If unchecked, one pair can produce 6 to 12 young in 21 days. Sexual maturity is reached at 3 months. Therefore, assuming adequate food, water, and shelter, a single pair of rats may multiply into more than 640 rats in 1 year. House mice usually weigh less than 1 ounce and are grayish-brown in color. They are masters at gaining access to buildings and will chew, gnaw, climb, or swim to reach their destination.
House mice are primarily nocturnal.
However, unlike Norway rats and roof rats, seeing mice during daylight hours does not necessarily indicate a high population. House mice will eat just about anything, but they prefer grains and seeds. However, they eagerly consume foods high in fat, protein, or sugar. One characteristic that distinguishes them from Norway rats and roof rats is their ability to survive with little or no free water. They get the water they need from the foods they eat.