Extension Educator, Horticulture
It's hard to believe an animal named Mickey, Minnie, or Mighty could be such a pesky, perennial pest in our homes. As the weather gets cooler, mice look for a cozy place to spend the winter and our houses are prime real estate. Spend time now getting your house ready for fall and keep the varmints out.
House mice are small grey rodents with long tails, large ears and black eyes. Sometimes you may find the occasional deer mouse indoors. They look more gerbil-like to me with their brown fur and very large eyes and ears.
The mighty mouse causes an estimated $20 million in damage to human and livestock food and structures. Mice will eat just about anything and will store extra food. They also do damage by chewing electrical wires in your house or car and wood in homes and garages. Blankets, clothes, paper, cardboard, and house insulation may be damaged as it is used for nesting material.
It doesn't take long to have a major mouse problem. In a year one female mouse can have 5-10 litters with 5-6 young in each litter.
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 away 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. Copper woven wire mesh is a bit more expensive, but does not rust as steel wool will and can easily be wedged into cracks. Larger openings can be closed using aluminum flashing or ¼ inch wire mesh.
Mouse populations can also be controlled using traps and toxicants. In most home situations traps are the best option. Traps do not contain pesticides and allow removal of the bodies. There is a certain art to trapping mice, but I doubt it will show up on an animal safari program.
Snap traps are the most commonly used. Ones with expanded triggers are the most successful. Bait traps with peanut butter, caramel or nesting materials of cotton balls or cloth. When first putting out traps, leave the traps unset until the bait has been taken at least once. This method eliminates the possibility of the mice developing trap shyness. 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. House mice 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.
Not only mice but insects such as multicolored Asian lady beetle, boxelder bugs and attic flies will try to make their way into our homes in fall. Eliminating openings will also help to keep out these unwanted house guests.