Texas is home to several subterranean termite species, and they’re active across virtually every part of the state. The two most economically important are the eastern subterranean termite and the Formosan subterranean termite, both serious threats to wooden structures. Understanding which species you’re dealing with, when they swarm, and how to spot early damage can save you thousands of dollars in repairs.
Species Found in Texas
The most common subterranean termites across the state belong to the genus Reticulitermes. One species ranges from east Texas westward to the Uvalde and Tom Green County areas, while another extends from east Texas to Bexar and Eastland Counties. These are small, pale insects that live in underground colonies and travel through soil or self-built mud tubes to reach wood above ground.
The Formosan subterranean termite is the more destructive invader. First discovered in 1956 around the Houston Ship Channel in Pasadena, it has since been detected in 31 Texas counties, with more added each year. Formosan termites have been reported in all major metropolitan areas in the state, including Dallas, San Antonio, Austin, and Houston. They’re larger than native subterranean termites, with pale yellow bodies and oval-shaped soldier heads. Their colonies can number in the millions, compared to hundreds of thousands for native species, which means they can inflict damage much faster.
One way Formosan termites continue spreading is through recycled wood products. Infested lumber reused as landscaping timbers or retaining walls can carry a colony right into a new property. Although the highest concentration remains in the upper Gulf Coast region, isolated infestations can appear anywhere in Texas.
When Termites Swarm
Subterranean termite colonies take three to five years to mature before they produce their first swarmers, the winged adults that leave to start new colonies. In Texas, swarming typically happens between February and May, when fully mature colonies send out flying reproductives to search for new nesting sites. Warm days following rain are the most common trigger, and swarms usually occur during daylight hours.
Seeing swarmers outdoors near tree stumps or landscape timbers doesn’t necessarily mean your house is infested. It simply confirms that termite colonies are active in your area. Indoor swarms are a different story. If winged termites emerge inside your home, it usually means an active infestation is already established somewhere within the structure. You may also find small piles of shed wings near windowsills or light fixtures, since swarmers drop their wings shortly after landing.
Signs of an Active Infestation
Subterranean termites never roam out in the open. They either tunnel through soil directly into wood or build mud tubes to travel between the ground and their food source. These pencil-width tubes, made from soil, wood particles, and saliva, are the most visible evidence of activity. You can find them on foundation walls, floor joists, hanging from sub-flooring, or tucked into cracks between structural members. They sometimes appear inside cellulose-based drywall and insulation as well.
Tubes found along ceilings or on upper floors of a building suggest an above-ground colony that may not need direct contact with the soil. These aerial tubes often contain materials other than soil, such as fragments of wood or drywall, whatever the termites are feeding on.
Other signs to look for:
- Hollow-sounding wood when tapped with a screwdriver handle
- Soft, easily probed wood that a knife or screwdriver pushes into without resistance
- A thin gritty film on the surface of damaged material, gray-brown in color
- Old mud tube remnants that are dry and crumble easily, leaving visible etching on surfaces (a sign of past activity, though not necessarily a current infestation)
How Treatment Works
There are two main approaches to treating subterranean termites, and most pest control companies use one or a combination of both.
Liquid Soil Barriers
The traditional method involves applying a liquid termiticide into the soil under and around the building’s foundation. This creates a chemical barrier that termites can’t cross without being exposed. The most reliable products are non-repellent, meaning termites can’t detect and avoid them. Instead of simply blocking entry, these chemicals are lethal on contact or shortly after, and termites that walk through treated soil carry the product back to their colony on their bodies.
Bait Systems
Baiting takes a completely different approach. Small plastic stations are installed in the ground around your home’s perimeter. Each station contains a cellulose material combined with a slow-acting insecticide that disrupts the termites’ ability to molt. Termites that find the station feed on the bait and leave behind a colony-specific scent that recruits other workers to the same location.
The slow action is deliberate. If termites died immediately, dead insects would pile up near the stations and other colony members would learn to avoid the area. Instead, the toxin spreads through the colony as foragers share food with nest mates, including those that never visited a station. Entire colonies can be eliminated this way, though it takes weeks to months rather than days. Common professional bait systems include Sentricon, Exterra, and Trelona Advance.
Preventing Infestations
Subterranean termites need moisture to survive, which is why water management around your home is the single most important preventive step. Make sure gutters and downspouts direct water away from the foundation. Fix leaky faucets and air conditioning drip lines, especially those near exterior walls. Grade the soil around your foundation so it slopes away from the house rather than pooling against it.
Wood-to-soil contact is the easiest entry point for termites. Keep firewood, lumber, and mulch at least several feet from the foundation. If you use landscape timbers or wooden raised beds, avoid placing them directly against the house. Be especially cautious with recycled wood products, since Formosan termites frequently spread through infested lumber repurposed for landscaping.
Inside crawl spaces and basements, reduce humidity with proper ventilation. Foam board insulation that extends below grade can hide mud tubes from view during inspections, so consider leaving a visible gap of exposed foundation between the soil line and any exterior cladding. Regular visual inspections of your foundation walls, particularly after warm spring rains during peak swarming season, are one of the simplest ways to catch a problem early.
Native vs. Formosan: Why It Matters
If you’re in the Houston-Galveston corridor, Beaumont-Port Arthur area, or any of the 31 confirmed counties with Formosan activity, the stakes are higher. Formosan colonies are dramatically larger and consume wood at a faster rate. They’re also more likely to establish aerial colonies that don’t maintain a direct connection to the ground, making them harder to control with soil-applied treatments alone. Bait systems can be especially effective against Formosan termites because of how aggressively these termites recruit nestmates to food sources.
For homeowners in west Texas or the Panhandle, native subterranean species are the primary concern. They cause damage more slowly but are still capable of significant structural harm over time, particularly in older homes with untreated wood framing or poor drainage. Regardless of where you live in Texas, annual professional inspections remain the most reliable way to catch termite activity before it becomes a costly repair.