April 10, 1997
Washington state’s new official insect is a little bizarre, but also darn marvelous, says UW professor
It begins life as a miniature underwater jet engine and ends its days as an aerial dive bomber gathering up its prey in a highly developed “cow catcher.” If that sounds more like the Empire striking back than nature, don’t be fooled. It’s the green darner dragonfly, and it has just been named the official insect of the state of Washington.
The green darner, says University of Washington zoology professor John Edwards, “is a simply marvelous animal. It’s both sophisticated and slightly bizarre.”
The green darner is just one of the 407 dragonfly species found across North America and the 71 common to the state of Washington. It’s official name is Anax junius, and it gets its common name from its pointed, bluish abdomen, resembling a thick darning needle. The same insect has also been known through the ages as the horse stinger (although it doesn’t sting) the mosquito hawk (because of its incredible ability to catch mosquitoes) and the snake doctor (perhaps because it sheds its skin).
One of the more remarkable things about this dragonfly, says Edwards, is its survival mechanism during the one to five years it spends underwater as a larva, or nymph. Its rectum is a jet propulsion mechanism, enabling it to dart away from hungry fish by alternately sucking in and then ejecting water. Its stereoscopic eyes help it latch on to its victims, which it grasps with an elbow-like, hook-tipped mask that shoots out from under its head.
During its life, the green darner will shed its skin 10 to 15 times, the final molt coming when it climbs out of the water and emerges looking something like a crumpled plastic bag. It slowly inflates itself by swallowing air, and completes the transition by exuding an enzyme that turns its soft, vulnerable body into a hard outer shell. “It’s just like mixing an epoxy glue that turns the skin hard,” says Edwards.
The rest of the bug’s life lasts just one summer (if it isn’t eaten by a predator such as the redwing blackbird). But, notes Edwards, even this short span is remarkable.
For a start, the dragonfly will fly tens of miles (it speeds along at close to 30 miles an hour) from its watery birthplace in search of flying insect prey, such as mosquitoes, which it scoops up with its basket-like legs. The mating ritual begins with the green darner hovering over its aerial territory and swooping down on intruding dragonflies. The idea is to keep the area clear of competitors so that a willing female can be attracted to its perch.
Part of the dragonfly’s appeal to researchers, says Edwards, is its very ancient position in the planet, outdating the dinosaurs by millions of years. The fossil record shows there were dragonflies in paleozoic times. Only they were somewhat larger than the green darner’s modest five inches in length, with a wing span of two feet.
Naming the green darner the state insect is, Edwards believes, “a good way of informing people about this wonderful insect, as well as raising consciousness about the value of insects as a whole.”
Edwards can be contacted at (206) 543-8829, or hardsnow@u.washington.edu
The Burke Museum on the UW campus has a permanent display of all 71 of the species of dragonfly found in the state, including the green darner.
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