You’ve probably seen a dragonfly flying around this summer, but did you know that by this point most of its life has already taken place in water? Often unseen by human eyes, dragonflies (and many other insects) lead a secret life underwater going through a lengthy and complex metamorphosis.
The dragonfly’s life begins as an egg laid in freshwater. From here, the egg hatches and a dragonfly nymph emerges underwater. This larval stage of the dragonfly’s life can last anywhere from a few months to up to six years! During this time the nymph sheds its entire skin between six and fifteen times. In addition to being the lengthiest part of a dragonfly’s life, the nymph stage is perhaps the most fascinating. While living underwater the dragonfly nymph is an aquatic predator, preying on a variety of aquatic insects and even tadpoles and small fish. To breathe underwater, the nymphs have gills located inside the abdomen. The dragonfly expands and contracts its abdomen to move water over its gills, and can even squirt the water out quickly for a short burst of jet-propelled movement.
The presence of dragonfly nymphs in a waterway can also be used as an indicator of stream health. SPREE summer campers recently learned how to catch and sort this and other macro-invertebrates based on pollution tolerance to determine the health of the South Platte as it flows by Johnson-Habitat Park. The dragonfly nymph is one of the campers’ favorite invertebrates to catch due to its larger size and alien-like appearance.
Unlike butterflies and many other insects, dragonflies skip the pupal stage and go straight from larva to adult. Because of this they are said to undergo an “incomplete” metamorphosis. After the nymph molts one last time, an adult dragonfly finally emerges in the form that most people recognize. Unfortunately, this flying stage of the insects life only lasts a few additional months.
If you want to see a dragonfly in the city, the best place to look is near water. There are many different species of dragonflies you can find that range in color from red to blue, yellow, or green. Typically they will be between 1 and 4 inches in length, but if you lived in prehistoric times, you could have seen some with wing spans of up to 30 inches! Be careful not to confuse dragonflies with their close relative the damselfly though. Both are part of the same subgroup of insects (Odonata) and share many physical characteristics. The best clue for distinguishing the two is that damselflies have hinges that allow them to fold their wings together when resting, while dragonflies do not. The next time you do spot a dragonfly, think about the amazing transformation it’s undergone to get there!