Groundnesting Bees

Sacred Bee Space

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By: Ross Conrad

Today’s beekeepers are very familiar with bee space. It lies at the heart of the removable frame hive design, and led to the development of an entire industry built around the European honey bee. It turns out that our native solitary bees are managing to find their own bee space in an increasingly hostile world.

Bees are under assault from a variety of stressors. Despite this, our European honey bee is holding its own since they have an army of beekeepers out there caring for them and looking out for their welfare. Native solitary bees unfortunately, do not have such assistance and all indications are that they are experiencing dramatic decline. This decline threatens to severely disrupt the foundational ecosystem service of pollination across both cultivated and wild plant communities. (Dar et al., 2025).

Estimates are that there are approximately 20,000 species of bees on our planet. Approximately 75% of them are solitary. This means that unlike in a honey bee hive with its division of labor and cooperative brood care, each solitary female bee constructs her own nest, provisions her own brood cells, and lays her own eggs.

Even though honey bees are the work horses of agricultural pollination, native solitary bees play an important role in plant propagation. Not only are they great pollinators in their own right, but they also increase honey bee pollination effectiveness through synergies with Apis mellifera. Honey bees alter their foraging behavior when solitary bees are present. This results in a higher proportion of fruit set in orchards. (Brittain et al., 2013).

Cemeteries Come Alive
A recent paper published by researchers working at the Danforth Lab of Entomology at Cornell University in Ithica, N.Y. documents one of the largest populations of ground-nesting bees in the literature (Hodge et al., 2026). It turns out the bees were living right next door.

Danforth Lab technician, Rachael Fordyce was cutting through the East Lawn Cemetery after leaving work one day, when she noticed an impressive amount of bee activity. She was already kind of clued in since she and her colleagues were studying the brood cell microbiomes of solitary ground-nesting bees in order to illuminate what happens when a pollen packet is buried underground with an egg to help the bee that will hatch, to survive until the following Spring. She alerted the lab to her discovery and much to their surprise they found what appeared to be a staggering number of ground-nesting bees living on the cemetery grounds.

To confirm their discovery the researchers used emergence traps: small mesh tents that cover less than a square meter of ground and direct emerging insects into a glass jar. In the Spring of 2023, the team deployed ten traps in the cemetery to document the size of the bee aggregation. Sixteen different species of bees, flies, and beetles were among the 3,251 insects they collected. Andrena regularis Malloch (the regular mining bee) was by far the most commonly trapped species. The team estimates that the number of miner bees living at the cemetery during the year of their study to be somewhere between 3.1 and 8 million bees (an average of 5.5 million).

Islands of Hope
According to the Senior Research Associate in the Danforth Lab, Jordan Kueneman, “It’s not all that common to find a site of this magnitude and density, but there are others. We’re studying one that’s somewhat equivalent in North Carolina, also at a cemetery. We know of other sites in hay fields, or fallow fields, places where development isn’t happening for whatever reason. It’s sort of like a needle in the landscape haystack where these things occur.”

While most of the media attention around this recent discovery has been focused on the dominant species, A. regularis, there are a lot of other species also nesting at the East Lawn Cemetery. This included 5 other species of bees, as well as bee parasites such as the cuckoo bee, which like the cuckoo bird, will lay its eggs in a solitary bees nest and leave it to the unsuspecting bee to provide for the cuckoo bee’s offspring.

As Kueneman explains, “So even among these dominant bee species, there are less abundant bee species that are using the same resources and they partition themselves in time. Our study went through the Spring, but if we kept it going through the end of Summer, there are other species that would have come out…There is a hypothesis, the selfish herd hypothesis, that predicts that nesting as a group may reduce the risk of predation or parasitism. So, there are evolutionary reasons why this may occur. I find it fascinating that other species of bees would feel comfortable intermixing and being one among many others, but it seems to happen that way.”

Apparently, cemeteries can act as a kind of oasis for solitary bees. The habitat in cemeteries is exceptionally good since the grounds are peaceful, rarely disturbed, is considered sacred and therefore normally preserved, and are mostly free of pesticides. Old cemeteries in particular (> 100 years old) are typically located in areas with sandy soil, since it was easier to dig by hand; the same soil type that ground-nesting bees prefer. Cemeteries also have an edge when it comes to documenting the age of the grounds, since cemeteries are some of the best places to find old, and accurate records. As one research paper put it, “cultural traditions against disturbance of burial places have ensured, in some cases, that cemeteries contain a portion of the landscape that has undergone little disturbance over a long period of anthropogenic landscape transformation.” (Barrett and Barrett, 2002).

The Rising Seas of Climate Disruption
Even though cemeteries are often biodiversity hotspots, serving as a refuge for animals and plants in places surrounded by human activity, they are also vulnerable to threats like invasive species and the way our destabilized climate is magnifying weather related disasters. Authors of the U.S. Federal Emergency Management Agency (FEMA) report titled, Guide to Expanding Mitigation: Making the Connection to Cemeteries, noted that melting permafrost is creating swamps in Alaska where cemeteries are located, and California gravestones are disintegrating due to wildfires. Coastal cemeteries are also at risk. Hurricane Sandy in 2012 unearthed burial sites on Boston Harbor’s Gallops Island. In 2016 a great flood in Louisiana damaged 35 different graveyards and caused caskets to become dislodged from flooded vaults. Meanwhile, the Anchor of Hope Cemetery, in Hoopersville, Maryland is falling into the Chesapeake Bay. As the FEMA report notes, the long-term viability of cemeteries is threatened if mitigating efforts to counter climate impacts are not taken. They could have added that the unique biological diversity and abundance found in many of these sacred sites is threatened as well.

According to Kueneman, “These nesting sites occur sporadically across the landscape. They are very valuable to the well-being of the species regionally, since they are likely source populations for a lot of upstart populations that develop over the years. It is very important that we figure out where they are, what kind of management structure they are exposed to, and if there’s any way that we can assure, or continue whatever we’ve done in the past that has allowed them to reach these unique numbers…these are important locations that have real value biologically, but also contain societal value as they allow us to learn what are great conditions for these species of bees, if they can be replicated in other areas and whether we can make sure that we understand what’s there before it’s potentially lost. We want to make sure that we have good nesting habitat across the landscape to promote a diversity of bee species that are native to our regions. In order for us to do that, we first have to know where they are, why they’re there, and if it is a good spot for them.”

As Kueneman describes it, just as a honey bee swarm can be miraculous, mesmerizing and spell binding, so too is the sight of thousands of solitary bees all emerging from the ground around the same time after having formed one of these massive aggregations. “I hope everybody gets a chance to go and spend time near an aggregation and just watch it, because it changes your perception of what a bee is very quickly. And there is no worry about them. You can get up really close and they don’t mind you at all. They are doing fascinating work all the time and it’s a cool thing to observe. They are also consistent year after year, so if you know where they are, you know when they’ll be active within a week or so, and they’re there for about six weeks.

“Beekeeping is one of the best introductions for not only bees, but also insect biology and the complexity of the structures of life. Some of these native ground-nesting bees, although solitary, do form these large communities. It’s just a whole different framework of how life exists. I think that anyone interested in insects in any way, and even if they weren’t before, if they see one of these spots, they likely would become interested because it’s unlike anything most people have seen. It’s worthwhile making the effort to go to one if it’s in your area, and it’s worthwhile to report it so that everybody can share in that knowledge and biology.”

As a result of learning about the role some cemeteries play as last major hold outs of so many of our native bees, this beekeeper intends to try to find a little time between unpacking, reversing and cleaning out dead hives next Spring, to visit some local cemeteries on a warm sunny day in spring. With any luck maybe I will catch a glimpse of the short and intense, six-week annual above ground activity of our native solitary bees. To learn more, visit Project GNBee (GNbee.org), a community-science project dedicated to discovering, studying, and protecting our ground-nesting bees.

Ross Conrad is a beekeeper and author and lives in Middlebury, Vermont.

References:
Barrett, G.W. and Barrett, T.L. (2002), Cemeteries as Repositories of Natural and Cultural Diversity. Conservation Biology, 15: 1820-1824. doi.org/10.1046/j.1523-1739.2001.00410.x

Brittain C, Williams N, Kremen C, Klein AM. (2013) Synergistic effects of non-Apis bees and honey bees for pollination services. Procedings in Biological Science (Proceedings B). 280(1754):20122767. doi: 10.1098/rspb.2012.2767

Dar, S., Saad, M., Hasan, W., Devi, Y., Ridouane, F., Alyammahi, K., Masry, S., Bumpy, K., Javeed, K., Hussein, H. and El-Samad, L. (2025), Solitary Bees as Vital Bioindicators: A Comprehensive Review of the Diversity, Decline, and Conservation Imperatives of the Halictidae Family. Entomological Research, 55: e70047. doi.org/10.1111/1748-5967.70047

Hoge, S.T., Kueneman, J.G., Fordyce, R., Dobler, C., Odanaka, K., Danforth, B.N. (2026) Emergence dynamics and host-parasite associations in a large aggregation of Andrena regularis (Hymenoptera: Apoidea: Andrenidae). Apidologie 57, 29. doi.org/10.1007/s13592-026-01256-6