The ultimate in camouflage?

by Matthew Cobb

Over at Myrmecos, Alex Wild has published this picture by William Piel and Antonia Monteiro of this amazing moth, Macrocilix maia, which lives in Malaysia and Borneo. This is a kind of Rorschach test. What do you see?

photo: William Piel & Antonia Monteiro

On his Flickr stream, Allan Lee published another photo and writes: “The pattern looks like 2 flies approaching some bird dung. As my friend have highlighted, we notice that there’s a bad smell emitted by this moth. This is really an interesting moth trying to fool it’s predators by both sight and smell.”

You can find other Flickr pictures of M. maia here.

On Twitter, Alex (@Myrmecos) and Ed Yong (@edyong209)  had a discussion about whether this pattern is indeed ‘meant’ to show a pair of flies. Ed wondered whether Alex was reading too much into it, to which Alex replied “The full flickr collection of this species won me over”.

It certainly looks to me like a fly – what species?! 😉  – and presumably there are a pair of flies here because the genetics of butterfly wings makes it very difficult not to be symmetrical.

However, there is a much bigger issue here. What is the adaptive value of looking like something else that could be eaten, like a fly? Or even worse, a pair of flies? OK, if the “flies” were attacked, then the moth might only get its wings damaged, rather than its body. But that would still be a substantial cost. And surely the added smell would attract either real flies, or predators on flies… It’s an odd story. As Alex says, this is a PhD project just crying out for funding, a bold supervisor and an intrepid student.

[EDIT: Try walking away from your computer screen (not yet, you ninny) and looking at the image from a few metres away. Now it most definitely looks like flies (especially the left hand one). But why?]

[EDIT 2: Antonia Monteiro mailed me, giving me permission to reproduce the photo and saying: “Yes, this moth is quite extraordinary. Bill and I also wrote a small note in a Yale internal magazine about it. It contains precise coordinates as well as the names of the people that helped us identify this moth.”]


  1. Joe Hern
    Posted August 31, 2011 at 3:30 am | Permalink

    1. Are we certain all bad smells to humans also attract flies?

    2. Perhaps the design is “meant” to look like something rancid or sick, not necessarily dung.

  2. Sidd
    Posted August 31, 2011 at 4:26 am | Permalink

    Do we know specifically what the pair of “flies” are supposed to be? Perhaps they look like a species of highly poisonous insects. For example the red part could depict a weaponized laser, and we all know that predators avoid laser-equipped prey. Metaphorically, of course.

    • sponge bob
      Posted September 2, 2011 at 5:20 pm | Permalink

      I don’t know, but someone needs to figure this mimicry stuff out. This one is particularily ‘creepy’.

      I’m thinking there is some interaction with the environment going on… and I don’t mean the natural selection/mutation type of interaction… I’m talking some type of gene exchange or something between plants and insects… and other insects.

      Leaf and stick insects are extremely good at mimicry. Too good, imho.

      Anyone ever looked into retroviruses and horizontal gene transfer between plants and insects?

  3. Posted August 31, 2011 at 4:26 am | Permalink

    Is the main predator birds ?

    Birds have four types of colour receptors in the eye, unlike us mere mammals with two or three types. It might be illuminating (sorry) to capture images that go from red right up through the UV part of the spectrum. Also perhaps polarised light if moths have the tiny scales found on butterfly wings.

  4. Marcus Stensmyr
    Posted August 31, 2011 at 4:41 am | Permalink

    Truly remarkable! The flies look like Muscidae, which would fit with the poo mimicry. The smell though is a bit weird. I assume that is a defense compound, rather than part of the mimicry. Bird poo doesnt usually smell that much, or?

    • Dominic
      Posted August 31, 2011 at 5:54 am | Permalink

      Bird doo can do – smell that is. Once when I was working at Chichester Cathedral I had to clear long amassed guano out of a roof space above the north aisle. It was 2 feet think in places & full of dessicated dead birds as well – the stench was ammonia probably.

      It really is a beautiful moth, at the risk of being ‘lookist’!.

  5. Jonathan Smith
    Posted August 31, 2011 at 4:51 am | Permalink

    No,No I see Jesus on the left wing and the Virgin Mary on the right.

  6. AdamK
    Posted August 31, 2011 at 4:53 am | Permalink

    Maybe they’re “meant” to be some sort of stinging insect, like wasps/hornets.

  7. Posted August 31, 2011 at 5:02 am | Permalink


  8. Physicalist
    Posted August 31, 2011 at 5:22 am | Permalink

    Bugs splattered in caramel on flower petals.

    Seems like haute cuisine — more of a suicide plan than camouflage, I’d say

  9. Maverick
    Posted August 31, 2011 at 5:23 am | Permalink

    Do the bad smell and images of flies attract other flies?

  10. James C. Trager
    Posted August 31, 2011 at 6:11 am | Permalink

    I see two calliphorid (flesh) fly patterns. The females lay live maggots on carrion and on infected wounds of vertebrates, and the eating of them can result in myasis (maggots in the gut), so hardly to be considered highly edible fare, perhaps.

  11. Chris
    Posted August 31, 2011 at 6:44 am | Permalink

    Clearly it is Jesus, wearing boxing gloves and all aglow, his arms raised in triumph after handing out yet another holy beat-down.

  12. daveau
    Posted August 31, 2011 at 6:48 am | Permalink

    Do I have to say it? What’s that in the middle?

    • still learning
      Posted August 31, 2011 at 7:58 am | Permalink

      Looks like an erect penis, right?

      • daveau
        Posted August 31, 2011 at 8:14 am | Permalink

        That’s what all Rorschach tests look like to me. Or a vagina. Or a desolate global landscape caused by a combination of giant atomic cockroaches who look like my father and glowing golden nuns. What?

        • Dominic
          Posted September 1, 2011 at 1:21 am | Permalink

          The men in white coats will be with you soon!

  13. Flo M
    Posted August 31, 2011 at 7:15 am | Permalink

    Simply put: These moths look like shit!

  14. Nicolas Perrault
    Posted August 31, 2011 at 7:15 am | Permalink

    Mimicry of a carnivorous flowering plant? Might this repel insects and birds?

  15. Posted August 31, 2011 at 7:36 am | Permalink

    To my eye, these look more like beetles (potentially stinky beetles) than flies. Maybe nasty or predatory beetles. With shiny carapaces (see the light-colored “reflection” at what would be the highest spot on the carapaces).

    A bird would eat flies. Might not eat stinky, toxic, gas-expelling beetles. Anybody who has picked up a wide variety of beetles knows how well defended many of them are.

    Don’t forget Huxley’s line……

    • still learning
      Posted August 31, 2011 at 7:59 am | Permalink

      Beetle was my first thought too.

      • Maarcus Stensmyr
        Posted August 31, 2011 at 8:01 am | Permalink

        not that many beetles with bright red eyes…

        • MadScientist
          Posted August 31, 2011 at 4:16 pm | Permalink

          Sure, but do the potential predators perceive color that way?

        • Posted August 31, 2011 at 7:56 pm | Permalink

          That red would be the whole head. I think many beetles have red heads. Typical warning color for toxic bugs.

          • Jon Hendry
            Posted August 31, 2011 at 10:53 pm | Permalink

            Does anything have red mandibles?

  16. Dr. I. Needtob Athe
    Posted August 31, 2011 at 8:33 am | Permalink

    This pervasive use of “meant”, enclosed in quotation marks, demonstrates how our language cripples our ability to express rational concepts because it was developed by our ancestors during a time when they were immersed in religious influence.

    How can we better express this concept that is inadequately represented by “meant”? What’s a better word?

    • Posted August 31, 2011 at 12:47 pm | Permalink

      Yes, this kind of teleological language creeps into a lot of descriptions of evolution, even from those well-known biologists who might be more careful…

      Trouble is, avoiding it is more verbose.

      For “what is it meant to look like” read “what do the moth’s potential predators think it looks like”.


      • ChasCPeterson
        Posted September 1, 2011 at 3:27 pm | Permalink

        “what do the moth’s potential predators think it looks like”

        But even this assumes facts not in evidence. We do not know that the patterns are meant for intended for evolved due to visual predators.

        It’s a plausible hypothesis, but utterly untested.

        • Posted September 1, 2011 at 4:10 pm | Permalink

          Ah! That’s so.

          But then the title of this post is only hypothetical! I guess Matt gave himself some wriggle room with that “?”. 😀


  17. Roberto Aguirre Maturana
    Posted August 31, 2011 at 8:51 am | Permalink

    I think it’s quite obvious (not):

    Anybody who has tried to catch a fly knows that since they are so fast, you should not aim to the fly itself, but to its future location, and predators are probably adapted to do the same. In this case, if a predator aims to the future location of the fly, there’s a big chance that his mouth/beak will land right on the middle of a stinky bird dung.

  18. Posted August 31, 2011 at 10:53 am | Permalink

    Knowing what kind of predators are around would probably help tremendously. It seems odd for a tasty insect to mimic a tasty insect, but we’re thinking in terms of a resemblance to houseflies. As James C, Trager said, these could resemble parasitic flies, or as Lou Jost said, beetles with nasty defenses.

    The main predator of such moths might not be birds, but perhaps mantids or reptiles. My understanding is that mantids hunt by movement, so these don’t seem likely, not to mention that the smell wouldn’t have much effect. Would the geckos or anoles in the area avoid bird shit and/or the flies that eat it?

    Also, what are the chances that this species seeks bird shit itself, and this is a sexual display? Try not to think of this tonight when getting frisky with the significant other…

    The detail is fantastic, though – I love the “reflections” which are almost perfectly situated, but the legs are still being refined.

    • Posted August 31, 2011 at 10:55 am | Permalink

      Actually, I just realized: this isn’t a moth, but a parasitic fly that feeds on entomologists…

  19. Joanna
    Posted August 31, 2011 at 11:45 am | Permalink

    Lol! Don’t wanna get eaten? Make yourself look like poo =D

    Seriously though, this is kind of incredible.

  20. Pablo M. H.
    Posted August 31, 2011 at 2:23 pm | Permalink

    I think this is a total coincidence and another example of our own pattern-seeking tendencies.

    Let’s remember that what may look like flies to us can represent a completely different pattern to the potential predators of this moth. The sensitivity to the electromagnetic spectrum and the structure of the eye is so different between us and most other species that we can only make a poor guess as to what they actually see. Some of them can “see” UV and polarized light, or miss huge portions of our visible spectrum. Not to mention subtleties like depth perception and binocular vision.

    So there’s probably no purpose, no reason, no rationale. Just another eye-catching accident of nature.

    • Posted August 31, 2011 at 8:08 pm | Permalink

      Birds are almost certainly the main diurnal predators of these moths. In my experience, if you stick a moth out on a trunk in the tropics, either it will live until nightfall or get eaten by a bird.

      Whatever the diurnal predators of resting moths, I would think they have vision not terribly different from ours, because most moths look very cryptic to us. To our eyes, their shades of green and brown exactly match the greens and browns of leaves and trunks. These aren’t accidents of nature.

  21. MadScientist
    Posted August 31, 2011 at 4:12 pm | Permalink

    I think I would have to have a lobotomy before I could imagine seeing flies. People are trying too hard to imagine seeing something which simply isn’t there. It is not essential that there be some evolutionary advantage to that pattern.

    What I see is a phallus with the scrotum torn off in two separate pieces – it’s obviously a warning to any predators, especially the apes.

    • Sigmund
      Posted September 1, 2011 at 5:10 am | Permalink

      “What I see is a phallus”
      Wait a second…
      There’s few things scarier than getting your penis caught in your flies!

    • ChasCPeterson
      Posted September 1, 2011 at 3:36 pm | Permalink

      It is not essential that there be some evolutionary advantage to that pattern.

      The pattern gets exposed to the agents of natural selection in every single generation, and we can surmise that its presence is either advantageous (relative to recently-mutated alternatives) or near-neutral with regard to fitness and therefore ‘invisible’ to selection. In the latter case there would be nothing maintaining the pattern, and mutation ought to be able to disrupt it without check.

      I think we can conclude that there almost cetrtainbly is an evolutionary advantage to the pattern.

  22. Tristan
    Posted August 31, 2011 at 9:22 pm | Permalink

    I don’t think that splotch in the middle looks like bird dung. To me it looks like what happens to a moth after death and a few days of putrefaction. The back end, being softer, tends to liquefy first.

  23. PB
    Posted September 1, 2011 at 1:21 am | Permalink

    Reading all of these supposedly scientists’ comments, I am totally at lost. (Indeed it must be a PhD material).

    And I wonder what if all these pesky scientific explanations are all go away (I mean not just me, but from all people, so that I do not look dumb all by myself!), just like in the golden age of the past?

    Yeah, I would just shrugged and say ” God moves in mysterious ways, if indeed he ever moves” – and feel the warm glowing arrogance inside my chest – which I am sure is the spirit of the lord loving me more than a birdshit-looking-lowlies …..

    • theusernamejoewastaken
      Posted September 1, 2011 at 8:56 pm | Permalink

      I didn’t parse this sentence:

      “And I wonder what if all these pesky scientific explanations are all go away (I mean not just me, but from all people, so that I do not look dumb all by myself!), just like in the golden age of the past?”

      And I did manage to parse this one, but didn’t gather your point:

      “Yeah, I would just shrugged and say ” God moves in mysterious ways, if indeed he ever moves” – and feel the warm glowing arrogance inside my chest – which I am sure is the spirit of the lord loving me more than a birdshit-looking-lowlies …..”


  24. MWalton
    Posted September 1, 2011 at 5:01 am | Permalink

    Actually, the central section looks to me like a large wasp with its head toward the head of the moth and its wings folded back along its body. The thorax can easily be seen between the wings. The large blob behind it doesn’t add to the image at all.

  25. Posted September 1, 2011 at 6:57 am | Permalink

    I must have a much more interesting personal life than most of you.
    I immediately saw a phallus celebrating victory right after a boxing match.
    It takes considerable effort for me to see it any other way.
    Of course, I’ve been lonely the past few days…

  26. John Weiss
    Posted September 1, 2011 at 8:44 pm | Permalink

    Who knows what insects see?

    To me, a mammal, it indeed looks like a couple of flies heading for some shit.

    My wife, also a mammal, thought so as well.

    I wonder what the odor was like? Did it smell like ordure? If it did that would clinch it for me: attract flies, let the predators eat the real flies.

    But of course these sorts of matters are – ehem! – complicated.

    Also: I’m not an atheist. I see all the wonders and horrors of life-as-we-know it as literally the gods. If one is talking about an infinite being then one’s talking about our universe. Everything.

    Not the work of the gods, mind you. The gods.

    And yes I believe that they’re crazy/creative.

    • Posted September 2, 2011 at 6:30 am | Permalink

      But the main diurnal predators of adult moths are almost surely not insects, so it doesn’t really matter how insects see. This pattern is painted by the predators, through natural selection.

  27. Posted September 2, 2011 at 12:17 am | Permalink

    Suppose it does look like flies approaching dung. Suppose it does attract other flies. Would it not be simples to assume that the moth or its larvae feed on flies?

    Or, anyway, that the moth or its larvae feed on whatever it attracts. Just because we humans do not like the smell or flies or bugs is no good reason to jump to the conclusion that the moth is adapted to repell something like bird predators.

    • Posted September 2, 2011 at 6:32 am | Permalink

      But moths don’t eat flies.

      • joe
        Posted September 2, 2011 at 8:44 am | Permalink

        Plants don’t eat flies either. would you let that prejudice guide you?

        • Posted September 2, 2011 at 11:35 am | Permalink

          Most plants don’t eat live flies, but if you showed us a picture of a carnivorous plant and you said it ate insects, any biologist would immediately be inclined to believe you even if he or she had never heard of a carnivorous plant before. The adaptations for insect-eating are obvious, and it looks very different from a regular plant.

          But Joe, no moth we know of eats live flies, and they hardly seem equipped for the task, and this moth is structurally just like all the moths that we KNOW don’t eat flies. Of course there are plenty of surprises in nature, but there are also some regularities. This moth has nothing unusual about it except its colors—it has little tiny legs that are not modified to catch flies, and though I don’t know for sure, I will bet $1000 its proboscis is also perfectly normal, not made for piercing flies. Also the flight dynamics of this moth can be guessed by its wing form and its wing surface area to body-mass ratio. This is clearly a slow, fluttery moth, not a fast-flying, highly maneuverable moth like a sphinx moth. It would have a tough time catching a fly.

          • Posted September 3, 2011 at 4:04 am | Permalink

            You’re right, we won’t solve that riddle from out of our armchairs. But attracting something is clearly the alternative to repelling something. Is the picture above a female? If so, what do the males look like? Do they look like the blotches on the wings? Are they attracted by poop smell? Those questions would all have to be added to the list of any Ph.D. having a go at this riddle.

          • Posted September 3, 2011 at 7:18 am | Permalink

            In this group of moths, I think the males and females are not very different. It is good to be open to alternatives, I agree strongly with you on that. But I guess my point is that lots of alternatives can be discarded by careful observation and some evolutionary thinking.

  28. Posted August 5, 2013 at 6:27 pm | Permalink

    There are hundreds of chemical compounds/scents emitted by a decomposing human (or other species) corpse. Not every odor attracts a fly and not every species is attracted/repelled by such odors. If we go with the hypothesis that this is an adaptive mechanism that results in fooling potential predators, such predators could:

    A) smell it and think it’s rotten,
    B) see it is something which is attractive to flies and therefore not of food-value

    Eyespots are normally on the outer portions of wings and serve to distract predators from the main dish (their body) and instead result in getting nibbled on the wing tips which can result in higher survival rates for the butterfly.

    I personally don’t see flies and I have to *really* look to “see” flies. I see beetles more immediately, as others have mentioned. Just going by general size and shape. And just because you can’t think of a beetle species with a red head just remember…400,000 species of beetles.

    All too often we entomologists (and my fellow wannabees) want really-super-duper-hard to find something and then we eventually see it. I’m not saying that’s what this is; but confirmation bias is something we all need to be wary of. Does it look like a type of mimicry? Yeah, sure. Especially with the odor association. But as all of my fellow graduate students like to say when we end our presentations: More research is required.

  29. Maureen
    Posted August 9, 2013 at 11:26 am | Permalink

    This is fascinating! From the untrained eye, from a distance, I see the perfect face of an animal very different than this Moth. Each wing represents an eye (beetle eyes at that) the body is the nose connecting down to the mouth.
    The iridescent centers in the body if the beetles just may glow at night!

2 Trackbacks/Pingbacks

  1. […] bit skeptic, and I’m not even the first one, to feel that way. Matthew Cobb wrote a post at Jerry Coyne’s WEIT addressing the most important problem with the theory: ok, flies makes the whole “bird […]

  2. […] old one regarding possible mimicry in a moth species found in Malaysia and Borneo.  According to the post, some entomologists look at this and see….well, you look first, think about what you see and […]

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