By virtue of sheer numbers, damselfly nymphs rank high on the aquatic menu, available to trout year-round but at their most helpless when struck by the urge to emerge. Damsels, however, don't hatch on the surface film. They migrate toward whatever, in their tiny worldview, constitutes dry land: downed timber, tules, or reeds sticking above the waterline; rocks or docks; or the shoreline itself. There they shed the nymphal skin to become airborne. If you see these papery, castoff shucks, and the presence of adult flies, you're in the right place at the right time.