I have a small problem with flies. However, I don't know what kind they are. they're black, smaller than houseflies but larger than fruit flies.

They hover only in the centre of rooms, with a very specific behaviour: they go one direction for 20-30 cm and then suddenly jerk back toward the centre of the room. They are always in a cluster, but I don't think they are cluster flies because they don't make any noise. They don't seem to be mind being misted with water, or smoky rooms. They also don't seem to be particularly attracted to light.

They are silent, don't land on food and don't seem to be causing any problems except being distracting and in the way. But that's enough! Does anyone know what they are, or how to get rid of them?

Thanks,

Martin

I know you wrote your post a long time ago, but I thought I'd reply anyway.

Last Spring, I suddenly has a fly problem in my house. Apparently, a couple of flies got in my house and mated. Suddenly, there were flies on every window. I personally flushed 50 of them down the toilet in the course of two days.

Finally, I got some flying insect spray. I watched the flies to see where else they would land besides my windows. By studying their behavior, I found the "nest" (if there is such a thing) in a high recessed light fixture. I sprayed it well with insect spray. That solved the problem.

Nowadays, I kill any fly that comes into my house as quickly as possible. I had no idea that flies could mate and duplicate inside your home. Perhaps this is what is happening to you.

Another suggestion: check all your screens, screen doors, etc for holes. Have them patched. Don't keep doors or windows open unless they are properly screened.

Good luck.