The large tortoiseshell butterfly, once considered extinct in Britain, has been confirmed as a resident species again following a series of early spring sightings across southern England. Butterfly Conservation has added the insect to the UK's native butterfly list, bringing the total to 60 species.
Sightings have been reported in Kent, Sussex, Hampshire, Dorset, Cornwall and the Isle of Wight, with individuals emerging from hibernation in woodlands. The charity says this marks the first time in its 58-year history that the large tortoiseshell has been classified as a resident rather than a migratory species.
Richard Fox, head of science at Butterfly Conservation, described the signs as "really positive" but cautioned that the butterfly is not yet fully established. "It's not well-established enough yet to say it's definitely back for good," he said. "We're still in that zone of uncertainty, but there are exciting signs."
Unlike the common small tortoiseshell, the large tortoiseshell is a tree-dwelling species whose caterpillars feed on elm, willow, aspen and poplar. Its decline was once linked to Dutch elm disease, but experts now believe Britain may have always been at the northern limit of its range, and its return may be aided by global heating.
The butterfly first reappeared in significant numbers on the south coast in 2006-07, but many sightings were attributed to unauthorised releases. Since 2020, wild caterpillars have been found feeding on trees in Dorset and elsewhere, confirming breeding. The charity urges the public to log sightings on the iRecord app to help track its spread.
