Vespa mandarinia raids honey bee colonies, and a successful raid destroys the hive. The native Japanese honey bee has a counter. When a scouting hornet arrives, workers do not sting; they mob it, forming a tight ball of several hundred bees around the intruder and shivering their thoracic muscles.
The interior of the ball heats to roughly 46 degrees Celsius while carbon dioxide concentration rises. Bees tolerate that combination for the twenty minutes or so it takes; the hornet does not, and dies. The margin is narrow, which is why the behaviour depends on both heat and elevated carbon dioxide rather than temperature alone.
European honey bees are not defenceless, but they are outmatched. Apis mellifera colonies do mob hornets; their balls are smaller and cooler, the bees waste effort trying to sting, and the heat reached sits too close to their own limit to kill reliably. Hives in Asia are still destroyed, which is why the hornet threatens beekeeping. A population found in Washington State and British Columbia from 2019 was declared eradicated by the United States Department of Agriculture in December 2024.