Small Pearl-bordered Fritillary

Small Pearl-bordered Fritillary Boloria selene (Denis & Schiffermüller 1775)

Family: Nymphalidae, subgroup Argynninae (the Fritillaries)


Photo above top left by N Dove

Photo above top right by D O'Brien

Photo above left by D O'Brien (also header photo)

Phtoto above right by Dave Williamson

The Small Pearl-bordered Fritillary (SPBF) is a beautiful delicate looking butterfly with bright orange upperwings, patterned with black and white edges.

It can be confused with the much rarer Pearl-bordered Fritillary (PBF), although the PBF is so restricted in its Yorkshire distribution that it is unlikely to be seen. As a guide the SPBF prefers damper sites than the usually solitary PBF. The SPBF is usually smaller, but sizes do overlap. For diagnostic separation look at the closed-wing view. The SPBF has thicker black lines dividing cells, giving a richer, brighter, stained-glass window effect whereas the PBF has lighter colours, suffused with ochre and pale mustard, and divided by finer lines.


The SPBF uses woodland glades, mires, damp grassland and rush pasture, grassland with bracken or scrub and woodland edges with open glades, where violets Viola spp (particularly Common Dog Violet V. riviniana and Marsh Violet V. palustris) grow. In Yorkshire, marsh violet appears to support the butterfly on a majority of sites. In the west, Austwick Moss, Wharfe Woods (both VC64), Rise Hill (VC65) and other sites possess areas where the plant is abundant, but there are also patches of common dog violet occurring sparsely on adjacent drier land. In County Durham, egg-laying has been observed-on common dog violet adjacent to mires containing marsh violet and is considered to be an important site component (EIIis 2000).

However, the Yorkshire situation is unclear. Some North York Moors (VC62) sites are exclusively of common dog violet, which occurs in low densities on dry grassy bank edges, or amongst light bracken litter (e.g. the southern half of the Newton Dale population). Marsh violet sites are typically found on moorland mires, rush pasture or marshy grassland with a wet peaty surface and impeded drainage. The violets grow in discrete areas on the margins of the wettest mire habitats, usually within rush pasture and often on the sides of tussocks, which may be an important structural component in the ecology of both larvae and violets. On the North York Moors, this habitat is also found within coniferous forest, usually adjacent to a beck. In VC62 it is probable that in the past the butterfly was largely dependent on coppicing, but now exploits whatever suitable habitat remains. By contrast, in the west it seems to have been using the same mire habitats for two millennia (Whitaker 2002, 2003).

The most commonly used nectar-source is Marsh Thistle Cirsium palustre, although Ragged Robin Lychnis flos-cuculi and Cuckoo Flower Cardamine pratensis are occasionally visited and wild Raspberry Rubus idaeus is used at Raygate Slack. Although any small flower proud of the foliage can be picked out by the butterfly, it seems incapable of distinguishing those growing amongst leaves. To this end it has developed a technique, which involves crawling through the leaves and stalks, with proboscis unfurled and trailing beneath, in contact with the foliage, until a flower-head is encountered and the butterfly stops to feed (Sean Clough pers obs.). At Deepdale Meadow, the most abundant flower on one visit was Common Cat's-ear Hypochaeris radicata, which was used on 13 out of 16 visits by two nectaring females (Sean Clough pers obs.).


The SPBF is a scarce resident due to the loss of many central Yorkshire sites during the 20th century as well as threats to remaining sites. It survives in localised colonies in the western Yorkshire Dales and North York Moors, with Dales butterflies typically emerging around 10 days later than those on the Moors, largely due to altitude but also (more anecdotally) greater cloud cover and lower mean temperatures during earlier stages. Some North York Moors forest sites appear to have become shaded out.

Worldwide it is found from Spain to Norway and across Europe, Asia and North America, but is absent from Ireland, most of Italy and Greece.

Life Cycle

There is usually only one brood (univoltine). Sticky eggs are placed singly, or dropped into vegetation near the foodplant and hatch within about a fortnight.

Small larvae feed until their fourth instar (late September) when they enter hibernation. Emmett and Heath (1989), suggest the larvae overwinter beneath leaves or in ground detritus, but this probably only applies to woodland sites. Hibernation sites in moorland mire populations are not known, but may be within Juncus or Purple Moor Grass Molinia caerulea tussocks. Feeding recommences in April and a full-grown fifth instar larva is about 20mm long, blackish, with yellow spines, a brownish dorsal line and a pinkish lateral stripe. Two longer, horn-like spines push forward over the head. Larvae are secretive, hiding in the shadier parts of the vegetation, and only emerging for feeding forays.

The pupal stage begins late May in Yorkshire and lasts about three weeks. Brown pupae, dotted with metallic silver spots, are suspended from silk pads, low down on a plant stem or in the detritus.

Adults fly in June and July. The males patrol almost constantly in suitable weather and mating takes place as soon as virgin females are discovered, with no courtship involved (Sean Clough pers obs.). Mated females divide their time between basking low in vegetation, nectaring, and searching for violets. When suitable foodplants found, the female crawls as far as possible into nearby vegetation before curving her abdomen and dropping an egg into the growth below. Although Emmet & Heath (1989) suggested egg-laying takes place only in the afternoon, this has been observed in both morning (09.30- 10.30hrs) and afternoon (14.45hrs) in VC62 (Sean Clough pers obs.).


  • Section 41 species of principal importance under the NERC Act in England

  • Listed on Section 7 of the Environment (Wales) Act 2016

  • Scottish Biodiversity List

  • UK BAP status: Priority Species

  • Butterfly Conservation priority: High

  • European Status: Not threatened


The SPBF has over 30 named aberrations including variations in ground colour ranging from white through cream and buff to darker melanic forms. One Dales colony consistently produces a high proportion of individuals with a darker dusting than normal.

Scotland has its own more brightly marked form: insularium.

With thanks to The Butterflies of Yorkshire edited by Howard M Frost

Catherine Jones 10/05/21