Yeah, the ants. Maybe they just followed a scent trail into your house and live far away. If that’s the case then it’ll be easy. A couple of addresses ago we had a fire ant colony living under our foundation. Nothing we did got rid of them. Even powerful poisons that they take back to the colony only worked for a week or two until the next round hatched and they were right back. It sucked! Best of luck! Hopefully they live far away.