A morning walk through East Lawn Cemetery in Ithaca, New York uncovered an immense colony of some 5.5 million subterranean bees. The discovery, which a Cornell University research team published in April in the journal Apidologie, documents one of the largest aggregations of these insects ever recorded in the world. The population, belonging to the species Andrena regularis, occupies an area of about 1.25 acres and is crucial for pollination of the region’s orchards, demonstrating that historic cemeteries can prove unsuspected refuges for urban biodiversity.

The Genesis of the Discovery

It all began in the spring of 2022, when Rachel Fordyce, then a laboratory technician in Cornell University’s entomology department, noticed an anomalous presence of insects during her usual walk to work. After collecting some specimens, she showed them to Bryan Danforth, an entomologist at the same university. Analysis revealed that they were Andrena regularis, commonly called the mining or miner bee. Unlike honey bees, this wild species has a solitary lifestyle and nests by digging tunnels in the ground. Historical records indicate that the insect has been present in the cemetery, established in 1878, since at least the early 1900s.

The Census

To calculate the size of the colony, scientists placed 10 traps placed in the cemetery between late March and mid-May 2023. These small net curtains cover less than one square meter of soil and channel insects coming out of the ground to a glass container. In total, more than 3,000 insects belonging to 16 different species were sampled, including bees, beetles, and flies, with an overwhelming prevalence of Andrena regularis. Extrapolating from the average density found in the traps, the researchers estimated a total population of between 3 and 8 million, with an average value of 5.5 million—the equivalent of more than 200 domestic bee hives.

The research yielded previously unpublished data on the biology of this little-studied insect. The traps revealed that males emerge from the ground a few days earlier than females during the first warm days of April, a strategy that maximizes mating opportunities. Subsequently, females dig nests and lay eggs in cells filled with pollen and nectar. The species has the distinction of wintering at the adult stage underground, which allows it to become active very early in the spring, in perfect synchrony with the flowering of apple trees in the nearby Cornell University orchards. Monitoring also revealed the presence of complex ecological dynamics, such as parasitism by bees of the Nomada imbricata species, which lay their eggs in the nests of the host species at the expense of the original larvae.

A Heritage to Conserve

The discovery highlights the need to protect the nesting sites of wild bees, 75 percent of which are solitary species living underground. Places such as old city cemeteries offer ideal conditions: sandy soils that are easy to dig, no pesticides, and an environment that is not subject to the profound alterations typical of intensive agriculture or housing development. To prevent populations of this magnitude from being accidentally destroyed by concrete pours or road work, the study’s authors have launched a global citizen science initiative. The project invites citizens to report the presence of underground bee aggregations in order to survey and protect these vital pollinators before habitat fragmentation jeopardizes their survival.

This story originally appeared on WIRED Italia and has been translated from Italian.