Paul,
We live on the edge of the woods so lots of trees and black ants that
used to get into the house. Looking for a solution to that problem we
purchased KM Ant Pro Bait Station(s) and filled them with Gourmet
Liquid Ant Bait. The ants find this food source and bring the
contents back to the nests. Took a couple of months but since then
for several years now all we do is purchase the liquid and refill the
containers and we're good for another season.
Not cheap but solved our problem. Good luck.