Black-Shouldered Spinyleg Dragonfly: Small Head, Long-Spined Long Legs

Summary: North American black-shouldered spinyleg dragonfly habitats get green eyes, small heads, long-spined legs, striped thoraxes and triangle-marked abdomens.

black-shouldered spinyleg dragonfly (Dromogomphus spinosus); Pope County, west central Arkansas; Saturday, June 14, 2008, 12:15:42: Eric Haley, CC BY 2.0 Generic, via Wikimedia Common

North American black-shouldered spinyleg dragonfly habitats abound in gravel-, rock, sand-, water-friendly cultivation and naturalism in distribution ranges from Nova Scotia through Texas, Nebraska, Missouri, Illinois, Wisconsin, Minnesota, Alberta, Ontario and Maine.

Black-shouldered spinylegs bear their common name for dark-striped shoulders and long-spined hind thighs and the scientific name Dromogomphus spinosus (running [crossbow arrow-like] bolt [with] spined [thighs]). Scientific committee consensus in the Dragonfly Society of the Americas, whose 35th Bulletin of American Odonatology checklists Canada's odonates, coordinate common names and scientific committee consensus. Descriptions in 1854 by Michel Edmond de Selys Longchamps (May 25, 1813-Dec. 11, 1900), whose 77-year maintained diary entries were published in 2008, dominate scientific designations.

Black-shouldered spinyleg life cycles expect clean or degraded, slow- to swift-flowing lakes, oxbows, ponds, rivers and streams with gravelly margins and muddy, rocky or sandy bottoms.

April through November function as earliest to latest flight seasons even though June through August furnish wildlife mapping opportunities throughout black-shouldered spinyleg coastal and inland niches.

Black-shouldered spinylegs always gaze toward water whenever they go out mid-mornings for mates, perches and prey on pool, riffle or shore rocks, soil and woody vegetation. They hold their abdomens above their heads when hovering 3 feet (0.91 meter) above currents and toward the midday sun when obelisking for body temperature control. Their sallier percher itineraries involve fast, irregular, large, racetrack-like, smooth, wide patrols through dense forest cover, slow landings with legs extended and shady forest edge perches.

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

Immature, wedge-shaped black-shouldered spinylegs keep gravelly, muddy, rocky and sandy water bottom- and waterside sediment-kind yellow colors even though adults know green eyes and black-and-yellow bodies.

Incomplete metamorphosis links round eggs loosened regularly from female abdomens into 2- to 3-foot (0.61- to 0.91-meter) stretches of water, larvae, naiads or nymphs and tenerals. Acidic water-intolerant, pollution-tolerant, multi-molting, nonflying larvae metamorphose into shiny-winged, tender-bodied, weak-flying tenerals that mature, mate above and amid the treetops 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 black-shouldered spinyleg dragonfly habitats offer northward to southward, season-coldest temperatures from minus 45 to 25 degrees Fahrenheit (minus 42.11 to minus 3.88 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 black-shouldered spinylegs.

Small yellow heads; black crowns; green foreheads; barely clubbed, egg-thickened abdomens; egg-filled ovipositors; two black spines; two claspers qualify as adult female black-shouldered spinyleg dragonfly hallmarks. Dainty-headed, green-eyed, yellow-faced adult males reveal black-striped green-yellow thoraxes; long legs with long-spined hind thighs; dusky-edged wings; clubbed, slender, yellow-lined, yellow triangle-patterned abdomens; and three claspers. Adults show off 2.12- to 2.64-inch (54- to 67-millimeter) head-body lengths, 1.65- to 1.77-inch (42- to 45-millimeter) abdomens and 1.34- to 1.42-inch (34- to 36-millimeter) hindwings.

Black-striped green-yellow thoraxes, dusky-edged wings, long-spined long legs, slender yellow triangle-marked abdomens tell dainty-headed black-shouldered spinylegs from other odonates in North American black-shouldered spinyleg dragonfly habitats.

female black-shouldered spinyleg dragonfly (Dromogomphus spinosus); Potomac River at Riverbend Park, Fairfax County, Northern Virginia: Walter Sanford @Geodialist, via Twitter Aug. 17, 2016

Acknowledgment

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

Image credits:

black-shouldered spinyleg dragonfly (Dromogomphus spinosus); Pope County, west central Arkansas; Saturday, June 14, 2008, 12:15:42: Eric Haley, CC BY 2.0 Generic, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Dromogomphus_spinosus.jpg; pondhawk, CC BY 2.0 Generic, via Flickr @ https://www.flickr.com/photos/38686613@N08/4747914782

female black-shouldered spinyleg dragonfly (Dromogomphus spinosus); Potomac River at Riverbend Park, Fairfax County, Northern Virginia: Walter Sanford @Geodialist, via Twitter Aug. 17, 2016, @ https://twitter.com/Geodialist/status/765835907115003904

For further information:

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Berger, Cynthia. Dragonflies. Mechanicsburg PA: Stackpole Books: Wild Guide, 2004.

Bright, Ethan. "Dromogomphus spinosus Selys, 1854: 21 - Black-shouldered Spinyleg." Aquatic Insects of Michigan > Odonata (Dragon- and Damselflies) of Michigan > Anisoptera Selys, 1854 - Dragonflies > Gomphidae (Clubtails) > Dromogomphus Selys, 1854 (Spinylegs).
Available @ http://www.aquaticinsects.org/sp/Odonata/sp_oom.html

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Available via James Cook University-Medusa @ https://medusa.jcu.edu.au/Dragonflies/openset/displaySpecies.php?spid=1128

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Available @ https://www.odonatacentral.org/docs/NA_Odonata_Checklist.pdf

Sélys-Longchamps, M.Edm. (Michel Edmond) de. "Synopsis des Gomphines: 51. Dromogomphus spinosus, De Selys." Bulletins de l'Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique, tome XXI (Série 1), IIme partie, no. 7: 59. Bruxelles (Brussels), Belgium: M. Hayez, 1854
Available via Biodiversity Heritage Library @ http://biodiversitylibrary.org/page/39438411
Available via HathiTrust @ https://hdl.handle.net/2027/uiug.30112112254658?urlappend=%3Bseq=71

"The 2012 USDA Plant Hardiness Zone Map." The National Gardening Association > Gardening Tools > Learning Library USDA Hardiness Zone > USDA Plant Hardiness Zone Map.
Available @ https://garden.org/nga/zipzone/2012/

Walter Sanford @Geodialist. "More Black-shouldered Spinyleg dragonflies." Twitter. Aug. 17, 2016.
Available @ https://twitter.com/Geodialist/status/765835907115003904