From the volcanic ash that was left from the formations of the Rocky Mountains, this Mason Bee Clay is a great source of clay for the bees because it holds its form after drying. We advise using this clay if you want to help the bees maximize their reproduction capacity by keeping this clay moist and about 20 feet away from the bee house. This will put less stress on the bee because it will not have to fly as far to find the right type of clay, allowing the bee to spend more time in the flowers pollinating.