The Asian giant hornet — Vespa mandarinia — is a very-large species of venomous hornet, the largest in the world in fact. On average, they measure about 50 mm, with a 76 mm wingspan. They are known for their relatively large size, aggressive predatory nature, their ability to decimate honey bee colonies, and their extreme speed.
The animals are present throughout much of East Asia, but are especially common in Japan — home to the subspecies Vespa mandarinia japonica. Other regions which feature notable populations are: Eastern Russia, Korea, China, India, Nepal, Sri Lanka, Indochina, and Taiwan.
They possess a stinger which is about 6 mm in length — which injects a very potent venom, containing “a cytolytic peptide (in particular, a mastoparan) that can damage tissue by stimulating phospholipase action, in addition to its own intrinsic phospholipase,” as Wikipedia notes. Being stung by one — according to some accounts — feels a lot like having a hot nail hammered into you.
What’s crazy though — is that every year in Japan, where they are common, the hornets kill 30-40 people. That’s 30-40 people. Every year. Just in Japan.
If you want to get a stronger idea of their nature, read this:
The hornets often attack hives to obtain the honey bee larvae as food for their own larvae. A single scout, sometimes two or three, will cautiously approach the hive, producing pheromones to lead its nest-mates to the hive. The hornets can devastate a colony of honey bees: a single hornet can kill as many as 40 honey bees per minute thanks to its large mandibles which can quickly strike and decapitate a bee. The honeybee stings are ineffective because the hornets are five times the size and too heavily armoured. It takes only relatively few of these hornets (under 50) a few hours to exterminate a colony of tens of thousands of bees. After butchering the bees with impunity, the hornets loot the honey and carry off the bee larvae as food for their own larvae. The hornets can fly up to 62 miles in a single day, at speeds of up to 25 mph.
But there is something rather strange to note about all of this intensely predatory behavior — they can’t actually eat and digest the insects that they kill, they have to first get their larvae to eat and digest the food, then spit it back up. The larvae produce this “spit up” — vespa amino acid mixture — on demand, whenever the adults need to eat.
Asian honeybees aren’t completely helpless against these hornets though (European honeybees are), they do have a very effective strategy to combat them.
Although a handful of Asian giant hornets can easily defeat the uncoordinated defenses of a honey bee colony, the Japanese honey bee has evolved an effective strategy. When a hornet scout locates and approaches a Japanese honey bee hive she emits specific pheromonal hunting signals. When the Japanese honey bees detect these pheromones, a hundred or so will gather near the entrance of the nest and set up a trap, keeping the entrance open. This permits the hornet to enter the hive. As the hornet enters, a mob of hundreds of honey bees surrounds it in a ball, completely covering it and preventing it from reacting effectively. The bees violently vibrate their flight muscles in much the same way as they do to heat the hive in cold conditions. This raises the temperature in the ball to the critical temperature of 115 °F. In addition, the exertions of the honey bees raise the level of carbon dioxide in the ball. At that concentration of CO2, the honey bees can tolerate up to 122 °F, but the hornet cannot survive the combination of a temperature of 115 °F and high carbon dioxide level. Some bees do die along with the intruder, much as happens when they attack other intruders with their stings, but by killing the hornet scout they prevent it from summoning reinforcements that would wipe out the entire colony.
As far as the life cycle of the species goes, it’s rather interesting — depending on the latitude and climate they may follow the typical hornet life cycle of born-in-the-spring-die-in-the-fall, or they may live longer, as some tropical species do.
In closing, it’s probably worth noting that I’ve heard that in recent years some individuals in the US have started keeping the hornets as pets… That actually wouldn’t surprise me….