Why Do Stink Bugs Stink? Unraveling the Mystery

Stink bugs, as their name implies, are known for the unpleasant odor they emit. You might wonder what causes these creatures to smell so bad and how this feature benefits them in the wild. In this article, we’ll explore the reasons behind the stink of these bugs and how this unique characteristic helps them survive.

A stink bug’s signature odor is produced by a chemical compound they excrete from glands in their bodies. These glands are located on the underside of their thorax, and when the bugs feel threatened, they release the foul-smelling liquid as a form of defense. The strong and unpleasant scent serves as a deterrent to predators, ensuring a better chance of survival for the stink bug.

Various stink bug species exist, and they can be found in many different environments, from agricultural fields to suburban neighborhoods. Some examples include the green stink bug (Acrosternum hilare) and the brown marmorated stink bug (Halyomorpha halys) [link to the search results]. Although the specific odors may differ slightly, all stink bugs share this pungent reputation and rely on their distinct smell to keep them safe from harm.

What Makes Stink Bugs Stink

Chemical Components of the Odor

Stink bugs produce a mix of odors due to the chemical cocktail present in their glands. These chemicals include:

• Aldehydes: Responsible for the strong, pungent smell.
• Esters: Contribute to the fruity or sweet component of the odor.

These components work together to create the distinctive smell stink bugs are known for.

Glands Responsible for the Smell

Stink bugs have special glands located in their thorax that contain the chemical cocktail responsible for the odor. When they feel threatened, the bugs can release these chemicals onto a rough part of their exoskeleton called the evapatorium.

Here’s a simple comparison of stink bug glands and their function:

By understanding the chemical components and the glands responsible for the smell of stink bugs, you can better comprehend why these insects emit such a strong odor as a defense mechanism.

How Stink Bugs Use Their Odor

Defensive Mechanism

Stink bugs are notorious for the foul smell they produce as a form of self-defense. When feeling threatened, they release a potent odor from their thorax to ward off predators, which can be quite unpleasant for both pests and humans alike (source).

For example, if a person or animal were to disturb a stink bug, it might release the smelly chemicals from its special glands in response (source). This can discourage predators from attacking the bug and protect it from harm.

Attracting Mates

Stink bugs also use their odors as part of their mating process. These chemical cues are called pheromones and help stink bugs locate and attract potential partners. Pheromones are not the same as the defensive odors; they are generally not detectable by humans or other non-target species.

In summary, stink bugs utilize their ability to produce odors for both:

• Defense against predators
• Attraction of mates

Using these tactics, stink bugs can effectively protect themselves and ensure the survival of their species.

Common Stink Bug Species and Their Habitats

Brown Marmorated Stink Bug

The Brown Marmorated Stink Bug (Halyomorpha halys) is an invasive pest native to Asia. It was introduced to the United States in the mid-1990s, possibly by hitching a ride in a shipping container. This species feeds on a wide range of plants, damaging crops and becoming a concern for farmers.

It’s important to understand that the Brown Marmorated Stink Bug can be found in countries like China, Japan, Taiwan, Korea, and has also spread to Canada. Their habitat includes agricultural fields, gardens, and various wooded areas.

Red-Shouldered Stink Bug

The Red-Shouldered Stink Bug is another common species prevalent mainly in the United States. Although they are similar in appearance to the Brown Stink Bug, they exhibit red or orange markings on their shoulders which makes them distinct.

These bugs also have a tendency to feed on plants, but their impact on agriculture is not as significant as the Brown Marmorated Stink Bug. Their preferred habitat includes trees, shrubs, and fields where they can easily find their food sources.

Spined Soldier Bug

The Spined Soldier Bug is unique in that it’s a predatory stink bug. Unlike other stink bugs that feed on plants, this species primarily preys on other insects, especially caterpillars and beetle larvae.

Due to their predatory nature, they can be beneficial for controlling other pests and can potentially be advantageous to agriculture. Spined Soldier Bugs can be found across the United States and are more adaptable to various environments than other stink bug species.

In conclusion, while stink bugs can be a nuisance and have a negative impact on agriculture, it’s essential to understand their differences, behaviors, and habitats to effectively manage and control their populations.

Stink Bugs in the Home and Garden

Attracting Factors for Stink Bugs

Stink bugs are attracted to homes and gardens for various reasons. In your garden, they are drawn to a variety of plants, including fruits, vegetables, and crops. Examples of plants they feed on are:

• Fruit trees: apples, peaches, and pears
• Garden vegetables: squash, corn, beans, tomatoes, peppers, and eggplants

In addition to food sources, stink bugs are attracted to warmth and moisture. As temperatures drop in fall and winter, they search for warm places to overwinter. This is when they invade your home by entering through cracks on walls or foundations, or around windows.

Stink Bugs and Home Invasions

Homeowners have to deal with stink bugs invading their homes, especially during fall and spring. Once inside, they find shelter in warm and secluded areas. To prevent them from entering, you can:

• Seal cracks on walls and foundations
• Install weather stripping around windows

If they are already inside, you can use a vacuum cleaner to remove them from your walls and ceilings. Be sure to dispose of the vacuum bag to avoid the lingering smell they produce when crushed.

Stink Bugs and Agricultural Damage

Stink bugs pose a significant threat to agricultural production. As an agricultural pest, they cause damage to tree fruits, garden vegetables, and crops like sweet corn and soybeans. They use their straw-like mouthparts to pierce and suck the nutrients from fruits and plants, resulting in distorted growth or even crop loss.

Here’s a comparison of their impact on your home versus agricultural environments:

By being aware of stink bugs and their habits, you can prevent them from causing damage to your home and garden. Take preventive measures and act promptly when you notice their presence to protect your plants, fruits, and personal spaces.

Preventing and Controlling Stink Bugs

Creating a Stink Bug-Proof Home

To prevent stink bugs from entering your home, focus on sealing gaps and openings. Apply caulk or silicone around windows, doorways, and cracks in the walls. Additionally, install door sweeps to keep these pests from sneaking under doors.

In Pennsylvania and other heavily infested regions, using window and door screens is another effective way to exclude stink bugs from entering your home. Repair or replace any damaged screens to maintain a secure barrier.

Natural Stink Bug Repellants

There are several natural options available to help you get rid of stink bugs. One such option is diatomaceous earth, a natural powder that damages the bugs’ exoskeletons and causes dehydration, ultimately killing them. Spread the powder around areas where you suspect stink bugs may crawl or gather.

Essential oils can also help deter stink bugs. Some examples include:

• Lavender oil
• Peppermint oil
• Eucalyptus oil

Mix a few drops of these oils with water and spray around entry points, window sills, and other areas where stink bugs may enter.

Professional Pest Control and When to Call

If natural methods and preventive measures are not sufficient, you may need to call a professional exterminator for assistance. Pest control experts can use targeted and effective measures such as traps, light traps, and pesticides to eradicate stink bug infestations.

When to call a professional depends on the severity of your stink bug problem. If you frequently encounter multiple stink bugs inside your home, or if natural methods have not worked, it may be time to seek professional help.

Remember that even when employing professional pest control services, it is still essential to maintain preventive measures like sealing gaps, caulking, and using screens to minimize future stink bug invasions.

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 – Stink Bug Eggs on Parsley

Subject: Eggs on underside of parsley leaf
Location: Gary, IN
April 12, 2016 9:06 am
Hello, Bugman:
Have you any idea what insect would put these eggs on this parsley leaf? Thank you.
Mary Ann Sumner
Signature: Mary Ann

Dear Mary Ann,
Our money is on these being Stink Bug Eggs, but we cannot say for certain which species.  Here is a relatively similar looking clutch of eggs from BugGuide.

Thank you, Daniel.  I was cutting parsley leaves to add to a salad dressing and luckily spotted them before I whizzed them in the blender.  I guess I could say I almost ate them :-}    . . .  and it probably wouldn’t have been a first.
I posted the pic on Facebook and it created quite a stir.
Thanks, again.
Mary Ann

Letter 2 – Stink Bug and Nasty Reader #1 Comment

‘carafe shape’ answered in nasty reader section
August 23, 2010 10:37 pm
dearest bugpeeps: OMG! I was drawn to read your highly entertaining and mindboggling NRAs, and what did i find? my beetle, at nasty reader award no 1 !! Thank you for a most informative and entertaining online research session. you guys are the (bug) bomb!
Signature: terre zenk

Dear terre,
We are happy you successfully identified your Hawthorne Shield Bug and were entertained in the process.

carafe-shaped mark
Location:  west seattle
August 23, 2010 10:12 pm
I found this little beetle on my shirt the other day. I’ve not been able to find it by shape or color, and there are SO MANY beetles. I live in Seattle. thanks in advance for your help–your site is amazing!
terre zenk

Hi terre,
We are trying to piece together the various components of your submissions into one posting.  Interestingly, we also responded to you with a short generic Stink Bug reply to your photo submission.  The Nasty Reader was from the UK, and we believe your Stink Bug is Banasa dimiata which according to BugGuide is:  “Reported from the entire United States, southern Canada and northern Mexico.”

Letter 3 – Spotted Shield Bug from Costa Rica

Subject: Cool Costa Rican Beetle
Location: Santa Elena, Costa Rica
February 25, 2015 7:59 am
We found this beetle at high elevations in Costa Rica (Santa Elena/Monteverde in February) I’ve looked around and can’t seem to find a picture to identify it. Can you help? It was found on a fence between cleared farmland and forest near an ant trail.
Signature: C Avilez

Dear C Avilez,
This is not a Beetle.  We quickly identified this Shield Bug in the family Scutelleridae as a Spotted Shield Bug, Pachycoris torridus, thanks an image on FlickR.  Some of the variations in markings and coloration are pictured on Neotropical Entomology.

Letter 4 – Stink Bug

A new species for you — I think
This guy came by to hang out at my computer this evening (St Paul, MN), and was kind enough to pose for some pictures. I think this is Banasa dimiata, a Stink Bug in the family Pentatomidae. Yes, I know my wall is fuzzy 🙂 Thanks for a great site! Best wishes–
henry

Hi Henry,
Thanks for the new Stink Bug species. We are splitting your letter apart as it makes it easier for us to post only one species per letter.

Letter 5 – Stink Bug

Unknown Green & yellow bug
Hi, my name is Kathleen and I live in the southern part of New Jersey. I hope you can help me identify this little creature my spouse found in our apartment last night. My spouse and I spotted it on my oil lamp trying to climb up the strand that the ‘rain drops’ come down on. (It was having trouble because of the oil that was on there,though the lamp was off at the time.) We were able to get him out and put him in a water bottle with a small amount of water to rinse the oil off of it. (We also put many air holes in the bottle.) I searched the pics on your site and think it may be a true bug or stink bug…but I am not an expert and none were green with yellow spots like mine. Please give me any info you can on the creature and what we should do with it. I have attatched some pics (hope they help).
Thank you so much;
Kathleen & Bob
PS Your site is great! (So much info!)

Hi Kathleen and Bob,
This is a Stink Bug. We believe it to be in the genus, Chlorochroa, probably Chlorochroa sayi, Say’s Stink Bug.

Update From Eric Eaton:
” The green stink bug is actually Banasa euchlora, substantially smaller than a Chlorochroa. I can see how the markings are confusing, though”

Letter 6 – Stink Bug

What is this ?
Hi,
Noticed this guy crawling outside my window. Could you tell me what it is? I live in Nova Scotia Canada.

Hi John and Tracey,
Your Stink Bug,Menecles insertus, photos are perhaps the most intriguingly beautiful ones we have seen. They are truly works of art.

Letter 7 – Stink Bug

What is this?
We are currently living in Germany and I have found 3 of these bugs in my house this spring. The first one was on the bathroom floor and was all dried up and dead when I found it like it had fallen out of a crack. The other two were alive and crawling around, one upstairs and one down, in hallways when I found them. I have not seen any for a month, but worry if it is some sort of harmful bug. We do have a dog and small children.
Thanks!
Margie Lucas

Hi Margie,
Stink Bugs or Shield Bugs from the Family Pentatomidae are harmless to humans and pets, but they do emit a disagreeable odor. They also seek shelter inside homes to hibernate over winter, which is probably why you have recently found them.

Letter 8 – Stink Bug

Strange Beetle- White back
Attached is a picture of a bug that we found in a hotel in Canmore, Alberta on December 31, 2006. Any idea what it is? Thanks,
Brad and Megan

Hi Brad and Megan,
This is not a beetle, but a Stink Bug, probably in the genus Perillus.

Letter 9 – Stink Bug

Banasa Stink Bug
August 11, 2009
I found this stink bug on my porch in upstate NY (near Albany) in late June. I identified it through bugguide.net as Banasa Dimiata, a species of stink bug. I hadn’t seen this species on your site in a few years, so I thought you might like the picture!
Naomi
Albany, NY

Hi Naomi,
Thanks for sending us your excellent photo of Banasa dimiata, a Stink Bug represented on BugGuide.

Letter 10 – Stink Bug

Please Identify This Bug that Keeps Breaking Into My House
January 27, 2010
We just moved into a house in Frederick, Maryland that is over one thousand years old. It’s January so I’m not sure where this bug keeps coming from. So far (sorry to say this) I’ve killed 5 of these in just one week in the back bedroom. Last night one “attacked” us while we were sleeping in the front bedroom. I caught one today to take pictures of and then let it go (after reading some on your site). I dont like killing bugs but I want to keep these guys outside…any suggestions?
Jeff Z.
Frederick, Maryland

Dear Jeff,
We weren’t aware that there were any homes in Maryland dating to the first millenium.  This is a harmless Stink Bug in the family Pentatomidae.  Stink Bugs often enter homes to hibernate when the weather cools.  They will not harm your home, its furnishings, nor its inhabitants.

I’m very sorry to misinform you.  In all the madness of moving in my brain messed up the math… The house is over 100 years old (1850-1900 were the dates given).
Thank you very much for the information and quick responce!
Sincerely,
Jeff Z

Letter 11 – Stink Bug

unknown bug
Location: Thorold… near Niagara Falls
July 12, 2011 12:52 am
I LOVE your website and I tried to identify this bug but to no avail. I live in Thorold Ontario, it is summer and he was hanging out on my bathroom window near the back porch light. I have never seen this bug before and love his green pyramid on his back. Thanks for all your hard work!! I have identified many bugs because of you!
With appreciation,
Tracey Ross
Signature: Tracey A. Ross

I found the bug! It was a stink bug!! Thanks anyway!
Tracey

Hi Tracey,
We are happy you were able to self identify your Stink Bug.  Should you care, we can also provide the species identification.  It is Banasa dimiata, based on photos posted to BugGuide.  We will be out of the office for several days at the end of the week, and we are post dating your submission to go live on Friday.

Letter 12 – Stink Bug

Art Center Design 2 (Cole Case’s class) Bug Question
On Nov 17, 2011, at 12:31 AM
Hello Mr. Marlos,
My name is Pei and I’m currently taking Cole Case’s Design 2 class. For a 3D abstraction project, I need to identify this bug and Cole said you might be able to help me.
From the research I’ve done, I am guessing it could be in the Miridae or Pentatomidae families. What do you think?
The underside is a medium value, neutral tan color and the outer shell is a sort of iridescent reddish brown. The shell is shield-shaped and has a large triangular shape on the top.
Thank you for your time and I hope to hear from you soon! 🙂
Pei

Hi Pei,
Say hi to Cole.  Does he want to partner with my class?  I believe this is a Stink Bug in the family Pentatomidae (see BugGuide).

Letter 13 – Stink Bug

Whats this bug!!!!
Location: Puerto Rico
December 4, 2011 9:36 am
Hey I’m doing a proyect about animals and I was wondering the name of the species of this bug. I found it at Puerto Rico. at night soo please replay as soon as possible thank you very much 😀
Signature: Jenny

I’ve found the name s Loxa viridis!
Jenny

Hi Jenny,
Congratulations on finding your own identification.  We were going to suggest that it might be the Stink Bug Loxa flavicollis, which is the only member of the genus represented on BugGuide.  According to BugGuide the type locality is Jamaica.  We cannot say for certain which of these two species is the actual correct identification, however, we are confident that we have both properly identified the genus.

Letter 14 – Stink Bug

Subject: Need help identifying bug!
Location: Chicagoland, IL
December 19, 2013 6:52 pm
I work at a library and we had a program the other evening where we made centerpieces out of live greenery. When one of the people pulled their greenery apart, they found this little guy/girl. I have no idea what kind of bug it is or what to do with it. I can’t turn it loose outside because of the wintery weather. Right now, I’ve got it in a jar with some of the greenery (juniper) it was crawling on. First, I’m wondering: what is it? Second, what should I do with it?
Signature: Librarian M

Dear Librarian M,
This is a Stink Bug in the family Pentatomidae, and we are uncertain of the species.  We cannot even say with any certainty that it is a native species.  Where did the greenery come from?  If it came from a florist or wholesaler, it may be imported from a distant land.  You do not want to introduce a nonnative, potentially invasive species to Chicago, so we would encourage you not to release it.  You can try to keep it alive by keeping fresh greenery with it.  If it was found on a specific plant, chances are good that is a plant it feeds upon.  Stink Bugs have mouths designed to pierce and suck fluids and most feed on the nutritious fluids they obtain from plants.

Letter 15 – Stink Bug

Subject: Bedbug or no?
Location: Orlando
February 27, 2016 8:50 am
There’s debate on if this is a bedbug? Location is Central Florida it is 60 degrees out and it was found in my girlfriends hair this morning. There is debate on if it’s a bedbug.
Signature: Bedbug Boogyman

Dear Bedbug Boogyman,
You are going to have to change your name to Stink Bug Boogyman as this is not a Bed Bug.  Bed Bugs do not have wings.  We suspect this Stink Bug accidentally flew into your girlfriend’s coif.

Letter 16 – Stink Bug Bites Diner at KFC in Australia

Subject: Am I now to evolve into one?
Location: Brisbane City Australia 4000
November 21, 2013 3:00 pm

So. Yesterday

well you see. I live in Brisbane

Anyway. I wanted a KFC chicken leg

You know Kentucky Fried with the eleven herbs etc

Well I Sat on a chair at the Transit centre eatery Roma street

Felt a sharp pain like glass

thought to myself. well. I’m sitting in a chair ,,,so I ignored it. Till!

Ouch

reaching around at my but and crunch!

stood bolt upright and looked at the chair. Nothing ?

It was then I saw it move

A bug on the weave of the chair

It’s grey colour didn’t disguise it.

After I looked up

I then took some photos of it

* i’ve then called out to the clearer

She snapped up the bug with a napkin

Said sorry about that and went to walk away

• I said hey I’ll have that

She put a handout and dropped the serviette into mine

It was then I got a close-up look at the bugger as I unwrapped him. Ok and or her

Not yet dead but is now

So yes I still use still have this bug (not living)

And even now using my iphone and with a double tap on in the screen the close up images of this thing give me the creeps

Tell me

Am I now to evolve into one?

Lol

Signature: Wes

Dear Wes,
This is an immature Stink Bug, and we are not certain of the species, but you may search the Brisbane Insect website to determine a more specific identity for the culprit.  We are amused that your clearer snatched the critter away.  Perhaps she was worried about litigious action against KFC.  Generally, we state that Stink Bugs are harmless, but we have heard it said that “If it has a mouth, it can bite.”  Stink Bugs have mouths designed for piercing and sucking nutrients, generally from plants, but your first hand experience indicates that they might bite humans.  We did assume you were human.  Can you please clarify that.

Thanks for the info Daniel aka Bug Guy
To answer you question till this point I do receive a lot of feedback to the contrary as to my being
How ever I am alive and in the land of the living
And. I will most defiantly solider on
Guess I will let “The Bug Thing” rest for now
My bite. As you say it must be ,has healed without No marks
Took a day and a bit
But. Hey. I’m cool
Thanks again
Wes – Brisbane

Letter 17 – Stink Bug Eggs

Subject: Egg cluster
Location: Seattle
July 22, 2017 4:38 pm
Help me identify this egg cluster found on a smoke bush plant in Seattle.
Signature: Chris

Dear Chris,
These are the eggs of a Stink Bug in the family Pentatomidae, but we are not certain of the species.  Here is a BugGuide image for comparison.

Letter 18 – Stink Bug enters home

Subject: Bug
Location: Columbus, OH
December 29, 2013 7:15 pm
What kind of bug is this? I’m in Columbus, OH and it’s winter. This is the third one I’ve seen in two days in my house. 2 in my upstairs bedroom & one in my downstairs living room.
Signature: Jess

Hi Jess,
This is a Stink Bug in the family Pentatomidae, and Stink Bugs often enter homes to hibernate when the weather cools.  Your photo lacks critical clarity, but we believe this is a Brown Marmorated Stink Bug, Halyomorpha halys, an invasive, exotic species from Asia that is spreading in North America.  More information on the Brown Marmorated Stink Bug can be found on Field Crop News.

Letter 19 – Stink Bug Exuvia

Subject:  Weird Bug!
Geographic location of the bug:  Connecticut
Date: 08/25/2021
Time: 04:36 PM EDT
Your letter to the bugman :  What is this bug? I can usually identify bugs after some searching but this one has me stumped.
How you want your letter signed:  Kat

Dear Kat,
This isn’t really a bug.  It is the shed exoskeleton or exuvia of a Stink Bug.  Here is a similar image from BugGuide.

Letter 20 – Stink Bug and newly hatched Hemipterans from Brazil

Subject:  family coreidae? WhatsApp sp.?
Geographic location of the bug:  Brasil Rio de janeiro
Date: 10/05/2017
Time: 12:04 PM EDT
Hey, whats that? Am i Right???? But whats the specie???
How you want your letter signed:  Loan

Dear Loan,
Are you certain the hatchlings are the same species as the adult?  The adult is not Coreidae, but rather Stink Bug family Pentatomidae, and it looks exactly like the individual identified on this You Tube video as “Stinkbug species – similar to Pentatoma rufipes or Euschistus heros” however the striped legs found on your indivdiual and the one in the You Tube video are different from the two species mentioned.  The former is a European species with red legs based on this Nature Spot posting, and the latter has brown legs based on the Insecticide Resistance Action Committee site, so we are confident that neither names species is correct. Your individual looks like this unidentified Stink Bug posted to Insetologia.  Perhaps Cesar Crash will write in with an identification.  The hatchlings might be Coreid Bugs, but we are not certain.

The young one is diferent from the adult MY mistake
Sorry
Att,
Loan Barros

Hey,
Thank you for the return and the family is sure Pentatomidae, i made some research this week.
Thank you and ill return for sure, hugs from brazil

Att,