I made ant moats out of spray paint lids and coat hangers. They are also available for a few bucks at lowes and the like.
One of the best ways to keep ants out of hummingbird feeders is to use an ant moat, guard or trap. You can either get a hummingbird feeder with a built-in ant moat, attach a guard or moat to your existing feeder or make your own.
You can get rid of the fire ants by sprinkling Jiffy Corn Muffin mix around the area. The ants eat and carry back the morsels to the queen.....soon your fire ant problem is gone.