Question
We have a well established lilac that has attracted very large wasps, after it
finished blooming. They started coming around the plant 1 month ago.  They
are very large, approx 1 1/2' long.  what are they, what are they doing and
how do I get rid of them?  Are they hurting the plant?  We have many plants
in our garden to attract bees and butterflies but these are out of our comfort
zone.  We are located in Southern New Jersey

Answer
Hi there. I to am in South Jersey. There are thousands of insects that fall in your description but here are 3 I have been seeing a lot of:
1: Giant Hornet
2: Humming Bird Moths
3: Cicada Killers
Google these 3 any see if any fit your situation.
Let me know how you make out,Bill