I can't believe how much they eat.  These very small caterpillars are eating large holes in the thistles leaves.  There's no doubt that they love their thistles.  At the moment, we are putting in fresh leaves about 3 times a day.  They may have cleared my garden of thistles by the time they form chrysalis.

It's great to watch as we put in a new batch of leaves.  There's always a flurry of activity as soon as the new leaves go in.  It's almost like they start racing around to see where is the best food.  

I'm surprised at how quickly they can move when they are exploring.  A little caterpillar starts at the bottom of one of the branches and very quickly gets to the end.  Then they grope around trying to figure out where to go next.  Often it seems like they are only hanging on by their toes and reaching out into mid-air.  Makes me wonder how well they can see.  They don't seem to realize that there is nothing out there!

They spend lots of time climbing around.  Sometimes they climb up the sticks, other times they climb up the walls.  Of course, some times they fall down too!  We've tried to make sure there leaves or moss to cushion their landings. 

After watching them for a while, we noticed one caterpillar is a different color.  In the photo, it's the caterpillar on the bottom.   The two above it, are the normal color.  The light colored one seems perfectly healthy, eats a great deal and climbs around just like the others.

At first I thought it had just molted and it's skin would soon darken up.  But after a while, we realized that it was just a lighter color.  My son has decided it's an albino caterpillar.  We'll try to keep track of it as it forms a chrysalis and see what emerges.