Butterfly ID
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Field guide · Sweden
Brush-footed butterflies · Sweden

Arctic Fritillary

Boloria polaris

One of Sweden’s most threatened butterflies, known only from two small mountain ridges north of Torneträsk. It is circumpolar in distribution in the Arctic. In the 2020 Red List, it is assessed as strongly threatened (EN).

Status in this countryThreatened in SwedenEN (Endangered)
Arctic Fritillary
Photo: Matt Muir · CC BY 4.0

Flight period

The flight period normally begins in the first week of July and lasts 2–3 weeks; in early summers it may start as early as mid-June.

Habitat

High mountain and tundra in rain-poor areas, primarily on the tops of mountains up to 1,000 metres in height.

Identifying features

Wingspan 34–43 millimetres. The underside of the hindwing is reddish-brown with a white, irregular, and black-edged band, as well as T-shaped white spots that are bordered inwards by triangular, dark brown spots. These T-shaped spots are the species’ most prominent characteristic.

Similar species

Closest to being confused with Freija Fritillary (Boloria freija) and Purplish Fritillary (Boloria chariclea); the T-shaped white edge markings distinguish the species from both.

Distribution

Sweden is known only from two smaller mountain ranges within the mountain region north of Torneträsk; otherwise, it has a circumpolar distribution throughout arctic Asia, North America, and Greenland.

Biology

The developmental stages are poorly known in Sweden; the life cycle is thought to take at least two years. Mountain avens has been proposed as a host plant.