1 cup. Provide quality, natural nesting material for Mason Bees. This clay-rich mud substrate is what female bees will use to create their nests inside your provided home, filling the end caps of tubes, or reeds with a clean protective barrier for baby bees. Mud is vital for mason bee reproduction—females won't nest without a nearby, reliable source. Simply mix this clay mud and place nearby for her to use! Packaged in a 100% recycled paper bag. Full instructions are included with purchase, or you can find them below.