Urban beekeeping: for 3Bee it's not just placing hives, it's an on-site project

In recent years, beehives have moved onto the rooftops of offices, hotels, and facilities. Urban beekeeping brings people closer to bees, but on its own it does not increase biodiversity: the honey bee is a farmed animal and in the city it seeks the same flowers as wild bees. In Paris, a study published in PLOS ONE measured that where there are more colonies within a 500-meter and one-kilometer radius, wild pollinators visit flowers less, with the strongest effect on large solitary bees, beetles, and bumblebees. In 14 Swiss cities, beehives doubled between 2012 and 2018, from 3,139 to 6,370, and the available flowers are no longer enough to sustain them (npj Urban Sustainability). One more beehive without more flowers takes space away from nature instead of giving it: we also talked about it in Bees in the city, let's be clear.

When we say bees, we think of a single species, but almost 2,000 (Apoidea) live in Europe and most are solitary bees: they don't make honey, don't live in colonies, and rarely sting. Each female digs her nest in the ground or builds it in hollow stems, wood, and cracks in walls, and many visit few plants. They are the first to disappear when flowers and places to nest are lacking. That's why in a 3Bee project the beehive is not the starting point: we start from pollinator refuges, such as the Polly House wooden houses with reeds of different diameters for mason bees and other solitary bees, alongside butterfly and ladybug houses and patches of bare ground for those that nest in the soil. Beehives come later, in the number the land can support.

The heart of the project is the biodiversity oasis: an area of your premises, whether a garden, a flowerbed or a roof, transformed into a habitat with native nectar-rich plants that bloom in different seasons, less mowing, and shelters. There are also beehives, but only if the numbers allow it. With XNatura® we calculate by satellite the nectar potential of the site and surrounding area, that is, how many kilos of nectar the plants present produce each year, and the abundance of pollinators that habitat can host, combining flowers and nesting sites with the InVEST model. We reserve at most 10% of the available nectar for honeybees, and from that we derive the number of hives, which can also be zero. Then Spectrum verifies in the field that wild pollinators remain abundant.

The model also works in the heart of the city. On the roof of the Prometeon SuperLab in the Bicocca district of Milan, 4,200 m² of industrial roof have become a refuge for pollinators: 16 Polly Houses for solitary bees, 7 butterfly houses, 7 for ladybugs, and native nectar-bearing plants. In the first year, the Polly Houses hosted approximately 6,800 solitary bees (estimate), and the roof became a stopover and foraging point in the neighborhood's ecological network. A 3Bee on-site project is built like this: site analysis, oasis and shelters, hives in the number calculated based on data, sensors, and a platform with data to share with colleagues, clients, and sustainability reports. If you want to turn your site into an oasis, tell us about the project.