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Hello All,
I hope you can help me identify this fly.
Pictures were taken July 1st, near Chicago, USA. The fly is nectaring on milkweed flowers (Asclepius spp.). I call him the femur fly, for obvious reasons... Thanks in advance!
Bruce Marlin

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Hello Bruce,

I think this is a species of Tropidia, maybe Tropidia quadrata but there are seven other species in North America. There are not many genera with such an apical flange on the hind femur. The (imported) European Merodon equestris has it, but mimic bumblebees.
Resembling Tropidia are some Cynorhinella, but these have a face that projects anteroventrally and the face itself is less swollen and has a very distinct median knob.

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Thanks for that ID, Paul. Any idea if this is a male or female?

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Hoi Bruce,
Happy newyear!!:D
I can tell you that this is a male.
In a lot of species of Syrphidae this is very easy to see, because in males the eyes touch over a certain distance on the upper side of the head, whereas in females there is a space in between the eyes!
But caution should be taken, this is NOT the case in all genera of syrphids. In that case it is better to look at the tip of the abdomen. Males always have a knob-like structure (as in your Sarcophaga sp.!), and in females this end of the abdomen is more flat without much to see! So, this is a male because of the touching eyes and the knob that you can see very well on your second picture!
And yes, Syrphids are one of the most beautiful families of flies! :D:D

Greetings,

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Hi Gerrard,
Happy New Year to you, and everyone!

You guys are a wealth of information, and an invaluable help to a rank amateur such as myself. Geeze, I have to learn stuff when I come here! (No, really, I find myself hitting the books and the dictionaries just to learn the terminology so I sort-of-half know what you're talking about.) I never knew about the eye distance being a gender indicator, for instance. Argh.

Good thing ignorance can be cured, eh?
Thanks for all the help.
-Bruce