Why they come in during the fall
In Quebec, mice look for shelter as soon as the nights turn cold, from September to November. A heated house with food within reach gives them everything they need to get through the winter. An adult mouse can squeeze through an opening of about six millimetres, roughly the width of a pencil. The weak spots are almost always the same: pipe and cable entries, dryer vents, foundation joints, the bottom of garage doors and damaged soffits.