thank you for this advise!
it has had me thinking, in the 'scrap wood for burning' pile, there is just such a construction! the rat holes are against the wall of the runs, inside, so if i securly peg this box over the hole with the trap iside hopefully i will start catching.
i did buy a trap a while ago, but not worked out a way to safely use it yet. what is the best bait to put on it?
that breeding info makes me realise i best get on with this!!