Editing Hymenoptera

{{short description|Order of insects comprising sawflies, wasps, bees, and ants}}
{{Automatic taxobox
| fossil_range = [[Triassic]]–[[Holocene|Present]] {{fossilrange|235|0|ref=<ref name="Ronquist2012">{{cite journal | last1=Ronquist | first1=Fredrik | last2=Klopfstein | first2=Seraina | last3=Vilhelmsen | first3=Lars | last4=Schulmeister | first4=Susanne | last5=Murray | first5=Debra L. | last6=Rasnitsyn | first6=Alexandr P. | date=December 2012 | title=A Total-Evidence Approach to Dating with Fossils, Applied to the Early Radiation of the Hymenoptera | journal=Systematic Biology | volume=61 | issue=6 | pages=973–999 | doi=10.1093/sysbio/sys058 | pmid=22723471 | pmc=3478566}}</ref>}}
| image = Hymenoptera.jpg
| image_upright = 1.2
| image_caption = Hymenopterans from different families; Clockwise from top-left: [[Red imported fire ant]] (Formicidae), ''[[Vespula vulgaris]]'' (Vespidae), ''[[Tenthredopsis|Tenthredopsis sordida]]'' (Tenthredinidae), and [[Western honey bee]] (Apidae)
| display_parents = 2
| taxon = Hymenoptera
| authority = [[Linnaeus]], [[10th edition of Systema Naturae|1758]]
| subdivision_ranks = Suborders
| subdivision = *[[Symphyta]] (sawflies) ([[paraphyletic]])
*[[Apocrita]] (wasps, bees and ants)
}}

''' Hymenoptera''' is a large [[order (biology)|order]] of [[insect]]s, comprising the [[sawflies]], [[wasp]]s, [[bee]]s, and [[ant]]s. Over 150,000 living species of Hymenoptera have been described,<ref name="Mayhew2007">{{cite journal |last1=Mayhew |first1=Peter J. |title=Why are there so many insect species? Perspectives from fossils and phylogenies |journal=Biological Reviews|volume=82|issue=3 |year=2007 |pages=425–454 |doi=10.1111/j.1469-185X.2007.00018.x |pmid=17624962|s2cid=9356614}}</ref><ref name="JankeKlopfstein2013">{{cite journal |last1=Janke |first1=Axel |last2=Klopfstein |first2=Seraina |last3=Vilhelmsen |first3=Lars |last4=Heraty |first4=John M. |last5=Sharkey |first5=Michael |last6=Ronquist |first6=Fredrik |title=The Hymenopteran Tree of Life: Evidence from Protein-Coding Genes and Objectively Aligned Ribosomal Data |journal=PLOS ONE |volume=8 |issue=8 |year=2013 |pages=e69344 |doi=10.1371/journal.pone.0069344 |pmid=23936325 |pmc=3732274 |bibcode=2013PLoSO...869344K|doi-access=free }}</ref> in addition to over 2,000 extinct ones.<ref name="Aguiar2013">{{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. | year=2013 | title=Order Hymenoptera Linnaeus, 1758. In: Zhang, Z.-Q. (Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013) | journal=Zootaxa | volume=3703 | pages=1–82 | pmid=26146682 | doi=10.11646/zootaxa.3703.1.12| doi-access=free }}</ref> Many of the species are [[Parasitoid wasp|parasitic]]. 
Females typically have a special [[ovipositor]] for inserting eggs into hosts or places that are otherwise inaccessible. This ovipositor is often modified into a [[stinger]]. The young develop through [[holometabolism]] (complete [[metamorphosis]])—that is, they have a wormlike larval stage and an inactive pupal stage before they reach adulthood.

==Etymology==
The name Hymenoptera refers to the wings of the insects, but the original derivation is ambiguous.<ref name=Grissel10>{{Cite book |title=Bees, Wasps, and Ants: The Indispensable Role of Hymenoptera in Gardens |url=https://archive.org/details/isbn_9780881929881 |url-access=registration |publisher=Timber Press |last=Grissell |first=Eric |year=2010|isbn=9780881929881 }}</ref>{{rp|42}} All references agree that the derivation involves the [[Ancient Greek]] [[wikt:πτερόν|πτερόν]] (''pteron'') for wing.<ref name=EB1911>{{Cite EB1911 |wstitle=Hymenoptera |volume=14 |page=177 |first=George Herbert |last=Carpenter |author-link=George Herbert Carpenter}}</ref> The Ancient Greek [[wikt:ὑμήν|ὑμήν]] (''hymen'') for membrane provides a plausible [[etymology]] for the term because species in this order have membranous wings.<ref name=EB1911/> However, a key characteristic of this order is that the [[hindwings]] are connected to the [[forewings]] by a series of [[hamuli|hooks]]. Thus, another plausible etymology involves [[Hymen (god)|Hymen]], the Ancient Greek god of marriage, as these insects have "married" wings in flight.{{Citation needed|date=May 2025}} Another suggestion for the inclusion of Hymen is the myth of [[Melissa (mythology)|Melissa]], a nymph with a prominent role at the wedding of Zeus.{{Citation needed|date=November 2023}}

==Evolution==
Molecular analysis finds that Hymenoptera is the earliest branching group of [[Holometabola]].<ref name=Kjer>{{Cite journal |last1=Kjer |first1=Karl M. |last2=Simon |first2=Chris|author2-link=Chris Simon (biologist) |last3=Yavorskaya |first3=Margarita |last4=Beutel |first4=Rolf G. |date=2016 |title=Progress, pitfalls and parallel universes: a history of insect phylogenetics |journal=Journal of the Royal Society Interface |volume=13 |issue=121 |page=121 |doi=10.1098/rsif.2016.0363 |pmid=27558853 |name-list-style=amp |pmc=5014063 }}</ref>

{{clade
|label1=[[Holometabola]]
|1={{clade
   |label1=[[Hymenopterida]]
   |1='''Hymenoptera''' (sawflies, wasps) [[File:European wasp white bg.jpg|70px]]
   |label2=[[Aparaglossata]]
   |2={{clade
      |label1=[[Neuropteroidea]]      
      |1={{clade
         |label1=[[Coleopterida]]
         |1={{clade
            |1=[[Coleoptera]] (beetles) [[File:Pseudacrossus przewalskyi (Reitter, 1887).jpg|50px]]
            |2=[[Strepsiptera]] (twisted-wing parasites) [[File:Elenchus koebelei.jpg|70px]]
            }}
         |label2=[[Neuropterida]]
         |2={{clade
            |1=[[Raphidioptera]] (snakeflies) [[File:Raphidia icon.png|70px]]
            |label2=
            |2={{clade
               |1=[[Megaloptera]] (alderflies and allies) [[File:Corydalus cornutus illustration (rotated).png|70px]]
               |2=[[Neuroptera]] (Lacewings and allies) [[File:Osmylus_(white_background).jpg|70px]]
               }}
            }}
         }}
      |label2=[[Panorpida]]
      |2={{clade
         |label1=[[Amphiesmenoptera]]
         |1={{clade
            |1=[[Lepidoptera]] (butterflies, moths) [[File:Arctia villica SLU.JPG|70px]]
            |2=[[Trichoptera]] (caddisflies) [[File:RHYACOPHILA DORSALIS Male Pont Forge de Sailly Watigny 02 MHNT.jpg|70px]] 
            }}
         |label2=Antliophora
         |2={{clade 
            |1=[[Diptera]] [[File:Common house fly, Musca domestica.jpg|70px]] 
            |2={{clade
               |1=[[Mecoptera]] (scorpionflies)  [[File:Scorpionfly (white background).jpg|70px]]
               |2=[[Siphonaptera]] (fleas) [[File:Pulex irritans female ZSM (white background).jpg|40px]]
               }}
            }}
         }}
      }}
   }}
}}

Hymenoptera originated in the [[Triassic]], with the oldest fossils belonging to the family [[Xyelidae]]. Social hymenopterans appeared during the [[Cretaceous]].<ref name=IIBD>
{{cite book |author=Howell, H.V. |author2=Doyen, J.T. |author3=Purcell, A.H. |year=1998 |title=Introduction to Insect Biology and Diversity |edition=2nd |publisher=Oxford University Press |page=320 |isbn=978-0-19-510033-4}}</ref> The evolution of this group has been intensively studied by [[Alex Rasnitsyn]], [[Michael S. Engel]], and others.<ref>{{Cite journal |last1=Peters |first1=Ralph S. |last2=Krogmann |first2=Lars |last3=Mayer |first3=Christoph |last4=Donath |first4=Alexander |last5=Gunkel |first5=Simon |last6=Meusemann |first6=Karen |last7=Kozlov |first7=Alexey |last8=Podsiadlowski |first8=Lars |last9=Petersen |first9=Malte |date=April 2017 |title=Evolutionary History of the Hymenoptera |journal=Current Biology |volume=27 |issue=7 |pages=1013–1018 |doi=10.1016/j.cub.2017.01.027|pmid=28343967 |doi-access=free|bibcode=2017CBio...27.1013P |hdl=2434/801122 |hdl-access=free }}</ref>

{{anchor|Unicalcarida}}
Phylogenetic relationships within the Hymenoptera, based on both morphology and molecular data, have been intensively studied since 2000.<ref name=Blaimer2023>{{Cite Q|Q117865968|author1-first=Bonnie B.|author1-last=Blaimer|author2-first=Bernardo F.|author2-last=Santos|author3-first=Astrid|author3-last=Cruaud}}</ref> In 2023, a molecular study<ref name=Blaimer2023/> based on the analysis of [[Ultra-conserved element|ultra-conserved elements]] confirmed many previous findings and produced a relatively robust phylogeny of the whole Order. Basal superfamilies are shown in the cladogram below.

{{cladogram|title=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=[[Tenthredinoidea]] [[File:Endelomyia rosae.jpg|50px]]  |barbegin1=red 
   |2={{clade
      |1=[[Xyeloidea]]  ([[Triassic]]-present) [[File:Xyelapusilla.jpg|50px]] |bar1=red 
      |2={{clade
         |1=[[Pamphilioidea]] [[File:Cephalcia clarkii.png|50px]] |bar1=red
         |label2=[[Unicalcarida]]
         |2={{clade
            |1={{clade
               |1=[[Siricoidea]] (horntails or wood wasps) [[File:Hymenoptera Vielfalt Horntail.jpg|55px]] |bar1=red
               |2=[[Xiphydrioidea]] (wood wasps)  [[File:Xiphydria prolongata crop.jpg|50px]] |bar2=red
               }}
            |2={{clade
               |1=[[Cephoidea]] (stem sawflies) [[File:Hartigia linearis.jpg|50px]] |bar1=red
                  |label2=''parasitism'' 
               |2={{clade
                     |1=[[Orussoidea]]  ([[parasitic]] wood wasps) [[File:Orussus coronatus.jpg|45px]]|barend1=red 
                     |label2= "wasp waist"
                     |sublabel2=200mya
                     |2=[[Apocrita]] ([[ant]]s, [[bee]]s, [[wasp]]s)  [[File:Specimen of Podalonia tydei (Le Guillou, 1841).jpg|60px]]
                     }}
                  }}
               }}
            }}
         }}
      }}
   }}
}}
}}{{-}}

==Anatomy==
[[File:Bombus muscorum1.jpg|thumb|''[[Bombus muscorum]]'' drinking nectar with its long proboscis]]
Hymenopterans range in size from very small to large insects, and usually have two pairs of wings. Their [[insect mouthparts|mouthparts]] are adapted for chewing, with well-developed [[Mandible (insect mouthpart)|mandible]]s (ectognathous mouthparts). Many species have further developed the mouthparts into a lengthy [[proboscis]], with which they can drink liquids, such as [[nectar]]. They have large [[compound eyes]], and typically three simple eyes, [[ocelli]].

The forward margin of the hind wing bears a number of hooked bristles, or "[[hamuli]]", which lock onto the fore wing, keeping them held together. The smaller species may have only two or three hamuli on each side, but the largest wasps may have a considerable number, keeping the wings gripped together especially tightly. Hymenopteran wings have relatively few veins compared with many other insects, especially in the smaller species.

In the more ancestral hymenopterans, the [[ovipositor]] is blade-like, and has evolved for slicing plant tissues. In the majority, however, it is modified for piercing, and, in some cases, is several times the length of the body. In some species, the ovipositor has become modified as a [[stinger]], and the [[egg (biology)|eggs]] are laid from the base of the structure, rather than from the tip, which is used only to inject [[venom]]. The sting is typically used to immobilize prey, but in some wasps and bees may be used in defense.<ref name=IIBD/>

Hymenopteran larvae typically have a distinct head region, three thoracic segments, and usually nine or 10 abdominal segments. In the suborder [[Symphyta]], the [[eruciform]] larvae resemble [[caterpillar]]s in appearance, and like them, typically feed on leaves. They have large chewing mandibles, three pairs of thoracic limbs, and, in most cases, six or eight abdominal [[proleg]]s. Unlike caterpillars, however, the prolegs have no grasping spines, and the antennae are reduced to mere stubs. Symphytan larvae that are wood borers or stem borers have no abdominal legs and the thoracic legs are smaller than those of non-borers.

With rare exceptions, larvae of the suborder [[Apocrita]] have no legs and are [[maggot]]like in form, and are adapted to life in a protected environment. This may be the body of a host organism, or a cell in a nest, where the adults will care for the larva. In parasitic forms, the head is often greatly reduced and partially withdrawn into the prothorax (anterior part of the thorax). Sense organs appear to be poorly developed, with no ocelli, very small or absent antennae, and toothlike, sicklelike, or spinelike mandibles. They are also unable to defecate until they reach adulthood due to having an incomplete digestive tract (a blind sac), presumably to avoid contaminating their environment.<ref name=IIBD/> The larvae of stinging forms ([[Aculeata]]) generally have 10 pairs of spiracles, or breathing pores, whereas parasitic forms usually have nine pairs present.<ref name="Missouri2007">{{cite book |last=Hunt |first=James H. |title=The Evolution of Social Wasps |url=https://books.google.com/books?id=bFMoSxCVSVIC&pg=PA12 |date=2007 |publisher=Oxford University Press, USA |isbn=978-0-19-804207-5 |page=12}}</ref>

==Reproduction==

===Sex determination===
{{main|Haplodiploid sex-determination system}}

Among most or all hymenopterans, sex is [[sex-determination system|determined]] by the number of [[chromosome]]s an individual possesses.<ref name=Cowan2004>{{cite journal |last1=Cowan |first1=David P. Cowan |last2=Stahlhut |first2=Julie K. | title=Functionally reproductive diploid and haploid males in an inbreeding hymenopteran with complementary sex determination | journal=PNAS | volume=101 | issue=28 | pages=10374–10379 | date=13 July 2004 | doi=10.1073/pnas.0402481101 | pmid=15232002 | pmc=478579 |bibcode=2004PNAS..10110374C|doi-access=free }}</ref> Fertilized eggs get two sets of chromosomes (one from each parent's respective [[gamete]]s) and develop into [[diploid]] females, while unfertilized eggs only contain one set (from the mother) and develop into [[haploid]] males. The act of fertilization is under the voluntary control of the egg-laying female, giving her control of the sex of her offspring.<ref name=IIBD/> This phenomenon is called [[haplodiploidy]].

However, the actual genetic mechanisms of haplodiploid sex determination may be more complex than simple chromosome number. In many Hymenoptera, sex is determined by a single gene locus with many alleles.<ref name=Cowan2004/> In these species, haploids are male and diploids heterozygous at the sex locus are female, but occasionally a diploid will be homozygous at the sex locus and develop as a male, instead. This is especially likely to occur in an individual whose parents were [[siblings]] or other close relatives. Diploid males are known to be produced by inbreeding in many ant, bee, and wasp species. Diploid biparental males are usually sterile but a few species that have fertile diploid males are known.<ref>{{Cite journal | last1=Elias | first1=J. | last2=Mazzi | first2=D. | last3=Dorn | first3=S. | editor1-last=Bilde | editor1-first=Trine | title=No Need to Discriminate? Reproductive Diploid Males in a Parasitoid with Complementary Sex Determination | doi=10.1371/journal.pone.0006024 | journal=PLOS ONE | volume=4 | issue=6 | pages=e6024 | year=2009 | pmid=19551142| pmc =2696080 | bibcode=2009PLoSO...4.6024E| doi-access=free }}</ref>

One consequence of haplodiploidy is that females on average have more genes in common with their sisters than they do with their daughters. Because of this, cooperation among kindred females may be unusually advantageous and has been hypothesized to contribute to the multiple origins of [[eusociality]] within this order.<ref name=IIBD/><ref>{{Cite journal |last1=Quiñones |first1=Andrés E. |last2=Pen |first2=Ido |date=June 2017 |title=A unified model of Hymenopteran preadaptations that trigger the evolutionary transition to eusociality |journal=Nature Communications |volume=8 |pages=15920 |doi=10.1038/ncomms15920 |pmc=5490048 |pmid=28643786|bibcode=2017NatCo...815920Q}}</ref> In many colonies of bees, ants, and wasps, worker females will remove eggs laid by other workers due to increased relatedness to direct siblings, a phenomenon known as [[worker policing]].<ref>Davies, N.R.; Krebs, J.R.; and West, S.A. An Introduction to Behavioral Ecology. 4th ed. West Sussex: Wiley-Blackwell, 2012. pp. 387–388</ref>

Another consequence is that hymenopterans may be more resistant to the deleterious effects of [[Inbreeding depression|inbreeding]]. As males are haploid, any recessive genes will automatically be expressed, exposing them to natural selection. Thus, the [[genetic load]] of deleterious genes is purged relatively quickly.<ref>{{Cite book |title=Hymenoptera and biodiversity |first1=John |last1=LaSalle |last2=David |first2=Gauld, Ian |date=1993 |publisher=C.A.B. International |isbn=978-0851988306 |oclc=28576921 }}</ref>

===Thelytoky===
{{main|Thelytoky}}
Some hymenopterans take advantage of [[parthenogenesis]], the creation of [[embryo]]s without [[fertilization]]. [[Thelytoky]] is a particular form of parthenogenesis in which female embryos are created (without fertilisation). The form of thelytoky in hymenopterans is a kind of automixis in which two haploid products (proto-eggs) from the same [[meiosis]] fuse to form a diploid zygote. This process tends to maintain [[Zygosity|heterozygosity]] in the passage of the genome from mother to daughter. It is found in several ant species including the desert ant ''[[Cataglyphis cursor]]'',<ref name="pmid15576621">{{cite journal |last=Pearcy |first=M. |author2=Aron, S. |author3=Doums, C. |author4=Kelle, L. |title=Conditional use of sex and parthenogenesis for worker and queen production in ants |journal=Science |volume=306 |issue=5702 |pages=1780–3 |year=2004 |pmid=15576621 |doi=10.1126/science.1105453 |url=https://dipot.ulb.ac.be/dspace/bitstream/2013/18807/1/061PearcyScience04.pdf|bibcode=2004Sci...306.1780P |s2cid=37558595}}</ref> the clonal raider ant ''[[Cerapachys biroi]]'',<ref name="pmid24508170">{{cite journal |author=Oxley, P. R. |author2=Ji, L. |author3=Fetter-Pruneda, I. |author4=McKenzie, S. K. |author5=Li, C. |author6=Hu, H. |author7=Zhang, G. |author8=Kronauer, D. J. |title=The genome of the clonal raider ant Cerapachys biroi |journal=Curr. Biol. |volume=24 |issue=4 |pages=451–8 |year=2014 |pmid=24508170 |pmc=3961065 |doi=10.1016/j.cub.2014.01.018|bibcode=2014CBio...24..451O }}</ref> the predaceous ant ''[[Platythyrea punctata]]'',<ref name="Kellner">{{Cite journal |doi=10.1007/s10682-010-9382-5|title=Mechanism of facultative parthenogenesis in the ant Platythyrea punctata |journal=Evolutionary Ecology |volume=25 |pages=77–89 |year=2011 |last1=Kellner |first1=Katrin |last2=Heinze |first2=Jürgen|issue=1 |bibcode=2011EvEco..25...77K |s2cid=24645055}}</ref> and the electric ant (little fire ant) ''[[Wasmannia auropunctata]]''.<ref name=Rey>{{cite journal |author=Rey, O. |author2=Loiseau, A. |author3=Facon, B. |author4=Foucaud, J. |author5=Orivel, J. |author6=Cornuet, J. M. |author7=Robert, S. |author8=Dobigny, G. |author9=Delabie, J. H. |author10=Mariano Cdos, S. |author11=Estoup, A. |title=Meiotic recombination dramatically decreased in thelytokous queens of the little fire ant and their sexually produced workers |journal=Mol. Biol. Evol. |volume=28 |issue=9 |pages=2591–601 |year=2011 |pmid=21459760 |doi=10.1093/molbev/msr082|doi-access=free}}</ref> It also occurs in the Cape honey bee ''[[Apis mellifera capensis]]''.<ref name=Baudry>{{cite journal |author=Baudry, E. |author2=Kryger, P. |author3=Allsopp, M. |author4=Koeniger, N. |author5=Vautrin D. |author6=Mougel F. |author7=Cornuet JM. |author8=Solignac M. |title=Whole-genome scan in the lytokous-laying workers of the Cape honeybee (Apis mellifera capensis): central fusion, reduced recombination rates and centromere mapping using half-tetrad analysis |journal=Genetics |volume=167 |issue=1 |pages=243–252 |year=2004 |pmid=15166151 |pmc=1470879 |doi=10.1534/genetics.167.1.243}}</ref>

[[Oocyte]]s that undergo automixis with central fusion often have a reduced rate of [[Chromosomal crossover|crossover recombination]], which helps to maintain [[heterozygosity]] and avoid [[inbreeding depression]]. Species that display central fusion with reduced recombination include the ants ''[[Platythyrea punctata]]''<ref name="Kellner" /> and '' [[Wasmannia auropunctata]]''<ref name=Rey /> and the Cape honey bee ''Apis mellifera capensis''.<ref name=Baudry /> In ''A. m. capensis'', the recombination rate during meiosis is reduced more than tenfold.<ref name=Baudry /> In ''W. auropunctata'' the reduction is 45&nbsp;fold.<ref name=Rey />

Single queen colonies of the narrow headed ant ''[[Formica exsecta]]'' illustrate the possible deleterious effects of increased homozygosity. Colonies of this species which have more homozygous queens will age more rapidly, resulting in reduced colony survival.<ref name="pmid19127611">{{cite journal |vauthors=Haag-Liautard C, Vitikainen E, Keller L, Sundström L |title=Fitness and the level of homozygosity in a social insect |journal=J. Evol. Biol. |volume=22 |issue=1 |pages=134–142 |year=2009 |pmid=19127611 |doi=10.1111/j.1420-9101.2008.01635.x|s2cid=19566175 |url=http://doc.rero.ch/record/11248/files/haag_flh.pdf|doi-access=free }}</ref>

==Diet==
Different species of Hymenoptera show a wide range of feeding habits. The most primitive forms are typically phytophagous, feeding on flowers, pollen, foliage, or stems. Stinging wasps are predators, and will provision their larvae with immobilised prey, while bees feed on nectar and [[pollen]].

{{Main|Parasitoid wasp}}

A huge number of species are [[parasitoid]]s as larvae. The adults inject the eggs into a host, which they begin to consume after hatching. For example, the eggs of the endangered ''[[Papilio homerus]]'' are parasitized at a rate of 77%, mainly by Hymenoptera species.<ref>{{Cite journal |last1=Lehnert |first1=Matthew S. |last2=Kramer |first2=Valerie R. |last3=Rawlins |first3=John E. |last4=Verdecia |first4=Vanessa |last5=Daniels |first5=Jaret C. |date=2017-07-10 |title=Jamaica's Critically Endangered Butterfly: A Review of the Biology and Conservation Status of the Homerus Swallowtail (Papilio (Pterourus) homerus Fabricius)|journal=Insects |volume=8 |issue=3 |page=68 |doi=10.3390/insects8030068 |doi-access=free |pmid=28698508 |pmc=5620688}}</ref> Some species are even [[hyperparasitoid]], with the host itself being another parasitoid insect. Habits intermediate between those of the herbivorous and parasitoid forms are shown in some hymenopterans, which inhabit the galls or nests of other insects, stealing their food, and eventually killing and eating the occupant.<ref name=IIBD />

==Classification==
[[File:Large rose sawfly (Arge pagana stephensii).jpg|thumb|[[Symphyta]], without a waist: the sawfly ''[[Arge pagana]]'']]
[[File:AD2009Sep09 Vespula germanica 01.jpg|thumb|[[Apocrita]], with narrow waist: the wasp ''[[Vespula germanica]]'']]

The Hymenoptera are divided into two groups; the [[Symphyta]] which have no waist, and the [[Apocrita]] which have a narrow waist.<ref name=Aguiar2013/>

===Symphyta===
The suborder [[Symphyta]] includes the [[sawflies]], [[horntail]]s, and [[Orussidae|parasitic wood wasps]]. The group may be [[paraphyletic]], as it has been suggested that the family [[Orussidae]] may be the group from which the [[Apocrita]] arose. They have an unconstricted junction between the thorax and abdomen. The larvae are herbivorous, free-living, and [[eruciform]], usually with three pairs of true legs, [[proleg]]s (on every segment, unlike [[Lepidoptera]]) and [[ocelli]]. The prolegs do not have [[Crochet (insect anatomy)|crochet hooks]] at the ends unlike the larvae of the Lepidoptera.<ref name=Aguiar2013/> The legs and prolegs tend to be reduced or absent in larvae that mine or bore plant tissue, as well as in larvae of [[Pamphiliidae]].<ref>{{Cite web |last1=Baine |first1=Q. |last2=Looney |first2=C. |last3=Monckton |first3=S. K. |last4=Smith |first4=D. R. |last5=Schiff |first5=N. M. |last6=Goulet |first6=H. |last7=Redford |first7=A. J. |date=April 2022 |title=Biology and behavior |url=https://idtools.org/sawfly/index.cfm?pageID=1844 |access-date=February 15, 2024 |website=idtools.org}}</ref>

===Apocrita===
The [[wasp]]s, [[bee]]s, and [[ant]]s together make up the suborder (and clade) [[Apocrita]], characterized by a constriction between the first and second abdominal segments called a wasp-waist ([[petiole (insect)|petiole]]), also involving the fusion of the first abdominal segment to the [[Thorax (insect anatomy)|thorax]]. Also, the larvae of all Apocrita lack legs, prolegs, or ocelli. The hindgut of the larvae also remains closed during development, with feces being stored inside the body, with the exception of some bee larvae where the larval anus has reappeared through developmental reversion.{{clarify|what is developmental reversion?|date=March 2021}} In general, the anus only opens at the completion of larval growth.<ref name=Aguiar2013/>

== Threats ==
Hymenoptera as a group are highly susceptible to habitat loss, which can lead to substantial decreases in species richness and have major ecological implications due to their pivotal role as plant pollinators.<ref>{{Cite journal |last1=Spiesman |first1=Brian J. |last2=Inouye |first2=Brian D. |date=December 2013 |title=Habitat loss alters the architecture of plant–pollinator interaction networks |url=https://doi.org/10.1890/13-0977.1 |journal=Ecology |volume=94 |issue=12 |pages=2688–2696 |doi=10.1890/13-0977.1 |pmid=24597216 |bibcode=2013Ecol...94.2688S |issn=0012-9658}}</ref>

==See also==

* [[Hymenoptera Genome Database]]
* [[Insects in literature]] (ant, bee, wasp)
* [[Worker policing]]

==References==
{{Reflist}}

==External links==
{{Commons category}}
{{Wikispecies}}
{{wiktionary|Hymenoptera}}
;General
* [http://hymao.org/ Hymenoptera Anatomy Ontology project]
* [http://glossary.hymao.org/ Hymenoptera Anatomy Glossary]
* [https://web.archive.org/web/20080609224812/http://www.forum.hymis.de/ Hymenoptera Forum] German and International
* [http://www.cirrusimage.com/hymenoptera.htm Hymenoptera of North America – large format reference photographs, descriptions, taxonomy]
* [http://www.hymenopterists.org/ International Society of Hymenopterists]
* [http://www.bwars.com/ Bees, Wasps and Ants Recording Society] (UK)
* [http://www.lasius.narod.ru/ Ants Photo Gallery] (RU)
* [https://web.archive.org/web/20060924070018/http://www.sel.barc.usda.gov/selhome/sphecos/sph30ttl.htm Sphecos Forum for Aculeate Hymenoptera]
* [http://morphbank.net/Browse/ByImage/index.php?keywords=&tsnKeywords=hymenoptera&spKeywords=&viewKeywords=whole+body&localityKeywords=&listField1=imageId&orderAsc1=DESC&listField2=&orderAsc2=ASC&listField3=&orderAsc3=ASC&numPerPage=20&goTo=&resetOffset=&activeSubmit=2 Hymenoptera images] on MorphBank (a biological image database)
* [http://www.insectlifeforms.com/Orders564/ANTS_-_BEES_PLUS_WASPS_HYMENOPTERA_60502050_564.aspx Order Hymenoptera] Insect Life Forms

;Systematics
* [http://hymenoptera.ucr.edu Hymenopteran Systematics]
* [https://web.archive.org/web/20101021045815/http://hol.osu.edu/ Hymenoptera Online] 1000+ images

;Regional Lists
* [http://www.ufrrj.br/institutos/ib/ento/tomo11.pdf Insetos do Brasil]
* [http://www.landcareresearch.co.nz/research/biosystematics/invertebrates/hymenoptera/ New Zealand Hymenoptera] {{Webarchive|url=https://web.archive.org/web/20071113190650/http://www.landcareresearch.co.nz/research/biosystematics/invertebrates/hymenoptera/ |date=2007-11-13 }}
* [http://www.waspweb.org/Afrotropical_wasps/index.htm Waspweb] [[Afrotropical]] Hymenoptera Excellent images
* [https://web.archive.org/web/20131109211836/http://www.environment.gov.au/biodiversity/abrs/online-resources/fauna/afd/taxa/HYMENOPTERA checklist of Australian Hymenoptera]

{{Hymenoptera}}
{{Eusociality}}
{{Orders of Insects}}
{{Taxonbar|from=Q22651}}
{{Authority control}}

[[Category:Hymenoptera| ]]
[[Category:Cenozoic insects]]
[[Category:Extant Triassic first appearances]]
[[Category:Insect orders]]
[[Category:Mesozoic insects]]
[[Category:Taxa named by Carl Linnaeus]]
[[Category:Triassic insects]]
[[Category:Hymenopterida]]