Your home is a sanctuary -- to you, your family and occasionally to a tribe of ants that discovers the delicious ingredients in your cupboards and trash containers and on your counters. You can kill the ants that have already moved in and repel their cousins that live nearby without using toxic commercial sprays. After you apply the solutions and see that they work, spot-treat to prevent the ants from returning.
Kitchen ants, otherwise known as odorous ants, have a sweet tooth and follow the scent of sweet foods. This type of ant leaves a pheromone trail back to the nest for others to follow. You can kill the ants but if the trail survives, the rest of the family soon will be knocking at the door, plate in hand. The key to removing these ants is to destroy the entire colony by making a bait that they'll carry back to the nest, killing the remainder of the ants.
Mix 1 part borax with 3 parts powdered sugar and put a small amount in a bottle cap.
Place the caps near where you think ants are coming into the house or directly on the counter.
The sugar attracts the ants, and when they carry the mixture back to the colony, the rest of the colony ingests the borax grains, which will kill them.
For a liquid repellent, add water to the borax/sugar mixture and absorb it with a cotton ball. Place the balls at entry points, where ants will digest the sweet, deadly solution.
Don't kill ants going to and from the sugar solution. They must take it back to the colony and share for the treatment to be effective.
Keep a spray bottle of vinegar nearby. When you see ants entering, or just as a precaution, spray the baseboards on exterior walls, countertops and window sills. This repels the ants and destroys the pheromone trail. However, it doesn't kill the ants.
Lemon juice can repel ants. Juice four lemons and add to ½ gallon of water. Squirt any area where you think the ants are entering the house, plus countertops and backsplash bases, entry floors, bathroom cabinets, water pipes and around trash cans, to keep ants away.
The best way to prevent ants from coming into your home is to keep the outdoor entry points clear of puddles and standing water. Store dry goods in sealed plastic bags and keep flour in the freezer. Wipe all jars after using them before returning them to the pantry. Keep a spotless kitchen and check that the pipes under your sinks aren't leaking. Remove the food and water and the ants will go away.
Whether they are pheromone-trailing ants or carpenter ants that live in wooded areas around your home, your goal should be to destroy the colony. Locate the ant hill and pour boiling water on it; that should do the job. Repeat several times if it's a large hill.