Butterfly Declared Extinct in Britain Makes Remarkable Comeback Across Southern England

In a remarkable conservation story, the large tortoiseshell butterfly has been declared a resident species in Britain once more — decades after it was believed to have gone extinct in the country. Sightings have been confirmed across woodlands spanning Kent, Sussex, Hampshire, Dorset, Cornwall, and the Isle of Wight, marking the first time in the charity Butterfly Conservation's 58-year history that the species has been classified as resident rather than a rare migrant.

The large tortoiseshell's disappearance from Britain was long attributed to Dutch elm disease, which devastated elm tree populations across the country from the 1960s onward. Elm trees were a primary food source for the butterfly's caterpillars, and their loss was thought to have eliminated the species from British shores. The last confirmed resident colonies disappeared in the early 1960s.

“Sightings have been confirmed across woodlands spanning Kent, Sussex, Hampshire, Dorset, Cornwall, and the Isle of Wight, marking the first time in the charity Butterfly Conservation's 58-year history that the species has been classified as resident rather than a rare migrant.”

The butterfly's return has been gradual. Occasional sightings in recent years were initially dismissed as migrants blown across the English Channel from continental Europe. But the pattern of sightings in 2026 — multiple individuals observed across a wide geographic range during early spring — convinced experts that breeding populations have re-established themselves in southern England.

With the large tortoiseshell's return, Britain's native butterfly count has risen to 60 species — a cause for celebration among conservationists who have watched with concern as many butterfly populations have declined in recent decades due to habitat loss, pesticide use, and climate change. The comeback provides a rare piece of positive news in the often-grim landscape of insect conservation.

Conservationists remain cautiously optimistic about the species' long-term prospects. While the spring sightings are encouraging, experts note that the population is not yet well-established enough to declare it permanently returned. Adult butterflies from this year's offspring will take flight during midsummer, providing another opportunity to assess population viability.

The large tortoiseshell's return is believed to be connected to changing climate patterns that have made southern England more hospitable to the species, as well as the recovery of some elm populations that provide food for caterpillars. It demonstrates nature's remarkable capacity for recovery when conditions improve — even for species once thought to be permanently lost.