If your home suddenly becomes a magnet for stink bugs every September, you’re experiencing a predictable and preventable biological event. It’s a common issue that can be frustrating for homeowners.
The reason for this sudden invasion is simple: stink bugs are attracted to your house because they are seeking a safe, insulated place to survive the winter. This behavior, triggered by decreasing daylight and cooler temperatures, is a form of insect hibernation called diapause. They are drawn to your home by its warmth, light, and the countless small entry points it offers. This guide explains these attractants in detail and provides a professional plan to keep them outside where they belong.
The “Why”: Understanding the September Invasion
The Brown Marmorated Stink Bug, an invasive species in North America, spends the summer feeding on plants. As summer wanes, their internal clock tells them to find shelter to overwinter. A house, with its stable temperatures and protection from the elements, is the perfect five-star hotel. They aren’t looking for food in your home; they are strictly seeking refuge.
The Key Attractants: Why Your House Was Chosen
Stink bugs use a few key signals to find a suitable overwintering site.
* Warmth: On cool, sunny autumn days, they will congregate in large numbers on the sunniest (and therefore warmest) sides of a house, typically the south- and west-facing walls. The heat radiating from the structure signals a stable environment.
* Light: At night, interior lights shining through windows and exterior porch lights act as powerful beacons, drawing them in from surrounding areas.
* Structural Features: Stink bugs are attracted to prominent features that offer an easy place to land and search for entry. This includes light-colored siding, strong rooflines, and chimneys. More importantly, they are looking for the tiny cracks and crevices that exist on every home.
Common Entry Points: How They Get Inside
A stink bug can flatten its body to squeeze through surprisingly small gaps. The most common entry points we find in the field are:
* Gaps around window-mounted air conditioning units.
* Torn window and door screens.
* Unscreened attic, gable, and soffit vents.
* Cracks where siding meets the foundation.
* Gaps around exterior pipes, faucets, and utility lines.
* Slightly open chimney flues.
The Field-Tested Prevention Plan
The only truly effective long-term solution for stink bugs is physical exclusion.
#### Phase 1: The Exterior Lockdown
This is the most critical phase and should be completed in late summer, before the bugs start moving.
1. Seal All Gaps: Use a high-quality silicone or silicone-latex caulk to seal any cracks around windows, doors, siding, and utility entry points.
2. Repair Screens: Meticulously inspect and repair any holes or tears in all window and door screens.
3. Check Vents: Ensure that all vents (attic, soffit, bathroom, etc.) are properly screened with hardware cloth.
4. Install Weather Stripping: Replace worn or missing weather stripping around doors and windows to create a tight seal.
#### Phase 2: Reduce Attractiveness
* Manage Lighting: In the evening, draw your blinds to minimize light spillage. Swap out standard exterior white bulbs for yellow “bug lights,” which are less attractive to insects.
* What to Do Indoors: If a few get inside, do not crush them—this releases the foul odor. The best method is to use a vacuum cleaner to suck them up. For ongoing issues, keep a small shop-vac handy. Empty the canister or dispose of the bag outside immediately to prevent the smell from lingering.
FAQ
Q: Do stink bugs bite or cause damage to the house?
A: No. Stink bugs are a nuisance pest. They do not bite people or pets, nor do they cause structural damage to your home like termites or carpenter ants. Their primary negative impact indoors is their presence and the odor they release when disturbed or crushed. Their droppings can, however, stain light-colored surfaces like curtains and walls.
Q: Why are there so many more stink bugs now than there were years ago?
A: The Brown Marmorated Stink Bug is an invasive species, first identified in the United States in the late 1990s. It originated in Asia and has very few natural predators in North America. This has allowed its population to grow and spread virtually unchecked, leading to the large fall invasions we see today.
Q: Will spraying an insecticide on the outside of my house work?
A: A professional application of a residual insecticide by a licensed pest control company can significantly reduce the number of stink bugs that congregate on your home’s exterior. However, this is a temporary solution that requires reapplication and is less effective over the long term than a thorough exclusion plan. Sealing the bugs out is always the better strategy.