Mayflies (Ephemeroptera)

I initially used the AIDGAP guide "A Pictorial Guide to British Ephemerata" by Craig Macadam and Cyril Bennett for mayfly identifications, but have found this a little frustrating at times. It's light on detail when it comes to the trickier species and some things could be much more easily explained with a few more diagrams. For a "pictorial" guide there aren't all that many pictures - for species where males and females, imagos and sub-imagos all look very different from one another there is typically only one illustrated.

I then purchased the older Naturalist's Handbook "Mayflies" by Janet Harker and John Rodford. For a couple of quid it was worth a punt and it does have some information that's missing from Macadam & Bennett that helped to clear up at least one thing I was struggling to understand using that reference alone.

Frustrated with still not being able to reach a firm conclusion with some species I eventually purchased the much heavier - and much more expensive - European tome, "The Mayflies of Europe" by Ernst Bauernfeind and Tomáš Soldán. This is much more detailed and very comprehensive, but difficult to use. The keys only go up to a point, typically genus, and it doesn't always spell out the differences between species within that genus. It does contain detailed descriptions of each species from which differences can be deduced, but it's hard going. Helpfully it has diagrams or photos of relevant genitalia etc. for many species, but not for all.

Finally I purchased - for not much money - a second hand copy of the oldest - and in many ways the best - guide to British mayflies, the Freshwater Biological Asscoiation key, "A Key to the Adults of British Ephemeroptera" by J M Elliott and U H Humpesch. I've no idea why I didn't get this earlier - maybe I didn't know about it, maybe I knew it was missing some species, or maybe I just assumed that the later guide would be better? Anyway, my first impressions are that it is very clear with some really good diagrams that would have been really helpful to have included in the more recent works. I'm sure some things are out of date but as an aid to clear up species that are tricky using Macadam & Bennett, this would have been a much better investment than the European guide (though I'm happy to have that as well!).

Lots more species to cover here in due course...

Caenis macrura

Caenis robusta