BUTTERFLIES are thriving on land at Porton Down, the Government's chemical research centre, despite the floods last summer.

The number and variety of rare species such as the heath butterfly, dingy skippers, marsh fritillaries and grizzled skippers have increased alongside common farmland butterflies on the Ministry of Defence-owned farmland, according to the Wiltshire Wildlife Trust.

Populations have shot up following a reseeding programme of grasses and flowers by the Defence Science and Technology Laboratory (DSTL).

A three-year study revealed that in 2005 before reseeding began on the margins of the arable land, 211 butterflies from 14 different species were recorded.

This rose to 6,980 butterflies from 26 different species during the 2006 hot summer.

In 2007, 1,415 butterflies of 24 species were recorded - showing a significant increase despite poor conditions during the wet summer months, the charity said.

Stuart Corbett, of DSTL, said: "Excitingly, more BAP (Biodiversity Action Plan) rare species appeared - dingy skippers and marsh fritillaries in May and grizzled skippers in June.

"The presence of the marsh fritillaries on an arable margin was totally unexpected and led to the discovery of a new population at Porton Down."