Try Amdro. We got it at Lowes or Home Depot. Last summer we had tiny black ants crawling on the kitchen counter, and didn"t see any trail. I finally saw an ant crawl out of a tiny space along the edge of the window and molding( where you might put csaulking). Anyway, this stuff has a tiny nozzle and you put it right into or next to the space. NO MORE ANTS!! It can also be used outside. What we discovered later on, we had flower beds around the house that were filled with mulch. Try turning over the mulch, you will see thousands of ants! Now my beds next to the house are rocks!