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For twenty years I have been seeing these flies regularly appear for a few days at my workplace (a small college) and then disappear again. They are most common in the bathroom, but sometimes are in the hallway too. I suspect they have a completely-indoors life cycle in this location.

Only when I looked in my lens today did I realize they are Moth flies. Any hope of narrowing the ID further?

Photographed today, West Virginia USA. Length, 4.6 mm, from front of eyes to the rear of a wing.