Wikipedia:
"When an A. cerana hive is invaded by the Japanese giant hornet (Vespa mandarinia)(also the Asian Hornet), about 500 Japanese honey bees (A. cerana japonica) surround the hornet and vibrate their flight muscles until the temperature is raised to 47 °C (117 °F), heating the hornet to death, but keeping the temperature still under their own lethal limit (48–50 °C)."