Flies are insects that belong to the order Diptera.
It is a large order containing an estimated 1,000,000 species including horseflies, craneflies, hoverflies and others.
However, of these only about 150,000 species have been described.
It is one of the major insect orders with ecological and human importance.
Larger flies such as tsetse fly and screwworm cause significant economic harm to cattle.
Blowfly larvae, known as gentles, and other dipteran larvae, are known more generally as maggots.
Flies are used as fishing bait and as food for carnivorous animals. In medical debridement, they are used to clean wounds. (source)
So can hamsters eat flies at all?
They aren’t good for hamsters to eat as they maybe carrying parasites that could harm a hamster.
If they are bred in captivity, they are fine for them to eat but anything caught in the wild shouldn’t be fed to them.