It all started with an unexpected observation in 2022. A technician from Cornell University brought a jar filled with bees found in an Ithaca cemetery back to her laboratory. The researchers quickly identified the species: Andrena regularis, a solitary bee that nests in the ground and actively participates in pollination.
Upon studying the site, the scientists discovered a colony of exceptional size. Between 3 and 8 million individuals occupy an area of approximately 6,000 square meters (about 1.5 acres). Such density is equivalent to several hundred hives of honeybees, concentrated in a small space.
Illustration image Unsplash
According to the study published in
Apidologie, this population is among the largest ever documented. The researchers point out that other comparable aggregations likely exist but remain unknown due to a lack of detailed observations.
Unlike social bees, these insects live alone. Each female digs her own burrow, lays her eggs inside, and provisions them with pollen and nectar. The larvae develop entirely underground before emerging the following spring.
A notable characteristic of this species is that it overwinters underground in the adult stage. As soon as spring temperatures rise, the males emerge first, followed by the females a few days later. This staggered emergence promotes reproduction as soon as they appear.
This emergence coincides with the blossoming of apple trees, an iconic crop for the region. Located near orchards, the cemetery thus provides an ideal starting point for pollination. The bees also forage on surrounding wildflowers.
Local conditions partly explain this concentration. The sandy soil facilitates nest digging, the absence of pesticides, and limited disturbances favor their long-term establishment. Cemeteries thus appear as unexpected refuges for biodiversity.
The researchers used emergence traps to estimate the population. These devices capture insects as they emerge from the ground, allowing for the estimation of their density and activity period. They also revealed the presence of parasitic bees, which lay their eggs in the nests of other species.
This discovery also shows the importance of preserving these discrete habitats. A simple alteration of the terrain could wipe out millions of individuals at once.