About the only effective method I've ever found is to drop a large handful of sugar on the ant hill and water in thoroughly. It encourages bacterial and fungal growth, which the ants hate.

However, it doesn't kill them, they just move somewhere else. Usually that's good enough for me, and I end up with ants in a location I don't care about.

On the up side, ants are generally harmless and not terribly annoying (if not in the house, of course), and perform a very positive function by deeply aerating soils. My response to them is to ignore whenever possible as they don't damage the lawn or gardens in the slightest.

Morph's approach will work perfectly for fire ants and other protein loving ants. For sugar ants, not so much. But if you added a teaspoon of bread yeast to the sugar, that should do it.