Ants in your home or garden are hard to get rid of, and they can easily get out of control. Ant poisons are unsafe to use around food or vegetable plants, and a child or pet may be tempted to chew on an ant trap. While eucalyptus oil is not safe to for people or animals to ingest, it doesn't leave behind harmful chemicals that take a long time to break down, and it is relatively safe to use in diluted amounts.
Use eucalyptus oil as an effective ant deterrent to keep ants from coming into your house. Wipe outdoor windowsills, door frames and other holes where the ants are coming in with plain eucalyptus oil, and the ants should stay away because the scent repels them.
Mix one cup of rubbing alcohol with one tablespoon of eucalyptus oil and put the mixture in a spray bottle. Spray a line of ants to kill them. Wipe the ants away, and then wipe along the trail with the oil and alcohol solution. Ants leave scent trails between their nests and food sources, so obliterating the trails will help get rid of the ants.
Mix one tablespoon of eucalyptus oil, one tablespoon of dishwashing liquid and two cups of water to make an aphid spray for your plants. Spraying the aphids won't kill all of them, but ants feed on their sweet secretions and protect young aphids as a food source. The ants will look for another food source if they are repelled by the scent.
Find the ant nest if you can. Boil a handful of eucalyptus leaves in a saucepan of water for several minutes, and then pour the boiling water into the nest. The boiling water should kill the queen, and the scent of the oil should keep other ants from returning to the nest.