Spray the tree and soil with Miathlon at prescribed dosage, repeat after 3 days. During a dry spell "ant be gone" is a goo that ants like (place it near the pot on the shelf), they take it back to the nest and feed the younguns, which in turn kills the colony.
Modern medicine treats the problem, Chinese medicine treats the source.
I kept chasing my tail with my trees. I'd get rid of them, only to have them return. Now each spring I spray the entire lawn with Miathlon as prescribed, I repeat the application a week later. That normally takes care of it. Should activity re-surface, I re-apply. They do sell ant spray (read diluted) for lawns, at about 5 times the price.
The benefit of my early/yearly intervention, not only no ants around my trees but none in the house. I have also found that those pesky little household ant traps aren't worth a damn.