The first fortnight after an ant treatment can feel unsettling: you may see more ants rather than fewer for a day or two. That's usually the treatment working. What you do, and don't do, in that window makes a real difference.
The first week
- Don't wash or spray where the technician treated. Outdoor products along paths and walls need to stay in place. Hold off water-blasting paths and washing the house for as long as the technician says.
- Leave the bait alone. If ants are feeding at a bait spot, let them. Wiping them up or spraying them cuts off the delivery route to the nest.
- Keep other food away. Clear benches, seal pantry items and rinse recycling, so the bait is the most interesting thing on offer.
- Keep pets away from treated areas for as long as you were told.
Weeks two to six
Numbers should fall clearly within one to two weeks. Small trails can reappear as a neighbouring nest finds its way in, which is common with Argentine ants. If the activity is still strong after two weeks, or comes back in force, tell the business that treated it. Most follow-ups are booked in this window.
Keeping them out longer
Close the gaps once the ants are gone
When the trail has been quiet for a couple of weeks, seal the entry points you can see: gaps along skirtings and bench backs, around pipes under sinks, and where cables come through walls. Sealing too early just makes ants find a new door.
Break the bridges
- Trim branches and shrubs back so they don't touch the house, roof or deck.
- Move pot plants off the edge of decks and away from doors, and check new plants before they come inside. Landcare notes that Argentine ants are often spread in potted plants and soil.
- Keep mulch and garden beds a little back from the house walls.
Remove the reasons to visit
- Feed pets at set times and lift the bowl afterwards.
- Fix dripping taps and leaks. Ants come in for water in dry spells as well as food.
- Keep bins lidded and away from the back door.
- Clean up fallen fruit and honeydew-producing pests, such as aphids and scale on garden plants, which Argentine ants farm for sugar.
Seasonal treatment
Argentine ants are most active in summer, roughly January to March in Auckland, though Landcare notes they can stay active through winter in the upper North Island. Homes with a long-running Argentine ant problem sometimes book a perimeter treatment each spring, before numbers build up. Whether that's worth it depends on how bad your summers have been.
Ant control questions
How long does an outdoor ant treatment last?
It varies with the product, the surface and the weather. Sun, rain and water-blasting all shorten it. Ask the technician what to expect for the product they used.
The ants are back after a month. Was the treatment a failure?
Not necessarily. With Argentine ants, nests on neighbouring properties can move back in. Tell the business that treated it; many offer a re-treatment within a set period.
Do natural deterrents work after a treatment?
Strong smells such as peppermint or vinegar can push a trail somewhere else for a day or two, but they don't affect the nest. Removing food and water and closing gaps does more.
Where these facts come from
Checked 27 October 2026