I've had good luck with Tengard. I just mix it to label specs in a pump up sprayer, then push the wand as deep as I can in the nest and slowly pull it out with the nozzle still open. Then I soak the top of the mound itself. Thousands of dead ants almost instantly, and the ants escaping the mound die when they crawl through it. It 's not unusual for the mounds to be solid black with dead ants by the next morning. Tengard's active ingredient is Permethrin, and we use it around the foundation of the house for ants, crickets, etc..

AL