Image description: an image of a caddisfly, which look similar to moths and have hairy wings, against a white background. Image by Natural Resources Wales.

A species of caddisfly, thought to have been extinct in Britain since 2016, has been found during a species survey at Cors Goch, Anglesey.

How the species was discovered

Natur am Byth (NaB), Wales‘ flagship species recovery programme, conducted the survey in partnership with RSPB and North Wales Wildlife Trust to record the caddisfly species living on the wetland habitat.

Surveyors deployed light traps on the fens during July and August, specifically looking for one of the NaB target species, Limnephilus tauricus. They were delighted to discover that the light traps had caught a species of caddisfly that is even rarer, Limnephilus pati.

There are about 200 species of caddisflies in the UK.

What does this discovery signify?

Caddisfly experts confirmed the identification, making Cors Goch one of only 3 places in Britain where this species has been found since it was presumed extinct over nine years ago. The other sites being Market Weston Fen in Suffolk and Eochar, in South Uist, Scotland.

Cors Goch is also home to two of NaB’s target species, The Clubbed General Soldier Fly, Stratiomys chamaeleon, and Dwarf Stonewort, Nitella tenuissima.

What are the chances for this caddisfly’s survival?

All three of these species rely on clean, calcium-rich waters to survive, indicating this area has clean water and a rich habitat.

The adults of this species fly from spring to early August whereas their larvae are aquatic, living amongst the roots of dense vegetation of their wetland habitats.

The habitats where they are found are often some of the most diverse in Britain. However, they are at risk from drying out and the impacts of agricultural intensification according to Natural Resources Wales.

NaB, with funding from the National Lottery Heritage Fund, works across Wales to improve habitats and minimise threats to 67 target species. You can find out more about the work being done by the programme and its partners here.