Get to Know Hine’s Emerald Dragonfly
Hine’s Emerald Dragonfly (Somatochlora hineana)
At 2.5” long with a 3.3” wingspan, the Hine’s emerald dragonfly is hard to miss with their bright emerald-green eyes, metallic green bodies and yellow stripes down their sides. They live in calcareous (high in calcium carbonate) spring fed marshes and sedges meadows overlaying dolomite rock like those found in the Crooked Creek subwatershed.
It is an extraordinary insect that relies upon a unique set of conditions to thrive. There are multiple pockets on the Hines Emerald around the Crooked Creek watershed. It is one of the examples of dragonfly nymphs that have a narrow niche of development factors that include a sheet flow of ground water over dolomite bedrock which is present around the Crooked Creek area.
Historically, the Hine’s emerald dragonfly was found in Alabama, Indiana, and Ohio but unfortunately it probably has been extirpated in those states. Today the dragonfly can only be found in Illinois, Michigan, Missouri and Wisconsin.
The Hine's emerald dragonfly is an endangered species. Endangered species are animals and plants that are in danger of becoming extinct. Threatened species are animals and plants that are likely to become endangered in the foreseeable future.
Dragonflies in General
According to the U.S. Fish & Wildlife Service, dragonflies play an important role in nature. They catch and eat small flying insects, including mosquitoes, biting flies, and gnats. In its immature stage (nymph), a dragonfly is an important food source for larger aquatic animals such as fish. They serve as excellent water quality watchdogs, are part of our nation's natural heritage and add beauty to our world.
Several factors contribute to it endangered status including habitat loss or degradation. Most of the wetland habitat that this dragonfly depends on for survival has been drained and filled to make way for urban and industrial development. Contamination of wetlands by pesticides or other pollutants also poses a threat. The dragonfly depends on pristine wetland or stream areas, with good water quality, for growth and development. Development that decreases the amount or quality of ground water flowing to the dragonfly’s habitat threatens its survival because it depends on spring-fed shallow water to breed.
Dragonflies and Damselflies go through a three-part metamorphosis life cycle. They deposit their eggs in water or vegetation in the water and it takes one to three weeks for eggs to develop and hatch. A nymph emerges and goes through numerous molts, on average 12 to 13, over a time period of five weeks to seven years depending on the species. Most nymphs in Illinois are in this stage for one to two years.
As nymphs, they spend the majority of their time under water. As they molt and grow larger under the water they develop wing pads, and eventually, when they are fully developed, they emerge out of the water in vegetation or rocks and break through the skin –similar to a cicada – and the adult emerges. After hatching they pump a substance called hemolymph, which functions similarly to blood, through their the wings and body, taking the shape of adult dragonflies. They then live two to six weeks on the wing as adults depending on predation and weather.
They rely heavily on water quality and can be susceptible to hydrologic changes depending on the species. Since they have been around since the Triassic and Jurassic periods, and since almost all their development is in the water, dragonfly nymphs can give an accurate assessment of water quality, flow rate, and dissolved oxygen levels of water.
To find out more about the Hine’s Emerald Dragonfly, check out Inside, Out & About Crooked Creek podcast that features an interview with Marla Garrison, a renowned dragon- and damselfly expert and author of “Damselflies of Chicagoland, A Photo Field Guide.” Garrison is on the faculty at McHenry County College.