Dorset 'butterfly banks' hope to increase numbers of Britain's smallest butterfly
The Small Blue Butterfly has been in decline
Two Butterfly Banks are to be created just outside Cranborne to encourage the small blue butterfly, the country’s smallest native species.
The banks, at Black Bush Down, will be about 30m long, 3-4metres wide and up to two metres tall, made from chalk subsoil which will be scraped from areas to the south of each bank.
Dorset Council has approved a planning application from Dr Sophie Lake of Wareham-based Footprint Ecology on behalf of the Cranborne Estate.
She says the banks will be seeded with suitable plants, including Kidney Vetch to encourage the butterflies by providing a suitable habitat in an otherwise mainly unsuitable agricultural landscape.
The small blue is known to live in the area, feeding exclusively on Kidney Vetch, but their numbers declined in line with reductions in the plant’s natural habitat.
Natural England has welcomed the creation of the two banks with support from Cranborne and Edmonsham parish council and Wimborne St Giles parish council.
The nearest population of small blue butterflies has been identified within 1,500metres in the Martin Down area with dispersal from there known to take place, especially during hot years. The application says there are no plans to move the butterflies but by offering a food source it is believed they will be attracted to the new sites.
Dorset-based Butterfly Conservation say the species is the country’s smallest resident butterfly with a wing-span of no more than 30mm, is usually confined to small patches of sheltered grassland where its sole food, Kidney Vetch, is found.
Said the conservation group: “The butterfly tends to live in small colonies and is declining in most areas. Found throughout Britain and Ireland but rare and localised.”
The eggs are usually laid from June to early July.