Bold claim first: ancient bees nested not in trees or hollow logs, but inside a limestone cave, using bone cavities as brood chambers. This startling find expands what we thought bees could do and where they could do it. And this is the part most people miss: the behavior appears to be a deliberate, communal nesting strategy that spans generations, not a one-off oddity.
A large majority of bee species are actually solitary, not social, and most build nests underground, in decaying logs, or within plant stems. Yet a recent study uncovers something truly unusual: in a cave on Hispaniola, researchers found a cache of fossilized bones that housed tiny bee nests. The nests were formed inside the empty sockets of teeth, marking the first documented case of bees nesting in bones. The researchers, led by Lázaro Viñola-López of the Field Museum of Natural History, analyzed the find and published their results in Royal Society Open Science.
This discovery fills a notable gap in the fossil record. Previously, Caribbean bee fossils were mostly found in amber and were far older—around 20 million years old. The new nests, estimated to be about 20,000 years old, offer a snapshot of bee adaptation in a cave environment and hint at a surprisingly diverse nesting repertoire that isn’t widely recognized today. Viñola-López notes that many Caribbean bees’ ecological habits are still poorly understood, and this finding demonstrates that nesting strategies can be far more varied than commonly assumed. It also underscores the importance of scrutinizing fossils for fade-to-black details that can reveal unusual behaviors in species we think we know well.
The fieldwork took place in the summer of 2022, when Viñola-López and colleagues were gathering specimens for his graduate research at the University of Florida and the Florida Museum of Natural History. The cave itself preserves a layered history, containing fossils from more than 50 species, including rodents, birds, and reptiles. The research team surmises that a family of barn owls inhabited the cave, occasionally regurgitating prey remains that fossilized over time. Other animals—tortoises and crocodiles among them—may have fallen into the cave, contributing to the fossil bed. The cave’s stable, shaded conditions likely aided preservation.
What stood out to Viñola-López was the dirt lining inside the tooth sockets of the bone fossils, which resembled the way some wasps cocoon. Using CT scans, the team confirmed the nests were made of mud and assessed as bee nests rather than wasp nests. Bee nests typically feature a smooth interior crafted from compacted dirt and a waxy lining, whereas wasp nests incorporate saliva and chewed plant fibers. This combination suggests a bee-building mechanism rather than a wasp one.
Nest placement in a cave is unusual enough to surprise experts. “Nest in a cave is a very strange behavior for bees,” Viñola-López remarks. The team also found evidence of multiple generations returning to the same nesting site within a single mandible hole, indicating a likely communal nesting habit rather than a solitary one. While the fossil preservation could not reveal the exact species, the site has been named Osnidum almontei in honor of Juan Almonte Milan, who first discovered the cave.
Experts not involved in the study described the find as a valuable contribution to our understanding of hidden biodiversity. They point out that what we learn from ichnofossils—trace fossils like nests—can illuminate the ecosystems these bees inhabited, even when body fossils are absent. The cave’s humidity and stable soils would have provided a protected, relatively predator-free environment, conducive to nesting.
Viñola-López hopes to conduct further surveys to determine whether this nesting behavior occurs elsewhere, such as in other caves or on other islands, and to identify which bee species were responsible. The broader takeaway is striking: bees have demonstrated an extraordinary range of nesting strategies across deep time, including bone cavities and subterranean caves. This challenges the assumption that modern bees are the pinnacle of bee nesting behavior and reminds us that evolution often hides surprising strategies in plain sight.
Further commentary from experts in paleontology and ecology emphasizes that bee evolution has been shaped by long-standing soil-bee relationships and environmental pressures. Insects have adapted to changing habitats for hundreds of millions of years, and ground-nesting bees have been around for a substantial portion of that history. The cave-find underscores that bees can surprise us by revisiting ancient practices and adapting to niches we might never have anticipated.
If you’re curious about what this means for our understanding of bees today, imagine a world where bee nests could be hidden not only in trees or underground, but inside bones and caves—an ancient example of ecological ingenuity that still resonates with ongoing questions about biodiversity and adaptation.
Would you like to see additional comparisons to other unusual bee nesting sites, or a brief explainer of how CT scanning helps identify such nests in fossil material? And what’s your take: should researchers actively search more caves for hidden bee nests, or focus on confirming the species involved in this case?
