Drywood Termite Signs in San Antonio Homes: What to Look For

Drywood termites don't need soil. They extract moisture directly from the wood they consume, which means they can establish inside a door frame, a fascia board, a piece of furniture, or a structural rafter with no contact with the ground at all. A drywood colony lives entirely within whatever wood it infests.

This self-contained lifestyle makes drywood termites uniquely portable. Infested furniture moved from one home to another can introduce a colony to a new location. Infested lumber used in construction or renovation can seed a new infestation. In San Antonio, drywood termites are most commonly found in wood trim, door and window frames, attic rafters, and furniture, particularly older pieces with unfinished wood surfaces.

Frass is the most distinctive sign of drywood termite activity. Drywood termites push their fecal pellets out of the colony through small kick-out holes in the wood surface. The pellets are hard, six-sided, and uniform in size, typically about one millimeter in length. They accumulate in small piles on windowsills, along baseboards, on attic floors, or on any horizontal surface below an infested piece of wood. The color of the pellets varies from cream to dark brown depending on the type of wood the termites are consuming.

Swarmer (alate) activity is the other primary indicator. Drywood termite swarmers emerge from colonies when the population reaches a threshold size, typically in late summer in Texas. The swarmers fly toward light and are often found at windowsills or light fixtures. Finding scattered wings (termite swarmers drop their wings after flight) is significant evidence of a colony somewhere in or near the structure.

Drywood termites most commonly enter through unfinished or poorly finished wood surfaces, end grain on trim boards, bare wood inside attic spaces, unpainted wood on the back of door frames, and gaps in paint or sealant on exterior wood. In San Antonio, the combination of intense UV light and temperature cycling degrades exterior paint and caulk relatively quickly, creating entry opportunities on even well-maintained homes.

Inspect attic spaces annually for frass on top of insulation or on attic floor surfaces. Check the exposed end grain of rafter tails at the roofline, garage door frames (often left unpainted on interior surfaces), exterior window trim, and any decorative wood features. Interior inspections should focus on areas where evidence (frass or wings) has been found.

Two treatment approaches exist for drywood termites: localized treatment and whole-structure fumigation. Localized treatment (injecting a liquid or foam termiticide directly into galleries through drilled ports) is appropriate when the infestation is confined to one or two identified pieces of wood. It is less disruptive than fumigation and does not require vacating the structure for multiple days.

Whole-structure fumigation with sulfuryl fluoride is the most complete treatment available and is recommended when the infestation is widespread, when multiple locations are confirmed or suspected, or when the infestation is in areas that cannot be fully accessed for localized treatment. Fumigation requires vacating the structure for approximately 48 to 72 hours and removes all gas-phase fumigant after the treatment period, leaving no residual protection, a follow-up inspection and preventive treatment is advisable.

Drywood termites cannot infest wood that is fully painted or sealed, because they require an unfinished surface to begin excavating. Maintaining paint and exterior caulk on all wood surfaces (particularly end grain and any wood-to-masonry joints) is the most effective preventive measure available to homeowners. Pay particular attention to wood trim at the roofline and around garage door openings, where paint wear is most rapid.

Inspecting any used furniture before bringing it indoors, particularly antique or reclaimed wood pieces, reduces the risk of inadvertent introduction. Frass inside a drawer or on a shelf beneath a wood piece is a reliable indicator of an active infestation that should be addressed before the item enters the home.