Yes, cedar does "help" prevent decay and insect attack. But NO it most definitely will not prevent wax moth, shb, or varroa damage. None of these are pests of wood but instead they are pests of what lives within these wooden hives. It's important to note that wax moth and shb are much worse in some climates than others. Leave dark, pollen filled comb unattended in the heat of a Midwestern, southern or western US summer and I guarantee you that you will have wax moth pretty much everywhere regardless of the type of wood and you will find shb in most southeastern coastal climates. MB is quite correct, I am sure I wouldn't have much trouble finding some old cedar boxes rife with wax moth cocooning scars.