Why do flies circle the centre of a room even when there's no light on?

Question

they tend to fly in circles under the lampshade on the ceiling even when it isn't on.

Answer 1

Best Answer - Chosen by Voters

I don't know why, but it may be something to do with the heat of the cooling bulb or even some sort of sonar, the flies have where they have more mobility as a swarm in more open space? Thats the best i could do,

Answer 2

Seems like a good way to spend the day until the light comes on.

Answer 3

It has to do with stagnant air flow. Put a fan on them and they'll disperse.