Observe a fly up-close as it washes its “hands,” legs, and face, including its large compound eyes. This macro footage captures some classic fly behavior: Rapid leg-rubbing to clean itself. Via AskAScientist.nz, Canterbury Museum entomologist Simon Pollard writes:
When a fly lands on a piece of food, it `tastes’ the food with its feet. Special sense organs on its feet can tell the fly what type of food it has landed on, and whether it can eat it. It is very important for a fly to keep its feet clean, so it can identify what it has landed on. In the world of flies, tiny particles, like pollen grains, dust – which is mostly bits of dead skin, bits of dead insects etc, can become stuck to the fly’s body, and especially the feet, when the fly is walking around.
Flies, by rubbing their legs together can clean off these tiny particles. Imagine if your feet became covered in oranges and you had to brush them off with your hands. Flies also clean other parts of their bodies, like their eyes, by brushing over them with their legs.