How to use ant killer spray
Updated: 22 October 2026
How to use ant killer spray means treating the surface the label names, at that label's rate, and leaving the band until it has done the job the label describes. It does not mean fogging the room, wetting the chopping board, or spraying a trail that already has gel on it. The [Ant spray](/hub/pest-control/ant-spray) comparison holds the five listings. Peter F., editor for DIY & tools at productscompared.co.uk, did not run a laboratory test. A purchase through our links can earn a commission at no extra cost to you.
How to use ant killer spray means treating the surface the label names, at that label's rate, and leaving the band until it has done the job the label describes.
How to use ant killer spray means treating the surface the label names, at that label's rate, and leaving the band until it has done the job the label describes. It does not mean fogging the room, wetting the chopping board, or spraying a trail that already has gel on it. The Ant spray comparison holds the five listings. Peter F., editor for DIY & tools at productscompared.co.uk, did not run a laboratory test. A purchase through our links can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Where it goes | Dose in the texts | What you leave | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Deadfast Deadfast Ant Killer Plus Spray 750 ml | About one metre of trail | About 10 sprays, roughly 10 ml | Do not clean while ants use it | 8.4 | about £6.00 | View offer |
| Best value |  Doff Doff Ant & Crawling Insect Killer Spray 1 litre | Hard surfaces, patios, gardens | Not printed on the saved listing | People and pets off until dry | 6.4 | about £6.00 | View offer |
| Alternative |  Dethlac Dethlac Insecticidal Lacquer 250 ml | Bands on hard surfaces | 15–23 cm, bursts to 5 seconds | Children and pets off until dry | 7.2 | about £7.90 | View offer |
On this page
Before you press the nozzle
Read the label on the can you bought, not a different retailer's page for a similar red can. HSE expects public users to follow the amateur label: the dose, the places, the re-entry line, and the disposal line. A professional-only product is not a stronger version of the same job. If the amazon.co.uk bullets and the bottle disagree, the bottle wins. Clear food, crumbs, and pet bowls. People and animals stay off the wet surface until it is dry. If bats use the roof space or the wall you are about to treat, stop. The label's place of use decides the room, not the trail you can see. An indoor title does not follow the ants onto the patio, and a lacquer does not go onto soil because the nest entrance is in the lawn.
Where the spray goes
Point the nozzle at the trail, the skirting, the door frame, or the entry the ants are using, on a surface the label allows. You are laying a band they must cross, not a cloud in the room. Keep the rates with the product. Deadfast's maker describes about ten sprays, roughly 10 ml, along one metre of trail, and nest entrances outdoors. Dethlac's FAQ describes 15–23 cm, bands about 8–15 cm wide, and bursts of up to five seconds, and it rules out uPVC, drains, and a space spray. Doff's saved listing does not print a dose. A blocked nozzle is a packaging fault, reported for Doff and for Raid. White marks are reported with Dethlac. Test a small patch before you coat a frame.
After you spray
Leave the band until it is dry, and ventilate. Children and pets come back when the surface is dry. One Doff review describes sneezing for about two hours in a confined space. Do not mop the residual the same day. Deadfast's maker says not to clean the line while pests are still using it, and the nest timing is two to three weeks. Waltham Forest says ants may still cross a sprayed edge for days. A downpour can wash a water-based trigger off the slab. If bait is already down, stop. Spraying that run kills or repels the ant that was supposed to carry the gel home.
When a spray is the wrong next step
Stop and call a professional if the ants are tiny, the flat is warm all year, and you cannot match them to black garden ants. Pharaoh ants and ghost ants bud into new nests when a repellent pyrethroid hits the trail. BPCA treats identification as the first step. A nest in a cavity wall, numbers that stay high after the label rate, or illness after a heavy dose or a swallow, is the same handoff. The poisons line on the label is the urgent number. A second can is the wrong next step when the nest has already replaced the foragers. Bait belongs on a clean run, not on the wet film.
Common questions
Where do I actually point the nozzle?
Point it at the trail and the entry on a hard surface the label allows: skirting, door frame, crack, or patio edge. Dethlac's FAQ uses 15–23 cm. Deadfast's maker talks about a metre of trail, not a cloud in the room. Do not aim at the air, at food, or into a drain.
How long do I leave the surface before I mop?
Keep people and pets off until the surface is dry, and do not mop a residual band the same day. Deadfast's maker says to leave the line while ants are still being controlled, with a nest claim measured in two to three weeks. Wiping it that evening removes the residue you just paid for.
Can I spray the air to kill flying ants?
No. These products are for surfaces, cracks, and entries. A space spray is outside Dethlac's instructions, and a few winged ants dropping in the kitchen does not empty the nest. Treat a sudden indoor swarm of tiny ants in a warm block as an identification problem.
What if it rains on a patio I have just sprayed?
A water-based trigger can be washed off a slab if rain arrives before the band has done its job. Wait for a dry surface and apply only where that label allows outdoor use. Do not follow an indoor aerosol onto the patio because the trail started outside.
The nozzle leaked or blocked. Is the formula useless?
A leak or a stuck button is a packaging fault reviewers report for Doff and for Raid, and it is separate from whether the insecticide works on a trail. Stop, and check the nozzle and the seal. White marks from a heavy lacquer coat are a surface problem reported with Dethlac.
When do I stop and call someone?
Call a professional if the ants may be Pharaoh or ghost ants, if the nest is in a wall, or if numbers stay high after you have used the label rate and left the band in place. Call the poisons information on the label if someone has swallowed the product. Bats in the building are a reason to stop.
Related pages
Sources
Public UK sources used for this comparison. Shelf prices, stars and review counts are the amazon.co.uk figures captured for these five listings. Last checked 19 October 2026.
- HSE biocidal labelling (retrieved 19 October 2026)
- HSE home and garden pesticides (retrieved 19 October 2026)
- BPCA ant identification (retrieved 19 October 2026)
- BPCA ant control advice (retrieved 19 October 2026)
- Deadfast Ant Killer Plus Spray (retrieved 19 October 2026)
- Dethlac aerosol (retrieved 19 October 2026)
- Tesco Raid Ant and Cockroach Killer 300 ml (retrieved 19 October 2026)
- Waltham Forest garden ant fact sheet (retrieved 19 October 2026)