AMDRO is the best I use to sell it when I worked at Ace hardware customers loved it Conundrum is right the little ants wont touch it because the grains are to big so get two boards and crush some of it up into a powder so the little ones will take it. It works have told many a customer to do this and I have done it myself. Do not Eff with them they could bite or sting you. There is a old trick borax soap with sugar mixed together that I have heard works. But with a colony of that size you need amdro.
Good luck!!