Where Do Ichneumon Wasp Live? Truth Revealed

With their large, imposing stinger-like appendage, ichneumons are a common sight in the US. But where do ichneumon wasps live? Where do they go to, and do they make some kind of nest for themselves?

One of the largest parasitic wasps in the world, the ichneumon wasp, is quite harmless to humans. They are non-stinging wasps that only feed on flowers’ nectar. However, they do need to stay around forest areas to find a host for their eggs. 

Ichneumon wasps usually live in woodlands and damp and heavily forested areas, but they can survive in almost any type of environment. 

Let’s talk more about these wasps in this article. 

How Many Species of Ichneumon Wasp Are There?

The Ichneumon family is estimated to have around 60,000 to 100,000 known species on the planet right now. This makes them one of the largest family groups in the insect kingdom. 

Different Ichneumon species are spread all over the world and are often difficult to distinguish from one another.

While they look like bees and wasps, but you can easily identify them due to their long antennae, which comprise more than half of their entire body. 

They can vary in size between 2 inches to an impressive 5 inches. You can also spot them in various colors, with black, brown, and shades of yellow being the most prominent ones.

Where Will You Find Them?

As mentioned before, you can find a variety of Ichneumon wasps all over the globe and on every continent except Antarctica.

Even though they are spread across different parts of the world, these wasps are heavily concentrated in the United States. 

According to the Missouri Department of Conservation records, more than 5,000 species of Ichneumons can be found in North America. About 2,000 species of these wasps live in Australia, and around 2,500 are found in the UK. 

Most known species of Ichneumon wasps can easily thrive in different habitats, ranging from woodlands to wetlands to cities and the countryside.

What Kind of Environment Suits Them the Most?

Ichneumons can survive in all environments, including urban, country, wetlands, woods, etc. However, damp woodlands are the most suitable and preferred environments for them to thrive and grow. Thus, many places in the US make a perfect home for these wasps. 

Even though Ichneumon wasps are abundant in the US, humans are unlikely to spot them, let alone interact with them. You might sometimes spot one under your porch light after dark or in your garden hovering over flowers. 

Where Do They Lay Eggs?

The female wasp of most Ichneumon species needs a host insect to lay eggs. Typical hosts are caterpillars and grubs. However, different varieties of Ichneumon seek specific insects to act as the host. 

Females of the giant ichneumon wasp fly around the woods to find horntail larvae or wasps living in the trunk of a living or dead tree.

She finds these larvae by pressing her long antennae against a tree trunk. When she finds some, she bores into the trunk and lays her own eggs on these larvae.

Once the eggs are hatched, the Ichneumon larva eats the host’s body from the inside out, killing it in the process. The ichneumon larva then has to pupate and finally bore its way out of the tree trunk.

Some females also lay eggs in insects, such as chalcid wasps, boll weevils, and tomato hornworms, which otherwise cause a lot of damage to the crops. In this way, ichneumons are also beneficial insects that help in pest control.

Can Ichneumon Wasps Lay Eggs on Human Skin?

Just like the cuckoo wasp, Ichneumon wasps cannot inject their eggs into human skin. However, it is best that humans remain some distance from them because their ovipositors can still hurt. Ichneumons cannot deposit their eggs in animals like cats and dogs either. 

While their ovipositors may hurt, it cannot affect the skin of a large animal or human. Moreover,  it does not cause any health concerns either because our immune systems are strong enough to counter the small injection that the wasp would make. 

Frequently Asked Questions

Are Ichneumon wasps rare?

Ichneumon wasps are spread across the word in more than 60,000 species. Thus, they are far from being rare. They are usually found in woodlands and damp areas but can survive even in urban and dry environments.

Can Ichneumon wasps sting you?

Even though their long ovipositors seem quite threatening, Ichneumon wasps don’t sting. However, some wasps can still use their ovipositors to try and bore you if aggravated, so it is advisable to maintain your distance from them.

Do Ichneumon wasps have nests?

Ichneumon wasps do not have or construct nests. They live their lives in damp woodlands where they fly around from tree to tree, sitting on branches.

How long do Ichneumon wasps live?

On average, a giant Ichneumon wasp can live for up to 27 days, but it also depends on the host’s body, which may or may not last for long.

Wrap Up

Ichneumons are not dangerous. They live in damp woodlands, but they can be found almost anywhere.

There is no reason for a human to be afraid of them. They do not sting, and neither can they deposit their eggs in your body.

However, make sure that you keep your distance from these creatures. They are also wonderful as a natural predator for insects, so having an ichneumon around is not bad news at all.

Reader Mail

Please find below emails from readers over the years on this topic.

Letter 1 – Ichneumon, not Crane Fly

Subject:  Crane fly? Wasp?
Geographic location of the bug:  Pittsburgh, PA
Date: 10/03/2018
Time: 11:54 PM EDT
Your letter to the bugman:  Thought it was a crane fly, but most images I could find did not show crane fly with curled antennae.
How you want your letter signed:  Stacy

Dear Stacy,
This is an Ichneumon, a parasitoid wasp, not a Crane Fly.  We suspect that many reported Crane Fly stings are actually from Ichneumons.

Letter 2 – Ichneumon or Braconid???

Subject:  Stumpstabber – Megarhyssa sp.
Geographic location of the bug:  Sierra Nevada range route 88
Date: 06/23/2020
Time: 01:40 AM EDT
Your letter to the bugman:  My friend took this pic and because she knows my love of all things “bug” asked if I could find out anything about it.  Been doing some poking around and the  closest I could find was family Ichneunonidae Megarhyssa nortoni.  It’s quite striking in coloration.  Just wanted to share because I haven’t found a photo anywhere that matches
How you want your letter signed:  Terriann

Dear Terriann,
This is definitely a member of the superfamily Ichneumonoidea that includes the family Braconidae as well as the Ichneumon, and we believe this might be a Braconid, possibly in the genus Atanycolus that is represented on BugGuide.  A definitive identification might not be possible as this is a huge superfamily with many unidentified members.  According to BugGuide:  “Next to impossible to identify this genus from images alone, however it is one of the more common genera in the subfamily. Identification of images on this guide page are NOT absolute! “

Letter 3 – Crown of Thorns Wasp

non-Pelecinid?
Location:  near Casper, WY
August 2, 2010 3:22 pm
Hi Lisa Anne and Daniel,
When I photographed this creature on goldenrod 8/1/10, I thought I was looking at a Pelecinid. Now I don’t think so, I have no idea what it is. Can you identify it?
Am looking forward to your book.
Thanks much,
Dwaine

Hi Dwaine,
This is a new one for us.  You are correct that it is NOT a Pelecinid.  Our initial impulse was perhaps an Ichneumon, but the antennae and other morphological features are just plain wrong, but we were certain, based on that ovipositor, that it must be a parasitic Hymenopteran.  We quickly located the Crown of Thorns Wasp, Megischus bicolor, within the family Stephanidae on BugGuide which indicates they are “Parasitoids of beetles and/or wasps.“

Letter 4 – Ichneumon Ovipositing

ichneumon photos
on dead pin oak in SE Pennsylvania
Peter

Hi Peter,
Thanks for sending your photo of a female Megarhyssa macrurus ovipositing.

Letter 5 – Ichneumon Cocoon found on Woody Plant in Mount Washington

Subject:  What kind of cocoon did I find on my Cannabis plant?
Geographic location of the bug:  Mount Washington, Los Angeles, California
Date: 06/02/2019
Time: 5:55 PM EDT
Your letter to the bugman:  Dear Bugman.
My plants are growing taller and I have seen some tiny California Mantids and young Green Lynx Spiders prowling for prey.  It is funny how I watched the same predators on my plants last year.   There are also numerous immature hopping insects I know are not beneficial to my plants, so I have been squashing them instead of taking their picture, but today I found this very interesting cocoon thing on the leaf of a girl that grew from a seed that came from a Grand Daddy Purple X Blueberry Haze plant I grew last year.  Sorry, but I removed it before taking a photo, so I made a dramatic recreation of the way I found it on the underside of a leaf.  I hope you enjoy my still life.  Please tell me what it is.  I really want to know What’s That Bug?
How you want your letter signed:  Constant Gardener

Dear Constant Gardener,
This is a very exciting posting for us.  We instantly recognized this Ichneumon cocoon in the genus Charops from identification requests we have received from Taiwan and from South Africa.  Ichneumon Wasps are parasitoids, meaning the female wasp lays eggs on a larval host, and the larva that hatches then feeds on the internal organs of a host insect or arthropod, eventually killing the host as the larva nears maturity.  According to BugGuide:  “Known hosts include Tarachidia erastrioides (Grenee) and the green clover worm, Plathypena scabra (Fabricius), both noctuids. (Anonymous 1974)”.  You might need to add Ichneumon Wasps from the genus Charops to the list of patrolling predators in your garden.

Letter 6 – Ichneumon: Rhyssa lineolata

Subject: What is this
Location: Winnipeg mb canada
June 5, 2015 4:41 pm
What is this thing I accidentally stepped on
Signature: Kayla

Dear Kayla,
This very distinctly marked parasitic Ichneumon is Rhyssa lineolata, which you can verify on BugGuide.  We wonder how many times you are going to refer to the dictionary with this information on the feeding habits that are posted on BugGuide:  “idiobiont ectoparasitoids of the immature wood-boring endopterygote insects, in our area usually larval woodwasps (Siricidae and Xiphydriidae), but may also develop as facultative hyperparasitoids using other woodwasp parasitoids as hosts or on virtually any endopterygote (some have even been cultured in the laboratory on entirely unnatural surrogate hosts).” 

Letter 7 – Ichneumons

Dear Bugman:
I live in the San Francisco Bay area of Northern California, and for the last week or two we have had a new kind of bug flying in large numbers around our house. I’ve included some pictures of them so that you know what they look like (I apologize if the size of the e-mail causes any problems for you.) At first we thought they were just mosquito hawks, but on further examination they are much uglier. They are nocturnal and attracted to light, and we have perhaps a dozen a night or more swarming around our outside lights, and usually a few that get inside the house. They are about an inch to an inch and a half in length, and are one of the more disturbing bugs I’ve seen. They don’t seem to match up with any of the pictures I found of termites or flying ants, but I really want to know if they are since that would be a big problem for the house! At about the same time these bugs appeared, there also have cropped up a couple of spots on the lawn where the dirt looks almost bubbly – I have no idea if that’s related, but I thought it may be some kind of nest. Please let me know what kind of bug this is so I can stop worrying or get rid of them, whichever is appropriate.
Thank you very much.
Helga

Dear Helga,
Seldom do we get such a concise description accompanied by such wonderful documentation. There is no speculation regarding my identification. You have a species of Ichneumon wasp, Family Ichneumonidae. These are small solitary wasps which have smaller and slenderer bodies and legs than social and semi-social types. The abdomen is compressed from side to side. Some species are as small as gnats, and the larger ones are up to an inch in length. The specimen you photographed belongs to the genus Ophion. All Ichneumons are parasitic on other insects, and many feed on caterpillars. According to Hogue, "The eggs are inserted into the body of the host by means of the females short sharp ovipositor (which incidentally can penetrate human skin). The larvae feed on the internal tissues and, when mature, pupate within the host." They are important biological controls for many agricultural pests. Your possible nest is obviously something else. The adults are often attracted to lights at night.

Thank you very much. Now I can stop worrying. 🙂
Helga

Letter 8 – Ichneumons

I was outside this morning at about 8:00 am. I live in West Virginia. I happened to look at the corner o my house near where my gas meter is and saw a real strange bug sitting on the wall. It was very dark blue or black had a body that was about 1.5 to 2 inshes long ( approx) . Had wings that were about an 1.5 or so. Had a curved body. It also had this stinger or something ( not sure what to call it. That was about 1/32 inch in diameter and about 5 or 6 inches long. I watched it for a minutes and it flew off. It was so large that i could see it 50 feet away in the air. Do you have any idea on what it was or where i can find information on flying insects? any help will be great.
Big Bad Bob

Dear Bob,
Let me commend you on your excellent verbal description. I believe it is a female Ichneumon Wasp, probably Megarhyssa atrata. She uses that long ovipositor to deposit her eggs deep into wood where the young search out and devour wood eating grubs. Very specialized development that would interest all Darwinians.

Letter 9 – Ichneumons

I work at a garden store in South-eastern Wisconsin, and recently I caught some type of what I think is a wasp, ITs all black exept for yellow legs, its abdoman is very narrow at first and strechtes into somthing similar to a mud wasp exept it is much bigger. The strangest thing about this insect is it has thrre "tails" or entenas coming directly out of the stinger withc are aproxemiely 5" long. I am stumped, what kind of wasp is this?

Probably a female Ichneumon Wasp, Megarhyssa atrata.

Letter 10 – “Off With Their Heads” Ichneumons

Subject: What the … Is this?
Location: Maryland USA
May 24, 2016 7:54 pm
I’ve seen wasps and crane flies. This seems to be closer to a wasp. When I tried to be sparing and set it free it attempted to sting me numerous times while not being able to break the skin it seems. It got back inside and brought family ( see photo 2) there does seem to be a stinger on them. I did in fact kill them both. Only get one shot in my house unless your a spider, then you get none. Anyways, do you have any idea of what this is? If you have some photo reference if greatly appreciate it. Thanks!
Signature: Chris Joy

Dear Chris,
We are very curious about your mini-guillotine, because we cannot fathom how you have managed to kill these two Ichneumon Wasps by removing their heads but otherwise leaving their bodies intact.  Most wasps in the family Ichneumonidae, probably the largest family on earth with the most individual species, are perfectly harmless, but members of the subfamily Ophioninae is capable of stinging.  According to BugGuide:  “Females have a very compressed abdomen and a short, very sharp ovipositor. The ovipositor can penetrate the human skin; most other ichneumons can’t ‘sting’.”  BugGuide also notes:  “Most species are crepuscular or nocturnal, some diurnal. They are known to come to lights.”  These Ichnuemons are solitary, and they did not conspire together to enter your home.  We suspect they were attracted to lights.  When folks write to us about stinging Crane Flies, we suspect they have confused them with members of this subfamily.

Dear Daniel,
I appreciate your response. That was what I suspected them to be. As far as mini guillotine, well the answer there is just an old fashion credit card and hitting them before they could fly away that simple. But thank you for answering my question I know you all are busy and I’m glad you had the time to respond.
VR
Chris

Letter 11 – Ichneumons from Italy

Subject:  Flies
Geographic location of the bug:  Italy (Rome)
Date: 03/05/2019
Time: 05:42 AM EDT
Your letter to the bugman:  Hi bugman! Upon return from a week out, we found a lot of these ‘flies’ dead around the house, mostly in the bathroom. We had left a basket with walnuts, almonds and hazelnuts in the living room, so that might have attracted them? Not sure.
Anyway, are you able to identify them?
Thanks as always!
How you want your letter signed:  Saverio

Dear Saverio,
These are not Flies.  They are Hymenopterans, the insect order that includes Bees and Wasps.  They appear to be parasitoid Ichneumons, a group of solitary wasps that parasitize their prey.  The Ichneumon larva develops inside the body of the prey, feeding on its internal organs until the host dies, at which time the Ichneumon larva pupates, eventually emerging as winged adults.  We suspect your sighting is related to an emergence while you were away.  This occurrence might be related to the basket of nuts, but we are not convinced.  How large were these Ichneumons?  Exact species identification might not be possible.  According to the North American site BugGuide:  “arguably, the largest animal family, with the estimated 60,000 species worldwide (up to 100,000, according to some estimates” and many species are undescribed.

Letter 12 – Ichneumons from UK

Subject: What is this bug?
Location: Hatfield Forest UK
February 19, 2017 9:56 am
Good evening
We saw these bugs under tree bark of felled tree in Hatfield forest.
Do you know what it is please?
Thank you
Signature: Claire

Dear Claire,
Though your image lacks critical detail, we are relatively confident these are parasitoid Ichneumon Wasps.  Some species feed on wood boring insects, which may explain their presence under the bark of a felled tree.  This images from Nature Spot of Achaius oratorius look similar.  Ichneumon stramentor, also on Nature Spot, looks like an even better match.  According to Nature Spot:  ” The larva parasitise the Large Yellow Underwing and Setaceous Hebrew Character moth caterpillars (possibly others), the adult wasp lays its eggs inside the caterpillar, the developing larva then eats it from the inside.”  You can also find some interesting information on Paul’s Back Garden Safari.

Letter 13 – Ichneumon species

A huge gorgeous bug
Here is a picture of a two-inch wingspan bug I ushered out of my house
in Mid-Maryland last night. Any clues?

This is a female Ichneumon. We are not sure of the species.

Letter 14 – Ichneumon Stalks Caterpillar

Subject: Red mystery wasp
Location: near Ottawa, Ontario
July 18, 2016 3:43 pm
What is this beautiful little insect? I’m guessing some sort of wasp, maybe a parasitic wasp? I photographed it last week along Cedar Grove Nature Trail near Ottawa, where I see many fascinating tiny insects I can’t identify!
Signature: Suzanne

Dear Suzanne,
This is an amazing image.  We suspect that the Ichneumon Wasp, which you speculated correctly is a parasitoid, is stalking the Caterpillar.  Caterpillars are a common host to many species of Ichneumons.  Ichneumons are often very host specific, frequently limiting their prey to a single genus, or even a single species.  We are probably not even going to attempt to identify this Ichneumon beyond the family level as according to BugGuide, there are:  “About 5,000 described species in North America, possibly 3,000 more undescribed”  The caterpillar may be an Inchworm in the family Geometridae.

Letter 15 – Ichneumon from UK

Subject: Insect Identification
Location: South East UK
October 20, 2014 10:54 am
Afternoon,
Found the attached against my curtains this evening
I literally have no idea what it is or what it could be and have been searching images for the last hour trying to find out
Wondering if you could let me know what it is and if it is native to the uk? i have never seen anything like this and i have lived here all my life (some 27 years)
Signature: Thank you in advance

This is some species of Ichneumon, a member of a family of parasitic wasps.  Ichneumons prey upon many agricultural pests and most Ichneumons are very host specific, preying upon a single species or genus, though some prey upon entire families of insects and arthropods.  Ichnuemons are a highly diverse family with many members, and we cannot say for certain if you have a native species.  Ichneumons are sometimes introduced to prey upon other introduced pests.

Letter 16 – Ichneumon Wasp

Hi. I wonder if you could let me know what these are, I live in the UK, and have looked up several books and Web sites but can’t seem to find them.
Thanks
Eric

Hi Eric,
It is a species of Ichneumon Wasp. They usually parasitize caterpillars among other insects

Letter 17 – Ichneumon Wasp

Lovely…but what is it?
Location: Maryland
April 3, 2012 1:02 pm
This one has me stumped. I’ve checked my Audubon guide and typed the description into search engines…so far, nothing that is an exact match. Location: Maryland.
Signature: Barbara Thurlow

Dear Barbara,
This truly is a gorgeous photo of a beautiful parasitic Hymenopteran.  We were pretty certain it is classified as an Ichneumon Wasp, and upon browsing BugGuide thoroughly, we believe we have found a match in an unidentified species in the genus Melanichneumon.  This unidentified species of a male Ichneumon posted to BugGuide also looks similar, but it is only identified to the subfamily level.

Letter 18 – Ichneumon, we believe

Subject: Small Parasitic Wasp
Location: Rose Hill, CA
October 3, 2012 9:24 pm
Dear Bugman,
I just found this little miss as I was cleaning up my kitchen. I only know she is a wasp but I have no idea what kind. She is approximately 1/2” long excluding her antennae.
Signature: joAnn

Hi joAnn,
Your photos are of excellent quality, however, we do not believe we have the necessary skills to provide you with a species identification.  We agree that this is a parasitic wasp, most likely an Ichneumon.  According to BugGuide, the family contains:  “About 5,000 described species in North America, possibly 3,000 more undescribed(2); arguably, the largest animal family, with the estimated 60,000 species worldwide (up to 100,000, according to some estimates(3).)”

Good morning Daniel,
Thank you for that identification!
In looking at the images on BugGuide as well as others on the internet I agree on Ichneumon. Ironically as a kid that was one of my favorite insects to name out of one of my insect books yet I never realized that they came in such a diminutive size. I have a whole new found fascination for last nights house guest.
Best,
joAnn

Letter 19 – Ichneumon we believe

Subject: Wasp mimic?
Location: Columbus, OH
March 27, 2017 7:41 am
Hello! This insect landed on me and I cannot for the life of me figure out what it is (my best guess is some sort of sawfly). This picture was taken on March 25th in central Ohio in an urban enviornment–I was actually about to get in my car when it was spotted. The weather was sunny and in the 70’s. I am especially perplexed by the super long antenna and the fact that the colored bands on the abdomen do not wrap all the way around. Thanks!
Signature: Intrigued

Dear Intrigued,
We are posting prior to doing any research as we are rushed right now, but we believe this is an Ichneumon, a member of a very large family of Parasitic Wasps, that are often recognized by long antennae.  Here is a similar looking Ichneumon in the genus Banchus from BugGuide.

Letter 20 – Ichneumon, we believe

Subject:  What is this flying bug
Geographic location of the bug:  Sacramento California
Date: 11/05/2018
Time: 10:50 PM EDT
Your letter to the bugman:  This was buzzing at me fairly large dont know what it is.
How you want your letter signed:  Weirdbug

Dear Weirdbug,
This sure looks like an Ichneumon to us, or some other parasitoid wasp, but we have not had any luck with a definitive identity.  We wish there was more detail in your image.  Ichneumons are parasitoid Wasps that are considered important biological control agents for caterpillars and other insects.  According to BugGuide:  “a great variety of hosts (mostly immature stages) is used, though most species attack only a few host types; some infest spiders and other non-insect arthropods.”   The wing veination on your individual appears very similar to the drawing on Le Monde des Insectes.

Letter 21 – Irish Ichneumon

Hi,
I found this bug on my kitchen window, had to take a photo as i have never seen one like it before. I live in Belfast N.Ireland and curious to know if this is a local insect or unknown to Ireland.
Many thanks
Una.

Hi Una,
This is some species of Ichneumon. If it was from the U.S. I would say it was the genus Megarhyssa. It might be. At any rate, it is one of the Ichneumons.

Letter 22 – Male Ichneumon

can u tell me what this is
i found this guy in a casino out side of chicago
stephon young
chicago il

Hi Stephon,
We believe this is a male Ichneumon in the genus Megarhyssa. We usually get photos of the females with their extremely long ovipositors. We will check with Eric Eaton to get a second opinion.

Letter 23 – Male Ichneumon

Subject:  need help identifying this wasp
Geographic location of the bug:  Occoquan NWR, Occoquan Virginia
Date: 09/22/2018
Time: 08:33 PM EDT
Your letter to the bugman:  Once more I must ask for you excellent help. I cannot seem to find what species this attractive wasp is in any of my usual resources (including your wonderful site, of course!) Thanks very much in advance.
How you want your letter signed:  Seth

Dear Seth,
This is a parasitoid wasp in the family Ichneumonidae, and according to BugGuide:  “~5,000 described spp. in almost 500 genera in the Nearctic Region, possibly 3,000 more undescribed; arguably, the largest animal family, with the estimated 60,000 species worldwide (up to 100,000, according to some estimates.  Those numbers mean that species identifications can be very challenging. Your individual looks very similar to Lymeon orbus based on this BugGuide image, but your individual lacks an ovipositor, making it a male, and your individual has a black band on the hind leg lacking in the images we have located of Lymeon orbus.  So, we are certain that this is an Ichneumon Wasp, we are nearly certain it is a male, and beyond that, we need to defer to real experts.  If you find any closer visual matches, please let us know.

Letter 24 – Male Ichneumon, we believe

Subject: Sawflies
Location: Southwest MI, USA
October 18, 2013 4:08 pm
Happened to see this fellow on a marigold. Had never seen one before but after looking online, my best guess it is some sort of sawfly. Can you identify it for me?
Signature: d.k. dodge

Hi d.k. dodge,
We believe this is a male Ichneumon, and that family, according to BugGuide, contains:  “About 5,000 described species in North America, possibly 3,000 more undescribed(2); arguably, the largest animal family, with the estimated 60,000 species worldwide (up to 100,000, according to some estimates.”  We have contacted Eric Eaton for confirmation.

Eric Eaton confirms
Yes, an ichneumon.  Not sure what gender, though.  Not all female ichneumons have a visible ovipositor.
Eric

Thank you.  The body type would be consistent with many ichneumons, so I’m not surprised.  I anxiously await more confirmation.

Letter 25 – Newly emerged Ichneumon

Subject:  Ichneumon
Geographic location of the bug:  Campbell, Ohio
Date: 08/02/2021
Time: 8:46 AM EDT
Gentle Readers,
Daniel has been taking many images of interesting creatures using his magicphone (his first cellular telephone ever which he has had for the past year) because the iPhone pro has a marvelous camera.  Last week one morning while enjoying coffee in the garden, Daniel spotted this parasitic wasp, presumably an Ichneumon, preening on the tip of a blade of grass, so he picked the blade of grass to get a better look.  He realized by the preening he observed that this was probably a newly emerged wasp that had not yet flown.  It seemed it was checking out its new sensory organs, the antennae, and Daniel observed for about a half an hour before it finally flew off.  Ichneumon Wasps and their relatives the Braconids and the Chalcids are all interesting parasitic wasps that often prey on a single species.

Letter 26 – Parasitic Hymenopteran (Ichneumon or Braconid?) from Germany

Wasp? Horntail? in Thuringen Germany
Location: Central Germany
November 15, 2011 6:51 pm
I took this photo with a 100mm Macro in Heilbad-Heilegnstadt Thuringen, Germany.
It measured less than 1/2 inch, as you can see from the veins of the leaf.
I have tried to identify it to no avail.
Please help
Signature: Laurel R.

Hi Laurel,
This is a Parasitic Hymenopteran, most likely an Ichneumon, but possibly a Braconid.  She is a female and the stingerlike ovipositor is used to lay eggs inside the host, generally an insect.  Ichneumons and Braconids are important biological control agents that are usually very host specific.  We rarely attempt to identify most Ichneumons and Braconids to the species level as it is a task best left to specialists.

Thank you Daniel! I searched and searched to id that little wasp, even with your further information I could not find
a photo of it.
I live in Nyack, New York about 20 miles north of New York City. I have been writing about the insects in my garden
daily since July. The variety of species is amazing!
The photos are from my recent trip to visit my son in Thuringen.
Sincerely,
Laurel Robertson

Letter 27 – Unknown Ichneumon

Subject: What Kind of Bug is this?
Location: Suburbs of Chicago
May 27, 2016 6:01 pm
I am a student photographer and as an assignment I am to photograph nature and then explain my pictures. I took about 100 pictures (manual and automatic, color and black and white). After looking online no one in my family can identify this bug. It seems to not be using its 5th and 6th legs and it isn’t flying, maybe a wing is broken.
Signature: Autumn

Dear Autumn,
We do not yet have a species identification, but we have determined that your parasitic Wasp must be in the superfamily Ichneumonoidea, which according to BugGuide has only two families, the Braconids and the Ichneumons.  Our money was originally on this being a female Braconid, but our browsing through both families on BugGuide did not produce species that even looks similar.  We are posting your request as Unidentified and we hope it does not remain so tagged for long.

Eric Eaton Responds
Hi, Daniel:
Definitely an ichneumon, and pretty, but I have no idea which one.  Sorry!
Eric

Letter 28 – Parasitic Wasp: Ichneumon Species

Horntail?
Hi Bugman,
Very cool site; I must check in at least once a week. I am an avid macrophotographer and came across this insect in Delaware on Nov. 14th. I am quessing it may be a Horntail. The last tergite of the abdomen has a spike that resembles an ovipositor. It was found on a pokeweed in a white pine forest. Its body lenght was about 2.5 cm minus the antenna and spike. I checked my field guides and did a few internet searchs to no avail. Any ID assistance would be appreciated. Thank you,
William Brozy

Hi William,
What a gorgeous photo. We flipped it to maximize its size on our site. This is a Parasitic Wasp in the superfamily Ichneumonidae. We are not sure if it is a true Ichneumon, or a Brachonid. We will see if Eric Eaton can provide an answer. Eric wrote in that in his opinion, this is an Ichneumon.

Letter 29 – Possibly Ichneumon from Alaska

Subject:  Insect That has Taken South Central Alaska by Storm
Geographic location of the bug:  Anchorage Alaska
Date: 09/19/2021
Time: 12:20 AM EDT
Your letter to the bugman:  I am looking to ID this insect. They seem to be appearing everywhere over the last two weeks in Anchorage AK. This particular specimen may have a missing leg, but most do not. It seems similar to wood wasps I have seen before, but is smaller at ~1” long. Thanks for the help!
How you want your letter signed:  Scott P

Dear Scott,
We believe this is an Ichneumon, a parasitoid wasp, or possibly a Braconid, also a parasitoid wasp, and both are in the superfamily Ichneumonoidea, which is according to BugGuide:  “A very biodiverse and important group. Many are valuable biocontrol agents that control populations of agricultural and forest pest insects. Wasplike in appearance, but (with rare exceptions) do not sting. “

Letter 30 – Probably Ichneumon from Canada

Subject:  Red-yellow-black winged ant?
Geographic location of the bug:  Ottawa, Ontario
Date: 10/13/2017
Time: 01:01 PM EDT
Hi, Bugman! It’s starting to get cold out and I’ve been seeing occasional coniferous seed bugs around inside, but today I found this striking creature. What beautiful colours she has! Despite the distinct pattern and yellow mark on her back, I’m not sure what she is. Not like the paper wasps I’ve seen. Some sort of wasp or flying ant (because of the way the wings sit)? She wasn’t hostile but flew back to the windowsill when I attempted to move with a paper.
How you want your letter signed:  With a casual interest in entomology, Dannie

Dear Dannie,
We believe this is a parasitoid Ichneumon, a relative of bees and wasps.  According to BugGuide:  “They vary greatly in size and color; many are uniformly colored, from yellowish to black and others are brightly patterned with black and brown or black and yellow; many have middle segments of antennae yellowish or whitish.  The majority resemble slender wasps but differ from the stinging wasps (Scolioidea, Vespoidea and Sphecoidea) in having longer antennae with more segments (usually at least 16). Many have long ovipositors, often longer than the body.  Ichneumonids are notoriously hard to identify: aside from the sheer number of species, there are numerous cases of distant relatives that appear almost identical. Any identification based solely on comparing images should be treated as suspect unless an expert has said there are no lookalikes for the species or group in question.”

Letter 31 – Ichneumon from Australia

What the hell is this?
Location: Adelaide, Australia
November 19, 2010 12:01 am
I’m thinking a wasp of some kind, but I cant find anything about it on the internet. Picture is kinda poor, but best I could get. It is rather big for an insect. Long, slender, black body. Big wings. Two long things that look like stingers. Very long antennae. Lets off a very strong and strange smell when threatened. Very loud when flying around. Body is extremely hard, extremely difficult to kill. Seriously, I squashed this thing last night and come back to it today and it is still moving. I find one or two of these things in my house about every six months or so.
Signature: Scott

Dear Scott,
Your photo is quite blurry, so we cannot be certain, but we believe this is some species of Ichneumon, a group of insects in the order that includes wasps and bees.  Ichneumons are parasitoids and the female lays her eggs on or near the prey.  Larval Ichneumons are internal parasites that eventually kill the prey.  Many Ichneumons prey upon caterpillars, but depending upon the species, they have a wide variety of insect and spider hosts.  Ichneumons do not pose a danger to humans.  We could not find a close match on the Insects of Brisbane website Ichneumon page, but the antennae on your specimen are a primary factor in our tentative identification.

Karl provides another identification
Hi Daniel and Scott:
It looks like a Cream-spotted Ichneumon (Echthromorpha intricatoria). The species is found all over Australia and has been introduced to New Zealand, where it is known as the Whitespotted Ichneumon. The larvae are parasitic on the pupae of a variety of butterflies and moths. Regards.  Karl

Letter 32 – Striped Ichneumon: Unnecessary Carnage in Wisconsin

Subject: As coined by a commenter – a Nope Striped Nopey Nope Nope
Location: South Eastern Wisconsin
August 7, 2015 7:03 am
Good Morning!
First off, thank you for providing such a valuable resource for us “what in the heck is this thing”ers; it has helped solve more than a few similar situations and I continue to direct people here when they have bug identification questions (and to donate).
This morning a friend of mine posted the attached pictures (apologies for the blurriness) asking for help. At first glance it was assumed to be a black and yellow mud dauber, but the abdomen seems to be much too large (as well as striped). I had attempted (in vain) to identify what the forked end on the abdomen was as well, but looking at it now I think it may just be other parts (legs?) that are folded under the body. Also, the fat thorax (much larger than I’m accustomed to around here) throws me for a loop. The segmentation just doesn’t seem right for a wasp.
Sadly, this little guy (gal?) said hi to individuals who were less than hospitable and was swatted down in their prime.
Thanks for your help in advance!
Signature: Matthew

Dear Matthew,
Based on the long antennae, we decided to begin our searching among the parasitic wasps known as Ichneumons, and we quickly found a similar looking individual identified as Setanta compta on the Nature Search site, but the striping on that individual goes to the tip of the abdomen while your individual has a black tipped abdomen.  The striping on the legs is also different, but we still turned to BugGuide to see if there was more variation in the species.  We then determined you have a different species, and we located a very good match on BugGuide, but alas, it is only identified to the tribe Ichneumonini.  Your individual also looks similar to Diphyus palliatorius pictured on the French language page Aramel.Free.  According to BugGuide, in the family Ichneumonidae there are:  “About 5,000 described species in North America, possibly 3,000 more undescribed; arguably, the largest animal family,”  and we don’t believe we will be able to provide you with an exact species identity, but we do believe the closest we can come is the unidentified individual on Bugguide.

You are incredible – thank you so much for your work in this! I can’t imagine how much time you, and your team, invest into these requests, but know that it is sincerely appreciated.
best regards,
-Matthew

You are most welcome Matthew.  Were it not for identification requests with excellent images, we would not have much of a site.

Letter 33 – Unidentified Ichneumon from Canada in the Pacific Northwest

Subject: Wasp ?
Location: Victoria BC Canada
June 26, 2014 10:13 pm
I have a group of these flying around one section of my property. They look like wasps, but are much thinner and longer. They hover low to the ground, seeming to fly in circles, and dont seem to be going to a ‘ nest ‘ that I can see. They also do not seem to be aggressive like the other pesky wasps…yet. They have been hovering in the same area now for just about a week
Are these a threat to my Pets, and what are the advantages / disadvantages to them and how do I get rid of them.
Thanks
Signature: Randie Ruckle

Dear Randie,
In 2008, we posted some images that were identified as Ichneumons, members of a family of wasps that parasitize other insects and sometimes other arthropods, but as it is a very large family, we never drilled down to the species level.  Recently there has been a flurry of comments from the Pacific Northwest to that posting including reports of stings or bites, and since you have provided us with new images, we have decided to see if we are able to properly identify this Ichneumon and provide any relevant information.  This may take some time, but we will work on it.  Your Ichneumons seem to resemble members of the tribe Ichneumonini based on BugGuide images, but they might be in a different tribe.  BugGuide states:  “About 5,000 described species in North America, possibly 3,000 more undescribed; arguably, the largest animal family, with the estimated 60,000 species worldwide (up to 100,000, according to some estimates,” and they do have an extensive archive of Ichneumons.   Pouring through it will take some time.  If the information we have provided leads you to an identification before we get back to you, please give us an update.

Update:  We did locate a matching image on Island Nature devoted to Vancouver Island, but it is not identified.

Thanks so much for the info.
I think my concern is there are alot of them in that section. I would say about 50 at least, all hovering ( flying )  just about ground level. From what I have read in Wiki, they ae supposed to be solitary.  There does not seem to be a ” nest ” that I can see them going to. The area is about 10 x 20 feet, give or take, that they are congregating in.  I dont really want a group of stinging insects around with my 2 19 year old dogs and my indoor/outdoor cat.
Thanks again. Any info is great !
R

Letter 34 – Unknown Ichneumon

Beautiful Ichneumon
Thu, Jul 2, 2009 at 6:48 PM
Hello! I found this incredible creature flying around in the grass on a warm June night in Western Massachusetts. I think it is an ichneumon, but I just can’t seem to find out much more. Can you tell me its species? Thanks so much!
Jamie
Sheffield, MA

hi Jamie,
We agree that it is an Ichenumon, and we agree that it is beautiful, but we are uncertain of the exact species. We will contact Eric Eaton to see if he can provide any additional information. We will also post your letter in the hope that one of our readers knows more than we do. We would recommend that you either keep checking the posting to see if there has been a comment, or better yet, supply an additional comment to the posting with any additional information that may be helpful. Then if a reader provides a comment with an identification, you will automatically be notified.

Update
Daniel:
Yes, it is an ichneumon, but no telling what subfamily, let alone genus or species, without the specimen in hand.
Take care, enjoy the holiday weekend….
Eric

Letter 35 – Unknown Ichneumon

Subject: Unknown wasp or ichneumon
Location: Island Park, Idaho
July 27, 2012 3:26 pm
Could you identify this flying bug for me. It was shot in Island Park, Idaho in July 2012.
Signature: Brent

Hi Brent,
We agree that this is some species of Ichneumon, but after browsing through the BugGuide possibilities twice with no luck at a species or genus identity, we are unable to provide you with that information.  We are posting it as an unidentified Ichenumon and perhaps we will be able to determine the species in the future.

Letter 36 – Unknown Ichneumon

Subject: Pacific Northwest Ichneumon
Location: Renton, WA
May 28, 2015 4:28 pm
I’ve been seeing about 50 of these guys parade my front and back yard over the grass areas. They do not seem to be harmful, and only hover over the grass areas. I did research and came across your website to find out it’s an “ichneumon wasp” according to Eric Eaton on another post. Would you happen to know where they nest or why they’re parading my lawn areas for? At first they looked like yellow jackets, but their bodies are much too skinny and orange to be. The pics I’ll include are from a few days ago. Any info would be great. Thanks.
Signature: Stephanie

Hi Stephanie,
We noticed your comment on the other Ichneumon posting, and we still are not able to provide a species identification for this Ichneumon.  Ichneumon Wasps do not build a nest.  They are parasitoids of a variety of insects and arthropods, and they are generally very host specific.  The female lays an egg on a host, or sometimes she uses her ovipositor to deposit eggs within the host.  The larvae then feed on the still living host.  Again, Ichneumons are not social wasps, but they are very important natural, biological controls for other insect populations, hence they are beneficial.  Most Ichneumons are perfectly harmless to humans, though members of the genus Ophion are known to sting, but they are still not considered harmful to humans.

Letter 37 – Unknown Ichneumon from Australia

Subject: What kind of wasp is this?
Location: Adelaide, South Australia
December 16, 2013 8:28 pm
Hello,
I found this in our backyard and was wondering exactly what it is and is it dangerous. We live in Adelaide, South Australia. Thanks.
Signature: Jacob

Hi Jacob,
This is some species of Ichneumon, a large and diverse group of parasitoid wasps that are not considered dangerous to humans.  The female uses her ovipositor, which is visible in your photo, to deposit her eggs, often directly into the body of the host insect or arthropod.  Most Ichneumons are very host specific, and the prey include many different orders, including butterflies and moths, true bugs and other wasps.  We hope to eventually determine a species identification for this unusual Ichneumon.

Letter 38 – Unknown Ichneumon from Costa Rica

Subject:  What’s this yellow wasp?
Geographic location of the bug:  Costa Rica, Nicoya Peninsuala
Date: 12/09/2019
Time: 05:49 PM EDT
Your letter to the bugman:  Hi there! I’m living in Costa Rica and accustomed to all manner of crazy bugs, including having many, many paper wasps making my home their home. I’ve come across a very pretty wasp today, however, which I’ve never seen before. Any time there’s only one of something and it’s abnormally pretty, I start to wonder. I was hoping you could help me identify my new kitchen guest and let me know if I should be nervous about the surprisingly long stinger or not.
(sorry about the dust…it’s a daily accumulation, it’s crazy down here!)
Thanks in advance!
How you want your letter signed:  Monique

Dear Monique,
We believe this is a parasitoid Ichneumon, a harmless solitary Wasp, but we have not had any luck finding any similar looking individuals online.  According to BugGuide:  “arguably, the largest animal family, with the estimated 60,000 species worldwide (up to 100,000, according to some estimates”  and “Ichneumonids are notoriously hard to identify: aside from the sheer number of species, there are numerous cases of distant relatives that appear almost identical. Any identification based solely on comparing images should be treated as suspect unless an expert has said there are no lookalikes for the species or group in question.”  Ichneumons are important biological control agents and many species prey on caterpillars.  The female uses her long ovipositor (not a real stinger) to lay eggs inside the body of the living host and the larva that hatches will feed on the internal organs of the host, eventually killing it.

Thank you Daniel!
I used your identification in Google Images and, instead of getting moths like searching my image did, I found many similar images, so I completely trust your ID. She really was pretty and I hope that she finds a nice caterpillar nearby to help her hatch a lovely family.
Thanks for such a quick reply!
Monique

Letter 39 – Unknown Ichneumon Wasp

Another question
Dear Bugman,
First of all, you guys are awesome. I’ve sent photos of several different insects and arachnids your way and you always help out the best you can when it comes to identification. I commend you for always being courteous and prompt (when you can be). Now that I’ve done my quota of kissing butt, here are some more photos of critters I could use some help with. I only publish amateur photos on my website, so most of the time the species of creature is in question. Don’t get me wrong, I can tell an arachnid from an insect and an amphibian from a reptile, but whenever possible I prefer to positively identify a critter’s species. If you can even just point me in the right direction "order"-wise, I can probably find it. If you can give me the actual species…even better. Thanks in advance,
Stefan Bowers

Hi Stefan,
Most importantly, where are you located? This is some species of Ichenumon. We believe it may be a male Giant Ichneumon in the genus Megarhyssa. Your moth is one of the Sphinx Moths, but we need to research what species. We are posting yout two insects separately as putting different orders in one posting complicates our already disorganized archives.

Update: (05/11/2008)
Hi, Daniel:
A couple quick corrections to recent postings, if I may: The “Unknown ichneumon wasp” is NOT a male of Megarhyssa. Most ichneumon wasps are essentially impossible to identify beyond family from an image alone. Even specimens can be problematic! The one imaged here resembles the genus Ophion, but in no way can I be positive of that. … Cheers,
Eric

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Giant Ichneumon

Dragonfly / Hornet / ?
Good Day,
I haven’t seen this type of flying insect in our area (Southern Ontario) until it tried to dive bomb my head while I was sitting on our deck. It eventually landed on our shed and I was able to take a couple of shots. It’s body is about 2" long. Including the tail it is about 5-6" long! Thanks for any info you can provide. Great site!
Chris Glos
Windsor, Ontario

Hi Chris,
This is a Giant Ichneumon, Megarhyssa macrurus, and though it is related to wasps, it does not sting. That is an ovipositor for laying eggs inside wood where the larva parasitize boring insects.

Letter 2 – Giant Ichneumon

pictures of Giant Ichneumon?
Dear Bugman,
We snapped a couple of great pictures of a female Giant Ichneumon (genus megarhyssa macrurus) on a wall of our body shop in Akron, Ohio. My understanding it that it’s a type of parasitic wasp, and the long "tail" is actually the ovipositor that the wasp uses to insert its eggs deep into bark or soft wood. Does this sound correct? Do we have the correct bug? We thought it was odd that she was hanging around inside all day.
Thanks!
Judith & Kevin Mohr

Hi Judith and Kevin,
Your information and identification are both absolutely correct.

Letter 3 – Giant Ichneumon

WTF is this bug?
Hi, I’m from Denver, Colorado, and we dont get a lot of crazy insects on account of the dry-weather and cold and whatnot, but for some reason, I was out working in my backyard yesterday and I found this bizarre looking thing that I’d never seen before in my many years in the Rocky Mountains…and have NO idea what it is! Any ideas? (I have huge huge high-res photos if you’d like them for additional detail) Thanks a bunch!
Chris

Hi Chris,
We are sensing real domain potential with the “WTF is that Bug?” website. This is one of the Giant Ichneumons, probably Megarhyssa macrurus. The female deposits eggs with that stingerlike ovipositor and the young prey on wood boring insects.

Letter 4 – Giant Ichneumon

Can you identify this?
We recently found this bug in our yard while burning some trees that had blown down. It appeared they were laying eggs in the loose bark of one of the trees. It looked at if one was laying the eggs, and the other one might have been using the long "antenna" to fertilize the eggs.
Kathy

Hi Kathy,
Female Giant Ichneumons in the genus Megarhyssa use that long, stingerlike ovipositor to place eggs deep in wood that contains their food source, wood boring grubs. They are related to wasps, but do not sting and are harmless.

Letter 5 – Giant Ichneumon

Wood boring bug?
Dear Bugman,
I am interested in finding out what this bug is. Our local elementary school science teachers cannot name it. We found it in Northern Lower Michigan in the fall. Around the Lake City area. I have looked at ALL of the bugs on your website but have not seen this one. Please help.
Thank you.
Robert E.

Hi Robert,
Look again because we have an entire page devoted to Ichneumons. This is a Giant Ichneumon, Megarhyssa atrata. It is not a wood boring insect, but a parasite on wood boring grubs. The female, which you have photographed, uses her long ovipositor to lay eggs deep inside wood infested with horntails and other boring insects.

Letter 6 – Giant Ichneumon

pretty bug sitting on our screen door
I found this pretty bug sitting on our screen door this July in East-Central Illinois. Overall, it was about 5-6 inches in length. Any ideas what it was?
Thanks,
Kim

Hi Kim,
It is so refreshing that you find the Giant Ichneumon species in the genus Megarhyssa pretty. Usually people are horrified at the thought of getting stung. That long appendage is the female’s ovipositor and it is used to deposit eggs in wood infested by boring larvae and grubs. This is a beneficial insect.

Letter 7 – Giant Ichneumon

What’s this bug??
Hello! Can you please identify this tree bug for me? Last summer at our cottage in the Eastern Townships (Brome Lake), Canada…I found several of these bugs burrowing into one of my trees. The tree is hollowed in several places by woodpeckers. These particular flying bugs that have about 4 inch long triple tail end tenticles that burrow into the tree, (all 4 inches of their tail end tenticles into the tree, and I must say only in this particular tree). They may be about 2 inches in length, and I also see some smaller brownish types around, but they do not react in the same way. The larger ones that appear to be darker in color, have a tail end that engulfs, and fans out into a whitish colored fan, that may grow to about the size of a nickle. Once their tail end fan appears at its’ largest, they retract it and fly away. I have never seen this bug before, and have owned my cottage for the past 25 years. Can you help identify, and explain what this bug is? I hope my pictures will be good.
Thankyou,.
Diane O’Donnell

Hi Diane,
The Giant Ichneumon, Megarhyssa atrata, is a beneficial insect that lays eggs in wood infested by boring grubs.

Letter 8 – Giant Ichneumon

Bug pic
This was found on the wooded doorpost of our office door — in Washington Crossing (North of Phila.), PA
John

Hi John,
This is a Giant Ichneumon in the genus Megarhyssa. It doesn’t sting.

Letter 9 – Giant Ichneumon

Please help!
This awesome looking wasp-like insect was discovered on the window outside my house. I have searched your website, other websites, and several insect guides and cannot find anything like it. It somewhat resembles a mayfly and has three long whip-like tails protruding from its back section, but I’m pretty sure it’s not one. Can you help me identify this fascinating insect?
Thanks,
Andrea

Hi Andrea,
Nice collection. This is a Giant Ichneumon in the genus Megarhyssa.

Letter 10 – Giant Ichneumon

Bug in Kansas City
What is this bug? We are thinking either a crane fly or scorpion fly. Is it poisonous? Please let us know.
Thanks,
Bob Hamilton

Hi Bob,
The Giant Ichneumon, Megarhyssa atrata is neither poisonous, nor does it sting.

Letter 11 – Giant Ichneumon

What is it?
Hi "bugman"
We have seen this bug several times, however not until a week ago did we have a camera ready to photograph it. Can you help us to identify it? It is in the process of laying eggs, or so we believe. We can almost see through it and it appears to have a "rod" in its tail end coming right through and into the bark of the tree. Any help would be appreciated.
Thank you so much for your time.
Rose Dubay

Hi Rose
This is a Giant Ichneumon in the genus Megarhyssa, probably Megarhyssa macrurus. This is a female parasytic wasp that lays her eggs in the burrows of wood boring grubs. The Wasp cannot sting people and is beneficial.

Letter 12 – Giant Ichneumon

What is this bug?
My neighbor showed these to me and wanted to know what they are. He showed me a tree in his yard that has small round holes in it. The bark is falling off where the holes are and the tree is dying. Are the holes being made from these insects or another? Could it be that these insects are feeding off of another bug that is destroying his trees?
Awesome site,
Dan Shope

Hi Dan,
These insects are Giant Ichneumons in the genus Megarhyssa. They feed on the larvae of wood boring insects. The tree could have been dying on its own which attracted the boring insects, or it could have had an infestation of wood boring beetles or other insects that contributed to its demise. At any rate, once the wood borers were present, the Giant Ichneumons were attracted. These beneficial insects help to control the populations of more destructive insects, kepping the delicate balance of nature.

Letter 13 – Giant Ichneumon

what is this?
What the heck is this wasp-like creature? and will he bite/sting? He was hanging out on our house in southern Colorado. He is about 3 in. long, not including the (tail?).

This is one of the Giant Ichneumon species from the genus Megarhyssa. It is harmless despite the formidable looking ovipositor.

Letter 14 – Giant Ichneumon

I couldn’t find this one on your site.
Dear Bugman,
I would like to know what this bug is. My location is Sugar Land, Texas. The length of the two bricks total 6 inches. The 4 inch long needle like stinger is the most alarming part of the bug.
John

Hi John,
You have one of the Giant Ichneumons, Megarhyssa species. The female has a long ovipositor that she uses to lay eggs deep inside wood that is infested with wood boring grubs. They young Ichneumon feeds on the grubs. Though she is a wasp, the female Ichneumon doesn’t sting, despite the formidible looking “stinger” which is like an egg-laying syringe.

Letter 15 – Giant Ichneumon

What kind of insect is this?
Hello! I found this insect at my house located in Central PA. I think that it may be some sort of dragonfly. What is it?
Thanks!
Eileen

Hi Eileen,
Thanks for sending in the great photos of Megarhyssa atrata, the Giant Ichneumon. Your female wasp uses that long ovipositor to deposit eggs deep inside living trees. Her young seek out and devour boring insects like sawflies. Though it looks dangerous, she will not sting you, despite being a type of wasp.

Letter 16 – Giant Ichneumon

strange insect in my garden
My sons were in the garden and noticed this "yellow headed monster" – it seemed to have a long proboscis inserted into the base of our maple tree, and its abdomen slowly started turning from black to white, as if it were emptying itself into the tree. I used a stick and "encouraged" it to remove this from the tree, and the abdomen went back to black. There were actually three long black probosces coming from the end of the abdomen. Any ideas? Thank you very much. p.s. Is there anything I can or should do about this? a friend suggested injecting vinegar into the site where the eggs were likely laid. Would this work? Thank you.
Tara

Hi Tara,
We love your letter on so many levels, but especially for the interesting way you described the oviposition of a female Giant Ichneumon, Megarhyssa atrata. This is actually a beneficial insect. She is laying eggs in wood that has wood boring grubs. Her larva will consume the grubs and not harm your trees. She has an ovipositor, not a proboscis. We are also intrigued with the vinegar suggestion. Not sure, but is sounds as if vinegar might be effective in controlling some insect pests.

Letter 17 – Giant Ichneumon

hornet-wasp bug
Was about to cut a part of a maple tree down when i was face to face with 10 of these guys, was wondering if you might know what the are. the have long tails that stretch out 4”
Mark

Hi Mar,
This is a female Megarhyssa atrata, a Giant Ichneumon. She is ovipositing, meaning using that stingerlike ovipositor to lay eggs on wood boring grubs that are feeding on the dead and dying wood of your tree. The larval Ichneumon will feed on the wood boring grubs.

Letter 18 – Giant Ichneumon

Please help me figure this one out
Hi there.
My name is Kenneth. I was taking a bus home from niagara falls to London (ontario), me and my friend got laid over at the bus stop in "Burlington" (ontarip, not sure if the locations are going to help or not so yea.) but this gaint bug just fewl up and landed on the tree not even 2 fet away from me.. and it scared the crap outta me lol. I just wanted to know what kinda of bug it was. i’ll attach a copy of my picture here. (took the picture using my macro lens, so hopefully you can see it clearly) in the picture here. i really should of put something else in the shot just for scaling.. but i didnt think of it.. too scared lol. but the stinger (or what looks like a stinger :S ) was at least 6 inchs long. the body was about an inch and a half please if you could help me understand what this bug is. maybe next time i wont be soo scared of it. lol thanks. feel free to contact me at this address

Hi Kenneth,
While we understand your fear of the unknown insect with the six inch long stinger, we can assure you that this Giant Ichneumon is perfectly harmless. We believe this is Megarhyssa macrurus, but it might be another member of the genus. Your specimen is a female, as evidenced by her long ovipositor, not stinger. She oviposits her eggs deep inside dead and dying wood since the larvae feed on wood boring grubs. Through some complex sensory perception, she manages to locate the host grub for her larva and deposits the egg where larva will find host. It is not entirely clear if she oviposits directly onto the grub, or into the tunnel the grub has bored into the wood. We are currently researching the brilliant and interesting 17th Century naturalist and artist Maria Sibylla Merian in preparation for a lecture we will give next month at the Getty. Merian pursued her fascination with caterpillar metamorphosis to the Amazon jungles of Surinam in the year 1699. Her quest to document the wonders of the exotic new world on originated in Germany, when, as a child of thirteen, she began to illustrate insect metamorphosis, including all stages and food plants of the caterpillars she located in her garden. She produced work at a time when the scientific community still believed in Spontaneous Generation, and she could not figure out why some pupa, or date pits as she called them, developed into butterflies and moths while others produced wasps and flies. Flies like Tachnid Flies and wasps like Ichneumons and Braconids parasitize the larvae and pupae of other insects, resulting in the confusion that Merian encountered while trying to unravel the wonders of life on this planet (and beyond) by direct observation. While that is way more information than you requested, the bottom line is that to this day, we still understand so little about the world around us, and one careless decision just might be the straw that breaks the camel’s back, producing irreparable harm to our planet. While we believe that life will not be completely destroyed, that straw just might lead to mass species extinctions, including, perhaps, the human species. Thank you for taking the time to observe the world around you.

Letter 19 – Bug of the Month: August 2007 – Giant Ichneumons

bug??? Hi,
I was wondering what kind of bug this is. There were at least 30 of them on the tree at once. I am located in Grand Rapids MI. Thank you soooo much for your time!
Melissa

Megarhyssa atrata	Megarhyssa macrurus

Hi Melissa,
You have submitted photos of two different species of Giant Ichneumons. The black specimen with the yellow head is Megarhyssa atrata and the brown and yellow individual is Megarhyssa macrurus. Giant Ichneumons are beneficial insects, though they are often mistaken for wood wasps upon which they feed. The adult female Giant Ichneumon uses her formidable ovipositor to deposit eggs in wood infested with wood boring larvae of the Pigeon Horntail and other Wood Wasps. The young Ichneumon parasites the wood boring larva. We have gotten so many images of Giant Ichneumons this summer we have decided to make it the Bug of the Month for August.

Letter 20 – Giant Ichneumon

Is this rare to Minnesota?
Wed, Nov 19, 2008 at 7:35 AM
I photographed these in August in my backyard, I had never seen them before. I have learned, from the University of Minnesota and your website that they are megarhyssa atrata. They are beautiful. Can you tell me if these are rare to my area, or can I expect more of them in the future? Thank you so much for your help.
Anita, Plymouth MN
Plymouth, Minnesota

Hi Anita,
Your Giant Ichneumons, Megarhyssa atrata, do range in Minnesota and they are not uncommon.  the likelihood of seeing them in the future probably depends upon a food source.  The adult females in your photo are laying eggs in the wood of a tree that is infested with wood boring larvae, most likely those of the Pigeon Horntail.  As long as dead and dying wood is present and that wood is infested with the host insect, there will be a ready food supply for the Megarhyssa atrata and you will probably see the adults.

Letter 21 – Giant Ichneumon

Horse Hair Tail Insect
Sat, Jun 20, 2009 at 5:49 PM
These weird looking bugs are hanging around tree stumps, which have many holes in them. I don’t know if these insects made the holes or if they are trying to lay eggs in them, or get at the bugs in the dead stumps. The tail is almost like a strand of horse hair, about 4 inches long. The head, front legs and tentacles are bright yellow. It has a narrow body (black) about 1 1/2 inches in length and the wings are purple in color, 1 inch in length. As you can see in one of the pictures, the tail turns into a light green circular thing and the tail looks like it is rolled up in it. Then it will lose this thing and again have the horse hair like tail again. They also can fly. What the heck are these things?
Linda Mueller
St. Paul, Minnesota

Good Evening Linda,
You have Giant Ichneumons, Megarhyssa atrata, non-stinging relatives of wasps.  Giant Ichnuemons parasitize the larvae of wood boring insects like the Pigeon Horntail.  The female Giant Ichneumons locate the grubs deep inside the wood, and then use their stinger-like ovipositor to deposit an egg inside the tunnel inhabited by the larva.  When the egg hatches, the larval Giant Ichneumon locates the wood boring larva and parasitizes it. The holes you saw were probably produced when the wood boring larvae emerged as adults, or possibly by the Giant Ichneumon when it emerged.

Letter 22 – Giant Ichneumon

Wasp or Dragonfly?
July 19, 2009
While hiking around in the Umatilla National Forest near the Washington/Oregon border, the wife and I stumbled upon this little guy. Luckily the wings were still damp and it was unable to fly away. It was about 3-3 1/2 inches in length and as you can see it just seems exotic.
Peter H.
Umatilla National Forest about 25 miles south of Pomeroy WA

Hi Peter,
Our blood pressure is a bit high right now since we just got done posting our Sixth Nasty Reader Award.  We really wanted to send a nice response after dealing with that.  This is a Giant Ichneumon, most likely Megarhyssa nortoni, as evidenced by images posted to BugGuide.  Giant Ichneumons are non-stinging relatives of wasps.  Your photo is of a female whose lengthy ovipositor is barely visible in the photo.  The female Giant Ichneumon uses her lengthy ovipositor to deposit her eggs in dead and dying wood that is riddled with wood boring larvae.  The larval Giant Ichneumon then feeds on the wood boring insect.

Letter 23 – Giant Ichneumon

Wasp Style Insect Found in Ohio
July 27, 2009
Hello – Unfortunately I am not much of a bug expert, just a long distance boyfriend trying to see if my girlfriend and our new puppy have to be worried about getting stung by this bugger (no pun intended… well.. maybe a little)
This guy was found in a wooded area in a residential district surrounded by homes and larger lawns. They are usually found clumped together in groups of 4 to 5, and are not always active. When the pictures were taken they were barely stirred and did not fly around a lot at all. The biggest feature, although hard to see in the photos, is a whip-tail looking stinger perhaps that is honestly longer than the body, curling under the length of the insect. Please check the photos for more information. A name/identifier and any dangers it could cause to smaller animals would be great.
Cheers, Ryan L Montgomery, USAF
Dayton Ohio

Hi Ryan,
Your guy is a gal and she is a Giant Ichneumon, Megarhyssa atrata.  Though she is related to wasps, she is incapable of stinging, so she is harmless.  What appears to be a giant stinger is actually the ovipositor which the female Ichneumon uses to deposit her eggs inside dead or dying wood where the larval food, wood boring larvae, can be found.  Ichneumons are considered parasitic Hymenopterans.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Giant Ichneumon

What is this?
August 11, 2009
I saw this critter in North East Ohio. It was boring into a tree with its 4 or 5 inch tail…the body was maybe 2 to 3 inches long. What the heck is it?
Kenny
North Eastern Ohio

Hi Kenny,
You have spotted a Giant Ichneumon, Megarhyssa macrurus, in the process of ovipositing.  Giant Ichneumons are parasitoids whose larvae feed on the wood boring larvae of the Pigeon Horntail and other Wood Wasps.  The female Giant Ichneumon locates a wood boring larva and then uses her lengthy ovipositor to deposit her egg in the proximity of the wood boring larva. You can find more information on BugGuide.