Published October 26, 2026. Read time: 11 min.
Quick answer
Scratching in the walls at night on Long Island is almost always mice, because house mice, white-footed mice and deer mice are nocturnal and move into buildings as the nights turn cold in October. Light, fast skittering and faint gnawing after dark means mice. Heavier scurrying with thumps after dark, usually low in the house, means Norway rats. Scratching in the attic in the first hours after dawn and before dusk means gray squirrels, which are active in daytime. Slow, heavy movement overhead at night, with dragging or a baby-like chatter, means a raccoon. The fix is the same order every time: identify the animal by sound and sign, trap or remove it, then seal the entry with metal. The one thing not to do is bait or seal while the animal is still inside the wall.
The scratching noise in your walls at night is most likely mice. Cornell's Integrated Pest Management program lists house mice, white-footed mice and deer mice as the common rodent pests in New York, and the last two spend most of the year outdoors and enter buildings from fall through spring. All of them are nocturnal, which is why the sound starts after you turn the lights off.
What you are hearing is a mouse using the wall void as a highway. Mice nest in walls, under cabinets, and next to anything warm; the Internet Center for Wildlife Damage Management notes they prefer to nest near heat sources like compressors, pilot lights and hot water heaters. From that nest they run the same routes every night to whatever food they have found. Penn State's rodent training material puts their range at just 10 to 30 feet from the nest and notes a mouse nibbles around 30 times a night, so a mouse in a bedroom wall is usually living within that bedroom, the closet behind it, or the bathroom next door.
The sound profile matters. Mice are light, so what comes through drywall is a quick, dry skittering, a scratch of claws on the paper backing, and a faint, rhythmic gnawing where they are opening a hole or working on a wire. It starts and stops. It moves from one spot to another along the same stretch of wall. It is never a thump. If you are hearing weight, keep reading, because that changes the animal and the job.
You tell mice, rats, squirrels and raccoons apart by three things: the time of day, the weight of the sound, and where in the house it is coming from. Nighttime plus light and fast means mice. Nighttime plus heavy and low means rats. Daytime, especially early morning, plus the attic means gray squirrels. Nighttime plus heavy and overhead means a raccoon.
Here is the full breakdown we use on the phone before we even get to the house.
Mice: active after dark, loudest in the first hours after the house goes quiet. Light skittering, scratching, faint gnawing. Heard in walls at any level of the house, often around the kitchen, bathroom plumbing walls, and the basement ceiling. Droppings are 1/8 to 1/4 inch long with pointed ends, per Cornell.
Norway rats: active after dark too, but you hear the weight. Heavier scurrying, occasional thumps, and a louder gnaw. Almost always low, in the basement, crawl space, garage walls, or the first floor, because Norway rats burrow in soil and come in at the foundation. Cornell puts their droppings at 3/4 to 1 inch, blunt ended. If you have a 2 to 4 inch hole near the foundation outside, that is the burrow. Our guide to telling a mouse from a rat on Long Island covers all 7 tells.
Gray squirrels: active in daytime. The New York State Department of Environmental Conservation notes most squirrel species are active during the daytime, and SUNY ESF puts gray squirrel activity in the 2 to 3 hours after dawn and before dusk. So if you are woken at 6:30 in the morning by scrambling and rolling sounds in the attic, and it goes quiet all night, that is a squirrel. They are fast, they run in bursts, and they roll acorns across the attic floor.
Flying squirrels: this is the one that fools people. New York has two flying squirrel species, and DEC describes them as largely nocturnal and most active at night. They are tiny, about two ounces, and they live in groups. So "squirrel sounds in the attic, but only at night" on Long Island is often southern flying squirrels, not grays.
Raccoons: nocturnal, per DEC's nuisance wildlife fact sheet, and heavy. Slow, deliberate walking overhead, dragging, thumps, and in spring a chattering or crying sound from the young. Almost always in the attic or a soffit, not inside a wall void. Our raccoons in the attic guide covers what New York law allows once you know it is a raccoon.
Two others worth ruling out. Bats make a scratching and high chirping at dusk as they leave the roost, and the sound comes from one spot near the eaves rather than traveling. Carpenter ants in a damp wall produce a dry rustling, like crinkling cellophane, that is loudest when the house is quiet and is steady rather than start and stop. Both are different jobs, so if the sound does not fit the four above, say so when you call.
The scratching started in late October because that is when Long Island's first frost pushes rodents indoors. Cornell Cooperative Extension puts the island's average first 32 degree freeze between October 20 and just after November 10 depending on where you live, and the Internet Center for Wildlife Damage Management states mice are most likely to invade structures as temperatures cool in the fall. The noise you are hearing this week is the move-in.
White-footed and deer mice are the main fall arrivals on Long Island's North Shore, in the wooded parts of the Town of Oyster Bay, Huntington, Smithtown and the Pine Barrens, where they spend summer outdoors and then look for a warm cavity when the nights drop into the 30s. House mice are different. They can live their whole life indoors, so in a Levittown ranch or a Massapequa split that has had mice before, the fall noise is often a population that was already there getting more active as the house warms and the outdoor food dries up.
Squirrels follow the same calendar for a different reason. Gray squirrels do not hibernate, and they move into attics in fall and winter for a dry den when their leaf nests fail in the wind. Raccoons start checking attics and chimneys for a winter den in the same stretch. So late October through December is when every one of these animals is testing your house, and the first cold snap is the starting gun.
They are getting into your house through a gap you would never have guessed was big enough. The CDC states a mouse can fit through a hole the width of a pencil, 1/4 inch or 6 millimeters. Cornell's rodent page shows a school door with a 1/2 inch gap gnawed at the bottom, which was enough for rats. Squirrels and raccoons chew or pry their way in at the roofline.
For mice and rats, the CDC's own checklist of where to look outside is the list we work from: the roof among the rafters, gables, eaves and soffits; around windows and doors without weather stripping; between the foundation and the ground; around attic and crawl space vents; and around the holes for electrical, plumbing, cable and gas lines. On a Long Island house the ones that get missed most are the gap where the AC line set enters the siding, the dryer vent flap that no longer closes, the garage door bottom seal, and the sill plate line where old brick or block meets the framing.
Mice also come in high. Cornell's fall pest guidance notes that white-footed and deer mice enter buildings from above, using tree branches that touch the roof and the point where the electrical service wire meets the house. That is why a homeowner can seal the whole foundation and still hear scratching in a second floor wall. The mouse never used the foundation.
For squirrels and raccoons, the entry is at the top: a chewed lattice gable vent, a soffit panel pushed up where it meets the fascia, a rotted corner of the roof return, or an uncapped chimney. You will usually see it from the yard with binoculars, along with claw marks and a greasy rub mark on the siding below it.
If you ignore scratching in the walls, a mouse problem in October becomes a mouse population by January. The Internet Center for Wildlife Damage Management reports a female house mouse can have 5 to 10 litters a year of 5 or 6 young, and the young are sexually mature within 6 to 10 weeks of birth. Two mice in a warm wall in October is dozens by the time you are taking down the holiday lights.
The damage is the second problem. Cornell's rodent page lists what mice and rats gnaw: weather stripping, wood, sheetrock, and electrical wires, and it notes that a percentage of building fires with an unknown cause is thought to come from rodents chewing wires. Squirrels do the same thing in attics with more force, and the Maryland Department of Natural Resources notes they occasionally chew wiring and cause shorts and fires. Raccoons tear insulation and use one corner of the attic as a latrine.
The health piece is the one people underestimate. Cornell notes that components of rodent urine are a known allergen linked to asthma, and that cleaning up dry rodent droppings without a mask is the primary route of exposure for one type of hantavirus. So when the mice are finally gone, the attic or wall void they used still needs to be handled correctly. Do not sweep or vacuum dry droppings. Wet them down with disinfectant first and wear a respirator, or have it done as part of the job.
No. Putting rodent bait inside a wall and sealing the hole is the single mistake that turns a noise problem into a smell problem. A poisoned mouse crawls back to its nest in the wall void to die, and the odor from one dead mouse behind drywall lasts two to three weeks. A dead rat lasts longer. There is no way to get it out without opening the wall.
Bait has a place, and it is outdoors in locked, tamper-resistant stations along the foundation where rats are burrowing, not loose in a wall or attic. Inside the house, where the animals are living in the voids, trapping is the method, because a trapped animal is a removed animal. That is the approach every public health agency recommends and it is how we run every mouse job on Long Island.
Poison is also the wrong tool for everything that is not a mouse or rat. Squirrels, flying squirrels and raccoons are wildlife, and in New York they are handled by trapping and removal under the state's nuisance wildlife rules, not with rodenticide. A poisoned squirrel in a soffit is a worse version of the dead mouse problem.
The sealing mistake is just as common. Homeowners hear scratching, find a hole outside, and stuff it with foam that afternoon. If the animal is inside at that moment, it is now trapped, and a trapped mouse, squirrel or raccoon chews or claws a new exit. Sometimes that exit is into your bedroom. Seal only after two or three nights of total silence following trapping, and never with foam alone, because Cornell, the CDC and every extension office agree rodents chew through foam and caulk. Steel wool held in place with caulk for small holes; hardware cloth, lath metal, cement or metal sheeting for the bigger ones. Our chart of what mice and rats can chew through lists the 12 materials that fail and the 6 that hold.
This is the order that ends the noise and keeps it from coming back. Skipping a step is why people hear the scratching again every October.
For the full version of the mouse process we use, read how exterminators get rid of mice, the 5-step process we use on Long Island.
A mouse or rat job on Long Island takes 2 to 4 weeks from the first visit to a quiet house, and a squirrel or raccoon job takes 1 to 2 weeks, because the animal has to be trapped on its own schedule before the entry can be closed. The noise usually drops sharply within the first 3 nights of trapping.
What sets the price is the animal, the house, and the access. A mouse job in a Rockville Centre apartment is a different scope from a mouse job in a 3,000 square foot Dix Hills colonial with a finished basement and a walk-up attic. Rats add outdoor bait stations and burrow work. Squirrels and raccoons add the trapping visits, the removal, and the metal sealing of the roofline entry, and a second entry doubles that. Every Bobby Bugs job is quoted in writing before any work begins, and we tell you on the phone what the inspection will cover before we come out. Prices on Long Island vary enough by house that we do not print a number on this page; we will give you one in writing after we have seen the problem.
One hard truth to close on. The homeowners who call us in October spend less than the ones who call in February, because the February house has 3 months of breeding, chewed insulation, and a wall that now needs to be opened. If you are hearing it tonight, the cheapest version of this job is the one you book this week.
You hear scratching only at night because mice, rats and raccoons are nocturnal, and the house is quiet enough after dark for the sound to carry through drywall. If the noise is in the attic in the early morning and stops at night, that is a gray squirrel, which is active in daytime.
A mouse in the wall sounds light and fast: quick skittering, scratching, and a faint gnawing that starts and stops. A rat is heavier and louder, with thumps and a deeper gnaw, and it is almost always low in the house near the basement or foundation. Cornell puts mouse droppings at 1/8 to 1/4 inch and Norway rat droppings at 3/4 to 1 inch.
Yes, for a while. Mice living in a wall void or attic can go weeks without entering a living space if there is food within 10 to 30 feet of the nest, like birdseed in the garage or pet food in the basement. They are still chewing, breeding and leaving droppings in the void, and they move into the kitchen as soon as that food runs out.
No. Mice do not leave a warm wall in winter, and a female house mouse can produce 5 to 10 litters a year, so the noise gets worse, not better. Squirrels and raccoons may leave an attic in spring and return the next fall through the same hole. The only thing that ends it is removing the animals and sealing the entry with metal.
No. Sealing an entry while you still hear activity traps the animal inside, and a trapped mouse, squirrel or raccoon chews a new exit, sometimes into the living space. Trap first, wait for two or three silent nights, then seal with steel wool and caulk or hardware cloth, never foam alone.
It can be. Cornell notes rodents gnaw electrical wires and that some building fires of unknown cause are thought to come from that, rodent urine is a known asthma allergen, and cleaning dry droppings without a mask is the primary exposure route for one type of hantavirus. Raccoons add a rabies and roundworm risk in the attic.
Yes. Bats make scratching and high chirping at dusk from one spot near the eaves as they leave the roost, and the sound does not travel along the wall. Carpenter ants in damp wood make a steady dry rustling like crinkling cellophane. Both are different jobs from rodents, so describe the sound when you call.
Related reading
Sources: CDC, How to Seal Up to Prevent Rodents; Cornell Integrated Pest Management, Mouse and Rat Biology and Behavior; Cornell Integrated Pest Management, Mice and Rats (damage, pathogens, allergens); Cornell Integrated Pest Management, Fall Pests; Internet Center for Wildlife Damage Management, House Mouse Biology; Penn State Entomology, Got Rodents? (PA IPM Program); New York State Department of Environmental Conservation, The Squirrels of New York (Conservationist reprint); New York State Department of Environmental Conservation, Nuisance Wildlife Fact Sheet (raccoons); SUNY College of Environmental Science and Forestry, Gray Squirrel; Maryland Department of Natural Resources, Living With Squirrels; Cornell Cooperative Extension of Suffolk County, Using Average Freeze Dates.
Hearing it tonight? Call (516) 509-6001 and we'll tell you what it is.
Describe the sound and the time of day and we will tell you on the phone whether it is mice, rats, squirrels or a raccoon, then come out and confirm it. Open 7 days a week, 7:00 a.m. to 10:00 p.m., serving Nassau, Suffolk, Queens and The Bronx. Every job is quoted in writing before any work begins.
This article is general pest information for Long Island homeowners, not a diagnosis of your specific situation. Pest behavior varies by home, season, and species, and every job is quoted in writing before any work begins. Pesticide applications are performed by licensed New York State applicators in accordance with label requirements.