News | Conservation

‘Freezing’ the decline of an iconic British butterfly

We are collaborating with Anglia Ruskin University (ARU) and Jimmy’s Farm and Wildlife Park to investigate whether a rare butterfly, the British Swallowtail, could be reared from frozen eggs in an effort to safeguard the future of the species.

Oct 03 2025

2 min read

The British Swallowtail butterfly (Papilio machaon britannicus) is found exclusively in East Anglia, predominantly in the Norfolk Broads, but its survival is threatened by habitat loss, climate change and genetic erosion due to its limited geographical range.

Since the 1970s, 80% of the UK’s butterflies have declined in their abundance or distribution. The British Swallowtail, a subspecies of the Old World Swallowtail, is classified as vulnerable on the GB Red List, with its population having declined by 57% in the last 20 years.

Together with our research partners at Anglia Ruskin University (ARU) and Jimmy’s Farm and Wildlife Park, we are exploring whether cryopreservation could help in their conservation.

Jimmy’s Farm and Wildlife Park houses a thriving captive population of a genetically similar but far more abundant species than the British Swallowtail, Papilio machaon gorganus. The eggs of these more abundant butterflies will serve as the model for our new research.

The aim of this project is to develop cryopreservation techniques to safely freeze fertilised swallowtail eggs which are laid during the breeding season. We will then attempt to rear butterflies from the frozen eggs, comparing their development and reproductive success with control groups of butterflies from non-frozen eggs. If our method proves effective, we hope that the eggs of the British Swallowtail can then be stored to support long-term conservation strategies, such as breeding programmes and reintroduction efforts.

Our research partner, Dr Alvin Helden of Anglia Ruskin University, said:

“Although this has been an excellent summer for our native butterflies, the long-term picture for the British Swallowtail is one of decline.

Our project will combine fieldwork and lab research to see if we can establish a reliable method for preserving the British Swallowtail’s genetic material by using its closely related, but less endangered, European cousin. Cryopreservation is a promising tool for supporting conservation efforts, but we believe this is the first time it has been attempted with butterflies.

We will be investigating whether the caterpillars are as healthy and whether the butterflies are as productive as those that come from eggs that haven’t been frozen. If successful, this research has the potential to help safeguard the future of the British Swallowtail and significantly contribute to butterfly conservation in general.”

Jimmy Doherty, Founder of Jimmy’s Farm & Wildlife Park, Visiting Professor at ARU, and Ambassador for Nature’s SAFE, said:

“Conservation is at the heart of everything we do at Jimmy’s Farm & Wildlife Park, from managing breeding programmes to supporting pioneering scientific research.

Our commitment to the science of entomology, and especially butterfly conservation, means this project is a natural fit for us. Partnering with ARU and Nature’s SAFE allows us to apply our expertise to work that could make a real difference in protecting the British Swallowtail for generations to come.”

This project holds significant importance for the development of cryopreservation techniques – not only for the British Swallowtail, but across pollinators and invertebrates as a whole.

Building capability in this area provides the opportunity to create impact for conservation, food production and biodiversity preservation – the critical triad for human and planetary health. Nature’s SAFE is delighted to be working closely with ARU Writtle and our conservation partners at Jimmy’s Farm & Wildlife Park.

Don’t miss

Related posts

Sumatran laughing thrush

Total Population: 2,500 - 10,000 in the wild

Brandt’s vole

Total Population: Unknown

Black-naped fruit dove

Total Population: Unknown

Red-footed tortoise

Total Population: Unknown

Patagonian Sea Lion

Total Population: 222,500 to 265,000 in the wild

Black tree monitor

Total Population: Unknown

White naped mangabey

Total Population: Around 1,000 in the wild

African penguin

Total Population: Less than 40,000 in the wild

Smew

Total Population: Around 80,000 in the wild

Azara’s agouti

Total Population: Unknown

Fea’s tree frog

Total Population: Unknown

how to help

For many species, it’s now or never.

Donate Now

or why not Fundraise For Us?

Nile Lechwe

Total Population: 30,000 - 40,000 in the wild

Asian short-clawed otter

Total Population: Unknown

Orange-headed thrush

Total Population: Unknown

Hyacinth macaw

Total Population: Around 6,500 in the wild

Inca Tern

Total Population: Around 150,000 in the wild

Guianan Squirrel Monkey

Total Population: Around 150,000 in the wild

Macaroni Penguin

Total Population: Around 12 million

Hamerkop

Total Population: Unknown

South American fur seal

Total Population: Around 200,000 in the wild