just tossing in my vote for traps--poison leaves 'em to die in the wall.... NOT GOOD!
I just found two mice face down in my electrical panel, up against the 200-amp service lugs---only dumb luck (If it weren't for dumb luck, I'd have none at all) kept my house from burning down. I guess the electrician punched out an extra hole in the panel box that he forgot to plug. I recommend you check out your panelbox for such holes! Electrical fires aside, it sucks cleaning bile from in between all the breakers!