Flies are among the fastest of all flying insects and they have the ability to land anywhere, even upside down on ceilings. The buzzing sound that flies create are the sound of its wings beating. This beating can range from 200 to 2000 beats per second depending on the species, its age and its size. Values for wing beat frequencies are different for different species of flies due to the difference in wing structure, width, length and muscular components. Age also plays a role in how fast a fly flies because of effects of aging on the flight muscles in the fly wings.
Older flies have a slower wing beat frequency.
Size also contributes because wing beat frequencies are generally higher in small flies than in big flies.