If you don't stay on top of cleaning these, say you let it go a year without cleaning, they get so bad that nothing will remove the grime and mold. Buying this set of replacements is an inexpensive way to bring your feeder back to like new, and no doubt better for the birds. I honestly don't think a bee guard is even really a necessity in our area, but the feeder looks better with them in place. :) I only wish I could buy them in a slightly larger pack at a reduced price, since we have three of these feeders!