Mystery exuvia

Exuvia: An exuvia (plural exuviae) is the cast-off outer skin of an arthropod after a moult. In some species the exuvia is eaten soon after the moult, although in other species it is left—the Entomologist's Glossary. 

With a few adult dragonflies starting to show up—it's been a pretty slow season thus far—I'm spending an increasingly amount of time combing the emergent wetlands vegetation for cast-offs: the tell-tale sign that the adult odonate population will be increasing. Dragonflies and damselflies spend most of their lives under water, where they prowl the mud and plants in something approaching armorplate. But come spring and summer, when the increasing light and temperature provide the proper cues, the insects begin the process of metamorphosis inside their shell and, when the time is right, creep up stems and then wait for the rebuilding to be complete. Somehow the adult splits the seam of its skin and crawls out to spread its wings, harden, and get ready for first flight. The exuvia, a perfect model of its adolescence, is what gets left behind.