Home Exterior Clues
Signs on siding, foundations, decks, and eaves
Clues on the house itself deserve faster attention than clues in the yard, because the stakes are different: a hole in the lawn is cosmetic, but a mud tube on the foundation or a row of holes in your siding can mean active damage to the structure. The encouraging part is that these signs are distinctive and easy to check. These guides show you how to identify the most common exterior warning signs, which ones are urgent, and what a professional will look for when you call.
Home Exterior Clues guides
Mud Tubes Near Your Foundation: The Termite Warning Sign Pencil-width mud tunnels running up your foundation wall are most likely shelter tubes built by subterranean termites — the single most important early warning sign of an active infestation. Mud dauber wasp nests and rain-splashed soil can look similar at a glance, but termite tubes follow continuous vertical paths from soil to wood. Of every clue on this site, this is the one that should never wait: schedule a licensed termite inspection promptly. Read the guide → Scratching Noises in Walls at Night: What's Living in There? Scratching in your walls at night most often means mice or rats, since both are nocturnal — light, fast scratching suggests mice, while heavier gnawing and movement suggests rats. If the noise happens in daylight, especially at dawn and dusk, squirrels are the likelier tenant. The time of day, the weight of the sound, and where in the house it comes from will narrow it down before you ever see the animal. Read the guide → Skunk Smell Around Your House at Night: What It Means A skunk smell around your house at night usually means a skunk sprayed nearby — most often in late winter mating season, when males roam and spray more — or that one is denning under your deck, porch, shed, or crawl space. If the smell is inside, it was likely pulled in through vents, a crawl space, or a sprayed pet. If a rotten-egg or skunky odor is indoors, persistent, and strongest near a gas appliance or meter, treat it as a possible gas leak and leave the house. Read the guide → So Many Ladybugs on Your House? Why They Swarm in Fall If you suddenly have hundreds of ladybugs on your siding or inside around the windows, they're almost always multicolored Asian lady beetles moving in for the winter. On warm, sunny afternoons in October and November they swarm to sunny, light-colored walls and crawl into cracks to overwinter in walls and attics. They don't breed indoors or damage the house; vacuum them up gently, seal the gaps they use, and leave the ones outdoors alone, since they eat aphids. Read the guide → Squirrels in the Attic? Signs, Noises, and How to Get Them Out Scurrying, scratching, or rolling sounds in the attic at dawn and again in late afternoon most likely mean gray squirrels, which chew in at roof edges, soffits, and vents. Noise at night points instead to flying squirrels, raccoons, mice, or rats. The humane fix that works is sealing every secondary gap, putting a one-way exclusion door on the main entry, and sealing it permanently once the animals are gone — timed so no babies are left inside. Read the guide → Stink Bugs on Your House in Fall: Why They're Here and What to Do Shield-shaped brown bugs crowding your siding, window frames, and doors in late September and October are most likely brown marmorated stink bugs looking for a warm place to spend the winter. They don't bite, aren't poisonous to people, and don't damage the house, but they do stink when crushed or disturbed. The fix is to seal the gaps they use to get inside, and to vacuum or drop any indoor bugs into soapy water rather than squashing them. Read the guide → Black Streaks on Your Roof: Algae, Moss, or Something Worse? Black streaks running down your asphalt shingles are almost always a blue-green algae called Gloeocapsa magma — a cosmetic problem, not mold and not roof failure. The streaks show up first on north-facing and shaded slopes where moisture lingers, and they darken as the algae colony spreads year after year. Moss, lichen, and chimney soot can look similar, but each behaves differently and only moss actually threatens the shingles. Read the guide → Chewed Wires and Screens: Rodent Damage and Fire Risk Chewed wires, cables, and window screens are almost always rodent work — mice, rats, or squirrels, whose front teeth grow continuously and must be worn down by gnawing. The size of the tooth marks and where the damage sits tells you which rodent, and chewed electrical wiring in particular is urgent: exposed conductors inside walls are a genuine fire hazard that needs both an electrician and a pest professional. Read the guide → Does Salt Damage Concrete? Why Your Driveway Is Flaking Yes — salt can damage concrete, but mostly indirectly. Ordinary rock salt doesn't chemically eat sound concrete much; instead, the salty meltwater soaks into the surface, refreezes, and expands, popping off thin layers in a process called scaling. New concrete, concrete poured without air entrainment, and slabs with a weak, overworked top layer are the most likely to flake, pit, or crumble after a salty winter. Read the guide → Greasy Rub Marks Along Walls: The Sign of a Rodent Runway Dark, greasy smudges running in a line along your baseboards, foundation, pipes, or rafters are most likely rub marks — oil and dirt from rodent fur deposited as the animal follows the same route night after night. Prominent, continuous marks usually mean rats; smaller, fainter smudges mean mice. Because rub marks only build up through repeated travel, finding them means a runway is established, not that an animal passed through once. Read the guide → Round Holes in Wood With Sawdust: Bees, Ants, or Beetles? A perfectly round hole about 1/2 inch across with a pile of coarse sawdust beneath it is the signature of carpenter bees, especially on bare or weathered wood. Fine sawdust-like debris coming from cracks and seams rather than a drilled hole points to carpenter ants, while clusters of much smaller holes are usually old wood-boring beetle exits. The hole's size, the texture of the sawdust, and whether you see insect traffic will tell you which one you have. Read the guide → Wasp Nest Under the Eaves: Which Wasp, and How Careful to Be A nest under your eaves is most likely paper wasps if you can see open honeycomb cells on an umbrella-shaped comb, bald-faced hornets if it's a fully enclosed gray papery ball, or mud daubers if it's made of dried mud tubes. Paper wasps and hornets will defend their nest, while mud daubers almost never sting. Identify the builder from a distance first — the right response ranges from leaving it alone to calling a licensed pest control professional. Read the guide → Woodpecker Holes in Siding: Why They Drill and How to Stop It Holes pecked in your siding usually mean a woodpecker is foraging for insects, drumming to claim territory, or excavating a nest cavity — and rows of small holes often signal that insects like carpenter bee larvae are already living in the wood. A single clean half-inch round hole with sawdust below it, on the other hand, is typically the work of carpenter bees themselves. Because woodpeckers are federally protected, the fix is deterrence and repair, never harm. Read the guide →
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