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Mice in the attic. You know they’re up there because you hear the scratching at 2 AM, or you’ve spotted the droppings along your rafters, or you’ve found chewed insulation that looks like confetti. Whatever tipped you off, you’re done waiting for them to leave on their own (they won’t).
This isn’t about coexisting. It’s about eviction. Here’s how to get them out and keep them out.
1. Seal Entry Points with Foam, Steel Wool, or Cement
This is the single most important step. You can trap every mouse in your attic today and three more will move in tomorrow if you leave the door open.
Mice can squeeze through openings the size of a dime. Check along your roofline, where utilities enter the house, around vents and pipes, and anywhere two different building materials meet. Look for gaps, cracks, and holes.
For small gaps (under 1 cm), pack tightly with steel wool and seal over it with expanding foam. Mice can chew through foam alone but they won’t chew through steel wool. For larger holes, use hardware cloth (wire mesh) secured with screws, then seal edges with cement or caulk. Check your soffits, eaves, and fascia boards while you’re at it.
Do this before you start trapping. Otherwise you’re playing catch-up forever.
2. Use Snap Traps Along Travel Routes
Snap traps work. Bait stations are fine if you want to spend more money, but a basic Victor snap trap baited with peanut butter will kill mice just as dead.
Mice don’t wander randomly. They follow walls and edges because they have terrible eyesight. Place traps perpendicular to walls with the trigger end facing the wall, so mice run directly into them. Check rafters, along baseboards, near any stored boxes, and in corners.
Use at least six traps. More if your attic is large. Check them daily and reset as needed. Wear gloves when handling dead mice and dispose of them in sealed bags.
3. Place Bait Stations 8-12 Feet Apart
If you’d rather use poison bait than traps, bait stations are the safer option (especially if you have pets or kids who might get into the attic).
Space stations 8 to 12 feet apart along walls and near rafters. Place them where you’ve seen droppings or along obvious travel paths. Tomcat, d-CON, and JT Eaton all make reliable stations.
Refresh the bait daily for at least 15 days. Mice are cautious eaters and won’t always take bait immediately. If the bait disappears, refill it. If it’s untouched after a week, move the station to a different spot.
One warning: poisoned mice sometimes die inside walls or insulation. If you can’t tolerate the smell of decomposition, stick with traps.
4. Use Peppermint or Ammonia Repellent Spray
Mice hate strong smells. Peppermint oil and ammonia are two scents that actually work as repellents (not as well as sealing holes, but they help).
For peppermint: mix 10-15 drops of pure peppermint essential oil with water in a spray bottle. Spray along baseboards, near entry points, and anywhere you’ve seen activity. Reapply every few days because the scent fades.
For ammonia: soak cotton balls in ammonia and place them in shallow dishes around the attic. The smell mimics predator urine and makes mice nervous. Replace weekly. Don’t use ammonia if your attic has poor ventilation or if you’ll be working up there regularly (the fumes are unpleasant).
Neither method will eliminate an active infestation on its own, but they make your attic less appealing to new arrivals.
5. Set Ultrasonic Repellers on High-Traffic Areas
Ultrasonic repellers emit high-frequency sound waves that supposedly irritate rodents. The evidence is mixed. Some people swear by them. Others say they’re useless.
If you try them, go with a model that has variable frequencies (mice can habituate to a single tone). Plug them in near entry points and along walls. Give it two weeks. If you’re still seeing fresh droppings, don’t waste more time on them.
They’re not a substitute for sealing holes or trapping, but they’re a low-effort addition that might tip the scales if you’re borderline.
6. Trim Tree Branches 2 Feet from the House
Mice are decent climbers. If you have tree branches touching or overhanging your roof, you’ve built them a highway straight to your attic.
Trim any branches within 2 feet of your roofline. Go further if you can. While you’re at it, check for vines or overgrown shrubs that touch the house. Ivy looks nice but it’s a ladder for rodents.
This won’t evict the mice already inside, but it closes one of the easiest access routes.
7. Move Firewood and Lumber Away from Exterior Walls
Stacked firewood, lumber piles, and yard debris create shelter right next to your house. Mice nest there, then move indoors when it gets cold.
Move wood piles at least 20 feet from your foundation. Store lumber off the ground on pallets or racks. Clear leaf piles, brush, and tall grass from around the base of your house.
The more you eliminate outdoor hiding spots, the fewer mice will be hanging around looking for a way in.
8. Store Attic Items in Sealed Plastic Bins
Cardboard boxes are mouse condos. They chew through them for nesting material, nest inside them, and use them as cover while they travel.
Replace cardboard with hard plastic bins with tight-fitting lids. Rubbermaid, Sterilite, whatever. Just make sure the lids seal properly. This protects your stuff and removes hiding spots.
If you have fabric, old clothes, or holiday decorations up there, those are especially attractive for nesting. Seal them up or get them out of the attic entirely.
9. Add a Chimney Cap and Close the Fireplace Damper
Open chimneys are an invitation. Mice (and squirrels, and birds) will climb down uncapped chimneys and end up in your attic or living space.
Install a metal chimney cap with mesh screening. It keeps out rodents and prevents rain from getting in. They’re not expensive and most hardware stores carry them.
If you have a fireplace, keep the damper closed when it’s not in use. Mice can climb down flues just as easily as chimneys.
10. Use Dry Ice to Suffocate Mice in Nests
Dry ice is carbon dioxide in solid form. When it sublimates (turns to gas), it displaces oxygen. If you can locate an active nest, you can use dry ice to kill the mice inside without poison or traps.
Place a pound of dry ice near the nest entrance, ideally sealing off other exits with cardboard or foam. As the CO2 spreads, the mice suffocate quickly and painlessly. This works best in confined spaces like wall voids or attic corners where the gas can concentrate.
Wear gloves when handling dry ice (it causes frostbite). Ventilate the attic afterward. And obviously don’t use this method if you’ll be working in the attic at the same time.
11. Set Up a Live Trap and Relocate (If You’re Feeling Generous)
Live traps catch mice without killing them. You bait the trap, the mouse walks in, the door closes, and you release it somewhere far from your house.
This is the least effective method on this list. Relocated mice often die anyway (unfamiliar territory, predators, lack of shelter). And you have to drive them at least a mile away or they’ll just come back.
But if you can’t stomach snap traps and you’re dealing with one or two mice (not an infestation), it’s an option. Use a Havahart or similar brand. Check the trap every few hours. Release the mouse in a wooded area with natural cover.
Don’t use glue traps. They’re inhumane and mice often chew their own legs off trying to escape.
What Happens If You Ignore Them
Mice breed fast. One female can have 5-10 litters per year, with 5-6 pups per litter. Two mice can turn into fifty in six months.
They’ll chew wiring (fire hazard), destroy insulation, contaminate your attic with droppings and urine (hantavirus risk), and eventually find their way into your living space. Ignoring the problem makes it exponentially worse.
The good news: you caught it. Now deal with it.
Final Notes
Start with sealing entry points and setting traps. Those two steps will handle 90% of the problem. Add repellents, exterior maintenance, and storage changes to prevent repeat infestations.
Check your attic every few weeks for fresh droppings. If you see none after a month, you’ve won. If you’re still seeing activity after two weeks of trapping, you either missed entry points or the infestation is larger than you thought. At that point, call a pest control professional. They have better tools and more experience finding hidden access points.
You don’t have to live with mice in your attic. You just have to be more stubborn than they are.