The Japanese honey bee (Apis cerrana japonica) has evolved a unique defensive behavior to combat Japanese giant hornets (Vespa mandarinia). It’s a defensive behavior that has taken centuries if not eons to develop. In the picture above, we can see this formation, called a “bee ball,” which is enveloping two hornets.
Why is the Japanese honey bee hive targeted by the giant hornet?
Japanese giant hornets feed their larvae with protein garnered from the larvae or carcasses of other insects. As we know, honey bee hives don’t only contain honey and pollen – they also contain bees and also juicy fat larvae. Therefore, the aggressive giant hornets often attack honeybee hives to obtain honeybee larvae. The hornets are formidable killers, using their sharp talons and powerful mandibles to sever limbs and heads. European honeybees (Apis mellifera) have no answer for these predators. As a result, European honeybee hives are quickly decimated by the hornets. The hornets get into the hive and chew the honey bee larvae into a protein paste to give to their young hornet larvae.
How does the Japanese honey bee kill the Japanese giant hornet?
Unlike the European honey bee, the Japanese honey bee has a distinct defensive behavior in response to hornet predation. It’s a behavior that’s taken eons to develop. What happens is that if a hornet scout enters the hive, a group of Japanese honey bee will “ball” the hornet by swarming it. The effect of the swarming is to raise the temperature of the “ball” interior to 117ºF, a temperature lethal to the hornet, but not to the bees. The hornet is killed from overexposure to heat – it is in a manner of speaking, cooked to death. The Japanese honey bee hive is saved. It’s an incredible group defense mechanism reported in National Geographic.