There are a couple of things you can try to reduce the bee problem at your hummingbird feeder. Try spraying or dabbing vegetable oil on and around the ports where the bees are feeding. This will not bother the hummingbirds, but should deter the bees. Another possibility is to install "bee guards," on the ports. They are little round cages that allow the hummingbirds to feed with their long bills, but keep the bees from reaching the sweet fluid. Bee guards are available at most bird supply stores.