Moth mimics bird poop

Okay, is everyone ready for footie? Yes, I thought so. But we still have nearly an hour, so let’s have a bit of biology.

We all love mimicry, and if you’re a regular here you’ve seen all kinds of it, including many animals (insects, frogs, spiders, and so on) that look like bird droppings. Those droppings are, of course ubiquitous. (Did your car get dumped on this week? Mine did). But if you evolve to resemble them, predators will leave you alone.

This is from Animal Odditiesand although it doesn’t demonstrate any new principles of evolution, it’s another cool example of how natural selection molds animals to hide their true nature. But here, let the website talk:

Mother Nature is pretty awesome, especially when she has the sense of humor of a ten year old boy.

You might be aware that the caterpillars of the giant swallowtail butterfly have evolved to look like bird droppings as way to avoid being eaten by predators. Most predators don’t enjoy eating bird poop, so this strategy ensures that many giant swallowtail caterpillars will survive long enough to pupate and emerge as winged adults, which will in turn mate and lay eggs and keep the species going.

Well, giant swallowtails aren’t alone in using this strategy. My National Wildlife Federation colleague Dani Tinker took some pics of an awesome moth in Great Falls, Virginia last weekend that also looks just like a pile of fresh bird poop.

Meet the pearly wood nymph  [Eudryas unio]:


Pearly wood nymphs are found across eastern North America and lay their eggs on wild grapes, hibiscus, and evening primrose, so if you plant these in your garden, you might just be able to attract this cool moth to you own backyard.


Now we’re not sure that this evolved to mimic bird shit, but it sure looks like it, and the resting pose, with the forelegs extended out, also creates that illusion. You can see a lot more pictures of the species at BugGuide. 

Just to show you what you or a bird might see, here’s a related species, the Beautiful Wood Nymph (Eudryas grata) from Observe Your Preserve. Notice that all these moths rest quite visibly on the surface of leaves, which I suspect is also an evolved behavior to enhance the mimicry:


Photo by Carl Strang

Come to think of it, someone should write an article for Audubon or Natural History about animals that mimic excrement. Don’t you think people would read it?

h/t:  National Wildlife tw**t via Matthew Cobb


  1. GBJames
    Posted July 8, 2014 at 12:24 pm | Permalink

    Another crappy disguise.

    • Diana MacPherson
      Posted July 8, 2014 at 2:11 pm | Permalink


  2. Mark Sturtevant
    Posted July 8, 2014 at 12:37 pm | Permalink

    For some inscrutable reason, my passion for insects includes a very warm, gooey place in my heart for the various bird poop mimics. I know this species of moth, and it is a fav.
    A life goal of mine is to find giant swallowtail caterpillars. I see the adults (always in a hurry going somewhere, very hard to catch) but I have ever been able to find their larvae.

    • Posted July 8, 2014 at 4:20 pm | Permalink

      Citrus. Even a dwarf lemon in a pot.

      • Posted July 8, 2014 at 9:24 pm | Permalink

        I know. But not many of those in Michigan. My best bet is prickly ash, but I have not seem ’em.

  3. eric
    Posted July 8, 2014 at 12:39 pm | Permalink

    someone should write an article for Audubon or Natural History about animals that mimic excrement.

    So, basically, you’re asking those magazines to pick up your articles on Deepak Chopra?


    • Posted July 8, 2014 at 12:50 pm | Permalink

      It really is a fascinating topic. Some mimic fresh poop, others mimic dry poop, and others mimic little flecks and smears of bird poop. Aliens could learn all about bird poop by just looking at its mimics.
      Although most poop mimics resemble bird poop, there is a small beetle that mimics caterpillar poop. Looks just like it.
      Really, this is fascinating.

      • Posted July 8, 2014 at 1:42 pm | Permalink

        So much poop, so little time…but I suppose aliens reaching our planet know a little bit about time-management.

  4. Hempenstein
    Posted July 8, 2014 at 12:56 pm | Permalink

    Mostly evolution proceeds incrementally, but occasionally, apparently, excrementally.

    • darrelle
      Posted July 8, 2014 at 1:17 pm | Permalink

      Sometimes effluently too.

  5. Kevin Alexander
    Posted July 8, 2014 at 2:01 pm | Permalink

    Could be some kind of sexual selection. I can imagine a pick up in the moth bar.
    “Dang woman, that’s some fine shit you got going there.”
    “Thanks, your place or mine?”

  6. Diana MacPherson
    Posted July 8, 2014 at 2:12 pm | Permalink

    This mimicry is craptacular!

    • John Scanlon, FCD
      Posted July 8, 2014 at 8:14 pm | Permalink

      The bile-green fringes between poop and urate are the icing on the cake, as it were.

  7. Posted July 8, 2014 at 4:06 pm | Permalink

    So in at least a couple of senses for this moth, proximity to stalking predators does not necessitate evacuation.

    • John Scanlon, FCD
      Posted July 8, 2014 at 8:16 pm | Permalink

      I wonder if there are any animals that mimic the poop of poop-mimicking animals?
      …and so ad infinitum.

  8. Diane G.
    Posted July 8, 2014 at 11:30 pm | Permalink

    And completely unrelated…I free associated from moths & excrement to the story of the moth that lives on sloths and eats their excrement, which resulted in one of the better scientific paper titles” A Coprophagous Moth on a Three-toed Sloth.

    • Diane G.
      Posted July 8, 2014 at 11:31 pm | Permalink

      ” = :

  9. Duncan
    Posted July 9, 2014 at 12:27 am | Permalink

    The article should be called ‘Stuff that looks like shit’.

    I’d read it.

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