Subject: What kind of caterpiller is this?
Location: Clearfield County PA
September 4, 2012 10:10 am
We were recently at a family get together in PA (near the DuBois area) and we found this caterpiller crawling on te picnic table. My son wanted to keep it and look it up when we got home to see what kind it was. (A few years ago we had found what turned out to be a polyphemus moth when it was a caterpiller & it spun it’s home over night so we found out how to care for it until it emerged the following spring. Quite a nice way to learn & observe 1st hand.). Have you any idea what this caterpiller will turn out to be since it has also spun it’s home already?
Signature: Curious in Ohio

Black Swallowtail Caterpillar

Dear Curious in Ohio,
This is the caterpillar of a Black Swallowtail, a lovely, large butterfly with black wings and numerous spots and markings.  For the record, Black Swallowtails do not spin a cocoon.  The caterpillar will spin a silken girdle to support the chrysalis in an upright position, but the chrysalis is otherwise bare.

Thank you so much.  Can you tell me if there is anythign specific we should do to make sure it is well through the chrysalis stage?  Also – when will it emerge?  Thanks!

Ensure it is not too dry nor too damp.  Give it fresh air.  We suspect it will remain in the chrysalis for several weeks.  We found a wonderful page on Joyful Butterfly that should answer all your questions.

Location: Ohio

2 Responses to Black Swallowtail Caterpillar

  1. says:

    Even though it is still early September, I am not entirely sure that Curious’s PA pupa will eclose in a few weeks. In my experience in Illinois, Eastern Swallowtail caterpillars that pupate in late summer overwinter as such and will not emerge until late May or early June the following year. In that case, I leave my pupae outside in a wooden box with a mesh “door” for fresh air, as you suggest. Even in the harshest winters, full of snow and below-freezing temperatures, healthy adult butterflies emerge in the spring. Despite being tempted to bring the pupae inside during extreme cold snaps, I don’t; the last thing I would want is for a butterfly to emerge in my garage or basement in the middle of winter with no chance of surviving outside. It might be the weather that decides, and the best course might be to check it daily. All the best!

    • bugman says:

      Thanks so much. We were trying to find information on the hibernating stage of the Black Swallowtail. We suspected it to be the chrysalis, but we didn’t want to rule out eggs, though if eggs overwintered, the plants upon which they were laid might not overwinter. We know that parsley overwinters quite well.

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