I recently got a tip for folks dealing with these voracious ants that consume whole trees. I haven't used it myself but saw this work successfully at a friend's place.

For new plantings, drive a white PVC pipe of a good diameter around the in the hole around where the trunk will grow. You may have heard that tying a plastic bag deters them, but I haven't had luck with that. For established plants you might try slitting a tube of PVC and fitting it around the trunk(s).

I would love to know if people have success with this, or any other method. Poison does not work on this type of ant as they are farming their own food in their nests and will not take poison home.

Thanks for feedback!

Happy gardening! Please try to plant and care for a tree or 2 or 3 somewhere. It really makes a difference.