Skip to main content

Riverflies

The Riverfly Partnership interest focuses on three key groups of riverflies: the up-wing flies or mayflies (Ephemeroptera), caddisflies or sedges (Trichoptera) and stoneflies (Plecoptera) in whatever habitats they occur (rivers and still waters).

They live most of their lives as larvae on the bed of rivers and still waters, emerging as short-lived adult flies mostly in spring and summer, often en masse.  Spectacular hatches can trigger fish feeding frenzies.  Fly fishermen study and imitate the adults in their artificial lures.

Riverflies, along with other freshwater invertebrates, are at the heart of the freshwater ecosystem and are a vital link in the aquatic food chain. Riverfly populations are affected by many factors, predominately water quality, habitat diversity, water level and flow rate.  Their common characteristics of limited mobility, relatively long life cycle, presence throughout the year and specific tolerances to changes in environmental conditions make them powerful biological indicators to monitor water quality, and are commonly referred to as ‘the canary of our rivers.’  

See Anglers' Riverfly Monitoring Initiative for further information on how angling (and other interested) groups are playing an instrumental role in protecting the health of their local rivers by monitoring their riverfly populations.

There are a total of 278 species of mayflies, caddisflies and stoneflies, of which eight species have Biodiversity Action Plan status and therefore are recognised as of priority for conservation by the government.

Riverfly articles

Articles by Peter Barnard, Scientific Director of the Royal Entomological Society and former Research Entomologist specialising in Trichoptera, on the History of fishing flies and the Swarming of riverflies published in Salmo Trutta (2005 pp.58-59 & 2006 pp.69-72 respectively) are available here by kind permission of The Wild Trout Trust.

Riverfly swarming by Peter Barnard –PDF-File, 982.7 MB

Brief history of fishing flies by Peter Barnard –PDF-File, 2.0 MB

Grannom hatch © John Levell

Grannom hatch © John Levell

Questions on riverflies

If you have specific questions concerning riverflies contact Craig Macadam from the Riverfly Recording Schemes via email info@ephemeroptera.org.uk