ENDANGERED SPECIES
Status: State Rare
Candidate for Federal Listing

REGAL FRITILLARY
(Speyeria idalia)

Description

This species' wingspan ranges from 2.9 to 3.8 inches (7.4 to 9.7 cm.). The regal fritillary is easily recognized by its large
size compared with other butterflies, reddish-orange forewings and black hindwings with two rows of spots. Both rows of
spots are white in females while the outer row is rust-orange in males.

Distribution

The historical range of Speyeria idalia extended from the Maritime Provinces of Canada south through the New England
states to North Carolina and west across the northern half of the U. S. to eastern Colorado and Montana. The species no
longer occurs in the Maritimes or much of New England and is rapidly declining in most of its remaining range except the
prairie states. In South Dakota, the regal fritillary is found in remnant prairie sites throughout the state.

Habitat: The regal fritillary generally inhabits wet meadows and tallgrass prairie, but the species also frequents dry undisturbed prairie areas in western South Dakota.

Natural History

Life Cycle: The regal fritillary population size seems to fluctuate. In some years individuals will be abundant and will scatter more widely while in other years, they are scarce. There is a single annual generation in this species. In South Dakota the first males appear in mid-June and fly until August, while the females flight period is early July to mid-September. The light brown eggs are laid near violets. After hatching, the unfed caterpillars over-winter beneath leaves on the ground. In spring, as temperatures rise, the larvae begin feeding on the leaves of violets. They are nocturnal feeders, staying hidden during the day. Mature larvae are velvety black with dull yellow to reddish orange stripes and six rows of tapering, fleshy spines. When full grown, the caterpillars shed their skin and form a light brown chrysalis with black spots. About two weeks later, the chrysalis splits open and the adult emerges.

Behavior: Males patrol throughout the day in search of emerging females. Females become more active and wander more extensively in late summer, when they search for areas to lay their eggs.

Adult Nectar Sources: Adults sip nectar at milkweeds and thistles. Whorled milkweed was noted to be the favored nectar source near Oahe Dam in 1983. Blazing stars also are flowers that attract regal fritillaries.

Larval Host Plants: Larvae feed on violets, including prairie violet. Nuttall's violet is presumed to be the host plant in western South Dakota.

Significance

Butterflies pollinate flowers and fill important roles in the food chain as food for spiders and birds. Owing to their
sensitivity to environmental changes, butterflies are used as indicator species. Many people enjoy watching and
photographing butterflies.

Conservation Measures

Regal fritillary populations have declined in the Midwest mainly due to the conversion of tallgrass prairies into cropland.
Pesticides have also contributed to the species' decline. Large tracts of native prairie with abundant wildflowers are needed
to protect this beautiful butterfly. One such area is the Samuel Ordway Prairie near Leola, S.D., managed by The Nature
Conservancy. The regal fritillary is a candidate for listing as a federally threatened species. Currently, South Dakota does
not have any invertebrate species listed as threatened or endangered.

Glossary

Chrysalis - inactive stage of butterflies in which the larva transforms into the adult form; pupa.
Larvae - the immature, wingless, and often worm-like form in which certain insects hatch from the egg, and in which they remain, with increase in size and other minor changes, until they enter the chrysalis stage. Butterfly and moth larvae are also known as caterpillars. Singular: larva.
Maritime Provinces - Canadian provinces; New Brunswick, Nova Scotia, and Prince Edward Island.
Nectar - a sweet liquid secreted by certain glands of a plant.
Nocturnal - moving about at night.

References


Ferris, C. and F. Brown. 1981. Butterflies of the Rocky Mountain States. U. of Okla. Press, Norman, OK.
Mitchell, R. and H. Zim. 1987. Golden Guide: Butterflies And Moths. Golden Press, New York.
Opler, P. A., and G. O. Krizek. 1984. Butterflies East of the Great Plains: An Illustrated Natural History. Johns Hopkins
University Press, Baltimore.
Pyle, R. M. 1981. The Audubon Society Field Guide to N. Am. butterflies. A. A. Knopf, New York.
Pyle, R. M. 1984. The Audubon Society Handbook For Butterfly Watchers. Scribner's Sons, New York.
Royer, R. 1988. Butterflies of N. Dakota: An Atlas And Guide. Minot State Univ. Science Mono. No. 1.
Van Bruggen, T. 1983. Wildflowers, Grasses And Other Plants Of The Northern Plains and Black Hills. Badlands Natural
History Association, Interior, SD.

Written by:
Gary Marrone, HCR-33, Box 4C, Ft. Pierre, SD 57532. 1992.

Illustrated by:
Ron Royer, Burlington, North Dakota 58722. Drawing was computer generated.

Reviewed by:
Dr. Robert Dana, Minnesota DNR, St. Paul, MN 55155.

Publication of the Regal Fritillary fact sheet was funded by the Prairie Pothole Joint Venture of the North American
Waterfowl Management Plan.