Pearl-bordered Fritillary - Boloria euphrosyne

Phylum: Arthropoda - Class: Insecta - Order: Lepidoptera - Family: Nymphalidae

The Pearl-bordered Fritillary has a wingspan of 38 to 47mm, and the females (example above) are on average rather larger than the males.

The common name refers to a pattern of pearly-white spots on the border of the underside (ventral side) of the wings.

Similar species

Only slightly smaller, the Small Pearl-bordered Fritillary Boloria selene differs in being much redder and having two fewer large pearl spots when viewed from the (ventral) undersides of its wings. A further aid to separating these two species is the fact that the line of white rectangles on the underwings of the Small Pearl-bordered Fritillary has much more white on it than is the case with the Pearl-bordered Fritillary.

Distribution

Once widespread and fairly common throughout Britain and Ireland, this butterfly has declined seriously in recent decades and is now common in only a few areas including central Scotland, parts of Cumbria, Devon and Cornwall and some woodlands in the south and south east of England. In Ireland Pearl-bordered Fritillaries are mainly concentrated in the limestone pavements areas of the Burren in County Clare and parts of Galway. Colonies can contain more than a thousand butterflies, but in most parts of Britain the number in a colony is rarely more than a few dozen individuals.

Elsewhere, this butterfly is known to occur in much of mainland Europe from Northern Spain up to Scandinavia and across into some parts of temperate Asia.

Lifecycle

Adult Pearl-bordered Fritillaries feed on Bugle Ajuga reptans, Ragged Robin Silene flos-cuculi, brambles and thistles. The adults mate and the females lay eggs in mid to late spring, always on or very near to violets (Viola spp.), which are the larval food plants. On woodland edges and other dryish sites with plenty of bracken, Dog Violets Viola riviniana are often selected. The caterpillars or pupae feed during summer and autumn. After hibernating, the pupae wake and continuing to feed in early spring before pupating for two or three weeks under dead bracken and then ecloding (emerging from the crysalis) as winged adults, often as early as April. This is the first of the fritillary butterflies to appear in Britain.

Acknowledgements

This page includes pictures kindly contributed Betty and Tony Rackham.

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