Complex interactions between caterpillars, ants, and butterflies

I don’t know the species of either the butterfly or the ant in this video taken in Peru, but the interactions are complex.

One level is probable mutualism between the ants and the caterpillars. Although the authors don’t mention this for these species, there are a lot of caterpillar species that are guarded and protected by ant species. In these cases, the caterpillar, after nomming vegetation, secretes a sugary exudate that the ants feed on, and in return the ants keep the caterpillar safe from some predators. I suspect that’s what’s going on here; see the second video for such a case.

As for the adult butterfly “parasitizing” the ants, I’m not sure that’s what’s going on—unless the ants inadvertently signal to the adult butterflies that there’s nectar at the tip of the bamboo. Otherwise, it’s just competition for food. One puzzle is why the ants allow the butterfly to feed near them without driving them away.

While the butterfly wing patterns may mimic the ants, if that’s the case it may not be to fool the ants into accepting them (ants have lousy vision), but to fool predators who are wary of stinging  ants. However, the mimicry is not that great. Another possibility is that the ants accept the adult butterflies because they’re going to lay eggs that produce the caterpillars that in turn exude that delicious nectar. And that would be a convoluted form of mutualism. It’s all very complicated, and I haven’t seen any papers on what’s shown in the video.

The notes from the YouTube video:

A walk through the woods in the Tambopata Amazon Rainforest can turn into a discovery of a never-before-seen behavior! Aaron Pomerantz (@nextgenscientist) and I (@phil_torres) collaborated on project to solve the mystery behind this incredible butterfly.

Here’s a short video on an ant/caterpillar mutualism, which also involves the evolution of auditory signals in the caterpillar. Remember, evolution is cleverer than you are.

h/t: Barry


  1. rickflick
    Posted June 16, 2016 at 2:28 pm | Permalink

    Fascinating stuff. I didn’t know ants and Lepidoptera got along like this.
    It’s a bit disturbing to hear the narrator imitating the overly amused voice of the kindergarten teacher. I guess that’s also a form of symbiosis. I think it’s supposed to facilitate learning as in sugar to your ears.

    • Paul S
      Posted June 16, 2016 at 2:56 pm | Permalink

      Yes, polar opposite between the video narration and PCCEs narrative. Cool, none the less.

    • Jonathan Wallace
      Posted June 16, 2016 at 5:26 pm | Permalink

      As it happens ant-butterfly interactions are quite common, especially in the Lycaeindae (I don’t now what family the butterfly in the clip belong to but it doesn’t look especially like a lycaenid).

  2. Mark Sturtevant
    Posted June 16, 2016 at 3:15 pm | Permalink

    That is pretty neat. The butterfly might smell like its caterpillar, and this keeps it from being shooed away by the ants.
    As for the color pattern.. well maybe it looks like ants to the ants (or to predators). Like the smell idea, this too is testable.

    • loren russell
      Posted June 16, 2016 at 3:28 pm | Permalink

      I’d agree that the adult butterfly may carry over scent cues from the larva. Would be interesting to know if the scent is nest-mimicking [identical with the host ants] or specific to the caterpillar/butterfly — the latter implying the ants recognize the lep as a desirable resource, not just a nest mate.

      It’s stated that a number of ant species protect/tolerate this lep. If so, presumably NOT nestmate-mimicking.

      I’d buy that the visual mimicry is aimed at the ants — just blurry red circles, and it’s not evident what visual predator would miss the butterfly-outline or approach from the underside..

      So much to learn, so little time.

    • Posted June 16, 2016 at 5:20 pm | Permalink

      Yes, that sounds reasonable.

      • loren russell
        Posted June 17, 2016 at 12:00 am | Permalink

        A further thought — if several species of ant do care for these larvae [and at least tolerate the adult butterflies], it starts to sound like the reef cleaner guilds -in which a wide range of species appear to “play fair” for mutual benefit.

  3. Mark R.
    Posted June 16, 2016 at 3:26 pm | Permalink

    Really cool videos. Evolution’s wonders never cease to amaze.

  4. W.Benson
    Posted June 16, 2016 at 10:44 pm | Permalink

    It bothers me that the narrations of the two videos are so amateurish and give such distorted accounts of the natural history they depict.
    The role of sugar glands (extrafloral nectaries) in attracting many kinds of ants that defend plants from herbivores was well established by experiments in the 1970s. Much work exists on the sugar secretion by tropical caterpillars, in particular those of the family Riodinidae, and the role the ants play in driving off parasitoids and predaceous insects. The existence of vibratory hairs in riodinid caterpillars has been known since the 1960s and their function to attractive protective ants was shown experimentally by P.J. DeVries in 1990. Wikipedia has post called “singing caterpillars” and DeVries treats them in the first chapter of vol. 2 (Riodinidae) of his 1997 work The Butterflies of Costa Rica.
    As to the `never-before-seen-behavior` of Pomerantz and Torres of butterflies sharing plant nectar with ants, DeVries reported a similar case almost 20 years ago in Butterflies of Costa Rica. A local Adelotypa species (A. senta) was observed “by D. Murray, who noted that males of A. senta feed on the extrafloral nectaries of their host plant for extended periods of time (up to 24 hours), and that during this time, the ants frequently antennate the forlegs of the adult butterfly. These observations,” says DeVries,”suggest a very close association between the butterfly population and its hostplant and may indicate ant-mediated oviposition in the females.”
    Also, the bullet ant (Ectatomma tuberculatum?) shown with the butterfly does not really sting that badly. If you want a really knock-you-on-your-butt sting, try picking up a tucandeira ant, Paraponera clavata.

  5. Dominic
    Posted June 17, 2016 at 5:15 am | Permalink

    There is a European butterfly, Maculinea arion, the large Blue, that also has a complex relationship with ants AND a parasitic wasp. david Attenborough wrote/spoke about the fascinating story in a radio seris/book…
    Read a brief summary here –

    • Dominic
      Posted June 17, 2016 at 5:20 am | Permalink

      In this case however the caterpillar eats the ants so is a predator, rather than being some form of mutualism…
      Maybe the ants don’t drive the adult butterfly away is as they smell like ants? ants may have poor vision but they have good sense of smell I understand…?

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