Regal Fritillary

Endemic to tallgrass prairies in the United States.

WSU Vancouver

June 10, 2022

Geography

Range Map

Regal fritillary (Speyeria idalia) is closely tied to the tallgrass prairie ecosystem of the United States. The historic range of the butterfly is throughout the temperate prairies.

Current range

The current range of the fritillary has been drastically reduced, and within the Midwest-Plains population, there are many isolated metapopulation networks (groups of sites).

The eastern population is completely extirpated except for the Fort Indiantown Gap population in Pennsylvania.

Study Area

Our study sites are in Riley County, Kansas, Portage County, Wisconsin and Whiteside County, Illinois.

Natural History

Species interactions

Host Plant

Like other greater fritillaries, regal fritillaries consume violet (Viola spp.) leaves as a caterpillar.

Nectar Plants

They are nectar generalists, possibly favoring purple or pink flowers such as milkweeds (Asclepias spp.), thistles (Cirsium spp.), and beebalm (Monarda fistulosa).

Predators

As adults, regal fritillaries' predators include birds and spiders.

This invasive banded orb-weaver spider was spotted with a regal in its web in Hall County, Nebraska.

Habitat

Habitat for this species includes tallgrass prairie or damp areas in shortgrass prairie, meadows, or wet fields.

Population Dynamics

Due to the fragmented nature of the prairies in the United States, regal fritillaries now exist in metapopulation networks. However, researchers believe they also likely existed in metapopulation networks historically, moving to patches of more favorable habitat within the tallgrass.
There are very few sites left, and total population estimates they occur at less than 100 sites.
The butterflies are capable of dispersing across long distances, but appear to have barriers to movement such as continuous tree lines.
The eastern subspecies occurs only at a military base in Pennsylvania.

Life Cycle

01 / 05

Adults

In Illinois and Wisconsin, the butterflies emerge in June. Females are seen until September. In Kansas, butterflies can be seen beginning in May and females are last observed in October.

Courtship

Males patrol frequently for females, making them very visible in their habitat, and the fritillaries do courtship flights prior to mating.

Reproductive Diapause

Female regal fritillaries undergo a reproductive diapause (period of low activity) after emerging, mating, and nectaring. They rest for 2-3 weeks in shaded places to develop their eggs.

Eggs

Females lay eggs throughout the understory of prairie near where they can detect violets, but their egg-laying can be haphazard.

Caterpillars

Caterpillars hatch in the fall and immediately enter diapause without eating. They wake in the spring and consume violet leaves.

Conservation

Listing Status

Currently, they are considered vulnerable globally , and under review by the Fish and Wildlife for listing under the endangered species act. They are apparently secure in Kansas, but at risk throughout the rest of their range. They are a Species of Greatest Conservation Need in the majority of their range , including Kansas. They are likely extirpated from nearly half of the historic range.

Recovery Efforts

Wisconsin's Wildlife Action Plan

Wisconsin has a statewide action plan within which SGCN-categorized species are included. The intent of this plan is to define and implement conservation actions to benefit species of greatest conservation need.

According to the Wisconsin Department of Natural Resources, regal fritillary habitat benefits most from low-impact actions, such as conservation grazing, infrequent mowing, and manual removal of brush and woody encroachment. Where prescribed fire is applied more frequently than every 5-7 years, abundance of this butterfly was lower. Thus, fire is not a recommended method to manage regal habitat.

Illinois Wildlife Action Plan

Illinois Wildlife Action Plan has two campaigns to preserve and improve wildlife habitats that include regal fritillary habitat: Wetland Campaign , and Farmland and Prairie Campaign . However, these programs currently only target vertebrate species for conservation, like this blue-spotted salamander from Cook County, IL.

Population Trends

We analyzed eight sites where regal fritillaries are found. The sites had varying trends in abundance and phenology with no correlation between the two. A few of the sites had declines and advances as seen in our example.