Look into making up a batch of boric acid bait.
The concentration needs to be around 1% with the rest taken up by sugar
and some form of flavorant. figure 1 oz of boric acid 5 lbs of sugar
and a quart of water, make the sugar syrup and stir the boric acid in
while it's hot and then add a small jar of mint jelly so the ant's can
find it by smell.
I load it into small pieces of bamboo and set em around near the
mounds.
It takes a while before it works but it kills the entire colony.