I haven’t got a clue what species these little guys are, and since at the moment, they look like a crumpled up leaf, visual aids aren’t very useful either.
However, it’s clearly some kind of caterpillar that, rather than spin its own chrysalis, has climbed into a leaf and cemented the sides together, making a little leaf sleeping bag. Thinking that a leaf had just gotten stuck together for some odd reason, I tugged at the edges of one on my downy skullcap and stopped immediately, seeing the pale, translucent white skin of something grub-like with black spots. (I hope I didn’t kill it by exposing a bit of it. It’s still there a week later, anyway, so either it’s alive or decaying very very slowly.)
I’ve since found another one on my black-eyed susan–entirely possible that it’s a different species, hosting on a different plant, or perhaps merely a bug of catholic tastes. This time I didn’t open the leaf.
Reading up would indicate that it could be any of dozens and dozens of species of moth or butterfly. Skippers, particularly, make little folded leaf homes, so I’m leaning towards that, since I know there are lots of those in the yard come summer. Or it could be something else entirely. Kinda hard to tell when all you’ve got is a sealed leaf.
Odds are good I’ll go out one day and find the leaves empty, and never know what fluttery beast in the yard made them, but I’m pleased that they found my plants useful anyway.