On August 21, 2017, crowds of people across the United States gathered to watch the moon pass before the sun. As the moon’s shadow passed directly overhead — totality — the sky went dark. And bees noticed.
People had set out microphones in flower patches at 11 sites in the path of the eclipse. The microphones picked up the buzzing sounds of bees flying among blooms. But those sounds were noticeably absent during the short period of the full solar blackout, a new study finds.
Before totality, light dimmed. The air also cooled a bit. This didn’t appear to affect the bees, however. Only the deep darkness of totality did. At that point, the buzzing shut down. Researchers described this buzz-out October 10 in the Annals of the Entomological Society of America. The change in buzzing at the time of totality was abrupt, notes Candace Galen. She is an ecologist at the University of Missouri in Columbia and author of the study.
The recordings come from citizen scientists, mostly school classes. They set out small microphones at two spots in Oregon, one in Idaho and eight in Missouri. Often when bees went silent at the peak of the eclipse, Galen says, “you can hear the people in the background going ‘ooo,’ ‘ahh’ or clapping.”
There’s no entirely reliable way (yet) of telling what types of bees had been buzzing, based only on their sounds, Galen says. She estimates that the Missouri sites had a lot of bumblebees. The Western sites had more of the tinier, temperature-fussy Megachile bees.
The temperature plunge in the Missouri summer just “made things feel a little more comfortable,” Galen recalls. But in the West, temperatures dropped by at least 10 degrees Celsius (18 degrees Fahrenheit).
As far as Galen knows, these buzz recordings gives the first formal data published on bees during a solar eclipse. “Insects are remarkably neglected,” she says. “Everybody wants to know what their dog and cat are doing during the eclipse. But they don’t think about the flea.”