Yes, bifenthrin kills termites. It is one of the more effective insecticides used against them, ranking high in toxicity comparisons with other common termiticides. Products like Bifen IT and Bifen XTS contain bifenthrin as their active ingredient and are widely used for both pre-construction and post-construction termite barriers around homes.
How Bifenthrin Kills Termites
Bifenthrin is a synthetic pyrethroid, a class of insecticides that disrupts the nervous system of insects on contact. It interferes with nerve signal transmission, causing symptoms like loss of coordination and paralysis before death. In termites specifically, the most commonly observed effects are moribundity (a state of near-death sluggishness) and visible intoxication in worker termites.
What makes bifenthrin particularly useful against termites is its slow-acting mechanism. At lower concentrations, termites cannot detect it in the soil. Foraging workers walk through treated areas, pick up the chemical, and carry it back to the colony on their bodies. This gives the poison time to spread through the colony before individuals start dying, which can lead to broader colony damage rather than just killing the few termites that directly contact the treated zone.
In head-to-head comparisons with other termiticides, bifenthrin ranked second in overall toxicity to termite workers, behind chlorantraniliprole but ahead of fipronil and chlorpyrifos. The time it takes to kill 50% of exposed termites decreases as concentration increases, meaning higher application rates produce faster results. Temperature also plays a role: bifenthrin performs better in warmer conditions, which is worth noting if you’re treating soil during cooler months.
Bifen IT vs. Bifen XTS
The two most common bifenthrin products for pest control are Bifen IT and Bifen XTS, and they are not interchangeable when it comes to termites. Bifen IT is the standard formulation used for general pest control and termite barrier treatments around structures. It’s the product most commonly mixed with water and applied to soil around foundations.
Bifen XTS contains a higher concentration of bifenthrin (25.1%) and is formulated as an oil-based emulsifiable concentrate. It penetrates porous surfaces like wood and bark far better than Bifen IT, which makes it the preferred choice for wood-boring beetles and bark-infesting pests. While Bifen XTS does list termites on its label, the product notes indicate termite treatment is “not recommended” as a primary use case for perimeter application around buildings. For a standard soil termite barrier, Bifen IT is the appropriate product.
How Long the Barrier Lasts in Soil
Bifenthrin is the most persistent of the synthetic pyrethroids in field conditions. Its half-life in soil ranges from about 4 months to nearly a year, depending on soil type and how much air circulates through the ground. Heavier, compacted soils tend to preserve it longer, while loose, well-aerated soils break it down faster.
Sunlight does not significantly degrade bifenthrin, which is one reason it works well as a subsurface barrier beneath concrete slabs or in trenches around foundations where UV exposure is minimal. In practice, professional termite barriers using bifenthrin are typically reapplied on a schedule rather than assumed to last indefinitely, since soil moisture, microbial activity, and other environmental factors gradually reduce its concentration below effective levels.
How Bifenthrin Is Applied for Termites
For pre-construction treatment, bifenthrin is applied as a layer in the soil beneath where a concrete slab will be poured. This creates a chemical barrier between the ground and the structure before the building even goes up. Some newer installations use drip irrigation systems around a home’s perimeter to distribute bifenthrin into the surrounding soil on a scheduled basis.
For post-construction treatment, the standard approach involves trenching around the foundation of an existing home, applying the diluted bifenthrin solution into the trench, and backfilling. The goal is to create a continuous treated zone in the soil that termites must pass through to reach the structure. Gaps in the barrier, such as areas where plumbing penetrates the slab, are common weak points that need targeted treatment.
Environmental Risks to Consider
Bifenthrin is considered relatively safe for humans and other mammals, but it is highly toxic to aquatic life. It doesn’t dissolve in water, so in theory it shouldn’t wash into storm drains. In practice, it binds to soil particles and dust that do get carried by rainwater into local waterways. Research from the University of Melbourne found that 40 out of 99 surveyed wetlands near urban areas had sediment contaminated enough with bifenthrin to kill native aquatic invertebrates. Environmental regulators in both Australia and California have flagged bifenthrin runoff as a significant concern for urban waterways.
Because bifenthrin persists in the environment, any amount that reaches a stream, pond, or wetland sticks around and accumulates over time. If your property borders any body of water or drains into a storm system that feeds into one, careful application matters. Avoid treating soil on slopes where runoff is likely, and don’t apply before heavy rain is expected. The same persistence that makes bifenthrin effective as a termite barrier makes it a long-term problem if it ends up somewhere it shouldn’t be.