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Photo#400600
Syrphid Fly - Sphiximorpha willistoni - female

Syrphid Fly - Sphiximorpha willistoni - Female
Salem, Essex County, Massachusetts, USA
May 25, 2010
Reminds me of Polistes, but I couldn't find a match.

Images of this individual: tag all
Syrphid Fly - Sphiximorpha willistoni - female Syrphid Fly - Sphiximorpha willistoni - female

Moved
Moved from Sphiximorpha.

Syrphid
In photos, I can often see the halteres more easily than I can see that there are only two wings. Wasps and bees have little velcrolike hooks that hold the forewings and hindwings together, so you often can't see that detail well. But halteres are a dead giveaway--if you can see them.

The syrphid guess was based on the spurious vein. It's much clearer in Sam's image that Harsi referenced. Here's a bugguide page:

And here's a page from my site.

By the way, those bicolored wings look suspiciously like mimics of this group of wasps, which fold their forewings longitudinally:


The whole issue of mimicry is fascinating and complex.

 
OK
Stephen, thanks for the pointers. I can see the halteres and the spurious vein in my photos.

Wow, this fly's wasp mimicry sure had me fooled ;-)

 
Mimicry
The weird thing is that there are mimics--even just within syrphids--that range from very convincing (like yours) to just a couple of half-hearted stripes.

Popular science books and magazines, many textbooks, and radio and TV shows tend to concentrate on species that appear (to humans) to be really good mimics (wasp-mimic orchids are favorites). But there are many mimics that are not remotely convincing (to humans), but appear to do just fine anyway.

And we haven't even touched on ant-mimic spiders, some of which mimic the three body segments of ants in two different ways, depending on species. Some even hold their front legs up next to their heads, resembling antennae! It's hard to believe that any organism that might prey on spiders notices body segmentation or number of legs, but there you are. Ants are sour. (I know from direct experience.) And some sting. So I guess predators like birds are more observant than we might think.

Moved
Moved from ID Request.

Sphiximorpha willistonii?
Hi, Peter. Jeff and Stephen are correct that this is a fly. And, although I'm not an expert, I feel confident that Stephen is also correct that this is a syrphid. Your fly looks like a pretty perfect match for this one:


It is always possible, however, that there are other similar-looking species that I am unaware of, so feel free to wait on moving this until we here from one of the fly experts. :-)

Oh, and I believe this one would be a female, as the eyes do not touch at the top of the head. (Compare to Sam's photo of a male in the thumbnail that I referenced.)

A fly actually...
This is actually a fly, order Diptera. Note the two wings. A very beautiful fly at that, and the future of its genes depends on potential predators thinking it is something that can sting. Nice photo.

Camo worked
It's evolved to remind you--well, predators at least--of a wasp. But it's a fly.
Your nice photo shows the black-stemmed, yellow-headed halteres pretty well.
With that striking pigmentation in the leading half of the wing, I can't really tell, but I think I see a spurious vein there, which would indicate Syrphidae. I'll await expert opinion with bated breath.

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