Drywood termite damage is often invisible until it becomes serious. These termites live entirely inside the wood they eat, never touching soil or building the mud tubes that make subterranean termites easier to spot. A colony can quietly hollow out structural timbers, furniture, or trim for years before you notice anything wrong. The average homeowner who discovers termite damage spends around $3,000 on repairs, though costs range from minor to catastrophic depending on how long the infestation has gone undetected.
How Drywood Termites Damage Wood
Drywood termites eat across the wood grain, consuming both the softer springwood and the harder summerwood. This creates smooth, sculptured galleries inside the timber that can be surprisingly large while leaving the outer surface intact. Subterranean termites, by comparison, eat along the grain and leave mud or soil in their tunnels. The cross-grain feeding pattern of drywood termites makes their damage structurally significant even in small areas, because they don’t leave the harder wood layers as a skeleton of support.
Because colonies develop slowly, the damage accumulates gradually. After two years, a colony may have fewer than 50 workers (the caste that actually eats wood) and just one soldier. A mature colony typically contains only a few hundred to a few thousand members, far smaller than subterranean colonies that can number in the hundreds of thousands. This means drywood termites won’t eat through a house in a single season. But it also means the damage they cause is subtle enough to go unnoticed for years, compounding over time.
Signs of Drywood Termite Damage
The most reliable indicator is fecal pellets, called frass. Drywood termites push their waste out of tiny “kick-out holes” in the wood surface, and the pellets accumulate in small piles below the infested area. These pellets are distinctive: about 1/32 of an inch long, six-sided, blunt at one end and pointed at the other, with long grooves running down each surface. Even a basic magnifying glass makes these features visible. The pellets generally match the color of the wood being consumed, so they can be tan, brown, or reddish depending on the timber.
The kick-out holes themselves are another clue. They measure roughly 1/16 of an inch in diameter, small enough to miss during a casual inspection but visible if you know what to look for. You’ll most often find them on fascia boards, eaves, and trim. Other signs include:
- Surface blistering or warping on wood that looks otherwise intact, caused by galleries just beneath the surface
- Depressions in roofing or shingles that indicate weakened or collapsed wood underneath
- Shed wings near windowsills, light fixtures, or other entry points, left behind after reproductive termites swarm and pair off
- Hollow-sounding wood when tapped, despite no visible exterior damage
One frustrating characteristic of drywood termite damage is how well hidden it stays. The outer shell of the wood often looks perfectly normal. You might not realize anything is wrong until a piece of trim crumbles during a renovation, or a pile of tiny pellets appears on a windowsill that you keep sweeping away.
Where Damage Typically Occurs
Drywood termites enter homes from above, which sets them apart from subterranean species that come up through the foundation. Their most common entry points are small openings near eaves and rooflines, attic vents, and cracks or gaps around doors and windows. This means attics, roof rafters, and the structural framing near your roofline face the highest risk.
From there, infestations can spread to door frames, window frames, hardwood flooring, exposed beams, and even wooden furniture. Because drywood termites don’t need moisture from the soil, they’re perfectly comfortable in dry upper-story wood that subterranean termites would never reach. Antique furniture and picture frames brought into a home can also carry colonies, introducing an infestation that has nothing to do with your home’s construction or location.
How Much Damage Can They Really Do?
U.S. residents spend an estimated $5 billion annually on termite control and damage repair combined. While subterranean termites account for the majority of that figure, drywood termites are responsible for significant structural losses, particularly in southern and coastal states where they’re most common.
The financial impact varies enormously. Some homeowners discover a small, contained infestation in a single piece of trim and choose not to repair it after the colony is eliminated. Others find that rafters, joists, or wall framing have been hollowed out over a decade or more, requiring thousands of dollars in structural work. In rare cases, homes have been demolished because the damage was too extensive to repair economically. The slow growth of drywood termite colonies is both good news and bad: it means you have time before damage becomes severe, but it also means infestations are easy to ignore until they’re not.
Treatment Options for Active Infestations
Treatment depends on how widespread the infestation is. For localized damage limited to one or two areas, spot treatments can be effective. These include injecting insecticide directly into the galleries through drill holes, or using localized heat treatment to raise the wood temperature high enough to kill the colony. Spot treatments are less disruptive and less expensive, but they require confidence that the infestation hasn’t spread beyond what’s visible.
For widespread or hard-to-locate infestations, whole-structure fumigation (tenting) is the standard approach. The house is sealed under a large tent and filled with a gas that penetrates all wood surfaces, reaching colonies hidden inside walls, attics, and other inaccessible areas. Fumigation requires you to vacate the home for two to three days and remove food, medications, and pets. It’s more expensive and inconvenient than spot treatment, but it’s the only method that reliably reaches every colony in a structure when the full extent of damage is unknown.
Professional inspection is essential before choosing a treatment path. Inspectors look for feeding damage, fecal pellets, kick-out holes, and shed wings to map the scope of the problem. Because drywood termites can infest multiple, unconnected areas of a home simultaneously, what looks like a small problem in the attic may also involve framing behind walls or subflooring in another room entirely.
Preventing Reinfestation
After treatment, the priority is sealing the entry points that allowed termites in. Screen attic vents with fine mesh, caulk gaps around window and door frames, and repair cracks in eaves and fascia boards. Any exposed, untreated wood on the exterior of your home is a potential landing site for swarming termites looking to start new colonies.
Applying a protective finish or paint to bare wood surfaces helps, since drywood termites prefer to enter unfinished wood. Regular inspections of attic spaces, roof framing, and exterior trim, especially in spring and fall when swarms are most common, can catch new infestations early. Checking for those telltale piles of six-sided pellets takes only a few minutes and is the single most effective early warning system you have.