Mice or Rats? How to Tell What’s in Your Attic

The quickest way to tell mice from rats is the droppings: mouse droppings are tiny, about the size of a grain of rice, while rat droppings are roughly three times longer. The sounds, the size of the holes they chew, and where you find signs all add clues. Here’s how to figure out what’s in your attic or walls, why it matters, and what to do next, just as Middle Tennessee rodents start moving indoors for winter.

Mice vs. Rats at a Glance

• Droppings: mice leave pellets about 1/8 to 1/4 inch long with pointed ends, often scattered. Rat droppings are about 1/2 to 3/4 inch. Norway rat droppings are blunt on the ends, while roof rat droppings are more pointed.
• Entry holes: a mouse can squeeze through a hole about the size of a dime. A rat needs one about the size of a quarter.
• Gnaw marks: mice leave small, clean-cut holes. Rats leave larger holes with rough, torn edges.
• Size: adult house mice are small enough to fit in your palm. Rats are much bigger, with thick, scaly tails.
• Sounds: both are most active at night. Mice tend to sound like light scratching or scurrying. Rats are heavier and can sound like thumping or dragging.

The Rodents Middle Tennessee Homeowners See Most

• House mice: the most common rodent inside homes. They nest in walls, cabinets, attics, and stored items, shredding paper and insulation for bedding. Read more about the most common mice in Tennessee.
• Norway rats: large, heavy-bodied rats that usually burrow at ground level. They tend to show up in crawl spaces, basements, garages, and along foundations.
• Roof rats: sleeker, agile climbers that travel along tree limbs, fences, and utility lines. If you hear activity in the attic or upper walls, roof rats are a real possibility.

What Are You Hearing in the Attic?

Noises overhead at night are one of the most common reasons homeowners call us in the fall. A few clues help narrow it down:

• Light, quick scratching in the walls or ceiling usually points to mice.
• Heavier movement or thumps, especially in the attic, can mean rats.
• Noise right at dawn or dusk can also be squirrels, which are active during the day, unlike most rodents.

Sound alone can fool you. Droppings and gnaw marks are much more reliable, so take a flashlight into the attic and look along beams, near insulation, and around stored boxes.

Why It Matters Which One You Have

Mice and rats behave differently, so the fix is different too. Mice can get through dime-sized gaps, which means sealing has to be extra thorough. Rats are bigger and more cautious around new objects like traps, and Norway rats often come up from burrows outside. Getting the identification right means the right traps or bait in the right places, and the right entry points sealed.

Other Signs of Rodents

• Greasy rub marks along walls and beams where rodents travel the same path again and again
• Nests of shredded paper, fabric, or insulation in attics, wall voids, and storage
• Chewed food packaging in the pantry or garage
• Chewed wiring, which is a fire risk, not just a nuisance
• A musky odor in closed spaces with heavy activity

Why Rodents Move In During the Fall

As temperatures drop from September into November, mice and rats look for warm shelter close to food and water, and our homes check every box. That’s why fall is the best time to seal entry points, before rodents settle in for the winter.

How to Clean Up Droppings Safely

Rodent droppings, urine, and nesting material can carry germs that become airborne if you disturb them. The CDC recommends:

• Don’t sweep or vacuum droppings, urine, or nests.
• Wear gloves, then spray the area with a bleach solution or an EPA-registered disinfectant until it’s very wet.
• Let it soak for 5 minutes, or as the disinfectant label directs.
• Wipe it up with paper towels, then clean the surrounding area with more disinfectant.

For a large infestation, or droppings in an attic or crawl space, let a professional handle it.

How to Keep Mice and Rats Out

• Seal gaps around pipes, wires, vents, and the foundation. Remember, a mouse only needs a dime-sized opening.
• Fix door sweeps and garage door seals so there’s no gap at the bottom.
• Trim tree branches back from the roof to cut off roof rat highways.
• Store food, pet food, and birdseed in sealed containers.
• Reduce clutter in attics, garages, and basements, where rodents nest.
• Keep crawl spaces dry, since moisture draws rodents and the insects they eat. Our crawl space services can help.

Setting traps yourself? Our guide on how to set a mousetrap walks you through it.

How U.S. Pest Handles Rodents

Our Pest Pros identify what you’re dealing with, find how they’re getting in, seal those entry points, and treat inside and out. Rodent control is part of our general pest control, so an existing problem is handled in your first, more thorough treatment, and regular visits help keep rodents from coming back. Large outdoor bait stations are available as an add-on. Learn more about our rodent control.

Mice vs. Rats FAQs

Sources: CDC, How to Clean Up After Rodents and University of Kentucky Cooperative Extension.

Hearing Something in the Walls?

Call 615-590-1260 or schedule a free inspection, and a Pest Pro will find out what it is and how it’s getting in.