Ants
How to get rid of ants in the house
A practical order of work for ants in the kitchen, in the walls or nesting inside the house: find where they come in, bait them properly, then seal the gap.
The short answer
Follow the trail both ways first, so you know where the ants get in and what they are after. Then take away the food and water, put a slow-acting bait on the trail and outside where it starts, and leave the trail alone for a week or two while the workers carry the bait home. Seal the gap once numbers fall. Spraying the line is the step that makes it worse, which is why professional ant control uses bait.
Find where they are coming from before you kill anything
Watch the trail in the warmest part of the day and follow it both ways. One end is the food or water the ants want, and the other is the way in, which is nearly always along an edge, such as a skirting board, a pipe, a cable, a window frame or the gap under a door, because ants prefer to travel along the structure of a house rather than across open floor.
Indoors, check under the sink, inside the cupboards and along every pipe and electrical wire that comes through a wall, which is where University of California guidance says to look first. Outside, follow the trail to the base of the wall, along the edge of a path, or up a shrub or a citrus tree covered in aphids. Knowing which ant it is changes the plan, too: light brown, fast and unbroken usually means Argentine ants, which need a different approach set out in our guide to Argentine ants.
If the trail seems to start from nowhere, let the ants show you. Put a small dab of bait where you see the most of them and watch the workers that have fed: they head straight home, and the line they take leads to the gap they are using, often one you would never have spotted, behind an appliance or where a cable comes through the floor. Do not wipe anything until you have followed it.
The order that gets rid of ants in the house
Five steps, in this order: take away what the ants came for, bait the trail and the place it starts, leave the trail alone while the bait works, deal with any food source outdoors, and seal the way in once the numbers fall. Each step has a reason, and doing them out of order, especially sealing or spraying first, is why so many ant problems in the house drag on.
Take away what they came for. Sugar, honey, fruit, pet food, crumbs and a dripping tap are what bring ants indoors. Clean the bench and the floor around the trail, but once the bait is down, leave the trail itself alone.
Bait the trail and its source. Use a slow-acting bait that the workers carry back and share, inside beside the trail and outside where the trail starts. The exception is Argentine ants, which are better baited mostly outside, because indoor bait can draw more of them in. The different types, and which suits which ant, are set out in gel, liquid and granular baits and bait stations compared.
Leave the trail alone. Numbers rise for a few days as the workers recruit to the bait, and that is the bait working. Expect fewer ants within about 5 to 10 days and the whole job to take several weeks.
Deal with the food outdoors. Aphids, mealybugs and scale insects on citrus, roses and hedges produce the honeydew that feeds ant colonies, and while that supply is there a colony has every reason to stay.
Seal the way in once numbers fall. Caulk the crack, gap or pipe entry the trail used. Sealing it first only moves the trail to the next gap, and leaves the colony you have not yet baited with a new route in.
Ants in the kitchen
Kitchens draw ants because they put sugar, grease, crumbs, pet food and water in one place. The fix is the same order of work, plus storage: screw-top jars with good seals, pet food in a tub with a tight lid, nothing sweet left out overnight and the sink wiped dry before bed, so the foragers find nothing worth recruiting the rest of the colony to.
Argentine ants are the exception to trusting a jar, because Landcare Research has recorded them getting into cupboards and even sealed jars, so in a bad week the fridge is the safe place for anything sweet. Put bait behind the toe-kick or at the edge of a cupboard where the trail runs, rather than on the bench, which keeps it out of reach of children and pets and away from the food.
If the trail runs to the sink, the dishwasher, the bathroom or the laundry rather than to food, the ants are after water. That usually means a slow leak behind a cabinet, a dripping trap or a failed seal, and fixing it does more than any bait, because a colony with water on tap has a reason to keep coming back.
Ants coming out of the walls, or nesting inside the house
A trail coming out of a power point, a skirting board or a window reveal means the ants are nesting in that cavity or travelling through it. You cannot reach the nest and should not try. Put bait at the point where they come out, leave it, and look outside for the place where they get into the wall, because that is the gap you will eventually seal.
Do not spray into the cavity, and do not take the cover off a power point or a light switch, which is an electrical risk and only pushes the colony deeper into the wall. The ant that most often nests inside Auckland walls is the white-footed house ant, black with pale feet, and it is the hard one for home baiting, because Landcare Research notes that its workers do not pass food on to one another. If a fortnight of bait has not dented the trail, that is the time to call someone.
Should you destroy an ant nest? Only an outdoor one you can see in a path, a lawn or a pot, and only if those are the ants coming inside. Garden ants that stay in the garden can be left where they are, and digging out a nest you cannot fully reach just moves the colony somewhere else.
Why are there suddenly so many ants in the house?
Usually it is the season, because colonies grow quickly from spring and need more food for their brood. The other common causes are a change in the weather, which makes nests move; a new food or water source indoors; a plant against the house carrying aphids or scale insects; and a recent spray that has split one colony into several.
Landcare Research's work on Argentine ants found that workers pick up their eggs and larvae and move the whole nest in response to changes in weather, disturbance and food supply, so a sudden trail after a wet week or a dry spell is often a nest that has just moved closer to the house. As for black ants in particular, in an Auckland house they are most often white-footed house ants, which Te Ara describes as the most common introduced ant in New Zealand.
What kills ants in the house overnight?
Honestly, nothing that lasts. Vacuuming the ants or wiping them up with soapy water clears what you can see tonight and removes their scent trail, but the nest sends more tomorrow. The fastest real result comes from putting bait out today and letting the trail work, because bait is the only thing that reaches the ants you cannot see.
The two can live together if you are careful about where. Clear the ants that have reached the food or the bench, and leave the line that leads to the bait, so that the workers still on it can carry it home.
What scent keeps ants away?
None for long. Vinegar, peppermint, citrus and cinnamon break or mask the scent trail for a while, and the ants lay a new one from the same nest. None of them reaches the colony, and with Argentine ants anything that genuinely repels them can make the nest split and move, which spreads the problem rather than ending it.
That does not make them useless: wiping a bench with vinegar or soapy water is a perfectly good way to clean up after a bait has done its job. We have looked at each of them in natural ant remedies, tested against what they claim.
When to stop doing it yourself
Call someone when ants are coming out of the walls in more than one room, when two weeks of bait has made no difference to the numbers, when Argentine ants keep coming back from the neighbours, when a spray has turned one trail into several, or when a food business or a rental needs a written record of the treatment.
What we add is mostly scale and order. We identify the species, bait inside and out at enough points to reach every nest, find the entry point and tell you what will close it, and deal with the plant that is feeding the colony. You can see what our ant treatment involves and costs, or request a visit and we will look at it with you.
Questions
Questions about ants in the house
Will ants leave if I keep killing them?
No. The ants you kill are foragers, and the nest replaces them, so a trail you keep killing simply keeps coming. Ants leave when three things have happened: the colony has been reduced by a bait the workers carried home, the food or water that drew them has gone, and the gap they used to get in has been sealed.
Is my house dirty if I have ants?
No. Spotless houses get ants too, because ants come in for water and anything sweet, and in summer for protein to feed their brood. Keeping benches clean and food sealed shortens an ant problem and makes a bait more attractive by comparison, but tidiness on its own neither causes ants nor keeps them out.
Should I kill ants if they are in my house?
Deal with the colony rather than the individual ants. If they are indoors, bait them, because a bait is what reaches the nest, while killing ants one by one only removes foragers. Ants that stay outside can be left alone, and University of California guidance points out that in the garden they feed on other pests.
How long does it take to get rid of ants in the house?
Expect fewer ants within about 5 to 10 days of baiting and several weeks to finish, and longer for Argentine ants and white-footed house ants. Numbers usually rise for the first few days as the workers recruit to the bait, which is a sign it is being taken rather than a sign it has failed.
How do I get rid of ants in my car?
Clear out every crumb and wrapper, vacuum the seats and footwells, and look at where you park: a car left under a tree the ants are farming, or over a trail, keeps getting re-colonised. Do not spray the cabin. Argentine ants travel in vehicles, so do not drive a car with ants in it to the bach or into someone else's garden until it is clear.
Can I get rid of ants permanently?
For most species, yes, as far as the house goes: bait the colony, remove the honeydew source outside, seal the entry point, and they stay gone until a new colony moves in. Argentine ants are the exception, because a supercolony refills a cleared house from the properties around it, so with them the realistic aim is a house kept clear.
Sources
- UC Statewide IPM Program: Ants (Pest Notes)
- UC Statewide IPM Program: Ants in the home, quick tips
- Manaaki Whenua Landcare Research: Argentine ant biology
- Manaaki Whenua Landcare Research: Technomyrmex jocosus (white-footed house ant) factsheet
- Te Ara, the Encyclopedia of New Zealand: Introduced ants
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More advice
Other things worth knowing
Argentine ants in Auckland: how to tell, and what actually works
How to tell Argentine ants from other Auckland ants, why their supercolonies refill a cleared house, when they peak, and what works against them.
Read this AntsDoes ant bait work, and which kind should you use?
Which ant bait suits which ant: gel, liquid, granules and bait stations compared for New Zealand homes, why bait beats spray, and when DIY stops working.
Read this IdentificationTypes of ants in New Zealand, and how to tell which one you have
The ants in New Zealand homes and gardens by size, colour, smell and trail, which ones bite, why white ants are really termites, and what to do about fire ants.
Read thisNot sure what you are dealing with?
Describe it, or send a photograph. Identifying it correctly is our job, and it is what decides the treatment.