The silence and tombstones of cemeteries hide more than it seems. In the East Lawn Cemetery of Ithaca, New York, a group of researchers from Cornell University has discovered something extraordinary beneath the ground: a colossal underground colony of bees.
In early 2023, they estimated that more than 5.56 million specimens of the species Andrena regularis emerged from an area of just 6,523 square meters.
This finding is astonishing not only because of the number of bees but also because of the unusual environment. Surprisingly, a species that does not build hives is concentrated in such a small area. The density of this aggregation is comparable to gathering between 140 and 270 hives of honeybees in the same space.
Contrary to what we imagine when thinking of bees, Andrena regularis does not live in hives. Each female digs her own nest in the ground, where she deposits pollen and nectar for her offspring. Approximately 75% of bee species follow this solitary and underground pattern.
Millions of bees beneath a cemetery
The life cycle of Andrena regularis is synchronized with the arrival of spring. These bees spend the winter underground and emerge when the first apple and other fruit tree blossoms begin to appear, taking advantage of the scarcity of competitors.
The discovery began unexpectedly in 2022 when Rachel Fordyce, a Cornell technician, detected the massive presence of bees on her way to work. This led the team to set up traps to capture and study the bees emerging from the ground between March 30 and May 16, 2023.
These traps, covering areas of 0.36 square meters each, allowed the researchers to collect 3,251 insects from 16 different species, with Andrena regularis being the most prevalent. The calculated density was 852.78 bees per square meter, extrapolating to a population of 5.56 million.
In addition to the bees, the study documented the presence of parasites such as Nomada imbricata, a cuckoo bee that lays eggs in other nests. An estimated 77,914 of these parasitic bees emerged, with a parasitism rate of 1.4%, lower than in similar studies.
The key to the success of this colony lies in the characteristics of the soil and the absence of disturbances such as pesticides. The sandy soil favors excavation and the proximity of Cornell Orchards provides a nearby flowering environment.
This phenomenon highlights the importance of conserving underground spaces for pollinators, often overlooked in favor of aesthetically pleasing but less functional gardens. Preserving these habitats can be crucial for maintaining populations of bees that are vital for the pollination of crops and wild plants.
The results of this research have been published in Apidologie, revealing a hidden world beneath our feet that demands our attention and care.
