Cobra Clubtail Dragonfly: Big Thorax, Bumpy Eyes, Cobra Hood-Like Club

Summary: North American cobra clubtail dragonfly habitats get big, pale-marked thoraxes and pale-dashed, lined, spotted abdomens with cobra hood-like clubbed tips.

Retired science teacher Walter Sanford shares that two distinctive field markers for the female cobra clubtail dragonfly (Gomphus vastus) are rounded hindwings and two terminal appendages known as cerci; Riverbend Park, Fairfax County, Northern Virginia; May 16, 2016: Walter Sanford @Geodialist, via Twitter May 21, 2016

North American cobra clubtail dragonfly habitats activate rock-, sand-, silt-, water-loving arborists, gardeners and naturalists in distribution ranges from Nova Scotia through Florida, Texas, Nebraska, Minnesota, Alberta, New Brunswick and everywhere in-between.

Cobra clubtails bear their common name for clubbed, cobra hood-reminiscent abdominal tips and the scientific name Gomphus vastus ([crossbow arrow-like] bolt [abdominal terminal segment is] vast). Common names confirm scientific consensus in the Dragonfly Society of the Americas, whose 30th Bulletin of American Odonatology covers broadwing, pond-damsel, shadow-damsel, spreadwing and threadtail distributions. Descriptions in 1861 by Benjamin Dann Walsh (Sept. 21, 1808-Nov. 18, 1869), whose 30,000 insects the Chicago Fire posthumously destroyed Oct. 8-10, 1871, drive scientific designations.

Cobra clubtail life cycles expect medium- to large-sized lakes, rivers and streams with slow to swift currents; rocky, sandy or silty bottoms; and sometimes rocky borders.

April through September function as earliest to latest flight seasons even though June and July furnish wildlife mapping opportunities throughout cobra clubtail coastal and inland niches.

Cobra clubtails go out from night-time resting places until as late as nightfall on food-searching forays, mate-seizing patrols and perch-seeking flights over rocks, vegetation and water. Males have mid-air skirmishes when they head out on simultaneous patrols and hover 2 to 3 feet (0.61 to 0.91 meters) over waterlines in slight breezes. Itineraries involve immobilizing invertebrate prey and investigating feeding, mating and perching options and weedy and woody vegetation within 0.5 mile (0.81 kilometer) of watery breeding habitats.

Ants, assassin flies, biting midges, ducks, falcons, fish, flycatchers, frogs, grebes, lizards, spiders, turtles and water beetles and mites jeopardize North American cobra clubtail dragonfly habitats.

Immature cobra clubtails keep to rock-, sand-, silt- and water-kind camouflage and wide bodies even though adults know green eyes and black, green, yellow, yellow-green coloration.

Incomplete metamorphosis leads from round eggs loosened intermittently into water, after egg-loaded females leave shoreline perches, to immature larvae, naiads or nymphs and to molted tenerals. Immature, little adult-like, multimolting nonfliers metamorphose into shiny-winged, tender-bodied, weak-flying tenerals that master permanent colors and physical and sexual maturation, mate and manipulate eggs into ovipositing sites. Aphids, beetles, borers, caddisflies, copepods, crane flies, dobsonflies, gnats, leafhoppers, mosquitoes, rotifers, scuds, water fleas and worms nourish common clubtail members of the Gomphidae dragonfly family.

North American cobra clubtail dragonfly habitats offer northward to southward, season-coldest temperatures from minus 45 to 20 degrees Fahrenheit (minus 42.11 to minus 6.66 degrees Celsius).

Beech, bellflower, birch, bladderwort, cattail, daisy, grass, greenbrier, heath, laurel, madder, maple, nettle, olive, pepperbush, pine, pondweed, rush, sedge, water-lily and willow families promote cobra clubtails.

One pointed, tiny tubercle (bump) for each simple side and wide-separated green compound eye; ovipositors; two claspers; and yellow-dominated abdominal sides qualify as adult female hallmarks. Adult males reveal black- or brown-marked green or yellow faces; green- or yellow-marked black or brown thoraxes; green- or yellow-dashed, lined, spotted black or brown abdomens. Adults show off 1.81- to 2.24-inch (46- to 57-millimeter) head-body lengths; 1.29- to 1.65-inch (33- to 42-millimeter) abdomens; and 1.06- to 1.38-inch (27- to 35-millimeter) hindwings.

Big, pale-marked thoraxes and pale-dashed, lined and spotted abdomens with cobra hood-like tips tell cobra clubtails from other odonates in North American cobra clubtail dragonfly habitats.

Two distinctive field markers for the male cobra clubtail dragonfly (Gomphus vastus) are indented hindwings and three terminal appendages; Riverbend Park, Fairfax County, Northern Virginia; May 16, 2016: Walter Sanford @Geodialist, via Twitter May 19, 2016

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Retired science teacher Walter Sanford shares that two distinctive field markers for the female cobra clubtail dragonfly (Gomphus vastus) are rounded hindwings and two terminal appendages known as cerci; Riverbend Park, Fairfax County, Northern Virginia; May 16, 2016: Walter Sanford @Geodialist, via Twitter May 21, 2016, @ https://twitter.com/Geodialist/status/733946337155158016

Two distinctive field markers for the male cobra clubtail dragonfly (Gomphus vastus) are indented hindwings and three terminal appendages; Riverbend Park, Fairfax County, Northern Virginia; May 16, 2016: Walter Sanford @Geodialist, via Twitter May 19, 2016, @ https://twitter.com/Geodialist/status/733221998734671872

For further information:

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Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/1951863
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Available via Internet Archive @ https://archive.org/stream/jstor-4059488/4059488#page/n31/mode/1up

Walter Sanford ‏@Geodialist. "Cobra Clubtail claspers." Twitter. May 19, 2016.
Available @ https://twitter.com/Geodialist/status/733221998734671872

Walter Sanford @Geodialist. "Cobra Clubtail dragonflies (females)." Twitter. May 21, 2016.
Available @ https://twitter.com/Geodialist/status/733946337155158016