The UK's largest butterfly, the rare Swallowtail, is making a comeback following a century of decline.
The Swallowtail, which was once a common sight across the country, can now only be found in the Norfolk Broads.
The butterfly's population, which has been in decline for 100 years, is now increasing, say conservationists.
The success is being put down to fen management over the past 15 years.
This has resulted in an increase in milk parsley, a favourite food source for the Swallowtail caterpillar.
This year, butterfly watchers reported seeing the distinctive yellow and black-winged insects in greater numbers than ever before.
The turnaround in fortunes began in the late 1990s when a programme of harvesting the fen and clearing scrub which had been invading the region began.
Government funding from agri-environment schemes to landowners helped finance the work.
Andrea Kelly, head of conservation at the Broads Authority, said: "This restoration programme is a fantastic demonstration of how funding is providing magnificent wildlife results for seven million visitors who visit the Broads' magical waterland each year.
"More visitors are saying that they have easily spotted Swallowtails this year."
The Swallowtail butterfly has a wingspan of up to 80mm (3.15in).
These butterflies usually produce two to three broods from April to September.