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Viceroys — Master Mimics

8-17-18 viceroy metamorphosis

A plump caterpillar is irresistible to many insect-eating birds, and some of them (notably Viceroys and Giant Swallowtails) have outfoxed their predators by assuming the appearance of bird droppings, which one assumes is a far less appealing meal.  They do this using color, pattern, choice of resting place and even position – contorting their bodies to match the shape of bird droppings. The Viceroy (Limenitis archippus) uses this technique during its later larval and pupal stages.

The adult Viceroy butterfly also uses mimicry to enhance its survival, but it mimics another butterfly — the Monarch — not bird droppings.  Both the Viceroy and the Monarch are unpalatable and contribute to each other’s protection from birds with this strategy, a relationship known as Mullerian mimicry.

In New England there can be up to three broods of Viceroys, with the larvae of some of the second brood and all of the third brood overwintering and pupating in the spring.

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9 responses

  1. Bill on the hill

    Good morning Mary… I can’t think of a better way to start my day when your latest post is in my mailbox!
    The bottom image very much looks like a monarch to me as the Viceroy is quite crafty indeed!
    Bill Farr…

    August 17, 2018 at 7:37 am

    • I agree, I thought it was a monarch when I first looked They look to live in the same area. I guess that is why it works as a cross-over deterrent. I have not heard of this butterfly before.

      August 17, 2018 at 9:03 am

  2. Courtney Dobyns

    Hi Mary
    I have some photos of the Giant Swallowtail butterfly caterpillar if you need some.
    They come almost every year to my Dictamnus plant and lay eggs. It is exciting to watch these strange looking creatures develop.
    I would love to share photos.
    As usual, I love your posts!
    Courtney Dobyns

    August 17, 2018 at 8:18 am

    • Hi Courtney,
      I would love to see your photos – you can email them to me at I did have the good fortune to have a giant swallowtail lay eggs on an orange tree I had outside, so got to photograph the larvae — what a thrill! Thank you for thinking of me.

      August 18, 2018 at 8:53 am

  3. Kathryn

    Are there any obvious ways to differentiate a Viceroy from a Monarch? Are Viceroys smaller?

    August 17, 2018 at 10:15 am

    • Hi Kathryn,
      Yes, the easiest differentiation is that Viceroys have a thin, black line across their hind wings which Monarchs lack. They are also smaller, but that can be difficult to assess in the field.

      August 18, 2018 at 8:51 am

  4. Alice Pratt

    Both beautiful butterflies…for as many times as I’ve seen a Monarch landing on milkweed this summer, I was lucky to only see her caterpillar once, late afternnon…gone the next morning…maybe it had gone to make a chrysalis.

    August 17, 2018 at 2:16 pm

  5. Ellen Blanchard

    Here’s a nice link to a butterfly quiz. It will show you the differences between monarchs,
    viceroys and queens. The viceroy has a black almost horizontal line across it’s bottom
    wings. The other butterflies do not have this black line.

    August 18, 2018 at 8:52 am

  6. Thanks for this post, it’s nice to see the Viceroy instar stages.

    August 18, 2018 at 9:25 pm

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