The bees were found among rocks near Portugal’s Atlantic coast. Researchers have identified fossilized “bulb-like” objects that they describe as traces of ancient cocoons. Because such nests may have been dug by many species of bees or wasps, the researchers initially thought they would never know exactly which insects lived here. However, they later discovered several intact and even sealed cocoons.

What scientists have learned

Scanning the samples, the team was able to spot the remains of ancient bees hidden inside these cocoons, which appeared surprisingly undeformed as they had been lying underground for thousands of years. Because the samples were robust enough, researchers recognized them as Eucerini, a group of bees with extremely long antennae.

Samples also include: Pollen traces obtained from plants belonging to the Brassicaceae (Cabbage) family; this suggests that these bees may have fed on it shortly before his death. About 3,000 plants belong to this species, including cabbage, radish, radish, mustard, horseradish and buckwheat. Presumably, the researchers were unable to identify a specific name.

Mummified bee / Photo: Andrea Baucon., Faculty of Science, University of Lisbon

Mummified bee / Photo: Andrea Baucon., Faculty of Science, University of Lisbon

These bees lay their eggs in underground burrows; Here, the broods spin cocoons over time and turn into adult bees before they rise above the ground. However, these individuals were killed before reaching this stage.

How did they die? The researchers suggested that all the bees may have died at the same time, due to sudden frost or flooding and subsequent burial. These conditions may have created a special, oxygen-free environment around the bees, which could inhibit the growth of bacteria that normally help the insects’ bodies decompose after they die. We can see something similar in prehistoric amber, some of which have insects in them.

X-ray image of drone inside the cocoon / Photograph: Federico Bernardini/ICTP, Faculty of Science, University of Lisbon

Cocoon scan / Photograph: Federico Bernardini/ICTP, Faculty of Science, University of Lisbon