Garden ants have long been a problem during spring and summer months. All native British ants are outside dwellers and really only present a problem in and around buildings or in gardens.
Although black ants can eat many types of food, they are particularly attracted to sweet substances. One successful foraging worker is able to communicate the information to her co-workers, with the inevitable result of vast numbers of worker ants invading and, incidentally, contaminating, suitable human foods.
Ants will nest in a whole variety of suitable sites, and mostly these are of no significance to man. However, sandy soil in general, and the sand used to form the base of paved garden paths, and in the foundations of houses, attracts local ants and nests may well be formed in these areas. Again, little trouble is caused unless the foraging worker ants invade buildings. This is highly likely if the nest has been constructed beneath the floor of the house and ants are adept at finding even the smallest settlement and other cracks in the structure; other ants are then "'led" into the building.
Control measures are generally only required where ants are penetrating, or on occasion living in, building structures. In cases of penetration the first approach should be to seal obvious faults in the structure using mortar/cement or mastic, as appropriate. It is usually best initially to support such proofing measures by the application of a residual insecticide band to likely access areas
Many 'household' insecticide aerosols are cleared for use against crawling insects. Their use is likely to offer only short-term relief in view of the relatively low dose of active ingredient likely to be applied, and if a householder is involved in 'DIY' control it would be better to use one of the bendicocarb dust 'puffer packs' (0.5%).
First find the nest entrance - indicated by small piles of earth, or by watching the ants moving back and forth from nest to food.
Dust the insect powder along ant runs and in cracks and crevices where ants congregate, nest entrances should be dusted liberally.