I got them one year while in Fla. I think they may have gotten in by dropping from a tree as I saw no signs on the ground. What worked for me was Boraxo soap. I even had them in the ceiling and had to drill a small hole in the closet so I could spray it into the area using a ear syringe. No more ants. You can also sprinkle some in areas where they will track through it and carry it back to the nest. Also safe to use.