The brown marmorated stink bug (Halyomorpha halys) is a common household nuisance. This insect does not bite or sting, but it is known for its strong, unpleasant odor released when it is threatened or crushed. Concern arises in late summer and early fall when these bugs congregate on structures to find a warm, sheltered location to overwinter. Understanding the insect’s behavior determines whether spraying is an effective control measure.
Why Indoor Spraying Is Not Recommended
Applying chemical sprays inside your home is not an effective way to deal with stink bugs that have already entered. When temperatures drop, these insects seek out wall voids and attics to enter a dormant state, or overwinter, making them physically inaccessible to surface sprays. An insecticide applied to a wall or window trim will not reach the vast majority of the bugs hiding within the structure.
The most significant risk of indoor spraying is the potential for a massive odor release. When a stink bug encounters a pesticide, it often panics, triggering the release of its pungent chemical compound. This action negates the purpose of the spray, leaving the homeowner with dead or dying bugs and a lingering, foul smell that can permeate the living space.
Furthermore, using residual pesticides indoors introduces unnecessary chemical residues into the home environment. Chemicals like synthetic pyrethroids can persist in household dust for extended periods, potentially causing irritation or other health concerns for sensitive individuals, especially children and pets. Since the bugs are not feeding or reproducing during their overwintering period, the best solution is to avoid disturbing them with chemicals and focus on non-toxic removal.
Effective Exterior Chemical Treatments
Spraying is most effective when used preventatively as an exterior barrier treatment to stop the bugs from getting inside. This application must be timed correctly, ideally in late summer or early fall, when stink bugs begin to aggregate on the outside of homes searching for overwintering sites. Targeting the structure’s exterior at this time creates a toxic residual layer that kills the insects on contact as they attempt to crawl across it.
The most commonly used chemicals for exterior perimeter treatments are residual insecticides, such as synthetic pyrethroids (e.g., bifenthrin, cyfluthrin, deltamethrin). These products are favored because they maintain their toxicity for several weeks after application, providing a lasting barrier against the migrating pests. Professionals often use micro-encapsulated formulations, which are designed to slowly release the active ingredient over time, extending the treatment’s lifespan.
The application must be focused on all potential entry points and aggregation zones on the building. These areas include:
- Window and door frames
- Soffits
- Utility line penetrations
- Foundation cracks
- The eaves of the roof
Thorough coverage of these warm, sun-exposed surfaces, particularly on the south and west sides of the structure, is necessary to create a complete barrier before the bugs breach the exterior.
Non-Chemical Removal and Prevention Methods
Exclusion is the most reliable long-term solution for managing stink bugs. Stink bugs can squeeze through surprisingly small openings, so homeowners should inspect and seal cracks around windows, doors, utility pipes, and siding using a good quality silicone or silicone-latex caulk. Damaged window and door screens should also be promptly repaired or replaced, and vents leading into the attic or crawlspace should be covered with fine-mesh screening.
For bugs already found inside the home, physical removal is the safest and most practical method that avoids triggering the defensive odor. Manual removal can be accomplished using a vacuum cleaner with a disposable bag or by slipping a sock or stocking over the nozzle to capture the bugs before they enter the main canister. The captured insects should be immediately sealed and disposed of outside to prevent the odor from permeating the vacuum itself.
Another effective method for physical removal is submerging the bugs in a container of soapy water. A bucket or jar filled with water and a few drops of dish soap can be placed directly beneath the bug, which can then be gently brushed or flicked into the solution. The soap breaks the surface tension of the water, causing the insects to drown quickly without releasing their foul-smelling secretions.