Sunday, August 21, 2011

Caterpillar Transformation and a Surprise!

At the end of July my boy found a tiny little caterpillar, that we quickly identified as a Black Swallowtail. We left it to munch in our carrots and when it was full grown we brought it inside so that we could watch it transform.

We put him in an aquarium, and gave him some carrot greens. Black swallowtails also eat fennel, parsley, dill and queen anne's lace.

i placed a few sticks inside our aquarium, so that he could find a perfect place to form his chrysalis. When he found a good spot, he got very still and stayed like that for a quite a while. Then we watched him turn around on the stick, and spin a bit of silk.

He stuck his back feet in the silk, and spun a thin silk sling to support his body. Then he got into position. He stayed like this for maybe 24 hours or so. We started to notice he seemed to be puffing up a bit, and his skin began to look very stretched.

The more he puffed the thinner his skin became and it changed to a dull color. He let go of the stick, and his skin began to split. He slowly wiggled the skin down his body.

Underneath, you can start to make out the familiar chrysalis shape. His skin is about half way down now, and he is still working on pushing the skin off.

One the skin is completely off, he rests. His new chrysalis is green and soft.

After a few hours, his new skin has darkened and hardened into it's chrysalis. It's camouflaged to resemble a dead leaf on the twig, or a part of the branch. After pupating for around 2-3 weeks the Black swallowtail butterfly should emerge from its chrysalis. Caterpillars that are found in the fall, will often overwinter in their chrysalis emerging instead in the spring. Our Caterpillar formed it's chrysalis on August 1st, so we have been patiently waiting for him to make his apprentice.

Instead we got quite the surprise!

Instead of a butterfly, this Ichneuman parasitic wasp emerged from the chrysalis!

When our little caterpillar was outside munching carrots, a female wasp had found it and laid her egg inside the caterpillar. As the caterpillar continued to feed and grow the wasp egg hatched and a tiny wasp maggot began to feed on caterpillar. While our caterpillar was pupating, the wasp larva was feasting.

When the wasp is fully grown, it exits the chrysalis through a large hole in the side. Although it just part of nature, it was rather disappointing being that it was our only Black Swallowtail cat this year. My daughter was completely fascinated by the whole thing, but my boy was a little more bummed. We've witnessed other parasite infections with the monarch caterpillars we've raised.

No matter how many times we raise caterpillars, it is always a learning experience. The process is always amazing, no matter what happens to hatch out.


  1. awwww....bummer deal...the learning is all well and good, but a wasp...pooh!

  2. Eww that is gross! Blech! What a disappointment. Cool thing to learn..but still...

  3. amazing! I would have been very surprised after all that anticipation!

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  5. I'm so phobic about wasps that I find this pretty horrifying. I would never tell my daughter that though... I'd go for ..oooh, interesting nature!
    I had no idea this was even possible. I keep learning htings here.

  6. Woah! Totally awesome! Definitely disapointing, but awesome nonetheless.
    Wasps are so great, and they're very helpful in parasitizing the nasty caterpillars..... but it would be nice if they left the butterflies alone!

  7. That is amazing! I showed my daughter your story and she wanted to hear again and again! Never heard of a story like this! Thanks for sharing! Sorry there was no butterfly!