Invasive insect

Brown marmorated stink bug

Halyomorpha halys

Brown marmorated stink bug identification: a shield-shaped, mottled brown bug with banded antennae that crowds into houses each fall.

By WildScope Editorial Desk

Published November 3, 2026 Last reviewed November 3, 2026

Brown marmorated stink bug (Halyomorpha halys) — Photo: David R. Lance, USDA APHIS PPQ · CC BY · source

Brown marmorated stink bug (Halyomorpha halys), photo 2 — Photo: Gary Bernon, USDA APHIS · CC BY · source

Brown marmorated stink bug (Halyomorpha halys), photo 3 — Photo: Joltthecoat · CC BY-SA · source

A brown marmorated stink bug is about 5/8 inch long, shield-shaped and mottled brown. The two checks that settle it are the alternating light and dark bands on the last two antennal segments and the matching light and dark banding along the exposed edge of the abdomen. Native brown stink bugs are smaller, duller and lack those bands.

The bug has two separate lives in a homeowner’s year. From late April through summer it feeds on fruit, vegetables and ornamentals, piercing the tissue and leaving pitted, dimpled or spongy spots. On apples the damage is called cat facing, and it makes the fruit unmarketable. From September it switches to finding shelter, gathering on warm walls and slipping through cracks around windows, doors, siding and utility pipes. It does not bite or sting people or pets, does not spread disease and does not eat or bore into wood. It is a nuisance indoors, not a structural pest.

What works is exclusion, done before the bugs start gathering. Caulk and weatherstrip the gaps, repair screens and remove window air conditioners. Inside, vacuum or sweep them into soapy water rather than crushing them. Extension services advise against indoor sprays, foggers and wall-void treatments, and say exterior sprays do not stop the invasion. Our prevention guide covers the sealing checklist, and the removal guide covers what to do once they are inside. If you are trying to name the bug on the curtain, the stink bug vs boxelder bug comparison puts the two side by side. More insect profiles are on the insects hub, and photo credits and licences sit on the image credits page.

Identification

Look for the combination of characters below. A single feature is rarely enough, especially when a native look-alike is present.

Adult size and shape: About 17 mm (0.66 inch) long and almost as wide as it is long, with the shield shape typical of stink bugs. The upper and lower body are shades of brown.
Antennae and wing tips: The last two antennal segments have alternating light and dark bands. The thin, overlapping tips of the front wings also show darker banding, which is one of the most reliable checks.
Body surface: Patches of coppery or bluish metallic punctures, which are small rounded depressions, sit on the head and the shield behind it.
Nymphs: There are five wingless stages, from about 2.4 mm to 12 mm long. The eyes are deep red, and the abdomen shifts from yellowish red to off-white with reddish spots.
Eggs: Light yellow to yellow-red, barrel-shaped and about 1.6 by 1.3 mm, attached side by side in masses of 20 to 30 on the undersides of leaves.
Season: Adults emerge from overwintering sites from late April to mid-May and lay eggs from May through August. They begin searching for winter shelter in September and October.

Look-alikes

Native brown stink bug

Euschistus servus

Native brown stink bugs are dull brownish-yellow and about 1/2 inch long. Their antennae lack the bold light bands, and the wing tips lack the dark banding of the brown marmorated stink bug.
Boxelder bug

Boisea trivittata

Boxelder bugs are oval, about 1/2 inch long, and dull black with red-orange along the edges of the front wings. The nymphs are red and black, unlike the mottled brown stink bug nymphs.
Spined soldier bug

Podisus maculiventris

The spined soldier bug has pointed shoulders behind the head and a dark line at the tip of each forewing that forms one streak when the wings overlap. It is a predator, not a plant feeder.

Range and status

Native range: East Asia

Regulatory status by state

No state regulatory classification has been verified for this species yet. Check the current noxious-weed list for your state before making a regulatory decision.

Why it matters

Brown marmorated stink bug feeds on a long list of fruits, vegetables and ornamentals. Feeding on apples causes a distortion called cat facing that makes the fruit unmarketable, and feeding on tomatoes and peppers leaves spongy, discolored tissue. In fall the bug gathers on warm, elevated surfaces and squeezes into houses to overwinter, sometimes in large numbers.

Management

Seal the outside before fall

Timing: Late summer, before bugs begin gathering in September and October.

Find the gaps first, then seal cracks around windows, doors, siding, utility pipes and chimneys with good-quality silicone or silicone-latex caulk. Repair damaged screens, add weather stripping and remove window air conditioners. Exclusion is the best method for keeping the next invasion out.

Vacuum or sweep, do not crush

A dry or wet vacuum collects them quickly, though the canister may smell for a while. You can also sweep them into a container of soapy water. Crushing them releases the odor that gives stink bugs their name.

Skip indoor sprays

University of Maryland Extension says pesticides are generally ineffective and not recommended inside the home. Foggers do not kill all the bugs or stop more from entering, and spraying wall voids can leave dead insects for carpet beetles to feed on.

Treat exterior spraying as a stopgap

Exterior insecticide applications may give minor relief where sealing is impossible, but they do not stop the invasion, and residue breaks down in sunlight within days to a week. Extension services generally do not recommend them. Follow the product label; the label is the law.

Sources

Facts on this page were checked against the sources below. Each link shows the date the source was accessed.

Brown Marmorated Stink Bug — National Invasive Species Information Center Accessed November 3, 2026
Brown Marmorated Stink Bug — Penn State Extension Accessed November 3, 2026
Tips for Dealing With Brown Marmorated Stink Bugs — University of Maryland Extension Accessed November 3, 2026
Brown Marmorated Stink Bug - Frequently Asked Questions — University of Maryland Extension Accessed November 3, 2026
Common Stink Bugs of the Mid-Atlantic — University of Maryland Extension Accessed November 3, 2026
Boxelder Bugs — University of Maryland Extension Accessed November 3, 2026

Stink Bug vs Boxelder Bug: Which Is in Your House?
Stink bug vs boxelder bug: boxelder bugs have red-orange stripes; brown marmorated stink bugs are mottled brown with banded antennae. Both come inside in fall.
Stink Bug vs Kissing Bug: Which One Bites?
Stink bug vs kissing bug: stink bugs are shield-shaped plant feeders that do not bite. Kissing bugs have a cone-shaped head and can carry Chagas disease.