Something's In the Attic: How to Tell What It Is and What to Do

The first time you hear something moving above the bedroom ceiling, you'll try to convince yourself it's the house settling. It's not. Once the scratching, scampering, or thumping is loud enough to wake you up, you have a resident and you need to identify it, because the trapping approach and the exclusion work are completely different for each species.

Listen to when it's active

The timing of the noise is your first clue.

Roughly an hour after sunset and again around dawn, with fast scampering and light scratching: mice or roof rats. Both are nocturnal and both move quickly across insulation.

During the day, especially morning and late afternoon, with heavier scampering and occasional running: squirrels. Squirrels are strictly daytime animals. If your attic goes quiet at sunset and loud at 8 a.m., that's a squirrel.

At night, with slow, heavy movement, occasional thumps, and sometimes vocalizations — chirps, growls, or a raccoon-like chittering: raccoons. Often a mother raccoon with kits.

At dusk, with a distinct high-pitched squeaking and the sound of many small bodies moving at once: bats. You'll often see them exiting at sunset from a specific point on the exterior.

Slow scratching at night, sometimes a distinct 'sneezing' or huffing sound: opossums. Less common but not rare in the southern half of the country.

Then look for the damage

Get in the attic during the day with a flashlight and look at the insulation. Droppings tell you the species almost every time.

Rice-grain-sized, dark, and scattered: mice.

Small raisin-sized, blunt on the ends, in linear runs: rats.

Larger, oval, in localized piles: squirrels.

Very large, tubular, in a designated latrine spot: raccoons or opossums. Raccoon latrines can carry roundworm and should never be disturbed without a mask and gloves.

Tiny black flecks that crumble to powder: bat guano. Bats are federally and often state-protected and require a licensed operator to remove — do not attempt DIY.

Why the playbook differs

For mice and rats, the treatment is snap traps and bait stations combined with aggressive exclusion — sealing every gap larger than a quarter inch. Rodents can squeeze through openings much smaller than they look. You have to find and seal the entry point or new rodents will re-populate within weeks.

For squirrels, snap traps and bait stations are the wrong tools. Squirrels are trapped in live cages and released or handled per local law, and the entry point (usually a chewed hole in a gable vent, soffit, or eave) has to be sealed with metal flashing, not caulk — they'll chew right through anything else. If it's spring or late summer, there are almost certainly babies in the nest and sealing the mother out condemns them to die in your wall. A licensed operator times exclusion around the breeding cycle.

For raccoons, this is a wildlife control job, full stop. Mother raccoons will tear through drywall, roof decking, and soffits to get to their kits if you seal them out. Trapping and hand-removal of the kits is the only humane and effective approach, and in many states it's illegal for a homeowner to do it themselves.

For bats, do not seal them out during summer maternity season — the young cannot fly and will die inside your walls. Bat exclusion is done with one-way excluders in fall or early spring, by licensed operators.

For opossums, they're usually transient and often leave on their own. If they don't, live-trapping and exclusion is straightforward.

The mistake homeowners make

The single most common mistake is starting with poison. Poisoning a rodent, squirrel, or raccoon inside your attic guarantees a decomposing animal in your insulation, which will smell for weeks and attract flies and dermestid beetles. Trap and remove; then, and only then, seal the house.

If it's been in the attic more than a few weeks, plan on replacing contaminated insulation as part of the cleanup. Droppings, urine, and shed hair are health hazards and shouldn't be left in place after the animal is out.