Cottonwood Borer Poisonous: Essential Facts Unveiled

The cottonwood borer is a type of longhorn beetle known for damaging cottonwood, poplars, and willow trees. These beetles are large and robust, with black antennae that can be as long or even longer than their bodies. Adult beetles can often be found on and around host plants during the summer months, when they are most active.

Larval feeding is the primary cause of damage to trees, as they hollow out, partially sever, or girdle them at or slightly below the root collar. This can lead to breakage and ultimately the death of a tree. While the cottonwood borer can wreak havoc on trees, it’s important to know whether they pose a threat to humans as well.

Cottonwood Borer Identification

Description and Size

The Cottonwood borer is a type of longhorn beetle typically found in North America. This insect can be a serious pest, especially for cottonwood, poplar, and willow trees. Adult Cottonwood borers are large, with a size ranging from about 1 to 2 inches in length. Their larval stage is characterized by legless, round-headed borers that can grow up to 1.5 inches long ¹.

Color

Adult Cottonwood borers have a distinct black and white coloration pattern. The black and white coloration is often mistaken for the Asian longhorn beetle due to their similarities ².

Antennae and White Hairs

Key features of the Cottonwood borer include its black antennae and prominent patches of white hair. These characteristics can be useful in distinguishing the Cottonwood borer from other species of beetles.

In summary, identifying the Cottonwood borer can be done through its physical features such as size, color patterns, black antennae, and white hairs.

Life Cycle and Habitat

Eggs

The cottonwood borer breeds in the bases and roots of living cottonwood, poplars, and willows. Females lay their eggs in the bark crevices of these trees.

Larvae

Once the eggs hatch, the larvae begin feeding on the wood. This stage is where they cause the most damage to trees, especially young ones.

Pupation

After they’ve fed and grown, the larvae pupate within the tree. This process takes place in the second spring, resulting in a two-year life cycle. ¹

Adult Stage

Upon reaching adulthood, the cottonwood borer emerges from the tree. These beetles are large, being 1¼ inches long, and possess black antennae that can be as long or even longer than their bodies ². They can be found on and around host plants during the summer season.

The cottonwood borer is primarily found in North America, with widespread infestations occurring in the United States. They tend to prefer the habitat provided by cottonwood, poplar, and willow trees.

Characteristics of the cottonwood borer include:

• Breeding in the bases and roots of trees
• Preferring cottonwood, poplars, and willows as host plants
• Having black antennae as long or longer than their bodies

Remember, it’s important to recognize and manage cottonwood borer infestations to protect the health of your trees.

Host Trees and Damage

Cottonwood Trees

Cottonwood borers mainly target cottonwood trees. They can cause significant damage during their larval stages.

• Damage includes: girdling, trunk weakening
• Infested trees may have: dead branches, discolored leaves

Willows and Poplars

In addition to cottonwoods, these beetles also infest willows and poplars.

• Infestation signs: similar to cottonwood trees
• Damage examples: reduced growth, broken tree trunks

Symptoms of Infestation

Infestations may lead to various symptoms. Here’s a comparison:

• Girdling occurs at or slightly below the root collar
• Adult beetles feed on tree bark and tender shoots
• Larvae mainly cause damage as they burrow into trunks and branches

By keeping an eye out for these symptoms, you can detect infestations early and take proper action.

Control and Management

Prevention

Preventing cottonwood borer infestations begins with proper tree care. Healthy trees are less susceptible to attack, so consider the following steps:

• Fertilization: Maintaining adequate nutrient levels with proper fertilizer application
• Irrigation: Providing supplemental water during dry periods
• Mulching: Applying mulches around the tree base to conserve moisture and regulate soil temperatures

It is also essential to identify and destroy infested trees, as they may act as a breeding ground for more pests.

Chemical Control

If infestations are severe, chemical treatments may be necessary:

• Permethrin: A commonly used insecticide for controlling cottonwood borer
• *Note: Consider using safer chemicals, as some insecticides can harm non-target organisms

Keep in mind that chemical control should always be a last resort.

Non-Chemical Methods

There are alternative strategies to manage cottonwood borers without using chemicals:

• Manual removal: Hand-picking adults and larvae from trees, if populations are small
• Traps: Using pheromone traps to capture and monitor adult borers

It is important to know that these methods may only provide limited control and should be combined with preventative measures for the best results.

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 – Cottonwood Borer

Interesting Bug
Location: 41st & Riverside, Tulsa, OK 74105
June 23, 2011 10:46 pm
I saw this bug at the park today on the playground equipment. It would fly when spooked or provoked. Otherwise it preferred to walk. I just wondered if it was posionous since it was at a park and there were several children around. I’ve never seen anything like it before.
Thank you so much!
Carrie Kreber
Signature: Thanks!

Hi Carrie,
We saw from your subsequent email that you already self identified your Cottonwood Borer, and we are happy to hear that.  We also think this is such a beautiful photograph that we want to post it for the benefit of our readers.  Cottonwood Borers do not pose any threat to children, though they do have very powerful mandibles and they might produce a painful bite if carelessly handled.  The bite may even draw blood.

Daniel,
Post away-I don’t mind…I thought it was the oddest bug until I saw your site last night and started searching for my bug-then I saw some of the oddest bugs! 🙂 lol
Have a great weekend and feel free to post.
Carrie

Letter 2 – Cottonwood Borer

not sure what this bug is!
Location: Mansfield, TX
May 27, 2011 2:19 pm
I live in Mansfield tx and I was on the play ground with my class when I saw this bug! It was pretty big & I have no idea what it is or if it’s dangerous.
Signature: thanks so much!

The mandibles of the Cottonwood Borer are quite strong, and it is possible that they might deliver a painful nip if the insect is carelessly handled, but the Cottonwood Borer is not considered to be dangerous.

Letter 3 – Cottonwood Borer

Found this bug in our front yard
Can you help us identify this critter that we found in our front yard? We live in Wichita KS and just took the picture today.
Linda Riley
wichita KS

Hi Linda,
Your beetle is a Cottonwood Borer, Plectrodera scalator.

Letter 4 – Cottonwood Borer

flying white beetle ?
Bugman, Here’s a neat looking insect I came across today. I found it crawling on my van. It’s body was nearly 2 inches long. I’ve never seen one of these before here in Illinois. From what I’ve found on the web, the body shape is like an Asian longhorn beetle, but the white coloring doesn’t match. Any ideas?
Mike

Hi Mike,
Nice photo of a Cottonwood Borer, Plectrodera scalator. Larvae bore in cottonwood and poplar trees. Adults fly from July to September and yours is the first photo of the year. I’m sure we will get more of this beautiful native beetle.

Letter 5 – Cottonwood Borer

What’s this bug (see attached photos)
Dear Bug Man,
A year or so ago I found this monster crawling on the side of my house (in Bedford, Texas). It’s 1.5" body and specific markings sets it apart from any other local bugs we’ve commonly seen around here. Anything you can offer in the way of identification will be appreciated. Incidentally, I came upon your website trying to find out what the numerous insects are that we see flying around each Spring that look like giant mosquitoes. Your site shows Crane Flies that have a similar look, but we can’t be certain. Thanks for your help.
Frank Atzert
Bedford, TX

Hi Frank,
Thanks to your excellent photo with scale, no one should ever have a problem identifying a Cottonwood Borer, Plectodera scalator.

Letter 6 – Cottonwood Borer

elm beetle?
Hi.. wondered if you wanted these pics…they are some type of elm beetle( sorry , in too big ahurry to look them up) found in Maud,Ok,74854 yesterday , May 28 2006 Thanks for your fabulous site..and have a safe Memorial Day…..
Debbi
I got some time to look on your site ..heres what you have under the first beetle page: “8/13/2003) The COTTONWOOD BORER, Plectrodera scalator, is a large black and white beetle that is most likely your culprit. It is a member of the long horned borer family. The grubs bore into the trees and can cause considerable damage.” Hi …got wondering if those first pics I sent were too big , so here they are resized…though , as dangerous looking as they are , a full size pic is much more impressive,lol…Debbi in Maud,OK

Hi Debbi,
We see you already identified your Cottonwood Borer before we had a chance to respond. We spent the whole day gardening, stopping just long enough to bar-be-que.

Letter 7 – Cottonwood Borer

Please identify!
Hello, Bugman ~ please tell me what the heck this is!!!
Thanks!
Backyard Bunny

Hi Bunny,
This is a Cottonwood Borer, one of our most striking native Cerambycids.

Letter 8 – Cottonwood Borer

Fort Riley Bug
Location: Fort Riley, Kansas
July 11, 2011 8:08 pm
My girlfriend found this bug perched outside her house on the rail and we were wondering what kind of bug it was. Grasshopper face and beetle on the back end. Is it dangerous? Thanks in advance
Signature: Angelic Lutz

Dear Angelic,
It is highly unlikely that the distinctive Cottonwood Borer will be confused with any other insect.  It is not dangerous, though it has strong mandibles and it might bite if carelessly handled.

Letter 9 – Cottonwood Borer

Beautiful very large bug
Location: Central Nebraska – plains
July 30, 2011 3:33 pm
Here’s a photo of this giant bug that landed on my window screen here in central Nebraska yesterday morning. Though I’ve scoured the site trying to find one similar the only pic that came close was the Longicorn from Thailand and we’re a little far from there. lol
This guy is about 2” long, as big around as a woman’s pinky finger and has these amazing long antenna and legs! He has wings obviously since he flew onto the window screen but can climb and stick to anything he chooses.
Thanks for your help identifying him AND if you could please answer one question – what does he eat? I’d greatly appreciate knowing that answer.
thanks so much for you excellent information.
Signature: Marguerite

Hi Marguerite,
This is a Cottonwood Borer, Plectrodera scalator, one of the Longhorned Borer Beetles in the family Cerambycidae.  Longhorned Borers are also called Longicorns, generally in French speaking countries, and Thailand was occupied by the French.  It was astute of you to recognize the family resemblance.  According to BugGuide:  “Adults are reported to browse on shoots of host trees, especially leaf-stems (petioles), and bark.”  Try feeding this Cottonwood Borer young leaves from a cottonwood tree.  Most of our reports come from Texas and Oklahoma, and you may be our first report from neighboring Nebraska.

Letter 10 – Cottonwood Borer

Subject: What’s this bug?
Location: Oklahoma City
July 15, 2012 10:28 am
Was found flying around a warehouse in Oklahoma City.
Signature: Librafamily

Dear Librafamily,
This very distinctive beetle is a Cottonwood Borer.

Letter 11 – Cottonwood Borer

Subject: what bug is this
Location: Southwestern, KS, US
July 11, 2013 6:46 am
Plz help
Signature: Julie

Hi Julie,
This large and distinctive beetle is a Cottonwood Borer, Plectrodera scalator.  Almost all of our Cottonwood Borer images come from Texas and Oklahoma.  It is nice to have a submission from nearby Kansas.

Letter 12 – Cottonwood Borer

Subject: Cottonwood Beetle
Location: West Alton, Missouri
August 5, 2014 7:35 pm
I know this is a Cottonwood Beetle, found at the Riverways Migratory Bird Sanctuary in West Alton, Missouri on August 5, 2014. I’ve never seen one of these before and they are impressive looking.
Signature: Cara Mengwasser

Dear Cara,
Your image is positively gorgeous.  We generally crop images so that the “bug” is featured nicely for the web, and the same is true of your image, but we are also posting your entire image so that our readers can appreciate the loveliness of this Cottonwood Borer within the landscape, and we hope folks know that clicking on the images on our site in postings after 2009 will bring up an enlarged view in a new screen.  While Cottonwood Borers are not the largest Longicorns in North America, and we can think of a few that are prettier than the Cottonwood Borer, it is probably the prettiest, really large Longicorn, and we fully agree with you that it is an impressive site.

Letter 13 – Cottonwood Borer

Subject: Beetle juice
Location: Broken Arrow, Oklahoma
August 14, 2014 1:45 pm
Hi Man of Bugs,
I am from Oklahoma and it is super hot out here right now. I found this guy coolin’ down in the climate control units at Aspen Mini Storage. I believe it’s a Cottonwood Borer but I thought he was a beaut and had to show you!
Thank you!
Signature: Sommer

Hi Sommer,
You are correct that this is a Cottonwood Borer, and it is an impressive and unforgettable beetle.

Letter 14 – Cottonwood Borer

Subject: I found a bug and I have no idea what it is
Location: Van Buren Arkansas
July 26, 2015 4:39 pm
I found a white bug with kind of black spots I guess that’s what you would call them. he has one bike on either side of his neck and black long antennas.
Signature: if you could get back to me that would be great thank you

This distinctive beetle, which really resembles no other North American species, is a Cottonwood Borer, Plectrodera scalator.  According to BugGuide, it is in a “monotypic genus” meaning it has no close relatives with which it is classified.

Letter 15 – Cottonwood Borer

Subject: Black & Yellow Bug
Location: Tarrant County Texas
June 13, 2016 4:12 pm
Any idea what this bug is.
Signature: RBG

Dear RBG,
Though your image is not properly focused, we are thrilled to post the first Cottonwood Borer sighting of the year reported to our site.  We generally get several submissions of Cottonwood Borers from Texas and Oklahoma each June.

Letter 16 – Cottonwood Borer

Subject: Weird bug
Location: Florida
June 8, 2016 8:52 pm
What kind??
Signature: Curious bug hater

Dear Curious bug hater,
Almost all of our reports of Cottonwood Borers are from Texas and Oklahoma, so your Florida sighting is unusual, though BugGuide reports the species from both Florida and California and as far north as Michigan.

Letter 17 – Cottonwood Borer

Subject: What kind of bug is this?!
Location: North Texas
July 8, 2016 2:23 pm
Dear Bugman,
My son and I stumbled across this sucker while at a house viewing. It is fairly large, perhaps an inch and a half to two inches long with very large antennae. It is a pale yellow and black and was very active. Thanks for any help given, my kid was pretty excited about it.
Brian
Signature: Brian

Dear Brian,
This beautiful beetle is a Cottonwood Borer, Plectrodera scalator.  According to the Great Plains Nature Center:  “The bold coloration of the cottonwood borer is due not to colors in the exoskeleton, but rather to masses of small white hairs, which are only visible with magnification.”

Daniel,
Thanks so much for the quick response! Have a great weekend.

Letter 18 – Cottonwood Borer

Subject: Camping
Location: Texas, usa
May 30, 2017 9:14 am
This bug flew at my wife on our vacation. Scared crap out out of her. Lol what is it.
Signature: Kevin williams

Dear Kevin,
This distinctively marked beetle is a Cottonwood Borer.  They are not dangerous to humans, but like many wood boring beetles, they have strong mandibles and they might even draw blood from a thin-skinned person. 

Letter 19 – Cottonwood Borer

Subject:  Identify bug
Geographic location of the bug:  North Richland Hills, Tx
Date: 06/27/2019
Time: 08:57 PM EDT
Your letter to the bugman:  Can you identify this bug that was on my back porch?
How you want your letter signed:  David

Dear David,
This distinctive beetle is a Cottonwood Borer.  Most of our reports come from Texas and Oklahoma.

Letter 20 – Cottonwood Borer

Subject:  What kind of an insect is this?
Geographic location of the bug:  Houston, TX
Date: 07/09/2019
Time: 01:50 PM EDT
Your letter to the bugman:  I saw this 6 legged insect on our loading van. I’ve never seen it before and wanted to know what it was. I’m very interested in finding out more. Thank you!
How you want your letter signed:  Your Bug Identified

This gorgeous beetle is a Cottonwood Borer.  According to Texas A&M The Field Guide to Common Texas Insects:  “Adults are commonly encountered on trunks and branches of cottonwood and willow trees and other host plants during the summer months. Infested mature trees are usually not seriously injured. Larval stages are rarely encountered unless heavily infested young trees are killed or fall over; medically harmless.”