Advice
How to get rid of ants in the house and keep them out
To get rid of ants in the house, follow the trail to where they come in, clear away the food and put an ant bait on the trail: the workers carry the bait back to the nest and share it there. Leave the trail alone while the bait works, and give it weeks rather than days. A spray only kills the ants it hits; the nest, usually outside under paving or in a wall, carries on.
In this article
Key facts
- The ants you see are workers. Their nest is usually outside, under patio slabs, in the lawn or in a cavity wall.
- In Britain the most common ant is the black garden ant (Lasius niger): nearly 90 % of the flying ants reported in the Royal Society of Biology's Flying Ant Survey were this species.
- Choose one route: a few stray ants you keep out, a trail that comes back every day you tackle through the nest.
- Leave the trail alone while a bait is down. That scent trail leads the workers to the bait.
- A spray is for the single ant you can see, not for the nest.
Why are ants suddenly coming into my house?
Ants suddenly come into your house because a scout has found food and laid a scent trail to it, and the rest of the workers now follow that trail from the nest to your kitchen. It usually starts in spring and summer, when the nest is active again and the workers need food for the queen and the larvae. One ant on the worktop is a scout, not yet an infestation. A line of ants walking to the same spot every day means a nest has found a food source in your home, and it will keep coming back until you deal with it. Outside, ants do little harm, so in the garden you can usually leave them be.
How do you get rid of ants in the house?
To get rid of ants in the house, pick the right approach first: keep a few stray scouts out, but tackle a trail that comes back every day through the nest, with a bait. This is how you deal with an ant trail:
- Follow the trail to the gap, threshold or skirting board where the ants come in, or to the nest.
- Clear away the food. Wipe up crumbs and sticky spills and keep sugar, honey, syrup and pet food in containers that close tightly.
- Put an ant bait on the trail or right next to the nest entrance, as many as the label says for the area.
- Leave the trail alone. No cleaning, no spraying, no vinegar or strong smells on it. That route brings the workers to the bait.
- Wait as long as the label says and check every week whether ants are still walking. If a second trail appears, put a bait on that one too.
- Then seal the gaps and wash the trail with warm soapy water, so new scouts cannot follow it.
| What do you see? | Approach | What do you do? |
|---|---|---|
| A few stray ants, no fixed route | Keep them out | Clear food away, wash the spot, seal gaps |
| A trail that comes back every day | Tackle the nest | Bait on the trail, leave the trail alone, wait weeks rather than days |
| One ant you see right now | Remove it straight away | Vacuum it up or put it outside |
Do not combine the two routes: wiping the trail or putting a strong smell on it sends the workers away from the bait.
How do you find where ants are coming from?
Follow the trail backwards, away from the food, to the gap where the ants disappear: a crack along the skirting board, the threshold of the back door, a gap around a pipe or the edge of the patio. Ants need only a tiny gap to get in. If you cannot find the nest itself, it is often inside a wall, under the floor or outside under the paving. That does not matter: put the bait on the trail where the ants come in, and the workers will find their own way back to the nest.
Why does a bait reach the nest when a spray does not?
A bait reaches the nest because ants share their food: a worker that feeds on the bait carries it back to the nest and passes it on, mouth to mouth, to other workers, the larvae and the queen. This passing on of food is called trophallaxis. A spray only kills the ants it touches, while the queen in the nest keeps laying eggs and new workers keep coming.
| Contact spray | Ant bait | |
|---|---|---|
| What does it reach? | The ant it hits | The workers, and through them the nest |
| How fast? | Straight away for that one ant | Slowly on purpose, so the workers can carry it home |
| The trail | Do not spray the trail | Leave it alone |
| Meant for | A single ant you can see | A trail that keeps coming back |
Read more about the difference in insecticide or trap: which works better.
How do ant bait stations work, and how do you use one?
An ant bait station is a closed box with a bait that ants take as food: a worker walks in, eats, carries a portion back to the nest and shares it there. It only works if the ants find it, so placing it is everything:
- Put it on the trail itself, not beside it: against the skirting board, by the back door or where the ants come in.
- Leave the trail alone and do not spray anywhere near the station.
- Keep it away from food, children and pets, and do not open it.
- Leave it in place for as long as the label says and check it every week.
Before you buy one, read the label: which active substance it contains, which ants it is meant for, whether it may be used outside, how many you need per room and how long it should stay down.
Use biocides safely. Always read the label and product information before use.
How long does it take to get rid of ants?
Getting rid of ants usually takes weeks rather than days, because a bait has to travel through the whole nest. As an example, the label of an ant bait with spinosad says it works 3 days after an ant has eaten it, that it should stay in place for at least 3 weeks and that you check it every week. Follow the label of the bait you use.
| When | What happens | What you do |
|---|---|---|
| Day 0 | You put the bait on the trail | Leave the trail alone, spray nothing |
| First days | Workers carry the bait to the nest | Leave it in place |
| Every week | You see whether ants are still walking | Check; put a bait on any second trail |
| End of the treatment on the label | No more ants on the trail | Remove the baits, seal the gaps, wash the trail |
Can you use ant baits outside?
You can use ant baits outside only where the label allows it. Some baits may be used outdoors around buildings, such as on a patio, but only in a spot that stays dry and is sheltered from rain and cleaning water. Keep baits out of reach of children, pets and bees. In the garden itself you can usually leave ants alone; deal with the nest whose trail leads into the house.
Which ants do you find in UK homes?
Most often the black garden ant (Lasius niger): a dark brown to black ant of 3 to 5 mm that nests under paving and in lawns and comes indoors in search of food. A few other species need a different approach.
| Ant | How to recognise it | Where the nest is | What to do |
|---|---|---|---|
| Black garden ant (Lasius niger) | 3 to 5 mm, dark brown to black | Outside, under paving, in the lawn or in a wall | Bait on the trail; leave the trail alone |
| Red ant (Myrmica rubra) | Reddish brown; can sting | Mostly outside, in the garden and lawn | Leave it alone in the garden; keep it out of the house |
| Pharaoh ant | Very small, pale yellow to light brown | Indoors, in warm, heated buildings | Call a pest controller: spraying can make the colony split |
| Flying ants | Winged ants, larger than the workers | The queens and males of an ordinary nest | Usually nothing; they are gone within days |
Not sure which ant you have? Take a close-up photo and show it to a pest controller.
What are flying ants, and when is Flying Ant Day?
Flying ants are the winged queens and males of an ordinary ant nest, which fly out on warm, humid summer days to mate. According to the Natural History Museum this usually happens in July or August. The Royal Society of Biology's survey found that Flying Ant Day is not one day: flying ants appear on many days across the summer, with peaks that each last a few days. How to recognise them, tell them apart from termites and what to do is in flying ants in the UK.
What should you do first about ants in the kitchen?
Take away what they come for and find where they come in. Wipe the worktop, clean up sticky bottles and jars, empty the food caddy and the bin more often in warm weather, and do not leave pet food out. Then follow the trail to the gap they use. Crumbs behind and under the fridge and cooker are a classic food source: see where pests hide in your home.
Do home remedies like vinegar or washing up liquid get rid of ants?
They disturb the scent trail for a while at most; no home remedy reaches the nest. A strong smell such as vinegar or peppermint makes the trail hard to follow, but once the smell fades, scouts lay a new one. We know of no research showing that they get rid of an ant nest. What each remedy does is in home remedies for ants. If you use a bait, keep strong smells off the trail.
How fast do ants multiply?
Ants multiply fast in spring and summer: as soon as it warms up, the queen starts laying eggs again and the colony grows, while in winter the nest is dormant. A black garden ant nest has one queen that lays the eggs, and as long as she lives, new workers keep coming. That is why sweeping away the ants you see does not help: the bait has to reach the queen.
What do ant eggs look like?
Real ant eggs are tiny, white and oval, and they stay deep inside the nest. What most people call ant eggs are the pupae: white to pale yellow capsules that look like grains of rice. Between them you may see the larvae, white, curved grubs without legs. If you find pupae under a paving slab or in a flowerpot, there is a nest there.
How many ants live in a nest?
An ant nest holds far more ants than you see indoors: the ants in your kitchen are only a small part of the colony. How big a nest is depends on the species and on how long it has been there. A trail that comes back every spring often comes from the same nest.
Are ants dangerous, and are red ants in the house bad?
Ants are usually not dangerous: in the house they are mostly a nuisance. Black garden ants do not sting, while red ants (Myrmica rubra) can give a painful sting, but they mostly stay in the garden. Ants can contaminate food, and large nests under a patio or path can make the slabs sink.
How do you keep ants out?
Give them no food and no way in:
- Wipe up crumbs and sweet spills straight away, also under the worktop and around the pet bowl.
- Store sugar, honey, syrup and pet food in containers that close tightly.
- Seal gaps around doors, window frames, skirting boards and pipes; ants need only a tiny gap.
- Empty the bin and the food caddy more often in warm weather.
- Vacuum up a scout or put it outside before a trail forms.
When should you call a pest controller?
Call a pest controller when the ants are pharaoh ants, when the nest is inside the building and you cannot reach the trail, or when ants keep coming back after a full treatment. Pharaoh ants live indoors in heated buildings such as flats and hospitals, and spraying them can make the colony split into new nests, so leave them to a professional.
Read more: Flying ants: what Flying Ant Day is and what to do · Home remedies for ants: do vinegar and washing up liquid work? · Insecticide or trap: what works better against pests at home?
Sources
- Natural History Museum: Flying ant day, when winged ants take their nuptial flight (timing, black garden ant, red ant).
- Royal Society of Biology: Flying Ant Survey (species share, flying ant days across the summer).
- Wikipedia: black garden ant (size, nest, single queen), Myrmica rubra (sting), pharaoh ant (indoor nests, colonies splitting).
- Label of an ant bait with spinosad 0.08 % (PT18): 3 days after feeding, at least 3 weeks, weekly check, outdoor use only in dry, sheltered spots, bees.
