She collected some in a jar and brought them to her supervisor, Bryan Danforth, professor of entomology in Cornell's College of Agriculture and Life Sciences.

"These are all over the cemetery," she told him.

The insects were identified as Andrena regularis, commonly called the "regular mining bee," a solitary wild bee species that nests underground and helps pollinate crops and wild plants.

That simple observation led to an extraordinary discovery. Researchers found that the cemetery contains one of the largest and oldest known aggregations of ground nesting bees ever documented. Scientists estimate the site is home to roughly 5.5 million individual bees concentrated within a 1.5 acre area. According to the researchers, that is comparable to more than 200 honeybee hives and exceeds Manhattan's human population by more than threefold.

"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 '24, lead author of the study published April 13 in the journal Apidologie.

Hoge conducted the work as an undergraduate researcher in Danforth's lab.

Why the Cemetery Became a Bee Haven

The study explored the biology of these poorly understood wild bees while also highlighting their importance as pollinators for valuable agricultural crops such as apples, one of New York's signature commodities.

"The research elevates the value of solitary ground-nesting bees and shows just how abundant these bees are, how important they are as crop pollinators, and that we need to be aware of these nest sites and preserve them," Danforth said.

Historical records showed that A. regularis has been present at East Lawn Cemetery since at least the early 1900s. The cemetery itself dates back to 1878.

Scientists say the discovery strengthens the idea that cemeteries can act as important refuges for biodiversity. Older cemeteries, especially in cities, are already known to shelter uncommon plants, insects, birds, and mammals.

Keven Morse, superintendent of East Lawn Cemetery, said he has seen deer, geese, hawks, foxes, coyotes, and countless bees during his family's 46 years helping manage the nonprofit cemetery.

"And of course, bees, which he said have never stung him."

"I just felt bad having to mow in certain areas," Morse said. "There's probably three or four sections where they really migrate heavy, there's a lot of them."

Researchers explained that cemeteries provide especially good habitat because the land is peaceful, rarely disturbed, and largely free of pesticides.

Most Bees Actually Nest Underground

Although honeybees receive most public attention, about 75% of bee species are solitary ground nesters like A. regularis.

"It's the most common lifestyle for bees," Danforth said.

When Hoge began researching the species, he found surprisingly little scientific information available. One of the most detailed references dated back to 1978, giving the team an opportunity to better document the bee's biology.

Female A. regularis create underground nests and place eggs in chambers filled with pollen and nectar. The larvae develop beneath the surface before emerging as adults.

"This species overwinters as adults, which is relatively rare, and that's part of the reason why they come up out of the ground so early in the spring, timed to the apple bloom," Hoge explained.

The bees also visit fruit trees and wildflowers that bloom early in the season. In New York, they typically emerge in April when daytime temperatures begin regularly reaching around 70 degrees.

Cornell Orchards, located about one third of a mile from the cemetery, may help support the massive bee population by providing abundant spring flowers. Danforth also noted that the bees prefer sandy soil, which the cemetery contains in large amounts.

How Scientists Counted Millions of Bees

To estimate the bee population and study emergence patterns, researchers used a new monitoring method involving emergence traps. These small mesh tents cover less than a square meter of ground and funnel emerging insects into glass jars.

"You capture a whole community of animals coming out of the ground with this approach," Danforth said.

Between March 30 and May 16, 2023, the research team placed 10 traps throughout the cemetery. They collected 3,251 insects representing 16 species of bees, beetles, and flies. A. regularis overwhelmingly dominated the samples.

Researchers used the number of bees captured in each trap to calculate average bee density across the cemetery's approximately 6,000 square meters. Based on those calculations, the estimated total population ranged from about 3 million to 8 million bees, with an average estimate of 5.5 million.

The traps also revealed differences in emergence timing between males and females. Male bees appeared first during warm periods in April, while females emerged several days later.

"The males come out first and wait for the females, so that they have the best opportunities to mate and pass on their genes," Hoge said.

Bee Parasites and Conservation Concerns

The study also documented brood parasitism by nomad (or "cuckoo") bees (Nomada imbricata). These bees wait until A. regularis females have prepared brood cells underground before laying their own eggs inside them.

Once the nomad larvae hatch, they kill the host bee larvae and consume the stored pollen and nectar intended for the mining bees.

To help locate and protect similar nesting sites, Danforth and his colleagues have launched a global citizen science initiative encouraging people to report ground nesting bee aggregations they encounter.

"These populations are huge, and they need protection," Danforth said. "If we don't preserve nest sites, and someone paves over them, we could lose in an instant 5.5 million bees that are important pollinators."

The study's co-authors included postdoctoral researchers Jordan Kueneman and Katherine Odanaka, undergraduate students Steve Hoge '24 and Cassidy Dobler '26, and lab technician Rachel Fordyce.

Funding for the research came from the Cornell Atkinson Center for Sustainability, the National Science Foundation, and the Federal Capacity Funds program.