Hi...I've been on the computer for a couple of hours searching for the name of the critter that is eating my three lilac bushes and have killed off several of their branches. I saw a picture that looks like it, the cimbex sawfly. However, I could not find where the cimbes sawfly will eat the bark of bushes. They are about an inch long and have bright yellow with black on their thorax.

You can clearly see where these guys strip the bark. They gather and seem to socialize...then munch away. I'd like to know if they are depositing larve...and how I can get rid of them when I don't know where their home is.

Anyone have a suggestion?