I should be a large image.

Brown Marmorated Stink Bug

Halyomorpha halys

Updated Apr 20, 2026

Make a Positive Identification

Brown marmorated stink bugs are marbled brown, shield-shaped bugs about 5/8 inches long. They may congregate in large numbers on the warm sides of buildings. They are a major crop and fruit pest, and damage many ornamental plants.

Species: Brown marmorated stink bug

Steven Valley, Oregon Department of Agriculture, Bugwood.org

Adults are about 5/8 inch long, and marbled brown. Identifying features are:

Distinct white bands on the dark antennae.
Smooth margin on the front edge of the “shoulders”.
White bands on sides of the wings.
White bands on legs.
They emit a strong cilantro-like smell when disturbed or crushed.

Species: Brown marmorated stink bug

David R. Lance, USDA APHIS PPQ, Bugwood.org

Immature BMSB (nymphs) molt five times as they mature into adults. Each molting is called an “instar”. Instar #1 (newly hatched) is black with yellowish red markings on the abdomen.

Two generations per season can occur in Oregon.

Species: Brown marmorated stink bug

David R. Lance, USDA APHIS PPQ, Bugwood.org

Nymphs grow larger with each instar. Older instars have rectangular spots on the back of the abdomen.
All instars have a spiny margin on the front edge of the “shoulders”.

Species: Brown marmorated stink bug

Susan Ellis, Bugwood.org

Eggs are laid in clusters ranging in number from 25-30 eggs. They are barrel shaped, and white to pale green. Short spines encircle the top. They are attached to the underside of leaves.

Species: BMS damage

Sylvia Rondon, Oregon State University

Brown Marmorated Stink Bug damage

Adults and nymphs inject tissue-destroying enzymes and suck juices from fruit and seeds. They create pockmarks and distortions that make fruit and vegetables unmarketable. Damaged flesh under the skin turns hard and pithy.

Free help Identifying Weeds, Insects & Pests

Get expert pest management info & advice online from OSU's Ask Extension.

Get Help

LOOK-ALIKES: SIMILAR STINK BUGS

Species: Rough stink bug

Steven Valley, Oregon Department of Agriculture, Bugwood.org

Rough stink bug, Brochymena sulcata, Differences from BMSB:

No white bands on the antennae.
Toothed (rough), rather than smooth, shoulder margin.
Front of head has two points.

Species: Consperse stink bug

Steven Valley, Oregon Department of Agriculture, Bugwood.org

Consperse stink bug, Euschistus conspersus, Differences from BMSB:

No white bands on the antennae.
Finely toothed margin on front edge of shoulder.
Legs have distinct dark spots rather than white bands.
A little smaller, about 1/2 inch long.

Species: Shield bug

Hanna Royals, Museum Collections: Heteroptera, USDA APHIS PPQ, Bugwood.org

Shield bug, Holcostethus sp, Differences from BMSB:

No white bands on the antennae.
No white bands on legs.
No white bands along edge of abdomen.

Brown Marmorated Stink Bug Benefits

Brown marmorated stink bugs are food for other species of insects, spiders, and some birds and mammals.

Brown Marmorated Stink Bug Risks

Brown marmorated stink bugs are a serious pest of many fruit and fruiting vegetable crops.
They migrate into dwellings in the winter.
Their excrement may leave spots on curtains, furnishings, and clothing.
When crushed, they give off an offensive odor.

Risk Card

Does it cause harm?

Adults & Children

None

Property

Low

Pets

None

Annoyance

Some

Environment

None

Action Depends on Context

NEED HELP?

Consider a licensed pest control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon and other states can suggest other methods.

SEE OTHER COMMON PACIFIC NORTHWEST INSECTS

Content provided by editor Chris Hedstrom and writer Signe Danler. Pesticide safety information edited by Kaci Buhl.

Chris Hedstrom

Signe Danler (Editor/Writer)

Signe Danler is a veteran Master Gardener and landscape designer, with an MAg degree in Horticulture from OSU, and an emphasis on Urban Horticulture. As instructor for the OSU Extension Service online Home Horticulture and Master Gardener Program, she uses her experience and training in gardening, urban forestry and ecological landscaping to communicate about and promote sustainable gardening and landscaping practices.

Kaci Buhl

At the state level, I lead the Pesticide Safety Education Program (PSEP). The program hosts live recertification events around the state, serving over 1,000 licensed pesticide applicators each year. We also produce web-based training modules and license-preparation study manuals. Special training for unlicensed pesticide applicators is also available through a grant from the USDA Specialty Crop Block Grant Program. The PSEP at OSU works closely with the Oregon Department of Agriculture's Pesticides Division.