I use a boric acid-based liquid: Ant-Kil by Protexall, & I think Harris' makes 1 as well. It comes in a little bottle & you drip a few drops near the ant trails, they flock to it & soon they're all gone. Alternately, you can put some in a bottle cap, rather than directly on surfaces. Our house has tiled windowsills, so I just dribble a bit right on the tile.

I think I got mine @ the hardware store, & I think some groceries like Publix may have it too.

I like it because boric acid is something they can't develop resistance to & it basically non-toxic to humans & pets

HTH

Here is a link that might be useful: Crazy ant info @ IFAS

Actually boric acid is quite toxic to pets, so please be careful about where you put it if you have pets. It's harmless when used topically, but if they ingest it (and most baits have some kind of yummy base to get the ants to eat it), it can cause real trouble.

From the national pesticide information center:

Signs of Toxicity - Animals

Ingestion of small amounts of boric acid or borate salts by animals has resulted in clinical signs that include excessive salivation, thirst, fever, vomiting, retching, depression, loss of appetite, diarrhea, and abdominal pain.

More here:

Here is a link that might be useful: boric acid fact sheet

Sorry - guess that should've just been 'humans'. Our cats have never been remotely interested in the stuff, thankfully....