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Mayfly Entomology

Tuesday, 26 June 2012  |  Admin

There are two speciaes of mayfly of importance to the UK fisherman, Ephemera Danica and Ephemera Vulgata. Ephemera  Lineata is rare.

The lifecycle of the Mayfly consists of 4 stages:

  1. The eggs which are dropped from the abdomen of the fertilised female as she dips it below the surface of the water. These drop to the bottom where the become attached to rocks, weeds and stones.
  2. Nymphs which spend their time living and developing in small, open-ended tunnels which they burrow into the riverbed. The nymphs have 3 long tails and an long body.
  3. After two years they go to the surface to moult. They are most vulnerable at this stage as they swim freely.
  4. The sub-imago or dun emerges, capable of flying immediately. They fly to a rock or tree for the final moult where the true mayfly emerges.


  • Nymph: males grow to 35mm
  • Adult: up to 30mm 
  • Abundant in Uk but localised in Northern Britain and Scotland
  •  May to June
  • Nymph: cream coloured body, dark markings  with 3 long tails
  • Imago: creamy body, heavy veined sparkling and transparent wings on front, smaller rear wings with 3 small tails
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