The Ortho products mentioned and the advice are excellent here. I fought ants for years at a home with a very wooded lot.

One thing to be very watchful of is those large black ants. If you see them, you must give them an all-out attack, because those things eat their way into oak trees and kill them, or at the least weaken them severely.

I've seen this repeatedly, and I saw an oak tree with a 10" trunk break off near the base in a big windstorm once, and it revealed that the inside had been hollowed out by those ants.

They also seem to like to live inside railroad ties, so keep an eye on those.