The majority of homeowners with an ant problem simply purchase an ant spray to use on the creatures. Such sprays are available at every supermarket, home center and nursery, and they can work wonders. Some homeowners, however, worry about the effect that spraying toxic pesticides could have on their families and pets. So while toxic sprays are certainly one way to kill ants in your yard, several other ways of killing ants are available that don't require anything toxic to either humans or to pets.
Locate the colony (or hill). This is a hole in the ground out of which the ants come and go. The queen ant lives in this underground kingdom. Once the queen ant is dead, the colony dies.
Purchase a spray can of commercial ant killer. Make certain the nozzle of the spray can is pointed away from you and spray a line of pesticide around the base of your house, creating a line that the ants cannot cross. Do not spray on a windy day or if rain is expected within the next 24 hours.
Spray the remaining pesticide directly on the ant hill where the ants are coming in and out of the ground. Spray the hole directly and the ground surrounding the colony. The ants should be dead within 30 to 60 minutes.
Spread powdered cornmeal into the ant colony and all around it if you choose not to use a commercial spray pesticide. Sprinkle cornmeal around plants to create a barrier for the ants. Ants love to eat cornmeal, but they cannot digest the corn so they quickly die of malnutrition. The ants, in the meantime, will carry cornmeal into the colony for the queen, causing her to die as well. The entire colony will be dead in three to four days.
Mix equal parts of powdered sugar and baking soda well in an old salt shaker or even in a plastic baggie as a third way of killing ants in your yard. Sprinkle this mixture on the ant hill and around plants and your home, making a barrier for the ants. The ants love to eat the sugar, but the baking soda covering the sugar combines with the acids in the ants' bodies to create carbon dioxide gas--causing them to explode. The ants will carry some of the powdered sugar and baking soda to their queen, causing her to die as well.
Check for new ant colonies regularly, as new queens can arrive on your property throughout the summer months. Use the same ingredients for killing the new colonies as you used for killing the first colonies.