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Ants In The Kitchen
A trail of small black ants across the worktop or in from under the back door, every day in summer.
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What's happening?
A trail of ants indoors is a foraging line from a nest that is almost always outside — under a patio slab, in a cavity wall, beneath a doorstep or in the garden. The workers you kill on the surface are a fraction of the colony, and the queen is untouched, which is why spraying the trail gives a day of relief and then the trail returns. The species matters. Garden black ants are a summer nuisance with an outdoor nest, and bait taken back to the colony resolves them. Pharaoh's ants are a different problem entirely: tiny, yellowish, they nest inside heated buildings, spread through blocks of flats, and split into new colonies when sprayed — so an amateur insecticide multiplies them rather than reducing them.
What usually causes it?
- A garden black ant nest under a patio slab, path, doorstep or in the soil against the wall
- A cavity wall or floor void nest reached through an air brick or a gap at the threshold
- Sugary residue on worktops, in bin lids, under a toaster or behind a kettle
- Pet food bowls left down, and spilled honey, jam or syrup in a cupboard
- Gaps at the threshold, around pipework, or where a conservatory or extension meets the house
- A winged swarm on a warm, humid day — nuptial flight, which is the colony reproducing, not invading
- Pharaoh's ants nesting inside a heated building and spreading through service voids in a block
Is it dangerous?
Garden ants are a nuisance rather than a hazard: they do not sting meaningfully and carry little disease risk, though they contaminate exposed food. Pharaoh's ants are treated more seriously in the UK because they can carry organisms of concern and are a recognised problem in hospitals and blocks of flats. The main practical warning is procedural rather than medical — never spray ants you have not identified, because the wrong species plus the wrong product turns one colony into several.
Can I fix it myself?
Yes, for garden black ants. Find and follow the trail to the entry point, then remove the food: clean the worktops and behind appliances, keep the bin closed, seal sugary foods, and pick up pet bowls. Use a sugar-based ant bait rather than a spray, and leave the trail alone while they carry it back — killing the workers stops the bait reaching the queen. Seal the entry gap once traffic stops. Do not use boiling water or petrol on a nest, and if the ants are tiny and yellowish rather than black, stop and get them identified.
When should you call a pest controller?
Call a pest controller if bait has not worked over a couple of weeks, if the nest is inside a wall or floor void, if you are in a flat where the problem is shared, or if the ants are small and pale rather than the familiar garden black ant — Pharaoh's ants need a specific baiting programme and must not be sprayed. Also call where a swarm of winged ants keeps emerging from inside the building, which suggests an internal nest rather than a garden one.
What will the pest controller actually do?
- Identify the species, because garden ants and Pharaoh's ants need completely different treatment
- Trace the trail to the nest, including cavity walls, floor voids and under hard landscaping
- Place appropriate baits so workers carry the active ingredient back to the queen and brood
- Avoid repellent sprays where they would cause a colony to bud into several
- Proof entry points at thresholds, pipework and air bricks once activity has stopped
- Advise the managing agent where a block-wide Pharaoh's ant programme is needed
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