Signs of Mice In Your Attic

By Chris Williams on February 27, 2015.

Mouse trap set up in attic

Mouse trap set up in attic.

John Maher:  Hi. I’m John Maher. Today, I’m here with Scott Winsper of Colonial Pest Control. Scott is a Wildlife Technician. Today, we’re talking about mice in the attic. Welcome, Scott.

Scott Winsper:  How we doing?

Signs of Mice in Your Attic

John:  Good. Scott, what are some signs of mice in an attic?

Scott:  Well, there’s a few things you can look for. Tunnel holes through your blown insulation, about the size of a quarters when you look around. There’ll also be some run lines running from the back end of your socket areas, where they’ll be going from one corner to the other corner.

John:  What does that look like, run lines?

Scott:  Run lines will probably look like — where the insulation’s been pushed down, and you actually look like a trail. If you’re walking through the woods in the snow and you see a certain trail, it’s the same thing with the insulation where they’ve been going back and forth to one area. You’ll see where the insulation is pushed down.

Mice Damage in Attics

John:  OK. What damage can mice cause once they’re inside my attic?

Scott:  There are several damages they can do. Your Romex wire, where your electricity comes into your attic, they will chew on that. They can cause a fire or cause a problem if that is chewed. Other thing’s where they can damage your insulation — with their urine, with their fecal matter in those areas, staining on your sheet rock, those are several things that mice will do in their attic and basement areas.

John:  Do mice prefer nesting in a certain type of insulation or does it not matter what type it is?

Scott:  Anything that gives them a nice, warm harborage area. Blown insulation’s good. Bat insulation’s good. Those are several things that they can tunnel in through and stay nice and warm and make a bedding out of.

Other Signs of Mice

John:  Should I look for anything besides the mice themselves to identify a mouse problem?

Scott:  Absolutely. Mice are kind of dirty. They like to leave rub stains where they come and go. Especially if you go in your basement areas, where you see your Romex wires running against the sill plates, mice will run those sill plates. What they do is, when they’re running, they’re actually using their fur against the side of those Romex wires or your sill plates, and they’ll leave stains.

There will be black rub marks. Good areas to look for where those rub marks are — go where your electrical panel is. Take those areas, look at your wires, where they’re coming up from the floors, where they’re going from left to right. Take a look at them. See if there’s any rub stains like that.

Other things you can look for is — go near your water tanks, your heaters. Anything that has a nice and warm area, mice are going to tend to. Those are areas you’re going to look for. You’re going to look for fecal matter, mouse droppings, any of that congregating in those warm areas, and that’s going to tell you if you have mice or not.

How to Get Mice Out of the Attic

John:  Once I’ve discovered that I do have mice in my attic, what are some of the things that I can do to get them out of there?

Scott:  First, I recommend calling a professional and taking a look at it. If you’re looking to do something for yourself, then several things you can do — you can trap using traps, or you can use a baiting in your attic. But that’s a band‑aid, it’s not a permanent fix.

A permanent fix is to look at your outside situation, your foundations, your roof junctures, your chimney areas. Those are areas where mice are going to come in. Those are the areas you want to address. You can constantly trap mice all winter long, during the spring, during the summer, but you’re going to constantly do it. When you’re looking for a solution to your problem, exclusion’s where to go.

John:  That’s great information, Scott. Thanks very much for talking to me today.

John:  For more information, you can visit the Colonial Pest Control website at or call 1‑800‑525‑8084. That’s 1‑800‑525‑8084.

Photo credit: John Loo / Foter / CC BY

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