How do mice get into the house?

Mice are very persistent creatures. They appear larger than they really are because of their fur. They can squeeze their bodies through extremely small openings. If they can't squeeze through they will chew their way in. Mice have narrow skulls and flexible bodies that allow them to squeeze through tiny holes and under doors. In order to prevent them from coming into your house, you can stuff some materiel under the door to bar their way.