Emeralds of the Ozarks

By Bob Gillespie, photographs by Richard Day | June 17, 2014
From Missouri Conservationist: Jul 2014

Here be dragons.

Winging silently over murmuring Ozark streams; fluttering above open pastures and meadows on midsummer dawns, their wings glittering in the eastern light; found tucked away in some forgotten forested cove, a cl spring seep found there to call home; or skimming just above the treetops looking to feed on a warm still evening.

“Here be dragons” the map would read. In the country around Marct, Bixby, Salem, Eminence; around the slopes of the St. Francois Mountains; to the lower reaches of the Current River; for many of them the eastern Ozarks is home.

Dragons, indeed. Patrolling, feeding, they often live short, violent, wing-tattered flight seasons defending territories, searching for mates, laying eggs, and succumbing to their place in the food chain.

Dragons, yes, but not the fire-breathing sort that have a predilection for piles of men’s treasures and pretty maidens. The Emeralds of the Ozarks are a group of dragons with compound eyes — extraordinary sensors with more than 30,000 individual lenses, allowing them to be adept hunters of aerial insects. They are equipped with phenomenal visual senses that are sensitive to some parts of the spectrum that man cannot discern.

So these dragons, these Emeralds of the Ozarks, are a group of dragonflies belonging to the genus Somatochlora.

Known fondly as the Emeralds, they are named for their brilliant, emerald green eyes. Six Somatochlora species have been documented in Missouri. We will introduce you to four of them: Hine’s emerald dragonfly (Somatochlora hineana), Ozark emerald (Somatochlora ozarkensis), mocha emerald (Somatochlora linearis), and clamp-tipped emerald (Somatochlora tenebrosa). The other two species, fine-lined emerald (Somatochlora filosa) and treetop emerald (Somatochlora provocans), are seldom observed in Missouri.

Hine’s emerald dragonfly is one of Missouri’s rarest dragonflies. It is listed as endangered both at the federal and state levels. Hine’s emerald dragonfly is so imperiled because it occupies Ozark fens, a specific wetland type that is itself rare in Missouri. This dragonfly belongs to the Corduliidae family, which contains 384 species, 39 of which are Somatochlorans; 26 occur in the United States.

Hine’s emerald dragonfly has brilliant green eyes, dark metallic green coloration to the thorax, and an overall imposing matte black body, and two distinct yellow “tiger stripes.” Adults of the species are nearly 3 inches in body length and have a wingspan approaching 4 inches.

All the emeralds are aquatic insects that spend the majority of their lives developing in wetland habitats as an aquatic nymph or larvae. Hine’s emerald dragonfly may spend from two to four years in the larval stage. The dragonflies that we observe on-wing are the adult stage, and for Hine’s emerald dragonfly this stage may only last five to six weeks. This is the last stage of the dragonfly’s life, and the stage responsible for reproduction.

The surprising thing about Hine’s emerald dragonfly larvae is that they spend a great deal of time in crayfish burrows. Crayfish burrows are often abundant in Ozark fens and are characteristically tremendous deep warrens of subterranean tunnels filled with water. Scientists believe that the larvae seek refuge in the burrows, especially as the dry days of summer and fall cause the water to dry up in the fens. The developing Hine’s emerald dragonfly larvae retreat deeper and deeper into the tunnels, moving with the water table to survive.

Hine’s emerald dragonfly is a species restricted to areas where limestone or dolomite bedrock lies close to the surface. They occupy wetland habitat types characterized by sandy or marly saturated soils, wetlands that are typically associated and sustained by free-flowing springs. Ozark fens, prairie fens, forested fens, seeps, marshes, and sedge meadows are natural communities that support populations of Hine’s emerald dragonfly.

Wetland destruction and fragmentation of suitable habitats are recognized as the main reasons for this species’ endangerment.

Hine’s emerald dragonfly populations are distributed within the eastern Ozarks. This emerald can be observed in pastures that have perennial Spring fed swampy ground with crayfish burrows.

Clamp-Tipped Emerald

Clamp-tipped emerald is a close sister species to Hine’s emerald dragonfly, and it is often difficult to tell them apart unless you study their terminal appendages (tip of the tail end of the body), which just happen to be clamp shaped. The adults of clamp-tipped emerald also have a flight season that begins in the waning stages of the flight season of Hine’s emerald dragonfly. The lives of most Hine’s emerald dragonfly adults have run their course as the hot days of July arrive in Missouri. The short flight season (5 to 6 weeks) of Hine’s emerald dragonfly typically starts in May and peaks in June; clamp tipped emeralds live longer and may be observed into the early fall months.

Clamp-tipped emeralds are slender, dark brown dragonflies with clear wings and swashes of green and bronze reflections to the head and thorax. Clamp-tipped emerald can be observed along small, quiet, flowing Ozark streams and near seeps, springs, and in the same fen habitats as Hine’s emerald dragonfly. Clamp-tipped emerald is more tolerant of brush and trees and can be found readily along wooded stream corridors and forested seeps. This emerald tends to flutter over standing water, often about boot top high, and can be observed hovering in shade and sun-dappled areas of fens or streams, seemingly disappearing and reappearing as one’s eyes try to adjust to the contrast. But when seen, their eyes seem to be backlit with an iridescent piercing green.

Emeralds are not choosey when it comes to prey, pursuing and feeding upon insects (and other flying organisms) that are nearly as large as them, and eating one of their own species is not off the menu. Emeralds routinely feed on the gnats and flies that one might encounter on a walk through a hay field or observe along a stream on a float trip. They are adapted for dynamic feeding efficiency.

Mocha Emerald

Mocha emerald is a more common emerald that prefers dark, tree-lined streams. It can be observed feeding along stream corridors and shaded openings, or in nearby fields or yards, singly or in feeding flights, in the late afternoon until dusk. Mocha emeralds have a chocolate or mocha-colored thorax that has a greenish iridescence but no distinctive yellow tiger stripes like Hine’s emerald dragonfly. Females can be observed tapping the tip of their abdomen directly into the wet mud or shallow water at the edges of streams or puddles — ovipositing (laying eggs). Males will patrol segments of streams looking for females and prey of opportunity.

Emeralds are aerial acrobats.

Situated in the order Odonata, they represent an ancestral form of insect flight. These dragons have two pairs of wings that can beat independently, allowing pinpoint flight directional changes. They are highly maneuverable and adept at intercepting other flying prey, capturing and often consuming them as an inflight meal.

Ozark Emerald

Our most secretive emerald, Ozark emerald is a dragonfly that is not well known to the scientific community. It has been collected sparingly in Missouri and, although sought after, it is seldom seen.

Ozark emerald appears to use very small perennially spring-fed streams in forested habitats. Very limited adult and larval surveys have been conducted for the species in Missouri. Their life history is not fully known, and the population size and habitat requirements are still being researched. Although both males and females have been captured, their larvae have not been observed in Missouri. There is much to be learned about this uncommon dragonfly.

The Ozark emerald can be observed in feeding flights in the late afternoon or at dusk, often over forest roads and open fields, sometimes at treetop height but occasionally close to the ground. It is smaller than its sister species, has a distinctive terminal appendage, has white to cream thoracic striping, and their eyes have more blue than the other Missouri emeralds. So keep a keen eye about you, because here be dragons.

They are the beautiful, rare, and secretive Emeralds of the Ozarks.

Bob Gillespie is a natural resources coordinator with the Illinois Natural History Survey. Formerly the Missouri Department of Conservation’s natural history biologist for the Southeast Region, he was the recovery leader for Hine’s emerald dragonfly. Bob currently chases the beep and promising static of radioed prairie chickens, the dragonfly net set aside for a time. Richard Day is an adjunct research associate in zoology with the Illinois State Museum and has researched Hine’s emerald dragonflies in Illinois and Missouri since 2007. He has been a professional photographer for 30 years.

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