Subterranean termites cause more structural damage in Greater Houston than any other pest, yet most homeowners discover them only after expensive repairs are already needed. The median termite damage claim in Texas exceeds $8,000, and Harris County consistently ranks among the highest-risk counties in the country for termite activity.
Learning to distinguish termite activity from look-alike conditions is the difference between early intervention and a full structural repair. This guide covers every sign of termite infestation specific to Houston homes — and the three conditions that look like termites but are not.
Mud Tubes: The Definitive Sign of Subterranean Termites
Mud tubes (exploratory tunnels built by subterranean termites) are the single most reliable indicator of an active infestation. Workers construct these pencil-thin tunnels from soil, saliva, and wood particles to travel between their underground colony and above-ground food sources — usually wood framing, floor joists, or siding.
Where to check for mud tubes in a Houston home: - Foundation walls — both interior (crawl space, basement) and exterior - Pier-and-beam support posts and crawl space columns - Floor joists and sill plates above the foundation - Wood siding or stucco where it meets the soil - Expansion joints in slab foundations - Utility penetrations where pipes or wires enter the house
In Houston specifically, the high humidity means mud tubes stay moist and pliable for longer. Fresh tubes appear dark brown and feel damp. Dried, crumbled tubes indicate past activity that may or may not be active — only an inspection by a TPCL-licensed technician can confirm current infestation.
Swarmers: Winged Termites That Signal a Mature Colony
Termite swarmers (reproductive alates) emerge from mature colonies to mate and start new colonies. In Houston, subterranean termite swarmers appear February through April, typically after a warm rain when temperatures reach approximately 68°F.
A single swarmer sighting indoors near a window or door indicates a colony somewhere inside the structure — not just outside near the foundation. If you see winged insects emerging indoors, the colony has been established inside the building envelope for 3 to 5 years and has produced hundreds to thousands of reproductive individuals.
Swarmers look similar to flying ants — a common misidentification that delays treatment. Here is the distinction: - Termite swarmers have four equal-sized wings that are twice the body length and shed easily. The body is straight and broad-waisted with straight antennae. - Flying ants have elbowed antennae, a pinched waist, and forewings longer than hind wings. They do not shed wings the same way termites do.
Frass: Termite Droppings That Resemble Sawdust
Drywood termites produce frass — hexagonal pellets of digested wood that accumulate below kick-out holes. In Houston, drywood termites are less common than subterranean species but appear regularly in attic spaces and window frames of older homes.
Frass piles resemble sawdust or coffee grounds but are distinct: termite frass pellets are uniform in size and shape with six distinct concave sides. Sawdust is irregular and includes wood splinters. Carpenter ant debris includes ant body parts and general detritus.
Hollow-Sounding Wood and Blistered Paint
As termites consume wood from the inside out, they leave a thin surface layer of paint, stain, or wood veneer intact. Tapping suspected areas with a screwdriver handle produces a hollow, papery sound instead of a solid thud. Blistered or buckled paint on walls or baseboards often indicates termite activity beneath the surface.
In Houston homes, this sign is particularly common in: - Window and door frames exposed to moisture - Bathroom and laundry room baseboards where humidity is highest - Pier-and-beam subflooring with inadequate ventilation - Attic framing near ridge vents and roof penetrations
Look-Alikes That Are NOT Termites
Not every sign of wood damage means termites. Houston homes commonly show these conditions that mimic termite damage:
Carpenter Ants: These ants excavate smooth, clean galleries in wood for nesting — they do not eat wood. Evidence includes large (up to ½ inch) black or red-black ants, coarse sawdust-like frass mixed with ant body parts, and rustling sounds in walls. Carpenter ants are active at night and are more common in homes with moisture-damaged wood.
Wood Rot: Fungal decay softens wood and causes it to crumble, sometimes resembling termite damage. Wood rot is localized to areas with chronic moisture exposure — leaking pipes, poor gutter drainage, or inadequate crawl space ventilation. Unlike termite galleries that follow the wood grain, rot is amorphous and appears as soft, discolored patches.
Powderpost Beetles: These wood-boring beetles leave exit holes 1/16 to 1/8 inch in diameter and fine, flour-like sawdust. Unlike termites, powderpost beetles attack only seasoned hardwoods — flooring, furniture, cabinets — and rarely cause structural damage.
What To Do If You Suspect Termites in Your Houston Home
First: do not disturb the suspected area. Breaking mud tubes or disturbing swarmers makes it harder for a technician to assess the colony's location and activity level. Seal the area and schedule a professional inspection.
Second: call a TPCL-licensed termite inspector. A WDI (Wood-Destroying Insect) inspection includes a full assessment of all accessible areas — foundation, crawl space, attic, exterior perimeter — and a written report documenting evidence of infestation, damage, and conducive conditions.
Third: if inspection confirms active termites, treatment should begin within 30 days. Subterranean termite colonies in Houston grow year-round due to the mild climate — delay allows the colony to expand and cause additional structural damage.
A TPCL-licensed technician can confirm subterranean vs. Formosan activity during a termite inspection and recommend the appropriate treatment — liquid termiticide barrier, bait system, or combination approach. Annual reinspection after treatment ensures the colony does not re-establish as new swarmers emerge in subsequent seasons.