University of Maryland Extension

Brown Marmorated Stink Bug

Stanton Gill, IPM Specialist
Brown marmorated stink bug adult on coleus foliage

Article Updated: November 2019

Background Information

Brown marmorated stink bug, Halyomorpha halys, was found in Maryland in Washington and Frederick counties in 2002.  Since then, it has spread across Maryland.  Each year, it has expanded its range and is now found in 44 states in the United States.  This invasive species is being moved around by humans by various forms of transportation including cars, campers, mobile homes, railroads, and trucks.  

The brown marmorated stink bug is native to Asia and was introduced into the United States in shipments of trade goods.  It was found and identified in Allentown, PA in 2001, but was sighted back in 1996 in this area and rapidly spread through the counties of Pennsylvania and spilled down into western Maryland.  When it first showed up in Maryland, it appeared to just be a nuisance pest that overwintered in houses and commercial buildings.  As the numbers increased, reaching very high levels in the fall of 2009, we started seeing injury occurring on vegetable and fruit crops in Washington and Frederick counties.  In the summer and fall of 2010, there were major losses of fruit crops (peaches and apples) in Washington County.  They were also found feeding on grapes, sweet corn, soybeans, tomatoes, peppers, cucumbers, and eggplants.

In the nursery, we have observed them feeding on crabapple trees, cultivated apple trees, zelkova, and hibiscus.  On nursery plants, they tend to feed on the main trunk and major branches.  As BMSB feed, they extract sap. Often, wasps will move in to feed on the sap expelled by the tree through these feeding wounds.  At this point, University researchers are investigating the long-term damage to ornamental woody plant material.  Penn State Extension has reported that brown marmorated stink bugs feed on maple, serviceberry, birch, butterfly bush, pecan, catalpa, hackberry, redbud, citrus, dogwood, fig, sunflower, honeysuckle, apple, plum, pear, rose, lilac, linden, and viburnum.  It has been confirmed feeding on several herbaceous plants including snapdragon, hibiscus, mums, zinnias, sunflowers, and Baptisia.  The stink bugs appear to be highly attracted to amaranth plants which possibly could be used as a trap plant.

In addition to causing damage to plants and fruit, brown marmorated stink bugs are a major nuisance to people.  Adult stink bugs often seek shelter inside houses and other buildings.  Once inside, they congregate almost anywhere.  These pests will not cause structural damage or reproduce in homes.  They do not bite people or pets.  Although they are not known to transmit disease or cause physical harm, the insect produces a pungent, malodorous chemical and when handling the bug the odor is transferred readily.  Some fruit orchard workers have reported a slight allergic reaction to the chemical given off by this bug.  

Brown marmorated stink bug mid instar nymph
Brown marmorated stink bug on tomato

Identification and Biology
Approximately 25-30, elliptically-shaped eggs are often laid on the underside of leaves in summer and are a light green color.  Brown marmorated stink bugs have five nymphal stages, or instars, and range in size from 2.4 mm to 12 mm in length.  First instar nymphs are more brightly colored with red and black. They are not very active and remain around the hatched egg mass. 

Nymphs have dark reddish eyes and a yellowish-red abdomen that is also striped with black.  The legs and antennae of the nymphs are black with white banding.

Adults are approximately 15 - 17 mm (½ inch to 5/8 inch) long with a mottled brownish gray color.  The next to last (4th) antennal segment has a white band and several of the abdominal segments protrude from beneath the wings and are alternatively banded with black and white.  The underside is white, sometimes with gray or black markings.  The legs are brown with faint white banding.
Recently hatched brown marmorated stink bug nymphs still by egg mass
Recently hatched BMSB that were found on hydrangea

Situation in 2012

In 2010 and 2011, brown marmorated stink bugs (BMSB) were seen in extremely high numbers in the Mid-Atlantic region.  They were responsible for causing major economic damage to fruit and vegetable crops at a number of orchards and farms.  Brown marmorated stink bug populations were significantly lower in 2012.  In the late summer of 2011, weather conditions were unfavorable for the BMSB.  Heavy rainfall in early September 2011 from tropical storms reduced the population of nymphs in the fall with fewer overwintering adults present in the majority of residences in Maryland.  The winter of 2011 to 2012 was very mild with warm periods interspersed with cold periods.  The overwintering adult stink bugs came out of their overwintering sites during the warm periods using up valuable body food reserves causing a fair amount of mortality in overwintering populations.  In the spring of 2012, the number of adult BMSB found in home gardens and in fruit plantings was much lower.  We had reports of nymphs and adults feeding on home planting of blackberries, raspberries, and vegetables during the summer of 2012, but in most cases, the populations were not at highly damaging levels.  Each year in the fall, we receive reports of BMSB becoming a nuisance as they move into homes to overwinter. When the weather turns cool at night, adult brown marmorated stink bugs look for overwintering sites and can be found on the outsides of buildings or inside near doors, windowsills, and other entry points.  They can also be found in leaf litter and vegetation outdoors. People who turn on outdoor light systems are reporting clustering of adults in the area under the lights.  These stink bugs are highly attracted to artificial lights in September. Since 2012, population levels have been lower throughout Maryland with reports of high numbers occasionally in different areas. University of Maryland Extension researchers continue to monitor closely for brown marmorated stink bugs for increases in the population for potential heavy damage to fruit and vegetable crops.

Control Options

Physical Control:
Adult brown marmorated stink bugs can enter homes through cracks and crevices.  A few simple tips to help keep them from entering homes are:

  • Caulk windows inside and out.
  • Weather strip entry doors and/or install door sweeps if daylight is visible around the perimeter of the door.  
  • Rake away all debris and edible vegetation from your home’s foundation to keep from  attracting pests.  
  • Inspect for and seal foundation cracks to block a potential point of entry.
  • Secure crawl space entries.  
  • When insulating exposed plumbing pipes around the foundation or the crawl space of your home, caulk small gaps and fill larger ones with steel wool.  
  • If your home has a fireplace, cap or screen the top of the chimney to keep out pests.  
  • Both live and dead brown marmorated stink bugs can be removed from interior areas with the aid of a vacuum cleaner, but the vacuum may smell of stink bugs for a period of time.  Although aerosol-type sprays and foggers labeled for domestic stink bugs will kill these pests in living areas, it will not prevent more of the insects from emerging from cracks after the room is aired out.  Use of these materials is not a solution for long-term management of stink bugs.  

Blue or black fluorescent lights attract the brown marmorated stink bug.  Several available light traps use these color spectrums that are available on the market. Indoors, the lights can help reduce the overwintering populations. Outside, the light traps can be used to monitor BMSB populations.

Biological Control:

A study conducted in 2005 found less than 5% of BMSB eggs were parasitized.  In a study by the University of Maryland, researchers reported an increasing number of BMSB eggs being parasitized by native parasites (12 to 29%).  It is very good news that native parasites are adapting to this new food source. USDA entomologists were rearing the samurai wasp, Trissolcus japonicas, which is a parasitoid of BMSB found in eastern Asia. Since 2014, these parasitoids have been found in the wild in various states, including Maryland and Virginia. It is likely that these wasps were within stink bug egg masses on cargo from Asia.

Several nursery and landscape managers have reported that native bird species were observed feeding on BMSB.  Chickens and Guinea fowl will feed heavily on nymphs and adults of brown marmorated stink bugs.  In several counties, urban residents are allowed to have a limited number of hens, but not a rooster.  Check with your local county zoning board to for specifics on the situation in your county. 

Chemical Control:
In gardens, pyrethrum or insecticidal soaps can be used to directly contact the bugs and kill them.  These materials have no residual.  For pesticide applications made indoors for overwintering adults there are a limited number of products available.  Professional Pest Control Operators (PCOs) are licensed to apply material in residential homes for control of adult bugs inside a house.  

For more information:

Quarles, William. Integrated Pest Management for Brown Marmorated Stink Bug, The IPM Practioner, December 2015.

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