A spectacular large butterfly — black hindwings spotted in white and brilliant orange forewings. Specialist of native tallgrass prairie. Once common, now reduced to a handful of remnant grassland populations.
§ Quick facts
§ Encyclopedia
The regal fritillary is a striking nymphalid butterfly found among some of the remaining tallgrass and mixed-grass prairies in the east-central United States. This prairie-specialist butterfly has a characteristic deep orange color and unmistakable dark hindwings with two bands of spots. On the female, both bands of spots are white. However, on the male, the outer band of spots is orange in color. Females also tend to be slightly larger than males. The ventral surface of the hindwings is olive brown to black in color with bold silvery white spots. The wingspan of S. idalia usually measures 68–105 millimetres (2.7–4.1 in). Flight is in the summertime from approximately June to September and adults tend to be swift in flight, coasting close to the ground. It is listed as a species of special concern and believed extirpated in the US state of Connecticut.
Source: Wikipedia — Regal fritillary Licensed under CC BY-SA 4.0
§ Identification
Field marks. Large butterfly. Females: black-blue upper wings with cream spots; underside with silver spangles. Males: orange-and-black upper wings.
Similar species. Other fritillary species (different markings). Diana Fritillary (similar females; different range). Aphrodite Fritillary (orange males).
Voice. N/A
§ Diet & behavior
Diet. Adults: nectar from native prairie flowers (milkweed, butterfly weed, joe-pye weed). Caterpillars: violets (Viola pedatifida and other prairie violets).
Behavior. Among the most spectacular tallgrass prairie butterflies. Population has declined 99%+ across most of historical range due to prairie conversion to row crops. Survives in fragmented eastern populations (Pennsylvania, New Jersey) and central populations (Kansas, Missouri tallgrass prairie remnants). USFWS proposed for federal listing in 2024. Caterpillars overwinter as small first-instar individuals.
§ Range
Central US grasslands
§ Habitat
Tallgrass prairies, native grasslands
§ Threats
Tallgrass prairie loss to row crops, fire suppression, violet host plant loss, pesticide drift.
§ Conservation status
According to the IUCN Red List, the regal fritillary is currently classified as Near Threatened.
§ What helps
Support prairie restoration. Plant native violets. Donate to grassland conservation groups.
§ Further reading
- Wikipedia — Regal fritillary
- www.xerces.org — authoritative profile of Argynnis idalia
- iNaturalist · taxon 49294
- IUCN Red List — search for Argynnis idalia
- GBIF occurrence records
- Encyclopedia of Life — Argynnis idalia
§ Sources cited
- Xerces Society Regal Fritillary
- USFWS Species Status Assessment
- Kansas State University
- iNaturalist
