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Darners: The Northwoods' largest dragonflies

A close-up of this male Canada Blue Darner shows the distinctive thorax stripe.1 / 2
This is a full-length view of a young teneral Common Green Darner. (Photos by Jon Weber/For the Enterprise)2 / 2

A lot has happened locally in the dragonfly world since my column about the mass spring emergence ran on June 2. I'll label most of that activity as "Act 1." Now I'll turn to "Act 2" in which Darners have an important role. What exactly are Darner dragonflies?

Generally, they are the largest dragonflies we have around here. Their two large eyes are squashed together. (Other families of dragonflies have eyes that barely or don't even touch each other.)

Their long abdomens inspired their generic name of "Darner." They resemble the darning needles once commonly used to repair holes in socks and clothing.

However, the long abdomens created the false impression they were "stingers," like those possessed by wasps and hornet, and should be feared. Rather, their abdomens were designed for digestion and reproduction, not stinging!

When not hunting, Darners generally hang vertically from branches and twigs. That's the best time to examine them with binoculars and cameras having telephoto lenses. You'll be most successful if you keep your distance. That's because dragonflies, especially Darners, are very wary. They won't hesitate to fly from perches if you invade their comfort zone.

Common Green Darner

Beginning in mid to late summer, young adults, known as "tenerals," start emerging. Readers who walk in fields and meadows at those times have undoubtedly "spooked" them from the vegetation and grasses where they were resting.

Most will be southbound to the southern U.S. They will foster a generation there that returns to the north next spring. Since keeping track in 1997, I've seen returning adults as early as April 1, last departing tenerals as late as Oct. 29.

At Hawk Ridge in Duluth, greatest concentrations of migrating American Kestrals have been observed dining "in-flight" when the concentrations of Common Green Darners are at their greatest.

However, they pose a Northwoods mystery. Most appear to have a migratory generation while some appear to be stay-at-home locals who don't migrate. University of Minnesota doctorate candidate Ami Thompson is currently trying to solve that mystery.

Blue Darner

There are 11 of the Aeshna species in the Northwoods. They all have two side stripes on their thorax to which their four wings are attached. These stripes have certain shapes, colors and widths that are very helpful in identifying which species is which.

Why are they called "Blue Darners"? Most have blue stripes on their thorax as well as a sprinkling of blue spots on their abdomen. You'll certainly get a "bluish" impression as they fly near you hunting flying insects.

Since 1997, I've observed eight of the 11 species. (Some are so rare or their ranges haven't extended this far yet that I may never see them. But, who knows?)

On Oct. 1, 2015 I was surprised and thrilled to see and photograph a Subarctic Darner. (The Enterprise ran a story and one of my photos from that sighting.) To date, that's my one and only sighting of a Subarctic.

On the other hand, the Canada Darner is the most common Blue Darner I encounter year in and year out. I've seen them as late as Oct. 2.

Any larger dragonfly you still see on the wing this time of the year must be a Darner. Enjoy!

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