Deer mice are structural pests in rural, summer/vacation, outbuilding, and shed-type structures, as well as suburban homes located in or near wooded areas. They are of medical concern because they are the primary carriers of hantavirus which causes hantavirus pulmonary syndrome (HPS). The deer mouse is found throughout North America.
Adults with head and body length are about 2 3/4-4”, tail length is about 2-5” long. They are bicoloured, pale greyish buff to deep reddish brown above and white below. The tail is always sharply bicoloured and is longer than half the length of the head and body combined.
Deer mice are nocturnal. Their runways are poorly defined and they often use the runways of other small mammals. They are excellent climbers and can utilize the upper areas of buildings, etc. Outside, they nest in old fence posts, tree hollows/cavities, log piles, abandoned bird/squirrel nests and animal burrows, beneath decks, or dig small burrows. Inside, they nest in storage boxes, stuffed furniture, cabinet drawers, wall voids, on sill plates, in structural corners, and tight places in basements and attics.
Deer mice feed on insects, seeds, nuts, berries, small fruits, a subterranean fungus, and other small animals such as centipedes, snails, slugs, dead mice, and young birds. Food is stored for the winter in hollow logs and other protected places. Deer mice are rarely a problem in urban or residential areas unless homes border on wooded areas, such as parks.