The broad necked root borers can be horrible tree pests. In this article, I will share some tips on how to get rid of broad necked root borer and keep their infestation at bay.
The broad-necked root borer (Prionus Laticollis) is a tree pest most common to deciduous trees.
These reddish brown or black colored insects are often mistaken to be the Asian longhorn beetle, but there are significant differences between them.
Broad Necked root borer, true to its name, causes damage to the roots of trees and can destroy the root system.
One of the few ways to get rid of these pests is through contact insecticides that contain pyrethroids.
I will talk about these in detail in the article below.
Are Broad-Necked Root Borers Dangerous?
The male broad-necked root borers have sharp mandibles, while the female ones are bigger, but their mandibles are not.
While these pests appear as though they could sting badly, they usually do not engage with humans. Neither do they bite or sting, nor are they poisonous.
The males use their mandibles only when fighting for territory with fellow males.
Female broad necked root borers have a very visible ovipositor at the end of the abdomen.
The ovipositor resembles a stinger and may look deadly, but in reality, it is the egg-laying structure in female insects that are not used for biting or stinging.
During the breeding season, the female will use the ovipositor to lay her eggs in the ground.
Hence even though root borers look like they could harm you, these notorious little pests are not dangerous to humans or animals.
But the same cannot be said for plants; they are gravely dangerous to their roots. Both young and very old trees are at risk from their infestation.
What Damage Do Broad Necked Root Borers Cause?
As their name suggests, broad-necked root borers are tree pests that affect and damage the roots of trees.
They usually attack weakened shrubs and plants. Hence it’s important to maintain your plant’s health using good fertilizers and regular trimming.
If your plant is young, a root borer infestation could kill it.
When it comes to older trees, an infestation at the roots could cause them to fall or get blown over.
Unfortunately, there aren’t any major indicators for a root borer infestation.
One telltale sign is the yellowing and thinning of foliage. You might also notice small holes or cracks in the bark and trunk of the tree or plant.
If you suspect a root borer infestation in a tree, the only way to confirm is by uprooting the tree itself.
If there is a severe infestation, the tree might be held to the ground by one or two roots only, so uprooting it would be very easy.
Differences Between Broad Necked Root Borers and ALBs?
The broad-necked root borers are often mistaken for Asian longhorn beetles (ALB). However, there are significant differences between the two.
Let’s start with the physical differences.
The Asian longhorn beetle has a narrow body with white spots, while the broad-necked root borer is more full-bodied and has no spots.
The root borer has much shorter antennae than the ALB and a visible ovipositor in females.
As far as their life cycle is concerned, the broad-necked root borers pupate within the soil and move towards and feed on trees once they transition into adults.
However, the female beetle lays eggs and lets it larvae pupate in a tree’s heartwood directly.
Both these insects are tree pests, but the ALB attacks the canopy of a tree while the root borers damage the root system of trees.
Lastly, unlike the ALB, the root borer also attacks fruit trees and shrubs.
In addition to deciduous, maple, and willow trees, root borers can also infest hickory, dogwood, pecan, and oak trees.
How To Get Rid of Broad Necked Root Borer?
It’s far easier and better to prevent a broad-necked root borer infestation than treat it.
But regardless, there are some ways you can treat it. Insecticides are the best way to get rid of broad-necked root borers.
Start with spraying a contact insecticide with pyrethroids on the outer surfaces of the tree, such as on the trunk, branches, and bark, to destroy live insect activity.
Pyrethroid insecticides with Cypermethrin are considered the best. Cypermethrin is an active ingredient that is useful in preventing a root borer infestation.
The earlier you treat the infestation, the better because this contact insecticide will prevent the newly hatched tree borer larvae from proceeding toward the trunk.
If you see borer holes in the trunk or loosened parts on the bark, inject aerosol insecticides directly into it.
This method will take care of insect activity behind the bark and attack beetle larvae and adult beetles.
If the infestation is more robust, dig holes around your tree in the soil and pour an insecticide mixture into it for the roots to absorb it.
Once the root system absorbs the insecticide, it’ll get dispersed upwards, preventing root borers from digging further.
It’s also a good idea to add some liquid fertilizer along with your insecticide mixture when applying it to roots.
The fertilizer will give your trees an additional strength boost and help keep them healthy further, just in case the root borer infestation is not very severe.
Natural Ways of Removing Broad Necked Root Borers
There are very few options when it comes to the natural control of these bugs.
Some insects, including Jepson’s beetle or Plaesius javanus, have been known to predate them in the food chain.
Ants and some birds can also eat them. However, the problem is that since they reside in the roots, they are very hard to see.
Preventing Broad-Necked Root Borers
As I said earlier, preventing an infestation is better than treating it. Here are a few ways to protect your trees from root borer infestation.
- Pruning and trimming your plants and trees is the top way to keep a root borer infestation away.
- Regularly cutting decaying leaves and branches will make your plants and trees uninviting to the root borers.
- Don’t forget to apply and seal the cuts and wounds from pruning with a prune paste.
- This will facilitate the healing process of the trees while also preventing the root borers from penetrating the trunk.
- One part of keeping your trees healthy also involves keeping the surroundings clean.
- Regularly clear out grass and fallen leaves from the base of the trees. Also, avoid littering near the trees.
- Less litter would mean fewer places for these tiny pests to hide. It will also make them easily visible to you or any other predator.
- Surround your trees and plants with mulch, organic fertilizers, and supplemental water to prevent the root borers from causing further damage.
- If you find significant damage to your tree/plant from the infestation, uproot it and replace it with a new one.
- Ensure you carry out the contact insecticides treatment for the new plantation to prevent a re-infestation.
Frequently Asked Questions
How do you control root borers?
By taking preventive measures and using treatments, root borers can be managed efficiently.
For prevention, you should plant seedlings of the proper size and strength and manage soil fertility properly.
Narrow-spectrum Insecticides specifically designed for root borers can help remove them from your garden.
Techniques such as mulching around plants also help to stop the pests from approaching plant roots.
Plants such as buckwheat or other flowering species can help attract adult root borers and keep them away from your crop trees.
How do you get rid of tree borers naturally?
Tree borers are a menace to your outdoor trees, but you can take action to prevent infestations and get rid of existing ones naturally.
Pruning and regularly inspecting trees for small holes and sawdust-like frass is one way to spot early signs of an infestation.
You can also use organic solutions such as natural oils and insecticide soap sprays to kill the larvae located inside the tree.
Additionally, applying sticky barrier wraps around the trunk can catch adults before they have a chance to lay eggs.
Taking these steps, along with providing proper nutrition, watering, and tending, will help ensure that your outdoor trees remain healthy and free from tree borers naturally.
What is the best remedy against borers?
The best remedy against borers is to use an Integrated Pest Management (IPM) program.
IPM is based on preventative measures such as good cultural practices, mechanical controls, and biological control.
This includes using resistant varieties, removing weeds, keeping plantings healthy, and using compost and mulch.
Biological controls can be helpful in managing borers by releasing beneficial insects that attack insect pests that may harm plants.
Mechanical traps or barriers can also be used to trap or exclude borers from the garden.
If needed, carefully chosen chemical treatments should always be a last resort and applied only where necessary according to label directions.
Is Neem oil good for borers?
Neem oil is effective in controlling borers because borer larvae are highly susceptible to the compounds found in Neem oil.
When applied to foliage, neem oil acts as a barrier so that borers cannot feed on the leaves and instead ingest the oil.
It also inhibits the growth of eggs and larvae by preventing them from processing food properly, as well as by interfering with calcium metabolism.
This makes it an ideal treatment for killing borers and deterring their return.
Additionally, neem oil is biodegradable and does not persist in the environment for long periods of time after application.
Wrap Up
The broad-necked root borers are tree pests that can damage a variety of trees by attacking their root systems.
The best way to deal with an infestation of these little buddies is to ideally prevent it.
You can do this by using contact insecticides and regularly maintaining your trees/ plants through pruning and using healthy organic fertilizers.
Thank you for reading!
Reader Emails
Due to the fact that broad necked root borers reside in the ground, they are rarely seen by our readers.
However, this also means that anyone who spots them is curious to know what they are and how to get rid of them.
Over the years, we have collected an assortment of several such letters, along with many photographs of these bugs.
Please go through them below.
Letter 1 – Female Broad Necked Root Borer
Found this guy on the rock wall in our yard. He was approx. 3 inches long (didn’t want to get too close w/ the tape measure). Everytime someone came close to him a long stinger would come out the back and a clear liquid would run along it to the tip. With the stinger he was approx 4 inches long. Is this bug poisonous? If there is one is there usually more? I appreciate any info. Thanks.
Denise
Hi Denise,
This looks to be a female Broad Necked Root Borer, Prionus laticollis. BugGuide has a photo that indicates scale. The stinger you mention is actually her ovipositor. Eggs are laid deep underground. According to BugGuide: “Eggs are inserted into ground (or under litter) in groups. Larvae tunnel downward to feed on living roots of a variety of trees and shrubs. At first they may feed on bark, but then proceed to hollow out small roots. Pupation occurs in spring, about 10 cm under the ground. Life cycle probably three years.” They are not poisonous. They are found in the Eastern U.S. and there are no recent reports from Florida, perhaps due to global warming. We wish you had included a location in your letter.
Letter 2 – Female Broad Necked Root Borer
July 7, 2010
We found this bug on the side of a maple tree. It is about two inches long not measuring what looks like a stinger that it can retract. It doesn’t move much and looks impressive. We looked all through the beetle pictures and couldn’t find a match. Can you help us?
Thanks!
Walnut Hill Gang
Natick MA
Dear Walnut Hill Gang,
Your beetle is a female Broad Necked Root Borer, Prionus laticollis. The stinger is actually the ovipositor of the female and she uses her ovipositor to deposit eggs. According to BugGuide: “Eggs are inserted into ground (or under litter) in groups. Larvae tunnel downward to feed on living roots of a variety of trees and shrubs. At first they may feed on bark, but then proceed to hollow out small roots. Pupation occurs in spring, about 10 cm under the ground. Life cycle probably three years.“
Letter 3 – Female Broad Necked Root Borer
July 8, 2010
Saw this large Black and orange tailed beetle in my garden in upstate NY, near the capital. One of the biggest bugs I am seen around this area. Can you help identify it?
Sincerely Ryan
Upstate NY
Hi Ryan,
This is a female Broad Necked Root Borer, Prionus laticollis, a species that we have posted several images of in the past few days. The orange tail that you describe is her ovipositor and she uses it to bury her eggs where the hatchling larvae have access to roots, their food source.
Letter 4 – Female Broad Necked Root Borer
Location: Albany, NY
June 19, 2011 8:45 pm
Hi Bugman,
My kids and I found this beetle wandering in our lawn near a flower bed at the side of the house. any ideas what it is?
Signature: Bill in Albany, NY
Hi Bill,
This large beetle is a female Broad Necked Root Borer, Prionus laticollis, a species found in the Eastern half of North America. Females are reported to be flightless, and the trimmer males have longer antennae and they are attracted to lights.
Letter 5 – Female Broad-Necked Root Borer
Location: Long Island, New York, USA
June 28, 2011 5:48 pm
I don’t think I’ve seen a bug this big in New York before. It’s slowly walking around my sidewalk and sticking its butt up in the air like this, with a yellow thing that is protruding and retracting.
Signature: J
Hi J,
Your insect is a female Broad-Necked Root Borer, Prionus laticollis, and the yellow thing is her ovipositor which is used to lay eggs. According to BugGuide: “Eggs are inserted into ground (or under litter) in groups. Larvae tunnel downward to feed on living roots of a variety of trees and shrubs. At first they may feed on bark, but then proceed to hollow out small roots.”
Letter 6 – Female Broad-Necked Root Borer
Location: West Milford, NJ
July 1, 2011 11:45 pm
Looks like a Broad-Necked Root Borer to me. Kudos to your site! I looked at three other sites and maybe 50 pages of beetle pics to no avail. This site made it easy or I guessed really good on the second beetle choice I made. So here’s a photo of top and bottom. About 2 inches long and scary. It was doing its ovipositor thing into the soil of my garden when I found it and figured out what it was up to. Made the wife fetch the camera for me so I could ID it later. This was third such critter I spotted and the first time since we moved here 3.5 years ago.
Signature: -Stan [Farmer Gray Beard]
Hi Stan,
We are happy to hear our website was helpful. We have gotten significantly more reports this year of Root Borers, so we believe we made a good decision when we chose the Broad-Necked Root Borer as the Bug of the Month for July 2011.
Letter 7 – Female Broad-Necked Root Borer
Location: Brentwood, NY 11717 (40.782418,-73.251817)
July 3, 2011 1:32 am
What the hell is this thing??? found it in my apartment. lost in my dirty clothing pile…
Signature: Henry Z. Wilkie
Hi Henry,
This is a female Broad Necked Root Borer, our feature Bug of the Month for July 2011. According to BugGuide: “Female much larger than male. The former is reported to be flightless, or nearly so. Males are attracted to lights.” We wonder how this flightless or nearly flightless female found her way into your dirty laundry, though this specimen is not as robust as most of the females represented in photographs we have received.
Letter 8 – Female Broad Necked Root Borer
Location: southern jersey shore (miles south of Atlantic City)
July 8, 2011 10:23 pm
I found this little one in my office/garage, crawling around, with a very unamused wife. With everyone wanting me to squish it, I figure if i name it, and make it a pet, they cant kill it… But I would like to know what it is first.
She is all black, with 6 legs, a hard shell with lines straight down its back, the shell doesnt seem to be connected to the lower part of the body, and head and middle section are articulated. She wouldnt stand straight to get and exact length, but my dial caliper says she is about 2” long.
thanks,
sloopy.
Signature: sloopy
Hi Sloopy,
This is our featured Bug of the Month for July 2011, the Broad Necked Root Borer, Prionus laticollis. You may read more about her on BugGuide as well. According to BugGuide, adults eat foliage of fruit trees and grape vines, so try feeding her fresh leaves daily.
Letter 9 – OVIPOSITOR: Female Broad Necked Root Borer
In an attempt to better educate our readership, we have created a new tag that will better explain some important Buggy Vocabulary Words, beginning with Ovipositor
Here is what the online Webster has to relay: “a specialized organ (as of an insect) for depositing eggs”. Future Buggy Vocabulary Words postings will include Phoresy, Metamorphosis and the ever popular Exuvia.
Location: Monmouth County, NJ
June 13, 2012 6:37 pm
I found this beetle on a juniper shrub in my garden. Not used to seeing such large arthropods in this area. Wondering if it is dining on my shrubs and control measures if that is the case.
Thanks
Signature: JK
Ed. Note: This conversation was rescued from the trash. We will use this to create a new tag for Buggy Vocabulary Words
female root borer, not generally plentiful enough to be a problem.
Dear JK,
This is a female Broad Necked Root Borer, Prionus laticollis (See BugGuide), and what appears to be a stinger is her ovipositor, an organ adapted to facilitate in the egg laying process. Generally, the longer the ovipositor, the further the female must bury her eggs. A Stump Stabber, a totally unrelated member of the wasp family might have the longest ovipositor in the insect world, and some female Stump Stabbers in the genus Megarhyssa have ovipositors as long as five inches. It is believed that in stinging insects like wasps and bees, the ovipositor has evolved into a stinger that the female may use if she is threatened. It has caused to wildly speculate about the dual purpose of the ovipositor in wasps, and we can’t help but to wonder if a wasp deposits an egg each time she stings and if her venom might somehow serve some other purpose that benefits the egg. Wouldn’t it be the craziest thing if when a female Tarantula Hawk stings and paralyzes her prey, she might deposit an egg during the stinging process? That is most likely a crazy thought, but it gives us a reason to link to the Tarantula Hawk as an insect whose sting caused by a modified ovipositor is reported to be among the most painful in the insect world. We even put the Tarantula Hawk in the coveted first position when we created The Big 5 tag last summer and promptly forgot to inform the webmaster we had a new tag.
Letter 10 – Female Broad Necked Root Borer with Ovipositor extended.
Location: Andover, NJ, backyard
July 8, 2012 4:18 pm
Sorry to be emailing twice in one day, but my husband just showed me this monster bug and I have NO idea what it is! It was in our yard, sitting on some race-car tires. I was able to get within six inches of it to take pictures. It is a little over an inch long without the rear-protrusion. When I was able to get it to move, it dropped to the ground, rustled around in the grass and seemed to go underground. Hoping you can ID this for me!
Signature: Deborah Bifulco
Hi Deborah,
This is a female Broad Necked Root Borer, Prionus laticollis, and she has her ovipositor extended. Though it resembles a stinger, the ovipositor is an egg laying organ that has been modified into a stinger in insects like bees and wasps. In the case of the Broad Necked Root Borer, the ovipositor will not cause any harm to humans. According to BugGuide: “Eggs are inserted into ground (or under litter) in groups. Larvae tunnel downward to feed on living roots of a variety of trees and shrubs. At first they may feed on bark, but then proceed to hollow out small roots. Pupation occurs in spring, about 10 cm under the ground. Life cycle probably three years.” The Broad Necked Root Borer is in the Longhorned Borer Beetle family Cerambycidae, and we get the lion’s share of our North American reports and identification requests from this family from June through August, especially the Prionid subfamily to which the Broad Necked Root Borer belongs.
By the way, this is a stunning photograph. We can’t help but to wonder if she is releasing pheromones into the air. We are quite confident with the guess that she is.
Thanks so much for the ID, Daniel, as well as the ID on the other two bugs I spotted yesterday. My husband saw this big girl again yesterday later in the afternoon, on the same stack of tires and with her ovipositor extended. What an amazing looking bug!
Debbi
Gene St. Denis confirms pheromone suspicions.
Daniel …, they release female pheromones this way , for mate attraction . Cheers ! Gene St. Denis Sierra Nevada Research
Letter 11 – Female Broad-Necked Root Borer
Subject: Broad neck root borer?
Location: Binghamton NY
July 16, 2014 7:50 pm
Heres the pics, crazy looking beetle in NY. Didnt expect this find
Signature: Mr NY
Dear Mr. NY,
Your multiple angle views of a female Broad-Necked Root Borer are an excellent addition to our archives. The belly shot shows the lighter coloration and the head-on view reveals the powerful mandibles that should be avoided when handling large and powerful Prionid Beetles.
Letter 12 – Female Broad-Necked Root Borer
Location: Connecticut
June 27, 2016 5:17 pm
Hi…my cousin found this bug on her mother’s driveway and wants to know what it is, hope you can help. Thank you
Signature: Sarah
Dear Sarah,
This is a female Broad-Necked Root Borer and her ovipositor is showing.
Letter 13 – Female Broad-Necked Root Borer Ovipositing
Location: northeastern CT
July 7, 2016 3:19 pm
My son found this beetle or roach on an oak tree while we were walking through the UCONN campus in Storrs, CT. It has large jaws clamped onto the bark, a striped under belly and black top along with a light amber colored “tail”. From jaws to tip of tail is close to 3 inches. Could you help us identify it?
Signature: Homeschool Mom of 3
Dear Homeschool Mom of 3,
This is a female Broad-Necked Root Borer in the process of laying eggs. The “tail” is her ovipositor, an organ used to lay eggs.
Letter 14 – Female Broad-Necked Root Borer
Location: Western North Carolina, elevation 3500 ft.
July 5, 2017 3:08 pm
Came across this guy in the western North Carolina mountains July.
Signature: LB
Dear LB,
This is a female Broad-Necked Root Borer, and we looks like a stinger is actually an ovipositor, an organ used to lay eggs. Here is a BugGuide image for verification.
Letter 15 – Female Broad-Necked Root Borer
Location: Swansea. MA 02777
July 8, 2017 3:47 pm
This guy turned up 3 days ago, didn’t see him yesterday as it rained. He has been in the position on the brick for a number of hours. He has changed direction and as it gets later is no longer noise down. The pictures with the blue background were from 3 days ago. The brick ones are today July 8, 2017 in Swansea, MA we have walked past him numerous times but he has not moved.
Signature: wendleskins
Dear Wendleskins,
This is a female Broad-Necked Root Borer, and what appears to be a stinger is actually an ovipositor that she uses to lay eggs.
Letter 16 – Female Broad-Necked Root Borer
Location: Bedford MA
July 9, 2017 2:52 pm
So, this is from my woodsy backyard in Bedford, MA. I saw her with her ovipositor all the way out. She was on a brick in the back yard. You can probably see from the pics she is at this weird angle with her held tilted down and the back end of her body higher in the air, like 45 degrees. The weird thing about the ovipositor, if this is a broadnecked root borer, what is she doing with it out here? No tree around – I think you told someone else maybe putting out some pheromones? But in the photo you can see there is this light yellowish/green thing midway on the ovipositor, extending up and kind of wiggling around there. Almost looked like a tiny inch worm the way it was moving. What the heck is that thing?
Signature: Minnie
Dear Minnie,
Your identification of a female Broad-Necked Root Borer is correct, but alas, we cannot with any surety respond to your questions. It seems female Broad-Necked Root Borers are frequently sighted with extended ovipositors though they are not actually in the act of laying eggs. We are not certain how the female’s egg-laying apparatus actually functions. Perhaps one of our readers will be able to supply some answers.
Letter 17 – Female Broad-Necked Root Borer
Location: MA
July 20, 2017 9:13 pm
I was walking by dog in the backyard and we have woods, pond, and bogs right in our backyard. I saw this walking on the ground. What is it??
Signature: Jen
Dear Jen,
This is a female Broad-Necked Root Borer, a common summer sighting in the eastern portion of North America. It appears that she might be laying eggs.
Letter 18 – Female Broadnecked Root Borer
Location: Florida
August 7, 2017 6:25 pm
Found this at work today, inside a building. What is it and will it sting ?
Signature: Sally
Dear Sally,
This female Broadnecked Root Borer does not sting. What you have mistaken for a stinger is actually an ovipositor used to lay eggs.
Letter 19 – Female Broad-Necked Root Borer drowns in pool
Geographic location of the bug: Piedmont, North Carolina
Date: 06/21/2018
Time: 03:43 PM EDT
Your letter to the bugman: (Forwarding this for a friend who couldn’t get the photos to send)
This was found in a pool skimmer and unfortunately didn’t spring back to life when rescued.
How you want your letter signed: Kitsa
Dear Kitsa,
This is a female Broad-Necked Root Borer and what appears to be a stinger is actually her ovipositor, an organ used in laying eggs.
Letter 20 – Female Broadnecked Root Borer
Geographic location of the bug: Richmond, VA
Date: 06/25/2018
Time: 01:56 PM EDT
Your letter to the bugman: Hi, I found this insect in its last throws of life on its back in my garage. I only got underside photos, as I was not about to flip it over. I did manage to lift it and get it back to mother nature, but I didn’t want to get close once it was back on its feet. Thanks.
How you want your letter signed: Martin
Dear Martin,
This is a female Broadnecked Root Borer, Prionus laticollis, a species that is active in the Eastern portion of North America during the months of June and July.
Letter 21 – Female Broad-Necked Root Borer
Geographic location of the bug: Monroe, NY
Date: 07/01/2018
Time: 07:03 PM EDT
Your letter to the bugman: I’ve never seen this before. What is going on?
How you want your letter signed: Sciteacher
Dear Sciteacher,
This is a female Broad-Necked Root Borer, Prionus laticollis, and her ovipositor is extended. The ovipositor is an organ the female of many species of insects uses to lay eggs, but we are confident she is not attempting to lay eggs on the plank upon which the image was taken. According to BugGuide: “Eggs are inserted into ground (or under litter) in groups. Larvae tunnel downward to feed on living roots of a variety of trees and shrubs. At first they may feed on bark, but then proceed to hollow out small roots. Pupation occurs in spring, about 10 cm under the ground. Life cycle probably three years.”
Letter 22 – Female Broad-Necked Root Borer
Geographic location of the bug: Long Island, NY
Date: 07/02/2018
Time: 08:19 AM EDT
Your letter to the bugman: Hi – my friend found this beetle in her backyard and I’m wondering what kind of beetle it is.
How you want your letter signed: Thanks so much, Linda
Dear Linda,
This is a female Broad-Necked Root Borer with her ovipositor extended. Root Borers mature and are active during summer months in many parts of the country, and we have been receiving numerous requests for their identification.
Letter 23 – Bug of the Month July 2019: Female Broad-Necked Root Borer
Geographic location of the bug: bel air md
Date: 06/30/2019
Time: 01:49 PM EDT
Your letter to the bugman: what is this beetle and what is coming out of its butt?
How you want your letter signed: Peg
Dear Peg,
In July 2011, we designated the female Broad-Necked Root Borer, Prionus laticollis, as the Bug of the Month, and we believe enough time has elapsed to select your submission as our Bug of the Month for July 2019. The ovipositor, an organ used for laying eggs, is protruding from the end of her abdomen. According to iNaturalist: “The female is larger than the male, with an ovipositor used to deposit eggs. When the female is laying eggs, she “shivers” and eggs are laid through the ovipositor, positioned down into the soil or under litter, usually in groups of threes and twos, but sometimes ones or fours. After the eggs are laid, the female moves her ovipositor up and down to fill the hole she created. When freshly laid, the eggs are pure white, glistening with moisture, but, after a while, they usually change to a deep yellow. Within a few days, the deep yellow eggs turn to a light washed pink. As the larvae develop inside, the eggs turn ivory in color. The eggs are the size of small grains of rice. When the larvae are hatching, they chew through one of the elongated, pointed sides of the egg. The larvae’s heads are adapted for digging into the soil, and they have strong black mandibles for chewing roots.”
wow… how cool! thanks for your response!
Peg
Letter 24 – Broad Necked Root Borer
Hi there…
I know the summer is really busy, but I was at a friend’s farm, and we found this bug on a tree in her yard. If you touch the white thing protruding from its abdomen, it pulls it all the way back in. It didn’t seem aggressive, but then she found another one and when she put them in a jar together, they fought. Can you please tell me what kind of bug this is?
Thank you,
Jonel M. Nightingale
Hi Jonel,
This is a female Broad Necked Root Borer, Prionus laticollis. The ovipositor protruding from the abdomen is used to lay eggs beneath the bark and the immature grubs feed on the wood.
Letter 25 – Broad Necked Root Borer
We found this beetle while walking the dog in his “yard”. From what I can tell it is a carrion beetle of some type – but larger than I have ever seen. It appears to be a ?gravid? female that occasionally extends a half-inch long ovipositor. I tried to get the ruler in the photo, but it was moving around – she is over 2 inches (5 cm) long and nearly 2.5 inches long if you measure to the tip of the antennae. Largest beetle I have ever seen – What is it exactly?? Thanks,
C. Tumminello
Waynesboro, PA
Hi C,
This is a Broad Necked Root Borer, Prionus laticollis.
Letter 26 – Broad-Necked Root Borer
Tue, Jul 7, 2009 at 11:35 AM
Hi there,
I was wondering if you could tell me what this bug is? I don’t think that I have ever seen one quite like this before. Plus I thought that my husband took an excellent picture of it and wanted to share with you. This creature is about 1 1/2 to 2 inches long without the appendage that is sticking out.
Katie Thibeault
Hooksett, NH
Hi Katie,
This is a female Broad-Necked Root Borer, Prionus laticollis. The appendage is her ovipositor and she uses it to deposit eggs in the ground.
Letter 27 – Broad Necked Root Borer
June 25, 2010
I was having a conversation with my girlfriend outside on the porch when we were interupted with a loud scratching noise that eventually made its way all the way around us. At first we though it was my cat but then realized it was something moving through the brush. Upon closer inspection we realized it was some sort of huge insect. Well, I discovered this, she on the other hand was completely disgusted….lol I captured it in a Priority Mail box and seriously considered mailing it to my annoying PIA boss….but decided otherwise and now im emailing you after googling “Huge insect Virginia” and discovering this site. At first we though it was a roach but I have never seen one this large in VA and the large pinchers are not something that I have ever seen on a roach.
Paul D
Richmond, VA
Dear Paul,
Your letter is so amusing we wanted to take a bit of additional time to respond to it, so we slept on it. Sunrise is still a ways off, but we are awake and ready to give your letter the attention it deserves. At first we thought that this was a female Tile Horned Prionus, Prionus imbricornis, one of the Root Borers. The sexes can be distinguished by the sexually dimorphic antennae. According to BugGuide: “Antennae have 18-20 overlapping segments (male): Female has 16-18 serrated segments. Other eastern Prionus have 12-13 antennal segments.” Upon magnifying your photos and counting the antennae, we could only make out 13, but the images are not critically sharp for that degree of scrutiny.
We now believe this to be a female Prionus laticollis, the Broad Necked Root Borer, which BugGuide describes as: “Pronotum as broad, or almost as broad, as base of elytra. Very dark. Elytra have irregular punctures, and each elytron has three indistinct longitudinal ridges. Pronotum has three blunt lateral teeth on each side. Antennae have 12-13 segments. Female much larger than male. The former is reported to be flightless, or nearly so. Males are attracted to lights.” We love your photos and your amusing letter. We hope your boss doesn’t catch wind of your fantasy and retaliate against you. Seriously though, the inadvertent shipping of stowaway insects in packages is sometimes responsible for species range expansion though more often than not invasive exotic species are spread on plants when they are shipped to remote locations. In the event that we decide to do a 2011 calendar, we would love to include your letter and images because they are both so amusing.
July 17, 2010
Sorry for the long reply. That is funny, and yes it would be great if you wanted to use my story for the calander.
Paul
Letter 28 – Mating Broad Necked Root Borers
Location: New Hampshire
July 9, 2011 6:21 pm
This was digging a hole in my back yard, is it dangerous?
Signature: Randall
Dear Randall,
We are most excited to post your photo of mating Broad Necked Root Borers, Prionus laticollis, our featured Bug of the Month for July 2011. The larval grubs feed on the roots of trees, but they are not considered a pest species and it is doubtful there would be such a high population on a single tree that they would negatively impact the health of the tree. Root Borers have very strong mandibles, and though they are not an aggressive species, should they be carelessly handled, they might deliver a painful bite and possibly even draw blood.
Letter 29 – Drowned Broad Necked Root Borer
Location: Western Pennsylvania
July 25, 2011 1:32 pm
I found this poor drownd beetle floatig in my swimming pool yesterday and I really want to know what it is because I have never seen anything like it before. It is huge, as you can see compared to the size of the fly. I have tried searching the internet, but couldnt find very much. Please note that I did not kill this bug. I was, in fact, trying to save its little life but it was dead when I found it.
Sorry 
Signature: LadyStardust
Dear LadyStardust,
We cannot get the picture out of our minds of you attempting CPR on this unfortunate male Broad Necked Root Borer, our Bug of the Month for July. The antennae of the male are much more developed than those of the female. The backyard swimming pool is one of the most deadly traps for insects and other arthropods, and you need not fear this posting getting tagged as Unnecessary Carnage. We understand that it was accidental drowning. It appears as though the Fly might be a Blow Fly in the genus Lucilia, which included the Green Bottle Fly (see BugGuide). Blow Flies are Stage One Colonizers of decomposing corpses in the increasingly popular field of forensic entomology thanks to all of the CSI style television shows (though Crossing Jordan may have set the stage for the field with “Bug” Ravi Kapoor) and high profile murder trials like that of Casey Anthony.
Letter 30 – Broad Necked Root Borer drowns in pool
Location: Lindenhurst NY
July 2, 2012 4:34 am
I’m wondering who this poor soul is that I found in my skimmer. He looks like the things nightmares are made of. Any help is apreciated.
Signature: Billy T
Hi Billy,
This is one of the Root Borers in the genus Prionus and we believe it is a male (based on the size of the antennae) Broad Necked Root Borer, Prionus laticollis. You can compare your image to this photo on BugGuide. At this time of year we get numerous reports of Root Borers from around the country.
Letter 31 – Broadnecked Root Borer
Subject: Name that beetle
Location: South Western Pennsylvania
July 8, 2013 5:52 pm
We found this beetle in south western Pennsylvania around 8:00pm on our back porch. It is fairly large maybe the size of a half dollar coin. We are curious as we have never seen this type of beetle before.
Signature: Joe
Dear Joe,
This impressive beetle is a male Broadnecked Root Borer, Prionus laticollis. They are attracted to lights, so that might be the reason you found it on your back porch. The antennae of the males are much more developed than those of the female.
Letter 32 – Broad-Necked Root Borer lays Eggs in Captivity
Location: Akron, Ohio
July 2, 2015 10:10 pm
I found this 2 inch long bug yesterday crawling through the grass. We at first thought it might be Hardwood Stump Borer, but now I’m thinking it’s a Broad-Necked Root Borer. All my info coming from bug books and the internet.
Today it started laying eggs in the bottom on the jar. The kids were fascinated! I have hardwood trees as well as apple trees and grape vines. I don’t want to release it if it is going to be damaging to my trees, but I don’t want it to suffer either. If I can find what kind of beetle it is, then I can feed it or release it elsewhere. I also, could let it go once it’s done laying eggs, (unless it mates and lays eggs multiple times).
Here is a picture of the top of the beetle, the bottom, and some with the eggs (they look kind of like rice).
Signature: Sharon
Dear Sharon,
This is a Broad-Necked Root Borer. According to BugGuide: “Eggs are inserted into ground (or under litter) in groups. Larvae tunnel downward to feed on living roots of a variety of trees and shrubs. At first they may feed on bark, but then proceed to hollow out small roots. Pupation occurs in spring, about 10 cm under the ground. Life cycle probably three years.” There is no indication that the feeding habits of the larvae compromise the life of a healthy tree as they feed on the small roots only. Many gardeners feel that trimming roots helps to stimulate new growth. We would advise you to release this magnificent beetle. Thank you for supplying an image with the eggs. Some female insects emerge from pupation so filled with eggs that they release some unfertilized eggs to enable them to fly better.
Letter 33 – Two Prionids: Brown Prionid and Broadnecked Root Borer
Location: Southern New Jersey
July 18, 2016 7:28 am
Dear Bugman, I recently had the pleasure of encountering several what I believe to be are beetles in our recently purchased home? At first I thought one was surely was a cockroach but after doing some research I believe it is a beetle. These beetles are huge, never seen before in my life here in New Jersey. Root Borer? Prionus? The 1st picture is what I surely thought was a cockroach and was found inside our home and we moved it outside. 2nd was found after dark walking along outside by our patio door. 3rd was one found outside our home in the early morning apparently dead. Thanks so much for your help!
Signature: Sincerely, Chuck
Dear Chuck,
Your first image, the beetle you mistook for a Cockroach is a Brown Prionid, Orthosoma brunneum. The second is a female Broadnecked Root Borer, Prionus laticollis. Both are classified in the subfamily Prioninae, but they are in different genera. Your third beetle is a male Reddish-Brown Stag Beetle. We receive numerous identification requests for each of these three species every summer.
Daniel, cannot thank you enough for taking the time for identifying them. Sorry they were so common, I’ve never seen a beetle that large in all my life, let alone few different species of something that large. Our home backs to the woods with lots of older some dead trees. Thanks again for your time and help!
Chuck
Hi again Chuck,
There is no need to apologize. It is nice being able to post new images of different species each year.
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