A previously unknown population of the dark bordered beauty moth, one of England's rarest insects, has been discovered at the National Trust's Wallington estate in Northumberland, a site where the species had not been recorded since 1952. The find gives conservationists a second known English location for the moth, whose only other population, at Strensall Common in Yorkshire, has been shrinking because of climate change and wildfire damage.
Dr Dave Wainwright, head of conservation at Butterfly Conservation, has spent his entire career searching for new colonies of the moth and described the discovery as one of the most significant moments of his working life.
How was the moth rediscovered?
Wainwright first visited Wallington in search of the species back in 2004, the year he joined Butterfly Conservation, but found nothing at the time. Returning to the estate more recently, he and colleagues spotted a moth within minutes of beginning their search.
"I was hopeful - I'm always hopeful- but I definitely didn't expect it because I've been to so many sites to look for this species over the years, so my heart and head were in two different places,"
He said the sighting ranked among the standout moments of his career and brought a deep sense of relief that conservationists were no longer relying on a single English site.
"It was one of the highlights of my career."
"Overwhelmingly it was just a feeling of relief that we weren't just fighting the fight at one site anymore."
Why is this population significant?
The dark bordered beauty was once common across northern England and Scotland, but habitat loss has left it clinging to a small number of surviving sites. Butterfly Conservation says the species is now restricted to just a handful of locations in Scotland and, until this discovery, a single site in England, favouring open, damp, scrubby or heathy grassland close to tall trees, according to Butterfly Conservation. UKmoths similarly describes it as an extremely local species found in only a couple of locations in Scotland and northern England, according to UKmoths.
The pressure on the species has been well documented at its last known English stronghold. A 2016 study found that the Strensall Common population declined by an average of 30 to 35% annually between 2007 and 2014, a drop linked to changes in the availability of its host plants, according to a scientific study published in the journal Insect Conservation and Diversity. Separately, earlier reporting described the moth as being on the brink of extinction at that site, with numbers falling by more than 90% to an estimated 50 to 100 individuals. The same scientific record also lists Newham Bog in Northumberland as a former English site where the moth is now considered extinct.
The moth's caterpillars will feed on only two plants, aspen and creeping willow, a narrow diet that Butterfly Conservation says makes the species particularly difficult to conserve.
What does this mean for conservation efforts?
Wainwright said Wallington's landscape differs markedly from Strensall Common, which had until now shaped conservationists' understanding of what constitutes suitable habitat for the species.
"The thing that's kept me going all these years is I always felt there was a chance of finding dark bordered beauty on the Northumberland/Cumbria border – now it feels like there could be other colonies out there waiting to be discovered which would be brilliant,"
According to a report from a London-based news outlet, the newly found colony emerged after Wallington's habitat was improved through nature-friendly farming, reduced grazing and peatland restoration, with the first moth reportedly spotted within about ten minutes of the search beginning, according to the Standard. Wallington ranger Emily Johnson said the estate is now regarded as a stronghold for the species, according to the Standard, suggesting conservationists see the find as more than an isolated record.
The National Trust, which manages Wallington, said it hopes to expand the amount of potential habitat available for the moth on the estate. The discovery echoes other recent conservation successes involving rare British insects, including the rediscovery of the carrion clown beetle in Northern Ireland, unseen there since 1934, and efforts such as the reintroduction of the black-veined white butterfly at Dartmoor Zoo, both of which reflect growing momentum in citizen and organised conservation work across the UK.
What happens next?
Conservation work at Wallington will now turn to expanding and actively managing habitat to support the newly identified population, according to the Standard. Wainwright and colleagues also plan to continue monitoring the estate and searching nearby sites, believing further undiscovered colonies may exist along the Northumberland and Cumbria border, the same report notes.
Key Facts
- The dark bordered beauty moth was rediscovered at Wallington, Northumberland, having last been recorded there in 1952.
- Its only other English population, at Strensall Common in Yorkshire, has declined sharply due to climate change and wildfire.
- A 2016 study recorded annual declines of 30 to 35% at Strensall Common between 2007 and 2014.
- Caterpillars feed solely on aspen and creeping willow, limiting suitable habitat.
- The National Trust plans to expand potential habitat at Wallington to support the population.
