Brian Gaff (Sofa) wrote:
You need an entomologist and find out what they are and what they have
hatched out from. Probably a dead rat?
Brian


My guess would be a dead mouse. That's sufficient.

A dead mouse will feed a cloud of flies for
quite a while, until the carcass thoroughly dries out.

You can have a dead mouse in a wall or ceiling, and
the flies can then find a gap somewhere, so that after
lunch, they can come visit.

For confirmation, sometimes you'll catch a whiff of the
decaying mouse.

Treating the area where the cloud lives, is more efficient
than treating the area with the five flies in it.

Paul