Photograph depicting a common black ant

Pest Control – Common Black Ant

Background Information

While there are many species of native ant in the UK, the common black ant (or garden ant) is the only species likely to enter dwellings, where it can become a serious pest. The worker ants forage for food and are attracted to sweet food items, and will sometimes go to great lengths to reach them. If, when foraging, an ant discovers a source of sweet food within your house, it will communicate this to the other foraging ants and will invade in quite large numbers. In this instance, it is important that all food is kept in sealed containers and counters and floors are kept clean from even the smallest spills.

Common Black Ant – Key Facts


Workers are 2-3mm, black/dark brown in colour with a large head and characteristic ‘waist’


Trails of worker ants can often be seen around the internal perimeters of your home, near external doors and kitchens


The queen tends to the first brood of sterile female workers. The workers then look after the queen and new larvae, enlarge the nest, forage for food and bring this to the nest.


Once the colony is large enough new queens and winged males swarm to mate. This usually occurs in late summer and lasts a few days at most. The males die and a small % of the mated queens survive to the following spring to start new colonies

Control & Treatment

Treatment consists of 1-2 visits spaced 2 weeks apart.
We will use a combination of a residual insecticidal spray and gel-based bait. The spray will be applied directly to the nest if accessible and will kill any ants that come into contact with it. The gel baits are placed internally in containers around the areas where the workers are foraging. The aim is to kill the queen and stop her from producing more workers – the workers eat the gel but it doesn’t kill them immediately, giving them time to take some back to the nest to feed to the queen.
One visit is usually enough to treat for common ants, therefore we carry out one visit as normal treatment. If ants are still bring seen after 14 days then another chargeable visits can be carried out.
If a nest is discovered early and the queen can be killed before the mating swarm then this can help reduce the likelihood on annual issues. It can take several years before a colony is fully grown and the mating swarms begin (see fact box for more information). Colonies can be formed in close proximity to each other; if they join up then one queen will assume dominance and kill the others.

Important Information

The insecticide we use is residual. This means an active film of the insecticide remains active for up to 2 weeks to prevent the need for frequent reapplication. Therefore it is important not to wash the treated areas until just before the 2nd visit is due.

Further Advice

Proofing – Ants can get through holes as wide as 1mm. Thus it is important to seal all entry points, using mastic or other approved fillers.
Housekeeping – Ensure all food and drinks are cleaned up, all food is kept covered, this will help prevent ants being attracted to the property.

Download our Common Black Ant Information Sheet

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If you have problems with common black ants…