Signs You Have a Mouse in Your House

Mouse that's entered a house

All of the signs of mice in your home stem from different mouse needs. Mice sharpen their teeth on soft material, leaving behind gnaw marks. They leave droppings wherever they nest. They’ll damage containers to access food. Understanding mice needs helps you spot the signs of mice in your home.

Spotting signs of mice in your home is important because, in turn, the faster you spot them, the faster you can intercept and end possible mouse infestations before they get out of hand. Mice tend to reproduce indoors rather quickly, so you’ll have to act fast! Here are each of the common signs of mice in your home to watch out for, what they mean, and what you should do about them:

Droppings

Mouse droppings

Mouse droppings are dark brown or black, around ¼ to ½ an inch long, and shaped like a thin spindle, pill, pellet, or thin grain of rice. They usually look and feel dry and brittle. As droppings dry, they flake and break apart, which will make them look like dirt.

A single mouse can produce up to 1% of its weight in droppings in a single day. Mice tend to poop in straight lines because they follow set pathways to navigate through your home safely. Look for straight lines of rice-shaped droppings around baseboarding, wall corners, and under furniture. The more droppings you find, the more mice you probably have.

Gnaw Marks & Damaged Wiring

Container with mouse damage

Rodent incisors never stop growing. To compensate, mice have to teethe throughout their lives. They’re constantly gnawing on any soft material they can find, including wood, paper, cloth and other fabrics… and, unfortunately, electrical wiring. Over time, mice can leave behind distinctive gnaw marks on this material and even begin to cause dangerous damage.

Mice generally gnaw on soft materials at night, around where they nest and hide during the day. Look for damaged wires, chewed cardboard and other paper products, torn up fabric and furniture, ruined insulation, and gnawed wood, especially in any unfinished parts of your home such as your basement or crawl space. If you find damaged wiring, give us a call right away!

Damaged Food Containers

Mice eating noodles from a bag in a pantry

Mice need to eat. That means if mice are going to stay inside your home for any extended period of time, they have to eat inside your home, too. Mice are omnivorous and notoriously interested in quantity rather than quality. They’re even more interested in consistency. Mice want a food source they can return to time and time again.

Consequently, mice love to break into packaged food – particularly packaged food that you don’t use or deplete very quickly. Look for damaged dry goods such as bird seed, pet food, flour, nuts, seeds, and anything else you keep in dry storage. Mice dig their way inside food containers and help themselves as long as they can. The trick to keeping them from living near you perpetually is to make sure that isn’t long.

Nests

Mouse nest

Rodent nests aren’t exactly as elaborate as the bird’s nests you’re used to associating with the word. In fact, they probably won’t look “nest-like” at all. Mice build small nests out of any reclaimed soft material they’ve gnawed away. This could include paper, insulation, fabric, or pretty much any other scraps of garbage they can (literally) sink their teeth into.

Mice are nocturnal and spend most of their time sleeping or hiding in dark, sheltered areas. These areas also tend to be where they build their nests and raise their young. Look for small, dirty clumps of soft debris under furniture, in underutilized corners, under racks and shelving, and pretty much anywhere else where mice could sneak around and hide without fear of being bothered.

Dirty Wall Markings

Dirty wall markings left on the walls of a home by mice

Rodents actually have very poor eyesight. In order to move around your home safely, they tend to stick to paths they know, running their bodies along a wall or object to make sure they’re not lost. The longer mice stick to a particular path, the more of their body grease and dirt rubs off on the walls and objects they rub up against.

Mice generally run along the perimeter of the rooms they inhabit. Check for dark, greasy smudge marks along the baseboarding in your basement or closets. Look for fur, gnaw marks, and the other signs included on this list along the path as you follow it for more evidence of infestation.

 What to Do if You Have Mice

If you find any of these… ahem… telltale signs of mice infestation in your home, then it means the time to take action is now. The longer mice live in your home, the harder they are to remove.

The best way to take action is, of course, to give Griffin Pest Solutions a call right away. Our experts specialize in mouse control that keeps the repugnant rodents away for good. Let us know whenever you need our help, and we’ll be there faster than even the most enterprising mouse could make itself at home – no ifs, ants, or bugs!

Want a quick way to reference the signs of mice in your house while you’re tracking down your mice? Keep this trusty infographic with you and you’ll always know what to look for:

signs you have a mouse in your house

How Did I Get Mice?

Mouse peeking out of a small mouse hole in a home's wall next to an electric outlet

Mice can squeeze through any gap that’s at least ¼ of an inch wide–about the size of a dime! They find these gaps by following the smell of food or feeling of air pressure differentials created by drafts. Mice are very adept climbers, so they can reach gaps anywhere around your home.

After using tiny gaps to sneak inside, mice can reproduce all year as long as they have food. Mice had to sneak in originally, but many of the mice you find in your home were likely born there. The best way to keep mice out of your home for good is to seal off their access points. These are the four most common ways mice get inside homes and how you can mouseproof them.

Frames

Believe it or not, door and window frames are probably the access points mice use most. Wooden frames naturally warp and bend over time, creating small gaps between the window or door and the frame. Likewise, the weatherproofing wears down or unpeals. Eventually, tiny gaps appear between the door or window and frame or the walls and the frame. These gaps may not be large enough to see, but they’re large enough for mice to use.

Conduct a quick maintenance inspection on each of your door and window frames every spring and fall. Replace any weatherproofing that looks worn down or damaged. Check to make sure the doors and windows sit in the frame properly and don’t feel too tense or loose. Patch up any cracks or gaps you find around the wood itself using caulk. If you can feel a draft, it means your frame isn’t as secure as it should be. Find the gap sucking hot air out and patch it up.

Utility Lines

Utility lines are the pipes, wires, and vents bringing gas, electricity, heat, and plumbing into your home. All homes need to have small gaps in their walls to allow these utility lines inside. The problem is, mice can find these gaps by following the utility lines. They’ll sense heat given off by ventilation or hot water and follow that heat through the wall. Gaps between walls and utility lines may expand over time, making the gap an even more attractive access point.

Starting outside, walk the perimeter of your home looking for each area where a utility line enters the building. Look near your HVAC, your power meter, your sump pump, your light fixtures, and your outdoor faucets. If you see a visible gap between these pipes or wires and the wall, patch that gap with caulk. When you’re done outside, go inside and do the same thing. Replace these caulk barriers around once a season to make sure they don’t wear away.

A small gap between a basement's wall and its concrete floor. Mice often sneak through the space gaps like these create.

Subterranean Gaps

Over time, cracks and gaps may open up around the foundation, siding, or the baseboarding of your home. These could occur because of weather damage, wood rot, or natural wear-and-tear. However they happen, small gaps and cracks around your home’s foundation start to create drafts. These kinds of drafts are particularly common in unfinished basements. Mice are very sensitive to temperature and pressure differentials. When they sense the hot air shooting out of gaps in a home, they’ll follow it inside.

Start in your basement or lowest level this time. Look for cracks and gaps in the floor and ceiling. Pay particular attention to corners, windows, baseboard, and frames. Seal any gaps you can find with silicone caulk or steel wool. Remember: if a crack or gap is big enough to see, it’s probably big enough for mice to use. Just like before, when you’re done inside you should look for cracks and gaps outside, too.

Roofing

Mice are surprisingly adept climbers. Most mice are capable of climbing most homes without much difficulty by finding downspouts, wires, or other holds. Mice can also access rooftops by climbing up nearby trees or bushes and crawling along overhanging branches. Unfortunately, the fact that mice can climb so well means no access point is safe. Mice don’t just sneak inside from the ground; they could be sneaking in from the roof, too!

Even worse, roofs tend to have all kinds of neglected access points. Mice can exploit rotting shingles, ventilation outlets that aren’t covered, chimneys, cracked gutters, and more. If you have roofing damage, mice will likely use that damage as a means of entering your home. You should have your roof inspected at least once every few years. Check for cracked shingles, rot, and other possible damage. You should also always block your vents and chimneys with mesh.

 

The best way to prevent mouse infestations is to continuously monitor and block off access points. Check each of the most vulnerable areas every spring and fall to make sure you’re still covered. If you stay on top of your access point maintenance, you’ll keep mice from infesting your home for good.

If you already have a mouse infestation inside your home, even blocking off access points won’t help right away. Instead, you’ll have to call the pros at Griffin Pest Solutions. We can drive out mice and make sure they can’t get in again. Mouse season is starting right now, so if you think you have a problem, get in touch right away! We’ll help make sure you have a rodent-free fall.