Green darner

{{short description|Species of dragonfly}} {{Speciesbox | image = Common Green Darner Anax junius JG.jpg | image_caption = Adult Male, Florida USA | image2 = Anax junius.JPG | image2_caption = Adult female, Blackwell Forest Preserve, Illinois<ref>Cirrus Digital [http://www.cirrusimage.com/dragonfly_green_darner.htm Anax junius] {{Webarchive|url=https://web.archive.org/web/20160303220649/http://www.cirrusimage.com/dragonfly_green_darner.htm |date=2016-03-03 }}</ref> | status = LC | status_system = IUCN3.1 | status_ref = <ref>{{cite iucn|author=Paulson, D.R.|year=2018|title=''Anax junius''|article-number=e.T165081A65831504|doi=10.2305/IUCN.UK.2018-1.RLTS.T165081A65831504.en|access-date=28 July 2023}}</ref> | taxon = Anax junius | authority = (Drury, 1773) | synonyms = *''Libellula junia'' Drury, 1773 *''Anax spiniferus'' Rambur, 1842 *''Anax ocellatus'' Hagen, 1867 *''Anex junius'' (Drury) *''Gomphus junius'' (Drury, 1773) *''Anax severus'' Hagen, 1867 | synonyms_ref = <ref name=biolib>{{cite web|url=https://www.biolib.cz/en/taxon/id225823/|title=Common Green Darner|website=Project BioLib|access-date=28 July 2023|year=2023}}</ref><ref>{{GBIF|taxon=''Anax junius'' Drury, 1773|id=5051741|access-date=28 July 2023}}</ref> }}

The '''green darner''' or '''common green darner'''<ref>{{cite book|last=Dunkle|first=Sidney W.|title=Dragonflies through Binoculars: A Field Guide to Dragonflies of North America|url=https://books.google.com/books?id=MKUmCxZjOCAC|year=2000|publisher=Oxford University Press|isbn=978-0-19-972729-2|page=33}}</ref> ('''''Anax junius'''''), after its resemblance to a darning needle, is a species of dragonfly in the family Aeshnidae. One of the most common and abundant species throughout North America, it also ranges south to Panama.<ref>{{cite book |last= Eaton |first= Eric R. |author2=Kaufman, Kenn |title= Kaufman Field Guide to Insects of North America |publisher= Houghton Mifflin Company |year= 2006 |page= 42 |isbn= 978-0-618-15310-7}}</ref> It is well known for its great migration distance from the northern United States south into Texas and Mexico.<ref>{{cite book |last= Evans |first= Arthur V. |title= Field Guide to Insects and Spiders of North America |year= 2007 |publisher= Sterling Publishing Co., Inc |page=62 |isbn= 978-1-4027-4153-1}}</ref><ref name="HallworthMarra2018">{{cite journal |last1=Hallworth |first1=Michael T. |last2=Marra |first2=Peter P. |last3=McFarland |first3=Kent P. |last4=Zahendra |first4=Sara |last5=Studds |first5=Colin E. |title=Tracking dragons: stable isotopes reveal the annual cycle of a long-distance migratory insect|journal=Biology Letters |volume=14 |issue=12 |year=2018 |article-number=20180741 |doi=10.1098/rsbl.2018.0741|pmid=30958242 |pmc=6303508 }}</ref> It also occurs in the Caribbean, Tahiti, and Asia from Japan to mainland China.<ref name=UMMZ>{{cite web|last=Miner|first=Angela|title=''Anax junius''|website=Animal Diversity Web|year=2014|editor-last=Martina|editor-first=Leila Siciliano|url=https://animaldiversity.org/accounts/Anax_junius/|access-date=28 July 2023}}</ref> It is the official insect for the state of Washington in the United States.<ref>{{Cite web |title=RCW 1.20.047: State insect. |url=https://app.leg.wa.gov/rcw/default.aspx?cite=1.20.047 |access-date=2025-05-31 |website=app.leg.wa.gov}}</ref>

The green darner is a large dragonfly; males grow to {{convert|8|cm|in|abbr=on}} in length with a wingspan up to {{convert|10|cm|in|0|abbr=on}}.<ref name=UMMZ/><ref name="bugguide"/><ref name=":02"/><ref>{{cite book |last= Hahn |first= Jeffrey |title= Insects of the North Woods |year=2009 |publisher= Kollath+Stensaas Publishing |page=16 |isbn= 978-0-9792006-4-9}}</ref>

Females oviposit in aquatic vegetation, eggs laid beneath the water surface. Nymphs (naiads) are aquatic carnivores, feeding on insects, tadpoles, and small fish. Adult darners catch insects on the wing, including ant alates, moths, mosquitoes, and flies.

== Taxonomy == Dru Drury described this species as ''Libellula junius'' in 1773.<ref>{{Cite web|title=World Odonata List · University of Puget Sound|url=https://www2.pugetsound.edu/academics/academic-resources/slater-museum/biodiversity-resources/dragonflies/world-odonata-list/|access-date=2021-11-07|website=www2.pugetsound.edu|archive-date=2021-10-05|archive-url=https://web.archive.org/web/20211005015243/https://www2.pugetsound.edu/academics/academic-resources/slater-museum/biodiversity-resources/dragonflies/world-odonata-list/}}</ref> There are not currently any recognized subspecies. There are three recognized synonyms: ''Anax spiniferus'' Rambur, 1842; ''Anax ocellatus'' Hagen, 1867; ''Anax severus'' Hagen, 1867.<ref name=biolib/>

== Distribution == Common green darners are commonly found throughout the continental United States and southern Canada, occasionally ranging as far south as Panama, particularly in the winter.<ref name=":02"/> There are also populations in Hawaii and the Caribbean. Vagrant individuals have been seen far outside of their normal range including sightings in Alaska, Russia, China, Japan, France, the United Kingdom, India, and Bermuda. These vagrant sightings are likely migrating individuals blown off-course by strong winds or storms.<ref name=UMMZ/>

== Characteristics == Common green darners are large dragonflies, ranging from {{convert|6.8|to|8|cm|in|sp=us}}<ref name="bugguide">{{Cite web|title=Species Anax junius - Common Green Darner|url=https://bugguide.net/node/view/585|access-date=2021-10-26|website=bugguide.net}}</ref> in length and a wingspan of up to {{convert|10|cm|in|0|sp=us}}.<ref name=":02">{{Cite book|last=Paulson|first=Dennis|title=Dragonflies and Damselflies of the East|publisher=Princeton University Press|year=2012|location=Princeton, New Jersey}}</ref> Both sexes have an unmarked green thorax. Mature males have bluish-purple abdomens (the first few abdominal segments are the brightest) with a black dorsal stripe that broadens near the end of the abdomen. Immature males and most females have reddish-brown abdomens, but some females are patterned like adult males. Wings are initially clear but usually become amber-tinted with age, especially in females.<ref name=":02" /><ref name=UMMZ/> Both sexes have a black 'bulls-eye' mark on the face (more precisely, the frons) in front of their eyes, a distinguishing field mark that separates them from the superficially similar comet darner (''Anax longipes'').<ref name=":3">{{Cite web|title=Wisconsin Odonata Survey: Anax junius|url=https://wiatri.net/inventory/odonata/SpeciesAccounts/SpeciesDetail.cfm?TaxaID=16|access-date=2021-10-26|website=wiatri.net}}</ref><ref name=":02" /> This species oviposits in tandem which is a unique behavior among North American darners.<ref name=":3" /><ref name=":02" />

== Natural history == === Diet and predators === Both the adult and the nymphal stage are predators. Nymphs prey upon immature aquatic insects (including their own species), small crustaceans, small tadpoles, and small fish. Adults primarily prey on winged insects, including wasps, flies, butterflies, and other Odonates. The primary predators of common green darner nymphs are fish. Adults are preyed upon by birds and occasionally robber flies, spiders, and other large dragonflies.<ref name=UMMZ/>

=== Habitat === Nymphs develop in lakes, ponds, and slow streams and rivers.<ref name=":02"/> Adults are most frequently seen around nymph habitat but they are strong fliers and can be found in a wide variety of habitats including grasslands, forests, and urban areas.<ref name=UMMZ/>

=== Migration === There are several species of migratory dragonflies in North America, but common green darners are the best studied.<ref name="May 2013">{{Cite journal|last=May|first=Michael L.|date=2013-02-01|title=A critical overview of progress in studies of migration of dragonflies (Odonata: Anisoptera), with emphasis on North America|journal=Journal of Insect Conservation|language=en|volume=17|issue=1|pages=1–15|doi=10.1007/s10841-012-9540-x|s2cid=15916175 |doi-access=free|bibcode=2013JICon..17....1M }}</ref> Other migratory species include:

* ''Tramea lacerata'' (black saddlebags) * ''Pantala flavescens'' (wandering glider) * ''Pantala hymenea'' (spot-winged glider) * ''Sympetrum corruptum'' (variegated meadowhawk)<ref name="May 2013"/>

The large geographic range and migratory behavior of the common green darner has made it a challenge to piece together its complex life history. Recent research has indicated that the annual life cycle of ''Anax junius'' is likely composed of at least three different generations.<ref name="HallworthMarra2018"/> The first generation emerges in the southern end of its range in early spring and migrates northwards through spring and summer. The second generation emerges in the northern end of its range in summer and migrates southwards in fall. The third generation occurs in the south during the winter and does not migrate. Common green darners migrate in fall and spring but for several reasons the southward movement in fall is more noticeable.<ref name="May 2013"/>

By attaching micro-radio transmitters to common green darners, researchers have found them to be capable of migrating up to {{convert|140|km|mi|sp=us}} in a day, though they typically cover less distance per day. A group of researchers used stable isotope analysis on individuals collected between Ontario and Mexico during fall and documented that >90% of individuals moved southward, with an average distance of 900 kilometers.<ref name="May 2013"/>

A study published in 2019 attached miniaturized radio transmitters to common green darners in the Great Lakes region and tracked their movement with the Motus Wildlife Tracking System. Individuals moved at an average groundspeed of {{convert|16|km/h|mph|sp=us}}.<ref>{{Cite journal|last1=Knight|first1=Samantha M.|last2=Pitman|first2=Grace M.|last3=Flockhart|first3=D. T. Tyler|last4=Norris|first4=D. Ryan|date=2019-07-26|title=Radio-tracking reveals how wind and temperature influence the pace of daytime insect migration|journal=Biology Letters|volume=15|issue=7|article-number=20190327 |doi=10.1098/rsbl.2019.0327|pmc=6684972|pmid=31266418}}</ref>

== Gallery == <gallery> File:Img 041538 mating anax junius.jpg|Mating, wheel position File:Anax_junius-Laying_eggs-2.jpg|Egg-laying File:Dragonfly_Common_Green_Darner_Female_Anax_junius_2010-04-18.jpg|Female File:Common Green Darner, female.jpg|Uncommon blue form female, Ottawa, Canada File:Anax junius-hovering.jpg|Hovering San Joaquin Wildlife Sanctuary </gallery>

==References== {{Reflist}}

==External links== {{Commonscat-inline|Anax junius|''Anax junius''}}

Category:Aeshnidae Category:Odonata of Asia Category:Odonata of North America Category:Insects of the Dominican Republic Category:Symbols of Washington (state) Category:Insects described in 1773 Category:Taxa named by Dru Drury