Ants do not necessarily get repelled by Vaseline. But it does create a slippery surface that’s tough for ants to move across. One solution is to apply a line of petroleum jelly like Vaseline around the feeder's base. Ants can't cross over the jelly. Their inability to cross will create a barrier between them and the nectar. You can also add some Vaseline to the feeder's pole. We bet that slows ants down. Big time!  (More on protecting your hummingbird feeder's pole in a moment.)