An exciting arrival in the garden

Ephemera danica - The Mayfly - lying spent on the pond

At the weekend I was very pleased to find a spent female of the mayfly Ephemera danica on the New Pond – this is The Mayfly.

The nearest stream is 250 m away, from where she most likely came. I am hoping that, presumably having been attracted to the gravelly substrate, she will have gone on to deposit her eggs in the pond.

The arrival of this animal is interesting for a couple of reasons.

First: The Mayfly is usually thought of as a classic lake or river creature. But its arrival at our little garden pond neatly exemplifies the rule that many animals thought of as exclusively riverine also turn up in ponds, sometimes more often than we imagine.

The three species of Ephemera found in Britain are amongst our biggest mayflies and a splendid sight during May as they emerge – mainly from from rivers, streams and lakes and sometimes bigger, usually gravelly, ponds. Two are common, The Mayfly and the Dark Mayfly, and one a rarity, Ephemera lineata –  I don’t think it yet has a formal English name but I’ll call it the Lined Mayfly.

In fact Ephemera danica is not often seen in ponds – we found it in just one river valley pond in Wales in a survey of 200 top quality ponds across the whole of Britain. The more pondy species is the Dark Mayfly (E. vulgata). As far as I know, the Lined Mayfly has not been recorded in ponds at all.

The second thing that’s interesting about the arrival of Ephemera danica in our pond is it illustrates how river animals don’t just fly up or downstream looking for new habitat: some also go sideways. It makes sense for a proportion to do this, to ensure that they don’t get stuck in one river or stream valley where conditions may become unsuitable. And if you’re going to go sideways, away from the river, you can imagine how it would also make sense (in evolutionary terms) to be able to survive not just in running water but also in ponds, either to provide a stepping-stone to a new river valley, or to allow for later recolonisation of the natal river, perhaps after some major disturbance – like a big flood or a severe drought.

We don’t know how often this happens – but if I can see it after just one year in our new pond, I don’t think it can be a terribly rare event.

Now I’m keeping my fingers crossed that there will be some babies – that would be exiting.

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4 Responses to “An exciting arrival in the garden”

  1. Joe Berry Says:

    Interesting stuff. Nice to hear about the ecology of some of these species! Thanks also for the information about pond plants in the preceding posts. Garden centres really don’t provide a good range of plants for wildlife ponds – or wildelife gardens in general – and they are so expensive.

  2. Jeremy Biggs Says:

    Hi Joe

    There’s masses to be said about plants and how to better with them.

    We’re thinking about ways of trying to improve the availability of plants – although going into ‘the wild’ remains our preferred option at present.

    But we’ll need to establish some national ground rules about that so that we don’t have any disasters. I can just see the headline: ‘The last remaining……..in……was yesterday picked by a pond enthusiast following the advice of charity Pond Conservation to ‘go wild’ when stocking their ponds.’

    And although they say all publicity is good publicity, I think that in this case it probably isn’t!

    Jeremy

    • Tristan Hatton-Ellis Says:

      This morning I was rather surprised to see a small mayfly (Baetis I think, though my mayfly ID isn’t all it should be) sitting on the roof of my car. On looking around I was surprised to see five or six more ‘dancing’ above – more than I usually get over the pond! I expect they were attracted by the reflective surface of the roof – there are reports of water beetles crashing into greenhouse rooves etc for the same reason.

      We have a stream in the valley but this is a good half mile away; the garden pond is closer but even this is probably 100m or so. Perhaps the mayflies are dispersing more than usual because it is so dry.

  3. Calum Says:

    I have just been looking for some info on mayflies and found this site. I have them flying into my kitchen from my pond. Just wanted to say that it is a koi pond but has a separate filter which I has dragon/damselfly larvae as well as mayfly larvae in it and we often see them moulting on the iris I’ve put in there, only other plants present at the time is water cress and an arum lily.

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