How to Get Rid of Formosan Subterranean Termites
Formosan subterranean termites build far larger colonies than the native species and do structural damage on a shorter timeline. If they are what you have, the response needs to be quicker than it would be otherwise.
Bigger colonies, faster damage, and nests that survive above ground.
Formosan subterranean termites are an introduced species now well established along the Gulf Coast and through much of east Texas. What sets them apart from the native eastern subterranean termite is scale: colonies run to the millions rather than the hundreds of thousands, and they forage over a much wider area from a single colony.
The practical consequence is timeline. A structure that might take a native colony years to noticeably damage can be compromised considerably faster. That is the whole reason this species has its own page.
The second difference matters more for treatment. Formosan colonies build carton nests out of chewed wood, soil, and saliva, and carton holds enough moisture that a portion of the colony can live entirely inside a wall void without ever returning to soil. A soil treatment alone does not necessarily reach that.
What a Formosan infestation looks like
Correct identification changes the treatment plan, so it is worth being sure rather than assuming subterranean is subterranean.
A swarm indoors
Formosan swarms are large and, unlike most native subterranean species, happen at night and around lights. Hundreds of winged insects at a window or a porch light on a warm evening in late spring is the signature.
Piles of shed wings
Swarmers shed their wings shortly after landing, so the wings stay behind on windowsills, in door tracks, and around light fixtures long after the swarm itself has gone.
Mud tubes
Pencil-width tunnels of soil and saliva running up a slab, pier, or foundation wall. Formosan colonies build heavily, and the tubes can be considerably more extensive than what a native subterranean colony puts up.
Carton nests
The thing that most distinguishes this species. Formosan termites build a chewed-wood-and-soil nest material called carton, which holds moisture, and it lets a satellite colony survive inside a wall void with no soil contact at all. Finding carton in a wall means the problem is not only under the slab.
Take the moisture away
Subterranean termites of any species need moisture, and Formosan colonies in particular use it to sustain carton nests away from soil. Drying the structure out is not a treatment, but it removes what makes the site viable and it is worth doing before, during, and after one.
- Ventilate crawlspaces, attics, and any enclosed space that holds damp.
- Fix plumbing leaks, including slow ones that never made a visible mark.
- Clear gutters and downspouts, and check that splash blocks actually carry water clear of the foundation.
- Regrade anywhere water pools against the structure.
- Break wood-to-soil contact and inspect what you find when you do.
Soil treatment, baits, and usually both
Soil treatment means applying a termiticide into the ground around the foundation, including through drilled holes where slabs, patios, or walkways sit over the treated line. The result is a continuous treated zone every soil route has to cross. Termidor is one of the products commonly used for this.
Baiting means stations set around the property carrying an insect growth regulator that foraging workers take back to the colony. Sentricon, developed by Dr. Nan-Yao Su at the University of Florida, is the long-standing system in this category, and Formosan termites were much of the reason that research happened. To be clear about a claim that gets made loosely: bait is not chemical-free. It is a small quantity of active ingredient placed where termites will find it rather than a barrier applied to soil, which is a real difference, but it is not the absence of one.
For Formosan specifically, the pairing matters more than it does for native species. The soil zone handles the ground connection; the stations keep working afterward and give you monitoring on a colony large enough that satellite pockets are a genuine possibility.
One thing not to do: reach for an aerosol and treat what you can see. Spot-treating an accessible gallery is how a colony this size splits and relocates into parts of the structure nobody is looking at. Formosan infestations in particular are worth leaving alone until someone has inspected the whole structure.
Living trees are a Formosan reservoir
This species readily infests living trees, which native subterranean termites do far less often. A mature tree in the yard can host a colony that keeps supplying the property long after the structure has been treated, and treating the house while ignoring the tree is a common way for an infestation to come back.
If there are established trees near the structure, they should be part of the inspection. Treating them is possible but it is specialised work, and it is worth flagging when you book rather than discovering afterward.
Exclusion and ongoing cover
- Seal cracks and crevices in the foundation.
- Correct structural issues that trap damp or put untreated wood against soil.
- Inspect regularly rather than waiting for a swarm to announce it.
- Consider a wood-destroying organism contract, usually written as WDO, which is an ongoing inspection and treatment agreement rather than a one-off visit. On a property in Formosan territory that continuity is worth more than it is elsewhere.
This is the species to move quickly on
Colony size and the possibility of carton nests inside walls mean the inspection needs to cover the whole structure and the grounds, not just where the signs are. Our termite technicians can identify the species and scope it properly.
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