( NATURAL REEDS ) new un- used 5" to 6"reeds.Mason bees prefer these reeds over any other nesting material. These reeds keep parasitic wasps out to prevent losing all your future mason bees to these parasites and naturally breath to help prevent mold problems . These easy to open reeds are the way to succeed in raising mason bees. These are great reeds to use with leaf cutter bees, cornifron mason bees and other small mason bees. We recommend the large nesting reeds for the blue orchard mason bees. New un-used reeds are needed to be used each year.