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Image
A house mouse. Photo by Donald Hobern (https://www.flickr.com/photos/dhobern/40924693714/). Shared under a Creative Commons license (CC BY 2.0).
COLUMBIA, Mo. – Temperatures are dropping, and that tiny mouse in the house looms large as pests make their way inside. University of Missouri Extension state wildlife and fisheries specialist Robert Pierce says it is time to prepare for the unwelcome houseguests.
“You won’t be the first person annoyed or outsmarted by a mouse or rat,” says Pierce. “These rodents have keen senses of taste, hearing, smell and touch.”
The why
House mice and Norway rats can contaminate an area with urine, saliva and droppings. They can transmit diseases such as salmonellosis (food poisoning) and swine dysentery, and they can carry ticks.
The biology
These rodents can multiply quickly. Mice can produce up to 8-10 litters per year with 5-6 young per litter, and rats can produce 3-6 litters of young each year, so populations can build up quickly. Within six weeks, they can create an army of tiny, scurrying nightmares. Fortunately, these species don’t ordinarily have long lifespans, as many animals prey on them, but even a few mice or rats in your home can cause lots of problems.
The how to
Give these rodents an inch and they will take a mile.
Mice can squeeze into the tiniest of spaces and through holes as little as ¼ inch across. Even more alarming, says Pierce, rats will gnaw and make their way into holes as small as half an inch.
Snap and trap
Although there are numerous rodenticides (toxic baits) on the market, Pierce advises against using them indoors, as the animal will often die behind a wall or in an enclosed area and will cause a terrible odor as they decompose. These products are best used outdoors and with a bait station that provides a safe location for rodents to consume the bait.
Pierce says the cheapest and most effective way to catch a mouse or a rat is with an old-fashioned wooden snap mousetrap. There are larger versions of the snap trap that will work for rats.
Placement is the key to success, he says. Put traps where rodent activity has been observed and on the floor adjacent to a wall or an edge. Use enough traps in an area so that the trapping effort will quickly be effective. If rats or mice are bait-shy, leave the trap unbaited for a few days so they become accustomed to the trap. Then apply the bait. Mice and rats often will travel in a linear fashion along a wall; however, they are excellent climbers and can run up any rough vertical surface, says Pierce.
Choosy mice choose PBJ minus the J
Use a light slather of peanut butter as a bait on the snap trap. Cheese and fruit are good second choices.
An ounce of prevention is the best cure. In other words, stop mice and rats from getting indoors in the first place, says Pierce. Use caulk to seal holes and gaps around windows, doors, dryer vents and electrical and gas lines.
Stuff larger entry points with copper wool (such as cleaning pads) that can’t be chewed through. Plastic, wood or cloth won’t keep mice at bay. Window and door screens that don’t have holes provide good barriers.
Clean the clutter
Remove safe havens near your house such as leaves, brush piles and trash. Clean up clutter outside and inside. Woodpiles and feeders for birds and wildlife are welcome mats for rodents. Seal garbage cans, bags of birdseed, livestock feeds and pet foods, which can attract mice.
Telltale signs
Mice leave droppings that look like dark pieces of rice. Norway rat droppings are larger. Rats are burrowing animals that can create entrance holes about 2 inches in diameter. Both species build nests that consist of fine, shredded, fibrous materials, and they may leave behind pieces of gnawed-up wood and food. Other signs include small gnawing marks and dark smudges and rub marks. These rodents are active throughout the day and night, and although you rarely see them, you may hear them moving behind your walls or smell their musky odor.