This 300 count case of Phragmites reeds are what is needed for a busy well established Orchard Mason Bee host location. No paper liners are required, but maybe used if they will fit into the slight variation in diameter of the natural reed. They replicate the natural holes Orchard Mason Bees prefer and are considered single use, if they are occupied during the OMB season, as cocoons can not be removed without splitting them apart