The Large Tortoiseshell has been classed as extinct in UK for more than 30 years, categorised as “regionally extinct” on the Butterfly Conservation’s Great Britain Butterfly red list.
However, after an increase in sightings, charity Butterfly Conservation has said if they were to update the list, the species is likely not to feature.
The butterfly species is recognised for its distinctive wings (Image: Hagen de Merak/Wikimedia Commons)
Photographs have captured the winged insect across Sussex, as well as in Kent, Hampshire, Dorset, Cornwall and the Isle of Wight.
Professor Richard Fox said: “This is great news about a beautiful and charismatic butterfly: if the individuals that are being seen can survive and reproduce then there’s no downside to the Large Tortoiseshell coming back, and we can look at what we might be able to do to help it.”
The butterfly was last recorded as a resident breeding species in the UK in the 1980s.
‘Extinct’ butterfly spotted in Sussex amid increase in sightings (Image: Algirdas/Wikimedia Commons)
There has been reported sightings since, but no evident of a stable breeding population.
Ecologists believe the species may be flying from the Netherlands, which have seen a significant growth in the Large Tortoiseshell population in recent years.
The Butterfly Conservation said it now has reason to assume the species is established in several parts of Britain.
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.”
The Large Tortoiseshell is recognisable from its distinctive orange, black and blue wings. It is closely related to the Small Tortoiseshell but has different markings.
Adults primarily lay their eggs on elm trees, with the population crash having been linked to the spread of Dutch elm disease across Europe in the 20th century.