Ants are the workforce of nature, cleaning up debris and refuse on the ground. But sometimes ants can be a problem in themselves, especially if their population swells out of proportion or if they are a biting ant species that attack you while you're in your garden. Track down the source of your ant problem and kill them using a standard insecticide available at all garden stores and nurseries.
Locate the ant nest in your garden; killing the ants outside of the nest doesn't treat the core problem. Place a dab of honey or sugar water onto a piece of paper and lay the paper, sweet side facing, in your garden.
Wait for the ants to swarm around the piece of paper. After an hour or two, they will have formed a line that trails back to the nest. Follow this trail. Note that sometimes you will notice several trails leading to several different ant nests that will need to be treated.
Treat the nest with a carbaryl- or pyrethroid-based insecticide formulated for use against ants. Follow the insecticide's label for application guidance; toxicity and range of efficacy varies by product. Liquid insecticides are typically poured directly onto the ant hill, while granular insecticide is scattered in a radius of several feet around the nest. For the latter, scavenging ants carry the bait into the nest, where it is consumed and eradicates the entire population.
Use boiling water as an alternative to insecticides. Boiling water effectively collapses the ant nest and cooks any ants inside, ideally including the resident queen. This option works best on small isolated nests and should not be used near plants; the hot water can damage the vegetation. Repeated treatments are sometimes necessary as the hot water may not reach all areas of the nest.