House mice—Mus musculus, as they are known on formal occasions—are wondrously adaptable with regard to environment. Mice have even been found living in a refrigerated meat locker kept permanently chilled at –10 degrees Celsius. They will eat almost anything. They are next to impossible to keep out of a house: a normal adult can squeeze through an opening just three-eighths of an inch wide, a gap so very tight that you would almost certainly bet good money that no grown mouse could possibly squeeze through it. They could. They can. They very often do.
