Help for a Giant Swallowtail

giant swallowtail butterfly feeding on phlox

A giant swallowtail butterfly (Papilio cresphontes, family Papilionidae) feeds on some pink phlox flowers.

Well, I bid everyone adieu for the weekend, but I have a bit of a quandry on my hands so I thought I’d pop back in, the sooner the better, and look for a little advice from any bug-knowing folks out there.

What we have here is a giant swallowtail butterfly (from 2013). The first one I had ever seen. Fortunately, I saw another one this year! It came around a handful of times into the backyard. Even better? I found some giant swallowtail caterpillars, a.k.a. orange dogs, on a house plant on the back deck!

So what’s my question? My question was going to be what to do if they pupate on the orange tree, which needs to come inside soon as the temperatures continue to drop? But the bigger of the two has disappeared, so now I’m wondering, does anyone know the pupation habits of a giant swallowtail? I’d really like to photograph the chrysalis!

I guess the original question does still hold if the smaller (but still growing) second caterpillar remains on the plant. I’m kind of hoping it wanders off too, but hopefully somewhere in sight. I’m a little worried though; not the best shelter unless under the deck a bit, even the snow can really pile up.

Anyway, basically I’m looking for any knowledge about their pupation. I found one thing on a University of FL page that said they may stay on the host plant or wander a short distance, but that’s been about as specific as I could find. Thanks in advance!

(P.s. a little out of my element without my reverse lens. This shot was taken with a 35mm f/1.8 G Nikkor lens and has been cropped a good amount. Also photos (and video?!) of the caterpillars will be coming eventually, but not until I delete some files so I can upload. The old hard drive is stuffed!)


8 thoughts on “Help for a Giant Swallowtail

  1. I believe the fully-grown larva leave the foodplant to pupate low down on nearby woody stem up to 10 metres from the food plant. The pupa is attached upright to a plant stem by a silk girdle and the cremaster, and overwinters in that position. So the larva needs to be fully grown and needs to pupate outside or at least somewhere constantly cool. Otherwise a sudden rise in temperature will trigger it to hatch. Hope this helps?

    1. Yes, thank you Marc, definitely helpful. I was looking for an idea of how far it might go. 10 meters is a bit farther than I’d hoped, but at least I have an idea now! I don’t feel like there’s a lot of good options for it to pupate — the area is wide open yard not too far off — but I’ll give it another look. Hopefully it did not sneak onto any of the other potted plants coming indoors for the winter — we might have a Christmas (or Halloween) miracle!

  2. So we’ve got to wait ALL WINTER??? I was wondering the same thing because I planted fennel to attract the butterflies. We found several green/black caterpillars in the last two weeks or so. I was keeping track of them to show the grand kids, but they keep disappearing. Don’t tell me I’ve got to look in the undergrowth for a 10 meter radius?

    1. Do you get a lot of snow in Oregon, Pat? It sounds like you probably have black swallowtaiils (as opposed to giant swallowtails). This would be an example of a black swallowtail caterpillar:

      Not sure about their range, the Eastern Black Swallowtail is pretty widespread or maybe there is a western variant. The keyword though was “fennel” as that is right in their wheelhouse. They are pretty good at disappearing in my experience.

      1. We don’t get much snow on the coast, none last year, some the year before.
        The parsley caterpillar looks very similar.
        I had to chuckle over your explanation of using your future brother-in-law’s lens. I tried leaving a comment but it wouldn’t let me.

    2. Hmmm, that’s odd you couldn’t post a comment. Not sure what that’s about. And it’s funny what one writes on a blog, I can hardly remember any of it! I did figure out that ghosting X with the cheapie extension tubes, which I will hopefully get to mention this week.

  3. Well it’s up to 10 metres so it could be within 1 metre. I think they’ll always opt for the nearest secure place to pupate. As for overwintering, it depends on the climate. In Florida for example I believe there can be up to 3 broods a year. Alternatively, you can fit the caterpillars with tiny radio trackers, expensive but effective ;0)

    1. I think I read that they fly all year in Florida, possibly on the U of FL page; a much different story in Massachusetts of course. In the end I hope, they just make it out alive. But not much luck in locating the wanderer so far.

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