Picture-winged Fly waves her wings while eating

A Picture-winged Fly (family Ulidiidae) -- probably Euxesta notata (whose larvae are known as Spotted Root Maggots), or something similar -- finds a fresh patch of bird poop on the concrete wall of an inlet for the main retention pond at Arthur Storey Park, in Houston, TX, USA.

As she begins to eat, she starts waving her wings, as if to indicate her excitement at finding a delicious meal. Interestingly, members of genus Euxesta are supposed to attack plants, but maybe that's only their larvae, since I've only ever encountered the adults on poop (which is true of most Picture-winged Flies that I've encountered).