I don't see any bugs, but the tree is not as leafed out as it has always been, and I'm noticing a lot of stems that had leaves a few weeks ago that are empty now. Leaves aren't on the ground, so I assume they're getting completely chewed off. Eventually the stems turn brown and dry out, but it's happening on green stems. Any ideas?
Cultural issues could be issues with watering (too much/too little), issues with soil, fertilizer, etc. I just think the way the tree didn't leaf out well in the first place and the way the stems turn brown after the leaves disappear seems more like a cultural problem or a disease of some sort rather than something eating the leaves.