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Hello,

Well, while taking pictures of any living being, as usual, I came across this one. In the first time, I thought this was a E. balteatus, but found it too dark indeed. I further photographed, thinking I would be able to sort the matter out.

As a matter of fact, I think this is a dark form of E. balteatus.

Any objections ?

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Yes, this is a dark specimen of Episyrphus balteatus.
Mostly it happens when something disturbes their pupal stage, like a too high or low temperature!
greetings,

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Gerard,

Thanks for the explanation.

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Hello,

I posted this picture in the Gallery and Paul labelled it "intersex". Could you explain, Paul?

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When you examine the head, you will see that the eyes are separate (so not a male) but they are closer together than in 'regular' females. In several species similar specimens can be found and these always have a darker abdomen or the pattern is even completely absent (e.g., 'Scaeva unicolor'. Internal examination has revealed that these specimens, though mostly resembling females, have no ovarioles and neither do they have male genitalia. I am not aware of any examination of chromosomes, but these specimens appear to be neither male not female and have often been labeled as 'intersex'.

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Paul,

Thanks for the precious information.

That would mean that le cold weather (the cold/hot envrionment G. Pennards mentionned, in our case, is the little glaciation we had over the last two weeks) coud also provoke a misdevelpment of the sexual apparel ?

Or are those aspects totally distinct?