In a remarkable twist for British conservation, a species of insect believed to have vanished from the UK nearly a decade ago has been rediscovered in the wilds of north Wales. The Limnephilus pati caddisfly, last recorded in Britain in 2016 and presumed extinct, was found alive and well at Cors Goch Nature Reserve on Anglesey. This unexpected find, confirmed on September 17, 2025, has sent ripples of excitement through the ecological community and renewed hope for some of the country’s most threatened wetland habitats.
Surveyors from Natur am Byth, Wales’ flagship species recovery programme, together with the RSPB and North Wales Wildlife Trust, made the discovery while conducting a summer survey at Cors Goch, near Llanbedrgoch. Their mission was to search for another rare caddisfly, Limnephilus tauricus, but instead they netted an even rarer prize. Using light traps set on the reserve’s fens during July and August, the team captured a moth-like insect that was later identified as Limnephilus pati, a species previously thought lost to Britain’s fauna.
The significance of this find is hard to overstate. According to BBC News, Anglesey is now one of only three places in Britain where the Limnephilus pati caddisfly has been recorded since 2016. The other sites are Market Weston Fen in Suffolk and Eochar on South Uist in Scotland’s Outer Hebrides. This tiny, brown insect—often mistaken for a moth due to its hairy wings—has become a symbol of hope for conservationists fighting to preserve the UK’s dwindling wetland habitats.
“Anglesey is the only known place in Wales where you can find this unique caddisfly,” explained Clare Sampson, Natur am Byth project manager for RSPB, in a statement to North Wales Live. “It was a delight to find it at Cors Goch along with a number of other species that indicate clean water and a rich habitat.”
Caddisflies, sometimes called “sedge flies,” are a diverse group with around 200 species found in the UK. They’re perhaps best known for their remarkable larvae, which construct protective cases from stones, sand, and leaves, wrapping them in silk. These aquatic larvae thrive in dense wetland vegetation, while the adults—a short-lived but vital food source for fish and birds—take to the air from spring until early August. Unlike moths, caddisflies have fine hairs on their wings rather than scales and are most active at night, often swarming over water.
The rediscovery of Limnephilus pati was more than a stroke of luck. The survey team’s use of light traps was part of a targeted effort to document the reserve’s insect life and monitor the health of its wetlands. As Sampson noted, “Discoveries like this prove that there are always exciting finds in nature, and they can be found right on your doorstep.” She stressed that such finds highlight “why consistent surveying is such an important element of conservation work.”
But the story of Limnephilus pati is not just one of serendipity. Its survival is intimately tied to the fate of Britain’s wetlands, some of the most diverse yet imperiled habitats in the country. The caddisfly requires exceptionally clean, calcium-rich water to survive—a resource that is becoming increasingly scarce. According to Deeside.com, these habitats face mounting threats from drying out and agricultural intensification, as well as pollution from nearby farms. The situation is so precarious that Cors Goch’s continued ability to support Limnephilus pati is seen as a testament to the reserve’s ecological health.
“Caddisflies survive by being masters of disguise; the brown adults blend into the vegetation, while the larvae live inside cases that they camouflage with stems, sand and seeds,” Sampson told The Cambrian News. “By gathering data on our most at risk species and their habitats we can focus our work where it’s needed most and ensure their survival now and into the future.”
The Cors Goch Nature Reserve is not just a haven for Limnephilus pati. The site also supports other rare and threatened species targeted by the Natur am Byth programme, including the Clubbed General Soldier Fly (Stratiomys chamaeleon) and the Dwarf Stonewort (Nitella tenuissima). Like the caddisfly, these species depend on the reserve’s clean, calcium-rich waters. Their continued presence is a strong indicator that, for now at least, Cors Goch’s wetlands remain a sanctuary in a landscape increasingly shaped by human hands.
The rediscovery has also shone a spotlight on the vital role played by ongoing conservation efforts. Natur am Byth, backed by funding from the National Lottery Heritage Fund, works across Wales to improve habitats and reduce threats for 67 target species. The programme’s partnership with organizations like RSPB and North Wales Wildlife Trust has been crucial in sustaining the kind of long-term, detailed fieldwork that makes moments like this possible.
Yet, as the experts involved are quick to point out, the discovery is as much a warning as it is a cause for celebration. The habitats that support Limnephilus pati and its fellow wetland dwellers are under constant threat. Drying wetlands, pollution, and agricultural change can quickly tip the balance, leading to the loss of species that may not be noticed until it’s too late. Consistent surveying and data gathering, as Sampson emphasized, are key to spotting changes early and directing conservation resources where they are most needed.
For those who care about Britain’s natural heritage, the return of Limnephilus pati to the scientific record is a reminder that even the rarest creatures can persist against the odds—if their habitats are protected and the right eyes are looking. “This incredible discovery shows why consistent surveying is such an important element of conservation work,” Sampson said. “By gathering data on our most at risk species and their habitats we can focus our work where it’s needed most and ensure their survival now and into the future.”
The story of Limnephilus pati is a testament to the resilience of nature and the dedication of those who work quietly, year after year, to keep watch over Britain’s wild places. As conservationists celebrate this rare find, their message is clear: the fight to preserve Britain’s wetlands—and the hidden wonders they contain—has never been more urgent, or more rewarding.
