Termite damage on wood has a few telltale visual signatures depending on the species involved, but the most common signs include hollowed-out galleries running through the wood, mud or soil packed inside tunnels, small piles of pellets beneath tiny holes, and paint or surfaces that appear sunken or blistered. Knowing exactly what to look for helps you distinguish termite damage from other wood-destroying pests and from ordinary wood rot.
What Subterranean Termite Damage Looks Like
Subterranean termites are the most common type in the United States, and their damage has a distinctive muddy quality. Because these termites travel through the ground to reach wood, they bring soil and moisture with them. When you break open damaged wood, you’ll find galleries running along the grain that are lined with dried mud and dirt. If the galleries contain dried mud but no live termites, you may be looking at old damage from a previous infestation.
On the surface, subterranean damage often shows up as narrow, sunken winding lines or trails beneath paint, wallpaper, or drywall. The wood may look blistered or water-damaged from the outside while being extensively hollowed inside. Sheetrock walls sometimes develop sunken tracks where termites have been feeding on the cardboard layer beneath the paint.
The most recognizable exterior sign is mud tubes: pencil-width tunnels built from soil, wood particles, and debris that run from the ground up to the wood the termites are eating. You’ll find these on foundation walls, floor joists, hanging from sub-flooring, or tucked into cracks between structural members. Tubes found along ceilings or upper floors suggest the colony actually lives inside the building rather than underground.
What Drywood Termite Damage Looks Like
Drywood termites don’t need contact with soil, so their damage looks very different. They eat both the soft and hard layers of wood, creating smooth, sculptured galleries that can run across the grain rather than just along it. There’s no mud lining inside the tunnels. Instead, the galleries contain small fecal pellets.
The clearest visual giveaway is these pellets. Drywood termite frass has a unique shape: each pellet is roughly 1/32 inch long, six-sided, blunt at one end and pointed at the other, with long dimpled grooves running down the surface. Under even modest magnification, this shape is unmistakable. The color ranges from light tan to dark brown depending on the type of wood the termites are eating. Pellets are pushed out of “kick holes,” tiny openings about 1/16 inch in diameter that the termites drill through the wood surface.
If the kick hole is close to a horizontal surface, the pellets form a neat little pile that’s easy to spot. When the hole is higher up, the pellets bounce and scatter on impact, making them easy to mistake for ordinary dust or debris. Tapping gently on suspected wood can dislodge pellets from active kick holes.
Termite Damage vs. Carpenter Ant Damage
Carpenter ants also destroy wood, but their tunnels look noticeably different. Carpenter ant galleries appear smooth and polished inside, almost sanded, and the surrounding wood often looks chipped or scraped. The key difference is cleanliness: carpenter ants don’t eat wood, so they push excavated shavings out of their tunnels. You’ll find piles of coarse wood shavings mixed with parts of dead insects near tunnel entrances.
Termite tunnels, by contrast, contain either packed mud and soil (subterranean species) or six-sided fecal pellets (drywood species). Subterranean termite galleries also tend to look rougher and dirtier than the clean, polished tunnels carpenter ants leave behind. If you break open a damaged piece of wood and find soil tracked into the tunnels, that’s a strong indicator of termites rather than ants.
Termite Damage vs. Powderpost Beetles
Powderpost beetles produce damage that can initially look similar to drywood termites because both leave small holes in the wood surface. The differences become clear on closer inspection. Beetle exit holes are perfectly round, about the size of a pinhead (1/16 to 1/4 inch depending on species), and the frass is a fine powder rather than distinct pellets. Depending on the beetle species, this powder feels like flour or fine talc, sometimes slightly gritty when rubbed between your fingers. It accumulates in small piles beneath the holes or stays tightly packed inside the tunnels.
Drywood termite pellets, by comparison, are clearly individual granules with a visible six-sided shape. If you can see distinct pellets rather than dust, you’re likely looking at termite activity.
Termite Damage vs. Wood Rot
Brown rot, the most common type of fungal wood decay, creates a pattern that’s easy to distinguish from termite damage once you know what to look for. Rotted wood develops fractures both along and across the grain, eventually breaking apart into small cube-shaped pieces. This “cubical” cracking pattern is the hallmark of brown rot. As the rot progresses, the wood becomes brittle, dry, and powdery.
Termite-damaged wood, on the other hand, is hollowed out in galleries or tunnels rather than crumbling into cubes. The internal structure may be extensively eaten away while the outer shell remains intact. Wood rot also won’t contain mud, soil, or fecal pellets inside the damaged areas. That said, termites are attracted to moisture-damaged wood, so it’s possible to find both rot and termite damage in the same piece of timber.
How to Inspect Wood for Hidden Damage
Much of the damage termites cause is invisible from the surface. A flathead screwdriver is the simplest tool for checking suspect wood. Start by tapping along window sills, door frames, baseboards, and any accessible joists or beams with the handle of the screwdriver. Solid, healthy wood produces a sharp, clear sound. Wood that’s been hollowed out by termites returns a dull, hollow thud.
When you find wood that sounds off, or that looks discolored, blistered, or water-damaged, press the screwdriver tip into the surface with firm but moderate pressure. Healthy structural wood resists the probe. Termite-compromised wood gives way far more easily than it should, sometimes caving in completely to reveal galleries underneath. Pay particular attention to areas near the foundation, crawl spaces, and anywhere wood contacts or comes close to soil.