well that is partially true but boots can be cleaned in an attempt to rid them of any invasive species, very very small organisms such as eggs,larva,pupa etc of bugs get stuck in the felt and are near impossible to clean out. atleast this is what i was told. so yes, even if they ban felt there is still a problem. not everyone cleans their boots and wading gear,and there is always that bug that manages to go unseen and then spread to another waterway. i clean mine everytime i get home, wash the outside of my waders and check my boots and the rest of my gear for anything i don't want hitch hiking to another river