You may joke about the in-laws, but rodents are the real unwanted guests this time of year. Mice can squeeze through an opening the size of a dime, so stuff Xcluder, a steel-wool-type material that won't rust, into any openings (about $10; buyxcluder.com
). Then set a better mouse trap; put out six snap traps in each room where mice have been spotted and position them perpendicular to the wall, with the bait closest to the wall. Bait the traps with a tiny bit of peanut butter or bacon, but don't set them—yet. Wait a couple of days to trick the rodents into thinking the traps are a safe source of food.