Spring Fever: Restless Brown Marmorated Stink Bugs Stumble Forth

Halyomorpha halys is the brown marmorated stink bug (BMSB), a name that is simplified usually 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).

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.

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.

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.

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. BMSBs sometimes release the malodor when they are being touched, moved, or squished.

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.

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

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.

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.

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.

BMSBs are known affectionately as "marmies" in my home. My house marmies wander wherever they please throughout the year. Oftentimes, they alert my family to their presence by alighting on the TV screen or on our hands while we are watching movies. We have never known them to exude any kind of odor.

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.

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Heraldic shield shape characterizes members of insectile superfamily Pentatomoidea.: David R. Lance, USDA APHIS PPQ, Bugwood.org, CC BY 3.0 U.S., via Forestry Images @ https://www.forestryimages.org/browse/detail.cfm?imgnum=1460048

"uninvited guest": L'eau Bleue, CC BY-SA 2.0, via Flickr @ https://www.flickr.com/photos/marcbanksphotos/5363552802/

ventral / adaxial / front view of museum specimen: Pennsylvania Department of Conservation and Natural Resources - Forestry, Bugwood.org, CC BY 3.0 U.S., via Forestry Images @ https://www.forestryimages.org/browse/detail.cfm?imgnum=5018057

Carneys Point, Salem County, southwestern New Jersey: Susan Ellis, Bugwood.org, CC BY 3.0 U.S., via IPM Images @ https://www.ipmimages.org/browse/detail.cfm?imgnum=5443485; via Forestry Images @ https://www.forestryimages.org/browse/detail.cfm?imgnum=5443485

Japanese common name: Kusagi kamemushi: Ishikawa Ken (chidorian), CC BY-SA 2.0, via Flickr @ https://www.flickr.com/photos/chidorian/543348571/

female parasitoid wasp (Trissolcus mitsukurii) from Asia; USDA Jan. 23, 2013, photo by Steve Valley: U.S. Department of Agriculture (USDAgov), CC BY 2.0, via Flickr @ https://www.flickr.com/photos/usdagov/8412962654/

emergence of adult parasitoid insect from stink bug egg; photo by Brian T. Cutting; ARS Image Number D2731-1: Public Domain, via USDA Agricultural Research Service (ARS) @ https://www.ars.usda.gov/oc/images/photos/jan13/d2731-1/

BMSBs on peach (Prunus persica (L.) Batsch): Gary Bernon, USDA APHIS, Bugwood.org, CC BY 3.0 U.S., via Forestry Images @ https://www.forestryimages.org/browse/detail.cfm?imgnum=1113016

characteristic white bands on BMSB's legs and antennae: Eric R. Day, Virginia Polytechnic Institute and State University, Bugwood.org, CC BY 30 U.S., via Forestry Images @ https://www.forestryimages.org/browse/detail.cfm?imgnum=5427663

BMSB casts shadow on foliage: Susan Ellis, Bugwood.org, CC BY 3.0 U.S., via Insect Images @ https://www.insectimages.org/browse/detail.cfm?imgnum=5369381

West Side, New York City: Roban Kramer (robanhk), CC BY-SA 2.0, via Flickr https://www.flickr.com/photos/robanhk/6862822610/

Fondazione Edmund Mach, Trentino (Provincia Autonoma di Trento – Trentino), northeastern Italy: Yerpo, CC BY SA 3.0, via Wikimedia Commons @ https://en.wikipedia.org/wiki/File:Halyomorpha_halys_lab.jpg

Heidelberg, Baden-Württemberg, southwestern Germany: 4028mdk09, CC BY SA 3.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Paulownia_tomentosa_-_unreife_Früchte.jpg

Paulownia tomentosa flowers: Brno-Černá Pole, southeastern Czech Republic: Petr Filippov (Don Pedro28), CC BY SA 3.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Paulownia_tomentosa2a.JPG

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