Ants — Identification, Treatment & Removal

Ants are among the most common household pests in the UK, with black garden ants and pharaoh ants frequently invading kitchens and food storage areas in large numbers.

Typical Cost

£60–£120

DIY Possible?

For mild cases

Season

Ant activity in the UK is strongly seasonal

Overview

The black garden ant (Lasius niger) is by far the most common ant pest in UK homes, entering buildings in search of sweet foods during spring and summer. Pharaoh ants (Monomorium pharaonis) are a more serious indoor pest, particularly in heated buildings such as hospitals and blocks of flats, and require specialist treatment. While ants are not typically a health hazard, large infestations can contaminate food, undermine paving, and cause considerable nuisance.

Signs of a Ants Infestation

  • Trails of ants marching in a line between a food source and their nest, often seen along skirting boards, worktops, and window sills
  • Small piles of fine earth or sand around paving slabs, at the base of walls, or in cracks in paths — these are excavated nest material
  • Ants swarming indoors, particularly flying ants during "flying ant day" events in July and August
  • Ants found inside food packaging, around pet food bowls, or in bin areas
  • Rustling sounds in wall cavities or beneath flooring in cases of large or established colonies

Health Risks

  • Contamination of food and food preparation surfaces, as ants traverse both outdoor and indoor environments carrying bacteria on their bodies
  • Pharaoh ants in particular are associated with the spread of pathogens including Salmonella, Staphylococcus, and Clostridium, especially in hospital settings
  • Some ant species can bite, though UK species rarely cause more than minor irritation
  • Structural nuisance from nesting activity undermining patios, paths, and lawns

DIY Treatment Methods

Ant bait stations

High effectiveness

Ready-to-use bait stations containing a sweet liquid insecticide that worker ants carry back to the nest, poisoning the queen and the entire colony. Place stations along ant trails and near entry points. Allow up to two weeks for the bait to be distributed throughout the colony.

Boiling water on nests

Low effectiveness

Pouring several kettles of boiling water directly into an outdoor ant nest entrance. This can kill a significant number of ants and may destroy a small nest, but larger colonies often extend too deep for the water to reach the queen and brood chambers.

Ant powder (insecticidal dust)

Medium effectiveness

Applying permethrin-based ant killer powder along ant trails, around entry points, and directly onto visible nests. Worker ants walk through the powder and transfer it to the nest. Effective for garden ants but must be kept dry to remain active.

Sealing entry points

Medium effectiveness

Using silicone sealant or caulk to block gaps around doors, windows, pipes, and cracks in walls where ants are entering the property. This does not address the nest itself but prevents ants from gaining access to your kitchen and food areas.

Removing food attractants

Medium effectiveness

Thoroughly cleaning kitchen surfaces, storing food in sealed containers, wiping up spills immediately, and keeping bins clean and closed. Removing the food source that is attracting ants into the property can encourage them to forage elsewhere.

When to Call a Professional

  • You suspect pharaoh ants, which are small (2mm), yellow-brown ants typically found in heated buildings — these require specialist treatment and cannot be effectively controlled with shop-bought products
  • The ant colony is nesting inside the fabric of the building, such as within wall cavities, under floors, or in insulation, where it cannot be reached with surface treatments
  • Repeated DIY treatments have failed to resolve the problem, suggesting a large or multi-nest colony
  • Ants are infesting a commercial food premises where pest control records and compliance with food hygiene regulations are required

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How Much Does Ants Treatment Cost?

£60–£120

Professional ant treatment costs depend on the species involved and the extent of the infestation. Garden ant treatments are usually straightforward and may require just one or two visits. Pharaoh ant infestations in large or multi-occupancy buildings can be significantly more expensive and time-consuming, potentially requiring a coordinated treatment programme across multiple units.

Prevention Tips

  • Keep kitchen worktops and floors scrupulously clean, wiping up crumbs and sticky residues promptly
  • Store sugar, honey, jam, and other sweet foods in sealed containers rather than leaving them in open cupboards
  • Rinse out food tins and jars before placing them in recycling bins
  • Seal gaps around doors, windows, and where pipes enter the building using silicone sealant
  • Clear vegetation and debris away from the base of external walls to discourage nesting close to the property
  • Empty and clean pet food bowls after feeding rather than leaving food down throughout the day

Seasonal Information

Ant activity in the UK is strongly seasonal. Colonies become active in spring (March–April) as temperatures rise, and foraging workers increasingly enter buildings from May through September. The famous "flying ant day" events typically occur in July or August, when winged males and queens swarm to mate — though swarming may happen over several days or weeks depending on weather conditions. Ant activity drops significantly from October onward, and colonies become dormant through winter.

Frequently Asked Questions

What is flying ant day?

Flying ant day refers to the period, usually in July or August, when virgin queen ants and males take flight to mate. It is not a single nationwide event — swarming is triggered by warm, humid conditions following rain and can occur on different days in different areas. The swarms are harmless and typically last only a day or two.

Why are ants coming into my kitchen?

Ants send out scout workers to search for food, and when a scout finds a reliable source, it lays a chemical (pheromone) trail back to the nest for other workers to follow. Sweet and sugary foods are particularly attractive to the common black garden ant. Cleaning the trail with soapy water and removing the food source will discourage further visits.

Are UK ants dangerous?

The common black garden ant does not sting and its bite is too weak to pierce human skin, so it poses no direct health risk. However, pharaoh ants (found mainly in heated buildings) can carry harmful bacteria. The main concern with garden ants is food contamination and the nuisance of large numbers in the home.

How do I get rid of ants permanently?

The only way to permanently resolve an ant problem is to destroy the queen in the nest. Bait-based treatments are the most effective approach because workers carry the bait back to the colony. Killing surface ants with spray only removes a fraction of the colony and the queen will quickly replenish worker numbers.

Can ants damage my house?

Garden ants do not cause structural damage to buildings in the UK, unlike carpenter ants found in other countries. However, nesting activity can undermine paving slabs, damage lawns, and push fine soil into properties through small gaps. In rare cases, ants nesting near electrical connections can cause short circuits.

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