What product and/or application have you found effective in treating ants in your cemetery?  If you broadcast pesticide over the entire cemetery, how often?

Because our cemetery is 230 years old and on the federal historic register, I attended a historic preservation conference which had one speaker on the topic of using chemicals in a cemetery with very old stones. He said that we should never use herbicides for weeds or insecticides as they both contain acid which can damage stones. I sympathize with your problem as we have ants of all kinds making it difficult to stand in one spot for very long. We have not treated the area for ants. I did have to break down and carefully spray areas covered in sandspurs as it was almost impossible to walk in those places. One other problem we had for a while was yellow jacket nests under our old walls and stones and in clumps of azaleas. We had no choice but to spray as they were attacking cemetery workers who accidentally got too close. In this case, we could spray in the hole without touching any stonework.

Wildfire fire ant and insect dehydrator. May be available under another name- the active ingredient is pyrethrum (an extract of the chrysanthemum flower)