Stink bugs are a common nuisance across Kansas, especially in fall when they migrate indoors by the hundreds or even thousands to ride out winter. The brown marmorated stink bug, an invasive species from Asia, has become the most recognized culprit, though several native species also show up in Kansas homes and gardens. Whether you’re dealing with a home invasion or crop damage, here’s what you need to know.
Why Stink Bugs Swarm Kansas Homes in Fall
As days get shorter and temperatures drop, adult stink bugs start congregating on plants near buildings. On warm, sunny afternoons in September and October, they take flight toward structures, landing on sun-warmed exterior walls. From there, they squeeze into any gap they can find: cracks around windows, doors, roof flashing, vents, fascia boards, chimneys, and window air conditioners. Despite their relatively bulky appearance, stink bugs have flat bodies that let them slip through surprisingly tight openings.
They prefer the upper portions of buildings, often entering through attics first. Once inside, they settle into walls, ceilings, and other cool, dry crevices to wait out winter in a dormant state. Buildings in poor repair with many gaps are the most vulnerable. In those cases, stink bugs can enter by the thousands. They aren’t breeding or feeding indoors. They’re simply hiding. On warmer winter days, though, some will wake up and wander into living spaces, which is when most homeowners notice them.
Are They Dangerous?
Stink bugs don’t bite, sting, or transmit diseases. They aren’t poisonous to humans or pets. If a curious toddler or dog chews on one, the bug releases a foul-tasting liquid that can cause mild mouth irritation, stomach upset, or vomiting, but nothing serious. The real problem is the smell: when disturbed or crushed, stink bugs release a pungent odor from glands on their abdomen. In large numbers, crushed bugs can also stain furniture and fabrics with their secretions.
How to Keep Them Out
Prevention is far more effective than trying to deal with stink bugs once they’re already inside your walls. The goal is simple: seal every crack before September.
- Caulk exterior gaps. Focus on windows, doors, soffits, fascia boards, and anywhere pipes or wires enter the building. Pay special attention to the upper portions of your home, since stink bugs tend to land high.
- Check screens and vents. Repair torn window screens, cover attic vents with fine mesh, and seal around window air conditioners.
- Seal interior openings. If bugs are getting into your walls but you can’t stop them at the exterior, caulking around outlet covers, switch plates, ceiling light fixtures, and heat ducts can at least keep them from entering your living space.
If you spot large aggregations on a host plant near your home, an insecticide treatment applied directly to that plant can reduce the population before they migrate to your walls. Finding the exact host plant can be difficult, though. Brown marmorated stink bugs feed on over 170 different plant species, including fruit trees, ornamentals, and vegetables.
Removing Stink Bugs Already Inside
Once stink bugs are overwintering in your walls, spraying insecticides indoors won’t reach them and isn’t recommended. Instead, deal with the stragglers that wander into living areas using simple physical methods.
A vacuum cleaner is the most practical tool. Suck them up and dispose of the bag or empty the canister outside promptly, since the smell can linger. You can also sweep them into a container or pick them up with tissue. A bucket of soapy water works well if you’re knocking them off walls or window frames. Outdoors, a strong jet of water from a garden hose will blast them off siding.
Light traps can also be effective indoors. Stink bugs are attracted to light, so a simple desk lamp positioned over a pan of soapy water in a dark room can catch quite a few overnight. The key rule: avoid squishing them. That’s what triggers the stink, and in large numbers, the secretions leave stains.
Stink Bugs on Kansas Crops
For Kansas farmers and gardeners, stink bugs cause the most concern in soybeans. According to Kansas State University’s entomology department, stink bug damage to soybeans is concentrated in the southeast part of the state. The bugs pierce developing pods with their needle-like mouthparts and feed on the seeds inside, leaving them shrunken and deformed. Treatment thresholds sit at about 10 bugs per 30 feet of row, and infestations are often localized enough to spot-treat rather than spray entire fields.
In home gardens, stink bugs feed on tomatoes, peppers, beans, corn, and many fruit crops. The damage shows up as dimpled, discolored spots on fruit where the bug inserted its mouthparts. The fruit is still safe to eat but cosmetically damaged.
Telling Pest Stink Bugs From Beneficial Ones
Not every stink bug in your garden is a problem. The spined soldier bug, a native predator, looks similar but actually eats caterpillars, beetle larvae, and other pests. Two features set it apart. First, look at the “shoulders” (the front corners of the shield-shaped plate behind the head). On spined soldier bugs, these come to sharp, prominent points. On plant-feeding stink bugs, the shoulders are rounded or only slightly angled. Second, watch how it feeds. Predatory stink bugs extend their mouthparts forward to stab prey, while plant feeders point their mouthparts downward into plant tissue.
If you see a stink bug actively impaling a caterpillar, leave it alone. It’s doing you a favor.