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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.
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