There’s a scritching sound in the darkened bedroom. Your eyes spring open, your breathing rapid and shallow, with every muscle tensed and ready to run...only to find that all is still and silent. You start to drift back to sleep.
Every nerve in your body is now on high alert, and you turn on the light just in time to see a flash of fur dart into the crack under your closet door. You scream an undignified “YEEAAARRGGEETTTOUTTTTT,” which, roughly translated from panicked shrieking, means: “Hello, you are a mouse. Please leave.”
Do I have a mouse in the house?
“Something I’ve noted over the years is that you know someone has a mouse when you hear the very distinct scream the person makes when they’ve seen a mouse.” Michelle Niedermeier jokes. “Male, female, old, young—it's the same screech.”
Niedermeier works with the Pennsylvania Integrated Pest Management Program, helping communities deal with pest problems. She says that often, for her, the first sign of a mouse is seeing the mouse itself scurry across the floor.
But there are other signs of an infestation that you should be aware of, especially in areas of the house you only visit infrequently, such as attics or crawlspaces.
One of the most obvious signs of a mouse infestation is feces. The poop of a typical house mouse is only a few millimeters long, black, and pellet-like. Mice poop a lot, and they poop just about everywhere, so seeing their droppings is usually a good sign that the rodents have taken up residence.
If an infestation goes on for long enough, then you might start to notice a distinct and unpleasant smell, or even some strange markings on your walls.
“Where mice go, they leave scent, and they leave a grease trail too,” says Jeff Schalau, an extension agent with The University of Arizona cooperative extension. Near baseboards and along walls, this grease trail resembles the smudges from handprints on a painted surface. It appears when a mouse rubs against the wall, leaving behind dirt and oils from its fur. Mice tend to avoid open spaces, and will usually travel as close to the wall as possible, which makes their trails easy to predict.
Why should I care?
In addition to the unwanted gross-out factor, mice (at least in relation to humans) are not a healthy addition to a home.
“Mice are a health concern,” Niedermeier says. “They spread disease, they trigger asthma, and so having a mouse in your house is a real health issue.”
They also tend to carry foodborne diseases like salmonella. And since mice enjoy noshing on the same foods that people and pets do, they have the potential to spread diseases onto our food and food preparation surfaces.
And that’s not the only illness that these fuzzy creatures can spread. “Hantavirus is a serious issue out here in the west,” Schalau says. Hantavirus Pulmonary Syndrome, carried by rodents including mice, can be fatal.
So if you find a mouse, don't try cohabiting. “As soon as you identify a problem, take action,” Schalau says. Otherwise, the infestation will only grow—and you'll soon have to contend with multiple generations of rodents. According to Schalau, “Their reproductive potential is off the charts. At the first sign of any mice inside your house, you need to get on it.”
The best ways to get rid of mice
Unlike some other pests, a mouse infestation is one that you can take care of yourself. There’s no need to call an exterminator—just screw your courage to the sticking place and get to work.
Start by making your home an unattractive crash pad for any tiny guests.
“It all boils down to food, water, and shelter,” Niedermeier says. Cut off those three things, and you’ll make your home a lot less attractive to mice.
The problem is that mice are resourceful. For water, they can take advantage of leaks that you might not even know exist, and for shelter, they can make use of just about any kind of clutter or hole. That makes food the most important factor to tackle.
“Eliminating food is paramount to getting rid of a mouse problem,” Niedermeier says.
Start by cleaning up any crumbs or food debris on surfaces and floors. When you cook, promptly clean dirty dishes instead of letting them sit out. Store food in places that mice can’t reach, like the refrigerator, or inside containers they cannot nibble through, such as glass or very sturdy plastic. And don’t forget about your pets' supply. Only put out the amount of food that a pet will eat in one sitting. While Fifi might like grazing on kibble throughout the day, so do mice.
Now that you’ve made your home unfriendly to mice, it’s time to bar the door. Literally. Mice can enter the house through the same entrances you do, so add a door sweep or barrier to any exterior doors.
Then it’s time to block up all the unconventional entrance and exit points. If you happen to see a mouse, pay attention to where it runs, and stay on the lookout for any holes or cracks.
“If you can stick a regular old pencil in a hole, a mouse can get through,” Niedermeier says. She explains that the largest part of a mouse is its tiny skull, which is usually only the width of a pencil. “If their head can get through, the rest of their body can get through as well,” she adds.
Close up any holes that you see, and don’t forget about the holes that you’ve helped put in. Holes around pipes or wiring are often overlooked, but can act as a mouse superhighway system through your home.
When you fill in those holes, use high-quality materials that will last for a very long time. In the end, it will save you a lot of work. Niedermeier recommends using silicone caulk or stainless steel or copper mesh—think a pot scrubber—to block any openings. Silicone lasts for a longer time than latex caulk, and unlike steel wool, copper and stainless steel don’t rust.
“You really only want to do this job once,” Niedermeier says.
Yeah, yeah, but what about the mice?
So you’ve cleaned up, boxed up, and sealed up your home—but there are still some mice inside. Now, it’s time to get rid of the stalwarts that remain. But what's the best way to get rid of mice?
For starters, as much as you might want to, you can’t just take them outside. Mice have excellent senses of direction, and even moving them some distance from your house isn’t enough to get rid of them. In experiments, they find their way home quickly, even heading through obstacles to get back to their residences. The best way to get rid of mice from your home, unfortunately, is to kill them.
The most effective method is a trap, baited with tasty morsels like peanut butter, oats, or dried fruit. Place them along baseboards and walls, where mice prefer to travel, with the bait directly in their path. Simple wood and wire snap traps are a classic for a reason. They work fast, they’re effective, they’re cheap, and they’re reusable. When in doubt, this is a good first option for any home with a mouse problem.
More modern plastic snap traps, which look something like a binder clip, are also effective. Like the wooden snap traps, the plastic ones are easy to set up and use. Between the two, it’s mostly a matter of personal preference.
If you have a pet, be sure to place the traps where your pet can’t reach. If this isn't possible, Schalau recommends placing a sturdy box with a mouse sized hole in it along the wall and over the trap. This will allow the mouse to reach the bait, while keeping your pet safe.
Another effective and humane option is an electric box trap, which can be baited just like a snap trap. The battery-powered machine has an opening that mice can run into to try and catch the bait. When a mouse enters the box, it steps on a plate that carries a current and is instantly electrocuted. Then, a small light begins flashing to indicate that the trap has caught a mouse and should be re-set. Electric box traps are good for homes with pets, because they are completely enclosed, so no dog or cat can get to the charged plate. In addition, they leave very little mess, which makes them easy to clean. The downside is that you do need to make sure the batteries are regularly charged, and they cost considerably more than a snap trap.
What not to do
Not all mouse-killing methods are created equal. Though poison is frequently used, experts do not recommend this option. While it will kill the mice, poison can also kill any animals that might feed on mouse carcasses. It can also inadvertently poison pets.
And there’s another downside. Most poisons don’t work instantly, and with good reason: Manufacturers don’t want mice to become gun-shy of poisoned bait. So what often happens is that a mouse eats a poison pellet, walks back to its nest, and only then dies. Unfortunately, mice like tiny holes, and often take up residence in hard-to-reach places like walls.
Trust. You do not want to smell a dead mouse for months as it slowly decays inside your walls. Don’t do it.
Another popular option on the market is glue traps, which stick to the bodies of any mice that walk over the trap. Theoretically, this should immobilize the mouse. But starving to death while stuck to a piece of cardboard is not a great or humane way to go. And few people are willing to kill the mouse by hand. That is, if the trap actually works.
“The glue, though it's sticky, is not sticky enough,” Niedermeier says. Older, stronger mice—which are more likely to be breeding and creating a mouse problem—can often pull themselves out of the glue traps, sometimes with a very gruesome effect. “They are ready, willing, and able to gnaw off their own arm to get out of it," she explains. "It’s more humane to use a snap trap.”
Once you’ve closed off access to your food, water, and shelter, sealed entrances and exits, and killed any interlopers unfortunate enough to remain in your domain, it’s time to clean up.
If you used traps, you should keep your hands covered while you dispose of mouse carcasses in the trash. Use disposable gloves, a plastic bag, or even sturdy leather work gloves to keep a safe distance between you and the mouse. Remember, mice can harbor diseases, so you want to be cautious as you handle their bodies.
You can also take the bodies outside if you live in a rural area, but be sure to put the remains in an area far away from your house, where pets won’t be likely to bring them back in, and they won’t attract additional unwanted scavengers.
Also, take the opportunity to clean up any mouse urine or droppings, wearing a face mask if you are allergic or have asthma. The CDC says that the safest way to clean up after mice is to wear gloves and spray the droppings with diluted bleach before wiping up the waste. Needless to say, washing any clothing or bedding that has been pooped on is always a good idea. And don’t forget to wash your hands afterwards.
Whew. You’re all set. Sleep the sleep of the content knowing that you have a mouse-free house.