It is likely to be the first documented instance in nature of one animal systematically killing another by using its own body temperature.
Scientists have witnessed the baking execution in the Japanese honey- bee when it defends its hive against predatory giant hornets, which are several times bigger and capable of killing up to 40 bees a minute.
Thermal images, published in the journal Nature today, show that up to 500 bees surround a solitary hornet, raising its body temperature to a lethal 47 degrees, a few degrees short of the 50-degree heat that would kill the honey-bees. It can take up to 20 minutes before the defenders raise the temperature sufficiently to kill the hornet.
Scientists had previously believed that when a hornet was mobbed in this way, the honey-bees were stinging it to death.
The discovery was made by Massato Ono and colleagues in the entomology laboratory at Tamagawa University, Tokyo.