Just before noon on a Thursday in mid-July, a caravan of dust-covered cars and Jeeps shimmies down a skinny dirt road through a chunk of Upper Peninsula forest just north of St. Ignace. The sky disappears as the road narrows into a tunnel of trees, branches from the pines and cedars scraping along the windows with muffled screeches. About three miles in, the squeeze of the roadside scrub halts the caravan. The drivers cut the engines, car doors creak open, and the occupants scramble out into clusters of chicory and black-eyed susans.

With cameras dangling from their necks and nets slung over their shoulders, they file down an old logging trail, picking their way along the corduroy lines of decaying white cedars laid flat in the ground. Their ultimate destination? A sunny, spongy, biting-fly-ridden marsh, a likely home of the Hines emerald — the only dragonfly in the nation to make the Federal Endangered Species List.

The folks here are part of a Hines emerald workshop, biologists, entomologists and odonatologists — people who study dragonflies — from museums, universities, departments of natural resources, the Fish and Wildlife Service and such. They’ve come from Michigan, Indiana, Missouri and South Dakota, descending together on this mucky patch of U.P. marshland with one mission in mind: To unravel the mystery that is Hines emerald dragonfly.

In decades past, the Hines emerald has been documented in Indiana, Ohio, and as far south as Alabama. Today it’s known only to live in four states: Illinois, Wisconsin, Missouri and Michigan. In Michigan, it’s been recorded in 11 sites in Mackinac County, one site in Alpena County and two in Presque Isle County.

The Hines is picky about habitat — sticking mostly to wetlands, the marshy margins of small, sluggish streams that are dominated by grasses and sedges, and near forests. The common denominator for its favorite frolicking grounds has long been considered thin waters and thin soils with underlying bedrock of dolomite, a mineral made of calcium magnesium carbonate. But in Michigan, the Hines has thrown odonatologists for a loop. The Hines here also hangs in places that are marly and full of clay, hyper calcareous, and with shallow but sometimes vast sheet flows of water and, on occasion, little vegetation.

Figuring out what the Hines likes in a site is important; after all, you can’t protect a species unless you protect its habitat. But to identify the species’ habitat, you must first track down the species. As the dragonfly hunters fan out across the muck, their billowing nets aglow under the noon sun, that’s exactly what they intend to do.