I thought, until reviewing this picture, that what we had were mainly fungus gnats. This isn't a fungus gnat, though: it's some kind of smallish, fungus-eating fly.
I know you're thinking, but, Mr_S, aren't fungus gnats smallish, fungus-eating flies? Well, yeah, actually. But it's different. This is some other, more housefly-looking species. I know it sounds like a pretty trivial distinction, but it matters. Kinda. To me, at least. This actually looks to me more like a very young housefly, and possibly it is, though I'd be a little surprised.
Whatever the organism is, I think the picture is pretty clearly of the conqueror-stands-upon-his-conquest ilk. It'd be perfect if I could just photoshop in a tiny little Spanish flag or something.