Named for its smelly odor, especially when stepped on, the brown marmorated stink bug (Halyomorpha halys) is relatively new to the United States. Known by entomologists as BMSB, this invasive species of stink bug is believed to have been brought into the eastern U.S. from China, Japan, Korea, and/or Taiwan in the late-1990s. The odor that stink bugs are know for can also be emitted by the bugs when they are disturbed. Some say it smells like cilantro; others compare it to stinky feet.
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 cause alarm when they appear in numbers on draperies, blinds, or lights, or when they're buzzing around your head. They enter a home through cracks, gaps, and other openings then come into our living areas when they feel the warmth of the interior.
In the home garden and landscape, stink bugs can damage trees, shrubs, and vines. Although they prefer wild plants, stink bugs will eat more than 100 different varieties of vegetation. The stink bug's needle-like mouthpart pierces fruits, seeds, and other plant parts 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.
Brown marmorated stink bugs have bodies shaped like shields, with grayish-brown coloring. This species is readily identifiable by its dark antennae with distinct white markings. Adults are 1/2 to 3/4 inch long. Young stink bugs are similarly shaped but are more rounded and may be black or light green. 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.
4 Ways to Get Rid of Stink Bugs
As pests that are merely a nuisance indoors and do not typically cause significant damage to residential gardens and landscape plants, stink bugs do not commonly warrant chemical treatment, and trying to kill stink bugs is rarely the best option. Insecticides that kill stink bugs have limited effect on stink bug populations and offer short-lived benefits, so chemical treatments must be reapplied frequently. Therefore, infestations in the home usually are controlled with basic removal methods, rather than killing stink bugs.
Vacuum and dispose of any stink bugs found inside the home (or flush them down the toilet). Dead stink bugs can attract other predacious insects like carpet beetles, so it's important to dispose of them quickly.
The simplest way to reduce the number of stink bugs in your home is to catch them by hand and either throw them outside or kill them and dispose of them. However, some people may have skin sensitivity to the bugs; if this is you, wear gloves when handling the bugs. Kill them by dropping them in a bucket or other container of soapy water to drown them.
Set up a simple trap using an aluminum baking pan (or another container made of reflective material). Fill the pan with 1 to 2 inches of water mixed with dish soap. Position a bright light (a clip-on shop light works well) so it shines down onto the bottom of the pan, creating a bright reflection. Stink bugs will fly toward the light and land in the water, where they drown. Traps work only in limited areas, but they can help you eliminate bugs automatically.
Insecticidal spraying by a licensed professional can provide some control of bugs on exterior walls. Because the sun and weather can break down the insecticide, it will only be effective for a few days to a week, depending on the weather. If the bugs do get inside, entomologists strongly recommend against the use of insecticides to kill stink bugs. It is best to follow insecticide-free practices.
What Causes Stink Bugs?
Similar to boxelder bugs and Asian lady beetles, 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.
Adult stink bugs can overwinter under cover of boards, boxes, firewood, brush, leaves, tree bark, and other yard debris. They emerge in spring to feed.
While damage to garden plants is largely cosmetic (not lethal to plants), stink bugs can ruin homegrown crops of fruits and vegetables, as well as some ornamental plants, if they feed in large numbers. Common garden plants they attack include:
- Apple trees
- Cherry, peach, and other stone fruit trees
- Cabbages and other mustard plants
- Snapdragon and columbine flowers
How to Prevent Stink Bugs
The best defense against stink bugs indoors is to inspect your home's exterior to find and seal all cracks and openings larger than 1/8 inch. Caulk around pipes, wires, and other wall penetrations. Repair torn window and door screens, ensure doors and windows close properly, and use weatherstripping that seals all gaps.
Clean up around the yard, particularly during fall, to deprive stink bugs of places to overwinter. Remove leaf piles, fallen bark and branches, and even overgrown weeds, all of which can provide shelter.
If necessary, prevent stink bugs from reaching garden plants by covering them with row covers or fine netting. The covers must be complete, with no holes and no gapping along the ground. Since covers can prevent pollinators from reaching plants, be careful about where and when you use them.
Do stink bugs harm indoor plants?
It is not common for BMSB to harm most indoor plants, but be watchful if you have fruiting plants indoors. Stink bugs typically choose fruit to eat before other parts or non-fruiting plants.
Do stink bugs have predators?
There are no known natural predators of BMSB. They may be eaten by some birds, but this is not a reliable or predictable control method. The odor excreted by stink bugs is an effective deterrent for many potential insect predators.
How do I know if stink bugs are eating my plants?
Stink bug damage on fruit often appears as brown or dead spotting of the skin and in the flesh just below. Leaves develop similar brown or dead spots. Damage to fruit can also take the form of watery lesions and even cat-facing, a puckering of the surface caused by scarring that is grown over as the fruit matures.