Though I have had many butterfly cats before in the garden, I've never seen this stage before. It appears that this caterpillar moved along the frond of the fennel until it was able to cross onto the rose bush.
Two days before I took this picture, I had found him on the rose stem in a "C"- shape, totally still, stiff and frozen. The next day when I went to check, I found it enshrouded in this skin. It apparently takes 10- 14 days inside this cocoon for the transformation to butterfly to complete.
I'll keep you posted on the birth of the butterfly. I hope I catch it.
The caterpillar stage takes several days. They molt 4 times prior to the chrysalis stage and start out looking like very tiny bugs with lots of legs. This is a late stage caterpillar munching the heck out of my bronze fennel.
The caterpillar has now secured itself onto it's molting place with a very fine silk thread. I found this guy yesterday on the stem of an echinacea. When I checked in today he had attached himself and gone all rigid. I'm still trying to figure out how he got there. The fennel he had been feeding on is at least 4 feet away.