Japanese Honeybees Deploy Swarm and ‘Roast’ Attack to Kill ‘Murder Hornets’ by Raising Body Temperature

Illustration - Chris Moody/Shutterstock

Americans already impacted by COVID-19 quarantine measures have yet another worry to deal with in recent weeks, after an invasive species of hornet was discovered in Washington state with the potential to do harm.

The Asian hornet (Vespa mandarinia), recently dubbed the “murder hornet,” threatens Western honeybees (Apis mellifera), which are already on the decline in the United States. Just a handful of the invasive hornets are capable of wiping out an entire honeybee hive, killing thousands of bees and then feasting on their larva. This threat has prompted the state Department of Agriculture to seek eradication of the species of hornet from the area.

It’s interesting to note, however, that not all types of honeybee are helpless in the face of a hornet attack. It turns out that Japanese honeybees (Apis cerana japonica) have an incredible adaptation that allows them to gang up and murder the murder hornet, which Western honeybees do not have.

Washington State Department of Agriculture entomologist Chris Looney displays a dead Asian giant hornet, a sample sent from Japan and brought in for research, on May 7, 2020, in Blaine, Washington. ELAINE THOMPSON/POOL/AFP via Getty Images

Washington State Department of Agriculture entomologist Chris Looney eyes a trap he retrieved, set in an effort to locate the Asian giant hornet on May 7, 2020, in Blaine,Washington. ELAINE THOMPSON/POOL/AFP via Getty Images

Footage from a National Geographic documentary shows how Japanese honeybees swarm an invading hornet; and using a special technique where they vibrate in unison, the bees are able to raise the temperature of the hornet and literally roast it alive.

The documentary explains how scout Asian hornets mark beehives with a telltale pheromone so that other hornets can locate it later on. But just as the hornet is about to take off from the hive, the Japanese honeybees, having signaled their plans to each other by wiggling their abdomens in a certain way, swarm and completely envelope the intruder without warning.

The bees do not sting the hornet, which would cost them their own lives, but rather, they begin to vibrate, raising their collective temperature to around 117 degrees Fahrenheit (47 degrees Celsius), which is just barely what the Japanese honeybees can survive, but which is just hot enough to kill the hornet. With the scout destroyed, the beehive remains safe from the hornet’s fellow comrades.

Beekeepers in the United States, who work with Western honeybees, are incredibly concerned that the murder hornet could spread from the Pacific Northwest to other areas of the country. Unlike their Japanese counterparts, Western honeybees have no defenses against the invasive hornet species.

Bees are seen on a frame at the rooftop bee hives of the Ginza Honey Bee Project on June 17, 2014 in Tokyo, Japan. Chris McGrath/Getty Images

In a study published in PLOS One, Japanese scientists have studied their robust native honeybee and identified the area of the bee’s brain they believe is responsible for helping it know how to increase their heat in a swarm and what temperature to stop at.

“It’s a pretty large area involved in learning; memory; and processing light, taste, smell and all kinds of other sensory cues,” says University of Arizona neuroscientist Wulfi Gronenberg, National Geographic reported.

This same area of the brain is active for Western honeybees, but not in the same way. “These hornets go and rob honeybee colonies and the [Western] bees have no chance,” Gronenberg adds. “They can’t sting through them. These hornets can bring down entire colonies.”

Japanese honeybees, originally believed to have migrated from the Korean peninsula, have greater cold hardiness and are more efficient honey producers than their Western counterparts.