From Popular Mechanics:
"As the temperature outside drops, we cozy up inside our nice, warm houses. Unfortunately, so do insects and rodents. Whether the invaders are as small as an ant or as big as a family of skunks, your best defense against pests is sealing off their entry points into your fortress."
Stop Pests From Invading Your Home This Autumn - How to Keep Mice Out of Your House - Popular Mechanics
Also: Think cat.