On Monday, after about three days in the “J” position (see this post for images), this Monarch caterpillar straightened out and began to shed its outer skin. In the time it took me to get my camera, the gyrations began and the skin was almost shed. It appears that the skin behind its neck and shoulders split and then the caterpillar wiggled its way out of the skin. It remained attached to the milkweed leaf throughout the process.
The chrysalis (the new skin) is very soft after shedding but within an hour, it hardens to become a protective shell for the caterpillar inside. During the next 9-14 days, this caterpillar will transform into a butterfly. I hope to be able to photograph the progression. The leaf this caterpillar is attached to, it starting to yellow. I hope it remains attached until this Monarch emerges. Question is, should I put a protective wrap around the entire plant to protect it from predators?
I found this nice detailed photograph that illustrates the pupa transformation.