Ants are among the most commonly reported pest problems in UK homes during warmer months. For the majority of properties, the species responsible is the black garden ant — a nuisance that responds well to basic hygiene measures and readily available DIY products. For a smaller number of properties, particularly those in shared or heated buildings, the culprit may be the Pharaoh ant, which is a genuine health risk requiring immediate professional intervention. The first step in any response is identifying which species is present, because the treatment approaches are not interchangeable and a wrong response to Pharaoh ants can make the infestation significantly worse.
Garden Ants and Pharaoh Ants: Key Differences
Garden ants, often called black ants, nest in garden soil, under paving, or beneath floors. They are attracted to sweet food residues and typically enter properties in trails moving toward food sources. Once a year, usually in summer, winged males and queens emerge in a mating swarm that can look alarming but is a natural process lasting around forty-eight hours. Garden ants carry no significant health risk and are manageable with standard DIY pest control.
Pharaoh ants are a different situation. They are small (approximately two millimetres) and pale yellow or brown, which makes them easy to overlook initially. They are found only indoors, preferring warm, humid environments near heating systems, boilers, and sinks. Unlike garden ants, they do not nest in soil; they nest within building fabric, often deep within wall cavities or under floor insulation. They contaminate food and water and are capable of spreading pathogenic bacteria, making them a health hazard rather than a nuisance. They are particularly problematic in blocks of flats and multi-occupancy buildings, where they can move between units through service runs and pipework voids.
Do not attempt to treat a Pharaoh ant infestation using DIY aerosol sprays. Doing so disrupts the colony without eliminating it, causing it to fragment and establish multiple new nests across the property. This splits the problem rather than solving it and makes professional eradication significantly more difficult.
Preventing Garden Ant Problems
Garden ant activity is closely linked to food availability and entry points in the building fabric. Sealing gaps around doors, windows, and utility penetrations removes the routes ants use to enter the property. Prompt cleaning of food spillages and storing food in sealed containers removes the reward that brings them in. Kitchen bins should be emptied and cleaned regularly, as residue in the bin liner is a sufficient food source to sustain foraging activity.
These measures apply at both the start and during a tenancy. When ants are first noticed, addressing food hygiene and sealing visible entry points often resolves the issue before it develops into a larger problem.
Treating a Garden Ant Infestation
Where a garden ant problem has established despite basic hygiene measures, DIY treatment is appropriate. Insecticide aerosols can be applied into cracks, crevices, skirting board gaps, and around air bricks. Insecticide dusts applied directly to nest entrances, particularly outdoors around door thresholds and paving, typically provide several weeks of control. All insecticide products should be used strictly in accordance with the manufacturer's instructions, and surfaces in contact with food preparation should not be treated without confirming product suitability.
For persistent problems that do not respond to DIY products, or for confirmed or suspected Pharaoh ant infestations, professional pest control is the appropriate route. A BPCA-certified technician can confirm the species and apply the correct treatment method — for Pharaoh ants, this typically involves slow-acting gel baits that the ants carry back to the colony rather than spray treatments that would cause fragmentation.
Useful Resources
BPCA Pest Awareness: Ants
Professional identification guide for Garden, Pharaoh, and Ghost ants from the British Pest Control Association.
Find a Professional Pest Controller
Search the national database for BPCA-certified technicians in your specific postcode.
Safe Use of Biocides
Health and Safety Executive guide on the legal and safe use of pesticides in domestic environments.
This article reflects our understanding of the law at the time of publication. It is for general guidance only and does not constitute legal advice. Always verify against GOV.UK or seek qualified legal advice before acting.
