Learn about Dragonflies Like the Experts

Photo caption: A female lance-tipped darner ovipositing (laying an egg) into a grass stem adjacent to Grassman Pond – this grass will go dormant and fall into the water allowing the egg to hatch and become a water-dwelling nymph.

We know there is an abundance of insects and other invertebrates that utilize, and often rely on, Madison’s stormwater land. Due to the sheer diversity of these species, it can be difficult to identify the subtle differences between one species and another. Lucky for us, UW Professor and member of the Wisconsin Dragonfly Society, Edgar Spalding, lent his expertise to do a dragonfly survey at the Grassman and Old Middleton Ponds. The data he sent us helps us to further understand the scope of services that Engineered land provides beyond stormwater control.

Spalding’s survey identified 30 species of Odonata order which includes dragonflies and damselflies. Species ranged from common species like the marsh bluet and twelve-spotted skimmer to more rare species like the swamp darner. One very exciting find was of the southern spreadwing, which at Grassman Pond was the first sighting of this species ever in all of Dane County. 

Dragonflies are fascinating creatures. They can live for years in the water as a carnivorous nymph before emerging as an adult. During this period in their life cycle, they have adapted a mouthpart that shoots out to capture their prey. You know the movie Alien? Yes, imagine that… and be glad you are not a tadpole. Their wicked hunting skills allow them to devour other insects (including mosquitoes), tadpoles, and even small fish depending on the species. With their aptitude for keeping insect populations in check, we would surely miss them if they were gone. Some Odonata species are generalists and can live in even the most polluted of waters, while others have very specific habitat requirements and require high-quality waters and sometimes even specific flow rates to make a water body their home.

Photo caption: The empty husk of a common green darner nymph perched on a broadleaf arrowhead leaf at Shady Birch @ Sugar Maple Ponds – nymphs leave the water and break loose from their casing to emerge as an adult with the necessary hardware to fly and obtain oxygen from the air rather than the water.

We do our best to promote the success of all invertebrate species whether they be butterflies, bees, dragonflies and beyond by providing the best habitat possible. Stacking the benefits of habitat provision on top of stormwater control is a great way to get as much out of these urban spaces as possible. Creating and restoring this habitat requires active and targeted management of vegetation. Surveying an abundance and diversity of animal life indicates to what degree those efforts are successful, so we are very grateful to Spalding for his expertise.

If you would like to explore other life forms that we have observed on our ponds and greenways, check out our iNaturalist page.