# Megarhyssa > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Megarhyssa > Markdown URL: https://mediated.wiki/source/Megarhyssa.md > Source: https://en.wikipedia.org/wiki/Megarhyssa > Source revision: 1315368951 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|Genus of wasps}} {{Automatic taxobox | image = Megarhyssa greenei female.jpg | image_caption = Female ''[Megarhyssa greenei](/source/Megarhyssa_greenei)'' | taxon = Megarhyssa | authority = [Ashmead](/source/William_Harris_Ashmead), 1900 | synonyms = * ''Thalessa'' Holmgren, 1859 (Preocc.) * ''Megalorhyssa'' Schulz, 1906 * ''Eurhyssa'' Derksen, 1941 }} [[File:Megarhyssa praecellens 1.jpg|thumb| Female ''[Megarhyssa praecellens](/source/Megarhyssa_praecellens)'' in China]] '''''Megarhyssa''''', also known as '''giant ichneumonid wasps''', '''giant ichneumons''', or '''stump stabbers''',[http://www.whatsthatbug.com/2014/06/25/bug-month-july-2014-female-stump-stabbers-laying-eggs/ Bug of the Month July 2014: Female Stump Stabbers laying eggs!!!], What's That Bug. Accessed 2015-06-07 is a [genus](/source/genus) of large [ichneumon wasp](/source/Ichneumonidae)s, with some species known for having the longest [ovipositor](/source/ovipositor)s of any [insect](/source/insect)s. They are [idiobiont](/source/idiobiont) ectoparasitoids{{Cite book |author1=Quicke, Donald LJ |title=The Braconid and Ichneumonid Parasitoid Wasps: Biology, Systematics, Evolution and Ecology |publisher=John Wiley & Sons, Ltd |year=2015|edition=first |page=379}} of the larvae of wood-boring [horntail](/source/horntail) wasps. The ovipositor can be mistaken for a large stinger.{{cite web |title=Giant Ichneumon Wasp - M. atrata |url=https://www.insectidentification.org/insect-description.php?identification=Giant-Ichneumon-Wasp-Megarhyssa-Atrata |website=www.insectidentification.org |publisher=InsectIdentification |access-date=19 November 2022}} This is a genus of [holometabolous](/source/Holometabolism) [insects](/source/Insect) within subfamily [Rhyssinae](/source/Rhyssinae) that includes 37 species and belongs to [Ichneumonidae](/source/Ichneumonidae), the family of [wasps](/source/Wasp) with the highest biodiversity in the world.{{Cite web |author1=Ilgoo Kang |author2=Huval, Forest |author3=Carlton, Christopher E. |title=Megarhyssa spp., The Giant Ichneumons (Hymenoptera: Ichneumonidae) |date=28 March 2023 |url=https://www.lsuagcenter.com/profiles/bneely/articles/page1587057113310 }} ==Geographical range and habitat== ''Megarhyssa'' species occur all over the world.{{Cite journal |last=Pham |first=Thi Nhi |date=2018-06-28 |title=A review of the genus Megarhyssa (Hymenoptera: Ichneumonidae: Rhyssinae) from Vietnam, with three new country records |url=https://journals.qucosa.de/jve/article/view/160 |journal=Journal of Vietnamese Environment |language=en-US |volume=9 |issue=1 |pages=22–25 |doi=10.13141/jve.vol9.no1.pp22-25 |issn=2193-6471|doi-access=free }} There are only four ''Megarhyssa'' species known to inhabit the [Nearctic](/source/Nearctic_realm) region inhabiting [decidious](/source/Deciduous) forests.{{Cite journal |last1=Pook |first1=Victoria |last2=Sharkey |first2=Michael |last3=Wahl |first3=David |date=2016-04-01 |title=Key to the species of ''Megarhyssa'' (Hymenoptera, Ichneumonidae, Rhyssinae) in America, north of Mexico |url=https://dez.pensoft.net/article/7619/ |journal=Deutsche Entomologische Zeitschrift |language=en |volume=63 |issue=1 |pages=137–148 |doi=10.3897/dez.63.7619 |doi-access=free |issn=1860-1324}} They are widespread across the United States, and Canada.{{Cite book |author1=Townes, Henry |author2=Townes, Marjorie |title=Ichneumon-flies of America North of Mexico pt. 2: Subfamilies Ephialtinae, Xoridinae, and Acaenitinae |publisher=Bulletin of the United States National Museum |year=1960 |edition= |pages=1–676}}{{Cite journal |last=Königsmann |first=E. |date=1981-05-15 |title=KROMBEIN, K. V., HURD, P. D., SMITH, D. R. & BURKS, B. D.: Catalog of Hymenoptera in America North of Mexiko. — Vol. 1, Symphyta and Apocrita (Parasitica) S. 1–1198, 1979. Smithsonian Institution Press Washington, D.C., US $ 30,00. Vol. 2, Apocrita (Aculeata), S. 1199–2209, 1979. Smithsonian Institution Press Washington, D.C., US $ 28,00 |url=http://www.crossref.org/deleted_DOI.html |journal=Deutsche Entomologische Zeitschrift |language=de |volume=28 |issue=1–3 |pages=183 |doi=10.1002/mmnd.4800280117|url-access=subscription |doi-access=free }} The species ''[M. macrurus](/source/Megarhyssa_macrurus)'', ''[M. atrata](/source/Megarhyssa_atrata)'', and ''[M. greenei](/source/Megarhyssa_greenei)'' are known to be [sympatric](/source/Sympatry) in the northeastern United States.  ''M. macrurus'' is known to inhabit further southern regions as well, reaching Mexico. ''[M. nortoni](/source/Megarhyssa_nortoni)'' has been introduced to South Africa, Australia, and New Zealand as a biological control agent.{{Cite journal |last=Taylor |first=K. L. |date=1976-12-01 |title=The introduction and establishment of insect parasitoids to controlSirex noctilio in Australia |url=https://doi.org/10.1007/BF02371642 |journal=Entomophaga |language=en |volume=21 |issue=4 |pages=429–440 |doi=10.1007/BF02371642 |bibcode=1976BioCo..21..429T |issn=1573-8248|url-access=subscription }}{{Cite journal |last=Taylor |first=K. L. |date=1978-01-01 |title=Evaluation of the insect parasitoids of Sirex noctilio (Hymenoptera: Siricidae) in Tasmania |url=https://doi.org/10.1007/BF00344686 |journal=Oecologia |language=en |volume=32 |issue=1 |pages=1–10 |doi=10.1007/BF00344686 |pmid=28308663 |bibcode=1978Oecol..32....1T |issn=1432-1939|url-access=subscription }}{{Cite journal |last1=Haugen |first1=D. A. |last2=Underdown |first2=M. G. |date=January 1990 |title=Sirex noctilio control program in response to the 1987 Green Triangle outbreak |url=http://www.tandfonline.com/doi/abs/10.1080/00049158.1990.10676058 |journal=Australian Forestry |language=en |volume=53 |issue=1 |pages=33–40 |doi=10.1080/00049158.1990.10676058 |bibcode=1990AuFor..53...33H |issn=0004-9158|url-access=subscription }}{{Cite journal |last1=Hurley |first1=Brett P. |last2=Slippers |first2=Bernard |last3=Wingfield |first3=Michael J. |date=August 2007 |title=A comparison of control results for the alien invasive woodwasp, Sirex noctilio , in the southern hemisphere |url=https://resjournals.onlinelibrary.wiley.com/doi/10.1111/j.1461-9563.2007.00340.x |journal=Agricultural and Forest Entomology |language=en |volume=9 |issue=3 |pages=159–171 |doi=10.1111/j.1461-9563.2007.00340.x |issn=1461-9555|hdl=2263/3444 |hdl-access=free |url-access=subscription }}{{Cite journal |last=Tribe GD, Cillié JJ |date=2004 |title=The spread of Sirex noctilio Fabricius (Hymenoptera: Siricidae) in South African pine plantations and the introduction and establishment of its biological control agents |journal=African Entomology |volume=12 |issue=1 |pages=9–17}} ==Description and identification== ''Megarhyssa'' male adults reach body lengths going from 2.3 to 3.8 cm (0.9 to 1.6 inches), while female adults can measure from 3.5 to 7.5 cm (1.5 to 3 inches). Both sexes can be distinguished because females have an extremely slender, and long organ to lay eggs called the [ovipositor](/source/ovipositor). This organ is much longer than the body itself, its length can range from 5 to 10 cm (2 to 4 inches). ''Megarhyssa'' adults show variation in coloration, including dark brown, bluish black, reddish brown and/or bright yellow. ===Species of the United States and Canada=== The species ''[M. atrata](/source/Megarhyssa_atrata)'' (Fabricius) shows a bright yellow head, and an almost completely black body. The wings are black as well. It can be easily distinguished from the species ''[M. macrurus](/source/Megarhyssa_macrurus)'', ''[M. greenei](/source/Megarhyssa_greenei)'', and ''[M. nortoni](/source/Megarhyssa_nortoni)'', which show yellow and brown striped color patterns that resemble one another, requiring identification by specialists. ==Ecology== The family [Ichneumonidae](/source/Ichneumonidae) is composed of [parasitoid wasp](/source/parasitoid_wasp)s. The adults do not often feed. When they do so, they feed on water droplets found on leaves that often contain [nectar](/source/nectar).{{Cite journal |last1=Heatwole |first1=Harold |last2=Davis |first2=Donald M. |date=January 1965 |title=Ecology of three sympatric species of parasitic insects of the genus ''Megarhyssa'' (Hymenoptera: Ichneumonidae) |url=https://esajournals.onlinelibrary.wiley.com/doi/10.2307/1935265 |journal=Ecology |language=en |volume=46 |issue=1–2 |pages=140–150 |doi=10.2307/1935265 |jstor=1935265 |bibcode=1965Ecol...46..140H |issn=0012-9658|url-access=subscription }} The [larvae](/source/Larva) feed on flesh from hosts the adults locate. In the Nearcctic, Palearctic, and Australian regions, some ''Megarhyssa'' species such as ''M. emarginatoria'', ''M. jezoensis'', and ''[M. nortoni](/source/Megarhyssa_nortoni)'' are [parasitoid](/source/parasitoid)s of [Siricidae](/source/woodwasps). The species ''[M. atrata](/source/Megarhyssa_atrata)'', ''[M. macrurus](/source/Megarhyssa_macrurus)'', and ''[M. greenei](/source/Megarhyssa_greenei)'' show [diurnal](/source/diurnality) activity and have undergone [allopatric speciation](/source/allopatric_speciation) and attack the [larvae](/source/Larva) of one species of woodwasp: ''[Tremex columba](/source/Tremex_columba)''. These three species are capable of coexisting with each other because their [ovipositors](/source/Ovipositor) have different lengths.{{Cite journal |last1=Pook |first1=Victoria |last2=Sharkey |first2=Michael |last3=Wahl |first3=David |date=2016-04-01 |title=Key to the species of ''Megarhyssa'' (Hymenoptera, Ichneumonidae, Rhyssinae) in America, north of Mexico |url=http://dez.pensoft.net/articles.php?id=7619 |journal=Deutsche Entomologische Zeitschrift |volume=63 |issue=1 |pages=137–148 |doi=10.3897/dez.63.7619 |doi-access=free |issn=1860-1324}} As a result, they find their [host](/source/Host_(biology)) at different depths within trees, or logs. The distance the [larva](/source/larva) is within the trunk is equal to the length of the ovipositor of each species. The ovipositor of ''[M. atrata](/source/Megarhyssa_atrata)'' is known to puncture up to 14 cm inside the wood, and such length makes this [wasp](/source/wasp) functionally the longest species in the order [Hymenoptera](/source/Hymenoptera) (if ovipositor is included).{{Cite journal |last1=Le Lannic |first1=Joseph |last2=Nénon |first2=J.-P. |date=1999-10-18 |title=Functional morphology of the ovipositor in ''Megarhyssa atrata'' (Hymenoptera, Ichneumonidae) and its penetration into wood |journal=Zoomorphology |volume=119 |issue=2 |pages=73–79 |doi=10.1007/s004350050082 |issn=0720-213X}} == Reproduction == === Reproductive cycle === The reproductive cycle of ''Megarhyssa'' begins with the female locating a [larva](/source/larva) of ''[Tremex columba](/source/Tremex_columba)'' inside the bark of a tree. She lays an egg close by or on the [larva](/source/larva), the ''Megarhyssa'' larva devours it, it [pupates](/source/Pupa) under the bark, and emerges the following year as an adult.{{Cite journal |last=Stillwell |first=M. A. |date=July 1967 |title=THE PIGEON TREMEX, ''TREMEX COLUMBA'' (HYMENOPTERA: SIRICIDAE), IN NEW BRUNSWICK |journal=The Canadian Entomologist |language=en |volume=99 |issue=7 |pages=685–689 |doi=10.4039/Ent99685-7 |url=https://www.cambridge.org/core/product/identifier/S0008347X00058788/type/journal_article |issn=0008-347X|url-access=subscription }} Males often emerge first. The species ''[M. atrata](/source/Megarhyssa_atrata)'', ''[M. macrurus](/source/Megarhyssa_macrurus)'', and ''[M. greenei](/source/Megarhyssa_greenei)'' share their territory, and habitat, showing the same behavior: males emerge, and remain close by the trees where more [wasps](/source/Wasp) from these species emerge.{{Cite journal |author1=Crankshaw, O. S. |author2=Matthews, R. W. |title=Sexual behavior among parasitic Megarhyssa wasps (Hymenoptera: Ichneumonidae) |journal=Behavioral Ecology and Sociobiology |date=1981 |volume=9 |issue=1 |pages=1–7 |doi=10.1007/BF00299846 |bibcode=1981BEcoS...9....1C }} ''Megarhyssa'' males often try to squeeze inside the holes of the bark of trees even before females emerge because preemergence [mating](/source/mating) is easier to carry out than postemergence [mating](/source/mating).{{Cite journal |author1=Heatwole, H. |author2=Davis, D. M. |author3=Wenner, A. M. |date=1964 |title=Detection of mates and hosts by parasitic insects of the genus Megarhyssa (Hymenoptera: Ichneumonidae) |journal=American Midland Naturalist |volume=71 |issue=2 |pages=374–381|doi=10.2307/2423295 |jstor=2423295 }} In females the [genital](/source/Sex_organ) opening is oriented anteriorly; in males, posteriorly. In preemergence mating, the male inserts his [abdomen](/source/abdomen) inside the hole and inside the genital opening of the female. In postemergence mating, the male must be on the abdomen of the female, and bend his [abdomen](/source/abdomen) all around it to reach her [genitalia](/source/Sex_organ) properly. Afterward, females look for a spot in the same area where the [host](/source/Host_(biology)) they need to feed their [larvae](/source/Larva) is found. Once they locate a [host](/source/Host_(biology)), females must pierce the bark of trees using the [ovipositor](/source/ovipositor) to reach the [larva](/source/larva). The exact movements of the ovipositor remain unclear, although it is known females carry out a series of movements with it: she puts the [ovipositor](/source/ovipositor) as vertically as possible relative to the wood. The intersegmentary segments must be fully unfolded and coupled to the rotation of the last abdominal [segment](/source/Segmentation_(biology)). Then, the stylus can start penetrating the wood. The [wasps](/source/Wasp) always follow a very straight line without deviating to reach the chamber where the [larva](/source/larva) lies. ===Mate choice and competition=== ''Megarhyssa'' males have been known to detect other individuals to emerge before the emergence happened. Males of the three species aggregate around the hole to find out the [sex](/source/sex) of the individual. Males do so hearing how the females bite, and chew through the wood to find their way out. If the individual is a male, many males often show little interest, and fly away. In case it is a female, males try to [mate](/source/Mating) with her as soon as possible. The [sensory organs](/source/sensory_organs) that allow the [wasps](/source/Wasp) to detect their mates, and hosts is close to the [antennae](/source/Antenna_(biology)). ===Evolution of flight=== The movement that flight makes possible for [parasitoids](/source/Parasitoid) is crucial to reproduce, so it is related directly with [fitness](/source/Fitness_(biology)).{{Cite journal |last1=Fischbein |first1=Deborah |last2=Villacide |first2=José M. |last3=De La Vega |first3=Gerardo |last4=Corley |first4=Juan C. |date=February 2018 |title=Sex, life history and morphology drive individual variation in flight performance of an insect parasitoid |url=https://resjournals.onlinelibrary.wiley.com/doi/10.1111/een.12469 |journal=Ecological Entomology |language=en |volume=43 |issue=1 |pages=60–68 |doi=10.1111/een.12469 |bibcode=2018EcoEn..43...60F |hdl=11336/71768 |issn=0307-6946|hdl-access=free }} In ''[M. nortoni](/source/Megarhyssa_nortoni)'', it is known females perform longer single flights and overall longer flights than males. It is thought this is because females are the individuals that reach new habitats, redistribute the progeny, and locate hosts. These activities require longer-range flights. Males of ''M. nortoni'' spend most of their time in aggregations around sites from which females are about to emerge.{{Cite journal |last=Nuttall |first=M. J. |date=January 1973 |title=PRE-EMERGENCE FERTILISATION OF ''MEGARHYSSA NORTONI NORTONI'' (HYMENOPTERA : ICHNEUMONIDAE) |url=http://www.tandfonline.com/doi/abs/10.1080/00779962.1973.9722978 |journal=New Zealand Entomologist |language=en |volume=5 |issue=2 |pages=112–117 |doi=10.1080/00779962.1973.9722978 |bibcode=1973NZEnt...5..112N |issn=0077-9962|url-access=subscription }}{{Cite journal |last1=Matthews |first1=R. W. |last2=Matthews |first2=J. R. |last3=Crankshaw |first3=O. |date=March 1979 |title=Aggregation in Male Parasitic Wasps of the Genus Megarhyssa: I. Sexual Discrimination, Tergal Stroking Behavior, and Description of Associated Anal Structures Behavior |url=https://www.jstor.org/stable/3494037 |journal=The Florida Entomologist |volume=62 |issue=1 |pages=3 |doi=10.2307/3494037|jstor=3494037 |url-access=subscription |doi-access=free }} Even if males are disturbed and fly away from the site, they return and regroup around the same point of the tree. They have been known to be flying around a specific tree and patrolling it over time. Such features lead to the evolution of shorter-range flights. == Species == Species within the genus:{{Cite journal |last1=Pook |first1=Victoria |last2=Sharkey |first2=Michael |last3=Wahl |first3=David |date=2016-01-04 |title=Key to the species of Megarhyssa (Hymenoptera, Ichneumonidae, Rhyssinae) in America, north of Mexico |url=https://dez.pensoft.net/articles.php?id=7619 |journal=Deutsche Entomologische Zeitschrift |language=en |volume=63 |issue=1 |pages=137–148 |doi=10.3897/dez.63.7619 |issn=1860-1324 |doi-access=free}}{{cite web |last=Yu |first=Dicky Sick Ki |url=http://www.taxapad.com |title=Home |website=Home of Ichneumonoidea |publisher=Taxapad |archive-url=https://web.archive.org/web/20181118175308/http://www.taxapad.com/ |archive-date=November 18, 2018}} *''[Megarhyssa arisana](/source/Megarhyssa_arisana)'' *''[Megarhyssa atomistica](/source/Megarhyssa_atomistica)'' *''[Megarhyssa atrata](/source/Megarhyssa_atrata)'' *''[Megarhyssa aurantia](/source/Megarhyssa_aurantia)'' *''[Megarhyssa babaulti](/source/Megarhyssa_babaulti)'' *''[Megarhyssa belulliflava](/source/Megarhyssa_belulliflava)'' *''[Megarhyssa bicolor](/source/Megarhyssa_bicolor)'' *''[Megarhyssa bonbonsana](/source/Megarhyssa_bonbonsana)'' *''[Megarhyssa cultrimacularis](/source/Megarhyssa_cultrimacularis)'' *''[Megarhyssa fulvipennis](/source/Megarhyssa_fulvipennis)'' *''[Megarhyssa gloriosa](/source/Megarhyssa_gloriosa)'' *''[Megarhyssa greenei](/source/Megarhyssa_greenei)'' *''[Megarhyssa hainanensis](/source/Megarhyssa_hainanensis)'' *''[Megarhyssa indica](/source/Megarhyssa_indica)'' *''[Megarhyssa insulana](/source/Megarhyssa_insulana)'' *''[Megarhyssa jezoensis](/source/Megarhyssa_jezoensis)'' *''[Megarhyssa laniaria](/source/Megarhyssa_laniaria)'' *''[Megarhyssa lenticula](/source/Megarhyssa_lenticula)'' *''[Megarhyssa longitubula](/source/Megarhyssa_longitubula)'' *''[Megarhyssa macrurus](/source/Megarhyssa_macrurus)'' *''[Megarhyssa middenensis](/source/Megarhyssa_middenensis)'' *''[Megarhyssa mirabilis](/source/Megarhyssa_mirabilis)'' *''[Megarhyssa nortoni](/source/Megarhyssa_nortoni)'' *''[Megarhyssa obtusa](/source/Megarhyssa_obtusa)'' *''[Megarhyssa perlata](/source/Megarhyssa_perlata)'' *''[Megarhyssa praecellens](/source/Megarhyssa_praecellens)'' *''[Megarhyssa recava](/source/Megarhyssa_recava)'' *''[Megarhyssa rixator](/source/Megarhyssa_rixator)'' *''[Megarhyssa rotundamacula](/source/Megarhyssa_rotundamacula)'' *''[Megarhyssa strimacula](/source/Megarhyssa_strimacula)'' *''[Megarhyssa superba](/source/Megarhyssa_superba)'' *''[Megarhyssa taiwana](/source/Megarhyssa_taiwana)'' *''[Megarhyssa vagatoria](/source/Megarhyssa_vagatoria)'' *''[Megarhyssa verae](/source/Megarhyssa_verae)'' *''[Megarhyssa weixiensis](/source/Megarhyssa_weixiensis)'' *''[Megarhyssa wugongensis](/source/Megarhyssa_wugongensis)'' == References == {{Reflist}} ==External links== *{{commonscat inline}} *{{Wikispecies inline}} * [http://bugguide.net/node/view/4158 Bugguide.net] * [http://cirrusimage.com/hymenoptera_ichneumon_megarhyssa_fem.htm Photo Essay: Giant Ichneumon Wasps Ovipositing] {{Webarchive|url=https://web.archive.org/web/20060315190506/http://www.cirrusimage.com/hymenoptera_ichneumon_megarhyssa_fem.htm |date=2006-03-15 }} * [http://cirrusimage.com/hymenoptera_ichneumon_megarhyssa.htm Reference Photos: Giant Ichneumon Wasps - Male ''Megarhyssa'' sp.] {{Webarchive|url=https://web.archive.org/web/20060315191746/http://www.cirrusimage.com/hymenoptera_ichneumon_megarhyssa.htm |date=2006-03-15 }} * [http://naturedocumentaries.org/3843/giant-ichneumon-megarhyssa-macrurus-ovipositing/ Video: Giant Ichneumon Wasp Ovipositing] {{Taxonbar|from=Q598790}} {{Authority control}} Category:Insects used as insect pest control agents Category:Biological pest control wasps Category:Ichneumonidae genera Category:Ichneumonidae Category:Taxa named by William Harris Ashmead --- Adapted from the Wikipedia article [Megarhyssa](https://en.wikipedia.org/wiki/Megarhyssa) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Megarhyssa?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.