MOUSE

House mouse (Mus musculus) any of many small, scampering rodents, particularly the house mouse (Mus musculus; see photograph), family Muridae (order Rodentia). The term mouse, like the term rat, has no scientific definition; it is used simply to designate any of numerous ratlike, but small, rodents. Many species of the large family Cricetidae (grasshopper mice, harvest mice) are called mice, as are members of the families Muridae (Old World mice), Heteromyidae (pocket mice), and Zapodidae (jumping mice and birch mice). The marsupial mouse is not a rodent but a mouselike relative of the kangaroos. Mice are common and are indigenous to almost every land area. They eat various foods, including grain, roots, fruit, grass, insects, and in some instances human foodstuffs. Many species seem to prefer dwelling in man-made structures and can become serious pests by destroying food, gnawing all types of materials, and, possibly, harbouring such disease-producing organisms as murine typhus and plague. Mice living in the wild may be so numerous as to become serious, although usually temporary, agricultural pests. Except in abnormal circumstances, however, mice are beneficial to man because they form the bulk of the diet of most furbearers and of predators that otherwise would take more valuable animals, including livestock. Serious household infestations of mice may require the services of trained exterminators, but minor infestations can be handled adequately and most safely by trapping. The house mouse, the mouse most often encountered in buildings, has been distributed by man from Eurasia to all inhabited areas of the world. It usually seeks shelter and food in human dwellings. A brown or gray rodent, it grows up to 20 centimetres (8 inches) long, including a 10-cm tail. It consumes almost anything edible, even sampling soap, paste, and glue. It matures quickly, being ready to mate two to three months after birth. Litters consist of as many as 12 young; gestation takes about three weeks. In warm areas or heated buildings, breeding occurs throughout the year. The common white laboratory mouse is a domesticated form of the house mouse that is widely used in medical experiments and is also commonly kept as a pet. Various other strains of house mice include: piebald mice; singing mice, which emit faint twitterings; and waltzing mice, which cannot move normally because of an inherited, defective sense of balance. See also field mouse; harvest mouse; spiny mouse.