British Insects: the Genera of Ephemeroptera


L. Watson and M. J. Dallwitz

Baetis Leach

Imago. The compound eyes distinctly two-lobed (in males), or rounded (in females); upper lobe in the males, turbanate.

Fore-wings with R5 detached basally from R4. The marginal fore-wing veinlets paired. Hind-wings present. The hind-wings of the female imagines no more than one fifth the length of the fore-wings. The hind-wing costa smoothly curved, or with a conspicuous projection. Hind tarsi with 4 moveable segments, or with 2–3 moveable segments (?).

The abdomen with two tails.

Nymph. The outer tails hairy on the inner side only. Gills mostly at the sides of the abdomen; not fringed with filaments on both sides; never comprising a plate bearing a tuft of filaments.

Classification. Superfamily Baetoidea. Family Baetidae.

British representation. 9 species; B. atrebatinus (Dark Olive Dun and Spinner), B. buceratus, B. digitatus, B. fuscatus (Pale Watery Dun and male Spinner, Golden Spinner female), B. muticus (Iron Blue Dun, Iron Blue or Jenny Spinner male, and Little Claret female Spinner), B. niger, B. rhodani (Large Dark Olive Dun and male Spinner, Large Red female Spinner), B. scambus Small Dark Olive Dun and male Spinner, (Small Red female Spinner), and B. vernus (Medium Olive Dun and male Spinner, Red Spinner female).

To view illustrations with legends giving names in current use, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa, as well as source references and other relevant material.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. British insects: the genera of Ephemeroptera. Version: 29th December 2011.’.