Termite foam is the primary DIY tool for treating drywood termite colonies in accessible wood. Unlike liquid termiticides applied to soil, foam is injected directly into the termite gallery network through small drilled holes or through the colony’s own kickout hole. The expanding foam carrier travels through the gallery, coating workers, soldiers, and reproductives with an insecticide that kills them on contact. The foam then collapses and dries, leaving a residual insecticide film on the gallery walls that kills any workers that return to the treated zone. When combined with a borate surface treatment on surrounding wood, foam injection provides reliable control of localized drywood termite colonies in attic framing, window frames, door frames, structural lumber, and furniture.
The products below are all available through Amazon and are suited for homeowner DIY use. The step-by-step injection process, including gallery mapping, drilling, and hole sealing, is in the how to treat drywood termites guide.
What to Look for in a Termite Foam
Active ingredient determines how the foam kills termites and how long the residual protection lasts in the gallery. Fipronil foam, available in Termidor Foam, is non-repellent: workers that contact it cannot detect it and continue moving through the gallery, picking up the active ingredient on their bodies and spreading it to nestmates through trophallaxis. This transfer effect is the same mechanism that makes fipronil soil treatments effective against subterranean termites, and it is equally valuable in a drywood gallery treatment where the colony may extend into gallery sections the foam does not directly reach. Imidacloprid and permethrin foams provide reliable contact kill with a somewhat shorter residual period than fipronil.
Expansion ratio affects how far a single injection travels through a gallery. A foam with a high expansion ratio, typically expressed as how many times the volume expands on contact with air, will travel further from the injection point through a gallery than a low-expansion foam. For deep or branching galleries, higher expansion ratio reduces the number of injection points needed. For shallow or tightly confined galleries in furniture or thin trim pieces, a more controlled lower-expansion foam can be easier to manage without forcing excess foam back out of the injection hole.
Nozzle design determines whether the foam can be injected through a kickout hole directly or whether drilled holes are required. Products with a narrow tube nozzle can sometimes be inserted into an existing kickout hole without drilling, which is useful for accessible infestations in furniture and exposed framing. Products with a wider aerosol nozzle require drilled entry holes, but are easier to use for wall void applications where the entry point is a deliberate hole rather than a natural opening.
Termidor Foam: Best Overall for Colony Elimination
Termidor Foam is the fipronil-based foam product from the same manufacturer as Termidor SC, and it is the most widely used professional and DIY foam termiticide for drywood termite treatment in the US. Its 0.005% fipronil formulation delivers the transfer effect that sets fipronil apart from other insecticide classes: workers that contact the foam carry active ingredient back to nestmates they have not yet reached in the gallery, extending the treatment’s reach beyond the foam’s physical travel distance.
Termidor Foam is available in aerosol cans on Amazon with an injection straw nozzle that fits into small drilled holes. Each can treats a significant number of injection points, and the foam expands at a manageable ratio that makes it easy to control the volume injected per point without overfilling. It is odorless after application and the foam collapses and dries within a few hours, leaving a fipronil-coated residual film in the gallery. The residual film continues to kill any workers that return to the gallery after the initial treatment.
Active ingredient: Fipronil 0.005% Mechanism: Non-repellent, contact kill with transfer effect Nozzle: Injection straw, suits drilled holes Best for: Most drywood infestations, attic framing, structural wood, confirmed gallery locations
BioAdvanced Termite Killer Foam: Best Value for First-Time Use
BioAdvanced Termite Killer Foam uses imidacloprid as its active ingredient and is packaged as a consumer-grade aerosol foam. It is available on Amazon in a format familiar to most homeowners, with clear label instructions oriented toward first-time users. The foam expands on injection, travels through the gallery network, and provides contact kill through the imidacloprid active ingredient. It does not provide the same transfer effect as fipronil, but it is effective for accessible, well-mapped galleries where the foam can be directed to reach the colony directly.
BioAdvanced Termite Killer Foam is more widely available in physical retail locations as well as Amazon, which is useful if a treatment needs to be started quickly without waiting for delivery. The price point is lower than Termidor Foam per can, making it a practical first-treatment option for smaller or more localized infestations. For deeper or more extensive galleries where the transfer effect of fipronil would provide more reliable coverage, Termidor Foam remains the stronger choice.
Active ingredient: Imidacloprid Mechanism: Contact kill, no significant transfer effect Nozzle: Aerosol with straw Best for: First-time users, smaller localized infestations, accessible gallery locations
Tim-bor Professional: Best Borate Option for Preventive and Surface Treatment
Tim-bor is a disodium octaborate tetrahydrate (boron) product that is mixed with water and applied as a surface treatment to unfinished wood rather than as an injected foam. It belongs in this comparison because it is the standard companion treatment to foam injection: after foam kills the active colony, Tim-bor applied to all surrounding wood surfaces prevents the colony from relocating to adjacent untreated areas and provides lasting protection against new infestations.
Boron disrupts termite digestion, and workers that consume Tim-bor-treated wood accumulate the mineral through their gut wall in quantities that are lethal over time. Tim-bor solution penetrates into wood fibers and remains effective as long as the treated wood stays dry and unpainted. It is odorless, has very low mammalian toxicity, and is OMRI-listed for use in organic production, making it one of the lowest-risk active ingredients available for structural wood treatment. A single bag of Tim-bor concentrate mixes into multiple gallons of solution sufficient to treat all the exposed framing in an average attic.
Tim-bor is not a foam product and cannot be injected into galleries in the same way as aerosol foams. It is most effective when applied generously to all accessible wood surfaces in the treatment area alongside a foam injection treatment. Bora-Care, a more concentrated borate product that uses a glycol carrier for deeper wood penetration, is an alternative for situations where deeper penetration is needed such as thick timbers or dense hardwood.
Active ingredient: Disodium octaborate tetrahydrate (boron) Mechanism: Disrupts termite digestion on contact with treated wood Application: Surface brush, roller, or low-pressure spray; not for gallery injection Best for: Preventive wood treatment, companion surface treatment after foam injection, new construction or renovation
Product Comparison
| Product | Active Ingredient | Application Type | Transfer Effect | Best For |
|---|---|---|---|---|
| Termidor Foam | Fipronil 0.005% | Gallery injection | Yes | Colony elimination, most infestations |
| BioAdvanced Termite Killer Foam | Imidacloprid | Gallery injection | Minimal | First-time use, accessible infestations |
| Tim-bor Professional | Disodium octaborate tetrahydrate | Surface treatment | N/A | Preventive treatment, surface companion to foam |
Using Foam and Borate Together
The most effective DIY approach for a localized drywood termite colony combines foam injection to address the active colony in the gallery with Tim-bor or Bora-Care surface treatment on all surrounding wood to create a treated zone the colony cannot relocate into. Inject foam through drilled holes along the mapped gallery path first, allow it to cure and collapse, seal the holes, and then apply borate solution to all exposed wood surfaces within at least two feet of the treatment area. The foam eliminates the colony; the borate provides lasting protection against any surviving workers and against new colonies establishing in the same wood in future seasons.
The full step-by-step process for locating galleries, drilling injection holes, applying foam, and following up with borate surface treatment is in the how to treat drywood termites guide. For context on when localized foam treatment is the right approach versus when the infestation scope warrants professional fumigation, see the how to get rid of termites guide.