Attics provide mice with dark areas where they can nest in the insulation. Signs of mice in the attic include droppings, nests built of feathery paper scraps, and gnawed wood. Sometimes they can be heard scurrying overhead at night. Mice enter attics by climbing rough surfaces, such as woodpiles, and crawling underneath roof rafters.
Mice in the attic can cause considerable damage. They chew up wiring, contaminate insulation and air with their feces, and gnaw holes in the ceiling. Mouse droppings can carry dangerous airborne diseases such as Hantavirus. Also, mice in the attic may visit other places in the house in search of food. A mouse infestation, if left alone, can grow in size and cause even more damage.
Preventing mice from entering your attic in the first place is the best method of control. Mice are great climbers, so remove woodpiles, hanging vines, or anything else that would allow mice to climb into the attic. Seal up any holes under roof rafters with cement. Mice also enter attics through holes above garage doors. If a population already exists, do-it-yourself control methods include trapping and poisoning. Wooden traps are very effective and should be placed in areas known for mouse activity. Humane mouse traps can be used by homeowners who want to catch and remove mice without killing them. An attic is the safest place to use poison, because it is inaccessible to children and pets. However, poison kills mice over a period of days, making dead mice hard to find. It is very important to clean up mouse droppings and urine puddles. This prevents fecal dust from spreading disease. Use a surgical mask, gloves, and a disposable broom and dustpan. If insulation is severely contaminated, it may be easier to replace with fresh insulation.