Notes on the type locality of the Hine's emerald dragonfly
Kenneth S. Mierzwa
The Hine's emerald dragonfly, Somatochlora hineana, was described in 1931, based on a few specimens collected in 1929 and 1930 in Logan County, Ohio (Williamson, 1931). The specimens were collected near Indian Lake, a man-made lake created beginning in 1851 by damming the Great Miami River below the confluence of the North and South Forks (the paper mistakenly refers to the Little Miami River, which is far to the south of Logan County). Today Indian Lake is a typical Midwestern recreational lake, surrounded by a narrow band of State Park and a variety of small businesses tied to water-based recreation. Most of the surrounding land is agricultural, with scattered woodlots and residential areas.
In a remarkably detailed commentary for that time, E. B. Williamson wrote the following about the type locality and the collecting trips that yielded the specimens:
"Ohio State Road Number 117 crosses the North Fork of the Little Miami River north of Huntsville, Ohio. The North Fork is a small stream at the bridge, only a few feet wide and at the season we were there carrying but little water. From its source a mile or two above the bridge it meanders through open and pastured fields in an almost flat terrain of clay soil. Below the bridge there are some willows, adjacent thickets, a few trees, and long, dense growths of lizard-tail through which the water winds its way, often concealed by the abundant vegetation. This condition passes abruptly after about a quarter of a mile into a deep dredged channel about 20 feet wide, which extends into Indian Lake. The upper end of the dredged channel, possibly a quarter to a half mile in length, is in heavy swamp woods, winding through which is the old channel of the creek, now reduced to pools of greater or lesser length.
In this woods is a heronry which Professor Hine visited on June 7, 1929. Leaving the woods along its northern side where it adjoins a golf course, he saw a dragonfly hovering two or three feet above the ground in an open spot under a bush."
A week later, James S. Hine and C. H. Kennedy returned to the site:
"The day was rainy and apparently unfavorable. They failed to find any Somatochlora in the woods, but on visiting the dredged channel they were able to take five specimens resting on low bushes on the woods side of the high bank of earth thrown up by the dredge when the channel was dug."
A total of six specimens were collected in 1929, and only one in 1930 despite searches by a larger group. It appears that the dredge activity had recently disrupted the habitat, and that the collectors found the final remnants of a dying population.
The type locality is easy to locate with the aid of Google Earth and a good local map. The dredged channel is now wider than in Williamson's day, about 50 feet wide almost all the way up to the bridge. Channelization now continues well above the bridge, at closer to 20 feet width.
North of the stream and west of SR 117 is a residential subdivision, and across from this is a narrow wooded band and then open farmland. Downstream is an extensive woodland extending all the way to Indian Lake, and within the woodland several old channel scars are visible. Depending on which channel was active in 1929, the specimens were collected either near the subdivision-woodland boundary, or a short distance into what is now woodland. There is currently no evidence of a golf course, although it's possible that the subdivision occupies the former location.
As with most other known Hine's emerald dragonfly localities, the site is underlain by dolomite bedrock. Unlike most of those other sites, at the Logan County locality the bedrock is covered by anywhere from 150 to 250 feet of glacial till, outwash, and alluvium. Sand and gravel outwash deposits just north of the channel appear to be the most likely source of groundwater, however the site appears to be relatively level. Organic deposits are prevalent between SR 117 and Indian Lake in the vicinity of the channel, with alluvium up channel and clay to the south.
There is no evidence of suitable remaining habitat anywhere in the immediate vicinity of the type locality. Dense woodland, probably swamp forest, persists between the subdivision and Indian Lake, mostly on state park land. The plant species list for Indian Lake State park does mention a few characteristic calcareous wet prairie or fen species, including Deschampsia caespitosa and Cacalia tuberose, both present at many Hine's emerald dragonfly localities elsewhere, but there is no evidence of natural herbaceous openings close to the type locality.
Chasing down additional detail would most likely require a visit to Ohio. The oldest photos I can find online date to 1994, and these show conditions similar to those in the 2006 photo mentioned above. Normally, air photos are available from as early as the mid to late 1930s, and getting a look at these, and at any slightly older maps of the area, would be among the highest priorities to reconstruct historic conditions. Of course, there's no substitute for actually walking the land. Someday I may visit the site in person, out of historical curiosity.