Saddleback Caterpillar

Saddleback Caterpillar July 31

The saddleback caterpillar is one of North America’s stinging caterpillars. Each hollow spine is equipped with venom, and bright patterns on its back advertise the danger. Everything about it signals “Don’t touch!”

I found my first saddleback caterpillar in the yard yesterday, and I hope there aren’t many more. I’m not interested in finding out exactly how painful their stings can be.

Saddleback Caterpillar July 31

The University of Florida’s online reference says this: “The saddleback caterpillar is encountered most frequently as a medically significant pest, and has minor effects in landscaping and agriculture.” So, while my caterpillar was doing a very neat job of eating one of the iris leaves, its primary impact in the yard is being a “medically significant pest.” (Something about that phrase makes me want to write a poem.)

Saddleback Caterpillar July 31

The only North American caterpillar with a more venomous sting than the saddleback is the puss caterpillar, which I encountered in the yard a few years ago. Here’s a video I made at the time:


When I found the puss caterpillar in 2010, our newspaper’s wildlife columnist published one of my photos. She later published an article spotlighting readers’ stories of having been stung by both kinds of venomous caterpillars: Those cute little caterpillars can pack a big, painful wallop.

Yet another very good reason to wear gloves while working in the flower beds…

Saddleback Caterpillar July 31


7 thoughts on “Saddleback Caterpillar

  1. Sharon Poch August 2, 2014 / 10:03 PM

    I used to think caterpillars were so cute–from now on, will give a wide berth. What type of winged creatures do they become?

    • Rae Spencer August 6, 2014 / 3:07 PM

      Saddleback caterpillars become a rather plain brown moth. (See images here.) The furry puss caterpillars grow into equally furry moths called flannel moths. (See images here.) I’ve had no luck finding flannel moths in the yard, but I’ve definitely seen saddleback caterpillar moths. (Even so, when I looked through my moth archive, I couldn’t find any photos… 😦 )

  2. jeanryan1 August 1, 2014 / 3:25 PM

    You sure have an equal opportunity backyard, indicating a healthy ecosystem. Must be your gentle approach.

    • Rae Spencer August 1, 2014 / 3:42 PM

      I have to admit that I paused for a few minutes, after taking these photos, caught between fear of the caterpillar’s potential sting and my general inclination to live-and-let-live. In the end, I decided to leave it alone. (So it fared better than our black widow spiders, which I am still trying to eradicate…)

  3. Book Nanny August 1, 2014 / 2:33 PM

    My goodness, Rae, what strange creatures! I don’t think we have anything like that this side of the Atlantic.The saddleback is beautiful in its own way, but the puss caterpillar looks pretty scary and horrible! How big is it? It seems to be a fair size from the video.

    • Rae Spencer August 1, 2014 / 3:48 PM

      The saddleback caterpillar was maybe three-quarters of an inch long, so it wasn’t very imposing. The puss caterpillar wasn’t much bigger, maybe a bit over an inch, but it looked bigger because it had so much hair! 🙂

      • Book Nanny August 2, 2014 / 9:07 AM

        Thanks, Rae, it sounds like a bug to avoid! 🙂

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