Sunday, January 21, 2018

Fragile Forktail Damselfly Habitats: Exclamation Mark Design on Thorax


Summary: North American fragile forktail damselfly habitats from Canada all the way to Mexico and Guatemala get exclamation mark-patterned thoraxes.


Fragile forktail damselflies (Ischnura posita) display unique thoracic stripes patterned like exclamation points; female fragile forktail damselfly at Kenilworth Aquatic Gardens, Washington DC; Aug. 29, 2015: Judy Gallagher, CC BY 2.0, via Wikimedia Commons

North American fragile forktail damselfly habitats allow arboriculture, master gardening and master naturalism along slow-watered distribution ranges from Newfoundland through Florida inland into Kansas, Minnesota, Nebraska, Oklahoma, Texas and southward through Guatemala.
Pollution-tolerant fragile forktails bear their common name for diminutive sizes and fork-tipped abdomens and the scientific name Ischnura posita (thin tail positive) for exclamation mark-patterned thoraxes. Common names channel the consensus of scientific committees convened by the Dragonfly Society of the Americas, whose Argia journal issues since 1989 can be consulted online. Scientific designations dissect descriptions in 1861 by Hermann August Hagen (May 30, 1817-Nov. 9, 1893), specialist from Königsberg, Prussia, in extant and extinct damselflies and dragonflies.
Fragile forktail damselfly lifespans expect slow-flowing ditches, lakes, marshes, ponds, rivers, streams and swamps with dense, shaded beds of grass, herbaceous vegetation, sedge and woody plants.

January through December function as maximum, most southerly flight seasons even though May through August furnish wildlife mapping opportunities throughout all northern and southern habitat niches.
Female and male fragile forktails grab the same grassy, herbaceous, shrubby branches, stalks and stems for daytime perching at oblique, and night-time roosting at right, angles. They head from hidden, overlapping perches and roosts to open perches in emergent, floating mare's tail, pondweed and water lily beds during cloudy, cool, predator-free days. They incline toward grassy, herbaceous, sedge and shrubby beds even along polluted, slow-moving lakes, marshes, ponds, rivers, springs, streams and swamps and in polluted, shady woodlands.
Ants, assassin flies, biting midges, ducks, falcons, fish, flycatchers, frogs, grebes, lizards, spiders, turtles and water beetles and mites jeopardize North American fragile forktail damselfly habitats.

Immature fragile forktails keep to dull-colored, small-sized forms even though dark-bodied, immature females and brown-bodied tenerals respectively know bright blue and exclamation mark-like, interrupted shoulder stripes.
Incomplete metamorphosis lets fragile forktail damselflies live as eggs in aquatic vegetation, as egg-hatched, multi-molting larvae, naiads or nymphs underwater and as shiny-winged, soft-bodied, weak-flying tenerals. Tenerals quickly mature sexually into adults that mate and make ovipositing a female, not tandem, maneuver into the emergent stems of such floating vegetation as duckweed. Forktail members of the Coenagrionidae pond damsel family need aphids, beetles, borers, caddisflies, copepods, crane flies, dobsonflies, gnats, leafhoppers, mosquitoes, rotifers, scuds, water fleas and worms.
North American fragile forktail damselfly habitats offer season-coldest temperature ranges, northward to southward, from minus 43 to 35-plus degrees Fahrenheit (minus 42.77 to 1.66-plus 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 fragile forktails.
Black abdomens graying with age and dull upper thoraxes with blue, faded, interrupted stripes darkening with age and patterned like exclamation points quicken adult female identifications. Shiny adult males reveal black thoraxes with green interrupted stripes reminiscent of exclamation marks, green eyes and faces, green-segmented black abdomens, small eyespots and yellow-green faces. Adults show off 0.83- to 1.14-inch (21- to 29-millimeter) head-body lengths, 0.63- to 0.87-inch (16- to 22-millimeter) abdomens and 0.39- to 0.63-inch (10- to 16-millimeter) hindwings.
No other forktails transmit black abdomens and thoraxes with interrupted stripes in exclamation mark-like patterns as they transit through overlapping North American fragile forktail damselfly habitats.

Fragile forktail's characteristic exclamation point pattern of thoracic stripes is green for males and blue for females; male fragile forktail dragonfly (Ischnura posita) in Woodbridge, Prince William County, Northern Virginia; April 30, 2011: Judy Gallagher, CC BY 2.0, via Wikimedia Commons

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

Image credits:
Fragile forktail damselflies (Ischnura posita) display unique thoracic stripes patterned like exclamation points; female fragile forktail damselfly at Kenilworth Aquatic Gardens, Washington DC; Aug. 29, 2015: Judy Gallagher, CC BY 2.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Fragile_Forktail_-_Ischnura_posita,_Kenilworth_Aquatic_Gardens,_Washington,_D.C._-_20604912774.jpg?uselang=fr
Fragile forktail's characteristic exclamation point pattern of thoracic stripes is green for males and blue for females; male fragile forktail dragonfly (Ischnura posita) in Woodbridge, Prince William County, Northern Virginia; April 30, 2011: Judy Gallagher, CC BY 2.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Fragile_Forktail_-_Ischnura_posita,_Woodbridge,_Va._-_5678072683.jpg?uselang=fr

For further information:
Abbott, John C. Dragonflies and Damselflies of Texas and the South-Central United States: Texas, Louisiana, Arkansas, Oklahoma and New Mexico. Princeton NJ; Oxford UK: Princeton University Press, 2005.
Beaton, Giff. Dragonflies & Damselflies of Georgia and the Southeast. Athens GA; London UK: University of Georgia Press, 2007.
Berger, Cynthia. Dragonflies. Mechanicsburg PA: Stackpole Books: Wild Guide, 2004.
Bright, Ethan. "Ischnura posita (Hagen, 1861: 77 -- as Agrion) -- Fragile Forktail." Aquatic Insects of Michigan > Odonata (Dragon- and Damselflies) of Michigan > Zygoptera, Selys, 1854 > Coenagrionidae, Kirby, 1890 (Pond Damselflies) > Ischnura Charpentier, 1840 (Forktails).
Available @ http://www.aquaticinsects.org/sp/Odonata/sp_oom.html
Hagen, Hermann. "6. A. positum! Agrion positum Hagen!" Synopsis of the Neuroptera of North America. With a List of the South American Species: 77. Smithsonian Miscellaneous Collections, vol. IV, art. I. Translated from Latin to English by Philip Reese Uhler. Washington DC: Smithsonian Institution, July 1861.
Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/18918180
Available via HathiTrust @ https://hdl.handle.net/2027/aeu.ark:/13960/t32241f34?urlappend=%3Bseq=112
"Ischnura posita." James Cook University-Medusa: The Odonata - Dragonflies and Damselflies > Zygoptera > Coenagrionidae > Ischnura.
Available via James Cook University-Medusa @ https://medusa.jcu.edu.au/Dragonflies/openset/displaySpecies.php?spid=3755
Paulson, Dennis. Dragonflies and Damselflies of the East. Princeton NJ: Princeton University Press, Princeton Field Guides, 2011.


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