A while ago I posted some photos of a Silver-spotted Tiger Moth caterpillar. Later in the summer I came across another one and decided to keep it and see the moth. (I actually spotted it just as Shelley and I were going out. She waited while I ran back to the house, got a container, and got the caterpillar. It's a good thing she's patient with my eccentricities.) Four weeks later, here's what emerged:
Back to the beginning, here's what the caterpillars look like:
The first challenge was what to keep the caterpillar in. At first, I used a large mason jar. But I realized that wasn't going to work well when the moth emerged. I'd have to get it out of the jar to photograph it, and it would be hard to do that without disturbing the moth. I eventually found a food canister from the dollar store that I could use inverted. That way I could remove the main part of the canister with minimal disturbance. I drilled some holes in the bottom (now top) for air. I also needed something to hold the pine twig with the cocoon and a longer twig for the moth to climb up. Shelley found me a jewelry ring holder that worked perfectly with a rubber band to hold everything together.
The morning after I captured the caterpillar it started to build its cocoon. It started with a faint ghost shell of silk, which it reinforced with its hairs. It worked very slowly so it didn't seem to be doing anything, but every time I checked on it the cocoon was a little more substantial. I'm not sure how it managed to remove its hairs and build them into the cocoon. With its mouth presumably. Here's the mostly completed cocoon.
It was supposed to take 3 to 4 weeks for the moth to emerge. After 4 weeks I was starting to think it was dead. Instead, I should have been watching it more closely. Sadly I missed the emergence. Late in the evening I walked by the kitchen table where I had it, and out of the corner of my eye noticed something different. The moth had emerged from the cocoon and climbed up the twig I'd placed for that purpose. I was afraid it would emerge at night, but late evening makes sense - a little warmer, and lots of darkness ahead. I scurried around gathering camera and lights. It looked like its wings were fully deployed so I was afraid it would be ready to fly. But it sat motionless when I removed the container and throughout the bright lights and photography. And it was still sitting motionless when I left it outside and went to bed. No surprise, it was gone in the morning.
Butterflies just have a chrysalis - a hard shell around the pupa. Moths have a similar shell around the pupa, with a cocoon around it. Moths first have to escape the hard shell, and then the cocoon. Some moths produce a "solvent" that weakens the cocoon so they can push their way out.
It's amazing that all the materials to make the moth were completely repurposed from the caterpillar. No more, no less, no construction debris left over. (Other than the cocoon and the pupa shell.) The moth basically liquefies inside the shell, and that liquid reorganizes itself to build a moth. Amazing. Endless forms most beautiful indeed.
