HOUSE MICE

Damage Prevention and Control Methods

Exclusions

• Seal all openings larger than .25 inches wide

Habitat Modification

• Good sanitation practices reduce sources of food, water, and shelter
• Store foodstuffs in rodent-proof structures or containers
• Control weeds and remove debris from around structures

Trapping

Identification
The house mouse is a small, slender rodent that has a slightly pointed nose; small, black, somewhat protruding eyes; large, sparsely haired ears; and a nearly hairless tail with obvious scale rings. House mice are considered among the most troublesome and economically important rodents in the United States.

Adult house mice weight about 2/5 to 4/5 ounce. They are generally grayish brown with a gray or buff belly. Native to central Asia, this species arrived in North America with settlers from Europe and from other points of origin. A very adaptable species, the house mouse often lives in close association with humans and therefore is termed one of the "commensal" rodents. House mice are much more common in residences and commercial structures than are rats.

Habitat
House mice live in and around homes, farms, commercial establishments, and in open fields and agricultural lands. The onset of cold weather each fall in temperate regions may cause mice to move into structures in search of shelter and food. House Mice are the most common mammal in cities, next to humans.

Food Habits
House mice eat many types of food but prefer seeds and grain. They are not hesitant to eat new foods and are considered "nibblers," sampling many kinds of items that may exist in their environment. Foods high in fat, protein, or sugar may be preferred even when grain and seed are present. Such items include bacon, chocolate candies, butter, and nutmeats. House mice can survive with little or no free water, although they readily drunk water when it is available.

General Biology, Reproduction, and Behavior
House mice are mainly nocturnal, although at some locations considerable daytime activity may be seen. Seeing mice during daylight hours does not necessarily mean that a high population is present. Mice have poor eyesight, relying on their hearing and their excellent senses of smell, taste, and touch. They are considered color-blind; therefore, for safety reasons, baits can be dyed distinctive colors without causing avoidance by mice.

House mice may burrow into the ground in fields or around structures when other shelter is not readily available. Nests are constructed of shredded fibrous materials such as paper, burlap, or other similar items, and generally have the appearance of a "ball" of material loosely woven together. They are usually 4 to 6 inches in diameter.

Mice may breed year-round, but when living outdoors, they breed mostly in spring and fall. A female may have 5 to 10 litters per year. Mouse populations can therefore grow rapidly under good conditions, although breeding and survival of young decline markedly when population densities become high.

House mice have physical capabilities that enable them to gain entry to structures by gnawing, climbing, jumping, or swimming. Studies indicate that during its daily activities, a mouse normally travels an area averaging 10 to 30 feet in diameter. Mice seldom travel farther than this to obtain food or water.

Mice constantly explore and learn about their environment, memorizing the locations of pathways, obstacles, food and water, shelter, and other elements in their domain. They quickly detect new objects in their environment but do not fear them.

Damage and Damage Identification
When house mice live in or around structures, they almost always cause some degree of economic damage. In homes and commercial buildings, they may feed on various stored food items or pet foods. In addition, they usually contaminate foodstuffs with their urine, droppings, and hair. A single mouse eats only about 3 grams of food per day but destroys considerably more food than it consumes because of its habit of nibbling on many foods and discarding partially eaten items. Mice commonly damage containers and packaging materials in warehouses where food and feeds are stored.

House mice cause structural damage to buildings by their gnawing and nest-building activities. They may quickly cause extensive damage to insulation inside walls and attics in homes, apartments, offices, and commercial buildings. House mice often make homes in large electrical appliances, and here they may chew up wiring as well as insulation, resulting in short circuits which create fire hazards or other malfunctions that are expensive to repair. Mice may also damage stored items in attics, basements, garages, or museums. Damaged family heirlooms, paintings, books, documents, and other such items may be impossible to replace.

Mice carry many diseases that can be transmitted to humans. The presence of house mice can be determined by a number of signs: droppings, tracks, smudge marks, gnawing, sounds, visual sightings, nests, and odors.

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ACKNOWLEDGEMENTS
The above information was adapted from PREVENTION AND CONTROL OF WILDLIFE DAMAGE with permission of the editors, Scott E. Hygnstrom, Robert M. Timm, and Gary E. Larson (Cooperative Extension Division, Institute of Agriculture and Natural Resources University of Nebraska-Lincoln, United States Department of Agriculture Animal and Plant Health Inspection Service, Animal Damage Control, Great Plains Agricultural Council Wildlife Committee). It is will great gratitude and appreciation that we are able to pass along this useful information.