At certain times of the year, many homes become invaded by thousands of ants looking for food, water and shelter. Some of these ants set up new colonies along the way in the walls of the house, a location difficult to access. To kill the ants in a wall, you need bait that is taken back to the colony to eradicate the queen and the entire colony. A common homemade recipe that is low in toxicity to pets or humans works well for this. It will take several days to see results, but the targeted ant colony should not return.
Mix 1 tbsp of honey or syrup with 1/4 tsp of powdered boric acid. This makes enough bait for one station. Increase the amounts to make as many stations as you need.
Smear the mixture on a piece of 2-inch square cardboard with a butter knife. Place about 1 tbsp onto each piece. Make one station for every 3 feet of active ant trail.
Place the cardboard pieces with the bait mix against walls directly in the middle of an active ant trail. Leave the ant bait for several days. Do not clean up the ants during this time, because you want the ants to feast and take the bait back to the colony in the wall to kill the queen.
Replace the bait as needed. Once the ants are gone, throw out the cardboard pieces and leftover ant bait.
Boric acid can be found in the laundry detergent section of most grocery retailers.
Although boric acid ant bait is not as toxic as other pesticides, careful use is still warranted. Keep the bait out of reach of children and pets by placing it in hard-to-reach locations or preventing access to areas with the bait.