So I've tried just about every method mentioned except for flaming gasoline with mixed results. Toxic spray (doesn't work if you can't soak the nest), drowning them by running a hose (my soil is too sandy), piles of ice cubes on the entrance (they melt), piled up soil (they can dig around) So I ended up trying something new: jamming a dozen mothballs in the entrance hole and letting them roll down into the nest. before trying this, the nest was very active, I was counting one takeoff/landing every second or two. After a few days of moth balls, it's down to one takeoff/landing every 10-15 seconds. Gonna keep an eye on things and see how this goes.