Regal Fritillary
Speyeria idalia (Drury)

Status: State Endangered (August 1, 1989).

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

Aid to ID: 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.

Management Considerations: 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.

The content for this page was originally presented in the Endangered and Threatened Invertebrates of Wisconsin, a free publication available by contacting the Endangered Resources Program.