Here's how Alex Silber of Papaya Tree nursery does it.

Here is a link that might be useful: Ant Control w/Tanglefoot video

Thanks, good video.

They're in California -- Has anyone tried this in a humid climate?

Put diatomaceous earth in a small band around the base of the trunk.

If problem is too much for one band put two. Works for me.

Wrapping a ring of 1" wide masking tape on a smooth area of the trunk with the sticky side facing outward....is sure cheap and easy. The rings can be replaced after they are full of bugs or when the stickiness has diminished.

I am surprised no one has suggested spraying the tree with oil to control the aphids and scale that are creating the "honey dew" which is attracting the ants to the tree. Al