Britain has a butterfly back.
The large tortoiseshell — a striking, orange-winged butterfly with dark bordered markings — was once a common sight across England and Wales. Then, gradually, it disappeared. By the 1980s, the species had ceased to breed in Britain entirely. Decades passed. It was considered locally extinct.
In March 2026, Butterfly Conservation officially declared the large tortoiseshell a resident breeding species of Britain once more. For the first time in nearly 40 years, the species has a home here again.
How It Was Lost
The large tortoiseshell's decline is one of the sadder chapters in British natural history. Its caterpillars feed primarily on elm leaves — and when Dutch elm disease swept through Britain in the 1970s and 1980s, killing millions of elm trees, the butterfly's food source was devastated.
The adults can feed on other trees and flowers, but without elms to raise their young on, populations collapsed. By the mid-1980s, breeding had stopped. Only occasional lone migrants, blown across the English Channel from continental Europe, kept the species on British species lists at all.
The Return Begins
Something shifted around 2020. Lepidopterists — butterfly scientists — began finding caterpillars. Not migrants blown off course, but wild caterpillars feeding on trees in Dorset. Then in Kent. Then Sussex. Then Hampshire and Cornwall and the Isle of Wight.
Year after year, the evidence mounted. The large tortoiseshell wasn't just visiting — it was staying, and it was breeding.
In March 2026, Butterfly Conservation made it official: the species is now a resident again.
Why It's Back
Experts point to several factors working in the butterfly's favour:
- Warmer temperatures — climate change has made southern England more hospitable for species that were previously at the northern edge of their range
- Growing continental populations — large tortoiseshells are thriving in the Netherlands and France, increasing the number crossing the Channel
- Elm regeneration — young elms have been regrowing across the south of England as suckers from old root systems, gradually restoring a food source
"We're genuinely excited," said Richard Fox, Head of Science for Butterfly Conservation. "The large tortoiseshell is establishing itself again, and we want the public to help us monitor how it spreads."
What You Can Do
If you're in southern England — particularly Kent, Sussex, Hampshire, Dorset, Cornwall, or the Isle of Wight — and you spot a large, orange-brown butterfly with distinctive dark borders, report it to Butterfly Conservation. Every sighting helps scientists track the species' recovery and understand where it's establishing itself.
This is nature doing what nature does when given a chance: finding its way back.
Britain has a butterfly back. Forty years is a long time to wait, but it came home.
Sources: The Guardian (March 9, 2026) · Butterfly Conservation · GB News · Darwin Tree of Life Project · inYourArea.co.uk · Evrimagaci.org
