Spring Fever: Restless Brown Marmorated Stink Bugs Stumble Forth

by DerdriuMarriner

As they shrug off their wintry hibernation, brown marmorated stink bugs (Halyomorpha halys) announce the arrival of spring.

Halyomorpha halys is commonly known as brown marmorated stink bug (BMSB) or as stink bug.

An Old World native originally from east Asia, stink bugs were introduced accidentally into the United States in the 1990s, probably in shipping crates.

Rousing themselves in early spring, stink bugs proliferate in the New World where they have no natural predators.

adult brown marmorated stink bug

Halyomorpha halys (Stal)
Halyomorpha halys (Stal)


Halyomorpha halys is the brown marmorated stink bug (BMSB), a name which is usually simplified to stink bug. Native to mainland eastern China, Japan, Korea, and Taiwan, these insects are in the family Pentatomidae (Greek: pente “five” + tomos “section”). This family is so named because their antennae have five segments.

Halyomorpha halys slipped into the United States sometime in the 1990s, probably in shipping crates. Sightings were first reported by college students at Muhlenberg College in Allentown, Pennsylvania in August 1998. The first collection of a specimen occurred in Allentown the next month, September 1998. In all likelihood the first sightings did not constitute the first appearance.

The introduction, albeit accidental, has mushroomed into an invasion. As of September 2010, BMSBs have been noted in 37 of Pennsylvania’s 67 counties. Nevertheless, the Pennsylvania State University College of Agricultural Sciences considers it “probable that they are in all counties” (Steve Jacobs, April 2011).


closeup of adult stink bug on desk inside house

"uninvited guest"
"uninvited guest"


In addition to the nation's capital, Washington, D.C., twenty-three states have officially reported BMSB populations:

  • California, Connecticut, Delaware, Florida, Indiana, Kentucky, Maine, Maryland, Massachusetts, Mississippi, Missouri, New Hampshire, New Jersey, New York, North Carolina, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, and West Virginia.


Ten states have reported Halyomorpha halys sightings within their boundaries:

  • Alabama, Arizona, Georgia, Illinois, Iowa, Michigan, Minnesota, Nebraska, Washington, and Wisconsin.

What BMSBs look like


Adult BMSBs are about two-thirds of an inch (17 millimeters) in length.

Their typical shield shape makes their width almost equivalent to their length.

Their antennae, which are in five segments, are black with a white band.

Their underside is pale while the shield part of their body is mottled brown-grey.

Alternate bands of black and white on the laterotergites (abdominal flanges) protrude around the wings, along the lower sides of the dorsal shield, from behind their back legs almost to the membrane, the bug’s pointed tip.

Its generally dark legs are banded in faint white.


closeup of Halyomorpha halys eggs on underside of Buddleia leaf, one of over 300 host plants

Carneys Point, Salem County, southwestern New Jersey
Carneys Point, Salem County, southwestern New Jersey

Instars: five stages from egg mass to adult


Eggs range in color from white to light green.

Halyomorpha halys goes through five nymphal stages, called instars, in their growth from newborn to adult. Length through the stages ranges from 0.1 inches (2.4 millimeters) to about 0.5 inches (12 millimeters).

Instars, which are brightly colored, are more vulnerable than adult BMSBs, which, with their barklike coloring, disappear into their surroundings.

  • Instars have dark reddish eyes.
  • Their yellowish-red abdomen has black striping.

Nevertheless, their legs and antennae, with their black and white banding, resemble those of the adult.


hatching Halyomorpha halys: BMSB first instar

Japanese common name: Kusagi kamemushi
Japanese common name: Kusagi kamemushi

Why they are called stink bugs


The unflattering epithet is derived from the pungent odor that is emitted by the scent glands of Halyomorpha halys. The stench is a defense mechanism to dissuade birds and lizards from devouring them, but BMSBs sometimes release the malodor when they are being touched, moved, or squished.


Research in pest biocontrol:

female parasitoid wasp (Trissolcus mitsukurii) and 3 relatives (T. flavipes, T. halyomorphae, T. plautiae) lay eggs in BMSB eggs and are undergoing 2-year evaluation as potential biocontrol against BMSB by USDA APHIS in quarantine labs in Delaware.
female parasitoid wasp, Trissolcus mitsukurii, from Asia
female parasitoid wasp, Trissolcus mitsukurii, from Asia

Proliferation factors


Without any known natural enemies in the United States, BMSBs proliferate easily and remain unvanquished.

Unseasonably warm seasons, as occurred in Pennsylvania in 2010, promote the development of two or three generations, instead of the normal one generation per year. In contrast, four to six generations per year are recorded in subtropical parts of China. As Penn State entomologist Steve Jacobs observed:

. . .this year’s warm spring and early summer allowed the stink bug to reproduce at a faster pace. Normally, you’d see one generation of stink bugs per growing season, but this year, we’ve had three generations, leading to higher and faster-spreading populations.

Decimation by pesticide/insecticide application is not recommended for many reasons. Importantly, these compounds do not evince significant residuality, which means that immigrants after spraying are unaffected and therefore rapidly repopulate.

The brown marmorated stink bug population is controlled in Asia by a natural enemy, a parasitic wasp that attacks stink bug eggs. Introduction of this natural control from Halyomorpha halys’ native region in Asia into their naturalized range in the United States entails a lengthy process of quarantine and study and may or may not prove desirable or viable.


Adult parasitoid insect emerging from stink bug egg:

after female wasp lays egg into stink bug egg, parasitoid offspring (one per egg) develops inside egg, eating it from inside out.
emergence of adult parasitoid insect from stink bug egg
emergence of adult parasitoid insect from stink bug egg

Favorite foods


It is estimated that BMSBs gorge on 300 host-plant species that range from apples and peaches to blackberries to corn, lima beans, green peppers, soybeans, and tomatoes.


adult brown marmorated stink bugs on a peach (Prunus persica)

Host: peach (Prunus persica (L.) Batsch)
Host: peach (Prunus persica (L.) Batsch)

Cat-facing insects


Cat-facing insects such as Halyomorpha halys cause unattractive deformities, dimples, and scars by feeding on the surface of crops, especially fruits.

The term "cat-facing" derives from the similarity of fruit distortions to a cat's puckered face.

Cat facing occurs because of their piercing-sucking style of feeding. Piercing the skin of the crop with their mouthparts, they then inject saliva and suck out the juices. Although their direct contact with the crops and the salivary orts that they leave apparently are innocuous to humans, the external injury as well as the internal dehydration prohibit marketability as produce. Damaged fruit can be downgraded for processing as juice, for example, but the sale price drops dramatically to one-third to one-tenth of the value that is achieved with whole, undamaged fruit.

BMSBs are considered to be serious agricultural pests, attacking crops vigorously in mid-summer to early fall (July to September) as the crops near maturity. The Mid-Atlantic region has expressed concern over damage to crops from marauding brown marmorated stink bugs.


closeup of late instar nymph on soybean leaf (Glycine max L. Merr.):

characteristic white bands on BMSB's legs and antennae
Host: soybean (Glycine max (L.) Merr.)
Host: soybean (Glycine max (L.) Merr.)

BMSB lookalikes


The term “stink bug” is not exclusive to BMSBs. It is applied to similar looking, native species. BMSBs are differentiated from lookalikes by the black and white banding on their abdomen along the wings, by their white-striped antennae, and by their speckling.


brown marmorated stink bug crawling on foliage

Image location: New Jersey
Image location: New Jersey

Homesteading cycle


From September through mid-October, adult BMSBs search for their winter lair. Popular overwintering sites for them are inside homes, where they snuggle invisibly for the cold months.


spring: face-to-face with Halyomorpha halys

New York City: West Side
New York City: West Side

Spring fever


In late April to mid-May adults emerge, somewhat sluggishly, from their hiding spots. Spring is in the air, and they have spring fever. They are anxious to shake off winter’s inactivity, to identify plentiful food sources, and to think about upcoming mating and depositing eggs, which occupies them from May through August.

BMSBs are being seen increasingly as spring progresses. Just as they are responding to spring’s siren call, so all of the rest of nature, in its floral and faunal forms, is awakening. Of particular interest to BMSBs are the floral rebirths and renewals, for therein lies their food supply.

Inside homes or outside, Halyomorpha halys adults are restless and hungry, and they are throwing caution to the wind. They do not seem to care who sees them at this time of year.


female brown marmorated stink bug from a laboratory colony on a common bean leaf

Fondazione Edmund Mach, Trentino (Provincia Autonoma di Trento – Trentino), northeastern Italy
Fondazione Edmund Mach, Trentino (Provincia Autonoma di Trento – Trentino), northeastern Italy



My special thanks to:

  • Talented artists and photographers/concerned organizations who make their fine images available on the Internet;
  • Virginia Polytechnic Institute and State University for superior on-campus and on-line resources.


fruit and leaves of princess tree (Paulownia tomentosa):

Adult brown marmorated stink bugs tend to feed exclusively on fruit whereas nymphs consume fruits, leaves, and stems.
Heidelberg, Baden-Württemberg, southwestern Germany
Heidelberg, Baden-Württemberg, southwestern Germany

Sources Consulted


Alston, Diane, Michael Reding, and Marion Murray. “Cat-facing Insects.” Utah State University Extension and Utah Plant Pest Diagnostic Laboratory > Utah Pests Fact Sheet Series: Insects – Tree Fruit. October 2010. Utah State University Cooperative Extension. Web PDF. extension.usu.edu

  • Available at: http://extension.usu.edu/files/publications/factsheet/cat-facing.pdf

Hoebeke, E. Richard, and Maureen E. Carter. 2003. "Halyomorpha halys (Stål) (Heteroptera: Pentatomidae): A Polyphagous Plant Pest from Asia Newly Detected in North America." Proceedings of the Entomological Society of Washington, Vol. 105, No. 1: 225 - 237.

  • Available via Internet Archive at: https://archive.org/details/cbarchive_121752_halyomorphahalysstlheteroptera1884

“How to Identify the Brown Marmorated Stink Bug.” Rutgers New Jersey Agricultural Experiment Station > Home, Lawn & Garden. Rutgers, The State University of New Jersey. Web. njaes.rutgers.edu

  • Available at: http://njaes.rutgers.edu/stinkbug/identify.asp

Jacobs, Steve. “Brown Marmorated Stink Bug: Halyomorpha halys.” AgSci > Entomology > Insect Advice from Extension > Fact Sheets. Revised: January 2014. Pennsylvania State University College of Agricultural Sciences. Web. ento.psu.edu

  • Available at: http://ento.psu.edu/extension/factsheets/brown-marmorated-stink-bug

Kamminga, Katherine, D. Ames Herbert Jr., Sean Malone, Thomas P. Kuhar, and Jeremy Greene. Field Guide to Stink Bugs of Agricultural Importance in the Upper Southern Region and Mid-Atlantic States. Blacksburg, VA: Virginia Cooperative Extension, 2009.

  • Available at: http://pubs.ext.vt.edu/444/444-356/444-356_pdf.pdf

Maguire, Ken. “Move Over, Bedbugs: Stink Bugs Have Landed.” The New York Times > U.S. September 26, 2010. The New York Times Company. Web.

  • Available at: http://www.nytimes.com/2010/09/27/us/27stinkbug.html?pagewanted=all&_r=0

"Princess Tree." National Invasive Species Information Center > Plants > Species Profiles. Last modified: November 26, 2013. National Invasive Species Information Center. Web. www.invasivespeciesinfo.gov

  • Available at: http://www.invasivespeciesinfo.gov/plants/printree.shtml

“Researchers Seek Elusive Answers to Stink-Bug Infestations.” Penn State News. September 29, 2010. The Pennsylvania State University. Web. news.psu.edu

  • Available at: http://news.psu.edu/story/164320/2010/09/29/researchers-seek-elusive-answers-stink-bug-infestations


princess tree (Paulownia tomentosa): also known as empress tree or foxglove tree; one of preferred host plants for Halyomorpha halys ~

Native to China and introduced into the United States as an ornamental in the 1840s, P. tomentosa is considered invasive in Connecticut, Georgia, Kentucky, Louisiana, New Jersey, North Carolina, Oregon, Pennsylvania, Tennessee, Virginia, W. Virginia.
Paulownia tomentosa flowers: Brno-Černá Pole, southeastern Czech Republic
Paulownia tomentosa flowers: Brno-Černá Pole, southeastern Czech Republic
the end which is also the beginning
the end which is also the beginning

Stink Bug Canvas Print / Canvas Art - Artist Clarence Holmes

gallery wrapped on 1.5" thick stretcher bars; arrives "ready to hang" with hanging wire, mounting hooks, and nails
Museum Quality Canvas Print

A Stink Bug Trapped in a Bucket of Dried Paint: photo by Brian Gordon Green

A Stink Bug Trapped in a Bucket of Dried Paint

Strube Professional Indoor Stink Bug Trap: As seen on "Animal Planet" ~

Contains a non-toxic glue and an all-natural secret scent that attracts Stink Bugs; Includes a loop to hang the trap, and an internal light bulb with a 6-foot power cord.
stink bug trap light: for indoor use

Do you like BMSBs, allowing them to go their way in peace?

Stainless Steel Travel Mug: "I survived stink bugs" ~

14 oz capacity; easy-grip handle with thumb rest; slide opening lid with slanted drinking surface.
Travel Mug

Garden - Bug Off: Natural-colored t-shirt

Garden - Bug off
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Me and my purrfectly purrfect Maine coon kittycat, Augusta "Gusty" Sunshine

Gusty and I thank you for reading this article and hope that our product selection interests you; Gusty Gus receives favorite treats from my commissions.
DerdriuMarriner, All Rights Reserved
DerdriuMarriner, All Rights Reserved
Updated: 08/12/2014, DerdriuMarriner
Thank you! Would you like to post a comment now?


DerdriuMarriner on 04/18/2014

Mira, Probably you were seeing hawthorn shield bugs (Acanthosoma haemorrhoidale), so-named because they favor hawthorns.
Brown marmies are becoming more visible here, as welcomers of spring. Some overwinter in my home. I just let them be. So does my kittycat Augusta "Gusty" Sunshine ~ although she did eat a dead marmie the other day, crunching with each bite. She ate the whole thing but left the dead one next to it alone. She must have needed some crunch to her diet. :-)

Mira on 04/18/2014

I saw lots of bugs today, so this is timely for me. They had a metallic green back. They buzzed around and on a hawthorn bush. I kept wondering why they were so many! I guess that's springtime for bugs, as you say :)

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