Cutting torch. Set oxy/ acetylene, don't light. Stick tip in hole for 10 seconds,+/_. Then light torch and stict flame to hole. The ground for about a 10' circle will actually lift just a tad. Concussion will kill every last one. Don't get carried away with the gas mix. Heck, 5 seconds probably is enough. As with reloading, check to make sure this load is safe in your ant bed, it is safe in mine. I can't guarantee yours.
Pee on Photobucket