I like this idea. I'll add it to my list.I had a yard that was half fire ant hill because there were a lot of fruit trees. I used the "erupting volcano" recipe from the kids science fairs. Sprinkle the ant hill liberally with baking soda and then pour concentrated white vinegar (from Home Depot, etc not food grade) on it. The resulting foam is acidic and follows their tunnels into the nest itself and kills them. Then water heavily to disperse the residue when it is done. Didn't have tortoises at the time but was safe for dogs and cats.