A colony of ground-nesting bees estimated at roughly 5.5 million individuals has been discovered under a cemetery in New York, making it one of the largest bee aggregations scientists have ever documented. The bees were identified as Andrena regularis, commonly known as the regular mining bee, a solitary wild bee species that nests underground and plays an important role in pollinating crops and wild plants.

Researchers say the colony, located across 1.5 acres of East Lawn Cemetery in Ithaca, has likely persisted for more than a century, Good News Network reported.

The reports added that the discovery began with a chance observation in the spring of 2022 by Rachel Fordyce, who worked in a Cornell University entomology laboratory at the time. While walking through the cemetery on her way to work, she noticed an unusually large number of bees.

Fordyce collected several specimens and brought them to her supervisor, Bryan Danforth, a professor of entomology at Cornell University’s College of Agriculture and Life Sciences. “These are all over the cemetery,” Good News Network quoted Danforth as saying.

According to researchers, the colony’s estimated population is equivalent to more than 200 honeybee hives and exceeds Manhattan’s human population by more than three times.

“I’m sure there are other large bee aggregations that exist around the world that we just haven’t identified, but in terms of what is in the literature, this is one of the largest,” said Steve Hoge, lead author of the study documenting the colony. The research was published on April 13 in the journal Apidologie.

To estimate the population size and better understand the bees’ emergence patterns, researchers developed a monitoring approach using emergence traps. The small mesh tents cover less than one square meter of ground and channel emerging insects into collection jars.

“You capture a whole community of animals coming out of the ground with this approach,” Danforth said, the publication reported.

Between March 30 and May 16, 2023, the research team deployed 10 emergence traps throughout the cemetery. During the sampling period, they collected 3,251 insects representing 16 species of bees, beetles, and flies. Andrena regularis accounted for the vast majority of specimens.

Using the number of bees collected in each trap, researchers calculated the average bee density across the cemetery and extrapolated the findings to the site’s total area. Their estimates placed the colony’s population between approximately 3 million and 8 million bees, with 5.5 million representing the midpoint estimate, the report added.