This buddleia plant at the arboretum has some kind of larvae that "glues together" the new young leaves on the end of the plant stems, and lives inside there, eating the leaves as it hides.
I pulled a few leaves apart and this is what's inside. A small and very squirmy larva. I brought some home, still glued inside their little homes. I am waiting to see what they will turn into. It's been over a week, and I'm not even sure if they're still alive in there.