I use this bait.
Terro*Liquid Ant Baits | Walgreens
You can get it at Walgreens plus many other stores. I bought mine at Lowes.
Put it where you see them, they will swarm to it and take back to the colony. Works great. Be careful, as it is a liquid and will spill out if you turn up on its end.
I picked up a lot of ants in a campground and used this to get rid of them quickly. I usually just leave it where I found the ant problem and throw away after about a month.
I have also used these in my home. Keep away from your pets.
A lot of ants are after water... Good luck