Megarhyssa macrurus

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Megarhyssa macrurus
Ichneumon wasp (Megarhyssa macrurus lunato) (7686081848).jpg
Megarhyssa macrurus female
Scientific classification
M. macrurus
Binomial name
Megarhyssa macrurus
(Linnaeus, 1771)

Megarhyssa macrurus (common name giant ichneumon wasp),[1] is a species of large ichneumon wasp.[2]

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. Another of its common names is stump stabber referring to this behaviour.[3]


Macrurus is from the Greek words makrós (μακρός) meaning "long", and oùrá (οὐρά) meaning tail.[4]


Megarhyssa macrurus has a reddish-brown body approximately 2 inches (51 mm) long.[citation needed] It has black and yellow-orange stripes.[1] Its wings are transparent and the body elongated. The body and ovipositor together can be more than 5 inches (130 mm) long. Males are smaller (and have no ovipositor).[1]

The ovipositor[edit]

The ovipositor appears as a single filament, but it comprises three filaments. The middle filament 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. These parts have a cutting edge at the tip. They interlock and slide against each other.

Although very thin, the ovipositor is a tube and the egg moves down a minute channel in its center during egg laying. The outer two filaments are the sheaths which protect the ovipositor. They arc out to the sides during egg laying.[1]


M. macrurus is found across the eastern half of the United States, reaching into the extreme south of Canada near the Great Lakes.[5]


Pigeon tremex horntail (Tremex columba)

M. macrurus is harmless to humans;[1][6] they are parasitoids on the larvae of the pigeon horntail (Tremex columba, Symphyta), which bore tunnels in decaying wood. Female Megarhyssa macrurus are able to detect these larvae through the bark, and lay their eggs on them; within a couple of weeks, the Megarhyssa larvae will have consumed their host and pupate. They will emerge as an adult the coming summer.[1]


Subspecies include:[7]


  1. ^ a b c d e f Pigeon Tremex Horntail and the Giant Ichneumon Wasp. (2010-05-12). Retrieved on 2010-12-17.
  2. ^ Ichneumonid wasp, Megarhyssa macrurus (Hymenoptera: Ichneumonidae). (2010-05-04). Retrieved on 2010-12-17.
  3. ^ Bug of the Month July 2014: Female Stump Stabbers laying eggs!!!, What's That Bug. Accessed 2015-06-07
  4. ^ Species Megarhyssa macrurus. BugGuide.Net. Retrieved on 2010-12-17.
  5. ^ "Megarhyssa macrurus". Discover Life; Global Biodiversity Information Facility. Retrieved 10 July 2017.
  6. ^ "Archived copy". Archived from the original on 2010-12-10. Retrieved 2010-12-14.CS1 maint: Archived copy as title (link)
  7. ^ Ichneumon wasp Archived 2010-12-10 at the Wayback Machine. Retrieved on 2010-12-17.
  8. ^ a b Essig Museum of Entomology Collections. Retrieved on 2010-12-17.

External links[edit]