I have had to use these lockable rat poison boxes myself. As Jenny says, with an infestation spreading to your house one has to do what must be done.
These boxes can be put in raised places, shed roofs, lofts, or maybe garden tables well out of hedgehogs accessibility. I have not placed any at ground level myself and I abhor the thought of placing them under sheds/decking (rat hidey holes) because of any risk to other wildlife.
A rat only needs a 20 mm hole (less than 1 inch) due to their flexible structure so can clearly access every gap and crack. I sometimes have a box on a shelf in a shed when seems necessary – rats have chewed through my brand new shed door to access chicken feed.
Like you Jenny it does go against my conscience, I don’t even kill flies, but their are times we must do what we can. A neighbour of mine had rats hanging from trees to eat birdfood, then in his house. Be careful, responsible and sensible.
