It's available at Home Depot & Loewes. You can get it in little plastic traps or liquid in a bottle (you dispense onto a small piece of cardboard). I have ant issues one time every year, and Tero gets rid of them.
Tero is a poison that the ants eat and then take back to their colony, where it's fed to everyone there. It kills the problem at the source (Raid only kills what you can see). When the Tero is out, you will have a LOT of ants feeding from it. Resist the urge to squeal and vacuum up every one of them ..... it's essential that you get as many of them as possible to take the poison so it gets back to the colony.
Put the traps near the wall where you think they're entering the building, and leave them there until the swarms stop descending. I leave mine behind a TV where my cats can't mess with it. I don't know if Tero is poisonous to pets but I just put it where they aren't tempted to mess with it in the first place.