Summer 1999

[TEXT ARCHIVE WEB-PUBLISHED MARCH 2002.
ORIGINAL PRINT PUBLICATION DATE: SUMMER 1999.]

Hine's Emerald Dragonfly :
A Globally Rare Gem

By Patricia K. Armstrong

The Hine's emerald dragonfly (Somatochlora hineana) may be the most endangered dragonfly in the United States. Illinois placed it on its endangered species list in 1991, and the federal government listed it in 1995. So far it is known to exist in only three locales: Door County, Wisconsin, the eastern Upper Peninsula of Michigan, and within one mile of the Des Plaines River in northern Illinois.

The Hine's emerald is large as dragonflies go, measuring 2 to 2.5" long with a wingspan of 3.5-3.75". It is characterized by large, bright green eyes, a dark brown and metallic green thorax with two creamy-yellow lines, and transparent wings with amber tinting at the base of the hind wing. The nymph or naiad (aquatic larva) is about 1" long and brown. It is oval shaped and densely covered with coarse hairs on which algae and debris accumulate, making this dragonette look like a dirt ball with legs.

The nymphs live for two to three years in narrow, slow-moving rivulets in marshes. Prime habitat is cool, shallow (only several centimeters deep), slow-moving water, usually found in spring-fed marshes, fens, or seepage sedge meadows. They move by walking on their six long legs or they can squirt water out of their anal opening and thus be jet propelled. Nymphs prey mostly on fly larvae and crustaceans, but sometimes catch small fish and larval amphibians. The lower jaw of a dragonfly nymph is long and hinged below the chin so it can dart out and grasp its prey with tong-like terminal appendages and pull it back to the mouth to feed. Nymphs, in turn, are fed upon by fish, predaceous beetle larvae, and other dragonfly larvae sometimes even of their own species.

When a nymph is full grown, it crawls up a plant stem out of the water, and the adult emerges through the split skin of the nymph's back. It is soft at first, a tempting morsel to frogs or birds. Adult dragonflies emerge in late June or July and live only a few months until frost. They eat insects — mosquitoes and flies — on the fly. Adult males patrol their territories, lunging forward to scare trespassers off. They chase other males away but pursue females with a different objective in mind.

Dr. Everett (Tim) Cashatt of the Illinois State Museum and other scientists have been studying the Hine's emerald dragonfly since 1988. They visited 106 sites in Illinois, Ohio, and Wisconsin and located breeding populations in Door County, Wisconsin, and the Chicago area. The Hine's hasn't been seen in Ohio since 1961. Finding adults cruising over the cattails is hard enough, but it took three years of searching to discover the nymphs in the water. Chicago Wilderness breeding areas include: Emerald Fen at Waterfall Glen in DuPage County, two sites in Cook County, and five sites in Will County. Others studying these creatures include TAMS Consultants, Inc., the Wisconsin Nature Conservancy, and Dan Soluk of the Illinois Natural History Survey.

The US Fish and Wildlife Service and others are currently working on a recovery and management plan for the dragonfly, and the Forest Preserve Districts of Cook, DuPage, and Will Counties are keeping little streamlets open by cutting back cattails and pulling out watercress. In this pampered habitat, the female dragonfly lays her eggs one at a time, flicking her tail into the water.

So, if you would like to see this rarest of our Chicago Wilderness neighbors, pick a sunny morning in July when it's warm and not windy. Grab a pair of binoculars, and go for a walk along Division Street at Lockport Prairie in Will County. Perhaps, if you are lucky, you will catch a glimpse of a metallic green and brown mini- helicopter with emerald eyes and amber wing bases, living the good life in Chicago Wilderness.