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Flower Fly - Toxomerus marginatus - female

Flower Fly - Toxomerus marginatus - Female
Springfield, Virginia, USA
June 5, 2004
Flowerfly on a rose leaf. I originally thought it was a Toxomerus flower fly, but Beatriz Moisset made a good point (see below) and now I'm not sure. Is anyone sure what genus this belongs to?

Toxomerus marginatus
Now we know for sure. This is a female Toxomerus marginatus. according to Dr Thompson the key cited above,, is obsolete.

Toxomerus marginatus
Thanks to you and Dr. Thompson for clearing up the confusion! Much appreciated.

Is this really Toxomerus?
This fly cannot be Toxomerus. The female of the genus Toxomerus has a black band on the posterior femur that is absent in this one. See:

My attempt at identifying was based primarily upon a flower fly which was identified as a female Toxomerus marginatus by a Prof. Edward M. Barrows of Georgetown University. It can be seen here:

But since I'm definitely not an expert, I could easily be mistaken (and have been many times) in my guesses. As such, I'm moving it back to the ID request page.

Things look a lot more complicated the more you look into them. If the experts can't agree, what can we, simple aficionados do?
The guide page for Toxomerus have two very distinct types of flies, photos #3285, 5634 and 3927 fit the description for Toxomerus given in the key to Oklahoma Syrphidae, as well as the pictures in Cedar Creek guide. On the other hand, the others, including yours look like the photos for Toxomerus in the Georgetown site, in Cirrus imaging and in the USDA SEL site.
I have many photos of both of them, males and females, and have been wondering about them for a long time. The Oklahoma guide seemed to solve the mystery, and it seemed that the other sp. would be Mesograpta, which is very similar to Toxomerus, except for the characteristics of the legs of both sexes. I also see a different pattern in the abdomen of each of the two types. But, which is which?
I intend to e-mail Dr Christian Thompson of the U. of Mass. He identified some flies for me before, and is an expert on Syrphidae. May be, then we'll have a clear answer. In the meantime, keep your fly in the Flower flies or Syrphidae page, don't take it out altogether, at least we know the family (and subfamily) for sure.

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