A remarkable case of mimicry: katydid nymph mimics ant

The nymphs (juvenile stages) of katydids—orthopterans from the family Tettigoniidae—nymphs look pretty much like miniature katydids; here’s a screenshot of what you see when you do a Google image search for “katydid nymph” (click to enlarge):

But one species, at least, has modified its nymph stage to look like a hymenopteran. Here’s a photo by Piotr Naskrecki taken in Mozambique:

Now clearly selection is responsible for this, but what kind? Does it hide from predators by running with real ants (crypsis), or does it resemble a stinging or toxic ant that predators have learned to avoid (Batesian mimicry)? I don’t know, but it’s a lovely mimic.

h/t: Matthew Cobb, who keeps his eye on Twitter

21 Comments

  1. GBJames
    Posted April 28, 2017 at 12:35 pm | Permalink

    I love that bit of katydid green on the belly!

    • W.Benson
      Posted April 28, 2017 at 3:08 pm | Permalink

      The green gives the impression of an ant’s waist. When it is too difficult to converge on the form of the model, the mimic resorts to optical illusion.
      Ain’t adaptive evolution amazing!

  2. Posted April 28, 2017 at 12:36 pm | Permalink

    Wow, that is amazing mimicry. (Even without seeing the ant mimicked.)

  3. busterggi
    Posted April 28, 2017 at 12:51 pm | Permalink

    Crazy cool.

  4. Mark Sturtevant
    Posted April 28, 2017 at 12:53 pm | Permalink

    It could be sufficient to just look like an ant since ants as a rule taste bad. Ants sit out on leaves and flowers, and a thing that looks like an ant will be assumed to be an ant by a predator.

    In light of the recently published idea that insects that mimic wasps may do so to avoid predation by wasps, I think we should be open to the idea here that ant mimics are doing so to not be attacked by ants. There is a flaw to this idea (ants rely on scent to recognize nest mates), but i would not discard it right away.

    • ToddP
      Posted April 28, 2017 at 3:23 pm | Permalink

      That was my initial thought as well, do the real ants themselves pose a danger to the katydid nymphs? If so, then it’s a form of camouflage to go unnoticed, like wearing the uniform of your enemy to blend in.

      • GBJames
        Posted April 28, 2017 at 4:11 pm | Permalink

        Ants are not all that visually oriented. If you want to scam them you need to use pheromones.

        • Posted April 28, 2017 at 6:08 pm | Permalink

          This is true, and a likely weakness to the idea. Of the cases where an insect mimics an ant to avoid detection by ants, they use scent and they live with the ants to exploit them. I don’t know of precedent where they resemble ants.

    • Posted April 29, 2017 at 6:43 pm | Permalink

      I doubt that ants would be very tasty except to vermilingua–all that formic acid–but I have seen birds eat them. I guess all that matters is that they be less tasty than katydids.

  5. Stephen Barnard
    Posted April 28, 2017 at 1:15 pm | Permalink

    That’s astonishing.

  6. Brian Salkas
    Posted April 28, 2017 at 1:49 pm | Permalink

    How do we go about testing this? could it be possible to paint some of them and see who ends up eating the painted ones?

  7. loren russell
    Posted April 28, 2017 at 2:05 pm | Permalink

    Would “running with ants” really be crypsis? It’s not that insectivorous predators don’t see ants on the run, or don’t see them as insects [or ‘noms in the abstract’]. Rather, protection would come from predator avoidance of ants, or a particularly nasty sort of ant. If anything, a katydid in a mass of ants has to be a better Batesian mimic. Rather than cryptic, it has to mimic both form and movement of the surrounding ants. Judging from widespread ant-following among birds, a misfit in the ant forage line is still exposed to predation, and in fact may be exposed to more discerning predation.

    • Posted April 28, 2017 at 2:08 pm | Permalink

      It could be Batesian mimicry if predators have learned to avoid the ants it’s mimicking. If predators go for the ants, it may be crypsis: safety in numbers.

    • nicky
      Posted April 28, 2017 at 3:08 pm | Permalink

      ‘Both the form and movement’ and the pheromones, I’d guess.

      • loren russell
        Posted April 28, 2017 at 3:31 pm | Permalink

        Yes, to survive being picked off by the ants. I was thinking of the [vertebrate] predators here.

  8. Barry Lyons
    Posted April 28, 2017 at 4:24 pm | Permalink

    Once again, this mimicry business is the CRAZIEST thing in evolution. I accept it (because there’s evidence), but I can’t believe it!

    • nicky
      Posted April 29, 2017 at 11:45 am | Permalink

      Oh yes, I can believe it. My point is that pheromones would allow the katydid larva to blend in. Ants live by pheromones, if not blending, the larva would be quickly devoured.
      So it is probably even more sophisticated than what meets the eye.

  9. Nick
    Posted April 28, 2017 at 11:55 pm | Permalink

    That’s really cool

  10. Posted April 29, 2017 at 12:00 am | Permalink

    Echoing, “Wow!” regarding the mimicry.

    – Carl

  11. Posted May 8, 2017 at 7:23 am | Permalink

    It is a very good mimic – even the ‘waist’ of an ant imitated by the light patch… wow!


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