Written by Curator Emeritus Bob Glotzhober
How often does Ohio end up with a species of wild animal new to the state that is not an exotic invasive species? It is pretty rare, but it does happen. Recently Ohio added a dragonfly to its list of inhabitants which has never before been found in Ohio. The dragonfly new to Ohio is known as the Swift Setwing (Dythemis velox) and it is a member of the Pond Skimmers family, the Libellulidae. While not previously known from Ohio, it is native to North America and can be found as close as southern Illinois and southwestern Indiana. Retired entomologist (and avid volunteer at Cedar Bog Nature Preserve) Jim Lemon found it on private property near Urbana, Ohio in Champaign County. The property is in a rural location only a few miles from Cedar Bog Nature Preserve. The official count of species of Odonata (dragonflies and damselflies) in Ohio now rises from 163 to 164. (There is one additional, potential species of yet un-named River Cruiser, genus Macromia, which is not included in this count. For a complete listing and distribution maps of Ohio species, go to the Ohio Odonata Society website of Marietta College at: http://www.marietta.edu/~odonata/
Jim has been assisting another volunteer, Rob Liptak, with a monitoring program for butterflies at Cedar Bog. Rob established the Butterfly Monitoring program at Cedar Bog about five years ago, as part of the state-wide Butterfly Monitoring Program, sponsored by the Ohio Division of Wildlife and the Ohio Lepidopterists. (Note: Lepidoptera is the order of insects which includes both butterflies and moths.) Both Rob and Jim have started expanding into dragonflies and damselflies as they walk the Cedar Bog property in a systematic fashion.
Recently Jim got permission to survey some pond areas on a piece of private property. On July 25th Jim found a dragonfly he could not identify. Jim took several photos of it in the wild, then captured it and took several photos in hand before releasing it. The photos were sent to me to help the ID. While the initial photos were pretty good, I could not see all the features I wanted to, and could not come up with a positive match. I sent the photos to Dennis Paulson, a long-time colleague in the Dragonfly Society of the Americas, and author of the 2011 book, Dragonflies and Damselflies of the East (Princeton Field Guide Series). Dennis has traveled a lot and is expertly familiar with all the dragonflies in North American and many beyond. He identified the photos at once as the Swift Setwing.
Dennis also indicated that he believes this southern species seems to have been expanding northward. I had seen this species once, back in 2001 in Texas and was embarrassed that I had not recognized it but with 450 dragonflies and damselflies in North American north of Mexico, perhaps I have at least a partial excuse.
There are four species in the genus Dythemis (all known as setwings) in the United States, and the other three are southwestern in their distribution. The Swift Setwing reaches eastward in the southern states, reaching all the way to southern Virginia. The closest known populations to Ohio are in extreme southern Illinois and southwestern Indiana, more than 200 miles away!
The Setwings are an interesting group of dragonflies. They spend a lot of time perched, typically on the tip of branches and frequently with their wings angled down and forward and their abdomen slightly raised. Sid Dunkle and Dennis Paulson came up with their English name of setwings from this posture, which reminded them of a sprinter at a track meet on the blocks in the ready, set, go position.
Despite the excitement over a new dragonfly in Ohio, there is a bit of a mystery around the discovery of the Swift Setwing in Champaign County. In his book, Paulson describes their habitat as: Streams and rivers with slow to moderate current, less often ponds and lake shores. Usually wooded or shrubby banks. The Ohio location is along a lake which has some shrubby areas, but mostly mowed lawn surrounding it. The habitat partially fits Paulsons description, but it is not the preferred wooded streamside. If this is a brand new expansion of range for the Swift Setwing, would it not be more likely to first establish itself along the preferred habitat? The Mad River is not far from the lake where the Swift Setwing was found, so Jim and I plan to explore the Mad River in the near future to see if there are more Setwings along that river.
We have never seen more than one male on one day but the sightings have been on July 25th, August 2nd, August 3rd, August 7, and most recently on August 9th. Two of the sightings was at least 200 yards away from the other sightings. Is this a single male that is wandering a bit, or multiple males with separate territories along the lake shore? While adult dragonflies might survive individually for up to a month or more, they are very susceptible to predation by birds, spiders and fish. Spotting individuals over a period of two weeks strongly suggests more than a single individual, but does not by any means prove there is more than a single individual. Further, not a single female has yet been spotted. So a lot survey work needs to be done to decide if we have a single male, blown north by a storm, or perhaps a small but established population. Leading a little bit of evidence toward the later, when Jim saw the first individual on July 25th, it was a teneral a term that describes a dragonfly recently emerged from the larval form. If the male Swift Setwing emerged from the lake waters or nearby Mad River, then last year a there had to have been a female which laid eggs in these Ohio waters. Jim and I, and perhaps some others, will be watching for evidence to help determine which scenario is true. Stay tuned for an update if and when we find more individuals!
Curator Emeritus of Natural History