on hickory tree
Location:  northern mid TN
September 26, 2010 7:06 pm
We were cutting up a downed Hickory here in mid Tn and these bugs were a little territorial of their section of wood. They seemed to be male and female sticking the long tail end into holes in the wood. They were overall around 5-7 inches long.
Signature:  Tom

Giant Ichneumon Ovipositing

Dear Tom,
It is the female Giant Ichneumon, Megarhyssa atrata, that sticks her ovipositor into diseased wood because her larvae parasitize the larvae of the Pigeon Horntail that are eating the wood.  The female in your photo appears to be depositing her egg into a egress tunnel bored by either the emerging Pigeon Horntail Wood Wasp or an adult Giant Ichneumon.  We suspect it is the tunnel of the Pigeon Horntail.

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queen wasp?
Location:  Mansfield, Ohio USA
September 19, 2010 9:48 pm
Found this ”big lady” laying eggs I believe in a log in my backyard (Mansfield, Ohio) Any idea what type of wasp, I assume wasp. Pictures I know aren’t fabulous, though I do have great video. The appendage on the backend she used to deposit her eggs was 6 inches long when fully put out. Was very cool to watch.
Signature:  chris

Giant Ichnuemon Ovipositing

Dear Chris,
Theoretically, a Queen Wasp is a reproductive female that creates a nest or colony that consists of workers.  Solitary Wasps are not considered queens.  Your individual is a Giant Ichneumon, a Parasitoid species that deposits her eggs in wood that has been infested with wood boring larvae a Wood Wasp known as the Pigeon Horntail.  Your Giant Ichneumon does not form a nest or colony, so she is not a queen.  There are several species known as Giant Ichneumons, and it appears that your individual may be Megarhyssa macrurus.  You can see other examples in our archives as well as on BugGuide.  Though it might seem that the Giant Ichneumon could sting a person, her ovipositor is not multi-purpose, and she is incapable of stinging.

Giant Ichneumon Ovipositing

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what is this?
Location:  Aberdeen, United Kingdom
September 15, 2010 8:57 am
hi there, found this bug on the ground in aberdeen, uk. found outside a university. can you help identify it?
Signature:  Lewis

Sabre Wasp

Dear Louis,
This is an Ichneumon, a Parasitic Hymenopteran that is classified with bees and wasps.  In North America, similar looking Giant Ichneumons in the genus Megarhyssa prey upon the Pigeon Horntail, a species of Wood Wasp whose larvae are found feeding on dead or dying wood.  The female Ichneumon, and your specimen is a female, can be identified by her long stingerlike ovipositor which she uses to deposit her eggs in wood that is infested with the larvae of the Pigeon Horntail.  Our hypothesis is that the UK specimen you have photographed may have a similar Wood Wasp host in Europe, but without successfully identifying the species of your Ichneumon, we cannot be certain.  We found a BBC Science and Nature page that indicates that Rhyssa persuasoria, commonly called a Sabre Wasp, is the largest Ichneumon “fly” in Britain, and it is described as:  “Giant ichneumons have slender bodies, with a wasp waist, and long, flexible antennae. The apparently fearsome-looking sting at the end of the female wasp’s abdomen is actually an ovipositor (egg-laying instrument). This is protected within a sheath. This species has a black body with pale yellow/white markings on the abdominal segments. The legs are orange.“  Alas, there is no image, but the written description appears to fit your photograph.  Before leaving the BBC Science and Nature Page, we decided that the behavior description also needed to be included here:  “Ichneumons are parasites that lay their eggs in or on the larvae of other insects or spiders. The hosts of giant ichneumons are usually the larvae of horntails, or wood wasps (Orocerus gigas), and related species, as well as the larvae of longhorn beetles (Monochamus sutor). The female looks for hosts, which live within fallen timber. She may detect them through the smell of their droppings, which are then contaminated by fungi, or by sensing their vibrations within the wood. However she does it, the accuracy with which she locates them is remarkable. When she finds the right spot, she drives her slender ovipositor into the wood (which can be inches thick) by rotating the two halves backwards and forwards very rapidly. She lays one egg next to or on the host larvae. The whole process takes about 20-40 minutes. When the fly larvae hatches it feeds externally on the host. It overwinters and pupates in the spring before emerging from the wood. Giant ichneumons sometimes emerge in houses from furniture made from new timber. The adults are active from July-August.“  We found an image of a female depositing her eggs on the Insect Images website, and there is a strong resemblance to your specimen.  The Offwell Woodland & Wildlife Trust website has a nice photo and description.  Though the markings on your individual are not as pronounced, we are confident it is at least in the genus Rhyssa.

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wasp or horney
Location:  waco, texas
September 14, 2010 9:09 pm
found this in texas
Signature:  Leona Garrett
giggles76692@yahoo.com

Giant Ichnuemon

Dear Leona Garrett of Waco Texas,
We do not tolerate plagiarism or cheating from our students, and we are shocked that we may have discovered it in a letter submitted to our website.  With all the publicity currently in the press regarding the claims of a lost negative trove attributed to Ansel Adams and the possibility that the glass plates were actually taken by Uncle Earl, we are most sensitive to claims of authenticity.  Kindly explain:   How is it that this exact image that you sent to us and claim to have taken in Waco, Texas in 2010 was identified as Megarhyssa nortoni on BugGuide after being posted by Sandy Mallet with a 2007 copyright in Warwick Massachusetts?  We eagerly await your response.

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