Rodents

Every September, as nighttime temperatures drop, house mice and deer mice begin probing New England foundations for a way in — and a gap the width of a dime is a front door. Once inside they nest in insulation, contaminate everything along their runways (a mouse dribbles urine more or less continuously), and gnaw. The gnawing is the expensive part: rodents' teeth grow constantly, and electrical wiring insulation is a favorite chew — rodents are a leading suspected cause of attic and wall fires of 'unknown electrical origin.'

Worth knowing

• A house mouse can produce up to 10 litters a year — two mice in October is a population by January.
• Deer mice (the ones with white bellies) are the local reservoir for hantavirus and the host that infects ticks with Lyme bacteria.
• Mice can climb rough vertical surfaces and jump a foot high; 'it's too high up' rarely rules out an entry point.