Pearl-bordered Fritillary

The adult butterfly is orange with black spots on the upperside of its wing and has a wingspan of 38–46 mm. The underside of the wings have a row of silver-pearly markings along the edge, which give the species its name. The pearl-bordered fritillary is often confused with the small pearl-bordered fritillary, but can be distinguished by the triangle along its pearl border (the small pearl-bordered has black chevrons) as well as the presence of a single silver spot in the middle of a row of yellow spots. The female has darker markings and rounder wings than the male. The caterpillars are black with white or yellow spines along their backs. Like other species of fritillary, the males have special scent glands on their wings so that they can be recognised by females of their own species and therefore find a suitable partner.

Description in Seitz. A. euphrosyne L. (= niobe Mull.) (67h). Very similar to the preceding species, especially selene, but brighter red and the black markings thinner in typical specimens. Easily recognized by the hindwing beneath, which is bright brick-red at the base, not brown as in selene, the median band bearing only one silver-spot (across the apex of the cell) and the incomplete silvery band in the distal area being replaced by some yellow smears without any silvery gloss. The silvery marginal spots of the hindwing beneath are but very rarely absent.

The pearl-bordered fritillary is widespread throughout Europe, ranging from Scandinavia to northern Spain and from Ireland eastwards across the Palearctic to Russia and to the north of Kazakhstan. In England and Wales (plus another 10 countries) it has declined rapidly in number and is a highly threatened species.

The Pearl-bordered fritillary (Boloria Euphrosyne) is a key indicator species for well-maintained open woodlands. It is one of the first butterflies to appear in spring, making it an early sign of a healthy habitat. The butterfly’s caterpillars rely on common dog violet (Viola riviniana) and other violet species for food, thriving in recently cleared or sunlit areas. These specific habitat needs make the species particularly sensitive to environmental changes. Adult fritillaries are strong fliers, preferring warm, sheltered grasslands, woodland clearings, and meadows with plenty of nectar sources. Their dependence on carefully managed landscapes highlights the importance of conservation efforts to maintain their populations.

After mating, the female will lay her eggs on dead bracken (Pteridium aquilinum), or leaf litter near to violet plants – common dog–violet (Viola riviniana), heath dog–violet (Viola canina) or marsh violet (Viola palustris). Sometimes eggs are laid on the leaves of the food plant itself. They are laid singly, not in one large group such as the marsh fritillary. The habitat mosaics they prefer are typically one–third grass and two–thirds bracken. Eggs can be found on the food plant from mid–May to the end of June. They are a pale yellow and can hatch after 10–14 days.