Mating Thick-Headed Flies from Ontario

Subject: Chalcid wasp?
Location: Peterborough ON
May 26, 2016 9:02 pm
I found these small (1mm+) wasp-like insects mating in my backyard on the weekend – May 24. It was sunny and warm: around 26C.
Signature: Rob Tonus

Mating Tiny Flies
Mating Thick-Headed Flies

Dear Rob,
Our initial impression that the faces on your mating insects looked more like Flies than Chalcid Wasps proved correct when we zoomed in on your very high resolution image, which revealed the presence of halteres which are defined on Entmologists’ Glossary as “modified wings. In the Diptera (true flies) it is the hind wings that have become halteres. …  Halteres are shaped like ‘drum sticks’ with a slender shaft connected to the thorax at one end and ending in a thicker structure at the other. Halteres are highly sophisticated balance organs and they oscillate during flight.”  So these are mating Flies.  We are going to post your submission as unidentified while we continue to research the identity of your mating pair of Flies.  We will also contact Eric Eaton to get his input.

Eric Eaton Responds
Sure:  Thick-headed flies, family Conopidae, maybe Myopa for genus?

Ed. Note:  This image on BugGuide looks very close, but it is listed as 12mm, not 1mm.  According to BugGuide:  “Myopa species are parasitic on Honey Bees Apis mellifera, Andrena and Mustache Bees Anthophora.”

Thanks so much for the quick feedback, Daniel.  I appreciate you investigating these mystery insects for me.

Thanks again for this additional information.
The flies were larger than 1 mm, but much smaller than 12 mm – perhaps 5 or 6 mm at most . . . that’s only an estimate, though, since I saw them mating, and they could have had their abdomens twisted, which made them look shorter.
Are these presumptions on genus the closest we’ll get to identifying them?  Is it difficult to determine species without having them in hand?

Perhaps a Dipterist may be able to do a conclusive species ID, but alas, we have not the necessary skills.

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