Gierach Dragon - Streamer. The Gierach Dragon imitates the nymphs of dragonflies. These nymphs can live for up to three years before becoming adults therefore Trout don't see them very often so when they do they make sure that they devour them. The Gierach Dragon is sure to catch trout as it can provide a truly natural movement as the deer hair acts as a weed guard allowing this imitation to sink into areas previously unreachable.