A few of the caterpillars started hanging in a J shape.  They stopped eating and just hung out for a day or two.  One morning there was a chrysalis hanging from a branch.  I've been trying to get pictures but it doesn't seem to have worked out.  I'll post them when I get a good image.

The chrysalis just sit there most of the time, looking like a dead leaf.  Suddenly, there's a movement inside and the whole thing wiggles.  It's kind of startling.

Only one of the caterpillars decided to form a chrysalis on the sticks we put in the terrarium.  The rest of them have chosen to climb up to the blue roof and make their chrysalis there.

Another interesting thing is the size of the different caterpillars.  We knew there were some little ones, but they are still happily wandering around eating leaves.  I had expected them all to go into chrysalis within a day or so.  But it's been at least 3 days since the first chrysalis and they are still happily munching on thistles.

Read more about raising Painted Lady Butterflies.