Editing Mecoptera

{{short description|Order of insects with markedly different larvae and adults}}
{{good article}}
{{Automatic taxobox
| fossil_range = {{fossilrange|299|0|[[Permian|Early Permian]] - Recent}}
| image = Skorpionsfliege Panorpa communis male full (cropped).jpg
| image_caption = ''[[Panorpa communis]]'', male
| taxon = Mecoptera
| authority = [[Alpheus Spring Packard|Packard]], 1886<br>[[John Henry Comstock|Comstock]], 1895
| subdivision_ranks = Families
| subdivision = 
* [[Apteropanorpidae]]
* [[Boreidae]] (snow scorpionflies)
* [[Choristidae]]
* †[[Choristopsychidae]]<ref name="Qiao2013">{{cite journal |last1=Qiao |first1=X. |last2=Shih |first2=C. K. |last3=Petrulevičius |first3=J. F. |last4=Dong |first4=R. |year=2013 |title=Fossils from the Middle Jurassic of China shed light on morphology of Choristopsychidae (Insecta, Mecoptera) |journal=ZooKeys |issue=318 |pages=91–111 |doi=10.3897/zookeys.318.5226|pmid=23950679 |pmc=3744206 |doi-access=free |bibcode=2013ZooK..318...91Q }}</ref>
* †[[Englathaumatidae]]<ref name="Novokshonov2016">{{cite journal |last1=Novokshonov |first1=V. G. |last2=Ross |first2=A. J. |last3=Cook |first3=E. |last4=Krzemiński, W. |last5=Soszyńska-Maj |first5=A. |year=2016 |title=A new family of scorpionflies (Insecta; Mecoptera) from the Lower Cretaceous of England |journal=Cretaceous Research |volume=62 |pages=44–51 |doi=10.1016/j.cretres.2016.01.013|bibcode=2016CrRes..62...44N }}</ref>
* [[Eomeropidae]]
* [[Meropeidae]] (earwigflies)
*†[[Permochoristidae]]<ref name="Bashkuev2011"/>
*†Mesopsychoidea (=Aneuretopsychina)
**†[[Aneuretopsychidae]]<ref name="Bashkuev2011"/>
**†[[Mesopsychidae]]<ref name="Lin2016">{{cite journal |last1=Lin |first1=X. |last2=Shih |first2=M. J. |last3=Labandeira |first3=C. C. |last4=Ren |first4=D. |year=2016 |title=New data from the Middle Jurassic of China shed light on the phylogeny and origin of the proboscis in the Mesopsychidae (Insecta: Mecoptera) |journal=BMC Evolutionary Biology |volume=16 |issue=1 |pages=1–22 |doi=10.1186/s12862-015-0575-y|pmid=26727998 |pmc=4700641 |doi-access=free |bibcode=2016BMCEE..16....1L }}</ref>
**†[[Nedubroviidae]]<ref name="Bashkuev2011">{{cite journal |last1=Bashkuev |first1=A.S. |s2cid=83075922 |year=2011 |title=Nedubroviidae, a new family of Mecoptera: the first Paleozoic long-proboscid scorpionflies |journal=Zootaxa |volume=2895 |issue=1 |pages=47–57 |doi=10.11646/zootaxa.2895.1.3}}</ref>
**†[[Pseudopolycentropodidae]]<ref name="Grimaldi2014">{{cite journal |last1=Grimaldi |first1=D. |last2=Johnston |first2=M. A. |year=2014 |title=The long-tongued Cretaceous scorpionfly ''Parapolycentropus'' Grimaldi and Rasnitsyn (Mecoptera: Pseudopolycentropodidae): new data and interpretations |journal=American Museum Novitates |issue=3793 |pages=1–24 |doi=10.1206/3793.1|hdl=2246/6466 |s2cid=54799375 |url=https://www.biodiversitylibrary.org/item/273012 }}</ref>
* [[Nannochoristidae]]
* [[Siphonaptera]]? (fleas)
* [[Pistillifera]]
** [[Panorpoidea]]
***†[[Australochoristidae]]<ref name="Krzemiński2015">{{cite journal |last1=Krzemiński |first1=W. |last2=Soszyńska-Maj |first2=A. |last3=Bashkuev |first3=A. S. |last4=Kopeć |first4=K |year=2015 |title=Revision of the unique Early Cretaceous Mecoptera from Koonwarra (Australia) with description of a new genus and family |journal=Cretaceous Research |volume=52 |pages=501–506 |doi=10.1016/j.cretres.2014.04.004|bibcode=2015CrRes..52..501K }}</ref>
***†[[Austropanorpidae]]
***†[[Cantabridae]]
***†[[Dinopanorpidae]]<ref name="Dinopanorpidae">{{cite journal |author=Archibald, S.B. |s2cid= 55513480 |title= New Dinopanorpida (Insecta: Mecoptera) from the Eocene Okanogan Highlands (British Columbia, Canada and Washington State, USA) |year=2005| journal = [[Canadian Journal of Earth Sciences]] |volume = 42 | issue = 2| pages =119–136 |doi= 10.1139/e04-073|bibcode= 2005CaJES..42..119A }}</ref>
***†[[Eorpidae]]
***†[[Holcorpidae]]
***†[[Orthophlebiidae]]
***[[Panorpidae]] (common scorpionflies)
***[[Panorpodidae]] (short-faced scorpionflies)
***†[[Protorthophlebiidae]]
***†[[Worcestobiidae]]
**[[Raptipedia]]
***[[Bittacidae]] (hangingflies)
***†[[Cimbrophlebiidae]]<ref name="Wang2014">{{cite journal |last1=Wang |first1=C. |last2=Shih |first2=C. |last3=Ren |first3=D |year=2014 |title=A new fossil hangingfly (Mecoptera: Cimbrophlebiidae) from the Early Cretaceous of China |journal=Acta Geologica Sinica (English Edition) |volume=88 |issue=1 |pages=29–34 |doi=10.1111/1755-6724.12180|bibcode=2014AcGlS..88...29W |s2cid=129796533 }}</ref>
}}

'''Mecoptera''' (from the [[Greek language|Greek]]: ''mecos'' = "long", ''ptera'' = "wings") is an [[Order (biology)|order]] of [[insect]]s in the superorder [[Holometabola]] with about six hundred species in nine [[Family (biology)|families]] worldwide. Mecopterans are sometimes called '''scorpionflies''' after their largest family, [[Panorpidae]], in which the males have enlarged genitals raised over the body that look similar to the stingers of [[scorpion]]s, and long beaklike [[Rostrum (anatomy)|rostra]]. The [[Bittacidae]], or hangingflies, are another prominent family and are known for their elaborate mating rituals, in which females choose mates based on the quality of gift prey offered to them by the males. A smaller group is the snow scorpionflies, family [[Boreidae]], adults of which are sometimes seen walking on snowfields. In contrast, the majority of species in the order inhabit moist environments in tropical locations.

The Mecoptera are closely related to the [[Siphonaptera]] (fleas), and a little more distantly to the [[Diptera]] (true flies). They are somewhat fly-like in appearance, being small to medium-sized insects with long slender bodies and narrow membranous wings. Most breed in moist environments such as [[leaf litter]] or moss, and the eggs may not hatch until the wet season arrives. The larvae are caterpillar-like and mostly feed on vegetable matter, and the non-feeding pupae may pass through a diapause until weather conditions are favorable.

Early Mecoptera may have played an important role in [[pollinating]] extinct species of [[gymnosperm]]s before the evolution of other insect pollinators such as bees. Adults of modern species  are overwhelmingly predators or consumers of dead organisms. In a few areas, some species are the first insects to arrive at a [[cadaver]], making them useful in [[forensic entomology]].<ref name=STAFS>{{cite web |title=Southeast Texas Applied Forensic Science Facility |url=http://www.shsu.edu/~stafs/ |publisher=STAFS}}</ref>

==Diversity==

Mecopterans vary in length from {{convert|2|to|35|mm|in|1|abbr=on}}. There are about six hundred [[Neontology|extant]] species known, divided into thirty-four [[genera]] in nine families. The majority of the species are contained in the families [[Panorpidae]] and [[Bittacidae]]. Besides this there are about four hundred known fossil species in about eighty-seven genera, which are more diverse than the living members of the order.<ref name=Dunford>{{cite book|author1=Dunford, James C. |author2=Somma, Louis A. |editor=Capinera, John L. |title=Encyclopedia of Entomology: Scorpionflies (Mecoptera) |url=https://books.google.com/books?id=i9ITMiiohVQC&pg=PA3304 |year=2008 |publisher=Springer Science & Business Media|isbn=978-1-4020-6242-1 |pages=3304–3309}}</ref> The group is sometimes called the scorpionflies, from the turned-up "tail" of the male's genitalia in the Panorpidae.<ref>{{cite web |title=Scorpionflies (Order: Mecoptera) |publisher=Amateur Entomologists' Society |url=https://www.amentsoc.org/insects/fact-files/orders/mecoptera.html |access-date=5 July 2020}}</ref>

Distribution of mecopterans is worldwide; the greatest diversity at the species level is in the [[Afrotropic]] and [[Palearctic realm]]s, but there is greater diversity at the generic and family level in the [[Neotropic]], [[Nearctic]] and [[Australasian realm]]s. They are absent from Madagascar and many islands and island groups; this may demonstrate that their [[Biological dispersal|dispersal]] ability is low, with Trinidad, Taiwan and Japan, where they are found, having had recent land bridges to the nearest continental land masses.<ref name=Dunford/>

==Evolution and phylogeny==

===Taxonomic history===
The European scorpionfly was named ''[[Panorpa communis]]'' by [[Linnaeus]] in [[10th edition of Systema Naturae|1758]].<ref>[[Linnæus]], Carolus.  1758. ''[[Systema naturae]] per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis''. Laurentii Salvii, Holmiae [= Stockholm].  Vol. Tomus I,  Editio decima, reformata: i–ii, 1–824.</ref>
The Mecoptera were named by [[Alpheus Hyatt]] and [[Jennie Maria Arms Sheldon|Jennie Maria Arms]] in 1891.<ref name="HyattArms1891">{{cite journal |last1=Hyatt |first1=Alpheus |last2=Arms |first2=Jennie Maria |title=A novel diagrammatic representation of the orders of insects |journal=Psyche: A Journal of Entomology |date=1891 |volume=6 |issue=177 |pages=11–13 |doi=10.1155/1891/39454|doi-access=free }}</ref> The name is from the [[Greek language|Greek]], ''mecos'' meaning long, and ''ptera'' meaning wings.<ref>{{Cite book|title=A Dictionary of Entomology|journal=Nature|volume=91|issue=2267|url=https://books.google.com/books?id=9IcmCeAjp6cC&pg=PA858|year=2011|isbn=978-1-84593-542-9|page=858|bibcode=1913Natur..91S.134.|doi=10.1038/091134c0|s2cid=3947767}}</ref>
The families of Mecoptera are well accepted by taxonomists but their relationships have been debated. In 1987, R. Willman treated the Mecoptera as a [[clade]], containing the Boreidae as sister to the Meropeidae,<ref>{{cite journal |author=Willman, R. |date=1987 |title=The phylogenetic system of the Mecoptera |journal=Systematic Entomology |volume=12 |issue=4 |pages=519–524 |doi=10.1111/j.1365-3113.1987.tb00222.x|bibcode=1987SysEn..12..519W |s2cid=86349146 }}</ref> but in 2002 [[Michael F. Whiting]] declared the Mecoptera so-defined as paraphyletic, with the Boreidae as sister to another order, the [[Siphonaptera]] (fleas).<ref name=Whiting2002/>

===Fossil history===

Among the earliest members of the Mecoptera are the [[Nannochoristidae]] of [[Upper Permian]] age. Fossil Mecoptera become abundant and diverse during the [[Cretaceous]], for example in China,<ref name="MartillBechly2007">{{cite book |last1=Martill|first1=David M. |last2=Bechly |first2=Günter |last3=Loveridge |first3=Robert F. |title=The Crato Fossil Beds of Brazil: Window into an Ancient World |url=https://books.google.com/books?id=5ZBh_-QvX2MC&pg=PA367 |year=2007 |publisher=Cambridge University Press |isbn=978-1-139-46776-6 |pages=367–369}}</ref> where panorpids such as ''Jurassipanorpa'', hangingflies (Bittacidae and Cimbrophlebiidae), Orthophlebiidae, and Cimbrophlebiidae have been found.<ref>{{cite journal|last1=Wang |first1=Chen |last2=Shih |first2=Chungkun|last3=Ren|first3=Dong |title=A New Fossil Hangingfly (Mecoptera: Cimbrophlebiidae) from the Early Cretaceous of China |journal=Acta Geologica Sinica - English Edition |date=2014 |volume=88 |issue=1 |pages=29–34 |doi=10.1111/1755-6724.12180|bibcode=2014AcGlS..88...29W |s2cid=129796533 }}</ref><ref>{{cite journal |last1=Ding |first1=He|last2=Shih |first2=Chungkun |last3=Bashkuev |first3=Alexei |last4=Zhao |first4=Yunyun |last5=Ren |first5=Dong |title=The earliest fossil record of Panorpidae (Mecoptera) from the Middle Jurassic of China |journal=ZooKeys |date=2014 |issue=431|pages=79–92 |doi=10.3897/zookeys.431.7561|pmid=25152669|pmc=4141175|doi-access=free|bibcode=2014ZooK..431...79D }}</ref>

Extinct Mecoptera species may have been important pollinators of early [[gymnosperm]] seed plants during the late [[Middle Jurassic]] to mid–[[Early Cretaceous]] periods before other pollinating groups such as the bees evolved. These were mainly wind-pollinated plants, but fossil mecopterans had siphon-feeding apparatus that could have fertilized these early gymnosperms by feeding on their [[nectar]] and [[pollen]]. The lack of iron enrichment in their fossilized [[probosces]] rules out their use for drinking blood. Eleven species have been identified from three families, [[Mesopsychidae]], [[Aneuretopsychidae]], and [[Pseudopolycentropodidae]] within the clade [[Aneuretopsychina]]. Their lengths range from {{convert|3|mm|in|abbr=on}} in ''Parapolycentropus burmiticus'' to {{convert|28|mm|in|abbr=on}} in ''Lichnomesopsyche gloriae''. The proboscis could be as long as {{convert|10|mm|in|abbr=on}}. It has been suggested that these mecopterans transferred pollen on their mouthparts and head surfaces, as do [[bee flies]] and [[hoverflies]] today, but no such associated pollen has been found, even when the insects were finely preserved in [[Eocene]] [[Baltic amber]]. They likely pollinated plants such as [[Caytoniaceae]], [[Cheirolepidiaceae]], and [[Gnetales]], which have ovulate organs that are either poorly suited for wind pollination or have structures that could support long-proboscid fluid feeding.<ref name="Ollerton">{{cite journal | last1 = Ollerton | first1 = J. | last2 = Coulthard | first2 = E. | year = 2009 | title = Evolution of Animal Pollination | journal = Science | volume = 326 | issue = 5954| pages = 808–809 | doi = 10.1126/science.1181154 | pmid = 19892970 | bibcode = 2009Sci...326..808O | s2cid = 856038 }}</ref><ref name="Ren">{{cite journal | last1 = Ren | first1 = D. | last2 = Labandeira | first2 = C.C. | last3 = Santiago-Blay | first3 = J.A. | last4 = Rasnitsyn | first4 = A. | last5 = Shih | first5 = C.K. | last6 = Bashkuev | first6 = A. | last7 = Logan | first7 = M.A. | last8 = Hotton | first8 = C.L. | last9 = Dilcher | first9 = D. | year = 2009 | title = Probable Pollination Mode Before Angiosperms: Eurasian, Long-Proboscid Scorpionflies | journal = Science | volume = 326 | issue = 5954| pages = 840–847 | doi = 10.1126/science.1178338 | pmid = 19892981 | pmc = 2944650 | bibcode = 2009Sci...326..840R }}</ref>  The Aneuretopsychina were the most diverse group of mecopterans in the Latest Permian, taking the place of the [[Permochoristidae]], to the [[Middle Triassic]].  During the [[Late Triassic]] through the [[Middle Jurassic]], Aneuretopsychina species were gradually replaced by species from the [[Parachoristidae]] and Orthophlebiidae.  Modern mecopteran families are derived from the Orthophlebiidae.<ref name="Bashkuev2011b">{{Cite book |last1=Bashkuev |first1=A. S. |year=2011 |chapter=The earliest Mesopsychidae and revision of the family Mesopanorpodidae (Mecoptera)|title=Advances in the Systematics of Fossil and Modern Insects: Honouring Alexandr Rasnitsyn |series=ZooKeys 130 |pages=263–279|isbn=978-954-642-609-3 |doi=10.3897/zookeys.130.1611|pmid=22259282 |pmc=3260765 |doi-access=free|publisher=PenSoft|editor-last1=Shcherbakov|editor-first1=D.|editor-last2=Engel|editor-first2=M.|editor-last3=Sharkey|editor-first3=M.}}</ref>

<gallery mode="nolines">
File:Juracimbrophlebia ginkgofolia.jpg|''[[Juracimbrophlebia ginkgofolia]]'' ([[Cimbrophlebiidae]]) reconstruction, Jurassic; China
File:Jurassipanorpa sticta holotype.jpg|''[[Jurassipanorpa|Jurassipanorpa sticta]]'' ([[Panorpidae]]), Jurassic; China
File:Dinokanaga andersoni holotype SR 01-06-01.jpg|Forewing of ''[[Dinokanaga andersoni]]'' ([[Dinopanorpidae]]), [[Eocene]]; Washington state <!--File:Cimbrophlebia brooksi Holotype SR 06-20-05 B.jpg|''[[Cimbrophlebia|Cimbrophlebia brooksi]]'' ([[Cimbrophlebiidae]]), Eocene; Washington state--> <!--File:Eorpa elverumi SRUI 08-07-07 A Holotype.JPG|Forewing of ''[[Eorpa elverumi]]'' ([[Eorpidae]]), Eocene; Washington State--> 
</gallery>

===External relationships===
Mecoptera have special importance in the evolution of the insects. Two of the most important insect orders, [[Lepidoptera]] (butterflies and moths) and [[Diptera]] (true flies), along with [[Trichoptera]] (caddisflies), probably evolved from ancestors belonging to, or strictly related to, the Mecoptera. Evidence includes anatomical and biochemical similarities as well as [[transitional fossil]]s, such as ''[[Permotanyderus]]'' and ''[[Choristotanyderus]]'', which lie between the Mecoptera and Diptera. The group was once much more widespread and diverse than it is now, with four suborders during the [[Mesozoic]].<ref name=IIBD/>

It is unclear as of 2020 whether the Mecoptera form a single clade, or whether the [[Siphonaptera]] (fleas) are inside that clade, so that the traditional "Mecoptera" taxon is paraphyletic. However the earlier suggestion that the Siphonaptera are sister to the [[Boreidae]]<ref name=Whiting2008>{{cite journal |last1=Whiting |first1=Michael F. |author1-link=Michael F. Whiting|last2=Whiting |first2=Alison S. |last3=Hastriter |first3=Michael W. |last4=Dittmar |first4=Katharina |title=A molecular phylogeny of fleas (Insecta: Siphonaptera): origins and host associations |journal=Cladistics |date=2008 |volume=24 |issue=5 |pages=677–707 |doi=10.1111/j.1096-0031.2008.00211.x |citeseerx=10.1.1.731.5211  |s2cid=33808144 }}</ref><ref name=Whiting2002>{{cite journal |last1=Whiting |first1=Michael F. |author1-link=Michael F. Whiting|year=2002 |title=Mecoptera is paraphyletic: multiple genes and phylogeny of Mecoptera and Siphonaptera |journal=Zoologica Scripta |volume=31 |issue=1 |pages=93–104 |url=http://www3.interscience.wiley.com/journal/118916123/abstract |archive-url=https://archive.today/20130105095659/http://www3.interscience.wiley.com/journal/118916123/abstract |url-status=dead |archive-date=2013-01-05 |doi=10.1046/j.0300-3256.2001.00095.x |s2cid=56100681 |url-access=subscription }}</ref><ref name=WiegmannYates2012>{{cite book |last1=Wiegmann |first1=Brian |last2=Yeates |first2=David K. |title=The Evolutionary Biology of Flies |url=https://books.google.com/books?id=rElP5sNn6IYC&pg=PA5 |year=2012 |publisher=Columbia University Press |isbn=978-0-231-50170-5 |page=5 |quote=Recently, a close affinity between Siphonaptera and Mecoptera has been convincingly demonstrated via morphology (Bilinski et al. 1998) and molecular data (Whiting 2002), rendering Mecoptera paraphyletic, but making the clade including Mecoptera and Siphonaptera monophyletic}}</ref> is not supported; instead, there is the possibility that they are sister to another Mecopteran family, the [[Nannochoristidae]]. The two possible trees are shown below:<ref name="Meusemann Trautwein 2020">{{cite bioRxiv |last1=Meusemann |first1=Karen |last2=Trautwein |first2=Michelle |last3=Friedrich |first3=Frank |last4=Beutel |first4=Rolf G. |last5=Wiegmann |first5=Brian M. |last6=Donath |first6=Alexander |last7=Podsiadlowski |first7=Lars |last8=Petersen |first8=Malte |last9=Niehuis |first9=Oliver |last10=Mayer |first10=Christoph |last11=Bayless |first11=Keith M. |last12=Shin |first12=Seunggwan |last13=Liu |first13=Shanlin |last14=Hlinka |first14=Ondrej |last15=Minh |first15=Bui Quang |last16=Kozlov |first16=Alexey |last17=Morel |first17=Benoit |last18=Peters |first18=Ralph S. |last19=Bartel |first19=Daniela |last20=Grove |first20=Simon |last21=Zhou |first21=Xin |last22=Misof |first22=Bernhard |last23=Yeates |first23=David K. |display-authors=5|title=Are Fleas Highly Modified Mecoptera? Phylogenomic Resolution of Antliophora (Insecta: Holometabola) |year=2020 |biorxiv=10.1101/2020.11.19.390666}}</ref>

(a) Mecoptera (clades in boldface) is paraphyletic, containing Siphonaptera:<ref name="Meusemann Trautwein 2020"/><ref name="Tihelka Giacomelli 2020">{{cite journal |last1=Tihelka |first1=Erik |last2=Giacomelli |first2=Mattia |last3=Huang |first3=Di-Ying |last4=Pisani |first4=Davide |last5=Donoghue |first5=Philip C. J. |last6=Cai |first6=Chen-Yang |title=Fleas are parasitic scorpionflies |journal=Palaeoentomology |volume=3 |issue=6 |year=2020 |pages=641–653 |issn=2624-2834 |doi=10.11646/palaeoentomology.3.6.16|doi-access=free |hdl=1983/8d3c12c6-529c-4754-b59d-3abf88a32fc9 |hdl-access=free }}</ref>

{{clade
|label1=[[Antliophora]]
|1={{clade 
   |1=[[Diptera]] (true flies) [[File:Common house fly, Musca domestica.jpg|70px]] 
   |grouplabel2={{clade labels|label1=<span style="color:red;padding:1em;">Mecoptera</span> |top1=38%}}
   |2={{clade
       |1='''[[Pistillifera]]''' (scorpionflies, hangingflies, 400 [[Species|spp]].) [[File:Gunzesrieder Tal Insekt 3.jpg|90px]] |bar1=red
       |2={{clade
          |2={{clade
             |1='''[[Nannochoristidae]]''' (southern scorpionflies, 8 spp.)[[File:Nannochorista philpotti (cropped).jpg|85px]]&nbsp;  |bar1=red
             |2=[[Siphonaptera]] (fleas, 2500 spp.) [[File:British Entomologycutted Plate114.png|50px]]
             }}
          |1='''[[Boreidae]]''' (snow scorpionflies, 30 spp.) [[File:Boreus hiemalis2 detail.jpg|85px]]  |bar1=red
          }}
      }}
   }}
}}

(b) Mecoptera is monophyletic, sister to Siphonaptera:<ref name="Meusemann Trautwein 2020"/>

{{clade
|label1=[[Antliophora]]
|1={{clade 
   |1=[[Diptera]] (true flies) [[File:Common house fly, Musca domestica.jpg|70px]] 
   |2={{clade
       |label1='''Mecoptera'''
       |1={{clade
          |1={{clade
             |1=[[Pistillifera]] (scorpionflies, hangingflies, 400 [[Species|spp]].) [[File:Gunzesrieder Tal Insekt 3.jpg|90px]]
             |2=[[Boreidae]] (snow scorpionflies, 30 spp.) [[File:Boreus hiemalis2 detail.jpg|85px]]
             }}
          |2=[[Nannochoristidae]] (southern scorpionflies, 8 spp.)[[File:Nannochorista philpotti (cropped).jpg|85px]]
          }}
       |label2=[[Siphonaptera]] 
       |2= (fleas, 2500 spp.) [[File:Pulex irritans female ZSM.jpg|50px]]
      }}
   }}
}}

===Internal relationships===
All the families were formerly treated as part of a single order, Mecoptera. The relationships between the families are, however, a matter of debate. The cladogram, from Cracraft and Donoghue 2004, places the Nannochoristidae as a separate order, with the Boreidae, as the sister group to the Siphonaptera, also as its own order. The [[Eomeropidae]] is suggested to be the sister group to the rest of the Mecoptera, with the position of the [[Bittacidae]] unclear. Of those other families, the [[Meropeidae]] is the most basal, and the relationships of the rest are not completely clear.<ref>{{cite book |last=Whiting |first=Michael F. |chapter=Phylogeny of the Holometabolous Insects |editor-last1=Cracraft|editor-first1=Joel|editor-last2=Donoghue|editor-first2=Michael J.|title=Assembling the Tree of Life|chapter-url=https://books.google.com/books?id=6lXTP0YU6_kC&pg=PA355|year=2004|publisher=Oxford University Press|isbn=978-0-19-972960-9|page=355}}</ref>
{{clade
|1={{clade
   |label1='''Nannomecoptera'''
   |1={{clade 
      |1=[[Nannochoristidae]]{{efn|name=Nannomecoptera|Some studies find Nannomecoptera as sister to the Boreidae+Siphonaptera clade.<ref name=Whiting2002/>}}
      }}
   |2={{clade
      |1={{clade
         |label1='''Neomecoptera'''
         |1={{clade
            |1=[[Boreidae]] (snow scorpionflies) [[File:Boreus hyemalis male.jpg|90px]]
            }}
         |2='''[[Siphonaptera]]''' (fleas) [[File:Pulex irritans female ZSM.jpg|65px]] 
         }}      
      |2={{clade
         |label1='''Mecoptera''' |sublabel1= ''sensu stricto''
         |1={{clade
            |1=[[Eomeropidae]] (mainly fossil ([[Triassic]] to present), 1 extant sp.) [[File:Notiothauma reedi.jpg|90px]]
            |2=(?) [[Bittacidae]]{{efn|name=Bittacidae}} (hangingflies) |state2=dotted
            |3={{clade
               |1=[[Meropeidae]] (earwigflies) [[File:Merope tuber dorsal view - ZooKeys-269-051-g007A.jpeg|90px]]  
               |2={{clade
                  |1=[[Choristidae]] (Australian scorpionflies) [[File:Chorista australis Gundaroo NSW Australia.jpg|90px]] 
                  |2=[[Apteropanorpidae]] (Tasmanian snow scorpionflies)
                  |3={{clade
                     |1={{clade
                        |1=(?)[[Bittacidae]]{{efn|name=Bittacidae}} (hangingflies) [[File:Hylobittacus apicalis Michigan.jpg|90px]] |state2=dotted|state1=dotted
                        |2=[[Panorpodidae]] (short-faced scorpionflies)
                        }}
                     |2=[[Panorpidae]] ([[Jurassic]] to present,  common scorpionflies) [[File:Panorpa communis V.jpg|70px]]
                     }}
                  }}
               }}
            }}
         }}
      }}  
   }}
}}
{{notelist|refs=
{{efn |name=Bittacidae|The position of the [[Bittacidae]] is unclear. Two alternative positions, either basal within Mecoptera ''sensu stricto'' or sister to Panorpodidae, are shown.}}
}}
[[File:Panorpa dubia (Mecoptera) anatomy.tiff|thumb|250px|Male ''[[Panorpa|Panorpa dubia]]''.<br/> A, Body in lateral view; B–D. male genital bulb and gonostyli. B, dorsal view; C, ventral view; D, lateral view. ep, epandrium; gcx, gonocoxite; gs, gonostylus; hv, hypovalva; hyp, hypandrium. Scale bars represent 3 mm in A, 1 mm in B–D]]

==Biology==
===Morphology===

Mecoptera are small to medium-sized insects with long beaklike [[Rostrum (anatomy)|rostra]], membranous wings and slender, elongated bodies. They have relatively simple mouthparts, with a long [[Insect mouthparts#Labium|labium]], long [[Mandible (arthropod mouthpart)|mandible]]s and fleshy [[palp]]s, which resemble those of the more primitive [[true flies]]. Like many other insects, they possess [[compound eye]]s on the sides of their heads, and three [[ocelli]] on the top. The antennae are filiform (thread-shaped) and contain multiple segments.<ref name=IIBD>{{cite book |author1=Hoell, H.V. |author2=Doyen, J.T. |author3=Purcell, A.H. |year=1998 |title=Introduction to Insect Biology and Diversity, 2nd ed |publisher= Oxford University Press |pages= 488–491|isbn= 978-0-19-510033-4}}</ref><ref name="GullanCranston2014">{{cite book|author1=Gullan, P.J.|author2=Cranston, P.S.|title=The Insects: An Outline of Entomology|url=https://books.google.com/books?id=lF5hBAAAQBAJ&pg=PT1345|year=2014 |publisher=Wiley |isbn=978-1-118-84616-2 |pages=1345–1347}}</ref>

The fore and hind wings are similar in shape, being long and narrow, with numerous cross-veins, and somewhat resembling those of primitive insects such as [[mayflies]]. A few genera, however, have reduced wings, or have lost them altogether. The [[Insect morphology#Abdomen|abdomen]] is cylindrical with eleven segments, the first of which is fused to the [[metathorax]]. The [[Cercus|cerci]] consist of one or two segments. The abdomen typically curves upwards in the male, superficially resembling the tail of a [[scorpion]], the tip containing an enlarged structure called the genital bulb.<ref name=IIBD/><ref name="GullanCranston2014"/>

The [[caterpillar]]-like [[larva]]e have hard [[sclerotised]] heads with mandibles (jaws), short true legs on the thorax, [[proleg]]s on the first eight abdominal segments, and a suction disc or pair of hooks on the terminal tenth segment. The pupae have free appendages rather than being secured within a cocoon (they are exarate).<ref name="GullanCranston2014"/>

===Ecology===
[[File:Panorpa communis with prey Diogma glabrata glabrata.jpg|thumb|A [[Panorpidae|Panorpid]] scorpionfly feeding on a dead insect]]

Mecopterans mostly inhabit moist environments although a few species are found in semi-desert habitats. Scorpionflies, family Panorpidae, generally live in broad-leaf woodlands with plentiful damp leaf litter. Snow scorpionflies, family Boreidae, appear in winter and are to be seen on snowfields and on moss; the larvae being able to jump like [[flea]]s. Hangingflies, family Bittacidae, occur in forests, grassland and caves with high moisture levels. They mostly breed among mosses, in leaf litter and other moist places, but their reproductive habits have been little studied, and at least one species, ''[[Nannochorista philpotti]]'', has aquatic larvae.<ref name=Dunford/>

Adult mecopterans are mostly [[scavenger]]s, feeding on decaying vegetation and the soft bodies of dead invertebrates. ''[[Panorpa]]'' raid [[spider web]]s to feed on trapped insects and even the spiders themselves, and hangingflies capture flies and moths with their specially modified legs. Some groups consume [[pollen]], [[nectar]], [[midge]] larvae, [[carrion]] and moss fragments.<ref name=Dunford/> Most mecopterans live in moist environments; in hotter climates, the adults may therefore be active and visible only for short periods of the year.<ref name=IIBD/>

===Mating behaviour===
[[File:Panorpa communis copula.jpg|thumb|left|''[[Panorpa communis]]'' mating]]

Various courtship behaviours have been observed among mecopterans, with males often emitting [[pheromone]]s to attract mates. The male may provide an edible gift such as a dead insect or a brown salivary secretion to the female. Some boreids have hook-like wings which the male uses to pick up and place the female on his back while copulating. Male panorpids vibrate their wings or even [[stridulate]] while approaching a female.<ref name=Dunford/>

[[File:Bittacidae_fg1.jpg|thumb|upright|[[Bittacidae|Hangingflies]] have distinct mating behaviour.]]

Hangingflies (Bittacidae) provide a nuptial meal in the form of a captured insect prey, such as a caterpillar, bug, or fly. The male attracts a female with a pheromone from vesicles on his abdomen; he retracts these once a female is nearby, and presents her with the prey. While she evaluates the gift, he locates her genitalia with his. If she stays to eat the prey, his genitalia attach to hers, and the female lowers herself into an upside-down hanging position, and eats the prey while mating. Larger prey result in longer mating times. In ''Hylobittacus apicalis'', prey  {{convert|3|to|14|mm|in}} long give between 1 and 17 minutes of mating. Larger males of that species give prey as big as houseflies, earning up to 29 minutes of mating, maximal sperm transfer, more oviposition, and a refractory period during which the female does not mate with other males: all of these increase the number of offspring the male is likely to have.<ref>{{cite book |author1=Gullan, P. J. |author2=Cranston, P. S. |date=2010 |title=The Insects: An Outline of Entomology |publisher=Wiley |edition=4th |isbn=978-1-118-84615-5 |page=129}}</ref>

===Life-cycle===
The female lays the eggs in close contact with moisture, and the eggs typically absorb water and increase in size after deposition. In species that live in hot conditions, the eggs may not hatch for several months, the larvae only emerging when the dry season has finished. More typically, however, they hatch after a relatively short period of time. The larvae are usually quite [[caterpillar]]-like, with short, clawed, true legs, and a number of abdominal [[proleg]]s. They have sclerotised heads with mandibulate mouthparts. Larvae possess compound eyes, which is unique among [[holometabolous]] insects.<ref>{{Cite journal|last1=Chen|first1=Qing-Xiao|last2=Hua|first2=Bao-Zhen|date=2016-06-03|title=Ultrastructure and Morphology of Compound Eyes of the Scorpionfly Panorpa dubia (Insecta: Mecoptera: Panorpidae)|journal=PLOS ONE|volume=11|issue=6|pages=e0156970|doi=10.1371/journal.pone.0156970|issn=1932-6203|pmc=4892548|pmid=27258365|bibcode=2016PLoSO..1156970C|doi-access=free}}</ref> The tenth abdominal segment bears either a suction disc, or, less commonly, a pair of hooks. They generally eat vegetation or scavenge for dead insects, although some predatory larvae are known.  The larva crawls into the soil or decaying wood to [[pupa]]te, and does not spin a cocoon. The pupae are [[Holometabolism#Pupa|exarate]], meaning the limbs are free of the body, and are able to move their mandibles, but are otherwise entirely nonmotile. In drier environments, they may spend several months in [[diapause]], before emerging as adults once the conditions are more suitable.<ref name=IIBD/>

[[File:Skorpionsfliege Panorpa communis male genital.jpg|thumb|The raised [[scorpion]]-like tail of the male has earned the scorpionflies a sinister reputation, but they do not sting.]]

==Interaction with humans==

[[Forensic entomology]] makes use of scorpionflies' habit of feeding on human [[corpse]]s. In areas where the family Panorpidae occurs, such as the eastern United States, these scorpionflies can be the first insects to arrive at a donated human cadaver<!-- observed (by the entomologist Natalie Lindgren) at the Southeast Texas Applied Forensic Science Facility near [[Huntsville, Texas]]-->, and remain on a corpse for one or two days. The presence of scorpionflies thus indicates that a body must be fresh.<ref>{{cite news |last1=Rutsch |first1=Poncie |title=Finding Crime Clues In What Insects Had For Dinner |url=https://www.npr.org/sections/health-shots/2015/01/22/379091257/finding-crime-clues-in-what-insects-had-for-dinner |newspaper=NPR |access-date=22 June 2015 |date=22 January 2015}}</ref><ref name=STAFS/>

Scorpionflies are sometimes described as looking "sinister", particularly from the male's raised "tail" resembling a [[scorpion]]'s sting.<ref>{{cite web |title=Weirdest Looking Bugs |url=http://www.enkivillage.com/weirdest-bugs.html |publisher=EnkiVillage |access-date=22 June 2015|date=2015-05-13 }}</ref> A popular but incorrect belief is that they can sting with their tails.<ref>{{cite web |last1=Newton |first1=Blake |title=Scorpionflies & Hangingflies|url=http://www.uky.edu/Ag/CritterFiles/casefile/insects/scorpionflies/scorpionflies.htm|publisher=University of Kentucky|access-date=25 February 2017}}</ref>{{Clear}}

==References==
{{Reflist|30em}}

==External links==
{{Wikispecies|Mecoptera}}
{{Commons}}
* [http://tolweb.org/tree?group=Mecoptera&contgroup=Endopterygota Mecoptera at the Tree of Life]
* [https://web.archive.org/web/20050818104810/http://myrmecos.net/insects/mecoptera.html Mecoptera image gallery at myrmecos.net]
* [https://www.youtube.com/watch?v=TH9yFQXmlik Video of Mecoptera from Austria]
* [https://www.bbc.co.uk/nature/15061273 Mecoptera in UK on BBC wildlife website (third image in)]

{{Orders of Insects}}
{{Mecoptera & Siphonaptera}}
{{Authority control}}
{{Taxonbar|from=Q205301}}

[[Category:Mecoptera| ]]
[[Category:Insect orders]]
[[Category:Extant Permian first appearances]]
[[Category:Paraphyletic groups]]