Just got home from a 4 day business trip. My daughter "picked my figs for me" while I was gone, i.e. she picked the wrong ones off the trees in pots on the porch ;-) 

So I went through the yard picking. Many had soured and were full of ants because of all the rain we've been having. I found a few good ones.

The first ripe one off my unknown I thought was good (looked OK), but when I bit into it, the fig was soured and full of ants. That was nasty! It will take a day or three before I want to eat another fig ;-(

For your single trunk trees couldn't you put tanglefoot around the trunk to stop them from climbing? That is what I do for my stonefruit (too keep ants from farming aphids on them)

I have very tiny ants that are on one of my Italian Honeys they are so small they can fit in the hole on the bottom of the fig I usually blow them off and eat them in some countries ants are a delicacy  :-) 

I don't mind blowing the ants off the fruit, but a mouth-full, along with it being soured - that was nasty!

I guess I'll never see you on an episode of FEAR FACTOR then LOL 

As a missionary and anthropologist I've eaten things that most Americans would kvech at, sheep eyeballs and fermented horse milk when I lived in Central Asia for example. But I don't spend so much time tending my figs in order to eat them soured and full of ants.

Ants will actually consume a whole fig down t the stem in given the opportunity. They don't seem to contribute to souring - that is mostly from fruit flies and beetles.

I leave ant stakes in bowls around my yard.  If it rains I either use a plastic tent over them or an inverted bowl.

I have ants that are about 1/2 long and black. About 10 ants can eat a hole fig in a couple hours. No lie i put seven dust but its raining everyday now and flooding. I live in Louisiana and we are getting lots of H20.

I had ants eat a fig the other day. My figs don't seem to be ripening that fast, and when they do, the birds get to them first. Very frustrating.

Try sprinkling used coffee grounds around the base of the tree. It works pretty well for me.