REGAL FRITILLARY - Speyeria idalia
The regal fritillary is a large butterfly with reddish-orange forewings. The hindwings are black with white spots. They live in prairies and feed on milkweeds, thistles, clover and other flowers. This butterfly is characteristic of tallgrass prairies and the loss of tallgrass prairie habitat caused their populations to decline. The species is listed WATCH LIST by the Missouri Department of Conservation.
Identification
Regal fritillaries have large reddish-orange forewings with black and white spots. The hindwings are blackish-gray with white spots. Other species of fritillary butterflies have similar color patterns and may be confused with the regal fritillary. This species is quite large, with a wingspan that reaches two inches.
The regal fritillary caterpillar is deep orange with a velvet black appearance, sometimes with dull-orange spots. The chrysalis is brown and yellow with pink-brown wing cases. The entire chrysalis has scattered dark-brown patches.
For a technical description of this animal, refer to:
Paul A. Opler and George O. Krizek. 1984. Butterflies East of the Great Plains. Johns Hopkins University Press. Baltimore, Maryland. 294 pp.
Life History
The life history of this insect is the same as other insects with complete metamorphosis. Eggs hatch into caterpillars, which feed on plants, grow and molt several times. When they have stored enough body fat the caterpillars molt into the pupal stage (chrysalis). After several weeks or months they emerge as adult butterflies.
In late summer fertilized females search the tallgrass prairie for violet populations. Violets are not actively growing in late summer when the eggs are laid, so the female butterfly drops to the ground every 30 yards or so to deposit eggs on various drying prairie plants. Their activity appears random, but violets are the only acceptable larval host.
Eggs lay dormant in the vegetation through the winter and hatch in early spring when the violets begin to grow. It is not easy to find the young caterpillars as they generally feed at night to avoid predators. They grow very quickly if violets are abundant, then pupate in the prairie vegetation. After several weeks the adult butterflies emerge, the only "crop" of butterflies that season.
Adults feed on nectar from milkweeds, thistles, clover and other prairie flowers. Males emerge a week or more earlier than females. The main male flight is from mid-June to mid-July. The female flight is from early July to mid-August.
During mid-summer males are active in late morning and early afternoon. They can be seen searching for females. Their flight is low and steady.
Females perch on top of plants in open areas. Mated pairs can be seen fluttering across the prairie; usually the female is carrying a motionless male. The male remains attached to the female to make sure she is not fertilized by other competing males.
As summer progresses the female fritillary becomes more active and wanders in search of egg laying sites. They leave behind eggs that hatch next spring to start a new generation of regal fritillaries. Adult butterflies probably live a few weeks, certainly not after the first hard freeze.
Habitat and Distribution
Regal fritillaries belong to a group of butterflies that have been present in North America since long before the Ice Age.
Regal fritillaries formerly occurred from the Maritime Provinces south in the Piedmont and Appalachians to North Carolina, and westward across the northern half of the United States to eastern Colorado and Montana. This species seems to have declined rapidly. It is found only in the few remaining untilled areas in the prairie states. In Missouri it once occurred nearly statewide, but now is locally abundant in those few remaining prairie remnants.
This butterfly lives in prairies in the Midwest, while damp meadows or pastures with boggy or marshy areas were frequently used in the eastern United States.
Cause of Historic Decline
The main cause for the decline of the regal fritillary is the loss of tallgrass prairie habitat. Nearly 99 percent of Missouri's original 18 million acres of tallgrass prairie have been converted to other uses. Remaining populations are vulnerable to insecticide use at or near these prairie remnants.
Current Threats to Regal Fritillary
- Loss of habitat One-fourth of Missouri was once covered by prairie, but today only small remnants of the tallgrass prairie remain. Loss of prairie habitat is still the greatest threat to our current populations.
- Lack of Habitat Management Fires once controlled woody vegetation in prairie grasslands, but today, many prairies have become overgrown with shrubs and trees. Lack of fire management or other grassland management practices affect current populations of regal fritillaries. A grassland that is not properly managed eventually becomes unacceptable for these butterflies.
- Insecticides and Herbicides Insecticides are designed to kill insects, which include butterflies. No one is intentionally spraying for regal fritillaries, but they can be affected by pesticides targeting insect pests. There is little if any reason to control insect pests on prairie remnants so this is not presently a threat for most populations. Herbicides kill violets—the host plant for the fritillary caterpillar—and the prairie flowers that provide nectar for the adults. Herbicides should be used sparingly on prairie remnants. They should always be used according to the label and only to address threats from noxious weeds.
- Butterfly Collecting Butterfly collecting is a popular growing pastime. For many species removing a few adults does not threaten the populations. Collecting rare butterflies that are only locally abundant, however, can affect the populations. The Department does not allow regal fritillary collection on public prairies and encourages private landowners to prevent collecting.
Steps Toward Recovery
- Habitat improvement Protect existing prairie grasslands on private land and manage them for grassland benefits. Haying and grazing can both be acceptable grassland management strategies. If the grassland is maintained many kinds of prairie wildlife will benefit. Prescribed burning is also a good prairie management tool, though the timing of burning should be selected carefully. Expand prairies with the help of natural resource agencies by planting native grasses and wildflower mixtures. You may wish to plant flowers that provide good nectar sources for adult butterflies. Lists of these plant species are available from the Department of Conservation. If you have grasslands you may want to increase diversity by planting violets.
- Use pesticides sparingly Butterflies are sensitive to chemicals. Use pesticides only to deal with real pest problems and consider integrated pest management strategies with the help of the Department of Agriculture. If pesticide use is necessary, read and follow the label directions.
- Prevent Unnecessary Collecting Discourage people from collecting butterflies, particularly rare species. Encourage collectors and family members to enjoy butterflies alive in gardens and fields. If students want to collect a few specimens for a collection, collect them late in the season after the females have laid eggs.
Written by Charlene M. Bessken
Missouri and federal law prohibits the importation, transportation, sale, purchase, taking or possession of animals and insects on the State or Federal lists.
For more information on the regal fritillary, or to report sightings of this species, contact:
Endangered Species Coordinator or Wildlife Ecologist Missouri Department of Conservation Natural History Division P.O. Box 180 Jefferson City, MO 65102 573/751-4115
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