Iowa Pest GuideSourced pest help for Iowa homes

Brown Marmorated Stink Bugs in Iowa Homes

Updated · By Kasey, Waukee, Iowa

If a brownish, shield-shaped bug just buzzed past a lamp in your Urbandale living room, you may have met the brown marmorated stink bug. Homeowners in Johnston, Clive, Waukee and across Iowa find them on walls and windows in fall, and sometimes all winter long.

Iowa State University (ISU) Extension calls it an invasive insect that is, in Iowa, reported primarily as a household nuisance. This guide covers how to identify it, why it comes inside, what you can do yourself and when it makes sense to call a licensed pest professional.

What it is and how to identify it

ISU describes the brown marmorated stink bug (often shortened to BMSB) as having a roughly triangular, "shield" shaped body. Adults are about 5/8 inch long and mottled brownish-grey. "Marmorated" means marbled, which describes the mottled color on its back.

ISU's tips for telling it apart from other stink bugs:

Look-alikes. ISU's comparison page lists a few common Iowa insects that get mistaken for it:

If you still are not sure, the ISU Plant and Insect Diagnostic Clinic identifies insects for Iowans. Check its website for current instructions on sending a sample or photos, and for any fees.

How it got to Iowa

ISU says the bug is native to China, Japan, Korea and Taiwan and was first identified in the U.S. in 2001 in Allentown, Pennsylvania, possibly arriving in shipping containers. In Iowa, a single dead specimen was collected in Cedar Rapids in February 2011. Since then ISU says it has been reported from over one-third of Iowa's counties, and it travels readily with people and shipping.

ISU still tracks where it shows up. If you find one in a county where it has not been recorded, ISU asks Iowans to email photos to insects@iastate.edu.

Is it harmful?

ISU is reassuring here. Stink bugs:

The problem is mostly annoyance. ISU notes they are large, can show up in large numbers and fly, and like all stink bugs they give off a disagreeable odor. ISU describes the brown marmorated stink bug's odor as cilantro-like. If you have health concerns about insects in your home, talk with a healthcare provider.

What about gardens? ISU says this bug feeds on sap from many plants, and it has damaged crops and fruit in the mid-Atlantic states. In Iowa, ISU reports that damage to field crops, fruits, vegetables or ornamentals has not been reported to date.

Why it shows up (season and local angle)

ISU explains the yearly cycle like this:

ISU points out that they are not seeking warmth and cannot predict cold or know a house will be heated. Every stink bug you find indoors walked or crawled in through a crack or gap in the fall, even if you first see it in January. Common entry points ISU lists are gaps around windows and doors, between the foundation and siding, between the siding and soffit, and around chimneys.

That is the same pattern as Asian lady beetles and boxelder bugs, which often arrive at the same time. See our Asian lady beetle guide and boxelder bug guide.

What you can do yourself

Seal entry points first

ISU says the first step is to seal cracks, gaps and potential entry points before they get in. Its suggestions:

ISU is realistic that pest-proofing will never be perfect, but it is the preferred approach. The same work helps keep out fall mice. See our guide to mice in Iowa homes this fall.

Bugs already inside: vacuum, then empty it

ISU says stink bugs already indoors should be vacuumed or swept up and discarded. If you use a vacuum or shop vacuum, remove and discard the bag promptly so the smell does not linger.

ISU says indoor insecticide sprays are not recommended for this bug. Spraying indoors, including "bug bombs," does not prevent entry and only affects bugs out in the open at the time.

Outdoor sprays: a supplement, not the main fix

ISU's general advice for fall accidental invaders is that residual insecticide sprays can supplement pest-proofing, applied by the homeowner or a professional. Key points from ISU:

Always read and follow the pesticide label. The U.S. EPA notes that every pesticide label says it is a violation of federal law to use the product in a manner inconsistent with its labeling. We do not recommend specific brands.

When to call a licensed pro

A professional can make sense when:

How to choose a licensed Iowa applicator

Under Iowa's administrative rules, anyone in the business of applying pesticides to another person's property must be licensed and certified by the state. Household pest work is Category 7A, General and Household Pest Control. Before you hire:

  1. Ask for the company's Iowa license and the technician's certification.
  2. Verify both in the Iowa Department of Agriculture and Land Stewardship lookup.
  3. Ask whether the plan includes sealing entry points, not only spraying, and when they plan to treat.

See our guide to choosing a pest pro for more questions to ask.

Local pest pros in the Des Moines metro

See all 77 listed companies by town →

Listings are informational, not endorsements or rankings, and no company paid to be listed. Details come from each company’s own website. Always verify an Iowa pesticide license with IDALS before hiring. Companies can request a correction or removal.

Is your business missing or wrong? Contact us with your website and the towns you serve.

Frequently asked questions

Do brown marmorated stink bugs bite?

No. ISU Extension says they do not bite, cannot sting and do not feed on people, pets, the house or its contents.

Will stink bugs lay eggs in my house?

No. ISU says they do not feed or reproduce indoors, and females cannot reproduce until early spring. Bugs you see in winter came in during the fall.

Why am I seeing stink bugs in January?

ISU says every stink bug found indoors crawled in through cracks and gaps in the fall, usually late September to October. They spend the winter hidden in walls and other protected spots, and some wander out into living areas.

Should I squash them?

Stink bugs are named for the odor they give off, and ISU describes this one's as cilantro-like. ISU recommends vacuuming or sweeping them up instead, and promptly removing the vacuum bag.

Do they damage Iowa gardens?

They feed on plant sap and have damaged crops in the mid-Atlantic states, but ISU says damage to field crops, fruits, vegetables or ornamentals has not been reported in Iowa to date.

Nearby towns we cover

Related guides

Sources

  1. Brown Marmorated Stink Bug - Iowa State University Extension and Outreach (checked 2026-10-23)
  2. Stink Bugs and Similar-Appearing Insects in Iowa - Iowa State University Extension and Outreach (checked 2026-10-23)
  3. It is Accidental Invader Season Again - Iowa State University Extension and Outreach (checked 2026-10-23)
  4. Fall Nuisance Invaders Are On the Move - Iowa State University Extension and Outreach (checked 2026-10-23)
  5. Submitting an insect for identification - ISU Plant and Insect Diagnostic Clinic (checked 2026-10-23)
  6. Introduction to Pesticide Labels - U.S. EPA (checked 2026-10-23)
  7. Iowa Admin. Code r. 21-45.22, License and certification standards for pesticide applicators (checked 2026-10-23)
  8. Pesticide applicator and company license lookup - Iowa Department of Agriculture and Land Stewardship (checked 2026-10-23)

We link to the original sources so you can read them yourself. Product names are not endorsements.