"Derek Turner" wrote in message
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On Thu, 01 Jul 2010 12:12:01 +0100, Mentalguy2k8 wrote:

They're black and smaller than house flies.

Probably thrips a.k.a thunderflies, from your description of their
behaviour.


I looked those up, and it's not them. The ones I have are like "normal"
flies that you get in the house and on dog poo (the big blue/green ones that
buzz), except they are quite a bit smaller and don't land on anything, don't
seem interested in people or food. They are hanging around in seemingly
pointless groups like gnats do. If they landed on something I might be able
to work out what they're feeding on, but all they do is hover and jerk
around within the space of about a square yard. I can't see where they're
coming from or where they're going. All I know is that for every dozen I
kill, they're calling for backup and are back up to full strength within
minutes. But if I don't kill them, I still have the same number, it's not
like they're continually arriving, they just seem to reach a certain number
and maintain it.

Have tried spraying citronella on the door frames, curtains etc., but it
doesn't seem to bother them.