These replacement tubes can be inserted into mason bee nests to replace old or tired tubes. Mason bees are excellent pollinators of a wide variety of spring and summer blooming trees, flowers, fruit and herbs. Simply place a mason bee nest in your garden facing due south, in full sun (not dappled shade) and pointing slightly down for drainage, to attract the bees and provide them with a safe nesting habitat. These replacement tubes can be inserted into mason bee nests to replace old or tired tubes.