What insects eat elderberry leaves?

One of my elderberry plants was nearly denuded but here's a picture of one that might show the damage better:

I was surprised that the damage was worse lower to the ground rather than up high like Japanese beatles have a habit of doing.

Grasshoppers? That is what those chomps look like to me. Ours gets eaten a bit but that doesn't effect its growth or ability to produce berries. We have a hedge of it and it is maybe more of a wild variety...I'm not sure how it got where it is...It sprouts like crazy from the roots.
I guess, you would see grasshoppers in the daytime though............do you think it's happening over night?

The plants are down by the pond so I don't go down there all that often. We certainly have plenty of grasshoppers around so that's definitely a possibility. I should toss a few grasshoppers to the ducks to see if the ducks eat them. Maybe I just haven't been letting them get down to the pond often enough!

I’d like to know too! Our elderberry bush started looking strange a few weeks ago, first on the sunniest side in the middle upper area. The limbs were defoliated. It has continued to take in almost the entire bush-lower to the ground there are still some full leaves although showing nibbles. Upon inspection, there’s nothing visibly wiggling or jumping. Of course, there are no berries whatsoever. We have some grasshoppers around but other years they were worse and no problem with the elderberries. 🤷🏻‍♀️

I thought they were poisonous to bugs? I remember reading the elderberry leaves could be used as an insecticide tea.

I have grasshoppers on my elderberry but they tend to stay up near the tips of the branches. They don't cause damage like that near the base.