Ann Swengel.

Last revised: Wednesday, November 07, 2018