The onset of cold weather with periods of unseasonably warm winter weather has coincided with increased reports of mice finding their way into homes in search of food and shelter. These small, furry intruders and the signs of their presence are showing up in cupboards, basements, food storage areas, kitchens, bathrooms and garages.
According to Terry Messmer, Utah State University Extension wildlife specialist, the intruders include both the common house mouse and the deer mouse. Generally the deer mouse can be found living far away from humans, but with recent unusual weather patterns and doors and windows being left open on occasion, mice are making their way inside.
Messmer said because they are most active at night, most mice can roam undetected throughout a house. Only the light sleeper may hear their scratching and rustling.
“If you start seeing them around in the daytime, this could indicate you have several mice in the house,” he said. “And mice have a very high reproductive rate. Within a matter of months, a pair of mice can produce several litters. These litters can also start producing mice within 2 months of birth.”
Mice are known as nibblers, Messmer said. They will eat a wide range of foods, but prefer those that are high in fats and sugars including chocolate, bacon, butter and nuts. Cat and dog food are also favorites. Mice get most of the water they need from the food they eat. In addition to nibbling on food, mice can cause structural damage with their chewing.
Mice also are constantly urinating and defecating, he said. The presence of their droppings and the musky smell of urine coming from cupboards or drawers are indicators that mice are around.
“The best way to control mice in the house is to keep them from getting in,” Messmer said. “Seal all holes and openings larger than one-quarter inch. Use heavy materials such as concrete mortar, sheet metal or heavy gauge hardware cloth. Beware of claims about devices that make high-pitched noises or produce electromagnetic fields to deter mice. In our experience, these devices don’t work.”
Make any food in the house as inaccessible as possible, he said. Store bulk foods in rodent-proof containers, and make sure any spilled food or crumbs are cleaned up. Do not leave pet food out. Lastly, that leftover cookie that ended up behind the couch cushion can feed a mouse for more than a week.
Because mice can carry diseases in addition to the other damage they cause, Messmer said to remove them from the house as quickly as possible once they are trapped. In most cases, mice can be easily caught using glue or wooden snap traps. Because they are adept at removing bait from single-trigger snap traps, consider using traps the have expanded or enlarged trigger platforms. Do not use rodenticides (poisons) to control mice in homes. Mice that feed on poison baits may die in the home, and as they start to decay, the resulting odor may cause additional problems.
“Mice have poor eyesight but excellent senses of touch and smell, so they tend to travel close to walls and other objects,” he said. “Therefore, traps should be set close to walls where mouse activity is likely. In most cases, plan on setting at least six or more traps in the house.”
To increase trap effectiveness, use small amounts of fresh bait. The best bait is peanut butter. Also, bait the traps without setting them for a day or so. When the bait has been taken, set the trap. Any mice trapped should be bagged and disposed of in an outside garbage container or buried.
For more information on mice, visit the USU Extension site at <a href=”https://extension.usu.edu/files/publications/publication/NR_WD_010.pdf” target=”_blank”>https://extension.usu.edu/files/publications/publication/NR_WD_010.pdf</a>.