Mice take refuge where it is warm, dry and safe from predators. To a mouse, clothes dryer vents are an ideal home or a convenient way to gain entry to a house. Because indoor mice can be destructive, not to mention unhygienic, you probably don't want them nesting inside. Keeping mice out of dryer vents primarily involves blocking their entry without creating a fire hazard. A few other techniques can deter mice from your home altogether.
Examine the clothes dryer's vent flap. Ensure it closes securely and is not wedged open.
Prune or remove vegetation around the dryer vent flap and the rest of your house. Vegetation provides mice and other small rodents with cover, from which they may enter the vent or other gaps leading indoors.
Install a metal vent screen or rodent-proof vent according to its manufacturer's instructions. Do not install a plastic vent screen. Remove lint and fluff from the screen at least once each week. Lint is flammable and, when combined with heat from the dryer, constitutes a fire hazard.
Seal cracks around the vent with steel wool, and cover the steel wool with caulk. Mice cannot chew through steel wool.
Place a dryer sheet in the clothes dryer with each load of laundry. Mice are often repelled by dryer sheets' scent.
Position cotton balls soaked with peppermint oil throughout your laundry room and anywhere else you suspect the presence of mice. Put the soaked cotton balls behind the dryer, underneath the sink, in closets and along walls. Mice like dark places, but mint is repulsive to them. Refresh the cotton balls with peppermint oil every few weeks.
Employ live or snap mousetraps if you have a serious mouse infestation. Check snap traps at least once each day and live traps every hour. Dispose of dead mice in tightly knotted plastic bags in the trash. Release live mice as far from your house as possible, preferably one or more miles away.