The highly invasive Asian subterranean termite (Coptotermes gestroi) poses a significant threat to wooden structures in tropical and sub-tropical regions. This species causes extensive structural damage due to its aggressive foraging behavior and immense colony size. Homeowners must understand the signs of an active infestation and the professional strategies available for management to protect their property. This guide provides an overview of identifying and controlling this destructive pest.
Profile of Brazilian Termites
The Asian subterranean termite (C. gestroi) is a highly destructive pest known for its ability to rapidly consume cellulose materials, including structural wood, paper, and cardboard. Colonies of this species can grow exceptionally large, containing millions of individuals. They maintain a subterranean lifestyle, requiring a connection to the soil for moisture, which allows them to enter structures through cracks and utility conduits.
These termites are organized into three primary castes: workers, soldiers, and reproductives (alates). The soldiers possess a distinct teardrop-shaped head and a specialized nozzle-like structure called a fontanelle, which secretes a defensive, sticky fluid. This head morphology is a key feature used by professionals to distinguish them from native subterranean termites. Their foraging distance can be extensive, allowing them to attack multiple, distant food sources simultaneously.
Recognizing Infestation Signs
Homeowners should remain vigilant for three distinct physical indicators of active termite activity. The most common sign is the presence of mud tubes, which are pencil-width tunnels constructed from soil, wood debris, and saliva. These tubes allow termites to travel between the soil and a food source while maintaining the high humidity necessary for survival. Look for these protective tunnels along foundation walls, in crawl spaces, and along baseboards.
A second major sign is the appearance of swarmers (alates) and their discarded wings, typically occurring during warm, humid evenings. Swarmers are the reproductive caste that leaves the mature colony to establish new ones; finding them indoors indicates an active interior infestation. After a brief flight, they shed their wings, leaving small piles often found near windowsills, light fixtures, or doors.
Wood damage is the third indicator, although this often occurs when the infestation is already advanced. Termites consume wood from the inside out, leaving only a thin outer layer of paint or veneer intact. This results in wood that sounds hollow when tapped or surfaces that appear blistered or show bubbling paint. In severe cases, the damage may cause floors to buckle or doors and windows to fit tightly as structural integrity is compromised.
Eradication and Treatment Methods
Managing an established Brazilian termite infestation requires professional intervention, as common do-it-yourself methods are ineffective against such large colonies. Professionals primarily use liquid soil treatments and baiting systems, sometimes in combination. Liquid soil treatments involve applying a termiticide to the soil around the structure’s perimeter, creating a continuous protective barrier. Modern products use non-repellent formulations, allowing termites to pass through the treated soil without detection, picking up the active ingredient.
Once exposed, the termiticide is spread throughout the colony through contact and social interaction, leading to colony elimination. This method offers immediate protection to the structure and is often preferred for its swift action. However, any gap in the treated zone, such as deep utility penetrations or untreated concrete expansion joints, can allow termites to bypass the barrier.
Baiting systems offer an alternative approach focused on colony elimination rather than exclusion. These systems use cellulose-based bait infused with a slow-acting toxicant, typically a Chitin Synthesis Inhibitor (CSI). Worker termites consume the bait and share it with the rest of the colony, including the queen, through a process called trophallaxis. CSI prevents the insects from properly molting, leading to a gradual but complete collapse of the entire colony over several weeks or months.
For C. gestroi, research shows that in-ground bait stations are often ignored. Therefore, above-ground bait stations placed directly on active feeding sites inside the structure are highly effective for rapid toxicant dissemination. In cases of extreme structural damage, fumigation may be used, which involves tenting the building and introducing a gaseous pesticide to eliminate all termites instantly. Fumigation is reserved for severe infestations where other methods cannot guarantee complete eradication.
Proactive Infestation Prevention
Reducing the conditions that attract subterranean termites is the most effective way to prevent future infestations. Since these pests require a constant source of moisture, controlling water around the home’s foundation is a primary defense. Ensure that all gutters and downspouts direct rainwater at least ten feet away from the structure and that the soil slopes away from the foundation to prevent water accumulation.
Fixing any plumbing leaks, including dripping faucets or air conditioning condensate lines, is necessary to keep the soil dry near the house. Homeowners should also eliminate all wood-to-ground contact, as this creates a direct entry point for termites. This includes removing wood debris, keeping firewood elevated and away from the foundation, and ensuring wood siding is several inches above the soil line.
Reducing humidity in crawl spaces through proper ventilation and the installation of a vapor barrier also makes the area less hospitable to termites.