Help! Help! Help!!!! My Garden

What is killing my Monarch grubs.  Back awhile before Christmas I had lots of big healthy grubs and all of a sudden they were gone. Diagnosis please
I now have about 20 plus more and today discovered this little black beast near two of them. Is it my killer and what is it. Cant spray as would kill the grubs. Another one in extras.
Rain stopped this afternoon and even had some sunshine. More beautiful meals delivered, I have been so spoilt, hard to believe