How can I make an ant moat for my hummingbird feeder?

Drill a hole slightly bigger than the hang wire through an old spray can lid. Slide the lid onto the wire. Seal the gap between the hole and the wire with silicone or hot glue. Pour some water in the cap. Do not use oil, because some small birds drink from ant moats. The best way to use an ant moat is to put the cap on upside down, then coat the inside of the cap with a product called Tanglefoot, which is available at nurseries and maybe Wal-Mart type stores. Something else that's sticky but won't dry out would also work.