Bee guards...Perky Pet has them for their feeders, but if you have a different brand, they might not work. We had wasps that were partial to the feeder earlier this year. At first, the hummers avoided the feeder until the wasp(s) left. Later in the season, the hummers would sit and drink opposite the wasps. Buying a hanging basket with flowers that hummers love helped so they now have a choice and the wasps have gone elsewhere.