The brown marmorated stink bug (BMSB) is an invasive agricultural pest and a nuisance to homeowners when it seeks shelter for the winter. These shield-shaped insects aggregate on warm, sunlit exterior walls in late summer and early fall, searching for entry points to overwinter inside structures. Their primary defense mechanism is the release of a foul, cilantro-like odor when disturbed. Control efforts must focus on preventing aggregation and removing them without crushing them. This article focuses on strategies to manage and remove these pests from the exterior of your property before they become an indoor problem.
Managing Exterior Attractants
Proactive measures focus on making the area around your home less appealing to overwintering pests by eliminating harborage and light cues. Stink bugs are attracted to light, a behavior known as positive phototaxis, especially the bright white and UV spectrums. Switching exterior lighting, particularly porch and entryway lights, to less attractive yellow or sodium vapor bulbs can significantly reduce the number of bugs congregating near your doors and windows.
Habitat manipulation involves removing debris and dense vegetation that provide shelter and a pathway to the home’s exterior. Stink bugs often hide in woodpiles, overgrown shrubs, and leaf litter near the foundation. Trimming back trees and bushes so they do not touch the house walls eliminates a common bridge for the insects to climb up toward potential entry points.
If your property includes host plants favored by the BMSB, such as fruit trees or specific ornamental shrubs, managing their health or relocating them away from the structure can reduce local populations. The goal is to create a clean, well-lit perimeter that offers no easy access or safe haven for the bugs as temperatures begin to drop.
Non-Pesticide Removal Methods
Physical removal methods are highly effective for existing exterior aggregations and prevent the unpleasant odor associated with crushing the bugs. The “Soap and Water Trap” is a simple and widely recommended technique utilizing a light source and a container of soapy water.
To create this trap, fill a deep container, such as a foil roasting pan or bucket, with water and several squirts of liquid dish soap. Place the trap on the ground near where the bugs are congregating and shine a desk lamp or other light source over the water at night. The stink bugs are drawn to the light, fall into the water, and the soap breaks the water’s surface tension, causing them to drown.
For daytime removal of smaller groups, manual collection is a viable option; the insects can be carefully swept or flicked into a plastic bag or a container of soapy water. Using a dedicated hand-held vacuum or a shop vacuum fitted with a disposable bag is highly effective for quickly removing larger clusters from walls and window frames. Immediately seal and discard the vacuum bag or empty the contents of the canister into soapy water to prevent the lingering odor from contaminating the vacuum itself.
A strong jet of water from a garden hose can temporarily dislodge stink bugs from the sides of buildings or plants. This method only relocates them, so it is best used in conjunction with other permanent removal techniques like the soapy water trap. The key to all non-pesticide methods is to avoid direct physical contact that might trigger the release of their defensive chemical.
Strategic Use of Exterior Insecticides
For persistent or widespread exterior infestations, a targeted application of residual insecticide can create a chemical barrier against overwintering pests. The most effective time for treatment is in the late summer or early fall, just before the bugs begin aggregating on structures to seek winter shelter. Applying the insecticide during this pre-migration period prevents the insects from successfully climbing and congregating on the exterior walls.
Commonly used active ingredients include synthetic pyrethroids such as bifenthrin, permethrin, or cyfluthrin, which are labeled for exterior perimeter treatments. These residual sprays should be applied as a barrier around the foundation, paying close attention to eaves, window frames, door thresholds, and utility penetrations where the insects may gain entry.
Environmental safety is a major consideration when using chemical controls. Avoid spraying near edible gardens, flowering plants that attract pollinators, or areas frequented by pets and children. While insecticides can reduce the number of bugs entering a structure, they are not a substitute for sealing cracks and crevices, and their efficacy diminishes over time due to weather exposure. Choosing to use these chemicals should be reserved for cases where non-chemical methods have been overwhelmed by the sheer volume of the aggregating population.