Honeybee mobs overpower hornets

Japanese giant hornets, which can be up to 5cm long, are voracious predators that can devastate bees' nests and consume their larvae.

But, if the bees spot their attacker in time, they mount a powerful defence in the form of a bee ball.

As the temperature inside the ball increased to more than 45C, the carbon dioxide level also rose sharply.

"The hornet may be killed during the first 0-5 minute period, in which the highest level of heat production and carbon dioxide emissions take place," said Dr Sakamoto.