Endangered Resources Program Species Information
Bog Fritillary (Boloria eunomia)

Bog Fritillary Photo by Mike Reese. Check the photos tab for additional photos.
Photo © Mike Reese

Overview

Species Overview

Bog fritillary (Boloria eunomia), a State Special Concern butterfly, has been found in open acid bogs with Labrador tea (Ledum groenlandicum), leatherleaf (Chamaedaphne calyculata), bog laurel (Kalmia polifolia) and cranberry (Vaccinium spp.) with scattered black spruce and tamarack.. The bog fritillary has a short flight period of usually two weeks or less in Wisconsin from about June 12 through June 25. Flight has begun as early as 23 May 1977, an extraordinarily early season, and records in other years have extended into late June.

Status and NHI Documented Occurrences in Wisconsin

The table below provides information about the protected status (State and Federal Status) and the rank (S and G Ranks) for Bog Fritillary (Boloria eunomia). See the Working List Key for more information about the abbreviations used. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. For invertebrates, dots depict locations from the "Invertebrate Atlas," a database with occurrences of rare and common aquatic and select terrestrial invertebrate species found in Wisconsin and adjacent areas. While the invertebrate atlas is a quality assured database, not all records have been verified. The map is provided as a general reference of where this species has been found to date and is not meant as a range map.

Summary Information
State Status:	SC/N
Federal Status in Wisconsin:	none
State Rank:	S3
Global Rank:	G5
Tracked by NHI:	Y
Species of Greatest Conservation Need:

Documented locations of Boloria eunomia in the Natural Heritage Inventory Database as of April 2009.

Detailed Information

Identification: Wings are orange-brown with dark markings. The ground color of the hindwing below is orangish-brown with a tan postmedian band followed by a row of round silver spots. The submedian area consists almost completely of silver spots. The outer margin is lined with silver chevrons. Similarly-colored crescents (Phyciodes spp.) and checkerspots (Chlosyne spp.) in Wisconsin typically display more black scaling on the outer borders of the upper side of the wings than do the fritillaries, in which the black markings are most often broken into an array of discrete spots. The underside of the hindwing must be viewed to separate the species. Wingspan: 36-40mm. Length of forewing: 20-24 mm. All Boloria larvae have rows of branched spines with no mid-dorsal row and no spines on the head. Larvae are gray with fine white dots and the spines are pale pink or white.

Similar Species: The silver-bordered fritillary (Boloria selene) has fewer submedian silvery spots and a postmedian row of black spots on the hindwing below.

Habitat: Open acid bogs with Labrador tea (Ledum groenlandicum), leatherleaf (Chamaedaphne calyculata), bog laurel (Kalmia polifolia) and cranberry (Vaccinium spp.) with scattered black spruce and tamarack. Most abundant in moist/wet areas supporting dense cranberry, including floating mats.

Nectar Source: Adults visit Labrador tea (Ledum groenlandicum), goldenrod (Solidago spp.) and have been observed nectaring on bog laurel (Kalmia polifolia) in Michigan (Nielsen, 1999).

Host Plant: Females have been observed laying eggs on the stems of cranberry (Vaccinium oxycoccos) in Bayfield (Ferge 1994) and Forest Counties (Nekola 1996). Cranberry and creeping snowberry (Gaultheria hispidula) have been reported from Ontario. Elsewhere, the larvae are said to prefer leaves of shrubby willow (Salix spp.) and violet (Viola spp.).

Associated Species: At some sites, bog coppers (Lycaena epixanthe) may also be present later in the season.

State Distribution: Often quite localized, especially in larger sites. Can be abundant in the proper habitat at the proper time. Ashland, Bayfield, Chippewa, Douglas, Forest, Iron, Langlade, Marathon, Marinette, Oneida, Price, Rusk, Sawyer, and Vilas counties.

Global Distribution: Eurasia, Alaska and most of Canada south to the bordering United States including northern Maine and the northern Great Lakes region; south in the Rocky Mountains to Colorado.

Threats: Disruption of bog hydrology.

Phenology: The bog fritillary has a short flight period of usually two weeks or less in Wisconsin from about June 12 through June 25. Flight has begun as early as 23 May 1977, an extraordinarily early season, and records in other years have extended into late June.

Life History: Females deposit eggs in groups of 2 to 4 or even 20 eggs in a group (Scott 1986). Larvae feed only at night and the young larvae are gregarious. Winter is spent as late-stage larvae.

Survey Guidance: Like other boreal or alpine butterflies that live in frigid, windy climates, look for the adults flying low to the ground. On cool, cloudy days, adults perch low amongst the mosses and heaths. Males patrol during the day in open areas searching for females. New county records should be documented with voucher specimens.

Inventory, Monitoring and Research Needs: Locate additional populations. A considerable amount of potential habitat in Wisconsin has not been surveyed. There are likely a significant number of undiscovered populations throughout northern Wisconsin.

Information originally presented as part of the Online Field Guide to Rare Lepidoptera: Bogs and Barrens.

Photos

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