Monday, September 17, 2012

What's the model for this mimic?






Hoverflies, without stings, are well known for mimicking the colours and patterns of stinging wasps so the standard issue markings for most hoverflies are some variation on the theme of black and yellow stripes. This species, Leucozonia glaucia, is the exception to the rule and is turned out in this attractive black and denim blue colour scheme ...... which begs the question as to whether it's mimicking something or is simply a genetic variant with no particular natural selective benefit or disadvantage. 



According to British Hoverflies by Alan Stubbs and Steven Falk the markings on this species are normally yellow but this blue variant occurs frequently.  I haven't encountered it often and this one is part of a population that lives along a woodland ride in Hamsterley Forest, Co. Durham and is often quite abundant when hogweed and angelica are in flower. This individual is a female, identifiable by the widely spaced eyes.




It seems to have been quite a good summer for some hoverflies in my part of Co. Durham. I had a quite a few of this one, which I think is a particularly attractive variant of Helophilus pendulus, in my garden where it seemed to be partial to meadow crane'sbill flowers. 




I'm not completely sure what this large hoverfly species is but I think it may well be Sericomyia  silentis..... a convincing wasp mimic. It's been quite common in Teesdale throughout August and early September and I've seem several on  devil's bit scabious, which is supposed to be particular attractive to this species.


10 comments:

  1. They are all so smartly turned out aren't they? Pretty little things.

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  2. It could almost be the world's smallest and squattest dragonfly! Funnily enough, several dragon and damselflies have blue colour morph females. And even some species that aren't blue, will turn blue when it's not warm. Like they aren't difficult enough to identify already!

    Gorgeous shots, Phil :o)

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  3. Most unusual colouring - have never seen a blue one.

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  4. These are, as always, very lovely and vivid shots. But I don't know about hoverflies, if i see something like these here, to me they are just lumped together as flies. I wonder how insects were able to mimic another, and how long the mimicking ability was evolved! amazing strategy, but i think it is not them who strategize that ability!

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  5. ... especially when they're hovering in a shaft of sunlight, toffeeapple ...

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  6. Interesting that you should mention that Graeme, because about 200 metres along the forest ride from these blue hoverflies there's a pond with plenty of hawker dragonflies ....

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  7. I wonder if it's because they are easily overlooked or because they have a very local distribution, John ...?

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  8. Hi Andrea, there's a lot of research by evolutionary biologists on mimickry in butterflies. One of the first to describe it was Henry Bates - info at http://en.wikipedia.org/wiki/Henry_Walter_Bates

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  9. Wonderful photographs.
    I've never seen one of those Levi coloured ones. I'll be out there scanning the fennel when the sun comes out.

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  10. It might be mimicking the denim clad youngsters:}

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