Small pearl-bordered fritillary (Boloria selene)
| Kingdom | Animalia |
|---|---|
| Phylum | Arthropoda |
| Class | Insecta |
| Order | Lepidoptera |
| Family | Nymphalidae |
| Genus | Boloria (1) |
| Size | Wingspan: 3.6 - 4.2 cm (1) |
Not listed under any conservation designations.
This species is similar in appearance and size to the pearl-bordered fritillary (2), but has darker brown spots on the underwing and more pearly-silver spots. The caterpillar reaches 2.2 centimetres in length, has a pinkish-brown body with black marks and spines along the back; the pair of spines behind the head are long and horn-like (3).
Widespread throughout central and northern Europe and Asia. In Britain it has undergone a drastic decline and is now extinct in central and eastern areas, and is close to extinction in central-southern England. Strongholds remain in Scotland and Wales (2).
This species is found in four habitat types: woodland clearings, damp grassland and moorland, grassland with scrub patches or bracken, and open wood-pasture and woodland edges in Scotland (2). In all cases it requires abundant sources of the main larval foodplants, common dog-violet (Viola riviniana) or marsh violet (V. palustris), amongst damp grass and vegetation (4), and plenty of nectar-rich flowers as adult food-sources (4).
Adult small pearl-bordered fritillaries fly between late May and late July, a single brood is produced per year. Eggs are laid singly on the foodplants or on dead plant matter close to the foodplant (2). Larvae hibernate towards the end of August (3) when they are still small, and emerge the following spring to complete their development (4). Pupation occurs in May and adults emerge about ten days later (3).
The decline of the small pearl-bordered fritillary started towards the end of the nineteenth century and reached severe proportions after the 1950s. The habitats used by this species have remained relatively unchanged in Scotland and Wales, but in England agricultural changes have caused widespread losses. In England these butterflies are now only found in woodland clearings, which have decreased in abundance due to the demise of coppice management (2). This species increased in numbers during the 1950s and 60s because many woods were felled and replanted at this time. These woods have now matured and become too dense for this, and many other woodland butterfly species (2), resulting in huge declines (2).
Where the small pearl-bordered fritillary occurs in bracken-dominated habitats, grazing is essential to maintain a patchwork of grass and bracken with plenty of foodplants available. In woodland habitats it requires clearings connected by broad rides (2) to allow it to disperse to newly created clearings (4). Conservation measures carried out for the similar pearl-bordered fritillary will also benefit this species (2).
For more information on the small pearl-bordered fritillary see:
- Butterfly Conservation's Species Action Plan: Butterfly Conservation:
www.butterfly-conservation.org/ - Butterfly Conservation's Species Action Plan:
www.butterfly-conservation.org/downloads.asp?PageId=73 - Asher, J., Warren, M., Fox, R., Harding, P., Jeffcoate, G., and Jeffcoate, S. (2001) The Millennium Atlas of Butterflies in Britain and Ireland. Oxford University Press, Oxford.
Information authenticated by Butterfly Conservation:
http://www.butterfly-conservation.org/
- Coppicing: traditional form of woodland management in which trees are cut close to the base of the trunk. Re-growth occurs in the form of many thin poles. Woodlands are cut in this way on rotation, producing a mosaic of different stages of re-growth.
- Hibernation: a winter survival strategy characteristic of some mammals in which an animal's metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is 'diapause', a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
- Larvae: stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
- Larval: of the stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
- Pupation: the process of becoming a pupa, the stage of an insect's development, when huge changes occur that reorganise the larval form into the adult form. In butterflies the pupa is also called a chrysalis.
- Rides: often the footpaths and access tracks which run through and divide blocks of trees in woodland. Many rides contain a mixture of rich flora and structure, and provide different habitat conditions for a range of wildlife.
- Still, J. (1996) Collins Wild Guide: Butterflies and Moths of Britain and Europe. HarperCollins Publishers, London.
- Asher, J., Warren, M., Fox, R., Harding, P., Jeffcoate, G. and and Jeffcoate, S. (2001) The Millennium Atlas of Butterflies in Britain and Ireland. Oxford University Press, Oxford.
- Carter, D.J. and Hargreaves, B. (1986) A Field Guide to Caterpillars of Butterflies and Moths in Britain and Europe. Collins, London.
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Barnett, L.K. and Warren, M.S. (1995) Species Action Plan: small pearl-bordered fritillary, Boloria selene. Butterfly Conservation, Wareham. Available at:
http://www.butterfly-conservation.org/uploads/spbf_action_plan.pdf