Nibbled around the edge

While I was waiting for my brother to pick me up this morning I was noticing all the neatly nibbled lilac leaves. Something has dined carefully around the edges of a lot of the leaves. There is also a sort of mildew on a lot of them too. I hope they come back okay in the spring. I gave this the "negative" effect too.
We've had a nice day catching up at Mom's. Then it's off to school in the morning.