Silver-spotted skipper (Hesperia comma)
| Kingdom | Animalia |
|---|---|
| Phylum | Arthropoda |
| Class | Insecta |
| Order | Lepidoptera |
| Family | Hesperiidae |
| Genus | Hesperia (1) |
| Size | Wingspan: 2.5 – 3 cm (1) |
Protected in Great Britain by the Wildlife and Countryside Act 1981, with respect to sale only (2).
This butterfly is orange-brown in colour with pale spots that are more noticeable on females. The underside is pale brown with silvery spots, and males have a black band on the upperside of the forewing (1). The caterpillar reaches 2.6 centimetres in length, and has a dull olive-green body with a black collar behind the large black head (3).
The rare silver-spotted skipper is found across Europe and throughout temperate Asia. In Britain it is restricted to chalk downland in southern England following a substantial decline which resulted in its extinction in Yorkshire, the Cotswolds, the northern parts of the Chilterns and much of the North Downs (4).
Breeds on warm, south facing slopes in open chalk grassland with short turf and patches of bare soil. The presence of the larval foodplant, sheep's-fescue (Festuca ovina), is essential (4).
The flight period occurs between late July and early September. This species is single-brooded; eggs are laid singly on the leaves of sheep's-fescue growing in a short sward next to patches of bare soil. The eggs remain un-hatched through winter; larvae emerge in early spring and feed beneath small protective webs. Pupation occurs in a cocoon at ground level (4).
Habitat loss and fragmentation has been a key factor in the decline (2). Agricultural intensification has removed much habitat, but neglect and a decline in grazing results in the sward growing too high for the species. Grazing by rabbits decreased the effect of abandonment, but myxomatosis caused a crash in rabbit populations in the early 1950s. The silver-spotted skipper went into rapid decline as a result of the decrease in grazing (4). A combination of the recovery of rabbit populations and targeted conservation work resulted in a partial recovery of this butterfly in the 1980s and 1990s (4).
Targeted conservation work continues on a number of nature reserves and Sites of Special Scientific Interest (SSSIs). Agri-environment schemes such as Countryside Stewardship and Environmentally Sensitive Areas, include measures to encourage farmers to manage their land in ways that benefit this species (4). An increase in stock grazing, preferably by cattle, in important sites will decrease this skipper's dependency on rabbit grazing, which is often unpredictable (4).
Conservation of the silver-spotted skipper requires a landscape-scale approach, as the species persists in 'metapopulations', occupying discrete habitat patches connected by dispersal over quite large areas (4). A number of reintroductions to nature reserves in Kent have been attempted, as natural recolonisation was unlikely (4). The silver-spotted skipper is a priority species under the UK Biodiversity Action Plan (UK BAP) (2).
For more information on the conservation of British butterflies see:
- Butterfly Conservation:
www.butterfly-conservation.org
Information authenticated by Butterfly Conservation:
http://www.butterfly-conservation.org
- Agri-environment schemes: these schemes allow the government to compensate farmers for using methods that benefit the environment. The two main initiatives in the UK are the Countryside Stewardship Scheme and Environmentally Sensitive Areas. Since October 2000 these have formed part of the England Rural Development Programme (EDRP), administered by DEFRA, the Department of Environment Food and Rural Affairs.
- 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.
- Metapopulations: a set of local populations within some larger area, where typically migration from one local population to at least some other patches is possible.
- Myxomatosis: a contagious viral disease in rabbits.
- 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.
- Single-brooded: Also known as ‘univoltine’. Referring to an organism which has just one brood each year.
- Still, J. (1996) Collins Wild Guide: Butterflies and Moths of Britain and Europe. HarperCollins Publishers, London.
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UK BAP (March, 2002)
http://www.ukbap.org.uk - Carter, D.J. and Hargreaves, B. (1986) A Field Guide to Caterpillars of Butterflies and Moths in Britain and Europe. Collins, 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.