Japanese hornets

March 16, 2012 • 1:56 pm

Via Matthew Cobb and Ed Yong, here are a handful of (dead) queens of the Japanese hornet, Vespa mandarina, the largest wasp in the world. In a previous post on this species, I described how they attack and completely destroy bee colonies by decapitating the workers, and how the bees defend themselves by surrounding the wasp scouts, cooking the wasps to death by vibrating their bodies to generate heat. Both the wasps’ predation and the bees’ defense are impressive adaptations, ones that I used to begin the chapter on natural selection in Why Evolution is True.  If you haven’t read my earlier post, do so, as it includes two amazing videos showing a wasp raid on a bee colony and the “bee ball” defense.

The photo was taken by Addicted2Hymenoptera 🙂, who apparently bought these queens from a commercial outfit, insectsale.com. (I don’t recommend buying such stuff.)

Look at the size of those things!  Their stings kill several dozen Asians every year. (Of course it’s the workers, not the queens, who do most of the stinging.)

35 thoughts on “Japanese hornets

      1. Is this species rare enough? I imagine they’re killed whenever nests are found around habitations, because they regularly kill people. People in the US rarely put up with the presence of regular wasps and hornets on their land, and very very few would tolerate hornets of this size.

  1. Yes, a highly memorable part of your book, JAC, re: the bees’ defence mechanism, which I explained to work colleagues, to their amazement. Thanks for posting the astonishing picture; I fear it will give my 11 year-old nightmares! Bonsoir.

    1. This is a ridiculous statement. Nature is not all sunshine and butterflies.

      Predators such as this typically have an important biological role in population control.

  2. “Their stings kill several dozen Asians every year.”

    I am curious; is this because the subjects where allergic to the stings, or was it because they where swarmed, or is it infact their stings are particularly toxic? Or a combination of any two or all of these factors?

    …anyways, I don’t think I have to mention that those things would scare the hell out of me if I saw them live and active, even if the workers where only half the size of their queens pictured.

  3. from Wikipedia:

    ‘The sting of the Asian giant hornet is about 6 mm (¼ in) in length,[3] and injects an especially potent venom that contains, like many bee and wasp venoms, a cytolytic peptide (specifically, a mastoparan) that can damage tissue by stimulating phospholipase action,[4] in addition to its own intrinsic phospholipase.[5] Masato Ono, an entomologist at Tamagawa University near Tokyo, described the sensation as feeling “like a hot nail being driven into my leg”.[3]
    An allergic human stung by the giant hornet may die from an allergic reaction to the venom, but the venom contains a neurotoxin called mandaratoxin (MDTX),[6] a single-chain polypeptide with a molecular weight of approximately 20,000 u,[7] which can be lethal even to people who are not allergic if the dose is sufficient. Each year in Japan, the human death toll caused by Asian giant hornet stings is significant.’

    My wife was stung a couple of years ago (only once fortunately) by a worker from a nest made by the smaller variety of Japanese hornet (suzume-bachi – or ‘sparrow wasp’ – the big ones are called oo-suzume-bachi); nests are made extremely rapidly in autumn, and this had been made unbeknownst to us in a cover for an electricity metre in the passage alongside our house: my wife happened to brush against it. The workers will pursue you to quite a distance if they feel their nest is endangered; so far as I know almost anyone will die of heart failure after being stung only a few times.

    Away from the nest there’s small problem: suzume-bachi will go about their business and ignore large creatures like humans.

    1. I went back to the Wikipedia entry and from there to a Japanese report on allergy deaths in 2003, which listed 24 deaths as being due to bee-like insects, including the giant hornet, but also including honeybees.

  4. Flamethrower plz. ◉_◉

    I wonder how long these live, and if any brave/crazy soul has attempted to keep one as a pet.

    Wikipedia says the “hornets do not eat their prey, but chew them into a paste and feed them to their larvae. The larvae produce a clear liquid, vespa amino acid mixture, which the adults consume…”


      1. Oh, while I definitely find things like this fascinating, if I had to chew my food and spit it into my child’s mouth so they could eat it and later excrete a liquid I could consume and actually digest… I’m going to stick with “ick”, thanks!

        Better Vespa mandarinia than me. Just sayin’… 😉

  5. Awful thought ….What if one could synthesise the pheromone!

    Silly thought…. all dat radiasion iss gunna make em worse “mutant japanese wasp decapitates hiker”

  6. How people can possibly call animals gross is beyond me.

    Especially something as spectacular as this.

    Redefine your standards, guys.

    1. Ghastly; “Inspiring shock, revulsion, or horror by or as if by suggesting death; terrifying.” I stand by my adjective.

  7. I was on my roof yesterday and went near a small wasp nest.
    5 wasps flew at me and stung me on one ear and one finger.
    As someone mentioned, it is a very hot feeling and lasted about 10 minutes.
    I get a lot of wasps here and so had some wasp spray.
    It’s very good stuff.
    It kills any wasps it hits and any in the nest.

  8. I remember that bit in WEIT. It’s amazing and yet ever so horrible… How people can think of some ‘nice guy’ God when nature is so cruel and barbaric in its ways just amazes me.

  9. I wonder if, in fact, the largest species of the genus Pepsis might be bigger than these queens? I don’t know how big the hand of the person in the picture is, but I have seen Pepsis wasps that are longer than MY hand is wide, at least.

  10. The largest wasp in the world can best be resolved by weight of the specimens. I haven’t seen conclusive proof that the Japanese hornet weighs more than a female cicada killer, or a tarantula hawk. Individual specimens will vary, but what is the average? The tarantula hawk has the longest legs of any wasp, the cicada killer is the champ for flying power, it carries a large payload relative to its size and cannot be singed on the wing by use of a large torch (try it, I failed many times).

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