How to tell house flies from flesh flies?

I posted an observation of what I thought was a House Fly, i.e. Family Muscidae. But as you can see, two other people came along and IDed it as a Flesh Fly, Family Sarcophagidae.

The reason I thought it was a House Fly is because of the black-and-gray striping on the thorax; but it seems that Flesh Flies have that, too, because I have since seen several more observations with that pattern and that ID. So, what features can be used to distinguish the two families?

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3 lines in Sarcophagidae, 4 in Muscidae, plus habitus (often longer legs with thick bristles).
Official answer is lower squama in Scatophagidae is rudimentary, occupit with white hairs, frons is widened in both sexes. In Muscidae A doesn’t reach the edge of the wing (to divide it from other Muscoidea).


Musca domestica has a yellow abdomen.

They didn’t mention M. domestica? Just Muscidae. (It seems the OP might think that Muscidae=House Flies)

See if it eats your house or if it eats your flesh


According to iNat, Muscidae are House Flies and Allies. Although some of the observations on that page look like Calliphoridae (greenbottles and bluebottles) to me.

Those are muscids too, you can check their observations with ids.

Yes, House Flies and Allies. The name House flies only includes a few species at the moment, as most Muscids don’t have common names. The ones that look like Calliphorids are still Muscids.

Well, then I have to ask the obvious followup question, namely, how do I tell those two apart?

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Calliphorids have mostly white heads, whereas the similar Muscids, like Neomyia, have shiny heads.

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On a general level, in insects it is quite normal that similar looking species belong into different families, and it is often not easy to name ‘obvious’ features that are a common to a certain family (like the color or stripes on the thorax for example).
Seeing tiny spines on the legs, counting bristles on the thorax or looking at minute hairs at hidden places can be the most reliable, but of course hard to find features, especially when you are not an expert in that group.
In this ID key for blow flies, you can read how to separate the different families of the calyptrates (house flies, flesh flies, tachinids etc.) on pages 10-11 and on page 12 there is a nice overview of lookalike species, belonging to different families:

Also, I can highly recommend the work of @edanko, he put a lot of effort to describe all diptera families:
And for your specific request here, the calyptrates:

I can vouch for him as well :wink:

Oh, you changed your profile pic.

I was actually wondering why you didn’t take the opportunity here to promote your brother’s work :wink:


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