Finally Got Rid of Ants Under the House (No Access!)

After a year of battling ants crawling under my house and in to my kitchen, bin sofa, I’m finally happy to say they’re gone. No under-floor access, no easy spray routes — just persistence, the right bait, and a few clever tricks.

This post may contain affiliate links, which means I’ll receive a commission if you purchase through my link, at no extra cost to you. Please read full disclosure here.

Ant Baits Available in New Zealand

Here are the main ant bait products you’ll find at Mitre 10 and other NZ hardware stores:

• Extern Ant Killer (blue liquid) — this is what finally worked for me
• No Pest Ant Bait — gel in a tube, but dried out too quickly for my liking
• Kiwicare Ant Bait — the stations themselves were good, but the bait didn’t attract them much
• Terro Ant Killer — widely available, liquid gel formula
• EcoAnt — a more natural option, though slower acting

Why My Previous Attempts Failed

The biggest issue I had was the bait drying out. The No Pest gel and Kiwicare stations both dried too quickly in the warm, dry space under my house. Once the bait dried, the ants lost interest and moved on. Using cardboard made things worse — they absorbed moisture and dried the bait out even faster.

What Actually Worked

The game-changer was switching to Extern Ant Killer (that blue liquid in the little bottle from Mitre 10) and putting it in plastic containers instead of cardboard. Specifically, I used milk bottle lids (or any small plastic lids) cut down to size.

The key design features:

• Plastic so the bait doesn’t dry out
• A small edge around the rim so the bait doesn’t drip off the side
• Ants can still climb onto the lid and access the bait

The Step-by-Step Process

This routine made all the difference:

1. Put down a generous amount of bait — about half-fill the bottom of a milk bottle lid
2. Watch the ants swarm — they’ll find it quickly and start taking it back to the colony
3. They might seem to go away — don’t be fooled
4. Put down another milk lid with the same amount in the same area
5. The next wave of ants will come — keep replacing bait as new ants arrive
6. Repeat until no ants show for over a week — this took me about 2 weeks putting down new bait every few days (same big amount each time not drops)
7. Leave some bait down just in case — I still have a few stations out, but honestly, I haven’t seen ants in ages

The secret is putting down loads of bait and replacing it consistently. Ant colonies are huge and resilient — you need to keep the supply going until the colony collapses.

More tips: Make sure to keep your bins empty and kitchens clean to avoid giving other foods sources to the ants. Any left over food make sure it’s sealed in very tightly closed pots. Food items like honey and peanut butter might need to be stored in the fridge as they love them.

Deterrent Tip: Peppermint Essential Oil

Peppermint essential oil seemed to work best at deterring ants from entering certain areas. Just don’t put it around your bait — it will repel the ants from the bait too and defeat the purpose.

For areas like my sofa, I made a spray with this mixture:

• 10–15 drops of peppermint essential oil
• 1 cup of water
• A few drops of washing-up liquid (helps the oil mix with the water)

Shake well before each use and spray around entry points, under furniture, and along skirting boards. The ants don’t like the smell and tend to avoid treated areas.

Summary

The combination of the right bait (Extern Ant Killer), the right container (plastic milk bottle lids), consistent replacement, the right amount, and peppermint oil as a deterrent did the trick. It took patience and a bit of trial and error, but it’s worth it.

If you don’t have access to Extern Ant Killer, I think the difference is it’s a borax bait with pheromones.

I’m not an expert on types of ants, I thought I had white footed ants hence why I thought for a year baits didn’t work, as they supposedly don’t regurgitate food. Most likely I had Argentine ants hence why there were so many and why I needed to use enough bait to get to all the ants.

If you’re in the same boat — no under-floor access and ants everywhere — start with the Extern Ant Killer, use plastic lids, and keep replacing the bait until the ants stop coming. Good luck!