Try "bee proof" feeders and/or inserts like those in the affiliate links below. If the bees tongue can reach the syrup they will continue to come until the syrup is gone. You want to create a hummingbird feeder, not a bee feeder. Think how long the tongue of a hummingbird is. Also, please consider the hummingbirds need to migrate, so you might think of the time of year and if it is their natural time to leave. Pulling your feeder may prevent some unnecessary deaths if they get caught in freezing temperatures.
Notice no bees on my feeder! I have over 100 hives in a three mile radius!
Click on these links to purchase Feeder or inserts
The above affiliate links are to products we personally use in our apiary and on the homestead. "We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites."