Unknown spotting

Description:

Bizarre insect with a heap of what seems to be rubble piled on its back. The rounded mound is mostly white (spider silk?) and seems to contain bits of leaves. Sitting on a leaf or stem, the insect looks like a bird dropping. I could hardly believe it when I saw it move. It was found with a bunch of leaf-hopper nymphs, so it could be related to those.

Habitat:

Daylily stem and leaves in a flower bed in my yard. Sharing that stalk with about ten hopper nymphs.