In Japan, beekeepers often prefer European honey bees because they are more productive than the endemic Japanese honey bees. However, it is quite difficult to maintain a captive hive of European honey bees, as the hornets will often prey on the bees.
Once a Japanese giant hornet has located a hive of European honey bees it leaves pheromone markers around it that quickly attract nest-mates to converge on the hive. A single hornet can kill forty European honey bees in a minute; a group of 30 hornets can destroy an entire hive containing 30,000 bees in a little more than three hours. The hornets kill and dismember the bees, returning to their nest with the bee thoraxes, which they feed to their larvae, leaving heads and limbs behind; the bee larvae are also taken to feed the hornet larvae. The hornets also eat the bees’ honey.
The Japanese honey bee, however, has a defense against these attacks. When a hornet approaches the hive to release pheromones, the bee workers will retreat back to the hive, leaving an opening to allow the hornet scout to enter. At a given point, the bees emerge from their hiding places in an angry cloud formation containing some 500 individuals. They form a tight ball around the hornet that acts like a convection oven when the bees vibrate their wings to direct air over their bodies, warmed by their muscular exertion, into the inside of the ball. The interior temperature of the ball rises to 47 °C (117 °F). The hornet can survive maximum temperatures of 44–46 °C (111–115 °F), but the bees can survive up to 48–50 °C (118–122 °F), so the hornet is killed and the bees survive.