Leaf capsule mystery

Yesterday when I was putting together my "camera on a pole" setup, I grabbed a length of electrical conduit that had been sitting on the driveway for a few weeks. I noticed that there were a lot of small leaves stuck in one of the ends of the tube.

When I removed the leaves, this is what I found.

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The leaves are from a black locust tree, and there were several layers of them wrapped around this little capsule:

If you look closely, even the round "door" of the capsule is made from a leaf:

I'm not sure what's in here, but I'm assuming it was planning on spending the winter in the pole.

I'm guessing that the leaves are held together with silk of some sort. It's a really nice job -- it looks quite waterproof, and the extra layers of leaves would help to insulate it.

So what made this? Is it a spider? A butterfly or moth caterpillar that has pupated? As much as I want to know right now, I won't remove the remaining leaves. I don't want to damage the critter or reduce its chances of surviving.

I think the only way to find out what is in here is to put this capsule into a jar and see what eventually emerges. Since I'm not absolutely certain that its inhabitant was planning on spending the winter in here, I'll leave the jar on the counter until it starts getting colder. Once it stays pretty chilly I'll move the jar into the refrigerator. 

I wonder if I should move it to the freezer to more closely mimic the outside weather? Probably not, since I've kept praying mantis eggs in the refrigerator all winter and that kept them dormant just fine. The freezer would probably dry them out too much.

I'll let you know if there are any new developments, but you probably won't be hearing about this again until the spring.