There are approximately 5,000 native bees in North America, 70% lead a solitary life this means they do not build colonies like bumble bees, honey bees, or meliponinos (Central and South America, Africa and Australia native species). Solitary female bees make and provide food for their brood individually in their nest, some species form aggregations living close to members of the same species. 30% are cavity nesters, building their nest in small tunnels like hollow dead plant stems, abandoned borer-beetle holes snags etcetera. If they lack this type of structures, it limits their nesting opportunities, and bee decline has been attributed in part to habitat destruction.
Before we talk about how to build a bee box, it is important to know how a female bee would arrange the housing opportunity you will provide!
First, the female bee will carefully select the area where she would be placing her babies (brood); usually, they do not like rough interiors, once selected she will build tiny barriers to divide the tunnel into a linear row of brood cells. Walls can be constructed of mud, plant resins, leaf pieces, flower petals and glandular secretions. Second, she will provision each brood cell with a mixture of pollen and nectar, or like some people like call it bee-bread, but consistency differs from bees species to bee species. Then, she places a single egg into the cell, where food will be ready for the developing larvae, she closes the cell and continues into the next one. This offspring will go through the egg, larval and pupal stages in the cell, and come out as an adult the next year to continue the cycle.
From an outside observation, it’s difficult to see if the female bee filled along the tunnel completely, if a female bee is able to complete the tunnel before dying she would block the entrance with mud, leaf pieces, and other nesting materials to keep her brood safe from predators.
A vital detail about cavity nester bees, a female bee has the ability to know the sex of the egg she lays in the tunnel, male eggs will be closer to the entrance and female eggs will be safe in the deep of the tunnel. This way males will get out first waiting for the female to emerge several days later to mate.
There are many things we as conservationists can do to help stop bee decline, one is to provide food via pollen and nectar, and the other is to build alternative habitats in the form of nesting boxes, or nesting landscapes.
If you decided to build a bee box you must know this requires serious maintenance! like any other house, bees need to be safe and healthy in their own homes. Diseases and parasites or other insects can interfere with our bee box if we do not maintain it properly.