Spot treating termites means targeting a single board or small cluster of infested wood rather than treating your entire home. It costs between $200 and $900, works best for small, contained drywood termite colonies, and can be done with chemical injections, foam, heat, or even microwave devices. The catch: it only works when you’ve accurately located every colony, and drywood termites can have multiple hidden infestations throughout a structure.
When Spot Treatment Makes Sense
Spot treatment is appropriate when termite activity is genuinely limited to a specific area, like a single window sill, door frame, or rafter. A pest inspector typically identifies these sites by probing wood, looking for frass (the tiny pellets drywood termites push out of their galleries), or using detection tools. If the infestation is confined and accessible, there’s no reason to fumigate an entire house.
The biggest risk is missed colonies. Drywood termites live entirely inside wood, with no mud tubes or connection to the soil, so multiple colonies can exist in walls, roof framing, and other hidden areas without obvious signs. If your inspector finds damage in several locations or suspects activity behind walls that can’t be reached, spot treatment alone probably won’t solve the problem. As the Texas Department of Agriculture puts it plainly: a wood-penetrating fumigant gas is the only sure way to reach every colony in a structure.
Chemical Spot Treatments
The most effective chemical spot treatments involve drilling small holes into infested wood and injecting a liquid or foam product directly into termite galleries. For the chemical to work, termites must physically contact it or ingest it. That’s why drill placement matters enormously. A California Structural Pest Control Board study found that spacing drill holes every 5 inches in a diamond pattern dramatically improved results compared to wider spacing at 18 inches.
Not all products perform equally. In that same study, a fipronil-based liquid (Termidor) achieved 92% kill of worker termites at 30 days when injected at standard 18-inch spacing, and 100% kill at tighter 5-inch spacing. A thiamethoxam-based foam (Optigard) reached 73% to 81% kill depending on spacing. A borate-based liquid (Tim-bor) performed poorly at wide spacing, killing only 20% of workers, but jumped to 99% at closer intervals. Orange oil and other botanical products have shown questionable results in university field tests.
The fipronil and thiamethoxam products also have staying power. Even 60 days after application, dried residues of both chemicals killed 100% of termites within a week of contact. Borate products took longer but still reached full kill within two weeks on aged deposits. This residual activity matters because termites that weren’t in the treated gallery at the time of injection may wander into it later.
Non-Chemical Options
Four non-chemical approaches can be used for localized treatment: heat, microwave, electrocution, and wood replacement.
- Heat: A professional directs heated air into the infested area to raise the wood temperature high enough to kill the colony. Heat can be applied to a single section or scaled up to treat an entire structure. It requires no chemicals but demands careful monitoring to avoid damaging heat-sensitive materials nearby.
- Microwave: A handheld device directs microwave energy into the wood, essentially cooking the termites by boiling the fluids inside their cells. It’s portable and chemical-free, but it only reaches termites directly in the device’s path, so precise detection is critical.
- Electrocution: A device sends 90,000 volts at very low current (less than 0.5 amps) through the wood. Termites die from electric shock, and survivors may die later because the electricity destroys the gut organisms they depend on to digest wood.
- Wood replacement: Simply cutting out and replacing the infested board or framing member. It’s straightforward but only works if the colony hasn’t spread beyond the piece you’re removing.
Every non-chemical option shares the same limitation as chemical spot treatment: success depends almost entirely on finding the full extent of the infestation before you begin.
Cost Compared to Fumigation
Spot treatment typically runs $200 to $900, with minor infestations in a single accessible area often falling in the $200 to $500 range. Full-structure fumigation (tenting), by contrast, costs $1,200 to $3,500 or more depending on the size of the home. For a typical 1,500 to 2,000 square foot house with moderate drywood termite activity, expect $1,500 to $2,800 for fumigation.
The price difference is significant, but the comparison isn’t always apples to apples. If spot treatment misses a hidden colony and you need a second treatment or eventually resort to fumigation anyway, the total cost climbs. Spot treatment saves money when the infestation is truly small and well-defined. For homes with damage in multiple rooms or inaccessible areas, fumigation is often more cost-effective in the long run because the gas penetrates every void in the structure.
Why Detection Accuracy Matters Most
The single biggest factor in whether spot treatment succeeds isn’t which chemical you use or which device your technician brings. It’s whether the full extent of the infestation was correctly mapped before treatment began. Drywood termites can maintain separate colonies in different parts of a home, and colonies hidden inside wall cavities or roof structures may produce no visible signs for years.
A thorough inspection should include probing exposed wood, checking attic framing, and looking for frass piles near baseboards, window frames, and ceiling joints. Some inspectors use acoustic detection, infrared cameras, or moisture meters to find activity behind finished surfaces. If there’s any doubt about how far the damage extends, treating only what you can see risks leaving active colonies in place. In those cases, the more aggressive option, whether that’s broader chemical treatment or full fumigation, is the more reliable choice.