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No not an old house. Never had so many flies in loft before. Mice have been there for months and months now. They are coming in somewhere from the roof. Still catching some live mice in humane traps, but the poison is getting eaten as well. The loft has a bedroom built 30 years ago, and doors around the edges, mice are in the parts of loft behind doors, we keep the doors shut all the time with poison and traps behind the doors, and store things like suitcases in there (which I make sure are zipped up!). There can be nowhere else the flies are coming in from, they must squeeze through the edges of the doors and get in the main bedroom part. Just wondered how long they will keep appearing.