The most common signs of a squirrel in your house are scratching or scampering sounds in the attic, small droppings along beams or in corners, and visible chew marks on wood, soffits, or roofline edges. Most people notice the sounds first, especially early in the morning, but the physical evidence is what confirms it. Here’s how to identify each sign and figure out what you’re dealing with.
Sounds and When You Hear Them
The type of squirrel in your home determines when the noise starts. Gray squirrels are active during the day, so you’ll typically hear them early in the morning as they leave to forage and again in the late afternoon when they return. The sounds are distinctive: loud thumping, scratching, and scurrying that some describe as having “construction demo energy.” It’s heavier and more deliberate than what mice produce.
Flying squirrels are a different story. They’re nocturnal, smaller, and surprisingly social, often living in groups. You’ll hear lighter, quicker scurrying overhead at night. Because they’re active while you’re sleeping, a colony of flying squirrels can live in your attic for weeks before you realize something is wrong. If the noises happen exclusively after dark, flying squirrels are the more likely culprit.
Both species may also produce rolling or tapping sounds. Squirrels cache nuts and acorns, and you might hear them rolling across the attic floor or dropping from a rafter onto insulation.
Droppings: What They Look Like
Squirrel droppings are about 3/8 inch long and 1/8 inch wide, shaped like a coffee bean or raisin with rounded edges and sometimes a bulging middle. Fresh ones are dark brown. Older droppings dry out and shift to reddish, tan, or even greenish tones depending on what the squirrel has been eating. Because squirrels consume a lot of vegetation, their droppings show more color variation than rat or mouse waste.
Knowing the difference matters. Rat droppings are larger (1/2 to 3/4 inch), darker, and more uniform in shape. They also tend to appear in tight clusters. Mouse droppings are much smaller, about 1/4 inch, thin, and pointed at both ends. Squirrel droppings are rounder than both and typically show up in piles of fewer than a dozen pellets along beams, in attic corners, or tucked near entry points like roof edges and soffits. Finding multiple piles in the same spot is a strong indicator that a squirrel is returning regularly rather than just passing through.
Chew Marks and Structural Damage
Squirrels are rodents, and their teeth never stop growing. They chew constantly to keep them filed down, and they’re not selective about materials. Wood, plastic, and the protective insulation around electrical wiring are all fair game. In an attic, look for gnaw marks on rafters, joists, and any exposed wiring. Chewed wood typically shows fresh, lighter-colored gouges compared to the surrounding aged surface.
Gray squirrels cause the most obvious structural damage. They tear and chew aggressively, and you may find shredded insulation pulled apart for nesting material. Flying squirrels do less dramatic chewing but create a slow buildup of nesting debris and contamination over time, especially when living in groups.
The fire risk from chewed wiring is real. Damaged wires can cause shorts, power outages, or fires. Rodents are estimated to be responsible for 20 to 25 percent of all house fires of unknown cause, according to the National Fire Protection Association, largely because of their habit of gnawing through electrical wiring and gas lines. If you find any exposed or frayed wires in your attic, treat it as urgent.
Entry Holes and Where to Find Them
Squirrels need a gap of only 1.5 inches to squeeze into your roof. If the gap isn’t quite big enough, they’ll gnaw it wider. The most common entry points are along fascia boards, soffits, soffit vents, ridge vents, and gable vents. The roof return, where the exterior wall meets the roof under the eaves, is one of the most accessible spots because squirrels can easily climb onto the roof and find loose or deteriorating material there.
To check for entry holes, walk the perimeter of your home and look up along the roofline. Chewed or splintered edges on wood trim, displaced vent covers, and gaps where fascia meets the soffit are the places to focus on. Inside the attic, daylight visible through the roof or walls during the day pinpoints exactly where an opening exists. You may also notice droppings concentrated near these holes since squirrels pass through them repeatedly.
Smell and Staining
A single squirrel may not produce a noticeable odor, but a family or a group of flying squirrels will. Urine soaks into insulation and wood over time, leaving yellow or brown stains on ceilings or attic surfaces. The smell is musky and persistent, and it intensifies in warm weather. If you notice a new, unexplained stain on a ceiling below the attic, especially one that seems to be getting larger, squirrel urine saturation in the insulation above is a common cause.
Nesting Material and Debris
Squirrels build nests from whatever is available indoors. Shredded insulation is the most common material, but they’ll also gather leaves, bark, fabric, and cardboard. These nests are typically tucked into corners of the attic, between wall studs, or in gaps around ductwork. You may also find stashes of acorns, walnuts, or other food cached nearby, particularly in garages and sheds that serve as secondary storage sites.
Peak Seasons for Squirrel Infestations
Squirrels give birth twice a year, and the nesting instinct is the primary reason they break into attics. The first wave happens in late winter and early spring, with babies arriving in March and April. The second comes in late summer through early fall, typically late August into September. These are the months when you’re most likely to hear new activity overhead.
Timing matters if you’re planning to seal entry points. If you block a hole during breeding season, you risk trapping baby squirrels inside, which creates a worse problem. The mother will chew aggressively to get back in, and young squirrels that can’t escape will die in the walls or attic. Any exclusion work should account for whether juveniles might still be in the nest.
Getting Squirrels Out Safely
The standard approach for most wildlife is a one-way exclusion door: a device that lets the animal leave but not re-enter. For squirrels, this method carries more risk than with other species. Because squirrels chew so aggressively, they’ll often gnaw a new hole right next to the one-way door or find another weak spot in the structure. Wildlife professionals generally reserve one-way doors for squirrels only when the exterior is brick, block, or metal, materials that resist chewing.
The critical rule for any exclusion method is that every other potential entry point must be sealed before the one-way door is installed. If even one gap remains, the squirrel will find it immediately. Once sealed out, most squirrels give up and relocate within one to three days. Professionals typically remove the one-way device a few days after that and complete the final seal.
For gray squirrels in particular, a wildlife removal professional can assess whether young are present before any exclusion begins. This is especially important during the late summer breeding season, when a second litter may still be in the attic. Sealing adults out while juveniles remain inside is the single most common mistake homeowners make when trying to handle a squirrel problem on their own.