Creating a Hotel for Native Bees

I enjoy gifts that lead to interesting projects.

For a gardener, there are many possibilities for such gifts, definitely including plants that would complement the landscape, or add something that is both compatible and unusual.

This year, my most intriguing gift is a “hotel” for native bees. It qualifies as a hotel by including nesting facilities for multiple occupants.

This gift leads to an interesting study of the bees themselves, and of ways to entice them into using the hotel.

Some 4,000 species of bees are native to North America. This column is not suitable for an overview of native bees, but it is worth noting at the outset that the familiar honeybee (Apis mellifera) is not native to this part of the world, but emigrated from Europe to the United States.

Native bees are excellent pollinators, more efficient than honeybees in that work. An important difference between these groups: most native bees are solitary, nesting in cavities or the ground, while honeybees are social, nesting in hives.

According to the Xerces Society (which seeks to conserve bees and other invertebrates) about thirty percent of our 4,000 species of native bees nests in cavities that they find or create in nature. The other seventy percent nest in the ground. There are also few other native species, like the Western Bumblebee (Bombus occidentalis) that are social creatures that nest in larger cavities. 

My native bee hotel would be of interest, hopefully, to cavity-nesting species that live in central California. My initial expectation was that this nest would attract mason bees, but the Xerces Society lists only a few species that are found primarily in Washington and Oregon. There are many other species, however, including the Blue Orchard Mason Bee (Osmia lignaria),that might live in California.

Another cavity-nesting native bee species that could appear in my garden is the carpenter bee (Xylocopa californica), which, according to Las Pilitas Nursery, will spend weeks digging a 1/2 by 4–to–6-inch hole into a tree for their nest site. We might expect that carpenter bees would be attracted to a nest that is already for occupancy.

In addition, many other species of native bees might welcome this native bee hotel.

While there will be variations in nesting by different native bee species, the common model has the newly hatched female bee emerging from its nesting place in the early spring, and busily mating and seeking a cavity for its eggs. The bee gathers pollen to stock the nest, then deposits an egg, and seals the nest with a wall of mud. The bee repeats this process so that a single cavity could include five–to–eight chambers, each with its own egg and pollen stash.

During the summer, the eggs develop into larvae, then into pupae, and finally into adults, which remain in the nest until the following spring.

To support this process, the hotel manager, i.e., the garden host, should install the nest complex in a east- or southeast-facing location, where it will enjoy morning sunlight. It could be three–to–six feet above ground for convenient observation, and near a good supply of flowering plants (preferably California natives) and mud for construction of nest chambers.

I will plant a selection of California native annuals near this nesting unit, for the bees’ easy access to pollen. I will also provide a supply of muddy clay soil, for the bees’ use. My garden’s clay occurs in a rather deep layer, so I will need to import some clay soil, and keep it moist in a container, such as a large saucer for a plant container.

A good source of seeds for pollinator flowers is the Early Blooming Beekeeper’s Mix, offered by Renee’s Gardens. This mix includes twenty-two varieties, many of which are California native plants.

Bee experts recommend moving the nesting unit into a dark, unheated garage or shed during the winter months to protect the bees from predators. The gardener should then return the unit to the garden in the early spring, well before flowers bloom. As the days warm, the gardener can watch for the new generation of bees as they emerge from the nests.

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