Wasp With Long Tail May Be Ichneumon

Finding a large long tailed bug near your house is surely a cause for concern. However, its likely that the wasp with long tail may be ichneumon, a gentle giant with no intention or means to hurt you. Let’s learn more about these wasps below

If you see a giant black menacing-looking wasp with a long tail in the park, garden, or near a trail, it is most likely a black giant ichneumon wasp (Megarhyssa macrurus).

Despite their appearance, these wasps are actually benign and even beneficial to the garden. They are not aggressive and don’t bite humans.

These wasps are particularly famous for their long ovipositors, which many confuse for stingers, but are actually only useful for laying their eggs. 

The female ichneumon wasp bores a tunnel using her needle-like ovipositor into stumps of dead wood and lays her eggs on the larvae of pigeon horntail wood wasps.

When the egg hatches, it eats the host larvae and then pupates in the wood until it is time to fly out and reinitiate the process.

Wasp With Long Tail May Be Ichneumon

Do They Bite or Sting?

No, as we mentioned earlier, these long tailed wasps do not bite or sting. These wasps do not have stingers at all.

In fact, many people’s first reaction when they see them is that they are encountering a wasp with long stinger, but that’s not the case at all.

The females of this wasp species have five-inch long ovipositors, which are used to lay eggs. 

These ovipositors can bore through wood and can be deadly to the host they are parasitizing but are not useful against humans or other predators.

The poor males don’t even have the ovipositor!

Can They Spread Disease?

No, black giant ichneumon wasps do not spread any disease known to man. They are mostly harmless and typically don’t interact with humans at all.

Unless you specifically try to frighten them or handle them, they will show no interest in you. In fact, these flying bugs with long tails are actually beneficial to humans in many ways.

They help in removing wood wasps from your property, which can be a big nuisance since they attack your outdoor wood surfaces and leave behind holes, scratches, and dents.

Are They Harmful to Humans or Pets?

No, these wasps are not harmful in any way to humans or pets. Even though you might think that having a wasp with long tail near your home might be dangerous, there is absolutely nothing to worry about if you see one of them. 

They don’t live very long (just about 27 days), so there’s no need to make efforts to remove them, either.

Wasp With Long Tail May Be Ichneumon

Can They Get In The House?

It is unlikely that these wasps would fly into your house. They only hover around trees with dead wood since their purpose after emerging as adults are to mate and lay eggs.

Their larvae feed on the pigeon horntail wasp larvae, making sure to leave the essential body parts till the very end so that the meat remains fresh.

Since the larvae of these wasps with long tails pupate and overwinter inside the tree itself, they don’t have to take shelter in your home to protect themselves from cold weather.

During the summers, the adult wasp only sits on trees and doesn’t even need to make a nest.

How To Get Rid of Them?

If you see a giant ichneumon wasp in your garden or yard, there is absolutely no reason for you to remove it or get rid of it.

These bugs are not harmful to humans, they don’t bite or sting us, and they don’t feed on anything in your garden. 

Moreover, they help remove pigeon horntail wood wasps and other small insects from your yard, so they are beneficial to gardeners.

They don’t make nests like other wasps or bees and are solitary bugs, so you will never see a swarm of these bugs attacking you.

All in all, we suggest that you just let the wasp be. It will hopefully leave your garden for its final abode within a month, anyway.

Wasp With Long Tail May Be Ichneumon

Where Do They Lay Their Eggs?

Black giant ichneumon wasps are parasitoids. As we mentioned earlier, they like to lay eggs on the pigeon horntail wasp lava.

These larvae are usually found inside dead wood. The giant ichneumon female wasp searches for them using her long antennae, hoping to hear some vibration from the movement of the wood wasps’ babies.

When she is sure of it, this flying bug with long tail takes out her ovipositor and drills into the wood. Over the course of three to four hours, she is able to penetrate the wood precisely at the location where the wood wasps larvae are present.

Next, she injects these larvae with a venomous sting (don’t worry, their venom is not powerful enough for humans) and paralyzes them.

She then deposits her egg outside the larvae’s now paralyzed body, and after a few days, when the eggs hatch, the ichneumon larvae make a meal of the wood wasp larvae.

The egg-laying activity usually happens during the June to September months, but the larvae take their own sweet time to feed. They then pupate and overwinter, spending the winter season inside their cocoons.

In the summer or spring months, they emerge as adult ichneumon wasps and restart the process.

Wasp With Long Tail May Be Ichneumon

What Are They Attracted To?

There is one sure-shot way to attract these wasps with long stingers – to have dead wood around the house. 

Since their primary purpose as adult wasps is to reproduce, these guys are always on the lookout for dead wood bearing the larvae of pigeon horntail wood wasps.

Their natural habitat is deciduous forests, but rapid deforestation by human activity has caused them also to inhabit some areas where humans are living, such as parks and gardens.

Readers’ Mail

Over the years, we have received dozens of emails from our readers who have seen these beautiful but fearsome long stinger wasps (which turned out not to be a stinger at all!).

Let’s revisit some of these letters below.

Letter 1 – Giant Ichneumon

 

Long tailed bug
May 27, 2010
Yellow head and antenae, very long tail. WIngs (two) and rather clumsy. Exploring pansies in planter and will fall off.
M. Temple
New England – Medfield MA

Giant Ichneumon

Dear M. Temple,
Many people are shocked or frightened when they encounter a Giant Ichneumon, Megarhyssa atrata, for the first time.  The Giant Ichneumon is a parasitoid insect that preys upon the wood boring larvae of another non-stinging wasp relative, the Pigeon Horntail.  A female Giant Ichneumon, like the one in your photo, locates a wood boring Horntail larva and then drills into the stump or trunk with her five inch ovipositor.  Male Giant Ichneumons do not have an ovipositor.

Letter 2 – Squashed Giant Ichneumon

 

large wasp-type bug with long ‘tail’
November 17, 2009
This bug came in when we opened our back door one evening a few nights ago. Sorry, my husband squished it. The envelope it’s sitting on is a business-sized (10 inch) envelope for size reference. It’s very dark or black with a long jointed looking body, black wings and the really long tail that totally creeps me out. πŸ™‚
Scaredy Cat
North Texas/DFW

Squashed Giant Ichneumon
Squashed Giant Ichneumon

Dear Scaredy Cat,
This is a female Giant Ichneumon, Megarhyssa atrata, and she is perfectly harmless.  The tail, though it looks like a stinger, is actually an ovipositor.  With her long ovipositor, the female Giant Ichneumon drills into diseased wood to lay an egg on the larva of a wood boring insect, the Pigeon Horntail.

after reading your site for over an hour the night that I posted, I learned the purpose of that long tail thingy. Wish we wouldn’t have squished her. It was fear-induced carnage. πŸ˜‰ With 3 cats and 2 children she probably wouldn’t have lasted long anyway!
Thanks for responding and confirming what I found on your site. We also have great photos of a wooly caterpiller that looks like what the Japanese Monster Mothra was based upon. πŸ™‚ Can we just submit photos even when we know what the bug is?
Kim

Hi Kim,
You may submit photos, but please use our question form and provide your location.  Also, please do not submit more than one species of insect per letter.  We are very happy to hear you were able to make your identification without our assistance.

Authors

  • Daniel Marlos

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

34 thoughts on “Wasp With Long Tail May Be Ichneumon”

  1. We were walking home from my neighbors house when suddenly a huge wasp-looking insect flew right in front of my face! It really reminded me of a stingray because of the long tail. It landed on the tree near by, so I went to look at it. But when I walked away it6 came after me like it was going to sting me!!! I think that I saw a Giant Ichneumon. I had never seen a bug like that before. I live in South Dakota.

    Reply
  2. I saw about ten of these on a dead elm tree. They looked like they were having some very deep sex with the tree. I tokd my neighbor he was going to have a nightmare about one with a fifteen foot ovipositor breaking his window and going through his ear, waking to a slight headache, then one day his head would explode with the brain consuming larvae. Sorry-my brain hurts somehow. Thanks for the id… Oh, this is Minnesota-twin cities.

    Reply
  3. Today at 8:56 there was one in my house on my ceiling. First time I’ve ever seen one. I thought it was a wasp with human hair hanging from the back when I realized it was attached. Caught it, and threw it outside. Very VERY glad to know it is harmless.
    Oklahoma OK

    Reply
  4. Today at 8:56 there was one in my house on my ceiling. First time I’ve ever seen one. I thought it was a wasp with human hair hanging from the back when I realized it was attached. Caught it, and threw it outside. Very VERY glad to know it is harmless.
    Oklahoma OK

    Reply
  5. A coworker brought a half dead one to me in a box never seen it before in my life glad i found this article now i know

    Reply
  6. Had one flying around the front porch tonight. What a cool looking bug! I wouldn’t describe it as wasp like, though. It resembles a May Fly, but in black with a long tail. I suspected the “tail” may be some reproductive structure, and it is! Very impressive lol

    Reply
  7. Southern Illinois 8-8-17. I have lived in the country most of my 60 years and saw this bug today for the first time ever. Glad to come by your site here. She was on the outside of the screen but scary enough I might have killed her inside. Now I know not to. πŸ™‚

    Reply
  8. today I found one in my pool when i was cleaning lets just say i was not so happy to see it . i did not want to kill it so i want on google and typed in black bug with long tail thing . thank you now i know its not so bad so i set it free i am so glad to have found this website .

    Reply
  9. We live in Southern Indiana. My sons bedroom has an exit door to the back yard which was open & one of these flew into his room while he was on his computer. Yes, he killed it then yelled for me to come see something. OMG it was big with this very long like tentacle hanging out of the rear of his body. He didn’t know they were harmless or he wouldn’t have killed it. First time any of us in the house saw something like that. It sure was scary looking.

    Reply
    • I woke up to one laying in the bottom of my fridge today!! Took a pic, grabbed a broom & dustpan, put it outside on a log. It was slightly moving, probably warming up. Checked on it 5 min later on the concrete, lifting its rear end toward its head a few times. Took 2 more pics, then it flew toward me, I yelped and ran inside to take off my clothes and shake like a Spanish dancer!πŸ˜† How and why did it get in my fridge?!!

      Reply
  10. We saw one at work yesterday flying around the warehouse. Nobody knew what it was. Now I know its harmless. Knoxville Tn.

    Reply
  11. We have a similar bug but it gets in behind our vinyl siding so we think it is building a nest. It always goes in the same vinyl siding in a corner and it has a very long thin thing attached to it rear. It does not bother us as we are about 3 feet from the vinyl where it enters. We are sitting on our deck and watch it go into the vinyl. Where it goes after it is under the vinyl we don’t know and we are very concern. What should we do kill it??

    our deck. should we be Leary that it might not be one of these bugs you all are talking about. we are in ohio

    Reply
  12. We have a similar bug but it gets in behind our vinyl siding so we think it is building a nest. It always goes in the same vinyl siding in a corner and it has a very long thin thing attached to it rear. It does not bother us as we are about 3 feet from the vinyl where it enters. We are sitting on our deck and watch it go into the vinyl. Where it goes after it is under the vinyl we don’t know and we are very concern. What should we do kill it??

    our deck. should we be Leary that it might not be one of these bugs you all are talking about. we are in ohio

    Reply
  13. I found one in our Linden tree. I didn’t bother it and took a couple pictures of it. We are in west central Nebraska.

    Reply
  14. I live in Olympia, WA and I just captured (in a jar) what I believe to be a Western Giant Ichy. Based on this page, I am under the impression that I should let it live, and release it.

    Reply
  15. the one we saw in Greenwich, London was thicker than your pictures and trailing long thin black tail? as it flew up to the mezzanine where it landed on the side of exposed white beam with tail hanging beneath took my eye off for a second and it seems to have left. will sleep with door closed tonight, as it honestly freaks me out stinger or no stinger.thanks for the reassurance. Are they kown to be migrating?

    Reply
  16. Just saw one of these in my kitchen, but I live in Central Scotland 🀣 there are some large trees across the street but we are in a town centre beside a main road so feels very out of place!

    Reply

Leave a Comment