When you think of bees, you might picture large hives bustling with activity. However, about 90% of bee species are solitary creatures. They often nest in the ground, decaying wood, or plant stems rather than creating those elaborate hives.
Recently, researchers made a surprising find in a limestone cave on Hispaniola, a Caribbean island. They discovered tiny, ancient bee nests built inside the tooth sockets of fossilized bones, some belonging to extinct animals. This unique discovery is the first of its kind, showing that bees can utilize bones as nesting sites, as detailed in a recent study published in Royal Society Open Science.
Lead author Lázaro Viñola-López, a postdoctoral researcher at the Field Museum of Natural History, expressed excitement over this unexpected find. “Usually, we find only rodents and birds in this cave, and not much about insects. To find evidence of ancient bees here was thrilling,” he said.
This discovery fills an important gap in the fossil record. Previous bee fossils from the Caribbean were found in amber and dated back around 20 million years, while the new findings are believed to be only about 20,000 years old.
Viñola-López and his team aim to understand more about the ecology of these island bees. He noted, “We need to look closer at specimens, as they can reveal unique behaviors of species we think we know well.” He believes that these nests showcase a wide range of nesting behaviors in bees, sometimes even exceeding what we consider typical.
The cave itself is a treasure trove of fossils, holding remnants from over 50 species, including ancient birds and reptiles. It is thought that barn owls may have inhabited the cave and deposited bones from their prey, which later fossilized. Additionally, the enclosed environment helped preserve these fascinating specimens.
During the exploration in the summer of 2022, Viñola-López closely examined the fossils and noticed something unusual: dirt inside the tooth sockets resembled how wasps construct their cocoons. After scanning the nests with advanced technology, the research team verified that they were indeed bee nests made of mud, differing from wasp nests that use a mix of saliva and plant material.
“Nesting in a cave is quite rare for bees,” said Viñola-López. According to the Florida Museum of Natural History, only one other instance of this behavior is known. He noted that multiple generations of bees seemed to return to the same spot for nesting, suggesting communal behavior.
Though the cave preserved the nests well, it wasn’t conducive to maintaining the bodies of the insects themselves. As a result, researchers haven’t yet determined the specific species involved. The nests are now classified as Osnidum almontei, named in honor of Juan Almonte Milan, who discovered the cave.
Stephen Hasiotis, a geology professor at the University of Kansas, commented on the significance of tracing the hidden biodiversity revealed by the study. “Even without the actual bee fossils, the traces left behind tell us key details about their environment and ecosystem,” he explained.
Moreover, Hasiotis believes the cave’s stable humidity likely attracted bees, providing shelter from heavy rains and predators.
“This discovery reminds us how adaptable insects are,” said Anthony Martin, a professor at Emory University, reflecting on the evolution of species over millions of years. “Bees will always find a way to survive and thrive,” he added. Both experts stressed the need for ongoing research to see if similar behaviors are found in other caves or regions.
