Two of the UKs rarest species the Duke of Burgundy and Lulworth skipper had their worst years on record in 2009, according to the annual survey by Butterfly Conservation.

Other endangered butterflies, such as the wood white and pearlbordered fritillary, have also hit new lows, the charity warns.

Butterflies are unable to fly if the rain is too heavy, and were badly hit by last years wet July and August, which followed two abysmally wet summers in 2007 and 2008.

The findings, which come from a study of butterflies at more than 1,000 sites, show that the Duke of Burgundy had its worst year in more than 30 years. The orange, brown and white butterfly used to be a common sight in woodland clearings.