The house mouse is the most common and economically important commensal (i.e., living in close association with humans) rodent. The house mouse is gray and it weighs on half to one ounce. The body is three to four inches long and the tail three to four inches long. The muzzle is pointed, the ears are large, the eyes and body are small. Typically, the house mouse is slightly smaller than deer mice. Adult droppings are 1/8- to ¼-inch long and rod-shaped with pointed ends.
The female house mouse reaches sexual maturity in 35 days and averages eight litters per year, each of which averages six young. Thus, with 30-35 weaned mice per year, populations build up rapidly. They typically produce their largest litters in the spring, depending on climatic conditions and begin to breed at five to six weeks of age. The life span is one year.
House mice are found throughout the United States. They are good climbers, jump 12 inches high, and can jump down from eight feet. House mice easily squeeze through holes and gaps wider than ¼-inch. They are very social in their behavior, very inquisitive about things in their environment, and readily explore anything new.
House mice prefer to nest in dark secluded areas where there is little chance of disturbance, and in areas where nesting materials, such as paper, cardboard, attic insulation, cotton, etc., are readily available. Their foraging territories are small usually no more than 20 feet; however, if abundant food is nearby they nest within four to five feet. They nibble on food, preferring items such as seeds and cereals. They feed at dusk and just before dawn.
The major health risks associated with house mice are salmonella contamination and leptospirosis.