Order Ephemeroptera – Mayflies


51 UK species, 21 genera, 10 families. These are primitive insects with hindwings smaller than the forewings. They rest with their wings closed. The nymps are aquatic, spending up to two years living underwater. Mature adults do not feed, they are short-lived, and are weak fliers, that can be seen in mating swarms, often over water.


Yellow Mayfly Potamanthus luteus

Yellow Mayfly Potamanthus luteus

Family Potamanthidae

A fairly large species of mayfly with a yellowish body and a brown-reddish stripe running along its back. Each section of the abdomen is marked with small black dots. It has three long whip-like tails and large hindwings. The eyes are yellowish-green.

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Pond Olive Cloeon dipterum

Pond Olive Cloeon dipterum

Family Baetidae (Olives)

A medium-sized mayfly with 2 tails and no hindwings.

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Baetis sp male

Baetis sp

Family Baetidae (Olives)

These are small to medium sized mayflies with two tails and small hindwings, which may be absent in some species. They are commonly referred to as the ‘olives’.

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Blue-winged Olive Serratella ignita

Blue-winged Olive Serratella ignita

Family Ephemerellidae (Blue-winged Olives)

A small to medium sized mayfly with 3 tails and large hindwings. The female has dark green eyes and the body is a greenish olive, where as the male has red eyes and the body varies between orange-brown and olive brown.

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Many thanks to Craig Macadam for his expert assistance in identifying and reconfirming species.


Useful reading: A Pictorial Guide to British Ephemeroptera by Craig Macadam and Cyril Bennet.