The descriptive text, below the map, is from the Cornish Red Data Book (2009). The map on this web page depicts the organisms distribution and shows the records made pre-2000 and those made since.
Range & Status
Extremely local in Britain, but often abundant where found. Recorded in Windermere and Coniston Water (English Lake District), Mochram Loch (Dumfries & Galloway), Lower and Middle Lakes (Killarney). Larvae which key out as this species using the modern texts have recently been recorded from a river in Devon. Confirmation by adult capture or rearing is important to ensure it is this species and not a new species to Britain.
The two 1961 records for VC2 could have been mis-identified as this species, using
some identification works. However, the recent discovery of larvae (probably this species) in running water in the south-west suggests that these records may be correct and for conservation purposes are best treated as such at the present time.
Habitat & Ecology
Confined to localised populations inhabiting the littoral regions of lakes and tarns in the UK and Ireland. Recorded in rapid mountain streams on the continent.
This species is sensitive to pollution.
The host watercourses should be given special recognition to ensure protection against changes to river morphology, water quality and bankside management.
I.J. Bennallick, S. Board, C.N. French, P.A. Gainey, C. Neil, R. Parslow, A. Spalding and P.E. Tompsett. eds. 2009. Red Data Book for Cornwall and the Isles of Scilly. 2nd Edition.Croceago Press.
The Cornish Red Data Book Project was led by the Cornwall and Isles of Scilly Federation for Biological Recorders (CISFBR). The full text and species accounts (minus the maps) are available on the CISFBR website.