Megarhyssa macrurus

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Megarhyssa macrurus
Megarhyssa macrurus female
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Ichneumonidae
Subfamily: Rhyssinae
Genus: Megarhyssa
M. macrurus
Binomial name
Megarhyssa macrurus
(Linnaeus, 1771)

Megarhyssa macrurus, also known as the long-tailed giant ichneumonid wasp[1] or long-tailed giant ichneumon wasp,[2] is a species of large ichneumon wasp.[3] It is a parasitoid, notable for its extremely long ovipositor which it uses to deposit an egg into a tunnel in dead wood bored by its host, the larva of a similarly large species of horntail.


The specific epithet of macrurus is from the Greek words makrós (μακρός) meaning "long", and oùrá (οὐρά) meaning tail.[4]


Megarhyssa macrurus has a reddish-brown body of up to 2 inches (51 mm) long.[5] It has black and yellow-orange stripes.[6] Its wings are transparent and the body elongated. The body and ovipositor together can be more than 5 inches (130 mm) long in the female. Males are smaller and have no ovipositor.[6]

The ovipositor[edit]

The ovipositor looks like a single filament, but it comprises three filaments, the middle one of which is the actual ovipositor, which is capable of drilling into wood. This central filament also appears to be a single filament, but is made of two parts, with a cutting edge at the tip. The two parts interlock and slide against each other.

Although very thin, the ovipositor is a tube and the egg being laid moves down a minute channel in its center. The outer two filaments are sheaths which protect the ovipositor; they arc out to the sides during egg-laying.[6]


M. macrurus is found across the eastern half of the United States, reaching into the extreme south of Canada near the Great Lakes.[7]


Pigeon tremex horntail (Tremex columba)

M. macrurus is harmless to humans;[6][8] they are parasitoids on the larvae of the pigeon horntail (Tremex columba, Symphyta), which bore tunnels in decaying wood.[9] Female Megarhyssa macrurus are able to detect these larvae through the bark; they paralyse them and lay their eggs on the living but paralysed larva; within a couple of weeks the Megarhyssa larvae will have consumed their host and pupate, emerging as an adult the following summer.[6]


Subspecies include:[10][11]


  1. ^ Cresswell, Stephen (2020). "Megarhyssa macrurus, Long-tailed Giant Ichneumonid Wasp". American Insects. Retrieved 2020-06-04.
  2. ^ "Long-Tailed Giant Ichneumon Wasp". MDC Field Guide. Missouri Department of Conservation. Retrieved 2020-06-04.
  3. ^ Ichneumonid wasp, Megarhyssa macrurus (Hymenoptera: Ichneumonidae). (2010-05-04). Retrieved on 2010-12-17.
  4. ^ Species Megarhyssa macrurus. BugGuide.Net. Retrieved on 2010-12-17.
  5. ^ "Giant Ichneumon Wasp: Long-tailed (Megarhyssa macrurus)". Insect Identification for the Casual Observer. 2019. Retrieved 2020-06-04.
  6. ^ a b c d e Pigeon Tremex Horntail and the Giant Ichneumon Wasp. (2010-05-12). Retrieved on 2010-12-17.
  7. ^ "Megarhyssa macrurus". Discover Life; Global Biodiversity Information Facility. Retrieved 10 July 2017.
  8. ^ "Ichneumon wasp". Archived from the original on 2010-12-10. Retrieved 2010-12-14.
  9. ^ Ichneumon wasp Archived 2010-12-10 at the Wayback Machine. Retrieved on 2010-12-17.
  10. ^ a b Pook, Victoria; Sharkey, Michael; Wahl, David (2016-01-04). "Key to the species of Megarhyssa (Hymenoptera, Ichneumonidae, Rhyssinae) in America, north of Mexico". Deutsche Entomologische Zeitschrift. 63 (1): 137–148. doi:10.3897/dez.63.7619. ISSN 1860-1324.
  11. ^ Essig Museum of Entomology Collections. Retrieved on 2010-12-17.
  12. ^ Carlson, Robert W. (1979). "Family Ichneumonidae". In Krombein, Karl V.; Hurd, Paul D. Jr.; Smith, David R.; Burks, B.D. (eds.). Catalog of Hymenoptera in America North of Mexico. Vol. 1. Smithsonian Institution Press. pp. 354–355.

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