Dingy Fritillary (Boloria improba [Butler])
Wing span: 1 1/8 - 1 3/8 inches (3 - 3.5 cm).
Identification: Small. Upperside dull orange-brown, darker at wing bases; markings faded and indistinct. Underside hindwing dark orange-brown at base, often grayish on outer half. Hindwing with ivory white costa and ivory dash between costa and cell.
Life history: Males patrol near the ground in the vicinity of host plants. Eggs are laid singly on stems of host plant; caterpillars eat leaves. Two years are required for development from egg to adult; newly hatched caterpillars hibernate the first winter, fourth-stage caterpillars the second winter.
Flight: One brood from late June-early August.
Caterpillar hosts: Dwarf willows including Salix arctica and S. reticulata nivalis.
Adult food: Flower nectar.
Habitat: Moist tundra with dwarf willows.
Range: Holarctic. Alaska east through Northwest Territories to Baffin Island, south to Yukon Territories and northern British Columbia. Isolated populations in central Canadian Rockies, southwest Wyoming, and southwest Colorado.
Conservation: The Uncompahgre Fritillary (Boloria improba acrocnema) is a listed United States Endangered Species found in the San Juan Mountains of southwest Colorado.
The Uncompahgre Fritillary has The Nature Conservancy Global Rank of G1 - Critically imperiled globally because of extreme rarity (5 or fewer occurrences, or very few remaining individuals), or because of some factor of its biology making it especially vulnerable to extinction. (Critically endangered throughout its range).
