Sugar water in a hummingbird feeder should be replaced every 3-5 days. Use simple table sugar in your feeder and not honey. If honey goes bad outside, it can form a fungus that attacks the hummingbirds beak and tongue and is fatal. And to be completely safe, don’t use red-dyed hummingbird nectar. They can’t digest the dyes and it isn’t necessary to attract the hummingbirds. Finally, don’t put too much sugar in the solution. More is NOT better. Use one part sugar to 4 parts water.