Bees produce shimmering waves for defense purposes, especially against hornets. Dozens of honeybees would sit on a hive and all flip their abdomens up in the air at the same time. Each flip lasted less than a second. This made the hive look like it was shimmering, or moving in a way similar to people doing “the wave” at a football game. If a hornet was not present, only a few bees would perform the shimmer. But if a hornet was nearby, almost all the bees in the hive would show the behavior. …if the hornet was flying more quickly than usual at the hive, more bees would shimmer more often. (Source)
