This guide is about keeping ants out before they arrive. If you already have an active trail indoors and want help identifying the species and deciding on treatment, see our separate guide on ants indoors and why identification matters before treatment.

Why ants come indoors

The species most commonly found in UK homes is the black garden ant, which despite the name is actually very dark brown. According to the British Pest Control Association, it’s the foraging worker ants that invade buildings in search of food — they’re drawn specifically to sweet foodstuffs, which they carry back to the nest to feed the colony’s larvae and queen (BPCA: Ant control and prevention). Understanding that motivation is the basis for effective prevention: remove the food source and the reason to come inside largely disappears.

Prevention outside

• Find and note nest entrances. Ant nests often show as small mounds of fine, loose soil in patios, paving cracks, flower beds or at the base of walls. You don’t need to disturb the nest to reduce the risk — knowing where it is tells you which route ants are likely using to reach the house.
• Keep external bins sealed and rinse out recycling that has held sugary drinks or food, since this is a strong outdoor attractant.
• Clear plant matter and mulch away from the base of exterior walls — dense ground cover close to the building gives ants a sheltered route toward gaps in the brickwork.
• Trim back vegetation that bridges from the garden onto the walls or roofline, which ants (and other insects) will use as a route indoors.

Prevention inside

• Seal gaps around windows, doors, skirting boards and utility pipework. Worker ants are small enough to exploit gaps that wouldn’t concern most other pests, so this proofing work needs to be more thorough than a general draught-proofing pass.
• Store food in sealed, airtight containers rather than in packaging that can be reopened — this applies especially to sugar, honey, jam, cereal and pet food, all common ant attractants.
• Wipe up spills immediately, particularly anything sugary, and don’t leave washing-up or pet food bowls out overnight.
• Take note of the trail direction if you do see ants indoors before treating anything — it tells you roughly where they’re entering, which is useful information even if you decide to call a professional rather than treat it yourself.

When prevention isn’t enough

An established outdoor nest very close to the house, or repeated indoor trails despite proofing and food-storage changes, is usually a sign that prevention alone won’t resolve it. The BPCA’s own guidance for the public is to use a professional pest controller for pest problems generally, on the basis that it increases the likelihood of successful treatment and reduces the risk of making the problem worse through an incomplete DIY attempt. Our guide on DIY pest prevention versus calling a professional sets out the signs that point toward bringing in a pest controller rather than continuing to manage it yourself.

Sources and further reading

• British Pest Control Association (BPCA) — Ant control and prevention advice
• GOV.UK — Pest control on your property

Best Pest Control Quotes is an independent guide. We may earn a fee from some links; this never affects what we write.