Are Longhorn Beetles Dangerous? Some of Them Are

Longhorn beetles are denizens of trees and spend their entire lives boring tunnels through them, making them hollow. But are longhorn beetles dangerous? In this article, we will talk about them in more detail.

Have you observed pencil-like holes in the bark of several trees near your home?

Or you might have noticed that the leaves of backyard trees suddenly start yellowing despite the season being spring.

These are the signs that longhorn beetles have infested the tree. These beetles can destroy trees by tunneling inside them and making them nearly hollow.

In this article, we will discuss longhorn beetles and how dangerous they are.

What Are They?

There are many species of longhorn beetles scattered across the world. The beetles can vary in size. An average longhorn beetle can grow from 0.25 to 3 inches long.

They have dark brown or black bodies with white spots on them.

When adult beetles lay eggs, they do it in freshly cut trees. Their larvae emerge from eggs and burrow into the tree bark for food. They create tunnels in the wood and live there for more than 2-3 years

The longhorn beetle larvae are white to yellowish in color and have a worm-like shape.

Longhorn beetles are known to perform a pivotal role in the decomposition and nutrient-cycling process in forest regions.

These beetles are known to consume living organisms and dead organisms; in some cases, they even consume dying organisms.

Are These Bugs Dangerous to Humans?

These beetles usually do not enter human houses, but they can sometimes come in from freshly cut pieces of wood brought indoors.

These beetles pose no threat to humans as they rarely show any aggressive behavior towards humans.

You will be relieved to know that they also cannot attack the furniture or damage the household properties. However, they will crawl around the house, creating a nuisance.

Are They Poisonous?

These beetles don’t have a venomous sting and are not poisonous to human beings. The only real threat is that they can damage trees.

Moreover, longhorn beetles are rarely seen attacking humans or pets. However, they will attack if you try to manhandle them, and their bites can cause severe pain.

Do Longhorn Beetles Bite?

These beetles are known to eat both living and dead organisms. They attack both old and healthy trees to eat wood.

Adult Asian Long-horned beetles (Anoplophora glabripennis) are herbivorous and usually feast on leaves, twigs, and other plant matter.

They are known to cause damage worth billions of dollars due to their penchant for eating through trees like poplar trees, elm trees, and so on.

They rarely sting or bite humans or pets, but they will bite if you mishandle them. The bite can cause a blister on your skin. Therefore one must be careful around them.

What Damage Can They Do?

Asian Longhorn Beetles, one of the insects from this family of beetles, can cause massive damage to trees.

In some cases, they are responsible for completely destroying big healthy trees.

These beetles are especially attracted to mountain ash trees, maple trees, willow trees, and more.

The larvae of the beetles grow inside these trees and spend one to three-years tunneling through them, eating the wood.

This makes the tree hollow, and even a strong gust of wind can knock an entire beetle-infested tree.

Symptoms of an Infestation?

If an Asian longhorn beetle has occupied a tree near your house, you might see some of these creatures loitering around your yard or house.

However, these beetles are usually hard to track and get rid of. Here are a few common signs that will help you detect a longhorn beetle infestation:

• You might notice some chewed-up round depressions in the bark of the tree.
• Pencil-sized round exit holes in the tree are another indication.
• There might be a high amount of sawdust gathered around the base of the tree.
• Non-seasonal yellowing and shedding of leaves.

Frequently Asked Questions

Wrap Up

The longhorn beetles are ecologically significant creatures.

Despite their ability to completely destroy healthy trees, it is claimed that their presence ensures a healthy nutrient cycle throughout a forest.

Dealing with these insects can be difficult, but we hope after reading this article, you will be able to identify them and take measures to stop their damage.

Thank you for reading the piece. 

Reader Emails

Several readers have shared with us pics of longhorned beetles to identify these rather funny-looking creatures over the years.

Please sample the wid variety of longhorned beetles from our reader’s archives below.

Letter 1 – Puerto Rican Long Horned Beetle: two foreign mystery bugs

 

What an excellent and fun website! I thought you might be able to help me with two mystery bugs that have proven baffling. The second is this strange bug my entomology class in Puerto Rico. We were stuck, and I still am – I can’t place it to order even, although the mouthparts and thorax might suggest some weird orthopteran. This specimen was about 2 and a half cm from antennae-tip to the base of wings.
Thanks!
Robbie

Hi Robbie,
Thanks for the photos of the exotica. They are a mystery to us as well. Your Puerto Rican Orthopteran looks according to Eric Eaton, to be probably a longhorned beetle (Cerambycidae).
Ed. Note: We just received the following correction.
(08/09/2005) identifications Hello – I was recently shown your site, and it is excellent. My specialization is longhorned beetles, and in cruising around I notice a number of incomplete or uncertain IDs for this family. I don’t know if you are interested in receiving this sort of input, but if you are, I offer the following additions to your identifications.
This is a species of Bebelis, probably lignosa, or perhaps schwarzi; no species is specifically recorded from Puerto Rico, but several my occur there. The larvae typically bore in small stems of semi-woody plants (sunflower, ragweed, etc.) Cheers.
Frank Hovore

Letter 2 – Aristobia approximator: Longhorn Borer Beetle from Malasia

 

Could not identify this bug anywhere on the internet.
Hi, I’m Jason Lai from Malaysia and I need some of your help to identify this bug. I caught it in Fraiser’s Hill, Malaysia for an insect collection project and its due next thurs (25/1/2007). hope you can identify the bug by then. thx!
Jason

Hi Jason,
This is Aristobia approximator, one of the Longhorned Borer Beetles in the family Cerambycidae. We found this identification in a wonderful book we were given entitled Living Jewels by Poul Beckmann printed by Prestel. We then did some web searching with the name and discovered this beetle has appeared on stamps from Laos in 1974, North Vietnam in 1977 and Central Africa in 1962. It can also be found for sale to insect collectors on many sites.

Letter 3 – Longhorn Borer Beetle from India

 

colourful bug in india
hi bug man,
told you i had more, mostly cos i don’t know the first thing about identifying bugs.
anyway in found this little guy in india in my room in Trivandrum. night time not very active didn’t move even after a substantial amount of shooting. was the only one of its kind i have ever seen and i do look. February 2008.
[email protected]
Trivandrum, India

Hi [email protected]
This is a Longhorn Borer Beetle in the family Cerambycidae. Sorry we can’t be more specific than the family.

Hi [email protected]. Most longhorn beetles (Cerambycidae) are fairly drab so I thought yours would be relatively easy to track down – not so. I suspect that your beetle is either uncommon or hasn’t made itself and agricultural or forestry pest. I took several approaches and all trails seemed to lead to the genus Batocera (sufamily Lamiinae). This genus includes several notorious pests, perhaps most notably the mango stem-borer (Batocera rufomaculata), which is a serious problem in India and many other parts of south Asia. The genus also includes a number of species with brilliant red markings. I was able to find one internet site that featured a Batocera sp. that looks very similar to yours at: http://albumo.com/photo/212955/Longhorn-Beetle—Batocera-sp..html. The photos are from Malaysia, but many Asian species are quite widespread. I suspect this may be a closely related species. Cheers. K

Correction courtesy of Karl:  December 4, 2016
Hi Daniel and rastaPoPoy:
It looks like this longicorn and the one from your archives are indeed the same species. Although I previously suggested that it might be a species of Batocera, it seems I was on the wrong track. In checking again I am now going to suggest that this lovely beetle is Olenecamptus bilobus (Cerambycidae: Lamiinae: Dorcaschematini). The species is widely distributed throughout Asia and Melanesia, and comes in a variety of colour variations. Two  subspecies occur in India; O. bilobus bilobus and O. bilobus indianus. The two subspecies are quite similar and your two postings could belong to either one. Here are some additional images from Assam and the Seychelles.  Regards  Karl

Letter 4 – Banded Hickory Borer from Oklahoma

 

another unknown longhorn not on wtb!
Sun, Mar 8, 2009 at 7:18 PM
Hi,
I found this little guy in our pool on Friday, and have found several others since then. I haven’t seen these before, and I have no idea what kind of longhorn they are. I searched through all your longhorn pages and couldn’t find them. They are about 1 ½ inches long, and are light grey with two light brown marks on their wings. They were found in central Oklahoma. I appreciate any help you can provide.
Josh Kouri

Hi Josh,
We want to format all three of your photos for posting and we don’t recognize your Longhorn Borer Beetle. We hope Eric Eaton or another reader can supply an answer that may take us considerable time to research, so we are posting it as unidentified.

As with many male Longhorn Borer Beetles or Longicorns, your specimen displays some mighty impressive antennae. The photo of your beetle about to take flight nicely illustrates how the hardened elytra are positioned when the soft flying wings are needed.

 

Update: Hi, Daniel:
The lovely longhorned beetle is a male “banded hickory borer,” Knulliana cincta.  We actually have a subspecies of that beetle emerging in Arizona right now!  I didn’t know they came out this early.  I got some in Missouri when I lived there, but seem to recall it was later in the year….They are not a destructive species.
Eric

Letter 5 – Long Jawed Longhorn Beetle

 

Orange and Black Bug
Tue, Jul 7, 2009 at 10:13 AM
We were enjoying a 4th of July BBQ in Cave Creek, AZ when this guy decided to join us. Right after I snapped the picture on my iPhone (attached) he flew away. His body was about an inch long. Can you help me figure out what kind of bug this is?
Desert Knight’s Ranch
Cave Creek, AZ

This really is an attractive Cerambycid or Longhorned Borer Beetle.  We searched on BugGuide until we properly identified it as a Long Jawed Longhorn Beetle, Trachyderes mandibularis.  It is found from Texas to California and south to Guatemala.  Also, according to BugGuide, “Males have particularly long mandibles” which would indicate that perhaps your beetle is a female.  It seems that females of the Long Jawed Longhorn Beetle have antennae nearly as long as those of the males.

Letter 6 – Longhorn Beetle from China: Batocera rubus

 

Chinese beetle
November 10, 2009
Hello,
I saw these on a (low) hill path in Zhongshan in China yesterday and wondered what they are? Is it mother and child or a male/female couple? Thanks
Neil
Zhongshan city, GuangDong, CHina

Hi Neil,
The markings on your beetles are different than those on examples of Mango Stem Borers, Batocera rufomaculata, that we have posted previously, but there are enough similarities for us to question if this is perhaps a regional variation.  Your beetles might be a closely related species in the genus Batocera, like perhaps Batocera davidis, or perhaps a member of another genus in the Long Horned Borer family Cerambycidae.  In our opinion, this is a couple.  Perhaps one of our readers can assist in this identification.

Update from Karl
Hi Daniel:
They are definitely a Batocera species (Cerambycidae: Lamiinae: Batocerini) but not B. rufomaculata. There are several similar looking species in Asia, but as far as I can tell only B. davidis and B. rubus occur in China. The B. davidis photo that you linked to does look very much like the ones in Neil’s photo, but most images of B. davidis do not show the prominent white spots on the elytra. This could be an example of regional variation, or it could be another case of misidentified photos on the web. On the other hand, there are numerous postings of B. rubus and they all appear very similar. For comparison, the ‘Siam Insect-Zoo & Museum’ site has excellent photos and descriptions of all the species mentioned here. I think I have to go with B. rubus. Coincidentally, I also came across a photo of mating B. rubus (subspecies mniszechi) from the Philippines that is remarkably similar to the one posted by Neil. Regards.
Karl

Letter 7 – Golden-Bloomed Grey Longhorn Beetle from UK

 

LONGHORN BEETLE ??
June 6, 2010
LONGHORN BEETLE ??
I cannot find a picture exactly like this after a long search – is this british?
Possibly more than an inch long, on cow parsley, active = hard to focus camera, extremely pretty – what is it and should it really be here?
Sue Climpson
RG28 7SX, Whitchurch Hampshire UK

Hi Sue,
First we need to say that we understand your frustration at not being able to find this Golden-Bloomed Grey Longhorn Beetle, Agapanthia villosoviridescens, in your online searching.  We began our search by typing the family and location, Cerambycidae and UK, and we were immediately led to the ideal website for the search, bioimages.org.uk, but alas, we could not figure out how to access the images of the insects that were recorded in UK.  By all indications, this should be an easy task, but we kept encountering obstacles.  Undaunted, be began to copy and paste the names indicated on the website in a new browser window and searching with the information provided.  Finally, we landed on the Golden-Bloomed Grey Longhorn Beetle page of Bioimages and though we still do not know how to access the images on that site, the name led us to a wealth of other sites with matching images of your beetle, beginning with Wikimedia Commons.  The NatureSpot website indicates:  “Mainly found in moist meadows and hedgerows.  Adults feed on umbellifers such as Hogweed and Cow Parsley as well as on Nettles” and “A stem borer that breeds in the stems of thistles and other herbaceous plants.”  Though we were quite frustrated with the very user unfriendly BioImages website, we are thankful for the list it provided for our search.

Letter 8 – Longhorned Borer Beetle: Graphisurus fasciatus

 

Female Longhorn Beetle
July 14, 2010
Hi Daniel,
This lady made her way into my living room last night. I put her up for the night so I could get some photos. I think I have mached her to an image on Bug Guide http://bugguide.net/node/view/126701 if this correct it is a Cerambycidae Beetle – Graphisurus fasciatus. Never saw a common name (which I prefer) The number of insects living around me is amazing and I never took the time to look before now. Thank You and have a wonderful day.
Richard
North Middle Tennessee

Hi Richard,
We believe you have correctly identified this Longhorned Borer Beetle without a common name, Graphisurus fasciatus, based on images posted to BugGuide.  We also love the graphic look of your photograph.

Letter 9 – Black Longhorned Borer Beetle from Colorado

 

Beetle on my dead tree
Location: Aurora, Colorado
June 6, 2011 1:49 pm
I have a tree that just recently died and it’s got bore holes all over it which is why I assume it died. I’ve attached two photos of some beetles I found on the tree. I can’t tell if they’re what are boring the holes or if they’re just hanging out as I havent been able to find any tennants in the holes.
Signature: Mike

Dear Mike,
This is a member of the Longhorned Borer Beetle family Cerambycidae, known as the Bycids for short.  The larvae bore in the wood of trees and shrubs and most species are very host specific.  While some species do considerable damage to living, healthy trees, many members of the family will only infest trees that are already compromised by disease or stress.  What species of tree is this?  The bark resembles a Eucalyptus, but we want to know for certain.  We don’t recognize the beetle, but those enlarged hind femora are a good identifying feature.  We haven’t the time to identify this species at the moment, but you can try browsing through the possibilities on BugGuide.  We already spent about ten minutes searching with no luck.  We will also try to contact Eric Eaton to see if he recognizes this species.

Eric Eaton Responds
Daniel:
Something in the genus Callidium.  Should be several species in Colorado.  Here’s more:
http://bugguide.net/node/view/42797/bgpage
Have fun in Colorado!
Eric

Thanks Eric,
This image on BugGuide is nearly identical.

Letter 10 – Longhorned Borer Beetle from Domican Republic

 

What kind of beetle
Location: Cabrera, Dominican Republic
October 6, 2011 2:19 pm
We were visited by this beetle during our recent trip to Cabrera, Dominican Republic. He/she spent a few days up there watching the festivities. He/she was a bit over 3” long. The locals said they call it a crunchy beetle because of the noise it makes when the step on em.
Signature: OregonJac

Dear OregonJac,
This is a Longhorned Borer Beetle in the family Cerambycidae.  We would further classify it as a Root Borer in the subfamily Prioninae.  We found a video on YouTube of the largest beetle in the Dominican Republic called Xixuthrus domingoensis, but its mandibles are smaller.  Perhaps you have the male of the species and the larger female has smaller mandibles though we are not convinced they are the same species.

Ed. NOte:  We found this in our draft box and we are not certain why it was never posted nearly two years ago.

Letter 11 – Flower Longhorn Beetle: Strophiona laeta

 

Subject: Longhorned borer
Location: Silverton, OR
August 21, 2012 4:33 am
This one has been bugging me (no pun intended)
I know it’s a longhorn beetle and by the size of the antennae and colors I would say it looks like a Neoclytus caprea or a Typocerus velutinus but the pattern and coloration are quite different. I live in Oregon and caught him by blacklight. Hopefully you can give me a positive id.
Signature: Jesse

Hi Jesse,
Your photos are beautiful.  Do you have a straight dorsal view?
We will research this and get back to you.

Thanks, this is a little personal project i’ve been doing.  This snapshot is as close to the view as i have. I turn on a couple backlights by my house every night and see what lands on my window. I live adjacent to an white oak grove if that helps narrow it down at all. I have never scene this type before so i was kind of excited.
-Jesse

Hi again Jesse,
Thanks for sending the dorsal view.  This is a gorgeous Longhorned Borer Beetle and we don’t believe it will be too difficult to identify, but it might take some time.  We just returned from a long day at work and we are preparing the posting and tagging it as unidentified while we do the research.  We hope to have an answer for you shortly.

Hi again Jesse,
We believe we have correctly identified your gorgeous Longhorned Borer Beetle as Stenostrophia tribalteata.  There are several subspecies profiled on BugGuide and the species ranges from California to western Canada.

WTB? contacts Doug Yanega
Hi Doug,
I believe I have correctly identified this beauty as Stenostrophia tribalteata.  The specimen was attracted to a black light in Silverton, northern Oregon at the edge of a white oak grove.  Now I am beginning to doubt the ID I made because no photos show the yellow underbelly and the pubescence that appears on the ventral surface as well as the thoracic region.  Can you confirm or correct and possibly narrow to subspecies?   Also, any thoughts on black lights to attract Cerambycids?
Thanks for any possible information.
Daniel

Ed. Note:  Another possiblity
Moments after reaching out to entomologist Doug Yanega, we believe we might have identified the correct species as Strophiona tigrina, which appears to be a much better match according to images posted to BugGuide.  The data for the range on bugGuide is also a match.  Again, there is no specific information on BugGuide and the banding pattern is not exactly the same as the individual on the Natural History of Orange County website.  Strophiona laeta, which BugGuide reports from California might be the best match.

Doug Yanega confirms Strophiona laeta.
That’s correct.

Letter 12 – Longhorned Borer Beetle from Dominican Republic is Callipogon sericeum

 

Subject: Is this a CALLIPOGON ?
Location: Jarabacoa, Dominican Republic.
November 11, 2012 8:36 am
This giant bug, about 4” long was found this morning in Jarabacoa. Dominican Republic.
Can you please help me identify it?
Signature: Mario Davalos

Dear Mario,
We know we have seen images of this beetle or a close relative previously, however, we are having problems identifying it, so we decided to post your image prior to an identification.  We do not believe it is in the genus Callipogon, though we do believe it is in the same subfamily, Prioninae.  We checked several websites with no luck, including Coleop-Terra and the Worldwide Cerambycoidea Photo Gallery where the closest match we could find are the members of the genus Macrodontia. We did not think a beetle this distinctive would be so difficult to identify.  We are going to contact Eric Eaton for assistance.

Thank you.  I’ll await news. Hopefully we’ll be able to identify it.
Regards
Mario

Hi again Mario,
It seems you were correct with the Callipogon identification.  Our loyal reader and frequent contributor Cesar Crash from Brazil has provided the name Callipogon sericeum as the species and the Harvard Collection of Caribbean Insects has fourteen images of mounted specimens from the collection.  We also found a matching photo on the Cerambycidae of Cuba website despite our original search of those key words coming up blank.  Perhaps not all males have such well developed mandibles, or perhaps some of the images posted online are actually of different species.  At any rate, all indications are that this species is a rarity that is commanding very high prices on online auctions of individuals nowhere near as impressive as the individual in your photograph.  Congratulations on a gorgeous photograph of a living specimen, especially since we cannot seem to find any other examples of living males with such developed mandibles anywhere online.

Letter 13 – Female Longhorn Borer Beetle

 

Subject: what is this
Location: tinton falls,nj
June 10, 2015 6:58 am
I think this bug flew inside, found in my monmouth county, tinton falls nj next to the woods apartment.
Moves quickly walking, possibly flies
As its still its long and narrow
Not sure if that’s a stinger?
Please help!!
Signature: -P

Dear P,
This is a Longhorned Borer Beetle in the family Cerambycidae, and what you have mistaken for a stinger is the ovipositor, and organ that is used by the female when laying eggs.  We did a web search using the key words “Cerambycidae, ovipositor, New Jersey” and we were led to Green Art and an image of Graphisurus fasciatus and the information that it:  “is well camouflaged when moving about on tree bark. The best way to find it is near lights in the night. The larvae are boring into hardwood. Note the large ovipositor of the females.”  We verified the identification on BugGuide.

Letter 14 – Antlike Longhorn Beetle from New Zealand

 

Subject: Ant’s
Location: Central North Island, New Zealand
October 26, 2015 8:20 pm
I found this in my garden today, its is about 4mm in body length and dark blue with these two yellow spots
Signature: Mike

Dear Mike,
Though it resembles an Ant, this is actually a Longhorn Beetle in the family Cerambycidae.  Several years ago we posted an image of a mating pair that were identified as being in the genus Zorion.  there are many nice images on the GrahamNZ website and there is also a nice image on FlickR. 

Thank you for the information.  I phoned someone who should have known and was told by him it was a flower bug
At least I know its basically harmless.  It will now go in the files with the spiney spiders found last year
Mike

Hi again Mike,
In defense of your source, we do have a comment on our previous posting indicating this is a Flower Longhorn, however our research, including a scholarly article on the Massey University of New Zealand site, has determined that it is in the subfamily Cerambycinae, not Lepturinae whose members are commonly called Flower Longhorns according to BugGuide.

 

Letter 15 – Longhorned Borer Beetle from Arizona is Megacyllene antennata

 

Subject: What is this fascinating critter?
Location: Gold Canyon, AZ
February 25, 2016 5:46 pm
Wandered into our camp in Gold Canyon, AZ. Anyone know what this is?
Signature: Deirdre

Dear Deirdre,
This is a Longhorned Borer Beetle in the family Cerambycidae, and we need additional time to determine its identity.  We have written to Eric Eaton for assistance.

Eric Eaton Responds
Daniel:
Yes, it is Megacyllene antennata.  Here’s a link:
http://bugguide.net/node/view/29440
Thanks for sharing!
Eric

Ed. Note:
According to BugGuide, the food plants for the southwestern species are:  “mesquite and (catclaw?)”

Letter 16 – Long-Jawed Longhorn Beetle

 

Subject: Orange striped beetle?
Location: Tombstone AZ
August 9, 2017 1:23 pm
What is this bug?
Signature: Terri

Dear Terri,
This gorgeous Longicorn, Trachyderes mandibularis, is commonly called a Long-Jawed Longhorn Beetle.  According to Texas Entomology:  “There are 16 species of Trachyderes (in two subgenera), but only T. m. mandibularis reaches the United States.”

Letter 17 – Ant-Mimic Longhorn Borer Beetle

 

Subject:  Beautiful beetle
Geographic location of the bug:  Central Ohio
Date: 05/07/2019
Time: 07:09 PM EDT
Your letter to the bugman:  Found this gorgeous beetle on my arm.  May 7th 2019.  In a lightly wooded area with nearby stream. At first I thought it was an ant, but the antenna look like a beetle.  The texture of the abdomen is like a blister beetle.
How you want your letter signed:  Jennifer Huffman

Dear Jennifer,
We were impressed with how much this Longhorned Borer Beetle in the family Cerambycidae resembled an Ant, so we researched that and located this image of Cyrtophorus verrucosus on BugGuide.  According to BugGuide:  “Ant mimic. Distinctive markings, and note also knobs at base of pronotum” and “Adults take nectar and/or pollen on spring-flowering trees and shrubs.  Larvae feed on a wide variety of hardwoods, including Acer, Betula, Carya, Castanea, Cercis, Cornus, Fagus, Quercus, Ulmus, & Pinus.“

Wow super cool!   I won’t tell you how many long horned beetles I looked at late last night trying in vain to find something like this.  Too bad I couldn’t get better pictures, maybe I should have chilled him too!
Thanks so much for the fascinating info and for saving my sanity.
Jennifer

Hi Jennifer,
BugGuide does indicate:  “A remarkable ant mimic, this species runs like an ant.”