The majority of wild bee species are solitary, which means they don’t live in colonies like honey bees or bumblebees, but alone. Although most solitary bees nest in soil, some species nest in cavities in trees, stems, and twigs. These cavity-nesting bee species will consider renting a room in a so-called bee hotel.
Bee hotels are not new. We have been using them in agriculture since the middle of the last century, to improve pollination in orchards and other crop systems. Recently, bee hotels have become more broadly popular, mostly due to media attention given to the worrisome decline of wild pollinators across Europe and North America.
Whether bee hotels can help declining pollinators will depend somewhat on the context. In complex, natural habitats wild pollinators do not lack nesting resources. Setting up a bee hotel in such places will not do any harm, but it probably won’t have much of a positive effect either. In natural habitats, bee hotels can have an educational or research role. But in anthropogenic habitats that lack complexity, such as urban or agricultural areas, nesting resources are limited, so setting up a bee hotel can have a positive impact.
If you are planning to build a hotel, you should keep in mind the other important factor for bees: the availability of food. Most small solitary bees do not forage far from the nest, up to several hundred meters. If you are setting up a bee hotel in your garden, you can improve the floral resources very easily. Dandelions, daisies, and clover are great sources of nectar and pollen, so mowing less frequently is often the best thing you can do to help the pollinators.
Bee hotels can vary in design, but most are built from narrow horizontal tunnels or tubes, closed at one end. Each of these tunnels will serve as a nest for one female solitary bee, which will build individual rooms, one after the other, along the tunnel. In each room, the bee will lay a single egg that will develop into a larva, and supply it with food – a ball of nectar and pollen. Walls between rooms are built from mud, resin, small pieces of leaves and petals, or pebbles, the building material depending on the bee species.
Making a bee hotel is simple, but you need to keep in mind a few rules. We explain these in a short leaflet, which you can find at the end of this post. We created the leaflet together with students from Section for Hymenoptera of “Biology Students Association – BIUS“. Their section studies all Hymenoptera (including bees, ants, and wasps), but their main focus are wild bees, and they have practical experience in building bee hotels. If you are a biology student interested in wild bees (or ants or wasps), get in touch with them – they plan exciting activities for when it warms up.
To keep in mind:
- If you are ambitious, it is better to build several small hotels than one large. Big hotels attract more predators and parasites.
- Maintenance matters. Remove the used tubes and replace them with new ones each year. Replace drilled wooden blocks every two years.
- Meadow flowers are not the only food source for bees – many trees and shrubs are rich in pollen or nectar.
Download the Bee Hotel leaflet (in Croatian)