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{{Short description|Suborder of insects}}
{{About|the hymenopteran suborder Symphyta|the moth genus|Symphyta (moth){{!}}''Symphyta'' (moth)}}
{{Use dmy dates|date=April 2017}}
{{Good article}}
{{Paraphyletic group
| fossil_range = {{fossil_range|Triassic|Present}}
| image = XN Tenthredo mesomela.jpg
| image_caption = ''[[Tenthredo mesomela]]''
|taxon=Symphyta
| auto = yes
| authority = [[Carl Eduard Adolph Gerstaecker|Gerstaecker]], 1867<ref name="Gerstaecker_1867">{{cite journal |last=Gerstaecker |first=C.E.A. |title=Ueber die Gattung Oxybelus Latr. und die bei Berlin vorkommenden Arten derselben |journal=Zeitschrift für die Gesammten Naturwissenschaften |date=1867 |volume=30 |issue=7 |pages=1–144 |url=https://www.biodiversitylibrary.org/item/102864#page/17/mode/1up |language=de}}</ref>
|includes=
*[[Anaxyeloidea]]<ref name="Aguiar_et_al_2013">{{cite journal |last1=Aguiar |first1=A.P. |last2=Deans |first2=A.R. |last3=Engel |first3=M.S. |last4=Forshage |first4=M. |last5=Huber |first5=J.T. |last6=Jennings |first6=J.T. |last7=Johnson |first7=N.F. |last8=Lelej|first8=A.S. |last9=Longino |first9=J.T. |last10=Lohrmann |first10=V. |last11=Mikó |first11=I. |last12=Ohl |first12=M. |last13=Rasmussen |first13=C. |last14=Taeger |first14=A. |last15=Yu |first15=D.S.K. |title=Order Hymenoptera ''In'': Zhang, Z.-Q. (ed.) Animal biodiversity: an outline of higher-level classification and survey of taxonomic richness |journal=Zootaxa |date=2013 |volume=3703 |issue=1 |pages=51–62 |doi=10.11646/zootaxa.3703.1.12 |pmid=26146682|doi-access=free}}</ref>
*[[Cephoidea]]<ref name="Aguiar_et_al_2013"/>
*{{extinct}}[[Karatavitoidea]]<ref name="Aguiar_et_al_2013"/>
*[[Orussoidea]]<ref name="Aguiar_et_al_2013"/>
*[[Pamphilioidea]]<ref name="Aguiar_et_al_2013"/>
*[[Siricoidea]]<ref name="Aguiar_et_al_2013"/>
*[[Tenthredinoidea]]<ref name="Aguiar_et_al_2013"/>
*[[Xiphydrioidea]]<ref name="Aguiar_et_al_2013"/>
*[[Xyeloidea]]<ref name="Aguiar_et_al_2013"/>
|excludes= 
*[[Apocrita]]
}}
[[File:Sawfly (Nematus septentrionalis) larvae.jpg|thumb|Larvae of ''Nematus septentrionalis'']]
'''Sawflies''' are [[wasp]]-like insects that are in the [[suborder]] '''Symphyta''' within the order [[Hymenoptera]], alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the [[ovipositor]], which the females use to cut into the plants where they lay their eggs. The name is associated especially with the [[Tenthredinoidea]], by far the largest [[Taxonomic rank#Ranks in zoology|superfamily]] in the suborder, with about 7,000 known species; in the entire suborder, there are 8,000 described species in more than 800 genera. Symphyta is [[paraphyly|paraphyletic]], consisting of several [[Basal (phylogenetics)|basal]] groups within the order Hymenoptera, each one rooted inside the previous group, ending with the [[Apocrita]] which are not sawflies.

The primary distinction between sawflies and the Apocrita – the ants, bees, and wasps – is that the adults lack a "wasp waist", and instead have a broad connection between the [[abdomen]] and the [[Thorax (insect anatomy)|thorax]]. Some sawflies are [[Batesian mimicry|Batesian mimics]] of wasps and bees, and the ovipositor can be mistaken for a [[stinger]]. Sawflies vary in length, most measuring {{convert|2.5|to|20|mm|in|frac=32}}; the largest known sawfly measured {{cvt|55|mm|in|frac=4}}. The larvae are caterpillar-like, but can be distinguished by the number of [[proleg]]s and the absence of [[crochet (insect anatomy)|crochets]] in sawfly larvae. The great majority of sawflies are [[herbivore|plant-eating]], though the members of the superfamily [[Orussoidea]] are [[parasitoid|parasitic]].

Predators include birds, insects and small animals. The larvae of some species have [[anti-predator adaptation]]s such as regurgitating irritating liquid and clustering together for safety in numbers. Sawflies are hosts to many parasitoids, most of which are Hymenoptera, the rest being [[Diptera]].

Adult sawflies are short-lived, with a life expectancy of 7–9 days, though the larval stage can last from months to years, depending on the species. [[Parthenogenesis|Parthenogenetic]] females, which do not need to mate to produce fertilised eggs, are common in the suborder, though many species have males. The adults feed on pollen, nectar, honeydew, sap, other insects, including hemolymph of the larvae hosts; they have mouth pieces adapted to these types of feeding.<ref>{{cite journal |doi=10.1111/j.1095-8312.2000.tb00204.x | volume=70 | title=Mouthpart evolution in adults of the basal, 'symphytan', hymenopteran lineages | year=2000 | journal=Biological Journal of the Linnean Society | pages=121–146 | last1=Jervis | first1=Mark | last2=Vilhelmsen | first2=Lars | doi-access=free}}</ref>

Sawflies go through a [[Metamorphosis|complete metamorphosis]] with four distinct life stages – egg, larva, pupa and adult. The female uses her ovipositor to drill into plant material (or, in the case of Orussoidea, other insects) and then lays eggs in groups called rafts or pods. After hatching, larvae feed on plants, often in groups. As they approach adulthood, the larvae seek a protected spot to pupate, typically in bark or the soil. Large populations of species such as the [[Diprion pini|pine sawfly]] can cause substantial damage to economic [[forestry]], while others such as the [[iris sawfly]] are major pests in [[horticulture]]. Outbreaks of sawfly larvae can defoliate trees and may cause dieback, stunting or death. Sawflies can be controlled through the use of insecticides, natural predators and parasitoids, or mechanical methods.

Sawflies first appeared 250&nbsp;million years ago in the [[Triassic]]. The oldest superfamily, the [[Xyeloidea]], has existed into the presents. Over 200{{nbsp}}million years ago, a lineage of sawflies evolved a parasitoid lifestyle, with carnivorous larvae that ate the eggs or larvae of other insects. Sawflies are distributed globally, though they are more diverse in the northernmost hemispheres.

==Etymology==
[[File:Dolerus nitens.jpg|thumb|Sawfly laying eggs in a plant, using the serrated [[saw]]-like [[ovipositor]] for which the group is named]]

The suborder name "Symphyta" derives from the Greek word {{transliteration|grc|symphyton}}, meaning 'grown together', referring to the group's distinctive lack of a wasp waist between prostomium and peristomium.<ref>{{cite dictionary |title=Symphyta |url=https://www.merriam-webster.com/dictionary/Symphyta |dictionary=Merriam-Webster |access-date=2 December 2016}}</ref> Its common name, "sawfly", derives from the [[saw]]-like ovipositor that is used for egg-laying, in which a female makes a slit in either a stem or plant leaf to deposit the eggs.<ref name=AusMus/> The first known use of this name was in 1773.<ref>{{cite web |title=Sawfly |url=http://www.merriam-webster.com/dictionary/sawfly|publisher=Merriam-Webster Online Dictionary |access-date=29 November 2016}}</ref> Sawflies are also known as "wood-wasps".<ref name="Gordh_Headrick_2011">{{cite book|last1=Gordh|first1=G.|last2=Headrick|first2=D.H.|title=A Dictionary of Entomology|date=2011|publisher=CABI|location=Wallingford|isbn=978-1-84593-542-9|pages= 1344|edition=2nd}}</ref>

==Phylogeny==
[[File:Entomologie1.jpg|thumb|left|[[Carl Eduard Adolph Gerstaecker|Carl Gerstaecker]] established the suborder Symphyta]]

In his original description of [[Hymenoptera]] in 1863, German zoologist [[Carl Eduard Adolph Gerstaecker|Carl Gerstaecker]] divided them into three groups, ''Hymenoptera aculeata'', ''Hymenoptera apocrita'' and ''Hymenoptera phytophaga''.<ref>{{cite book |last1=Carus |first1=J.V. |last2=Gerstaecker |first2=C.E.A. |title=Handbuch der zoologie: bd. Arthropoden, bearb. von A. Gerstaecker. Raderthiere, würmer, echinodermen, coelenteraten und protozoen, bearb. von J. Victor Carus. 1863 |date=1863 |publisher=Engelmann |location=Leipzig, Germany |language=de |url=https://books.google.com/books?id=8m1MAAAAMAAJ |page=189 |doi=10.5962/bhl.title.1399 |oclc=2962429}}</ref> However, four years later in 1867, he described just two groups, ''H. apocrita'' [[syn.]] ''genuina'' and ''H. symphyta'' syn. ''phytophaga''.<ref name="Gerstaecker_1867"/> Consequently, the name Symphyta is given to Gerstaecker as the [[zoological authority]]. In his description, Gerstaecker distinguished the two groups by the transfer of the first abdominal segment to the thorax in the [[Apocrita]], compared to the Symphyta. Consequently, there are only eight dorsal half segments in the Apocrita, against nine in the Symphyta. The larvae are distinguished in a similar way.<ref>{{cite book|last1=Dallas|first1=W.S.|title=''Insecta'' In'': Günther, A.C.L.G '' The Zoological Record: Insecta, Volumes 3-4|date=1867|publisher=John van Voorst|location=London, UK|url=https://books.google.com/books?id=i8pDAQAAMAAJ&pg=PA307|oclc= 6344527|pages=307}}</ref>
 
The Symphyta have therefore traditionally been considered, alongside the Apocrita, to form one of two [[suborders]] of Hymenoptera.{{sfn|Goulet|Huber|1993|p=5}}<ref name="Sharkey_2007">{{cite journal|last1=Sharkey|first1=M.J.|title=Phylogeny and classification of Hymenoptera|journal=Zootaxa|date=2007|volume=1668|pages=521–548|url=http://www.mapress.com/zootaxa/2007f/zt01668p548.pdf|doi=10.11646/zootaxa.1668.1.25}}</ref> Symphyta are the more primitive group, with comparatively complete [[Insect wing#Venation|venation]], larvae that are largely [[Herbivore|phytophagous]], and without a "wasp-waist", a [[symplesiomorphic]] feature. Together, the Symphyta make up less than 10% of hymenopteran species.<ref name="Mao_et_al_2015">{{cite journal|last1=Mao|first1=M.|last2=Gibson|first2=T.|last3=Dowton|first3=M.|title=Higher-level phylogeny of the Hymenoptera inferred from mitochondrial genomes|journal=Molecular Phylogenetics and Evolution|date=2015|volume=84|pages=34–43|doi=10.1016/j.ympev.2014.12.009|pmid=25542648|bibcode=2015MolPE..84...34M }}</ref> While the terms sawfly and Symphyta have been used synonymously, the Symphyta have also been divided into three groups, true sawflies (phyllophaga), [[woodwasps]] or xylophaga (Siricidae), and [[Orussidae]]. The three groupings have been distinguished by the true sawflies' ventral serrated or saw-like ovipositor for sawing holes in vegetation to deposit eggs, while the woodwasp ovipositor penetrates wood and the Orussidae behave as external [[parasitoids]] of [[wood-boring]] [[Coleoptera|beetles]]. The woodwasps themselves are a [[paraphyletic]] ancestral [[evolutionary grade|grade]]. Despite these limitations, the terms have utility and are common in the literature.<ref name="Sharkey_2007"/>

While most hymenopteran superfamilies are [[monophyletic]], as is Hymenoptera, the Symphyta has long been seen to be paraphyletic.<ref>{{cite journal|last1=Sharkey|first1=M.J.|last2=Carpenter|first2=J.M.|last3=Vilhelmsen|first3=L.|last4=Heraty|first4=J.|last5=Liljeblad|first5=J.|last6=Dowling|first6=A.P.G.|last7=Schulmeister|first7=S.|last8=Murray|first8=D.|last9=Deans|first9=A.R.|last10=Ronquist|first10=F.|last11=Krogmann|first11=L.|last12=Wheeler|first12=W.C.|title=Phylogenetic relationships among superfamilies of Hymenoptera|journal=Cladistics|date=2012|volume=28|issue=1|pages=80–112|doi=10.1111/j.1096-0031.2011.00366.x|pmid=34861753|url=http://escholarship.org/uc/item/7dp042pr|citeseerx=10.1.1.721.8852|s2cid=33628659}}</ref><ref name="Song_et_al_2016">{{cite journal|last1=Song|first1=S.-N.|last2=Tang|first2=P.|last3=Wei|first3=S.-J.|last4=Chen|first4=X.-X.|title=Comparative and phylogenetic analysis of the mitochondrial genomes in basal hymenopterans|journal=Scientific Reports|date=2016|volume=6|pages=20972|bibcode=2016NatSR...620972S|doi=10.1038/srep20972|pmid=26879745|pmc=4754708}}</ref> [[Cladistic]] methods and [[molecular phylogenetics]] are improving the understanding of relationships between the superfamilies, resulting in revisions at the level of superfamily and family.<ref>{{cite book|last1=Hennig|first1=W.|title=Die Stammesgeschichte der Insekten|date=1969|publisher=Waldemar Kramer|location=Frankfurt|pages=291, 359|asin=B0000BRK5P|oclc=1612960}}</ref> The Symphyta are the most primitive ([[basal (phylogenetics)|basal]]) [[taxon|taxa]] within the Hymenoptera (some going back 250&nbsp;million years), and one of the taxa within the Symphyta gave rise to the monophyletic suborder Apocrita ([[wasp]]s, [[bee]]s, and [[ant]]s).<ref name="Mao_et_al_2015"/><ref name="Song_et_al_2016"/> In cladistic analyses the Orussoidea are consistently the [[sister group]] to the Apocrita.<ref name="Sharkey_2007"/><ref name="Mao_et_al_2015"/>

The oldest unambiguous sawfly fossils date back to the [[Middle Triassic|Middle]] or [[Late Triassic|Late]] Triassic. These fossils, from the family [[Xyelidae]], are the oldest of all Hymenoptera.<ref>{{cite book |last1=Hermann|first1=Henry R. |title=Social Insects |date=1979|publisher=Elsevier Science |location=Oxford |isbn=978-0-323-14979-2|page=85|volume=1}}</ref> One fossil, ''Archexyela ipswichensis'' from Queensland is between 205.6 and 221.5{{nbsp}}million years of age, making it among the oldest of all sawfly fossils.<ref>{{cite journal|last1=Engel|first1=M.S.|title=A new sawfly from the Triassic of Queensland (Hymenoptera: Xyelidae)|journal=Memoirs of the Queensland Museum|date=2005|volume=51|issue=2|page=558}}</ref> More Xyelid fossils have been discovered from the [[Middle Jurassic]] and the [[Cretaceous]], but the family was less diverse then than during the [[Mesozoic]] and [[Tertiary]]. The subfamily [[Xyelinae]] were plentiful during these time periods, in which Tertiary faunas were dominated by the tribe Xyelini; these are indicative of a humid and warm climate.<ref>{{cite journal|last1=Wang|first1=M. |last2=Rasinitsyn |first2=A.P. |last3=Ren |first3=Dong |title=Two new fossil sawflies (Hymenoptera, Xyelidae, Xyelinae) from the Middle Jurassic of China |journal=Acta Geologica Sinica|date=2014 |volume=88|issue=4 |pages=1027–1033 |doi=10.1111/1755-6724.12269|bibcode=2014AcGlS..88.1027W |s2cid=129371522 }}</ref><ref>{{cite journal |last1=Wang |first1=M. |last2=Gao |first2=T. |last3=Shih |first3=C. |last4=Rasinitsyn |first4=A.P. |last5=Ren |first5=D. |title=The diversity and phylogeny of Mesozoic Symphyta (Hymenoptera) from Northeastern China |journal=Acta Geologica Sinica |date=2016 |volume=90 |issue=1 |pages=376–377 |doi=10.1111/1755-6724.12662|bibcode=2016AcGlS..90..376W |s2cid=87932664 }}</ref><ref>{{cite journal |last1=Rasnitsyn |first1=A.P. |title=Ontology of evolution and methodology of taxonomy |journal=Paleontological Journal |date=2006 |volume=40 |issue=S6 |pages=S679–S737 |doi=10.1134/S003103010612001X|bibcode=2006PalJ...40S.679R |s2cid=15668901 }}</ref>

The cladogram is based on Schulmeister 2003.<ref>{{cite journal |author=Schulmeister, S. |date=2003 |title=Simultaneous analysis of basal Hymenoptera (Insecta), introducing robust-choice sensitivity analysis |journal=Biological Journal of the Linnean Society |volume=79 |issue=2 |pages=245–275 |doi=10.1046/j.1095-8312.2003.00233.x|doi-access=free }}</ref><ref>{{cite web |last1=Schulmeister |first1=S. |title=Symphyta |url=http://susanne.schulmeister.com/Symphyta.html |access-date=28 November 2016 |archive-date=21 June 2010 |archive-url=https://web.archive.org/web/20100621021510/http://susanne.schulmeister.com/Symphyta.html |url-status=dead }}</ref>

{{cladogram|title=Symphyta within Hymenoptera|caption=Symphyta (red bar) are paraphyletic as Apocrita are excluded.|align=left
|clades=
{{Barlabel|labelwidth=5|size=7|at=3.5|label=Symphyta|colour=red
|cladogram=
{{clade | style = font-size:100%; line-height:100%; width:50em;
|label1=[[Hymenoptera]] |sublabel1=250mya
|1={{clade
   |1=[[Xyeloidea]]  ([[Triassic]]–present) [[File:Xyelapusilla.jpg|70px]] |barbegin1=red 
   |2={{clade
      |1=[[Tenthredinoidea]] [[File:Diprionpini crop.jpg|70px]] |bar1=red
      |2={{clade
         |1=[[Pamphilioidea]] [[File:Caenolyda reticulata (cropped).jpg|70px]] |bar1=red
         |2={{clade
            |1=[[Cephoidea]] (stem sawflies) [[File:Hartigia linearis.jpg|70px]] |bar1=red
            |2={{clade
               |1=[[Siricoidea]] (horntails or wood wasps) [[File:Hymenoptera Vielfalt Horntail.jpg|85px]] |bar1=red
               |2={{clade
                  |1=[[Xiphydrioidea]] (wood wasps) [[File:Xiphydria prolongata crop.jpg|70px]] |bar1=red
                  |label2=''parasitism'' 
                  |2={{clade
                     |1=[[Orussoidea]]  ([[parasite|parasitic]] wood wasps) [[File:Orussus coronatus.jpg|65px]]|barend1=red 
                     |label2= ''wasp waist'' |sublabel2=200mya
                     |2=[[Apocrita]] ([[ant]]s, [[bee]]s, [[wasp]]s) [[File:Specimen of Podalonia tydei (Le Guillou, 1841).jpg|80px]]
                     }}
                  }}
               }}
            }}
         }}
      }}
   }}
}}
}}
}}{{clear}}

=== Taxonomy ===

[[File:Syntexis libocedrii.jpg|thumb|upright=1.25|[[Anaxyeloidea]]: ''[[Syntexis libocedrii]]'']]

There are approximately 8,000 species of sawfly in more than 800 genera, although new species continue to be discovered.{{sfn|Capinera|2008|pp=3250–3252}}<ref>{{cite journal |last1=Taeger|first1=A.|last2=Blank|first2=S.M.|last3=Liston|first3=A.|title=World catalog of symphyta (Hymenoptera) |journal=Zootaxa |date=2010 |volume=2580 |pages=1–1064 |url=https://www.researchgate.net/publication/236608283|issn=1175-5334|doi=10.11646/zootaxa.2580.1.1}}</ref><ref>{{cite journal|last1=Skvarla|first1=M.J.|last2=Smith|first2=D.R.|last3=Fisher|first3=D.M.|last4=Dowling|first4=A.P.G.|title=Terrestrial arthropods of Steel Creek, Buffalo National River, Arkansas. II. Sawflies (Insecta: Hymenoptera: "''Symphyta''")|journal=Biodiversity Data Journal|date=2016|volume=4|issue=4|pages=e8830|doi=10.3897/BDJ.4.e8830|pmid=27222635|pmc=4867044 |doi-access=free }}</ref> However, earlier studies indicated that 10,000 species grouped into about 1,000 genera were known.<ref>{{cite journal|last1=Taeger|first1=A.|last2=Blank|first2=S.M.|title=Kommentare zur Taxonomie der Symphyta (Hymenoptera): Vorarbeiten zu einem Katalog der Pflanzenwespen, Teil 1|journal=Beiträge zur Entomologie|date=1996|volume=46|issue=2|pages=251–275|language=de}}</ref> Early [[phylogenies]] such as that of [[Alexandr Rasnitsyn]], based on morphology and behaviour, identified nine [[clades]] which did not reflect the historical superfamilies.<ref>{{cite journal|last1=Rasnitsyn|first1=A.P.|title=An outline of evolution of hymenopterous insects (order Vespida)|journal=Oriental Insects|date=1988|volume=22|pages=115–145|doi=10.1080/00305316.1988.11835485}}</ref> Such classifications were replaced by those using molecular methods, starting with Dowton and Austin (1994).<ref>{{cite journal|last1=Dowton|first1=M.|last2=Austin|first2=A.D.|title=Molecular phylogeny of the insect order Hymenoptera: apocritan relationships|journal=Proceedings of the National Academy of Sciences of the United States of America |date=1994|volume=91|issue=21|pages=9911–9915|bibcode=1994PNAS...91.9911D|doi=10.1073/pnas.91.21.9911|pmc=44927|pmid=7937916|doi-access=free}}</ref> As of 2013, the Symphyta are treated as nine [[Superfamily (zoology)|superfamilies]] (one extinct) and 25 families. Most sawflies belong to the Tenthredinoidea superfamily, with about 7,000 species worldwide. Tenthredinoidea has six families, of which [[Tenthredinidae]] is by far the largest with some 5,500 species.<ref name="Aguiar_et_al_2013"/>{{sfn|Goulet|Huber|1993|p=104}}

Extinct taxa are indicated by a [[dagger (typography)#Modern usage|dagger]] ({{extinct}}).

====Superfamilies and families====
* Superfamily [[Anaxyeloidea]] {{small|(Martynov, 1925)}}
** Family [[Anaxyelidae]] {{small|(Martynov, 1925)}} (1 species) and {{extinct}}12 genera
* Superfamily [[Cephoidea]] {{small|(Newman, 1834)}} (1 and {{extinct}}1 family)
** Family [[Cephoidea|Cephidae]] {{small|(Newman, 1834)}} (21 genera, 160 [[species|spp.]] and {{extinct}}3 genera 
* Superfamily {{extinct}}[[Karatavitoidea]] {{small|(Rasnitsyn, 1963)}} (1 family)
** Family {{extinct}}[[Karatavitidae]] {{small|(Rasnitsyn, 1963)}} (7 genera)
* Superfamily [[Orussoidea]] {{small|(Newman, 1834)}} (1 and {{extinct}}1 family)
** Family [[Orussidae]] {{small|(Newman, 1834)}} (16 genera, 82 spp.) and {{extinct}}3 genera
* Superfamily [[Pamphilioidea]] {{small|(Cameron, 1890)}} (2 and {{extinct}}1 families) ([[syn.]] Megalodontoidea)
** Family [[Megalodontesidae]] {{small|(Konow, 1897)}} (1 genera, 42 spp.) and {{extinct}}1 genus
** Family [[Pamphiliidae]] {{small|(Cameron, 1890)}} (10 genera, 291 spp.) and {{extinct}}3 genera
* Superfamily [[Siricoidea]] {{small|(Billberg, 1820)}} (2 and {{extinct}}5 families)
** Family [[Siricidae]] {{small|(Billberg, 1820)}} (11 genera, 111 spp.) and {{extinct}}9 genera
* Superfamily [[Tenthredinoidea]] {{small|(Latreille, 1803)}} (6 and {{extinct}}2 families)
** Family [[Argidae]] {{small|(Konow, 1890)}} (58 genera, 897 spp.) and {{extinct}}1 genus
** Family [[Blasticotomidae]]{{small|(Thomson, 1871)}} (2 genera, 12 spp.) and {{extinct}}1 genus
** Family [[Cimbicidae]] {{small|(W. Kirby, 1837)}} (16 genera, 182 spp.) and {{extinct}}6 genera
** Family [[Diprionidae]] {{small|(Rohwer, 1910)}} (11 genera, 136 spp.) and {{extinct}}2 genera
** Family [[Pergidae]] {{small|(Rohwer, 1911)}} (60 genera, 442 spp.)
** Family [[Tenthredinidae]] {{small|(Latreille, 1803)}} (400 genera, 5,500 spp.) and {{extinct}}14 genera
* Superfamily [[Xiphydrioidea]] {{small|(Leach, 1819)}} 
** Family [[Xiphydriidae]] {{small|(Leach, 1819)}} (28 genera, 146 spp.)
* Superfamily [[Xyeloidea]] {{small|(Newman, 1834)}}
** Family [[Xyelidae]] {{small|(Newman, 1834)}} (5 genera, 63 spp.) and {{extinct}}47 genera

==Description==

{{multiple image
|align    = left
|image1   = Urocerus gigas5.jpg
|caption1 = Giant horntail, ''[[Urocerus gigas]]'', a [[Batesian mimicry|Batesian mimic]] of a hornet, [[oviposition|ovipositing]]. It does not sting.
|image2   = Hornisse am Apfel IMG 3004.JPG
|caption2 = The [[European hornet]] is a wasp-waisted [[Apocrita]]n with a sting, not a Symphytan.
}}

Many species of sawfly have retained their ancestral attributes throughout time, specifically their plant-eating habits, wing veins and the unmodified abdomen, where the first two segments appear like the succeeding segments.{{sfn|Goulet|Huber|1993|pp=5–6}} The absence of the narrow wasp waist distinguishes sawflies from other members of hymenoptera, although some are [[Batesian mimicry|Batesian mimics]] with {{not a typo|[[animal coloration|coloration]]}} similar to wasps and bees, and the ovipositor can be mistaken for a stinger.<ref name="Burton_Burton_2002"/> Most sawflies are stubby and soft-bodied, and fly weakly.{{sfn|Goulet|Huber|1993|p=6}} Sawflies vary in length: ''Urocerus gigas'', which can be mistaken as a wasp due to its black-and-yellow striped body, can grow up to {{cvt|20|mm|in|frac=8}} in length, but among the largest sawflies ever discovered was ''[[Hoplitolyda duolunica]]'' from the Mesozoic, with a body length of {{cvt|55|mm|in|frac=4}} and a wingspan of {{cvt|92|mm|in|frac=4}}.<ref name="Burton_Burton_2002"/><ref>{{cite journal |last1=Gao |first1=T. |last2=Shih |first2=C. |last3=Rasnitsyn |first3=A.P. |last4=Ren |first4=D. |last5=Laudet |first5=V. |title=''Hoplitolyda duolunica'' gen. et sp. nov. (Insecta, Hymenoptera, Praesiricidae), the hitherto largest sawfly from the Mesozoic of China |journal=PLOS ONE |date=2013 |volume=8 |issue=5 |pages=e62420 |doi=10.1371/journal.pone.0062420 |pmid=23671596 |pmc=3643952 |bibcode=2013PLoSO...862420G|doi-access=free }}</ref> The smaller species only reach lengths of {{cvt|2.5|mm|in|frac=32}}.<ref>{{cite book|last1=Benson|first1=R.B.|title=Handbooks for the Identification of British Insects: VI Hymenoptera 2 Symphyta Section (b)|date=1952|location=London|publisher=Royal Entomological Society of London|page=51|url=http://www.royensoc.co.uk/sites/default/files/Vol06_Part02b.pdf|oclc=429798429|url-status=dead|archive-url=https://web.archive.org/web/20150924092616/http://www.royensoc.co.uk/sites/default/files/Vol06_Part02b.pdf|archive-date=24 September 2015|df=dmy-all}}</ref>

Heads of sawflies vary in size, shape and sturdiness, as well as the positions of the eyes and antennae. They are characterised in four head types: open head, maxapontal head, closed head and genapontal head. The open head is simplistic, whereas all the other heads are derived.{{sfn|Ross|1937|p=11}} The head is also hypognathous, meaning that the lower mouthparts are directed downwards. When in use, the mouthparts may be directed forwards, but this is only caused when the sawfly swings its entire head forward in a pendulum motion.{{sfn|Ross|1937|p=9}} Unlike most primitive insects, the [[Suture (anatomy)|suture]]s (rigid joints between two or more hard elements on an organism) and [[sclerite]]s (hardened body parts) are obsolescent or absent. The [[Clypeus (arthropod anatomy)|clypeus]] (a sclerite that makes up an insects "face") is not divided into a pre- and postclypeus, but rather separated from the front.{{sfn|Ross|1937|p=10}} The antennal sclerites are fused with the surrounding head capsule, but these are sometimes separated by a suture. The number of segments in the [[Antenna (biology)|antennae]] vary from six in the Accorduleceridae to 30 or more in the Pamphiliidae.{{sfn|Ross|1937|p=21}} The [[Arthropod eye|compound eyes]] are large with a number of facets, and there are three [[Simple eye in invertebrates|ocelli]] between the dorsal portions of the compound eyes.{{sfn|Ross|1937|p=10}} The [[tentorium]] comprises the whole inner skeleton of the head.{{sfn|Ross|1937|p=13}}

Three segments make up the thorax: the [[mesothorax]], [[metathorax]] and [[prothorax]], as well as the exoskeletal plates that connect with these segments.{{sfn|Ross|1937|pp=22–29}} The legs have spurs on their fourth segments, the tibiae.{{sfn|Ross|1937|p=27}} Sawflies have two pairs of [[Transparency and translucency|translucent]] wings. The fore and hind wings are locked together with hooks.<ref>{{cite book |last1=Adams |first1=C. |last2=Early |first2=M. |last3=Brook |first3=J. |last4=Bamford |first4=K. |title=Principles of Horticulture: Level 2 |date=2014 |publisher=Routledge |location=New York, New York |isbn=978-1-317-93777-7 |page=18}}</ref> Parallel development in sawfly wings is most frequent in the anal veins. In all sawflies, 2A and 3A tend to fuse with the first anal vein. This occurs in several families including Argidae, Diprionidae and Cimbicidae.{{sfn|Ross|1937|p=29}}

[[File:Abia sericea 2.jpg|thumb|right|[[Aposematic]]ally coloured [[caterpillar]]-like [[larva]] of ''[[Abia sericea]]'']]

The larvae of sawflies are easily mistaken for [[lepidoptera]]n larvae (caterpillars). However, several morphological differences can distinguish the two: while both larvae share three pairs of thoracic legs and an apical pair of abdominal [[proleg]]s, lepidopteran caterpillars have four pairs of prolegs on abdominal segments 3–6 while sawfly larvae have five pairs of prolegs located on abdominal segments 2–6; [[crochet (insect anatomy)|crochets]] are present on lepidopteran larvae, whereas on sawfly larvae they are not; the prolegs of both larvae gradually disappear by the time they burrow into the ground, therefore making it difficult to distinguish the two; and sawfly larvae only have a single pair of minute eyes, whereas lepidopteran larvae have four to six eyes on each side of the head.{{sfn|Goulet|Huber|1993|p=5}}<ref name="Burton_Burton_2002"/> Sawfly larvae behave like lepidopteran larvae, walking about and eating foliage. Some groups have larvae that are eyeless and almost legless; these larvae make tunnels in plant tissues including wood.{{sfn|Goulet|Huber|1993|p=6}} Many species of sawfly larvae are strikingly coloured, exhibiting colour combinations such as black and white while others are black and yellow. This is a [[Aposematism|warning colouration]] because some larvae can secrete irritating fluids from glands located on their undersides.<ref name="Burton_Burton_2002"/>

== Distribution ==
Sawflies are widely distributed throughout the world.<ref>{{cite journal|last1=Looney|first1=C.|last2=Smith|first2=D.R|last3=Collman|first3=S.J.|last4=Langor|first4=D.W.|last5=Peterson|first5=M.A.|title=Sawflies (Hymenoptera, Symphyta) newly recorded from Washington State|journal=Journal of Hymenoptera Research|date=2016|volume=49|pages=129–159|doi=10.3897/JHR.49.7104|doi-access=free}}</ref> The largest family, the Tenthredinidae, with some 5,000 species, are found on all continents except Antarctica, though they are most abundant and diverse in the temperate regions of the northern hemisphere; they are absent from New Zealand and there are few of them in Australia. The next largest family, the [[Argidae]], with some 800 species, is also worldwide, but is most common in the tropics, especially in Africa, where they feed on woody and herbaceous [[angiosperm]]s. Of the other families, the [[Blasticotomidae]]<!--suggest some overlinking is sensible here--> and [[Megalodontidae]] are [[Palearctic]]; the Xyelidae, [[Pamphilidae]], [[Diprionidae]], [[Cimbicidae]], and [[Cephidae]] are [[Holarctic]], while the [[Siricidae]] are mainly Holarctic with some tropical species. The parasitic Orussidae are found worldwide, mostly in tropical and subtropical regions. The wood-boring [[Xiphydriidae]] are worldwide, but most species live in the subtropical parts of Asia.{{sfn|Capinera|2008|pp=3250–3252}}

==Behaviour and ecology==
[[File:Hartigia trimaculata larvae in rose stem (rose stem sawfly).jpg|thumb|left|[[Rose stem sawfly]] (''Hartigia trimaculata'') larva in a rose stem]]

Sawflies are mostly [[herbivores]], feeding on plants that have a high concentration of chemical defences. These insects are either resistant to the chemical substances, or they avoid areas of the plant that have high concentrations of chemicals.<ref>{{cite book |last1=Rosenthal |first1=G.A. |last2=Berenbaum |first2=M.R. |title=Herbivores: Their Interactions with Secondary Plant Metabolites |date=1991 |publisher=Elsevier Science |location=Oxford |isbn=978-0-323-13940-3 |page=190 |edition=2nd}}</ref> The larvae primarily feed in groups; they are [[folivores]], eating plants and fruits on native trees and shrubs, though some are parasitic.<ref name=AusMus>{{cite web|author1=Australian Museum|title=Animal Species: Sawflies|url=https://australian.museum/learn/animals/insects/sawflies/|access-date=11 August 2015|date=20 October 2009}}</ref><ref name=BBC>{{cite web|title=Sawflies (Tenthredinoidae)|url=https://www.bbc.co.uk/gardening/advice/pests_and_diseases/identifier.shtml?sawflies|publisher=BBC|date=2014|access-date=11 August 2015}}</ref><ref>{{cite journal|last1=Bandeili |first1=B. |last2=Müller |first2=C. |title=Folivory versus florivory—adaptiveness of flower feeding |journal=Naturwissenschaften |date=2009 |volume=97 |issue=1 |pages=79–88 |doi=10.1007/s00114-009-0615-9|pmid=19826770|bibcode=2010NW.....97...79B|s2cid=25877174 }}</ref> However, this is not always the case; Monterey pine sawfly (''[[Itycorsia]]'') larvae are solitary web-spinners that feed on [[Pinus radiata|Monterey pine]] trees inside a silken web.<ref name=Klein1994>{{cite journal|last1=Kleintjes|first1=P.K.|last2=Dahlsten|first2=D.L.|title=Foraging behaviour and nestling diet of Chestnut-Backed chickadees in monterey pine|journal=The Condor |date=1994 |volume=96 |issue=3|pages=647–653 |doi=10.2307/1369468|jstor=1369468|url=https://sora.unm.edu/sites/default/files/journals/condor/v096n03/p0647-p0653.pdf}}</ref> The adults feed on pollen and nectar.<ref name=BBC/>

[[File:Forde Caterpillars 2012.JPG|thumb|upright|[[Anti-predator adaptation]]: [[spitfire sawfly]] larvae grouped together for safety in numbers]]

Sawflies are eaten by a wide variety of predators. While many birds find the larvae distasteful, some such as the [[currawong]] (''Strepera'') and [[Saxicola|stonechat]]s (''Saxicola'') eat both adults and larvae.<ref>{{cite journal|last1=Cummins |first1=S.|last2=O'Halloran |first2=J. |title=An assessment of the diet of nestling Stonechats using compositional analysis: Coleoptera (beetles), Hymenoptera (sawflies, ichneumon flies, bees, wasps and ants), terrestrial larvae (moth, sawfly and beetle) and Arachnida (spiders and harvestmen) accounted for 81% of Stonechat nestling diet |journal=Bird Study |date=2002 |volume=49 |issue=2 |pages=139–145 |doi=10.1080/00063650209461258 |s2cid=86569805}}</ref><ref name=SA1992/> The larvae are an important food source for the chicks of several birds, including [[partridge]]s.<ref>{{Cite report |last1=Campbell |first1=L.H. |last2=Avery |first2=M.I. |last3=Donald |first3=P. |last4=Evans |first4=A.D. |last5=Green |first5=R.E. |last6=Wilson |first6=J.D. |date=1997 |title=A Review of the Indirect Effects of Pesticides on Birds |publisher=Joint Nature Conservation Committee, Report. no 227 |location=Peterborough, UK |url=http://jncc.defra.gov.uk/pdf/jncc227_ch3.pdf |page=27 |issn=0963-8091 |access-date=11 August 2015 |archive-date=22 December 2015 |archive-url=https://web.archive.org/web/20151222102548/http://jncc.defra.gov.uk/pdf/jncc227_ch3.pdf |url-status=dead }}</ref> Sawfly and moth larvae form one third of the diet of nestling [[corn bunting]]s (''Emberiza calandra''), with sawfly larvae being eaten more frequently on cool days.<ref>{{cite journal |last1=Brickle|first1=N.W. |last2=Harper |first2=D.G.C. |title=Diet of nestling Corn Buntings ''Miliaria calandra'' in southern England examined by compositional analysis of faeces |journal=Bird Study |date=1999|volume=46 |issue=3|pages=319–329 |doi=10.1080/00063659909461145 |doi-access=free |bibcode=1999BirdS..46..319B }}</ref> [[Black grouse]] (''Tetrao tetrix'') chicks show a strong preference for sawfly larvae.<ref name=Bstudy2001>{{cite journal|last1=Starling-Westerberg|first1=A.|title=The habitat use and diet of Black ''Grouse Tetrao tetrix'' in the Pennine hills of northern England|journal=Bird Study|date=2001 |volume=48 |issue=1 |pages=76–89 |doi=10.1080/00063650109461205 |doi-access=free |bibcode=2001BirdS..48...76S }}</ref><ref>{{cite journal |last1=Cayford |first1=J.T. |title=Distribution and habitat preferences of Black Grouse in commercial forests in Wales: conservation and management implications |journal=Proceedings of the International Union Game of Biologists Congress|date=1990 |volume=19 |pages=435–447}}</ref> Sawfly larvae formed 43% of the diet of [[chestnut-backed chickadee]]s (''Poecile rufescens'').<ref name=Klein1994/> Small carnivorous mammals such as the [[masked shrew]] (''Sorex cinereus''), the [[northern short-tailed shrew]] (''Blarina brevicauda'') and the [[Peromyscus maniculatus|deer mouse]] (''Peromyscus maniculatus'') predate heavily on sawfly cocoons.<ref>{{cite journal|last1=Holling|first1=C.S.|title=The components of predation as revealed by a study of small-mammal predation of the European Pine Sawfly |journal=The Canadian Entomologist|date=1959 |volume=91|issue=5 |pages=293–320 |doi=10.4039/Ent91293-5 |s2cid=53474917 |url=http://campus.lakeforest.edu/menke/PDFs/Bio373/Holling_1959_CanEnt.pdf}}</ref> Insects such as ants and certain species of predatory wasps (''[[Vespula vulgaris]]'') eat adult sawflies and the larvae, as do lizards and frogs.<ref>{{cite journal |last1=Müller |first1=Caroline |last2=Brakefield |first2=P.M.|title=Analysis of a chemical defense in sawfly larvae: easy bleeding targets predatory wasps in late summer|journal=Journal of Chemical Ecology |date=2003|volume=29 |issue=12 |pages=2683–2694 |doi=10.1023/B:JOEC.0000008012.73092.01|pmid=14969355|bibcode=2003JCEco..29.2683M |s2cid=23689052 |issn=1573-1561}}</ref><ref>{{cite journal|last1=Petre|first1=C.-A.|last2=Detrain|first2=C.|last3=Boevé|first3=J.-L.|title=Anti-predator defence mechanisms in sawfly larvae of ''Arge'' (Hymenoptera, Argidae)|journal=Journal of Insect Physiology |date=2007 |volume=53|issue=7|pages=668–675 |doi=10.1016/j.jinsphys.2007.04.007|pmid=17540402|bibcode=2007JInsP..53..668P |hdl=2268/151323|url=http://orbi.ulg.ac.be/handle/2268/151323|hdl-access=free}}</ref> [[Pardalote]]s, [[honeyeater]]s and [[fantail]]s (''Rhipidura'') occasionally consume laid eggs, and several species of beetle larvae prey on the pupae.<ref name=SA1992/>

The larvae have several [[anti-predator adaptations]]. While adults are unable to sting, the larvae of species such as the [[spitfire sawfly]] regurgitate a distasteful irritating liquid, which makes predators such as ants avoid the larvae.<ref name=AusMus/><ref Name=PIRSA>{{cite web |url=http://www.pir.sa.gov.au/forestry/publications_index/spitfires_-_defoliating_sawflies |title=Spitfires - Defoliating Sawflies |access-date=2010-04-10 |last=Phillips |first=Charlma |date=December 1992 |publisher=PIRSA |url-status=dead |archive-url=https://web.archive.org/web/20091106172745/http://www.pir.sa.gov.au/forestry/publications_index/spitfires_-_defoliating_sawflies |archive-date=6 November 2009 |df=dmy }}</ref> In some species, the larvae cluster together, reducing their chances of being killed, and in some cases form together with their heads pointing outwards or tap their abdomens up and down.<ref name=SA1992>{{cite web |last1=Phillips |first1=C. |title=Spitfires – Defoliating Sawflies |url=http://pir.sa.gov.au/__data/assets/pdf_file/0013/234040/Number_8_Spitfires_-_defoliating_sawflies.pdf |work=Department of Primary Industries and Resources |publisher=Government of South Australia |access-date=11 August 2015 |date=1992 |archive-date=6 April 2015 |archive-url=https://web.archive.org/web/20150406151250/http://www.pir.sa.gov.au/__data/assets/pdf_file/0013/234040/Number_8_Spitfires_-_defoliating_sawflies.pdf |url-status=dead }}</ref><ref>{{cite book |last1=Hairston |first1=N.G. |title=Ecological Experiments: Purpose, Design and Execution |date=1989 |publisher=Cambridge University Press |location=Cambridge, Massachusetts |isbn=978-0-521-34692-4 |page=96}}</ref> Some adults bear black and yellow markings that mimic wasps.<ref name="Burton_Burton_2002"/>

===Parasites===
[[File:Sawfly parasitic wasp (Dahlbominus fuscipennis).jpg|thumb|left|[[Parasitoid]]al [[Eulophidae|eulophid wasps]] ([[:sv:Dahlbominus fuscipennis|''Dahlbominus fuscipennis'' (sv)]]) emerging from a sawfly cocoon]]

Sawflies are hosts to many parasitoids, most of which are parasitic Hymenoptera; more than 40 species are known to attack them. However, information regarding these species is minimal, and fewer than 10 of these species actually cause a significant impact on sawfly populations.{{sfn|Capinera|2008|p=1827}} Many of these species attack their hosts in the grass or in other parasitoids.{{clarify|what does this mean? In which grass? If they are hyper parasitoids then surely the parasitoid is their host?|date=November 2017}} Well known and important parasitoids include [[Braconidae]], [[Eulophidae]] and [[Ichneumonidae]]. Braconid wasps attack sawflies in many regions throughout the world, in which they are ectoparasitoids, meaning that the larvae live and feed outside of the hosts body; braconids have more of an impact on sawfly populations in the New World than they do in the Old World, possibly because there are no ichneumonid parasitoids in North America. Some braconid wasps that attack sawflies include ''[[Bracon cephi]]'', ''[[Bracon lisogaster|B. lisogaster]]'', ''[[Bracon terabeila|B. terabeila]]'' and ''[[Heteropilus cephi]]''.{{sfn|Capinera|2008|p=1827}}<ref>{{cite book|author1=Alberta Agriculture|title=Guide to Crop Protection in Alberta|date=1988|publisher=University of Alberta|location=Alberta|volume=2|page=[https://archive.org/details/guidetocropprote02albe/page/73 73]|url=https://archive.org/details/guidetocropprote02albe}}</ref><ref>{{cite journal |last1=Nelson |first1=W.A. |last2=Farstad |first2=C.W. |title=Biology of ''Bracon cephi'' (Gahan) (Hymenoptera: Braconidae), an important native parasite of the wheat stem sawfly, ''Cephus cinctus'' Nort. (Hymenoptera: Cephidae), in Western Canada|journal=The Canadian Entomologist |date=2012 |volume=85 |issue=3 |pages=103–107 |doi=10.4039/Ent85103-3|s2cid=85132364 }}</ref> Female braconids locate sawfly larvae through the vibrations they produce when feeding, followed by inserting the ovipostior and paralysing the larva before laying eggs inside the host. These eggs hatch inside the larva within a few days, where they feed on the host. The entire host's body may be consumed by the braconid larvae, except for the head capsule and [[epidermis]]. The larvae complete their development within two or three weeks.{{sfn|Capinera|2008|p=1827}}

Ten species of wasps in the family Ichneumonidae attack sawfly populations, although these species are usually rare. The most important parasitoids in this family are species in the genus ''Collyria''. Unlike braconids, the larvae are endoparasitoids, meaning that the larvae live and feed inside the hosts body.{{sfn|Capinera|2008|p=1827}} One well known ichneumonid is ''[[Collyria coxator]]'', which is a dominant parasitoid of ''C. pygmaeus''. Recorded parasitism rates in Europe are between 20–76%, and as many as eight eggs can be found in a single larva, but only one ''Collyria'' individual will emerge from its host. The larva may remain inside of their host until spring, where it emerges and pupates.{{sfn|Capinera|2008|p=1827}}

Several species in the family Eulophidae attack sawflies, although their impact is low. Two species in the genus ''[[Pediobius]]'' have been studied; the two species are internal larval parasitoids and have only been found in the northern hemisphere. Parasitism of sawflies by eulophids in grass exceeds 50%, but only 5% in wheat. It is unknown as to why the attack rate in wheat is low.{{sfn|Capinera|2008|p=1827–1828}} Furthermore, some fungal and bacterial diseases are known to infect eggs and pupa in warm wet weather.<ref name=SA1992/>

Outbreaks of certain sawfly species, such as ''[[Diprion polytomum]]'', have led scientists to investigate and possibly collect their natural enemies to control them. Parasites of ''D. polytomum'' have been extensively investigated, showing that 31 species of hymenopterous and dipterous parasites attack it. These parasites have been used in successful biological control against pest sawflies, including ''Cephus cinctus'' throughout the 1930s and 1950s and ''C. pygmaeus'' in the 1930s and 1940s.{{sfn|Capinera|2008|p=1828}}<ref>{{cite journal |last1=Morris |first1=K.R.S. |last2=Cameron |first2=E. |last3=Jepson |first3=W.F. |title=The insect parasites of the spruce sawfly (''Diprion polytomum'', Htg.) in Europe |journal=Bulletin of Entomological Research |date=1937 |volume=28 |issue=3 |pages=341–393 |doi=10.1017/S0007485300038840}}</ref>

===Life cycle and reproduction===
[[File:Lophyre mâle sortant de son cocon-page0001.jpg|thumb|upright|Adult male newly emerged from its cocoon]]

Like all other hymenopteran insects, sawflies go through a [[Metamorphosis|complete metamorphosis]] with four distinct life stages – egg, larva, pupa and adult.<ref>{{cite book|last1=Hartman|first1=J.R.|last2=Pirone|first2=T.P.|last3=Sall|first3=M.A.|title=Pirone's Tree Maintenance|url=https://archive.org/details/pironestreemaint00hart|url-access=limited|date=2000|publisher=Oxford University Press|location=New York, New York|isbn=978-0-19-802817-8|pages=[https://archive.org/details/pironestreemaint00hart/page/n245 235]|edition=7th}}</ref> Many species are [[Parthenogenesis|parthenogenetic]], meaning that females do not need fertilization to create viable eggs. Unfertilized eggs develop as male, while fertilized eggs develop into females ([[arrhenotoky]]). The lifespan of an individual sawfly is two months to two years, though the adult life stage is often very short (approximately 7 – 9 days), only long enough for the females to lay their eggs.<ref name="Burton_Burton_2002">{{cite book|last1=Burton|first1=M.|last2=Burton|first2=R.|title=International Wildlife Encyclopedia|date=2002|publisher=Marshall Cavendish|location=Tarrytown, New York|isbn=978-0-7614-7282-7|pages=[https://archive.org/details/internationalwil16burt0/page/2240 2240]–2241|volume=16|edition=3rd|url-access=registration|url=https://archive.org/details/internationalwil16burt0}}</ref><ref name=SA1992/><ref>{{cite journal|last1=Müller|first1=C.|last2=Barker|first2=A.|last3=Boevé|first3=J.-L.|last4=De Jong|first4=P.W.|last5=De Vos|first5=H.|last6=Brakefield|first6=P.M.|title=Phylogeography of two parthenogenetic sawfly species (Hymenoptera: Tenthredinidae): relationship of population genetic differentiation to host plant distribution|journal=Biological Journal of the Linnean Society|date=2004|volume=83|issue=2|pages=219–227|doi=10.1111/j.1095-8312.2004.00383.x|doi-access=free}}</ref> The female uses its ovipositor to drill into plant material to lay her eggs (though the family [[Orussoidea]] lay their eggs in other insects). Plant-eating sawflies most commonly are associated with leafy material but some specialize on wood, and the ovipositors of these species (such as the family [[horntail|Siricidae]]) are specially adapted for the task of drilling through bark. Once the incision has been made, the female will lay as many as 30 to 90 eggs. Females avoid the shade when laying their eggs because the larvae develop much slower and may not even survive, and they may not also survive if they are laid on immature and glaucous leaves. Hence, female sawflies search for young adult leaves to lay their eggs on.<ref name="Burton_Burton_2002"/><ref name=SA1992/>

These eggs hatch in two to eight weeks, but such duration varies by species and also by temperature. Until the eggs have hatched, some species such as the small brown sawfly will remain with them and protects the eggs by buzzing loudly and beating her wings to deter predators. There are six larval stages that sawflies go through, lasting 2 – 4 months, but this also depends on the species. When fully grown, the larvae emerge from the trees en masse and burrow themselves into the soil to pupate. During their time outside, the larvae may link up to form a large colony if many other individuals are present. They gather in large groups during the day which gives them protection from potential enemies, and during the night they disperse to feed. The emergence of adults takes awhile, with some emerging anywhere between a couple months to 2 years. Some will reach the ground to form pupal chambers, but others may spin a cocoon attached to a leaf. Larvae that feed on wood will pupate in the tunnels they have constructed. In one species, the [[Phyllotoma aceris|jumping-disc sawfly]] (''Phyllotoma aceris'') forms a cocoon which can act like a parachute. The larvae live in sycamore trees and do not damage the upper or lower cuticles of leaves that they feed on. When fully developed, they cut small [[perforation]]s in the upper cuticle to form a circle. After this, they weave a silk [[hammock]]s within the circle; this silk hammock never touches the lower cuticle. Once inside, the upper-cuticle's disc separates and descends towards the surface with the larvae attaching themselves to the hammock. Once they reach the round, the larvae work their way into a sheltered area by jerking their discs along.<ref name="Burton_Burton_2002"/><ref name=SA1992/>

The majority of sawfly species produce a single generation per year, but others may only have one generation every two years. Most sawflies are also female, making males rare.<ref name=SA1992/>

<gallery mode="packed" caption="Life cycle of the sawfly ''[[Cladius difformis]]'', the bristly rose slug">
File:Cladius difformis larva.jpg|Larva
File:Cladius difformis pupa dorsal.jpg|Pupa, dorsal view
File:Cladius difformis pupa ventral.jpg|Pupa, ventral view
File:Cladius difformis female.jpg|Female
File:Cladius difformis male.jpg|Male
</gallery>

==Relationship with humans==
[[File:Diprionpini.jpg|thumb|left|The pine sawfly ''[[Diprion pini]]'' is a serious pest of [[forestry]].]]
[[File:Yellow Flag Iris Sawfly (Rhadinoceraea micans) showing damage to plant.JPG|thumb|upright|[[Caterpillar]]-like larvae of [[Iris sawfly]]  on [[Iris pseudacorus|yellow flag]], showing damage to [[host (biology)|host]] plant]]

Sawflies are major economic pests of [[forestry]]. Species in the Diprionidae, such as the pine sawflies, ''[[Diprion pini]]'' and ''[[Neodiprion sertifer]]'', cause serious damage to [[pine]]s in regions such as Scandinavia. ''D. pini'' larvae defoliated {{convert|500,000|ha|acre}} in the largest outbreak in Finland, between 1998 and 2001. Up to 75% of the trees may die after such outbreaks, as ''D. pini'' can remove all the leaves late in the growing season, leaving the trees too weak to survive the winter.<ref>{{cite web |url=http://sciencenordic.com/content/common-pine-sawfly-%E2%80%93-troublesome-relative |title=The common pine sawfly – a troublesome relative |author=Krokene, Paal |date=6 December 2014 |publisher=Science Nordic |access-date=28 November 2016 |archive-date=29 November 2016 |archive-url=https://web.archive.org/web/20161129021237/http://sciencenordic.com/content/common-pine-sawfly-%E2%80%93-troublesome-relative |url-status=dead }}</ref> Little damage to trees only occurs when the tree is large or when there is minimal presence of larvae. ''Eucalyptus'' trees can regenerate quickly from damage inflicted by the larvae; however, they can be substantially damaged from outbreaks, especially if they are young. The trees can be defoliated completely and may cause "dieback", stunting or even death.<ref name=SA1992/>

Sawflies are serious pests in [[horticulture]]. Different species prefer different host plants, often being specific to a family or genus of hosts. For example, [[Iris sawfly]] larvae, emerging in summer, can quickly defoliate species of ''[[Iris (plant)|Iris]]'' including the [[Iris pseudacorus|yellow flag]] and other freshwater species.<ref>{{cite web |title=Iris sawfly |url=https://www.rhs.org.uk/advice/profile?pid=908 |publisher=Royal Horticultural Society |access-date=28 November 2016}}</ref> Similarly the rose sawflies, ''[[Arge pagana]]'' and ''[[Arge ochropus|A. ochropus]]'', defoliate rose bushes.<ref>{{cite web |title=Large rose sawfly |url=https://www.rhs.org.uk/advice/profile?PID=196 |publisher=Royal Horticultural Society |access-date=28 November 2016}}</ref>

The giant woodwasp or horntail, ''[[Urocerus gigas]]'', has a long ovipositor, which with its black and yellow colouration make it a good mimic of a [[hornet]]. Despite the alarming appearance, the insect cannot sting.<ref>{{cite web |title=Great Wood Wasps |url=http://www.uksafari.com/woodwasp.htm |publisher=UK Safari |access-date=28 November 2016}}</ref> The eggs are laid in the wood of [[conifer]]s such as [[Douglas fir]], pine, [[spruce]], and [[larch]]. The larvae eat tunnels in the wood, causing economic damage.<ref>{{cite web |title=Giant Woodwasp |url=http://massnrc.org/pests/pestFAQsheets/giant%20woodwasp.htm |publisher=Massachusetts Introduced Pests Outreach Project |access-date=28 November 2016}}</ref>

Alternative measures to control sawflies can be taken. Small-scale, mechanical methods include visually confirming larval presence on a plant and subsequently removing them, either by pruning damaged leaves or removing the larvae from the leaves they are on. Larvae typically try to remain hidden on the underside of foliage. Upon removing larvae and/or the affected leaves from plants, they may be dispatched by squishing, or, alternatively, the cut leaves with larvae still attached may be fed to birds; if larger animals do not prey upon them, other insects will. However, this is not practical or useful for some, thus the larvae can be quickly dispatched by simply dropping foliage into a vessel of plain or saltwater, diluted hydrogen peroxide or isopropyl alcohol, insecticidal soap, or other garden chemical. In large-scale, industrial settings, where beneficial insect predators can also be used to eliminate larvae, as well as parasites, which have both been previously used in control programs.<ref name=SA1992/>{{sfn|Capinera|2008|p=1828}} Small trees can be sprayed with a number of chemicals, including [[Malathion|maldison]], [[dimethoate]], [[carbaryl]], [[imidacloprid]], etc., if removing larvae from trees is not effective enough.<ref name=SA1992/>

== References ==
{{Reflist}}

===Bibliography===
* {{cite book |last1=Capinera|first1=J.L.|title=Encyclopedia of Entomology|url=https://books.google.com/books?id=i9ITMiiohVQC|date=2008|publisher=Springer Science & Business Media|location=Dordrecht, Netherlands|isbn=978-1-4020-6242-1|edition=2nd}}
* {{cite book|last1=Goulet|first1=H.|last2=Huber|first2=J.T.|title=Hymenoptera of the World: An Identification guide to families|date=1993|publisher=Agriculture Canada|location=Ottawa, Ontario|isbn=978-0-660-14933-2|url=http://www.esc-sec.ca/aafcmonographs/hymenoptera_of_the_world.pdf|url-status=dead|archive-url=https://web.archive.org/web/20160305012733/http://www.esc-sec.ca/aafcmonographs/hymenoptera_of_the_world.pdf|archive-date=5 March 2016|df=dmy-all}}
* {{cite book |last1=Ross |first1=H.H.|title=A Generic Classification of the Nearctic Sawflies (Hymenoptera, Symphyta)|date=1937 |publisher=University of Illinois |location=Urbana, Illinois|url=https://archive.org/details/genericclassific15ross |doi=10.5962/bhl.title.50339|hdl=2142/27324}}

==Further reading==
*{{cite book|last1=Blank|first1=S.M.|last2=Schmidt|first2=S.|last3=Taeger|first3=A.|title=Recent Sawfly Research Synthesis and Prospects|url=https://books.google.com/books?id=xR84NAAACAAJ|date=2006|publisher=Goecke und Evers|location=Keltern, Germany|isbn=978-3-937783-19-2}}
*{{cite book|last1=Schedl|first1=Wolfgang.|title=Hymenoptera, Unterordnung Symphyta: Pflanzenwespen|date=2016|publisher=Walter de Gruyter|isbn=978-3-11-085790-0|url=https://books.google.com/books?id=Pf-XcKvIhdkC}}
*{{cite book|last1=Smith|first1=D.R.|title=Nearctic Sawflies I. Blennocampinae: Adults and Larvae (Hymenoptera: Tenthredinidae)|date=1969|publisher=US Department of Agriculture|location=Washington, D.C.|url=https://books.google.com/books?id=30kYuOzB6NgC|format=Technical Bulletin 1397}}
*{{cite book|last1=Smith|first1=D.R.|title=Nearctic Sawflies II. Selandriinae: Adults and Larvae (Hymenoptera: Tenthredinidae)|date=1969|publisher=US Department of Agriculture|location=Washington, D.C.|url=https://books.google.com/books?id=NPWmdYy0ozgC|format=Technical Bulletin 1398}}
*{{cite book|last1=Smith|first1=D.R.|title=Nearctic Sawflies III. Heterarthrinae: Adults and Larvae (Hymenoptera: Tenthredinidae)|date=1971|publisher=US Department of Agriculture|location=Washington, D.C.|url=https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=CAT87201390&cotent=PDF|format=Technical Bulletin 1420|access-date=29 December 2018|archive-date=21 October 2020|archive-url=https://web.archive.org/web/20201021111239/https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=CAT87201390&cotent=PDF|url-status=dead}}
*{{cite book|last1=Smith|first1=D.R.|title=Nearctic Sawflies IV. Allantinae: Adults and Larvae (Hymenoptera: Tenthredinidae)|date=1979|publisher=US Department of Agriculture|location=Washington, D.C.|url=https://www.researchgate.net/publication/260438027|format=Technical Bulletin 1595}}
*{{cite book|last1=Wagner|first1=M.R.|last2=Raffa|first2=K.F.|title=Sawfly Life History Adaptations to Woody Plants|date=1993|publisher=Academic Press|location=San Diego, California|isbn=978-0-12-730030-6|url=https://books.google.com/books?id=U1QgAQAAMAAJ}}

==External links==
*{{Wikispecies-inline|Symphyta}}
*{{Commons category-inline|Symphyta}}

===General===
*[https://www.britannica.com/animal/Symphyta Symphyta: Encyclopædia Britannica]
*[https://web.archive.org/web/20090716204238/http://www.csiro.au/resources/Sawfly-Factsheet.html Sawflies: a close relative of wasps] at CSIRO
*[http://bugguide.net/node/view/112 Symphyta" - Sawflies, Horntails, and Wood Wasps] at BugGuide

===Taxonomy===
*[http://www.chrysis.net/chrysis/intro/hym_tree.htm Taxonomy of Hymenoptera] – Chrysis.net
*[http://sdei.senckenberg.de/ecatsym ECatSym - Electronic World Catalog of Symphyta (Insecta, Hymenoptera)] – Digital Entomological Information
*[https://bdj.pensoft.net/articles.php?id=1168 Checklist of British and Irish Hymenoptera - Sawflies, ‘Symphyta’] ''Biodiversity Data Journal 2'': e1168

{{Hymenoptera|1}}
{{Taxonbar|from=Q615290}}
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[[Category:Sawflies| ]]
[[Category:Insect pests of ornamental plants]]
[[Category:Insect pests of temperate forests]]
[[Category:Extant Triassic first appearances]]
[[Category:Taxa named by Carl Eduard Adolph Gerstaecker]]
[[Category:Paraphyletic groups]]
[[Category:Articles containing video clips]]