I love your Polka!! It's a climber isn't it? Is that a raspberry near the nest or is it some sort of forsythia berry? I don't know anything about forsythia LOL. Carol

Ok, apparently that white thing's a tailor bird nest. Still don't know whats destroying the leaves though.

Ilikewinter: That is clearly a mantis egg case. Keep it in a cool, dark place over winter, then when the sun warms things up in spring, take it outdoors and hundreds of tiny mantises will emerge. These are valuable beneficial insects, and people pay a lot of money to buy them. It is best if you do not remove the egg case from the pepper branch. I find them nearly every fall on my pepper plants, which seem to be one of their favorite places to leave eggs. One year, I took an overwintered case and placed it in a fishbowl with screen over the top. In May, the little rascals emerged in large numbers, looking for all the world like green mosquitoes. I released them out in the orchard. Don Yellman, Great Falls, VA

Actually, after the leaves fell a few weeks ago, we found a very similar nest in an ornamental cherry tree right outside a kitchen window. Very round, rather small and the cup quite deep. Like your picture it was sort of crammed into the crotch of several branches for security. The weaving is quite thick and extensive on ours with a lot of material in it....not sack-like at all like an oriole's. Thanks for jogging my memory, I had intended to find out what type of bird lived right under our noses all summer and not be noticed.