When it's time to change, the caterpillar finds a surface to hang from and spins a silk pad, from which it hangs, head-down, in a J shape.
The first sign that he's getting ready to shed is that the antennae wither.
After some squirming, he eventually relaxes down from the "J".
As the skin pulls away from what's beneath, the colors dull quite a bit. There's a clear line where the skin will split between the antennae.
All images herein are Copyright 2004, by Roy Johnson. Please do not use them without express permission.