Hornet cooked by bees

Beware the hot defensive bee ball

Honey bees should have no chance at all against the ferocious Japanese hornet – the predators are an inch long, and watching the two battle is like watching infantry racing hopelessly towards a tank. But the tiny creatures can actually triumph – by swarming over their foes in such numbers that hornets are ‘cooked’ inside a ball of bees. The defence mechanism is known as a ‘hot defensive bee ball’. When hornets attack, they kill all the worker bees, before ‘looting’ a nest for larvae and food. So the bees developed the defence mechanism to stop the predators. The bees swarm over the hornets in groups of up to 500, and start vibrating their wings until the temperature reaches 47 degrees centigrade. The heat is fatal for the hornets.

Researchers in Japan watched the bees as they assaulted an inch-long hornet – pulling them off the ball as they attacked and scanning their brains to see how they coordinated their attacks. The scientists, Takeo Kubo of the University of Tokyo and Masato Ono of Tamagawa University sampled bees at different points during the assault – and found that bees engage higher brain functions as they swarm into the ball. The bees coordinate their attacks, sharing information about heat in the ball – which could be a trigger for the bursts of brain activity.