Dragonfly Researcher Visits Door County

There is no shortage of environmental significance that Door County offers. Earlier this year, the coastal wetlands were recognized as being globally significant, in ranks with the Florida Everglades and Chesapeake Bay. Buzzing deep in the woods of these wetlands, the Hine’s Emerald Dragonfly makes its home.

The Hine’s Emerald Dragonfly has been endangered since 1995 and only recently began to show a promising return thanks to Door County’s unique environment.

“The Hine’s Emerald was thought to be extinct but it was rediscovered in Door County,” said Chris Anderson, Director of the Nature Conservancy in Minneapolis. “The Door County population is the stronghold.”

Anderson explained that most efforts to reintroduce the endangered dragonfly elsewhere have their roots in Door County, where the relatively large population allows for some experimentation.

“Because Door County has the largest population, they’ve been able to take some risks and learn how to do it better,” said Anderson, referring to reintroduction of the species in places like Illinois and Southwest Wisconsin. “Door County is kind of the outdoor laboratory for how to save the Hine’s Emerald Dragonfly.”

Dan Soluk is the lead scientist in this outdoor laboratory. Soluk has been researching the Hine’s Emerald for nearly 15 years, which has included several trips to Door County.

“Door County has been an essential place for studying the species,” said Soluk. “We can do ecological studies of things that aren’t really possible. We can go up to Toft Point in an afternoon and in half an hour we can collect a couple thousand eggs.”

Soluk explained that at the Des Plaines River Valley on the outskirts of Chicago, where they have tried reintroducing the species, the small population makes it hard for his team to even find the insect.

To reintroduce the Hine’s Emerald, Soluk collects eggs from the insect and raises them in captivity. Although controlling the environment may increase the yield of surviving dragonflies, it is not a quick venture.

“The biggest problem is that we need to raise them on the same timeline that they do normally. The Hine’s Emerald Dragonfly has a very long life cycle. The larvae spend four to five years from egg to adult,” said Soluk.

Since the dragonflies only live for about six weeks in their adult, aerial state, they spend more than four years as sedentary larvae, maturing in shallow waters of Door County’s wetlands. This makes them susceptible to groundwater quality.

Poor groundwater quality due to surface level contaminants has been the leading danger to the Hine’s Emerald.

Although Door County boasts the most abundant population in the world, it has one drawback.

“Although there’s a lot of number, the Door County population lacks genetic diversity,” said Soluk. “Even though the Chicago population is between only 1,000 and 3,000, they are very genetically diverse.”

This diversity is important in reacting to abrupt changes in the environment. With Door County’s population of dragonflies being so similar, a disease or groundwater contaminant has potential to wipe out the entire population.

Populations in Chicago and Southwest Wisconsin, however, are genetically diverse, making them more likely to adapt to changing conditions.

The genetic makeup of Door County’s population also poses an issue with bringing the species elsewhere. Despite the large numbers in Door County, Soluk and his team cannot just catch dragonflies and bring them to a new location. If they want to increase numbers in a new habitat, they must take dragonflies from the habitat and raise the larvae over five years before reintroducing them.

Soluk is careful not to experiment on habitats with such a low population for fear of harming the few dragonflies that are alive.

One part of Soluk’s stay in Door County will consist of ground-truthing the habitat. Aerial land use maps provided by the county list where a likely habitat for the Hine’s Emerald might be.

“That’s an assumption made on aerial maps,” said Anderson. “Dan is taking those aerial maps and he’s ground-truthing it. He is going to go in and walk to that specific area and he will verify that, ‘Yes this is Hine’s Emerald habitat.’”

For the next two weeks, Soluk will be based at a facility in Rowleys Bay while spending a lot of time at The Ridges Sanctuary and Toft Point. He will study the dragonfly behavior in hopes of providing the US Fish and Wildlife Service with enough information so they can develop their own larvae in hatcheries.