We love Hummingbirds. Hummingbirds love sugar water. Ants love sugar water. We do not love ants. Ants do not love ginger. Therefore, must put ginger between ants and sugar water.
Solution: Take cap from a jug of milk, drill a hole slightly smaller than the size of the wire holding the feeder in center of cap, slide the cap on the wire, fill it with powdered ginger. No more ants! Hummingbirds don't seem to care. Cool.
Update: Ginger works really well with the tiny sugar ants, but the big red ants just arrived, and though they don't like it much, they fight through to the sugar.
I've put a little oil on the wire hook and that has stopped them. For now.
K says the ants are evolving and will soon have feet that can walk through oil. She reads way too much, in a good way.
More updates as warranted.