Bombardier beetle: Up close, in action

This is a great, clear video showing the defense mechanism of a wonderful, little creature. The bombardier beetle is a catch-all name for 500-odd related species of beetle that have a nifty, chemical-warfare defense mechanism built into their rear ends. Basically, the beetles can make their own hydroquinone and hydrogen peroxide, store it in their abdomens and, when threatened, mix the two chemicals to create a potent, heat-generating reaction that forces a boiling, vile-smelling liquid out of the beetle —and into the face of whatever was bothering it.

I was first introduced to the bombardier beetle in high school biology class. See, I went to fundamentalist Baptist high school, and the bombardier beetle is often trotted out as an example of something so complex, that it couldn't have possibly evolved. (I was also given the impression that this was just one, single type of beetle, rather than an array of varying, related beetles that produce and expel chemicals in slightly different ways. But that's not really the worst of the misleading and inaccurate things I learned in that biology class. Textbooks from Bob Jones University Press. I wish now that I still had the thing to scan pages.)

Anyway, I was told that "evolutionists" had no answer for how the bombardier beetle could have evolved. Naturally, that turns out to be bunk. As does much of what I was taught about how the beetle works. TalkOrigins explains the reality of both pretty well. With references! More fascinating, to me anyway, is the way the bombardier beetle actually fits with the predictions made by evolutionary theory:

Creationism, on the subject of design, says little except that similar forms were created for similar functions and different forms were created for different funtions, [Morris, 1985, p. 70] or, briefly, that form follows function. However, that does not describe the pattern we see in nature.

The same function often takes different forms. Many ground beetles have habits and habitats quite similar to centipedes, but the two groups look nothing alike. One group of bombardier beetles (the paussines) uses the same chemical mechanism to shoot their defensive spray as other bombardier beetles, but they have a totally different method of aiming. Brachinine bombardier beetles have their gland openings at the tip of their abdomen and simply bend their abdomen to aim; paussines have their gland openings more to the side, shoot from only the chamber on the desired side, and if they want to shoot forward, move their abdomen slightly so that the opening is adjacent to a flange on their elytra that deflects the ejecta forward. [Eisner and Aneshansley, 1982] Pygidial glands are used for defense not just by bombardier beetles but by virtually all beetles in the suborder Adephaga, but the structure of the glands and the chemicals they secrete vary significantly among different families and genera of beetles. [Forsyth, 1970; Kanehisa & Murase, 1977; Moore, 1979; Eisner et al., 1977]

The same form is sometimes used for different functions. I know of no good examples among bombardier beetles, but rove beetles show an example. Many species exude defensive chemicals from the tip of their abdomen. Beetles of the genus Stenus have another use for those chemicals. When threatened while foraging on water, they touch their abdominal glands to the surface of the water. The chemicals disrupt the surface tension, which rapidly propels the beetle up to several meters. [Eisner, 1970, p. 200]

Finally, some forms have no function. Some species of bombardier beetles (and many other insects, for that matter) cannot fly but still have vestigal flight wings. [Erwin, 1970, pp. 46, 55, 91, 114-115, 119] Some may argue that the wing stubs have an as yet unknown function, but even in the remote chance that functions can be found for all vestigal wings, the situation merely changes to the previous case of different functions for the same form.

Bombardier beetles on Wikipedia
Short piece on the beetles from the Ecological Society of America

The in-depth explanation/refutation of Creationist thought on the beetles by the good folks at TalkOrigins


  1. “and, when threatened, mix the two chemicals to create a potent, heat-generating reaction that forces a boiling, vile-smelling liquid out of the beetle —and into the face of whatever was bothering it.”

    I get a lot of complaints from the wife about this myself.

    I keep saying to her…it’s evolution…it’s a protective thing. I’m sure the beetles wife isn’t buying it either.

  2. I don’t see why they couldn’t have filmed shots of it using the defensive mechanism naturally instead of hot glueing(?) it to a stick and holding it in place so that the ants could climb on it.

    ~D. Walker

    1. It looked unrestrained in the earlier instances.

      But the glue is probably because it’s a huge chore to adjust a camera’s angle and focus on the fly at such a high magnification. Every tiny twitch or vibration shakes the viewfield around which of course ruins the video clarity until the movement stops.

    2. Probably because photographer time isn’t free, and following a beetle around, waiting for something to piss it off, could get tedious(and, when something does piss it off, the odds that you’ll have the focus just right are pretty dubious)?

      Misrepresenting staged shots as wild ones is dodgey; but staged shots are a vital, and extremely common, tool for investigating particular structures and behaviors in all sorts of organisms. Particularly if you need a touchy ultra-high frame rate camera, or a wind tunnel full of fine mist to allow optical turbulence tracking, or any of that other lab gear, traipsing around the woods, waiting for nature to do its thing is basically pointless and essentially impractical.

  3. As someone else who was forced to attend one of those Baptist schools that used BJU Press book I have to agree 100% that these beetles are the least of the mis-information given by the text. There was so much that was wrong in those books and they didn’t correct their mistakes between revisions either.

  4. It might be worth trading opposable thumbs for the ability to mix hydrogen peroxide and hydroquinone and shoot it (though preferably not out of one’s own bum).

    During fundamentalist high school I attended a lecture from someone associated with Answers in Genesis. At the talk he showed a slide of a whale and said, “Dead animals don’t evolve. You take a whale out of water, does it survive? No. Then how’d it walk on land? It didn’t. Dead animals don’t evolve.” Also, dude said that dragons were likely dinosaurs that were hunted to extinction. There may be some alive in the Congo though.

    1. Juvenile makers of pipe bombs often trade their opposing thumbs (and often the fingers that are opposed) for the ability to make a big kaboom.

      Most tend to regret the trade.

  5. In the slow motion replay at the end, the sound of the gas being released sounds, um, somewhat familiar.

  6. Great item.

    The story of how the beetle was touted as evidence of god but … um … wasn’t (religion is so bad at science!) reminds me of Darwin and Wallace’s predictions about the moth needed to pollinate long-necked orchids.

    (I assume the religious hypothesis was god did the pollination, not sure if this qualifies as a virgin birth.)

  7. Hydrogen peroxide is a component of rocket fuel, right? I wonder if this little beast could attain escape velocity. Will we find them on Mars and Titan?

    1. No, but millions of years in the future, they will become biological hand grenades. (No mention of Marooned in Realtime yet? Shame you you people!)

  8. I’m horrified that anyone had to attend a fundamentalist christian high school. I can only imagine what revisionist boloneyshit you were fed in history and lit classes in addition to biology. Did they even have earth science classes?

    1. Yeah, we had earth science classes. In MY fundie school, they were even called ‘Earth Science’. You know how Orwell wrote about this thing called NewSpeak? Yeah. Double-plus un-good, let me tell ya.

      I had to apologise to a lot of people when I grew up and realised what a shocking ass that material turned me into. I feel your pain, Maggie- I too was plunked down in front of AIG videos, among others.

      All I can say is that ‘there but for the grace of God go I’. Fortunately, my love of science led to my actually pursuing a path of honest investigation rather than the usual Christian M.O. of shrill repetition.

      And yes, I am quite happy to explain how one can be a Christian and an ‘evolutionist’ at the same time.

      1. Ditto, I went to several fundie schools myself up until I was kicked out of one in the 8th grade for bringing ZZ Top’s Eliminator album to school for a friend to borrow. I was considered a ‘bad kid’ and ‘too worldly’ to continue in their bastion of Christian education. Then they remembered I was a starter on all of their sports teams and begged my parents to bring me back…I less than politely declined. I can agree w/ you about being a Christian and believing in evolution as well. God created the universe and the laws that govern it. Why would He need to break the very laws He created to prove a theory put forth by man? Evolution makes sense. The fact that I am descended from an ape…not so much, but all theories have their flaws.

        1. Evolution makes sense. The fact that I am descended from an ape…not so much, but all theories have their flaws.

          FAIL! You are not special, even though you think digital watches are a pretty neat idea.

          Homo Sapians and Pan Troglodytes (our closest non-human primate relative) shared a common ancestor WAY back when. That common ancestor was NOT an “ape”.

          Indeed, go back far enough, and we all share a single common ancestor, a proto lizard with a mutation.

          Five digits on each paw. A trait we share with every mammal today and a LOT of cold blooded animals.

          Yes! MUTANT LIZARD HANDS! You have them!

          1. The common ancestor was too an ape. It was not any modern ape, but were it alive today, there’s no doubt we’d consider as such. Humans are closer to gorillas and chimps than any of the three are to orangutangs.

            The argument you’re using is, strangely enough, one that makes people more special – putting them to one side from the ape family. But really, we belong among them, just as we ultimately belong among reptiles and fish.

            Of course, your main point stands very well. jrhd has obviously never looked at other mammals in any great detail, if he thinks a theory predicting incredible similarity has made a mistake.

          2. Why do you try to put words in my mouth or thoughts in my mind? I never typed that I thought I was special nor did I type that I thought digital watches were a neat idea (quite on the contrary, I think they dumb our children down and don’t teach them to actually think and tell time). Why do you disparage and attack me personally because I don’t think exactly as you think? Expand your horizons and open your mind to views that are not the same as your own.

          3. Jrhd, I think Chris’s “digital watches” comment was a joke based on The Hitchhiker’s Guide to the Galaxy. In the first book of this series, when describing Earth, the narrator says that humans are “so amazingly primitive that they still think digital watches are a pretty neat idea.”

          4. But if you found a digital watch lying in a field, would you think it just appeared there naturally? Or would you think it was made by a creator? And if you found that creator, would you think he occurred naturally? Or would you think that the creator had a creator? And what about that creator’s creator? What kind of watch does *he* wear?

            Man, no wonder you hate watches.

          5. #37 jrhd

            Why do you disparage and attack me personally because I don’t think exactly as you think?

            You’re entitled to your own opinions, but not to your own facts.

    2. “I’m horrified that anyone had to attend a fundamentalist christian high school. I can only imagine what revisionist boloneyshit you were fed in history and lit classes in addition to biology. Did they even have earth science classes?”

      One of the most surreal experiences I had in high school was in my AP physics class, watching a video supporting the “young earth” creationism angle. It was introduced by a tiny, soft-spoken gnome of a man, the physics teacher, who presented it very shyly, with a fortuitous introduction essentially claiming that physics was black magic, and that, while we were learning its deep, dark secrets, we shouldn’t let our discoveries lead us to question the fact, revealed to us in The Bible, that the earth was only a few thousand years old.

      Getting fundie schooling really, paradoxically, instills in one a love for science. You all may have been learning boring old “physics.” I was learning black magic dark enough to shake the foundations of the only true belief system the world had ever known, and would ever know.

      It also instills in one a love for sex, but that’s a different blog post…

      1. “…in my AP physics class, watching a video supporting the “young earth” creationism angle.”

        WTF? Young earth creationism in physics class? That’s many levels of wrong.

        “…with a fortuitous introduction essentially claiming that physics was black magic…”

        I don’t think Isaac Newton shared that perception of physics.

        You have my condolences.

        1. Newton attributed many things he couldn’t figure out himself to be the work of God.

          Later, when someone figured out some of these things, they too eventually ran up to the limit of their knowledge… and beyond that point they saw things as the work of God.

          A lot of scientists in the past have basically attributed anything they understood to science and anything they didn’t to God.

          This is part of why fundamentalism bristles so much at the advance of science. It’s embarrassing to have other people step in, explain things you weren’t capable of understanding yourself, and demystifying the realm of God’s magic you had believed in. It’s more about personal pride than religious belief. Saving face takes precedent over reason.

  9. #13 — One of James White’s Sector General stories features a low-tech spacecraft that reached escape velocity through the efforts of lots and lots of (the alien equivalent of) bombardier beetles. Who, besides providing propulsion, are also the astronaut crew.

  10. A bug that farts acid. How cool is that!!

    PS. Congrats to all who survived the idiotic religious indoctrination with your critical thinking skills in tact. I only wish there were more of you.

  11. When I was in Nicaragua, I got little burns on my ankle, and the people there told me it was from a bug that shot acid. Now I know what it was!

  12. The Bombardier Beetle!
    When I was a kid my evangelical christian parents had a picture book about creationism.
    I can still remember the illustration of one of these little guys.
    I’d love to see that book now.

  13. Jeez, we’re a bunch of Jesus crispy spawn here, I’ll tell you what. I didn’t go to a fundie high school, I was home schooled due to some out of the country living and moving around at that age. But I did go to a fundie school through 8th grade. (Posters from Bob Jones U, videos on the perils of rock music including backwards masking, etc.)

    The strange thing is, they tend to be really good schools other than the touchy subject of evolution. The discipline was firm but reasonable, teachers were dedicated and generally very good, and the educational outcome was excellent except for evolution. The students almost invariably tested well ACT/SAT wise, and the vast majority went on to college. That may have had a lot to do with economic class, though, as being a private school with tuition the parents obviously had money. My dad was a preacher so we were the charity cases.

  14. Wow– so many of you went through heavy-duty Creationism indoctrination and managed to survive with your skepticism intact, which is pretty remarkable. I’d love to hear how you managed to accomplish that, because it can’t have been easy. Maggie? Anyone?

    1. “You have my condolences.”

      Aww, well, we read BB, now, so clearly, we got better. ;)

      ” I’d love to hear how you managed to accomplish that, because it can’t have been easy. Maggie? Anyone?”

      My experience (and it may have been unique) is that showing a bunch of rebellious teenagers stuff that claims to be not only the Truth, but also the reason that girl in your art class won’t sleep with you, leads to much more questioning then just ignoring the whole bag, and assuming that girl in art class was just a snooty bitch.

      I mean, what would you have done if you were 15, just figuring out independence, moving beyond “I’m the mom, that’s why!” and were handed “I’m the God, that’s why!” on a platter?

      Nah, I’m more worried about what happens these days, now that they’re trying to give fundie bible-thumping some sort of counterculture cachet with the whole “poor, persecuted Christians” angle and cross tattoos and whatever. It was easy to rebel against the majority as a teenager — that’s what teenagers DO! That’s probably when some BB readers started paths toward Atheism, no doubt. But when your rebellion is co-opted by chastity rings and hard-rock that hearts Jesus, it makes it seem like not believing in evolution is the edgy thing to do. That makes me a little more nervous.

      1. Don’t worry. None of the “hipness” the fundies are trying to inject into their scene isn’t even close to being hip. It’s cheezy, it’s cynical, and most intelligent teenagers that don’t have an over-developed desire to “belong” will see right through it.

        I have my worries about the victim complex, though. I’ll give you that.

  15. “something so complex, that it couldn’t have possibly evolved.”
    Sadly, the phrasing is much more subtle.. try something along the lines of: “We’re still too stupid to figure out how this damned bug managed to evolve this mechanism, Therefore God Exists.”

    Even more sadly, this very argument slides quite nicely into the old adage: “Ignorance Is Bliss”.

  16. Recently in Utah’s Zion National Park I was unexpectedly sprayed in the face by what turned out to be a bombardier-class beetle I picked up. Really nasty stinging sensation that felt like tiny fire ants. I immediately dropped the beetle.

  17. Yes, I know he was referring to HGttG…and I know the answer to the meaning of life is ’42’. What I find offensive is the fact that he didn’t posit it as a sly reference to a mildly amusing piece of science fiction. Instead he decided to take a pot shot at someone who doesn’t see the world as he sees it. That to me is close minded and trite. And from the sound of the other comments/replies BB is rife w/ close minded folk. I am not interested in proving you wrong or proving me right. I believe what I believe. You believe what you believe. I don’t call you names or disparage you for believing what you believe. I would ask you to extend the same courtesy. Does it make you feel better about your belief system to belittle someone who does not believe what you believe? At one point in the past it was believed that world was flat. That was proven false…we don’t know as much as we think we know and we don’t know for a fact all that we take as truth.

    1. I’m confused about your beliefs, though. You believe in evolution, but not that humans evolved from apes? Do you believe that humans evolved from something or were they created whole cloth with no ancestors common to other animals?

    2. Which you just typed with your MUTANT LIZARD HANDS!


      I KNOW I’m special, because I am made from stars. (Just as you were, by the way!)

      The iron in my blood, the calcium in my bones and all the other elements in my body were born in the novae and supernovae in this part of the universe that exploded, filling space with those elements.

      Somehow thinking that evolving from our common protoprimate ancestors is a flaw, how you disparage and disrespect them!

      They succeeded! They survived against incredible odds in a world where they were FOOD. They prevailed, they multiplied and were all but wiped out multiple times. And they EVOLVED. They got bigger and stronger and SMARTER. And they LIVED.

      They LIVED, and YOU and I and every other human on this planet are their heirs.

      Believe what you want. I’m proud of Lucy and Ardi and every other bipedal mammal that lived and fought and reproduced and evolved that is part of my bloodline.

      My ancestors kicked ass!

      1. “My ancestors kicked ass!”

        Kind of makes me feel a little guilty spending last night wanking off instead of fighting tigers, but I guess my forefathers died so that I may wank.

        And those lizards would probably be pretty impressed that their offspring can think of things that don’t actually exist.

        1. Civilization! That you can use your MUTANT LIZARD HANDS to wank off, instead of standing guard at the mouth of the cave with a pointed stick, that my friend is what civilization and evolution is all about.

          Opposable thumbs! Not JUST for holding bananas!

          (You hear that, Kirk Cameron! They’re NOT JUST FOR HOLDING BANANAS!)

  18. @jrhd – I second @dculberson (#41), if you believe in evolution like you claim, what did we evolve from pray tell, if not primates? Please do elucidate your opinion. People will continue to “put words in your mouth” unless you put some of your own. So far all we have from you is that you believe in evolution but not human evolution from primates. “Evolution makes sense. The fact that I am descended from an ape…not so much”. How one can believe one without the other is a mystery we’d all like explained. Pretty Please.

    @wylkyn (#39), @ManOnPinkCorner (#42), @ChrisTucker (#44) – 3 awesome posts, each brought a smile to my face. @wylkyn, thanks for pointing out the flaw in intelligent design in a humorous way. @ManOnPinkConter, thanks for pointing out the difference between opinion and fact. @ChrisTucker, our ancestors were indeed awesome.

  19. @jhrd: “At one point in the past it was believed that world was flat. That was proven false…”

    You choose a poor example to illustrate your point. The curvature of the earth (if you think of it as a sphere of circumference 25000 miles) is approximately 0.000126 per mile (which is close to 0 per mile). The people who thought the earth was flat were very nearly correct.

    However, the people who think that the earth was created by a magic being in the sky are almost certainly very wrong, because all the evidence of the world around us suggests we got here slowly, step by step, over a very long period of time.

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