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How do I keep mice out of my house?

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House mice are considered one of the most troublesome and economically important rodents in North America. Originally a native of Asia, they arrived in North America with early settlers. They are very adaptable and frequently live in close association with humans. They are probably the most common wildlife species in towns and cities.

With the onset of cold weather, mice migrate to structures as they search for food and shelter. They will eat a wide range of food, but prefer foods high in fat and sugar. Some favorites include chocolate, bacon, butter and nuts. Most water requirements are filled by the food they eat.

Because they are most active at night, mice can roam undetected throughout a household. If you see them during the daytime, this could indicate you have several mice in the house. Mice have a high reproductive rate. Within a matter of months, a pair of mice can produce several litters. With abundant food, each litter can have 10-12 young. These litters can then begin producing mice within two months of birth.

In addition to nibbling on food, mice can nibble and cause structural damage. They also regularly urinate and defecate. The presence of droppings and the musky smell of urine coming from cupboards or drawers is also an indicator that you have mice in the house.

To prevent mice from turning your house into their house, consider these tips.

The best control method is to prevent them from getting in. To exclude mice from structures, seal all holes and openings that are larger than one-fourth inch. Use heavy materials such as concrete mortar, sheet metal or heavy gauge hardware cloth. Also, be aware of open doors to garages, houses, barns or other structures. These are open invitations to mice. Make food in the house as inaccessible as possible. Store bulk foods in rodent-proof containers. Make sure spilled food items and crumbs are cleaned up. A leftover cookie behind the couch cushion can feed a mouse for more than a week. In most cases, mice can be easily caught using glue or wooden snap traps. Because mice have poor eyesight but excellent senses of touch and smell, they tend to travel close to walls and other objects. Thus, traps should be set close to walls where mouse activity is seen. For effective control, set at least six or more traps in the house. To increase effectiveness, use small amounts of fresh bait. Peanut butter and chocolate work well as bait. Do not use cheese since it tends to go rancid quickly, thus losing its attractiveness as a bait. Also, you may want to bait the traps without setting them for a day or so. When you notice the bait has been taken, set the trap. Because mice can carry diseases, it is important to remove them from the house as quickly as possible. They should be bagged and disposed of in an outside garbage container or buried.

Do not use rodenticides (poisons) to control mice in homes. Mice that feed on poison baits may die in the home. As they start to decay, the resulting odor may cause further problems. Devices that repel mice using ultrasonic or electromagnetic waves are advertised widely this time of year; however, there is no scientific evidence to support manufacturer claims that these devices work. For more information, contact you local county Extension office for a copy of the Extension Bulletin “Mice” or visit the USU Extension Web site at http://www.extension.usu.

Posted on 17 Sep 2004

Terry Messmer
Professor & Wildlife Resource Specialist

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