This year, we found one really white caterpillar and a couple with white fur.  Here's a picture showing the white caterpillar and on of the regular painted lady caterpillars.  The differences are very noticeable!

The weather hasn't been great this year and most of our plants are a bit late.  There are lots of thistles for them to eat, but our borage is almost non-existent.  So we've been trying lots of different leaves to see what they will eat.  Of everything we've tried, it turns out they are happy to eat butterfly bush!