Drywood and subterranean termites differ in where they live, how they damage your home, and what it takes to get rid of them. Subterranean termites nest underground and build mud tubes to reach wood, while drywood termites live entirely inside the wood they eat, needing no soil contact at all. This distinction drives nearly every practical difference between the two, from the warning signs you’ll spot to the treatment options available.
Together, termites cause roughly $5 billion in control and repair costs for U.S. homeowners each year, damaging about 600,000 homes. The average repair bill after a termite discovery runs around $3,000. Knowing which type you’re dealing with matters because the treatments for one won’t work on the other.
Where Each Type Lives
Subterranean termites build their colonies in the soil. They need consistent moisture to survive and are vulnerable to drying out, so they construct mud tubes (sometimes called galleries) from a mixture of soil, saliva, and feces to travel between their underground nest and the wood they’re feeding on. These tubes act like climate-controlled highways, locking in humidity and shielding the colony from predators and open air. Working tubes can transport hundreds to thousands of termites daily, and exploratory tubes can extend up to 15 feet above ground level when built over concrete or metal surfaces.
Drywood termites skip the soil entirely. A mated pair bores directly into a piece of wood, seals the entrance, and raises the colony inside the timber itself. They extract all the moisture they need from the wood they consume, which means they can infest any wooden structure regardless of ground contact: roof framing, window frames, furniture, even picture frames. Because they don’t need to return to the ground, there are no mud tubes to find.
Colony Size and Speed of Damage
Subterranean colonies are dramatically larger. A mature colony can contain hundreds of thousands of individuals, and some species reach into the millions. Even so, growth is slow at first. After a year, a new colony may have only about 75 members. Once established, subterranean termites consume wood at rates that increase with temperature, peaking during hot summer months. Even a small amount of rain during June through September pushes more foragers above the soil surface and accelerates feeding. They also prefer decayed wood over sound wood, because fungi in rotting timber pre-digest cellulose into smaller molecules the termites process more easily.
Drywood termite colonies are much smaller, typically numbering in the low thousands at maturity. Their damage accumulates more slowly as a result, but that doesn’t make them harmless. Because they live hidden inside wood and produce subtle signs, infestations often go undetected for years, allowing significant structural weakening before anyone notices.
How to Tell Them Apart Visually
If you catch a swarm, wing shape is the most reliable way to distinguish the two. Drywood swarmer wings have three heavy veins along the front edge and angled crossveins near the tip that form trapezoidal cells. Subterranean swarmer wings have just two major veins along the front edge with perpendicular crossveins, creating square or rectangular cells. You’ll need a magnifying glass or a good phone camera to see this clearly, but it’s a definitive difference.
Body size also helps. Drywood swarmers are about 7/16 inch long and range from light yellow to black with clear or smoky gray wings. Subterranean swarmers are slightly smaller, about 1/4 to 3/8 inch, with pale yellow-brown to black bodies and smoky gray to brown wings. Soldiers of both species have enlarged heads with strong mandibles, but drywood soldiers have distinctly large, rectangular, darker heads compared to the more rounded brownish heads of subterranean soldiers.
Signs of Infestation
The telltale sign of subterranean termites is mud tubes running along foundation walls, piers, or plumbing penetrations. These pencil-width tunnels are made of dirt and are easy to spot on concrete, brick, or exposed wood. You may also notice swarm castles, which are large temporary mud structures (sometimes four feet wide or more) built to accommodate swarmers leaving the colony. Drop tubes, which look like stalactites hanging from wood down toward the ground, are another giveaway.
Drywood termites leave a completely different calling card: tiny fecal pellets. Because they live inside the wood, they cut small “kickout holes” to push waste out. Under magnification, the pellets have a distinctive six-sided, oblong shape and are fairly uniform in size, though color varies with the type of wood. To the naked eye, they look like fine dust or sand. If the kickout hole is close to a surface, the pellets form a small, neat pile. If it’s higher up, the pellets bounce and scatter, making them easy to mistake for ordinary debris. These pellet piles are often the only visible evidence of a drywood infestation, so they’re worth learning to recognize.
Treatment Approaches
Treatment methods differ sharply because the two species live in fundamentally different places. Getting this identification right is critical. Treatments designed for subterranean termites will not control drywood termites, and vice versa.
Subterranean Termite Treatment
Most subterranean control involves creating a chemical barrier between the soil colony and the wood it’s targeting. A licensed applicator injects termiticide into the ground around and beneath the structure, forming a continuous treated zone the termites can’t cross without exposure. The alternative is a bait station system installed in the soil around the home’s perimeter. Bait stations don’t leave chemical residue in the soil but work by attracting foraging termites to a slow-acting toxin they carry back to the colony. Over time, baits can reduce or eliminate an entire colony.
Drywood Termite Treatment
Drywood treatment falls into two categories: whole-structure and localized. If the infestation is widespread or you can’t pinpoint every colony, whole-structure fumigation is the standard. The home is tented and filled with sulfuryl fluoride, an odorless, colorless gas that penetrates all wood in the structure. The gas is held inside for roughly 16 to 30 hours, then the building is aerated with fans for at least 12 hours. You can’t re-enter until gas levels drop to one part per million or less. Fumigation is highly effective when done correctly and is the only option that reaches hidden colonies you can’t see or access.
If the infestation is limited to a small area, localized treatments can work. Heat treatment involves raising wood temperature to at least 120°F and holding it there for a minimum of 33 minutes, which kills termites without chemicals. Microwave devices destroy termites by boiling fluids inside their cells. High-voltage electrocution devices (90,000 volts at very low current) are another nonchemical option. Liquid or dust insecticides can also be injected into infested wood. The catch with all localized methods is that they only work if you’ve accurately identified every infested area, which is difficult with termites that live invisibly inside wood.
Prevention for Each Type
Preventing subterranean termites centers on breaking the soil-to-wood connection. Keep soil graded away from your foundation, eliminate wood-to-ground contact (including fence posts, deck supports, and form boards left in place after construction), and fix any moisture problems like leaky pipes or poor drainage. Subterranean termites are drawn to wet, decaying wood first, so reducing moisture around your home’s perimeter makes it a less attractive target. Pre-construction soil treatments provide long-lasting chemical barriers for new builds.
Drywood termite prevention is trickier because they fly in and bore directly into exposed wood. Sealing cracks and gaps around eaves, vents, and window frames helps reduce entry points. Screening attic and crawlspace vents with fine mesh (20-gauge or smaller) blocks swarmers from accessing interior framing. Applying wood treatments or coatings to exposed timber, especially in attics and exterior trim, creates a surface drywood termites are less likely to penetrate. Because drywood colonies grow slowly, regular inspections that catch infestations early, before they spread through multiple structural members, give you the widest range of affordable treatment options.
Geographic Distribution
Subterranean termites are found throughout most of the continental United States, with activity increasing as you move south and east into warmer, more humid climates. They’re the most common and most economically damaging termite group nationwide. Formosan subterranean termites, a particularly aggressive species, account for at least $1 billion in annual control and repair costs on their own, with some estimates closer to $2 billion.
Drywood termites are more geographically limited, concentrated along coastal areas of the southern United States, from California through Texas and across the Gulf Coast to Florida. In Mississippi, for example, drywood infestations account for less than 1% of all termite cases reported. But within their range, especially in Southern California and coastal Florida, they’re a serious and common problem. They can also be transported long distances inside infested furniture or lumber, occasionally turning up well outside their usual territory.