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Into the field | Searching for the second stage
What's ahead for the Hine's? | Learn more about dragonflies
Today I saw the dragonfly
Come from the wells where he did lie.
An inner impulse rent the veil
Of his old husk; from head to tail
Came out clear plates of sapphire mail.
He dried his wings; like gauze they grew;
Through crofts and pastures wet with dew
A living flash of light he flew.
– "The Two Voices," Alfred, Lord Tennyson, 1833
Meet Number Six, Somatochlora hineana, a male Hine's Emerald Dragonfly. He has a wingspan of 3.5 inches and like many other members of the Somatochlora genus, has brilliant bright green eyes. But there is one key difference – this Somatochlora is federally endangered, and the largest population in the world is in Door County. Within a 36-mile stretch of the county there are eight sites where Hine's are believed to be breeding. Adults have been found in a few other areas. All sites are less than four miles from Lake Michigan.
Recently I joined a group of respected odonatologists (dragonfly biologists), naturalists, state and federal employees and zoning administrators for an intensive Hine's Emerald Dragonfly workshop in Door County. Everyone in attendance needed to know what these winged creatures look like, their habits and habitat, and how to identify similar Somatochlora species to prevent mix-ups. The workshop hosts familiarized us with these amazing creatures and shared details on the exciting research being done on dragonflies in the area. I'd like to share some of what I learned from our lectures and field days.
Like all other dragonflies and damselflies, the Hine's goes through incomplete metamorphosis, meaning it passes through only three stages of development – egg, larva and adult. The egg is laid in mid- to late summer and remains in that stage throughout the winter. The larva hatches in spring and emerges in June-July. The larval stage can last three to four years. Sedge meadows and spring-fed marshes are the larva's preferred breeding habitat – and that's where the problem lies. Swampy, wet areas are often filled in or dredged up, destroying vital habitat for Hine's larvae.
After three to four years and up to nineteen molts, the larva sheds its skin one last time (that skin you sometimes find on rocks and sedges is called the exuvia and is a great indicator of populations) and flies off as a newly emerged adult. The adults will live one to two months and their flight season in Wisconsin runs mid-June through August. In that time they will mate, lay eggs and eat mosquitoes, biting flies and gnats, to name a few.
With that brief review of dragonfly biology under our belts, we head to the Ridges Sanctuary in Baileys Harbor for some fieldwork. Many in the group have nets and are experienced in the swooshing technique for capturing dragonflies in flight. Nevertheless, designated, experienced netters with permits are assigned to each group. Me? I've never seen an endangered animal. Will I get to hold it? Is that legal?
The leader of my group, Dr. Dan Soluk of the Illinois Natural History Survey, answers my question during his explanation of the day's events: "You may try to net a Hine's but you cannot remove it from the net. My researchers will do all the handling and tagging." There's mumbling from the crowd of professionals; some seem insulted as if their credibility has been questioned. Soluk continues, "This research as you know is very important to the success of this species, and my permit only allows me to kill 25 in total."
He means that throughout all their research his team can only lose 25 dragonflies; once that number is reached the research stops. He is not killing the insects intentionally, of course, but accidents happen. Sloppy net work can decapitate and de-wing dragonflies and butterflies. I suddenly prefer to set my net aside and watch others do the swinging. I do not want to become a member of the Twenty-Five Club.
In groups of ten or so, we search the sanctuary's swales and paths. Suddenly every subtle movement becomes larger than life; senses are heightened when you are on the lookout. Butterflies become dragonflies, flies become dragonflies. "One's coming your way!" someone shouts down the path. "We missed him, we think it's a Hine's."
The dragonfly cruises up and over my head, but I have time enough to enjoy its passing. "Coming your way!" I shout to the crew ahead of me. What an amazing experience, a group of biologists enjoying a beautiful day, exchanging information and stories, strolling along chasing dragonflies! My thoughts are interrupted by the hum of a net through the air and a triumphant "I got one, Susan, get ready!" Susan is one of the researchers working in the county for the summer. She gently removes the dragonfly from the net, identifies it as male, and determines whether or not it is a Hine's.
This is where it gets fascinating.
With dragonflies, especially those of the Somatochlora genus, distinguishing characteristics can be as subtle as a triangular vein pattern in the wings or the clasper position of the male's terminal appendage. To make matters more interesting, there's a dragonfly that looks a lot like the Hine's. It's called Somatochlora williamsoni and is found (but not in abundance) in Door County. Of course Susan and many others in the group can make a positive ID rather quickly without too much study of the specimen. "This is a Hine's," she says.
We all crowd around. "Look at those eyes!" "Now that is emerald green!" Susan asks one of us to write down various data, the time of day, what the dragonfly was doing and where it was caught. She gets out her tagging instruments. With an adhesive made only in Germany that's mostly used for marking honeybees, she dots the glue onto the left side of the thorax behind the eye, then carefully places a tiny round bead into the glue. Each bead is numbered, and will help researchers track the insects, discover patterns, reveal possible new sites of habitation and perhaps provide new information on the adults' life span.
The tagging process ends in less than a minute. Number Six is released but decides to sit on Susan's finger a bit longer, possibly wondering what just happened, maybe even enjoying the new look. After realizing he is being watched, he flies off down the trail. Our eyes follow until we see him no more.
The next day we focus on the larvae. Our nets are replaced with rubber boots. We drive to prime Hine's habitat: wet, shallow, cool sedge meadows. Thunderstorms are off in the distance. We walk until we are surrounded by the light yellow-green of sedges, the dark smooth green of bull rush and the airy dots of pure white marsh bellflower. My feet are getting sucked into the muck. I hear that familiar slurping sound one hears before losing a boot or sandal to the bog. A gentle rain begins. No one goes rushing to cars. We are looking for exuvia.
Insect exuviae can be found many times during the year. Cicada skins can be found in bark, high up on tree trunks. Mayfly skins can be found anywhere, even on clothesline posts. A dragonfly larva is a bit different. It is an aquatic insect, and often does not travel too far from water to molt, maybe a few feet up a reed or onto a rock or old stump. We search and search. I find a few exuviae on reeds but none is a Hine's.
Dr. Soluk has discovered the Hine's larva has a curious relationship with another creature of the wet meadow, the crayfish. The life span of the larva can be as long as four years, and many shallow meadows dry right up around the end of August. When that happens, the larvae seek refuge in the moist burrows of crayfish. Why the crayfish don't eat all the larvae is a mystery, but enough larvae hide out safely until the wet season returns.
To find a crayfish burrow and remove a larva without destroying its (and the crayfish's) refuge, we stick our fingers in the water and feel around for a burrow. Sometimes the crayfish let us know we've made contact by extending a "handshake." Ouch! Then we pump out the contents of the burrow and begin the painstaking job of sifting through the muck, counting larva that can be placed in four size classes from tiny to large. We place everything back into the burrow as carefully as possible, hoping to avoid a parting pinch from the crayfish.
The Hine's Emerald Dragonfly was listed as a federally endangered species in January 1995. It is known to persist in three populations in Illinois, Wisconsin and Michigan. The Illinois population is the most genetically diverse and the Wisconsin population is the largest and presumably most secure. Information on the status of the Michigan population is limited due to its recent discovery. Historically known in Ohio and Indiana, the Hine's is thought to have been extirpated from these states. It has recently been found in a Missouri fen as well.
The Draft Recovery Plan prepared by the U.S. Fish and Wildlife Service hopes to restore the Hine's Emerald Dragonfly to six viable populations, each composed of at least three sub-populations of 500 reproductive adults.
It won't be easy. The species occupies marshes and sedge meadows fed by calcareous groundwater seepage and underlain with dolomite bedrock – rare habitat becoming even scarcer as more acres are lost to agriculture, development and quarrying.
A first step in protecting the Hine's is to learn more about its precious habitat. So build a visit to dragonfly haunts into your next Door County visit. Take a walk along the Mink River. Stroll through the Ridges Sanctuary. Hike by Mud Lake. You may be rewarded with a glimpse of bright emerald eyes and a display of aerial agility and beauty on amber wings.
Julie Hein-Frank is a DNR naturalist at Newport State Park and the C.D. Besadny Fisheries Facility in Door County.