Subject: Black Swallowtail cats – 3 different instars
Location: Naperville, IL
June 28, 2012 12:20 am
Hi Daniel~
My daughter found 5 Black Swallowtail caterpillars (Papilio polyxenes) this morning on some potted curly-leaf parsley. I do believe there are three of the five instars represented: 2nd, 3rd, and 4th, judging by their sizes (approx. 1/4”, 1/2”, 3/4”)and by the photos from bugguide of the various instars. They appear to change dramatically from one stage to the next, unlike my Monarchs, which vary mostly by size. I can’t find much info on the duration of the swallowtail life cycle. In the heat we’re having, my Monarch go from new pupa to butterfly in under a week. All the best to you.
Signature: -Dori Eldridge

Black Swallowtail Caterpillars

Hi Dori,
Thanks to your excellent documentation, our readers can see how the Black Swallowtail Caterpillars transform and change appearance as they grow.

Black Swallowtail Caterpillar, final instar

Your photos are so wonderful we are posting them all.

Black Swallowtail Caterpillar


Location: Illinois

3 Responses to Black Swallowtail Caterpillars

  1. says:

    Hi Daniel! Thank you for your kind words. Just one thing: the middle photo caption reads “final instar”. This can’t be correct because the caterpillars have molted at least once more since that stage. They’re now (for comparison) about the size of a 5th instar Monarch. They’re striped with lime green, white and black with orange spots, and they longer have those spiky tufts. I know nothing about the Black Swallowtail life cycle, but my guess is they’re readying to pupate. All the best, and Happy Fourth to you! -Dori

  2. says:

    As fascinating as parasitoids might be, I am happy to state that I have yet to experience them firsthand, other than on tobacco hornworms. The mesh screens on my Monarch (and now Swallowtail) boxes is too fine to allow flies and wasps in, and although I have had more cases of Monarch caterpillar death-by-NPV this year, I have never had the pleasure of witnessing fly or wasp pupae emerge from a butterfly chrysalis. By the way, I saw a Black Swallowtail buzzing my potted curly parsley this morning, and after she left, I found four eggs thereupon. This will be my very first experience with Swallowtail hatchlings. They do seem to take things far more slowly than the Monarchs.

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