Nature’s Oddities Part 6: Giant Asian Hornet

Vespa mandarinia, also know as the Yak Killer Hornet (which gives you an idea of its sting), is perhaps the most ferocious and excellent killing machine nature has brought to bear. My friends know that I am quite fond of violent and predatory arthropods, particularly giant Amazonian centipedes, camel spiders, and scorpions. I am telling you, none stand a chance against the mandarinia.



30-40 Japanese are killed every year by these hornets, which is close to the annual homicide rate of Japan. Japanese children are warned of their dangers in much the same way American children are warned of “stranger danger.” The world expert on mandarinia, Dr. Masoto Ono, compared their sting to a 15-inch flaming hot nail. But most fearsome of all are their awesome (and that is a word I do not through around lightly) mandibles.



These mandibles are used to crush helpless victims with wanton abandonment. It is not unheard of for a single mandarinia to ruthlessly slaughter an entire hive (usually around 30,000 individuals) of European honeybees, Apis mellifera, which are fairly soldierly critters themselves. Can you imagine one human solider (Rambo, perhaps) subduing an entire army of other soldiers armed only with his fists and teeth? That is the daily life of the mandarinia!

I have seen footage of a honeybee hive being raided by just two mandarinia. All individuals (around 10,000) were killed before the rest of the mandarinia sisters (hives are around one hundred individuals) could arrive. But when they did arrive, they feasted upon the tender larvae and pupae of the honeybees until they became gorged and intoxicated and flew like drunks back to their own hive.

The most remarkable ability of the mandarinia is its adept use of all of its body. It possesses finesse unmatched by any predator I have seen. It makes cougars and even mongooses look clumsy by comparison. It easily dispatches 5-10 attacking honeybees (in a single second) with gentle movements from its legs and swiftly crushes their bodies’ whole between its mandibles. It flies gently left and right with noticeable confidence, and hardly ever has to use its sting. Mandarinia can subdue with ease critters several times their size, including birds and small mammals. The mandarinia is so powerful they seldom are caught in spider webs, but when they do get caught, the spider will probably be defeated. The mandarinia's exoskeleton is armored with chitionous plates so thick many spider fangs cannot penetrate.

I am positive that no scorpion, camel spider, or centipede could stand a chance against a single mandarinia (well, maybe the centipede has a chance). They are too slow and sluggish and simply do not have the firepower. Even insectivorous birds fly with fear when the mandarinia comes out. Often they cannot outrun them however, mandarinia can fly at 25 MPH.



A single mandarinia is formidable, now imagine 20-100 of them fighting in remarkable coordination like a well-trained platoon of soldiers, and you will understand why they deserve a place in the cannon of oddities. The pheromone signaling mechanism used by mandarinia is incredibly sensitive and complex, and is the focus of many Japanese entomologist’s careers. Most of them are trying to figure out ways to trick the mandarinia and keep them out of places where people eat, since mandarinia love sweet drinks, which are popular in Japanese outdoor cafes.

There is only one animal (other than homo sapiens) capable of subduing the mandarinia--the Japanese honeybee, Apis cerana japonica, which is almost identical to the European honeybee. When a mandarinia scout locates the entrance to a honeybee hive, it dances around the entrance secreting a pheromone trail that will summon her sisters. As the pheromone wafts through the air, a few minutes will pass before her battle sisters will arrive, and in the meantime the mandarinia explores the entrance often slaughtering a few hundred bees along the way.

European honeybees immediately attack the mandarinia once she is detected and attack in groups of 1-10, which the mandarinia dispatches as easily as I dispatch M&Ms, and the attack is completely ineffectual. The Japanese honeybee is wiser. It waits for the mandarinia to enter the hive (which is much warmer), and once the mandarinia is completely inside they form a compact ball around the mandarinia. The honeybees do not bother stinging or biting, since it would be useless against the mandarinia. Once the ball of hundreds of honeybees is formed they begin to rapidly pulse their flight muscles and raise their body temperatures to around 117 F. Meanwhile the mandarinia is slaughtering the bees near it at a rate of perhaps five bees every second, so other honeybees need to constantly join the ball for their fallen sisters. Eventually the mandarinia expires from heat exhaustion. Apparently the only weakness of the mandarinia is low heat tolerance (its maximum survivable temperature for more than a few seconds is only 113 F). So after a few minutes and several hundred honeybees, the mandarinia is defeated. Often the mandarinia's sisters start arriving, but turn away from the nest since they cannot find their sister. So, though cooperation and self-sacrifice the honeybees are able to save their colony. This behavior I find remarkable in itself, and I will pick a social insect in next oddities series.



Unlike most people, I feel empathy for insects. In the video about mandarinia I remember quite vividly a close-up of a honeybee that was buried in the ball. Its head had been severed from its thorax and its jaws and antenna were twitching in agony, and at that moment the narrator said in a low voice, “a though heroic sacrifice the honeybees sisters were able to save their hive, but it came with a price.”

In Japan mandarinia are thought to possess magical powers and their bodies are often crushed and added to energy drinks. In rural, backwoods Japan locals make fried hornets and sometimes eat them raw in a sort of hornet sashimi.