What is bifenthrin? A pyrethroid insecticide that kills by contact and ingestion. It is best known for termites: it binds tightly to soil and does not dissolve easily in water, so it forms a chemical barrier that lasts for years around a building's foundations.
How does it work?
It attacks the insect's nervous system: it holds nerve channels open, so the insect is paralysed and dies.
- Fast on insects that touch it.
- Not taken up by plants and does not move inside them.
- Stable in soil and not easily washed away.
Why is it used for termites?
Subterranean termites come from below, from the soil into the foundations. So the treatment is to saturate the soil around and under the building.
Bifenthrin suits the job because it:
- Sticks to soil particles and does not move down with irrigation or rain.
- Stays active for a long time.
- Is repellent: termites sense it and keep away from the treated zone.
Repellent vs non-repellent barriers
This is the key difference to understand before choosing:
| Bifenthrin (repellent) | Fipronil and imidacloprid (non-repellent) | |
|---|---|---|
| Do termites sense it? | Yes, and avoid it | No, they walk through it |
| How it protects | Blocks termites from the building | Termites pick it up and carry it to the colony |
| Eliminates the colony? | No, it deflects it | It can affect it |
| A gap in the barrier | Termites find it and enter | Less of a problem |
So a repellent must be applied with no gaps. Both have their place; the choice depends on the case.
Where is it used?
- Pre-construction: soil treatment before the slab is poured and around footings.
- Post-construction: trenching around foundations, or drilling the floor and injecting.
- Around the outside of the house: a protective band against ants, spiders and crawling insects.
- Timber at risk of attack.
Termite treatment involves large volumes and injection equipment. The rate and volume per metre come exactly from the label.
Key points
- Highly toxic to fish and bees: keep it away from ponds and waterways, and do not spray flowering plants.
- On skin it causes temporary tingling and warmth. Wear gloves and long sleeves.
- Do not under-dose: a weak barrier lets termites through.
- Do not dig or turn treated soil afterwards; it breaks the barrier.
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Bifenthrin FAQs
How long does bifenthrin last in soil?
Years, depending on soil type, rate and temperature. The label gives the expected period.
Does it kill the termite colony?
No, it keeps the colony out of the building. To affect the colony itself you need non-repellent products or bait stations.
Does it work on cockroaches and ordinary ants?
Yes. Its suspension concentrate form is sprayed indoors and outdoors for cockroaches, ants and mosquitoes, with no odour.