Take cinnamon, sprinkle ever so lightly where ants like to come in, even outside. They will not cross the cinnamon line!
I tried this in my kitchen recently because the sugar ants were starting to show up on my countertops. I scattered cinnamon behind my sink, which is where they seem to get into the house. I haven't seen an ant in days! I even left a box of donuts on the counter and they have been left entirely alone. Seems much safer than using ant poison or boric acid in my kitchen.
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Spread some ground cinnamon where you think the ants are coming into the house.
