A BUTTERFLY which was put on the at-risk register due to Dutch Elm Disease has been discovered at a wood near Swindon.

The white-letter hairstreak, also known as Satyrium w-album, has been discovered at Clouts Wood, Wroughton.

A visitor to the site, which is run by the Wiltshire Wildlife Trust, discovered a small green lava which later turned out to be of the species, this weekend.

It is the first time the species has been recorded at the wood.

Wiltshire Wildlife Trust's reserves field officer, Ellie Jones, said the trees on offer at Clouts Wood provided a perfect spot for species like the white-letter hairstreak.

"Clouts Wood is fortunate to support a number of healthy mature wych elm trees, which provide fantastic habitat for the white-letter hairstreak," she said.

"Our long association with the wood, made possible by the enduring support of The Hills Group and other friends, has ensured that these trees have been retained.

"Our ongoing management will now focus on protecting and enhancing habitat for this species at the reserve and adjacent Kings Farm Wood."

The small green larva was spotted by the visitor, who was delighted at his discovery of this elusive species, Ellie said.

White-letter hairstreak caterpillars feed exclusively on the flower buds and leaves of elm trees, and the butterfly suffered heavy declines as a result of Dutch Elm Disease in the 1970s and 1980s.

Unfortunately, this decline has continued, with a fall in the UK population of 55 per cent in recent decades, the trust said.

The white-letter hairstreak is in flight between mid-June and mid-August.

Anyone keeping their eyes peeled for a glimpse of the species should look for its small, dark body flying erratically around the tops of large elms.

The butterfly is so-named because of the W-shape etched in white on the underside of the hindwing.