Adults are about one inch tall, and 3-4 inches long, not including the tail. They live in extended families, or colonies, with each colony establishing a territory by marking boundaries with urine and droppings. When infesting schools, droppings are frequently the first indication that there are mice in the building. The chances of actually sighting a mouse are fairly slim, unless they have lived in the building long enough so as to lose some of their fear. This is due to the fact that mice are primarily active at night, and although they have poor eyesight, their bulging eyes allow them to detect movement in any direction.
Mice also have a keen sense of hearing.
They are very sensitive to small, and have no problem detecting food, even if it is packaged, unless the food is in an airtight container. The young mice will be able to breed for the first time between 5 and 8 weeks after birth. Nests are made in dark secluded places out of cloth, chewed paper, or any other soft material available. There are few places mice cannot go. These hairs let a mouse know quickly if a tiny opening is large enough for its body.