The downy emerald (Cordulia aenea) is a species of dragonfly. It is metallic green and bronze in color, and its thorax is coated with fine hairs, hence its name. Like most other emeralds, the downy emerald has bright shiny green eyes. Adults are around 5 cm in length, and are in flight from May through July each year. After the downy emerald young emerge from their eggs, they live for three years at various larval and nymphal stages. They are fully grown adults for only two months, during which time they mate and the females deposit their eggs back into the water.