Quick facts
- Size
- About 5/8 inch long
- Looks like
- Mottled brown shield, white bands on antennae
- Peak season
- September and October entry, spring exit
- Where in Michigan
- Mainly the southern Lower Peninsula, spreading north
- Main risk
- Nuisance, odor, fruit and crop damage
- Risk level
- Low
Signs you have stink bugs
- Brown, shield-shaped bugs on south or west walls on sunny fall days
- Bugs around window frames, doors and siding gaps
- Slow-moving bugs in rooms on warm winter days
- A strong, cilantro-like odor when bugs are disturbed or crushed
- Bugs clustered near light fixtures and windows in late winter and spring
Brown marmorated stink bugs in Michigan
Brown marmorated stink bugs are native to East Asia. They were first detected in Michigan around 2010 and have since spread across much of the southern Lower Peninsula, with reports moving north over time. They feed on many fruits, vegetables and ornamental plants, which is why Michigan's apple, peach and vegetable growers watch them closely.
Homes near orchards, woodlots, soybean and corn fields often see the biggest fall gatherings. In cities and older suburbs they are more scattered but still show up on sunny walls. You can tell them from native stink bugs by the light and dark bands on the antennae and along the edge of the body.
Why stink bugs come inside in the fall
As days shorten in September and early October, adult stink bugs look for protected places to spend the winter. They gather on warm, sunny walls, then squeeze into cracks around windows, siding, soffits and attic vents. Most of them stay in wall voids and attics all winter and you never see them.
On warm winter days, or as spring arrives in March and April, some wake up and wander into living space through outlets, light fixtures and window frames. They do not breed indoors, so the bugs you see in March are the same ones that got in last fall. They are slow and clumsy and often end up on lamps and windows.
How to keep stink bugs out
Sealing is the best long-term fix. Before mid-September, caulk gaps around windows, doors, siding, utility lines and fascia boards. Repair torn window screens and add screen behind attic and soffit vents. This work also helps with Asian lady beetles and cluster flies, which use the same gaps. Start on the south and west sides, where the bugs gather first.
An exterior insecticide treatment in late summer, applied by a licensed applicator according to the label, can reduce the number getting in. It works best combined with sealing, not as a replacement for it. Inside the house, a vacuum is the simplest tool, and spraying indoors does little since most bugs are hidden in walls.
What you can do yourself
- 1Caulk gaps around window frames, door trim, siding corners and utility lines in late summer.
- 2Repair or replace torn screens on windows and vents.
- 3Vacuum bugs indoors and empty the bag or canister outside right away.
- 4Drop bugs into a jar of soapy water instead of crushing them.
- 5Turn off exterior lights near entry points at night in fall.
When to call a licensed pro
- Large numbers are gathering on your home every fall.
- Bugs keep showing up in living areas through winter.
- You need gaps sealed high on the house, such as soffits and attic vents.
What stink bugs treatment costs in Michigan
$150 to $400per treatment
Typical Michigan ranges, not quotes. Price depends on the size and height of the home and whether exclusion work is included.
Typical ranges, not quotes. See the full Michigan pest control cost guide.
Stink bugs: common questions
Do stink bugs bite or harm people?
No. Brown marmorated stink bugs do not bite people or pets, do not carry disease, and do not damage homes, furniture or clothing. They are a nuisance because of their numbers and the smell they release when disturbed.
Will stink bugs lay eggs in my house?
No. They overwinter inside walls and attics but do not feed or breed there. They mate and lay eggs outdoors on plants in late spring and summer, so the numbers inside will not grow over the winter.
When is the best time to treat for stink bugs in Michigan?
Late August to mid-September, before they start moving into walls. Once they are inside, treatment options are limited and mostly come down to vacuuming. See the pest calendar for timing on other fall invaders.
Should I crush stink bugs?
Avoid it. Crushing releases a strong odor that lingers in fabric and rooms. Vacuuming or dropping them into a jar of soapy water works better. Some people keep a separate cheap vacuum just for fall invaders.