My Yard ~ Red-spotted Purple Caterpillars & Northern Hammertail

I have 2 small potted cherry trees that I brought from NJ.  Each year since I moved here I have seen Red-spotted Purple eggs and caterpillars.  This year they are earlier than previous years.  I check every morning to see how they have grown over the past 24 hrs.  2 of them look like they should be going into a chrysalis soon.  I am hoping they place it somewhere I can see it when they are getting ready to emerge.  There was a robber fly hanging around the tree that worries me that it will snatch the caterpillars and eat them.

Northern Hammertail Robber Fly