Here's a real quick Pro Tip:
If you have bees around your hummingbird feeder, or worse bees and flies floating in your nectar there is an easy fix for this. At least with the line of Aspect Hummingbird Feeders.
I like the window feeder pictured below. However as soon as I put it up I found flies floating in the nectar. I know what the issue is... the holes for the Aspect Jewel Box feeder are too big thus flies and bees can get to the nectar. Luckily Aspects created a product to solve this problem.
The product is a set of Nectar Guard Tips. Basically you put these small rubber tips on the inside of your feeder. The underside, beneath the ports, have little pieces of plastic ready to receive the tips. I simply squeezed the tip onto the plastic. Done: No more floating flies!
Enjoy the hummingbirds this year and change your nectar often.