There has been a lot of news about the invasion of Asian giant hornets in the northwestern USA and western Canada, the UK, and Europe recently. Giant honeybees in Asia have had to live with such deadly predators for hundreds of years, and have developed a superior defense against potential invasions.
Giant honeybees are capable of an amazing phenomenon which biologists call shimmering or a Mexican wave. They do this to defend their hives. For a human observer this collective defensive behavior is an awe-inspiring display that demonstrates the unity consciousness of the hive-mates.
Here are two short but riveting videos of bees shimmering, or doing the Mexican wave.
BBC Earth footage, 2-minutes long, incredible In Sync Shimmering:
When the hive is attacked by a predator, a large group of bees gather on the surface of their colony and in a time-sequence ripple effect formation they flip their abdomens upward. This creates a shimmering ripple, somewhat like the Mexican wave in a football stadium.
Humans are mesmerized by the visual rippling wave as we see the individual parts of the super organism become as One.
Aggressive giant honeybees are about an inch long, and they live in the forests of countries like Vietnam in east Asia. These bees are considered to be some of the most dangerous of stinging insects. When they come together to build a nest it measures a few meters across.
They repel invasion of their nest by thieving birds or mammals by aggressively mobilizing a swarm of defenders within seconds. Asian hornets and wasps are so big they make the giant bees look small. The bees use their subtle and surprising defense against these aggressors. The technical term for the Mexican wave is shimmering.
Honeybees Mesmerizing Defensive Wave by Viral Hog is 2:53-minutes long:
Some hornets and wasps invade hives while others act like bombers that snatch away bees from the surface of the colony. National Geographic says this is called bee-hawking. Since the bee nests are open areas covered with many workers, these are very vulnerable to this form of wasp piracy.
But the hornet will get more than it bargained for, since the worker bees have a plan called ‘shimmering.’ As the hornets approach, the worker bees will individually raise up their bottoms to a 90° angle and shake them in sync. One after the other the worker bees join in as the movement builds into a hypnotic rippling booty-waggling and shaking event that covers the entire hive. This natural event is awe-inspiring to watch.
It’s the abdomen that does the shimmering. The bees signal to each other to hold formation. They communicate by scent. After a few ripples, shimmering worker bees release the chemical Nasonov pheromone from an abdominal gland. This smell tells the other bees to stay together, so guard bees won’t break rank and fly off to attack the hornets.
Gerald Kastberger from the University of Graz in Austria, along with Evelyn Schmelzer and Ilse Kranner, have provided the first proof of the long-held belief that shimmering is an anti-hornet measure. They have spent 15 years observing these giant bees in the wild in both India and Nepal and have video-recorded and analyzed the behavior of two giant bee colonies in Nepal. This study was the culmination of their work.
Their videos conclusively reveal that there are two types of shimmering—small scale and hive-wide. Small scale is a normal occurrence that causes predators to veer wildly off course and involves only up to 10 bees. The hive-wide shimmering involves hundreds of bees spread over the surface of their nest and is reserved for when hornets and wasps come within range. The bigger the threat, the stronger the shimmer.
The objective is to build a defensive zone of about 50 cm around the circumference of the nest. The closer the wasps get, and the faster the threatening hornets fly, the more bees join the lines of defense to strengthen it. Hovering hornets, if they cross the ‘invisible line’ are subjected to stronger rippling waves. As soon as the shimmering begins, predators grow irritated, stop their attacks and fly away. If they fly faster, they miss their mark. The more bees that join the shimmer, the faster the hornets withdraw.
How the shimmer works isn’t clear. Kastberger thinks the small-scale wave may create a challenge for a wasp or hornet to focus on any one bee. Large-scale shimmers threaten the hornets.
As a defense option, shimmering has many positive attributes for the giant bees. It takes very little energy to gather in a group and moon the hornets. Shimmering doesn’t cause the bees to actually engage with their more powerful enemies, so it is largely risk-free. It is a highly effective defense. Kastberger never saw the hornets take even one bee from the nest’s surface after observing hundreds of attempted attacks in a 30-minute period. The only time the hornets could successfully catch the giant bees in mid-air was when they left to go foraging.
What can we take from this amazing spectacle? That nature in general and bees specifically are highly intelligent... we are also reminded of the saying, united we stand, divided we fall.