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]
Description
Megarhyssa macrurus has a reddish-brown body of up to 2 inches (51mm) 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 (130mm) long in the female. Males are smaller and have no ovipositor.[6]
The ovipositor
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]
Distribution
M. macrurus is found across the eastern half of the United States, reaching into the extreme south of Canada near the Great Lakes.[7]
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]
↑ 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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