Monarch Chrysallis

This is on my friends swan plant. She has hundreds of caterpillars' but mine are still getting eaten as they appear. I thought it was wasps but what else could it be. It is most disappointing.
Have spent all night on PSNZ business and it is now 10.45 pm so am giving up and going to bed. A case of peaches to bottle tomorrow  and entries to get ready for focus so will have to be on the ball.