Flesh fly larvae (maggots) feed on corpses and carrion, and sometimes on the wounds of mammals, hence their common name. They are also found on excrement and decaying organic matter. Adults feed on sugary liquids like nectar, sap, and fruit juice. But sometimes they just sit in the sun casting tiny shadows.
The one I photographed, above, was grooming itself on a yellow sign. It reminded me of this haiku from the Japanese poet, Kobayashi Issa (1763-1828):
Don’t strike the fly! He wrings his hands!He wrings his feet!