Wood wasps bore holes in decaying wood and deposit their eggs inside. They have long, stinger-like appendages. But do wood wasps sting, or is the appendage ineffectual? Let’s find out.
Wood Wasps are large insects that belong to the Siricidae family. They are non-stinging insects but create a buzzing when they fly, which may be annoying to human existence.
Also referred to as horntail wasps, they are usually found around coniferous trees that are freshly cut or burnt. In this article, we talk more about these intriguing creatures.
What Are Wood Wasps?
Wood wasps belong to the Siricidae family, and there are close to 500 species of these wasps.
They are mostly solitary insects and are usually found near coniferous plantations. They prefer to live in or lay eggs in trees that are freshly cut, recently burnt, or have decaying wood.
Their females lay eggs using a very unique method. They use their needle-like ovipositor to thread the wood until it is completely inside and then lay their eggs.
In fact, one of the parasite wasps, ichneumons, uses the same trick to place their larvae on top of wood wasp larvae. The ichneumon’s larvae then feed on the wood wasp ones.
Most of the time, wood wasps are non-threatening to human beings. They have an ovipositor, not a stinger, so they cannot sting.
Moreover, they spend most of their time in and around trees and woods. However, they may be annoying to some since they create a buzzing sound when they fly.
Wood wasps can be found all across the US, but they are abundant in Oregon, California, and Washington.
What Do They Look Like?
Wood wasps are large insects with bodies that are about half an inch to an inch long. Adult wasps, both male and female, have barrel-shaped bodies.
They are usually colored in dark shades, like black or metallic blue. Sometimes, they exhibit a combination of black, red, and yellow.
The only difference between the male and female wood wasps is that the latter has a stinger or ovipositor, which she uses to lay eggs in the bark of the trees.
The ovipositor is strictly used to lay eggs only and, despite its appearance, does not work as a stinger.
The ovipositor makes the female appear larger than her male counterpart. The female wood wasp looks quite intimidating due to her large size.
One more thing that separates female wood wasps from males is that they have thicker waists.
Do They Sting?
While many species of wasps sting, wood wasps are different; they cannot sting.
However, they can surely be a nuisance since they may make holes in the wooden exteriors of your home.
Places such as wooden boards, patios, decks, and fences are at risk of a wood wasp attack. If the wood is moist and decaying, the risk goes up even further.
Wood wasps also buzz when they fly, which can seem annoying to many humans.
In case you have a wood wasp living in your house timber, you will be able to recognize this sound from a distance.
Are They Poisonous or Venomous?
Wood wasps are neither poisonous nor venomous. They cannot even sting. Their females have long ovipositors only for dissecting the wood and inserting their eggs in tree bark.
Since wood wasps don’t sting humans, no allergic reactions may happen due to the bite of other parasitic wasps.
Are They Harmful to Humans?
Unlike bees or paper wasps, wood wasps are wood-boring insects and spend most of their life cycle in and around their nest.
They are usually non-aggressive because they are mostly solitary wasps and don’t have a nesting colony to defend.
However, they may create other types of nuisance, such as damaging the wooden areas of your house.
What Damage Do They Cause?
The holes drilled by the female to lay her eggs can severely damage wooden floors, roofs, fences, and other areas.
Moreover, the adults introduce yeast, bacteria, and fungi to the wood to soften it. This allows the larvae to chew on the softer wood for food, helping it grow quickly.
The chewing habit of the emerging wood wasp may leave even larger holes in the wood’s interior. It is important to keep your wooden surfaces painted, polished and varnished to avoid this damage.
How Do They Enter Homes?
If unused firewood is in your home for a long time, it may have turned into wasp nests. Wood wasps might find it and lay their eggs inside since firewood starts decaying after some time.
It is important to ensure that the wood in your yard is free from wood wasp infestation. You can use a good brand of insect repellent to get rid of larvae or adult wasps.
Frequently Asked Questions
Are wood wasps aggressive?
No, wood wasps are non-threatening insects that usually spend their lives in and around dying or burnt trees.
Since these are solitary insects, they don’t have a reason to become aggressive. However, they may cause damage to the wooden items in your homes and, thus, are a nuisance.
What is the most aggressive wasp?
The most aggressive wasps are the yellow jacket wasp, the cicada killer wasp, and the paper wasp.
All of these wasps are territorial and can sting not once but multiple times. Their stings can leave a very painful bite, along with a rash.
People allergic to wasp stings can even go into anaphylactic shock, especially if they get multiple stings. Such people may require immediate medical attention.
It is best to maintain a safe distance from wood wasps.
What time of day are wasps most active?
Most wasp species remain active in the middle of the day. Around this time, they leave their nest and fly around looking for nectar.
They also hunt during this time to get prey for their larvae. They prefer warm weather and return to their nest in the evening.
What are the most painful wasps?
When it comes to the wasp family, even bees sting quite harshly. However, the sting of a
Tarantula Hawk Wasp is described as a blinding electric shock in the Schmidt pain index. This insect gets the highest pain rating of all.
Wrap Up
We hope this article helped you learn a thing or two about wood wasps and how they cannot sting but can still cause trouble for human beings.
Wood wasps are non-threatening and usually live alone, so you might not have to worry too much about them. However, if you find several of them flying around, it’s time to call a pest management professional.
Also, always keep your wooden exterior painted and in good shape because wood wasps can nest in them. Thank you for reading.
Reader Emails
There are several varieties of wood wasps, and while we have given a general description above, each has its own peculiarities.
The emails from our readers below depict the amazing diversity of wood wasps. Please do go through!
Letter 1 – Wood Wasp
Hi there Bugman!
I came across this pretty, 2.5 – 3.0 cm long shiny gunmetal blue wasp with white banding on his legs while hiking in the Oregon Mt Hood Wilderness. I’m guessing he’s a Mud Dauber . . . . ???? But what type?
Peter
Hi Peter,
This is a Wood Wasp in the genus Urocerus. It matches an unidentified mounted specimen on BugGuide that might be Urocerus albicornis.
Update: Urocerus albicornus
(08/03/2007) Corrections on some ID’s
Dear Bugman,
Today I found a very eye-catching specimen of Urocerus Albicornis, the White-horned Horntail, wandering around on a Douglas Fir in extreme NW Washington State (near Ferndale) and laying eggs. I didn’t know what it was, but I captured it in a very high-tech device (empty paper soda cup courtesy of Burger King!) and brought it home, and after doing a little web-research, found out that it was the critter mentioned above. Actually, it was your website that really helped me make the leap forward finally – I wasn’t getting very far on any of the other so-called “identification” sites. So anyway, after I verified what it was, I tried to get some more information about it, but there doesn’t appear to be very much other than a very very few pictures. Almost NO information to speak of online. However, in the course of my ferreting around I finally came back to your site, and found several other pictures of this very dapper bug. But it looks like they are mis-identified, so I wanted to let you know. In response to the posting by Devon on 7/22/05, you state that it is a “Smoky Horntail,” and in response to a posting on 7/28/07 by Peter, it was ID’d as a “Wood Wasp…might be Urocerus Albicornis.” There were also several other postings that look very much like this bug, only the wings are more rust-colored – these are ID’d as Urocerus Californicus. (9/12/06 by Annie and one other, I don’t remember the date/poster though). I do have to apologize for not taking a picture of it for you guys before I released it, it was a real beauty. I’m glad I didn’t kill it though. … Also, must say, GREAT SITE!!!! Totally fascinating, to say the least. I spent WAY more time browsing around looking at all the cool bugs than the time I needed to find out about the Horntails. Two thumbs up!
Sean in Ferndale, Washington
Letter 2 – Wood Wasp, but how did it die???
July 25, 2009
I found this huge wasp-looking insect in my car, it is over an inch long and has a pure black body, and yellow bands on its legs. It has a huge thick stinger, I have never seen this insect before and would like to know what it is.
Lauren B.
Canada, British Columbia
Hi Lauren,
This is a Wood Wasp in the genus Urocerus, probably Urocerus albicornis based on images posted to BugGuide. Your Wood Wasp may look fierce, but she cannot sting, not only because she is dead, but because what looks like a stinger is actually the ovipositor for laying eggs within wood.
Letter 3 – Giant Wood Wasp
August 10, 2009
Just got back from a camping trip in Teller County Colorado and this bug landed on my leg. I have searched high and low on the web for pics of this insect.
Please help, Thanks Jon and Family
Colorado
Dear Jon and Family,
This is a Giant Wood Wasp, Urocerus gigas. It is also called the Greater Horntail Wasp or the Yellow Horned Horntail. According to BugGuide: “Range Introduced, originally from Europe and Asia. Habitat Attacks five or more genera of Pinaceae Remarks It tunnels in wood. One of the most dangerous pests of conifers.“ We will be tagging your post as an Invasive Exotic.
Correction: August 12, 2009
Not an invasive exotic wood wasp
Daniel
I was certain that U. gigas the exotic form has yet to be established here in the US. Upon discussion with our entomologist he is positive it is Urocerus gigas flavicornis (Fabricius) which is a native subspecies. Colorado is just one of the states that it can be found. You had me worried there for a minute. Our cups runith over with exotics as it is like Sirex noctillio. Great work as always and glad to see you folks have links to get in touch with the proper agencies that handle exotic invasive pests. I encourage your readers to become aware of exotic invasive pests, report new finds and help protect our resources.
Can’t wait to see your book
Thanks
Brian
Brian.Sullivan@aphis.usda.gov
Letter 4 – California Wood Wasp
August 17, 2009
We live in Western Washington State, and we were just remodeling our new house that we bought which is located in a very wooded area. We had all the doors and windows open while working. Two of these insects flew in and my husband said they were very aggressive. He said they were going after him trying to attack. I’ve been trying to research what kind of insect it is, but can’t find an exact match. It looks a little like the pictures I’ve seen of wood wasps or horntails, but I’m not sure. It was about 2 in long! Do you have a better idea of what this is?
Laura
Covington, Washington
Hi Laura,
We are exerting a bit of creative license and calling your native insect, Urocerus californicus, by the common name California Wood Wasp, There is only minimal information posted on the information page for this species on BugGuide, but Eric Eaton has the following information on an individual posting on BugGuide: “It is indeed a female U. californicus (orange wings, all-black abdomen). I’m envious. In all my years in Oregon I never once saw one of these alive. They must be like buprestids: emerge briefly in large numbers such that if you aren’t in the neighborhood that day, you would never know they existed:-)“ Wood Wasps cannot sting, and what appears to be a stinger is the female’s ovipositor.
Letter 5 – Wood Wasp from Alaska
Location: Southcentral Alaska, Hillside Anchorage AK
August 5, 2010 9:17 pm
These were flying around outside my garage, and I’ve seen them at my cabin, around 50 miles away as well. Any help would be appreciated in identifying them, as I do not know if they eat rotten wood, other animals, or ??. Thank you in advance.
Aaron
Hi Aaron,
This appears to be a Giant Wood Wasp, Urocerus gigas, a species introduced from Eurasia. According to BugGuide: “It tunnels in wood. One of the most dangerous pests of conifers” and it “Attacks five or more genera of Pinaceae.” It is also pictured on the Invasive.org website. It is also pictured on the Wood Boring Insects of Alaska website. There is also a native subspecies. We are seeking assistance regarding if this individual is native or introduced.
Correction thanks to Brian Sullivan of APHIS
Good to hear from you Daniel.
Yes I am still with APHIS.
The native subspecies Urocerus gigas flavicoris (Fabricius) does occur in Alaska.
Distribution: Labrador to Alaska, south to New Hampshire, Colorado, New Mexico, Arizona, and California.
Looks like a fine female.
I am always interested in possible exotics but can totally understand the direct contacting.
Keep up the good work as always
Brian
So, this individual is native and not the introduced subspecies?
Yes, it appears to be the case of a native.
Matches up with the guide I used for a fast ID.
I am getting ready to go on a much needed vacation and trying to clear my plate but make sure I looked it up real quick for you.
Brian Sullivan
Plant Health Safeguarding Specialist
APHIS
Letter 6 – PIgeon Horntail
Location: Northern Virginia
August 12, 2011 6:16 pm
We found this wasp outside of my parents home in Northern Virginia (Stafford). It was about 7 cm long with a 1.5cm stinger. The wings were iridescent blue. What kind of wasp is this?? I’ve never seen this kind of insect in California and hope to keep it that way!
Signature: Freaked out in Cali
Dear Freaked out in Cali,
You encountered a Pigeon Horntail, Tremex columba. Despite its fearsome appearance, it is perfectly harmless, and what you have mistaken for a stinger is actually the ovipositor that the female uses to deposit her eggs under the bark of trees with compromised health. The Pigeon Horntail is a Wood Wasp and the larvae bore in wood. The Pigeon Horntail is the host insect to another fearsome nonstinging wasp relative, the Giant Ichneumons in the genus Megarhyssa, which parasitizes the larvae using an ovipositor that can be five inches long. Stinging insects like bees and wasps sting with an ovipositor that is modified for defensive purposes. California has its own California Wood Wasp, Urocerus californicus, however, it is generally found in wooded areas, not in urban environments.
Letter 7 – Giant Wood Wasp
Location: central alberta canada
September 13, 2011 12:25 am
Hi there! My name is Rik.I live in kamloops BC canada,and have been working in Hinton Alberta Canada.On sept 12th 5pm i had gone into a bank whereby I had noticed a rather large insect on the inside window ledge.The insect was about 3 inches in length..i wonder what it is? Thank you …rik
Signature: rik in alberta canada
Hi rik,
This is a Giant Wood Wasp, Urocerus gigas, a species that is found in Eurasia as well as North America. What appears to be a stinger is actually an ovipositor. Because the larvae are wood borers, they can be spread and introduced to new locations by the shipping of wood products. See BugGuide for additional information.
Letter 8 – Wood Wasp
Location: Sonoma County, CA
September 23, 2012 10:25 pm
Howdy Bugman,
I run a small bandsaw mill unprofessionally and am current building a small house with it. I’m working on siding now out of a redwood that I dropped a year and a half ago and I kept running into these half pupated whatsits with creepy long legs. I thought they were Old House Borers but their legs looked too long for a beetles and also adding to the trouble was I kept beheading them with the saw which I’m sure you understand makes identification difficult. Finally uncovered this rather large metallic looking wasp that I miraculously missed with the saw. I dug it out and it sluggishly wandered around and I took a not so clear picture. I thought about killing it but if I spend a few minutes with an insect or arachnid even if they give me the heeby jeebies I feel bad and put them somewhere out of harms way. In this case I stuck it over on the scary old circular mill with removeable teeth. A little while later I saw it flying around and busily landing on things. Sin ce fall is fast approaching is this guy (gal?) going to make it or was it planning on overwintering in my siding?
Signature: best to all, Erik
Hi Erik,
This is some species of Wood Wasp or Horntail in the family Siricidae, and since you found it in redwood and redwood is a conifer, it is most likely in the subfamily Siricinae. There are only two genera listed on BugGuide, and we are having a problem identifying this to the species level. We will try sending the image to Eric Eaton to see if he can provide anything more specific. Your letter was filled with helpful information on the habits of Wood Wasps and Horntails. We also located this very informative posting from the Bohart Museum of Entomology at UC Davis.
Eric Eaton Responds with some surprising news
Daniel:
This really is a great story. Ok, from what I can gather, the only species of horntail known to infest redwoods in California is Sirex areolatus, and I reach that conclusion with the help of a very recent online reference:
http://www.fs.fed.us/foresthealth/technology/pdfs/GuideSiricidWoodwasps.pdf
Still, the ovipositor in this female specimen is very long. I’d like to forward this e-mail to two of the authors of the above paper, whom I know from prior correspondence. There is always the possibility I’m wrong, or that this is a new species, or an introduced species from elsewhere….
Lastly, with Erik’s permission, I’d like to use his image and story in a blog post about this species. I’d need his last name to assign proper credit, of course.
Eric
Hi,
Thank you so much for the identification I am fascinated by just about everything and enjoy learning more about my neck of the woods. Not actually my neck of the woods but I work there and that’s close enough. Just to be clear, I only thought about killing it because I was afraid it would generate future generations of wasps in my lumber. However upon reading that UC Davis article I understand they don’t infest or re-infest finished structures. This will learn me to get my butt in gear when I cut trees! Quite a spectacular wasp I’m glad I can say I didn’t kill it.
Thanks again,
Right, as for Eric’s request yes by all means. If it’s any more help, the larvae were found only in the sapwood of the redwood while the pupating ones and the adult were just in the surface of heartwood.
Best to all,
Erik Dolgushkin
Letter 9 – Giant Wood Wasp from the UK
Location: Nr Manchester, UK
August 3, 2014 12:46 pm
Hi there,
We live in the north west of England, near to Manchester and found this insect in our garden. It’s like nothing we’ve ever seen before. It measured about 3″ long. Can you identify it?
Signature: Best wishes, Fi
Dear Fi,
This is a Giant Wood Wasp, Uroceras gigas, and according to the Pottery Museum website: “Flight period: May – August. The large size and black and yellow colouration mean that this ‘wasp’ causes more than a few scares, but it is not a wasp at all, it is a sawfly and completely harmless. The large ‘sting’ is in fact the ovipositor, which is used to lay eggs (and gives it the alternative name of horntail). Most often seen in coniferous woodland. Common in Staffordshire. “
Letter 10 – Wood Wasp “stings” man in England
Location: North Yorkshire England
August 6, 2014 2:25 pm
Hi I was at work today putting up a fence when I felt a pain in my leg. I looked and was not sure what it was I knocked it away and in doing so unfortunately killed the insect. It had however stung me and it is incredibly painful even now 10 hours later. I am from the north east of England and have never seen such a creature please help me identify it!
Signature: James Rowe
Dear James,
This is indeed a Great Wood Wasp, and we are quite surprised to learn of your experience. According to UK Safari: “The female (above) has a long pointed tube at the back of her body, and this is often mistaken for a stinging organ. In fact it’s an ovipositor, which she uses to lay her eggs in the trunks of coniferous trees. Despite their appearance, these insects are quite harmless.” Knowing that and also knowing that the female lays her eggs beneath the surface of the bark of a tree, we believe it is entirely possible that this Great Wood Wasp mistook your leg for a conifer, and tried to lay eggs. Do you use pine scented soap? We do not believe she was trying to sting you. It is also possible that she used her powerful mandibles to nibble at your leg.
Dear Daniel,
Thank you for your speedy and informative response. This is indeed very likely as I was at the time building a fence using pine timber and it is very possible that the timber would have come into contact with my leg. There is in all 5 “sting” marks on my leg so it is possible that she has had a nibble. It is rather swollen and painful. What could this be? It does feel like a general bee/wasp sting. Could she have laid her eggs?
Many Thanks,
James Rowe
Hi again James,
This is quite perplexing and contrary to all we have read, so we are tagging this posting as a mystery. We suppose if you were jabbed with her ovipositor accidentally, it is also possible that she deposited eggs. Unless you have a wooden leg, you shouldn’t have much to worry about, however, as we are not medical doctors, should any irritation persist, you might want to seek medical attention.
Eric Eaton Concurs
Daniel:
I would concur with your assessment, except I doubt she would have laid eggs. After five attempts she may have concluded “this is not a tree.” In any event, I agree he should seek medical attention if symptoms persist or get worse.
Eric
Letter 11 – Wood Wasp from Ireland
Location: Ireland
July 16, 2016 12:24 pm
Hi,I’ve seen only one of these guys before. It’s maybe 1-2 inches long,as thick as a pen and the rest is in the picture. Would love to know what it is!! I thought it liked a bit like a fat mayfly
Signature: Thankyou
This is a Wood Wasp or Horntail, Urocerus gigas, and according to the Irish site Gardening.ie: “Wood wasps, also called horntails, are pretty scary insects. They’re large, they’re fast and noisy fliers, they come in yellow and black warning colours and they have what looks like a ferocious stinger on their rear ends. But, although they’re doing their best to frighten you off, they’re completely harmless. ” According to GeoGraph: ” It does not sting; the feature which gives rise to its common name is an ovipositor, used to lay eggs in coniferous wood.”
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