Most Hill Country homeowners hear 'termites' and picture the ones in the soil, the kind that build mud tubes along your foundation. Those are subterranean termites, and yes, they're here. But drywood termites are also common in the area, and they work completely differently. They don't need soil contact, don't build mud tubes, and can live inside bone-dry wood: attic framing, hardwood floors, furniture. Treating for one when you have the other is wasted money and time.
Dealing with this right now?
Knowing whether you have drywood or subterranean termites, or both, is the foundation of an effective treatment plan. Contact ACI Pest for a thorough inspection that tells the species apart and recommends the right approach for your Hill Country home.
See how we handle it on our termites page.
The Fundamental Difference: Moisture Requirements
The key difference comes down to moisture. Subterranean termites must keep contact with soil or a persistent moisture source to survive. That's why they build mud tubes along your foundation walls. They can't tolerate drying out while exposed to air. That soil dependence is also their weakness, because an effective soil treatment creates a chemical barrier they can't cross. It also means they go after moisture-compromised wood and work their access points from the ground up.
Drywood termites (primarily Incisitermes species in Texas) are built to pull all the moisture they need straight from the wood itself. They don't need soil contact, don't build mud tubes, and can set up colonies inside dry, sound wood that has never seen a drop of water: furniture, picture frames, hardwood floors, attic framing. That independence from soil is exactly what makes them hard to treat with conventional subterranean termite methods.
Identifying Drywood Termites in the Hill Country
The clearest sign of drywood activity is frass. Tiny, six-sided pellets. They look like coarse coffee grounds or sawdust, and under magnification you can pick out the distinctive hex shape. Drywood termites push this frass out of kick-out holes in the wood, so small piles below furniture, window sills, attic framing, or hardwood floors give them away. Color runs from pale cream to dark brown, depending on what wood they're eating.
In Texas, drywood termites swarm in fall, usually after the first rains following a dry summer. That lines up with the late-September and October weather here. The swarmers (winged reproductives) are reddish-brown, roughly 3/8 inch long including wings, and they drop those wings once they land. Find shed wings near window sills or light fixtures in fall and you've likely got an active colony.
- Frass (hex-shaped pellets) below furniture, window frames, or attic flooring
- Tiny kick-out holes in wood surfaces, often plugged with frass
- Swarming winged reproductives or shed wings in fall, often near light sources
- Hollow-sounding wood when tapped, but no mud tubes
- Damage pattern runs across wood grain and through both hard and soft growth rings
Identifying Subterranean Termites in the Hill Country
Subterranean termites give themselves away with mud tubes. These are pencil-width tunnels of soil, saliva, and debris the colony builds to shield itself while traveling between soil and food sources. The tubes show up most on foundation walls, along the inside of pier-and-beam crawl spaces, and on the exterior of concrete block foundations. Break a tube open and come back the next day. If it's been repaired, the infestation is active.
Subterranean termite damage follows the soft spring growth rings in wood and skips the harder summer rings, leaving a layered, honeycomb look. The chambers are usually packed with mud and fecal material. Unlike clean drywood galleries, subterranean galleries are rarely smooth. Formosan subterranean termites are an invasive species pushing its range into Central Texas, and they build especially aggressive colonies plus a distinctive carton material (hardened frass and soil) rather than mud in their tubes and chambers.
Treatment: Why the Species Determines the Method
Subterranean termites are treated with soil-applied liquid termiticides or baiting systems. Liquid treatments lay down a continuous chemical barrier in the soil around and beneath the structure that kills termites on contact or transfer. Bait stations turn the colony's social behavior against it. Workers collect bait and share it with the queen and reproductives, and the colony eventually collapses. Both methods need access to the soil around the structure's perimeter, which is why neither does anything to drywood termites living in above-ground wood.
Drywood termites are treated by localized wood treatment (injecting insecticide directly into galleries through the kick-out holes), whole-structure fumigation with sulfuryl fluoride, or heat treatment. Fumigation remains the only method proven to reach all colonies throughout a structure when the infestation is widespread or in inaccessible locations. Localized treatment is appropriate when the infestation is confirmed to a single, accessible area. Neither approach involves soil application.
Which Species Is More Common in the Hill Country?
Subterranean termites are more common in Texas overall and cause greater aggregate economic damage. However, the Hill Country's hot, dry climate and the elevated presence of aged cedar and hardwood structures make drywood termite activity notably more common here than in wetter parts of the state. Historic Hill Country homes with original cedar lumber framing, tongue-and-groove pine flooring, and minimal humidity control in attics are particularly vulnerable to drywood termite establishment.
It's also possible, and not rare, to find both species in a single structure. A home with subterranean termite activity in the foundation sill plates and a drywood termite colony in the attic framing needs a combined treatment program. That's one reason a thorough inspection by a licensed professional, rather than a quick look of your own, is essential before you commit to a treatment approach.
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