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I had fun photographing these flies. Repeatedly, one fly would encounter another and they would fly round and around each other like in a whirlwind.

The first image shows the antennae with what looks to me like a bare arista, which made me think of Tachinidae.

The second image includes the bristly rear of the fly which looks right for Tachinidae.

That large white area near the base of the wing, is that the "well-developed post-scutellum"? I first thought maybe it was a calypter, but it appears to be below the wing.

Data: meadow not far from woods, stream, and wetland. West Virginia, USA. Date was 16 July 2006. Size about 4.75 mm.

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Here is a second photo of this fly.

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certainly looks like a tachinid but not sure which one. Do you have a side-profile of the head?

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Alas I didn't take a lateral shot. I'm posting below a view that is a little less perfectly dorsal than the other one...

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Hmm, well it's certainly a tachinid ... but can't say more than that :)

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Thanks, Chris. I liked both the interesting looks of this fly and its behavior (with them whirling around each other). Your comments will send me back into the field for other photos, including a lateral one and maybe one of the face too for good measure.

As always, thanks for your help with this one!

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Hi Stephen ... you can never have all the angles but try to get a good dorsal view so we can see wing venation and the bristles on the thorax and abdomen clearly. Then a good shot of the head face-on or to the side is always useful because facial bristles, eye hairs and the arista figure commonly in the key. A good lateral body shot can often show us any important leg bristles and even katepisternal bristles, which are sometimes important :)

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This is a male of Winthemia, probably quadripustulata


Theo Zeegers