The best ways to get rid of ants in your home

What type of ant is infesting your home?  

It’s important to know what type of ant you’ve got before you try to get rid of them – different types require different control methods.

The most common ant invader of New Zealand homes is the white-footed ant. These come from Indonesia and are black with pale feet (though you’d need a good magnifying glass to see that).  

The other common house invader is the Argentine ant, which is more of a honey-brown colour.  

The coastal brown ant is causing issues in the Auckland region, while the common black ant can also be found scavenging for food in homes.  

We’ll focus on the two main culprits: the white-footed ant and the Argentine ant.  

Paul Chapman has been a pest eradicator for 40 years, initially in his native Lebanon where he took over the family business, and now in Wellington where he runs his own companies, Pestproof Pest Control and The Antman.  

If you can’t be sure which type of ant you have in your home, there’s an easy trick, he said.  

“If you see the trails outside, put your hand on the path of the trail. The white-footed ants will scatter but the Argentine ants will just go over as if there is no obstacle, as if it was a bridge.”  

White-footed ants  

There is a common misconception that all ants live outside in nests and come into your house to get food, Chapman said. But for white-footed ants, the inner walls, ceiling and subfloor of your home are their habitat, and they go outside for food.  

“People go and get spray and spray the trails outside, thinking they are preventing them from entering,” he explained. “But they are actually preventing them from getting food from the garden, so they will instead look for food inside your house.”  

While he doesn’t discourage people from trying to deal with ants themselves, he warns that many people get it wrong.  

“They apply bait in the house. The colonies have two parts – a foraging team that feed outside; they don’t share food. When they eat most over-the-counter baits, they only poison themselves and don’t pass it on to the rest of the colony.  

“The rest of the colony [back at the nest] relies on a supply of unfertilised eggs as their source of food. When the queen notices the number of foraging ants is down, she produces more eggs to compensate for the losses.”  

Ants will also notice a high mortality rate and split the colony around the house to reduce the risk of extermination, Chapman said.  

“You’ll only be successful if you keep using bait religiously inside and outside for about two years.” 

That’s why most professional pest eradicators tend to use different baits and formulations that cause a domino-effect pattern of death in the colony.

Chapman said it’s actually easier for the pest experts if people haven’t given it a half-hearted go already, because this can cause the colony to split up.  

“It’s a bit like spreading a virus in a computer network – you want the network connected for it to work.”  

Nic Bolton, of Combat Pest Control, said in his experience baits are never enough to fully eliminate ants, because white-footed ants learn to avoid them, and the workers stop collecting from them.  

Pest controllers have access to restricted sprays designed to specifically break down ant colonies over time, he said.  

Argentine ants  

Argentine ants are one of the world’s top 10 invasive species, posing a serious threat to New Zealand's biodiversity.

Unlike the white-footed ants, which are black, Argentine ants are a honey-brown colour. And they don’t live in the cavities of the house; they live outside but raid houses for food. They prefer warm, dry, elevated sites in urban and natural areas, often in soil.  

“They are so avid for proteins, they attack bird chicks in their nests,” Chapman said.  

The Department of Conservation (DOC) warns that Argentine ants kill and displace native invertebrates that many indigenous species depend on. They will eat lizards, bird eggs and newly hatched chicks, potentially threatening endangered populations. And they devour the food sources that native fauna rely on.  

However, getting rid of them is a bit easier than with the white-footed species, Chapman reckons.  

“They are so determined to move from one place to another and the chemical we place doesn’t deter them. So, they contaminate themselves and others so well and pass it on to each other.”  

He said for white-footed ants, pest controllers tend to spray around the outside of the house. But for Argentine ants, they go as far as possible towards the property boundary. Eradication works best if the neighbours do it too. 

DOC also warns that eradicating Argentine ants needs to be done properly, because Argentine ants link their nests within super-colonies which can extend hundreds of metres.  

DOC recommends setting out multiple bait stations near established trails, especially along the edges of paths and borders, and refreshing any liquid baits regularly.  

DOC’s technical advisor on threats, Murray Fea, warns that people need to avoid spreading Argentine ants to natural areas such as pest-free areas or off-shore islands.  

“The key thing is to be vigilant and avoid moving goods like potted plants, construction and landscaping materials if they notice ants nesting on or in them.”   

It is also important to check inside kayak and dinghy cavities, as well as camping gear, especially when visiting in and around reserves. 

Bolton has seen his share of Argentine ant super-colonies which spread across multiple properties. Baits can be ineffective depending on their content, he said.  

“As most baits are carbohydrate based, Argentine ants are often not interested in them. As they prefer proteins, they can be found cleaning up things like dead geckos, birds, bugs, et cetera. Argentines are also quite partial to wet cat and dog food.” 

Should you buy ant eradication products?

There are many products sold in supermarkets and hardware stores that promise to get rid of ants. We showed them to our experts and asked what they thought of them.

Bait 

Kiwicare NO Ants Liquid Ant Bait + Kiwicare NO Ants Nest Killer Gel Bait 

Paul Chapman: “Both of these will kill foraging ants but, in my opinion, will not be passed on to the rest of the colony. Products will work well if used outside and inside for a long period of time and the ants stay interested in it.”  

Nic Bolton: “Not a lot of difference between the liquid and the gel. The gel is better at adhering to surfaces, for instance if you were to put it straight on a wall.” 

Rentokil Ant Killer Gel  

Nic Bolton: “I have not used this product myself but have had customers that have used it prior to calling us in. White-footed ants find it attractive, and it does impact their colony significantly. As with all baits, not usually enough to fully control the problem.” 

NoPests Ant Bait

Paul Chapman: “It’s the same version we use but just with a different label. Does much more damage to the ant colonies than all the other products in this list.”  

Nic Bolton: “It's the best available to retail.” 

Sprays 

Kiwicare Insect Guard Ant Control Surface Spray 

Nic Bolton: “The active ingredients in this product will certainly repel ants if used around windows, doors and entry points.” 

Kiwicare NO Ants Barrier Spray 

Paul Chapman: “If you are dealing with white-footed ants, you don’t really want to block them inside the house. This product can temporarily prevent Argentine ants from invading your home. Barrier sprays will work well inside the house to temporarily protect some areas. It will also work very well if directly injected into a nest.” 

Nic Bolton: “I've found the active ingredient, permethrin, is not repellent enough to keep ants out. It will kill them fast when first applied and get varied results for several weeks. One bottle would likely not be enough to effectively create a barrier in your house or around it.”  

Raid Max Ant Killer 

Paul Chapman: “For outdoor use only. Works as a barrier spray, which will work to stop Argentine ants from entering your home, but could block white-footed ants inside your house.” 

Nic Bolton: “This is a popular bait for customers. I see many customers who have used this bait ahead of us treating. Anecdotally, Raid Max makes the ants disappear for weeks, but they always return.” 

Sand  

Kiwicare NO Ants Sand + Mortein Ant Sand 

Paul Chapman: “I believe these may harm other non-targeted insects outdoors the same way it’s likely to harm ants.”  

Nic Bolton: “Can be effective at keeping Argentine ants out of your house. Whilst its active ingredient, bifenthrin, is not considered a repellent, it does kill ants quickly and they will sometimes avoid it. Depending how ant sand is applied, it can trap white-footed ants inside your house. That being said, there will be a noticeable decrease in activity when using ant sand.” 

Bait stations  

Kiwicare NO Ants Bait Station, prefilled with No Ants Gel Bait 

Paul Chapman: “In my experience, ants prefer to access bait that is not contained in bait stations.” 

How to keep your house free of ants 

• Keep your house clean, eliminating easy meals for ants. 
• Keep food, including sugar, in sealed containers. 
• DO NOT use repellent sprays around the outside of your house, especially when dealing with white-footed ants, as this will trap them in the house and they will have no choice but to invade your kitchen. 
• Use bait outside.  
• Treat known entry points and active ants inside with repellent sprays.  
• Be safe and wear protective gear.