Promoting pollination with bee houses and how to build one.
There are several types of nest for sale, some of them quite expensive. However, many are inadequate and will not be occupied. Even worse, they may be harmful to bees. Marc Carlton, who runs the Pollinator Garden website, and Xerxes Society (an American organisation dedicate to the conservation of invertebrates) have provided detailed information of how to choose or build bee houses, and how to maintain them.