The Homeowners Column

The Homeowners Column

Keep out furry house guests - Mice

Photo of Sandra Mason

Sandra Mason
State Master Gardener Coordinator
slmason@illinois.edu

Guests come and go during the holidays. However Mickey, Minnie, or Mighty may have decided to stay since your home, garage or even your car is the perfect place to raise a family. Mice can quickly become unwanted guests. In a year one female mouse can have 5-10 litters with 5-6 young in each litter.

Of the several species of mice found in Illinois the species most likely to cause damage to our structures and food are house mouse, deer mouse and white-footed mouse. Mice will eat just about anything and also do damage by chewing electrical wires in houses or cars and wood in homes and garages. Blankets, clothes, paper, cardboard, and house insulation may be damaged as it is used for nesting material. Mice can also carry human disease.

House mice are small grey-brown rodents with long tails, large ears and black eyes. They are typically 5½ to 7 inches in length including the tail and weigh one-half ounce. House mice are not native to Illinois, but are very comfortable living with us.

Deer mice and white-footed mice are native to Illinois and are important food sources for wildlife such as fox, owls and hawks. They can become indoor residents as they search for a warm place to spend the winter. These mice appear gerbil-like to me with their grayish-brown to reddish-brown coats, white bellies and white feet. Their large, black eyes and large, nearly hairless ears give them cartoon cuteness. They are typically a bit larger than house mice. White-footed mice are found in homes near wooded areas whereas deer mice are more common near open areas such as farm fields and pastures.

Effective mouse control includes three elements: proper sanitation, mouse proof construction and population reduction. Proper sanitation includes reducing food and shelter. Keep debris piles, wood piles and stacked boards way from home foundation. Store indoor materials in tight-fitting hard plastic containers and if possible at least eight inches off the floor and one foot away from walls.

Also store bird and pet food in tight-fitting containers. Keep filled pet food bowls out for a short period. It's almost impossible to starve out mice, but controlling food access will reduce populations.

Mice can detect openings where warm air is escaping from buildings. In a convoluted way mice are doing you a favor by forcing you to make your home more energy efficient. Mice can enter through very small holes. Eliminate any openings larger than 3/16th of an inch. Eliminate gaps around pipes with steel wool and caulk or mortar. Larger openings can be closed using aluminum flashing.

Mouse populations can also be controlled using traps and toxicants. In most home situations traps are the best option for low mice populations. Traps do not contain pesticides and allow removal of the bodies.

Snap traps are the most common. Bait traps with peanut butter, caramel or nesting materials of cotton balls or cloth. Mice are most active before dawn and right after dusk. Place traps behind objects in dark places next to walls. Use several traps at no more than ten feet apart. Or just adopt a cat with a known reputation as a good mouser.

Box traps which capture the animal alive are not recommended for house mice since they are not native and relocating animals is very stressful to the animal and the likelihood of their survival is very low.

Electronic devices are also not recommended. Mice are very accustomed to living with people and our repeated noises. Little evidence shows the effectiveness of sound, magnetic, or vibrating devices at driving mice from buildings.

Check out UI Extension website Living with Wildlife in Illinois http://web.extension.illinois.edu/wildlife/ for more information.

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