Conservationists have confirmed that Large Tortoiseshell is no longer extinct in Britain, with the species now breeding here once again.
Although the species is officially classed as ‘regionally extinct’ in Great Britain on Butterfly Conservation’s GB Butterfly Red List, last updated in 2022, experts at the charity have said that this status will change when the next Red List assessment is made in a few years’ time.
The news follows a recent cluster of early spring records across southern England, with butterflies emerging from hibernation in counties including Kent, Sussex, Hampshire, Dorset, Cornwall and the Isle of Wight. These sightings have led conservationists to recognise the species once again as a resident rather than a migrant or vagrant.
Large Tortoiseshell was widely believed to have disappeared from Britain during the mid-20th century, with the species considered extinct as a breeding butterfly for several decades. Its decline was often linked to the widespread loss of elm trees caused by Dutch elm disease, although the precise reasons for its disappearance have never been fully understood.
Large Tortoiseshell has been declared no longer extinct in Britain by Butterfly Conservation (Bob Eade).
Britain’s 60th resident butterfly species
Recent evidence, however, suggests the butterfly has begun to re-establish itself. Since 2020, caterpillars have been discovered feeding on trees in the wild – clear proof that the species is breeding again in Britain.
Professor Richard Fox, head of science at Butterfly Conservation, said in The Guardian the development was encouraging. He commented: “The signs are really positive, which is lovely. It is resident and therefore it is another species to add to Britain’s total.”
Unlike the familiar Small Tortoiseshell, whose caterpillars feed on nettles, Large Tortoiseshell is associated with trees. Its larvae feed on species including elm, willow, aspen and poplar, and the adults typically inhabit woodland and wooded landscapes.
Large Tortoiseshell becomes the country’s 60th resident butterfly species.
Large Tortoiseshell back in Britain
Researchers believe climate change and growing populations on the European continent may be helping the butterfly recolonise southern Britain. Increasing numbers have migrated across the North Sea and the Channel in recent years, particularly from the Netherlands and France.
Although the species is not yet firmly established nationwide, conservationists say the recent breeding records and spring sightings offer hope that Large Tortoiseshell may once again become a regular part of Britain’s butterfly fauna.
Professor Fox added: “When a new species colonises, there is a period of uncertainty: many species that colonise take off and become common but some remain highly localised and can even then be lost; at the moment, for Large Tortoiseshell, we’re in that wait-and-see phase.”