Brown Marmorated Stink Bug
Update on Brown Marmorated Stink Bugs - Fall 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. 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.
The good news is that the brown marmorated stink bug populations have been significantly lower in 2012. In the late summer of 2011, weather conditions were unfavorable for the BMSB. Heavy rainfall in early September from tropical storms appears to have reduced the population of nymphs in the fall with fewer overwintering adults present in 2011 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 there were greatly reduced populations of adult BMSB found in home gardens and in fruit plantings. 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. As we move into September of 2012 there are reports of increased activity of adults and nymphs in home gardens. 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.
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.
Parasites of BMSB
A study conducted in 2005 found less than 5% of BMSB eggs were parasitized. In a preliminary study by the University of Maryland, researchers are reporting 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.
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Two egg masses of BMSB: healthy light green eggs (left) and dark colored eggs with parasitic wasps developing inside them (while feeding on and killing the BMSB) (right). On the left an Anstatus parasitoid has just found the BMSB egg mass. On the right a Scelionid parasitoid has recently emerged from a BMSB egg.
Photos: P.M. Shrewsbury, UMD |
Several nursery and landscape managers report that native bird species have been observed feeding on BMSB. Chickens and Guinea fowl will feed heavily on nymphs and adults. In some counties, residents are allowed to have a limited number of hens but not a rooster. Check with your local county zoning board to see what the situation is in your county.
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.
Trapping:
Blue or black fluorescent lights attract the brown marmorated stink bug. There are several light traps that use these color spectrums that are available of the market. They will trap adult BMSB but the significance of the reduction in population is still being evaluated.
By Stanton Gill, University of Maryland Extension Specialist, Nursery and Greenhouse Management
Frequently Asked Questions
What is the story on the brown marmorated stink bug (BMSB)?
The brown marmorated stink bug (Halyomorpha halys) is a new pest in North America. Adult bugs are 5/8” and dark mottled brown. The last 2 antennal segments have alternating light and dark bands. The exposed edges of the abdomen also have light and dark banding. They emerge from overwintering sites from late March through June depending on location. They immediately begin to feed. Females lay clusters of light green, barrel-shaped eggs on the undersides of leaves from June to August. The young bugs (nymphs) are yellowish and mottled with black and red. Older nymphs more closely resemble the adults. There are 5 stages or instars. In Maryland we can have over 2 or more generations a year.
What do they feed on and what kind of damage do they cause?
The host list is long and includes many ornamental plants, fruit trees, vegetables and legumes. The nymphs or young stink bugs tend to feed shallowly, while the adults feed deeply into plant tissue causing more damage. Damage will vary depending on the plant. On leaves it can appear as small stippled areas and/or necrotic areas. On fruit there may be water-soaked lesions, pitting, dimples, catfacing, and/or depressed areas. Adult stink bugs can cause deep feeding injury in fruit such as apples making them unsalable. Damage on vegetables such as peppers and tomatoes appears as cloudy whitish areas in the fruit. On beans and okra there will be wart-like growths and deformation or shriveling of the pods. Early stink bug feeding on corn results in incomplete kernel formation, while later feeding causes kernel collapse and brown discoloration.
How do you manage them in the garden?
Check your local garden center or nursery for early ripening tomatoes (e.g. Early Girl) or determinate (short) varieties (e.g. Celebrity). It was widely reported in 2010 that the tomato cultivar Juliet was relatively resistant to feeding injury. Gardeners should become familiar with what the bugs look like in all life stages from egg to adult. Hand-pick and/or knock bugs into a container of soapy water to control them. In areas where populations are high, diligence is necessary because of constant migration into the garden from surrounding landscapes and wooded areas.
How do you keep them out of your house?
These stink bugs have also become a tremendous nuisance in homes and buildings as they seek shelter in the fall much like Asian lady bird beetles and boxelder bugs. Prevent them from coming in the home by sealing up cracks with caulk, use weather stripping around doors and windows, remove window air conditioners, and close all possible entry points. Inside shop- vacuum up the bugs and place in an outdoor trash receptacle. It should be noted that if many of them are squashed or pulled into a vacuum cleaner, their odor can be quite strong.
What insecticides control the stink bugs?
We do not recommend insecticides for controlling brown marmorated stink bugs because:
- Most are ineffective
- Some are broad-spectrum and will kill beneficial insects like honeybees and predators that eat pest insects.
- Use of broad-spectrum insecticides can lead to secondary pest outbreaks such as spider mites.
- They pose human and environmental health risks.
Should you choose to try an insecticide to control the stink bugs read the label carefully. The plant (site) or the bug must be on the label! Follow all safety precautions.
What are researchers doing to help with the problem?
Very detailed studies on biology (including environmental cues for aggregation), control options, pheromone studies on pheromones, mass trapping, and biological control are currently being conducted by researchers at the USDA and Land Grant Universities. BMSB was introduced into this country without its natural enemies and therefore has no natural control mechanisms to keep populations in check. Biological control shows the most long term promise for eventual control/management of this pest. Research is underway to identify egg parasitoids that will aid in control of BMSB. Studies are being conducted at the USDA’s Biological Control Research laboratory and it is hoped that in approximately 3 years parasite releases will begin. For additional information read:
- Pest Alert Brown Marmorated Stink Bug Fact Sheet
- Rutgers University Marmorated Stink Bug FAQ and web site.
Report sightings at the Rutgers University BMSB web site www.rce.rutgers.edu/stinkbug/report.
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MDA Press Release - June 22, 2011
MDA Alerts Consumers to Take Care when Using Pesticides to Control Stink Bugs
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Photo Gallery
Click here to compare BMSB immature through adult stages
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Eggs |
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Eggs and newly hatched 1st instar nymphs
(Michael Raupp, UMD) |
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First instar stink bug nymphs
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Nymphs on trumpet creeper
(Penn. State, Entomology) |
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Brown marmorated stink bug nymphs and adult on crabapple
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