Named for its smelly-foot-like odor when crushed, the brown marmorated stink bug (Halyomorpha halys) is relatively new to the U.S. - but this stinky bug has become a big problem in homes, especially, it seems, in North Carolina. The bug is believed to have been brought into the eastern U.S. from China, Japan, Korea, and/or Taiwan in the later 1990s.
Although stink bugs are becoming more than just a nuisance pest in agricultural areas of the eastern U.S., like squash bugs and boxelder bugs, they are not known to breed indoors, cause interior damage, or harm humans.
But stink bugs can be a real nuisance -- and even alarming -- when they appear on draperies, blinds, lights, or even buzzing around one's head in the home. The bugs enter the home's structure through cracks and gaps, then come into our living areas when they feel the warmth.
The Stink Bug
- Color. Although the brown marmorated is the most common stink bug in the U.S., a green variety of stink bug can also be found in the southeastern and south central states.
- Shape. Stink bugs are shaped like shields and are 1/2 to 3/4 inch long. The young stink bugs are similarly shaped, but more rounded and may be black or light green.
- Behavior. Similar to boxelder bugs, stink bugs will congregate on exterior building walls in the fall, seeking hidden areas in which to overwinter. They can also be a nuisance in the spring as they move further into the home and during summer when they feed on vegetation and crops.
Stink Bug Damage
In the home, stink bugs are little more than a nuisance pest to people because they do not sting or bite, and they don't cause structural damage to homes or buildings.
But, they can cause significant damage to trees, shrubs, and vines, as well as tree fruits, blackberries, corn, beans, tomatoes, peppers, soybeans, and other crops.
Although they prefer wild plants, stink bugs will eat more than 50 different vegetation varieties.
The stink bug's needle-like mouthpart pierces seeds to feed on their nutrients. The amount of damage to the plant is dependent on the developmental stage at which the bug fed. The stink bug can also transmit yeast-spot disease to plants while it feeds.
Stink Bug Control
The stink bug's odor repels many potential predators, but a number of common bird species prey on the insect for food. However, with so few natural predators, the stink bug can become quite obnoxious to humans.
Unfortunately, according to Rutgers University Extension Service, "there are no viable strategies for control of the Brown Marmorated Stink Bug. The use of insecticides has a very short-lived effect and there is evidence of resistance development. Even where insecticide is effective, repopulation occurs through migration from non-treated areas."
For this reason, the best defense against the stink bug is a good offense:
- Home or Building Exterior. Insecticidal spraying by a licensed professional can provide some control of bugs on exterior walls. But, because sun and weather can break down the insecticide, it will only be effective for a few days to a week, depending on the weather. So, the best defense is inspecting your home's exterior to find and seal all cracks and openings, and prevent the bugs from entering. Caulk around incoming pipes, utility wires, and cables; repair window and door screens; ensure door and window seals are intact.
- Interior. If the bugs do get inside, entomologists highly recommend against the use of insecticides. It is best to follow insecticide-free practices and vacuum and dispose of any stink bugs found inside the home (or flush them down the toilet). Because the dead bugs can attract other predacious insects, such as carpet beetles, any insects killed with insecticide would still need to be vacuumed or swept. The bugs do not sting or breed indoors, and, contrary to urban myth, dead stink bugs do not attract other stink bugs--but live stink bugs will emit odors to attract other stink bugs.
- Exterior vegetation. According to the North Carolina Extension Service, "To determine when chemical control is necessary, shake the [soybean] plants on about 1 meter (3 feet) of a row over a muslin cloth and count the number of stink bugs. The economic threshold varies from 1 stink bug per 0.3 meter (1 ft) of a row to 1 bug per 0.9 meter (3 ft) of a row, depending upon state extension service recommendations."
Although this guidance is focused on soybeans, it can be used as a general guideline in determining the extent of a crop infestation.