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. 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.
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.
Several nursery and landscape managers are reporting that native bird species are being observed feeding on BMSB. Chickens and Guinea fowl will feed heavily on nymphs and adults of brown marmorated stink bugs. In several counties, urban resident 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.
Brown marmorated stink bug, Halyomorpha halys, was found in Maryland in Washington and Frederick counties in 2002. Since then it has spread across the State of Maryland. Each year it has expanded its range and is now found in over 32 states in the United States. This invasive species is being moved around by humans by various forms of transportation including cars, camper, mobile homes, railroad and trucks.
The brown marmorated stinkbug 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 have 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 have been feeding on grapes, sweet corn, soybeans, tomatoes, peppers, cucumber 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 they feed they extract sap and often wasps will move in to feed on the sap expelled by the tree through the feeding wounds made by the brown marmorated stink bugs. At this point, the long term damage to woody plant material is being investigated by University researchers. Penn State Extension is reporting that brown marmorated stink bugs feed on maple, serviceberry, birch, butterflybush, 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.
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, 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.
Adult brown marmorated stink bugs can enter homes through cracks and crevices. A few simple tips to help keep them from entering homes are:
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.
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.