Ants live in colonies in underground nests. It is difficult to find the nest, but if you do so it is best to leave it undisturbed. If you try to break it up you will only disperse the ants, who will go off and create new nesting sites. Ants gain access to a house through cracks and crevices, usually in the floor, and once inside they will forage for food. They will spend most of the summer taking this back to the nest to feed the colony. In late summer, you will see the ants flying off to set up new nests.

The best way to get rid of ants is to hire a professional to treat the problem with a spray, which is applied to the downstairs rooms. The spray is designed to give the ants sufficient time to get into the house and return to the nest, taking some of the spray with them on their bodies and subsequently infecting the whole colony. As ant colonies grow over the summer, it is advisable to have the treatment carried out as soon as you see one in the house. The longer you leave it, the more ants there will be. If you are dealing with one particularly large nest, or several, you may need more than one treatment. While the spray is effective for four to six weeks, you should keep an eye out for ants two weeks after the treatment has been carried out.

A health risk assessment should be conducted before any chemical treatment is carried out, and crawling children and animals should not be allowed into the rooms for at least two hours after the spray has been applied.

Bob Lynch is proprietor of Aardvark Pest Control, Dublin

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