The brown marmorated stink bug (Halyomorpha halys) is native to parts of Asia and was first observed in the U.S. in Allentown, PA in 2001. It took up residence in parts of Washington County and has steadily migrated to other parts of Maryland. Adults congregate in late summer/early fall and actively seek safe overwintering sites- especially inside buildings. Then they emerge and mate in spring. They are not harmful to people, houses, or pets. They do not bite, sting, suck blood, or spread disease and they don’t eat or bore into wood. The BMSB feeds on plant leaves, buds, and fruits.
Inside your home
Typically, stink bugs will emerge from cracks under or behind baseboards, around window and door trim, and around exhaust fans or lights in ceilings. Mechanical exclusion is the best method to keep stink bugs from entering homes and buildings. First, attempt to locate the openings where the insects gain access. Cracks around windows, doors, siding, utility pipes, behind chimneys, and underneath the wood fascia and other openings should be sealed with good quality silicone or silicone-latex caulk. Damaged screens on doors and windows should be repaired or replaced.
Keep these points in mind when choosing a method for controlling BMSB:
- The BMSB is a strong flier and will quickly “drop” downward when disturbed.
- They emit a strong, unpleasant odor when threatened or crushed. The smell goes away quickly.
- They are more sluggish on cool, overcast days.
- They tend to congregate late summer/fall on warm, elevated surfaces.
- Pesticides are generally ineffective and not recommended for controlling this pest inside or outside your home.
Non-toxic techniques that are working
Sucking them up with a dry or wet vac is efficient. The bugs will cause the collection canister or bag and other parts of your machine to smell, but the odor is temporary. Some people have solved this issue by slipping a knee-high stocking over the outside of their vacuum tube and securing it with a rubberband. The stocking is then stuffed into the tube and captures the sucked up bugs before they get into the canister or bag. Turn off the vacuum to empty the bugs into a container of soapy water.
Sweep the bugs into a container of soapy water. Cut the top off a straight-sided plastic container-½ gallon to 1 gallon size. Fill the bottom ¼ of the container with water mixed with a teaspoon of liquid detergent or soap. Place your hand, a piece of cardboard, or whisk broom over top of the bugs wherever they are in your home and sweep them down into the container. Or slide the container up a wall, window, or drapes where bugs are resting to get them to drop down into the soapy water. They cannot escape and will eventually drown. You can attach your container to a pole or broom handle to reach high locations.
There are insecticides, available to individuals, that are labeled for controlling indoor pests. The question to ask: Is spraying a harmless, nuisance pest worth the expense and trouble, and exposure of people and pets to toxic chemicals?
Aerosol-type insecticide foggers are not recommended for use indoors to kill stinkbugs that have amassed on ceilings and walls in living areas. They will not kill all of the stink bugs or prevent more from entering your home. Spraying insecticides into cracks and crevices will not prevent the bugs from entering living areas and is not a viable or recommended treatment.
It is not advisable to use an insecticide inside after the insects have gained access to the wall voids or attic areas. Although insecticidal dust treatments to these voids may kill hundreds of bugs, there is the possibility that carpet beetles will feed on the dead stink bugs and subsequently attack woolens, stored dry goods or other natural products in the home.
Outside your home
You can sweep the bugs into containers as mentioned above. This can be effective when the bugs are easy to access and have congregated in large numbers. Spraying the bugs with a stream of water will dislodge them but they will probably return.
Exterior applications of insecticides may offer some minor relief from infestations where the task of completely sealing the exterior is difficult or impossible. However, insecticide applications are expensive, pose health and environmental risks, and will not necessarily produce good results. Therefore, we generally do not recommend using insecticides to manage this pest.
If you choose the spray route, applications should be made with a synthetic pyrethroid (i.e. deltamethrin, cyfluthrin, lambda-cyhalothrin, cypermethrin, sumithrin or tralomethrin) and should be applied by a licensed pest control operator in the fall just prior to bug congregation. Unfortunately, because insecticides are broken down by sunlight, the residual effect of the material will be greatly decreased and may not kill the insects much beyond several days or a week.
Do-it-yourself pesticide applications
There are several insecticides that are available in garden centers, hardware stores, and home improvement stores that are labeled for application to the exterior of structures. Look for registered insecticides that are labeled to be applied around window sills and door thresholds which are points of entry for this insect (using any other types of insecticide on the outside of your house could discolor or damage the finish.) Do not apply insecticides to the house foundation or mulch.
Some insecticides are ready-to-use (RTU) products. This means that the active ingredient has been mixed with water in the correct amount and can be directly sprayed from the container without further mixing or preparation. Other products are “concentrates” meaning that you will have to measure out the insecticide and mix it with water in your own sprayer.
You MUST always follow all label directions. Again, spraying insecticides to control BMSB on the exterior of your home is expensive, marginally effective, and not generally recommended.
Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place.
Portions of this tip sheet were adapted from an on-line fact sheet by Steve Jacobs, Sr. Extension Associate for Penn State Extension: http://ento.psu.edu/extension/factsheets/brown-marmorated-stink-bug