‘Extinct’ East Anglian bug rediscovered ... in Scotland

A caddisfly species called limnephilus pati which was once found on the East Anglian fens but was thought to be extinct in...

A caddisfly species called limnephilus pati which was once found on the East Anglian fens but was thought to be extinct in the UK has turned up on a Scottish island - Credit: Robin Sutton - Credit: Archant/Robin Sutton

A bug once found in the fens of East Anglia but thought to have become extinct in the UK has turned up on a remote Scottish Island.

Limnephilus pati is a species of caddisfly presumed extinct in the UK in 2016 after no British records of sightings in more than 100 years.

But conservation body Buglife said in July last year — against all the odds — a male of the species was attracted to a light trap monitored by Robin Sutton on South Uist in the Outer Hebrides. 

Robin Sutton discovered the Limnephilus pati caddisfly at Eochar in South Uist, a remote Scottish island

Eochar in South Uist in the Outer Hebrides where the Limnephilus pati caddisfly - which was thought to be extinct - was discovered - Credit: Robin Sutton

Photos of the specimen were sent for identification and it was found to be the long-lost limnephilus pati.

It's still too early to say whether the exciting find means it could be reintroduced to sites such as Redgrave Fen on the Suffolk/Norfolk border where it was once found.

A view across part of the Redgrave and Lopham Fen nature reserve

A view across part of the Redgrave and Lopham Fens nature reserve where the 'extinct' caddisfly species was once found - Credit: Steve Aylward

Mr Sutton said: “I’ve been running a light trap on the Outer Hebrides for over four years but I couldn’t believe that the only location for a species thought to be extinct in Britain was in my back garden. It goes to show how much we still have to find out about these far-flung places.”

Buglife conservation director Craig Macadam said: “It is really exciting that this species, thought to be extinct, has been rediscovered in the British Isles.

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"We don’t know a lot about its requirements, but the discovery of this new population means that we might be a step closer to working out what has driven the declines of this species elsewhere.”

South Uist is rich in habitats for caddisflies, with numerous small lochans, clear, low nutrient streams, and extensive machair habitats. Over the years 23 species of caddisfly to Mr Sutton’s light trap but by far the most exciting find is Limnephilus pati.

Outside of the UK, there are 16 historical sites where the bug has been found across Denmark, France, Germany, Ireland, the Isle of Man and Poland.

Mr Macadam admitted that experts don’t know much yet about the species.

"It was first described as new to science in 1980 from specimens collected in Ireland. As a caddisfly it is likely that the larvae are living in small pools and ponds in the peatland that is common in South Uist. This is similar to the peaty conditions found in the Fens.

"As to why it became extinct in England, you can never tell absolutely why a species might have died out. The site of the previous records are Chippenham Fen in Cambridgeshire and Redgrave Fen in Suffolk.

"Both of these are National Nature Reserves and are billed as relict fen sites. Perhaps it’s the fact that other sites nearby have been lost and these have become isolated populations, perhaps it’s some subtle change in the habitat or water quality, or perhaps it’s due to climate change with the exact habitat of the species drying out at some point.

"Alternatively it could be a one-off event, for example a long, dry summer that coincided with when the species wasn’t in the egg stage and unable to retreat to deeper water. To be honest we’ll never know for sure.

"That leads on to the likelihood of being able to reintroduce it. Until we know more about what conditions the species likes and what habitat it needs we can’t plan any conservation work, and certainly not a reintroduction. The discovery of the specimen on Uist gives us an opportunity to start working out its requirements so that maybe one day we could be able to introduce it to other sites."