Giant honey bee colony buzzing in sync

This 16 April 2019 video says about itself:

Massive Bee Colony Buzzing In Sync To Scare Off Predators | BBC Earth

These giant bees buzzing create spectacular waves.

Beekeepers across the United States lost 40.7 percent of their honey bee colonies from April 2018 to April 2019, according to preliminary results of the latest annual nationwide survey conducted by the University of Maryland-led nonprofit Bee Informed Partnership. The survey results indicate winter losses of 37.7 percent, which is the highest winter loss reported since the survey began 13 years ago and 8.9 percentage points higher than the survey average: here.