Termites don’t actually bite wood the way you might picture it. They chew through it using saw-toothed mandibles, scraping away tiny pieces of wood fiber and digesting the cellulose inside. The result is distinctive damage patterns that look nothing like the marks left by other wood-destroying insects. Knowing what termite damage looks like, and how it differs from other pests, can help you catch an infestation before it compromises your home’s structure.
How Termites Actually Eat Wood
Worker termites are the ones doing the chewing. They use hardened mouthparts to scrape wood fibers loose, then swallow the material and break it down internally. What makes termites unique among wood-destroying insects is that they can actually digest cellulose, the tough structural compound that makes up wood. Most animals can’t do this.
Termites pull it off thanks to a dense population of bacteria and protozoa living in their gut. Their hindgut works like a fermentation chamber, where these microbes convert cellulose into short-chain fatty acids the termite absorbs for energy. Termites also produce their own digestive enzymes in their salivary glands, which work alongside the microbial enzymes to maximize how much nutrition they extract from every bite. The colony even recycles nutrients by feeding on each other’s waste and exchanging gut microbes mouth-to-mouth, ensuring that every member, including soldiers and juveniles who don’t forage, maintains the right gut biology to process wood.
What Termite Damage Looks Like
The appearance of termite damage depends on which species is doing the eating. The two most common culprits in homes are subterranean termites and drywood termites, and they leave distinctly different marks.
Subterranean Termite Damage
Subterranean termites typically eat only the softer springwood in a piece of lumber, leaving the harder summerwood layers intact. This creates a thin, layered appearance, almost like the pages of a book, with alternating strips of damaged and undamaged wood. You’ll often find soil packed inside the galleries because these termites bring mud with them from their underground colonies. The most recognizable early sign is mud tubes, pencil-width tunnels made of soil and saliva that run along foundation walls, crawlspace piers, or other surfaces between the ground and the wood they’re feeding on.
Drywood Termite Damage
Drywood termites are less selective eaters. They consume both the soft springwood and the harder summerwood, which gives their tunnels a smooth, sculptured appearance rather than the layered look of subterranean damage. Instead of mud, drywood termite galleries contain fecal pellets. These pellets are tiny, about the size of a grain of sand, hard and dry, with six concave sides that give them a hexagonal shape under magnification. Their color ranges from light tan to dark brown depending on the wood being eaten.
Drywood termites push their waste out of small openings called kick-out holes to keep their galleries clean. Finding a small pile of these pellets beneath a wooden surface, sometimes mistaken for sawdust or coffee grounds, is one of the clearest signs of an active drywood infestation.
Termite Damage vs. Other Wood-Destroying Insects
Several insects damage wood, and telling them apart matters because the treatment approach differs for each one.
- Carpenter ants don’t eat wood at all. They excavate it to build nesting galleries, then discard the debris. Their tunnels look holey and cavernous compared to termite damage, and the interior walls appear sanded smooth. You’ll find wood shavings and sometimes discarded wings near entry holes.
- Powderpost beetles bore small round holes between 0.03 and 0.3 inches in diameter, depending on the beetle species. They leave behind fine wooden flakes that look like sawdust or powder, which is how they got their name.
- Termites produce a stripped, striated look inside the wood. The key distinguishing clue is the presence of mud tubes (subterranean) or hexagonal frass pellets (drywood). Termite entry points are often less visible than beetle holes because they frequently enter wood from below or behind, where you can’t easily see.
How to Check for Termite Damage
You can catch some signs of termite activity with a simple visual inspection. Look for mud tubes along your foundation, bubbling or peeling paint on wood surfaces, and tiny piles of frass pellets near baseboards, windowsills, or door frames. Tap on wood that you suspect might be damaged. Termite-hollowed wood produces a distinctly hollow sound compared to solid lumber, and heavily damaged wood may feel soft or give way under light pressure.
Professional inspectors go further with specialized tools. Moisture meters help identify areas with elevated moisture levels, since subterranean termites are drawn to damp wood. Thermal imaging cameras can detect temperature differences behind walls that suggest termite activity. Inspectors also use sounding tools, specialized tappers designed to find hollow spots, and borescopes, small cameras on flexible tubes that can be threaded into walls to see what’s happening behind the surface.
If you’re buying a home, a termite inspection is typically separate from a standard home inspection and worth requesting. Damage can be extensive behind walls and under floors long before any visible signs appear on the surface.
How Much Damage Requires Repair
Not all termite damage is structural. Surface-level feeding on trim, baseboards, or non-load-bearing wood can often be treated with wood hardeners or fillers once the infestation is eliminated. The real concern is when termites reach load-bearing elements like floor joists, support beams, or wall studs.
For damaged joists, the common repair approach is sistering, which means bolting a new piece of lumber alongside the damaged one to restore strength. A typical sister joist extends at least two feet past the damaged area on each side. In cases where the damage is severe or extends unpredictably through the wood, full replacement may be the safer option. Termites can hollow out wood internally while leaving the exterior looking mostly intact, so once you find damage at one end of a joist, you can’t always be sure how far it extends into the middle.
The critical first step before any repair is confirming the termites are gone. Patching damaged wood while an active colony is still feeding is like repainting a wall with a leak behind it. A pest control professional can verify whether the infestation is active and recommend treatment before structural repairs begin.