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Can anyone help to ID this large fat horsefly. Dasyrhamphis atra or something similar? Many of them were busy nectar feeding, no females were biting thankfully..


c 13mm 4th June 2010 on Umbel flowers, by mountain stream , 500m in Corsica

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Profile view

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Yes, definitely Dasyrhamphis, male above and female below. There are 2 species with strongly hooked antennae - D ater and D anthracinus. The dusted subcallus (area just above the antenna) suggests anthracinus. Typically, the wings should also have a central clear area compared to ater which shows well in the field, though I think there is a lot of variation in this character. I collected a series of both sexes in Sardinia last month which I believe are all anthracinus

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Hi SD, Many thanks for the good and detailed feedback. Seems like D. Anthracinus is most likely. None of my images show an obviously clear central area in the wings, but these island populations may not have that, or variability explains the lack, Over to you to judge dusted the subcallus needs to be to confirm the ID, and here are a couple more shots showing the front of the head clearly in case they help.

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head profile close up:

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nice photos - the shot of the male conversely shows quite a polished area above the antennae cf. ater but this may be a product of direct camera flash? -the appearance can vary under strong direct lighting. Notice the clearer centre to the wings though which also seems obvious in the field when viewed oblquely.

Let me add that I'm a rank amateur, and we should let someone like Theo Zeegers have the final say!

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No flash used, just strong direct sunlight.... Thanks for the photo compliment and for helping me get close to a definitive ID and maybe one of the experts can chime in with the final word!

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I found I had one more clear image of this Tabanid. Seems it is most likely D anthracinus, but some characters point to D. ater . If anyone can be sure of an ID, I'd be grateful, but realise that is likely to be hard from photos alone.

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I agree with male anthracinus. Excellent work !


Theo

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Many thanks Theo for confirming the ID and for your kind comment. One of these flies came to a sad end soon after I photographed it alive, courtesy of a hungry crab spider, Misumenia vatia I think. Look away now if seeing a dipteran coming to such a grisly end offends!

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That why you always need to collect it !

Nature is so cruel....


Theo

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Yes, but if I'd collected the tabanids, the spider might have gone hungry and killed several rare tachinids instead... !

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in that case, the only option is to kill all spiders.....



Th.

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I thought a true dipterist might say that! As more of a generalist/photographer, i must admit to liking spiders too. Very photogenic.... but admittedly deadly and bad news for many insects.

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Hi
Spider Thomisus onustus

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I'm no spider expert, but thought T. onustus has a more angular abdomen with distinct points at the opposite sides of the abdomen. Misumenia vatia which I identified it as has a much more rounded abdomen as in my shot. Both vary hugely in colour.