The brown marmorated stink bug (BMSB), Halyomorpha halys (Stål), is a newcomer to South Carolina, first appearing in 2011 and now having a wide distribution. While it is considered a pest in its native Asia, it has reached a higher level of pest status in North America. Originally collected in 1998 in Allentown, PA, it now is confirmed in 41 states and part of Canada.
The Mid-Atlantic States have been struggling with the BMSB for many years, and although they are recent migrants to South Carolina, pest management professionals are already reporting large populations on structures and indoors. In areas where they are common, they are serious pests of fruit trees, legumes, corn, garden vegetables and some ornamental plants. The adults usually feed on fruit and the immatures (nymphs) tend to feed on leaves and stems as well as fruit. Heavy feeding on fruit will cause the fruit surface to become depressed, spongy, and often discolored.
In areas where BMSBs are established, they can trespass in the fall into the places where we live, work and play, looking for overwintering habitats. Before entering a building they will congregate on the exterior walls. True to the name of the stink bug group to which it belongs, the BMSB is capable of emitting a strong, foul odor if disturbed.
There are several native stink bugs that may be confused with the BMSB. The underside of the BMSB is brown-gray to bluish-gray in color. It also has rounded edges on their “shoulders” behind the head, and a thin attachment of the mouthpart to the front of the head. There are distinct black and white bands on the antennae. The light-green eggs and the five brightly-colored, orange and black nymphal stages may be more difficult to recognize. If you need help with your identification seek guidance from your local County Extension Office.
Biology and Habits
After overwintering for several months in protected places, the BMSB will appear in the spring and begin mating. Females may deposit nearly 500 eggs in masses of less than 30 over their lifetime, usually on the undersides of leaves. Depending on geographic location, BMSB may have several generations within a season.
Overwintering sites in natural landscapes include dead standing trees with thick bark, like oaks and locust, which provide crevices for shelter. BMSBs are not associated with downed trees or leaf litter on the ground which may be too moist for their survival. In structures, preferred overwintering sites are around windows, baseboards, attics and almost any void space.
The best offense for BMSB is a good defense that focuses on exclusion. For this to be successful you must be proactive about preparing structures before fall weather prompts BMSB to move indoors.
Exclusion includes sealing as many access points into a structure as possible:
• Use weather stripping or other sealers, to reduce small openings around doors, windows, and garages
• Make sure window screening is intact and that it fit tightly into the window frame
• Check screening on openings leading into the structure from eaves, soffits, and attic entry points
• Check plumbing inserts and areas where telephone, cable, and electrical lines enter the building
• Check chimneys to be sure the damper fits tightly in the closed position when not in use
If the outdoor population is high, an insecticide treatment with a product labeled for the target location is an option. Applications should be focused on entry points, and cracks and crevices where BMSBs may hide. These pests are attracted to lights. Insecticide sprays around lighted areas may also help reduce populations. In general, unless treatments are well placed, the insecticide will break down quickly due to sunlight and moisture. Always read the label and follow directions exactly.
Once these intruders find their way indoors, they often can be removed by simply vacuuming them up, and disposing of the vacuum bag in a sealed container. If the problem is larger than a vacuum can resolve, then calling a pest management professional is a good option.
Other Control Considerations
Currently there are several active research programs investigating control strategies for the BMSB including both light and pheromone traps, but neither is available at this time. In the future these may be effective means to monitor for their presence or capture BMSBs to reduce the populations below a pest level. Native and non-native natural enemies of the BMSB also have potential to regulate populations.
If you are interested in the agricultural importance of the BMSB, a good source of more information is www.stopbmsb.org.