Brown Marmorated Stink Bug

Published   5/20

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You can help stop a new pest by recognizing and reporting it.

The invasive brown marmorated stink bug (BMSB), Halyomorpha halys, has been found in numerous locations in California. Wherever BMSB takes up residence, it can cause severe crop and garden losses and become a nuisance in and around homes and other buildings. The ability of BMSB to hitchhike in vehicles and planes has allowed it to spread rapidly to new areas. Since it was introduced to the United States from Asia in the 1990s, BMSB has become established in the mid-Atlantic states as well as states along the Pacific.

How to Identify BMSB

Brown marmorated stink bug eggs and nymphs
enlarged egg
  • EGGS: Laid in clusters of 20-30 on underside of leaves, barrel-shaped, white to pale green
  • YOUNG NYMPHS: Abdomen orange with brown markings
brown marmorated stink bug distinguishing characteristics

Similar Stink Bugs

(also known as shield bugs)

BMSB adults look similar to other brown stink bugs. Here are some tips for telling adults apart.

red-shouldered stink but

RED SHOULDERED STINK BUG: Edge of abdomen concealed; antennal bands, if present, are not white; less than 1/2 inch long

rough stink bug

ROUGH STINK BUG: Distinctive teeth jutting out from shoulder; no antenna bands; 2/3 inch long

consperse stink bub

CONSPERSE STINK BUG: Legs dotted with dark spots; no antenna bands 1/2 inch long

Impact of BMSB on Crops and People

CROP DAMAGE: BMSB may reach very high numbers, and since one bug can feed on many fruit, losses can be severe. Adults and nymphs suck juices from fruit and seeds, creating pockmarks and distortions that make fruit and vegetables unmarketable. Damaged flesh under the skin turns hard and pithy. BMSB damages fruits (e.g., apple, pear, citrus, stone fruits, and fig), berries, grapes, legumes, vegetables, and shade trees.

damage produced by stink bugs on tomato
damage produced by stink bugs on peach
damage produced by stink bugs on pear
BMSB damage to tomato (left), peach (center), and pear (right)

NUISANCE TO PEOPLE: BMSB seeks winter shelter, and large numbers may congregate on outside walls or invade homes by entering through small openings. It is also a pest in home gardens. These insects stink when disturbed.

How it Spreads

BMSB travels long distances by hitching rides in vehicles or as stowaways when furniture or other articles are moved, often during winter months. As a result, most new infestations are found in urban areas.

Report any Sightings

If you find a stink bug that you suspect might be a BMSB, place it in a container and carefully note where and when you collected it. Take the sealed container to your county agricultural commissioner or local UC Cooperative Extension office.

More information

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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