Thursday, May 18, 2017

Swamp Darner


Female Swamp Darner*  - Tonya Smith
From Tonya Smith, MN
As our group of wildflower enthusiasts were identifying native flowers in the vicinity of Bull Creek, Kevin Firth and his daughter were collecting specimens for Springfield Botanical Center's Butterfly House. He netted this impressive dragonfly which caught all of our attention. As I observed this extremely large dragonfly close up, Steve Irwin's voice echoed in my head, "Isn't it a beauty!" Meet Swamp Darner ... this dragonfly has brilliant blue eyes, complimentary bright green thoracic strips and abdominal rings on a brown abdomen and four powerful wings.
  Dorsal View - T Smith
Swamp Darner (Epiaeschna heros) is one of the largest dragonflies in the US measuring between 3 and 4 inches in total length with a wingspan that can reach just under 5 inches. Their range is eastern North America extending west to Oklahoma and Texas. Swamp Darners are one of approximately 15 species of dragonflies (out of about 400) that migrate. They move down the Atlantic Coast in large numbers, sometimes as far as Mexico and the Bahamas. Speaking of migration, the Migratory Dragonfly Partnership (MDP) have learned timing, intensity and relative species composition of dragonfly migration varies annually even among species known to be regular migrants. MDP is relatively young being established in 2011.

Swamp Darners prefer plant filled water in shaded woodlands, but it also expands its feeding to habitats that are not tied to water. Sometimes it will fly into a building through an open window perhaps seeking out it's naturally shaded haunts. It will feed both high in the air and at ground level. These very large dragonflies will also dine on species of dragonflies smaller than themselves. Swamp Darners are often seen feeding in swarms on flying insects at dusk. With the use of their magnificent compound eyes they can easily grab prey out of the air. The Darners (Aeshnidae) claim to fame is having the most complex compound eyes in the insect world.

Blue eyed male - Delmarva Dragonflies
The tail like appendages are long in both sexes. The male appendages are complex and distinctly hairy. The female appendages are flattened appearing stalk like. Apparently, the male Swamp Darners don't have any interest in defending or patrolling territories. The female's egg laying apparatus is called an ovipositor. It includes two pairs of blades that she uses to penetrate wood or plant stems.

Ovipositing Swamp Darner - Walter Sanford
The female Swamp Darners lay their eggs in damp and dry locations such as in mud, in trunks or soggy bark of standing and fallen trees, in stems, and at drying ponds.  A lot more detail about the process is in this annotated version of Walter Sanfords photograph above.

Some dragonfly tidbits worthy of mentioning:
Dragonflies have been used as tools to assess the biological health of aquatic habitats and to detect levels of heavy metals such as mercury. They are also considered model organisms to assess the effects of global climate change.

Is there an endangered dragonfly? Yes! Hine's Emerald Dragonfly (Somatochlora Hineana) was listed January 26, 1995. It's range is in Illinois, Michigan, Wisconsin and in our wonderfully diverse and beautiful state of Missouri. It's survival depends on spring-fed shallow water to breed. The U.S. Fish and Wildlife Service has a recovery plan that describes and prioritizes actions needed to help the dragonfly survive.

Even though I have never observed this behavior, I would assume with six legs (like any other insect) a dragonfly could walk. Wrong!  Dragonflies have been in existence for over 300 million years. Long before the dinosaurs walked the earth, Griffenflies were their prehistoric ancestors. The largest dragonfly fossil found had a wingspan of 2 ½ feet.

If you're planning a dragonfly hunt, be sure to download the Dragonfly and Damselfly Field Guide and ID App by Birds in Hand, LLC.  To manage habitat for dragonflies you can go to the Xerces.org site.

* The female Swamp Darner has darker blue-brown eyes, a thicker abdomen and no epiproct.

Other Dragonfly sources:
Odonatacentral.org/
Buglady at Uwm.edu/field-station
See Swamp Darner ovipositing in action in this Youtube video.

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