Is That a Mouse Nest Inside My Wall?

By Chris Williams on January 22, 2014.

House mouse nest in wallQuestion

I had to open up a wall void in our laundry room to run some electrical lines and I found a strange ball of fuzz and grass and other debris all wadded up in the void space. Is that some kind of animal’s nest? If so, I’d like to know how it got there. If it’s not a nest, do you have any idea what it is?


I think it probably is a nest. You don’t say how big the ball is, but I would guess it’s the nest of either a house mouse or a deer mouse, both of which commonly nest in structures. A house mouse nest is usually a loose ball of materials, about the size of a grapefruit.  In your case, the nest is probably shaped to fit the void. A deer mouse nest is slightly larger than a house mouse nest and can be close to a foot in diameter. Both mice make nests of whatever is soft and pliable, and available: shredded paper or fabric, bits of Kleenex or paper towel, dried plants, leaves, string, feathers, bits of insulation, furniture or mattress stuffing, and so on. If you look more closely at the nest ball, I bet you’ll see that at least part of it is made up of dryer lint which would be accessible in the laundry room.

Both mice tend to hoard food in their nests. You might find bits of seeds, nuts, or even pet food near the void nest. Both house mice and deer mice urinate and defecate directly into or next to their nests, so you might see (or smell) that, too.

How Did Mice Get In My House?

It’s easy for mice to get into your home and then into a wall or ceiling void. Mice typically travel through walls and ceilings by following pipe chases or electrical lines. Mice could enter the wall void through any kind of tiny gap behind baseboards or through openings around utility lines that enter the wall, or from ceiling voids. You might find an edge or a corner where mice have gnawed to make a bigger opening. If you see dark, oily smudges around that opening, you’ve found a mouse hole.

A laundry room is a fairly common place to find evidence of mice because it is usually on the lowest level and has access to outside through patio doors, foundation vents, and through pipes and lines that run to the outside foundation. A laundry room is also quiet much of the time, has direct access to water, and maybe also access to food if you feed the dog there!

Is the Nest Still Active?

The nest could have been in the wall for some time and long abandoned, or it still could be in use. Without seeing mice or finding young in the nest, it could be hard to tell if mice are still using it. You can get some clues from mouse droppings found in or near the nest. Fresh droppings are black and soft with a texture like putty. Old droppings are grayer and dry. If you squeeze an older dropping, it will crumble.

If you have reason to believe that you have mice in your home, give Colonial a call. Our technicians will inspect for more evidence of mice and can set up a mouse control program for your home. We can also mouse-proof your home by sealing and reinforcing areas where mice enter.



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