Saving the small things that run the planetThe Scarce Yellow Sally (Isogenus nubecula), also known as the Rare Medium Stonefly, is a Critically Endangered native stonefly which is currently only known along parts of the River Dee as it flows through Wrexham County, Wales. (View this page in Welsh)
It’s one of five species of Perlodidae, a stonefly family known from the UK, and is typically found in and around large stony lowland rivers.
Stoneflies have a key role in the life of rivers. Like all invertebrates, they are essential in the food web of their habitat for wildlife such as fish and birds. The Scarce Yellow Sally is no exception, its larvae providing food for the likes of Salmon, Sewin, Grayling and other fish native to the Dee. As adults on the wing, they are a food source to nesting birds, like Sand Martins, and newly hatched songbird chicks.
The Scarce Yellow Sally is also very sensitive to pollution, which means that they can provide invaluable information about the health of rivers. Sadly, pollution is the likely driver behind the species decline.
The Scarce Yellow Sally was thought to be extinct in Britain until a small population was found on the River Dee in Wales in 2017. We are keen to understand whether the Scarce Yellow Sally is found in other rivers, especially in and around Wales where it is currently recorded. Due to its mostly hidden lifecycle, recording stoneflies can be difficult. They spend much of their early life underwater, undergoing moults as a larva. However, as adults they leave the water and tend to frequent sunny surfaces and vegetation – that’s where you come in!
From April to June, we are asking the public to help us locate, photograph and report any sightings of stoneflies along rivers in Wales. If you live outside of this area but think you may have found a Scarce Yellow Sally, please record your sighting via the form below as well.
If you have any questions, please contact Scarce Yellow Sally Conservation Officer, Sarah Hawkes, at Sarah.Hawkes@buglife.org.uk.
The Scarce Yellow Sally Project is a Buglife partnership project with Natur am Byth! (Nature for All!). The project aims to better understand the current status of the Scarce Yellow Sally Stonefly (Isogenus nubecula) in the Welsh River Dee and engage members of the public on the importance of this stonefly.
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