Brown Marmorated Stink Bug

Table of contents


The brown marmorated stink bug (BMSB), Halyomorpha halys (Stål), is an invasive alien insect native to Japan, Korea, Taiwan and China. It was accidently introduced to North America in the mid 1990s, and was first identified in Allentown, Pennsylvania in 2001. It has been found in most states and several Canadian provinces, though many of these are detections rather than confirmed as established in the field. Large populations exist in several Mid-Atlantic States, where BMSB is considered a significant agricultural and nuisance pest. BMSB is an excellent hitchhiker and can be moved over large distances in shipping containers, cargo and vehicles. It has been intercepted on a wide variety of trade goods coming into Ontario and other provinces from infested areas. BMSB is established in parts of southern Ontario and it is anticipated it will continue to spread.

Identifying Brown Marmorated Stink Bug


Eggs: 1.6 X 1.3 mm, barrel-shaped (like many stink bugs) and found in clusters of 20-30 on the underside of leaves; initially pale green, becoming yellow with visible red eye spots close to hatch; minute spines that form a fine line halo around the top of the egg (Figure 1) are also observed in other species.

BMSB egg mass. Red eye spots indicate the egg mass is close to hatching.

Figure 1: BMSB egg mass. Red eye spots indicate the egg mass is close to hatching.
Photo credit: Tara Gariepy, AAFC

First instar nymphs: 2.4 mm; orange abdomen with dark markings; head and legs black; remain clustered around egg mass. Note: it is difficult to distinguish this life stage from other similar-looking species (Figure 2)

First instar nymphs remain with egg mass.

Figure 2: First instar nymphs remain with egg mass.
Photo credit: David R. Lance, USDA APHIS PPQ,

Second instar nymphs: 3.7 mm; primarily black with yellowish red abdomen; single faint white band on each antennae (Figure 3).

Hatched egg mass with first instar (small red) and second instar (newly moulted red, and black) nymphs

Figure 3: Hatched egg mass with first instar (small red) and second instar (newly moulted red, and black) nymphs.
Photo credit: Gary Bernon, USDA APHIS,

Third to fifth instar nymphs: 5.5 to 12 mm; becoming darker with maturity and possessing features similar to adults including alternating light-dark pattern on edge of abdomen beginning to develop and white bands on antennae; obvious white bands on legs; pronotum has prominent spines (Figure 4); wing pads in 5th instar nymph (Figure 5).

Obvious white bands on antennae and legs on older nymphs.

Figure 4: Obvious white bands on antennae and legs on older nymphs.
Photo credit: Deepak Matadha, Rutgers University

Late instar nymph (note wing pads).

Figure 5: Late instar nymph (note wing pads).
Photo credit: Gary Bernon, USDA APHIS,


  • 14 to 17 long X 8 mm wide
  • marbled brown dorsally and pale ventrally
  • forewings have a distinct pinkish tinge when spread
  • abdominal margins extend past wings and have white inward pointing triangles alternating with dark areas
  • legs with poorly defined white band
  • smooth pronotum ("shoulders"), lacking spines except for one beside each eye
  • two white bands on antennae are diagnostic for BMSB (last antennal segment is white basally and the second last segment is white both apically and basally)

BMSB adults may be confused with rough stink bugs (Brochymena spp.) and brown stink bugs (Euschistus spp.). However, both rough and brown stink bugs lack the two white bands on the antennae and have toothed edges on the pronotum (heavily toothed in rough stink bugs) (Figure 6 A-C).

Brown marmorated stink bug (Note smooth-edged pronotum)

Figure 6A. Brown marmorated stink bug (Note smooth-edged pronotum)
Photo credit: Jennifer Read, NRCan (left) and OMAFRA (right)

Brown stink bug Euschistus servus

Figure 6B. Brown stink bug Euschistus servus
Photo credit: Antonia Guidotti, Royal Ontario Museum

Rough stink bug Brochymena quadripustulata

Figure 6C. Rough stink bug Brochymena quadripustulata
Photo credit: Steven Valley, Oregon Department of Agriculture, (left) and A. Guidotti, Royal Ontario Museum (right)


BMSB has a single generation per year in northern latitudes, though more are possible in warmer climates. Adults overwinter in human-made structures (eg. homes and woodpiles). In areas where the pest is established and where hosts are abundant, BMSB can become a major nuisance pest due to large aggregations found indoors through the fall / winter. Within the natural landscape, they overwinter in large standing dead trees. Populations tend to become established in urban areas first then spread out to nearby agricultural crops.

Adults emerge in May through June as temperatures and day length increase. Females overwinter with undeveloped ovaries and must feed for 1-2 weeks prior to mating. Once mated, females lay numerous egg masses (~ 28 eggs each) until late July or early August. Emergence from overwintering sites and egg-laying are staggered, resulting in the presence of multiple life stages throughout most of the growing season. Decreasing day length in August and September triggers movement of new adults to overwintering sites.

BMSB is well-adapted to a diversity of landscapes and does not require a specific host to facilitate establishment or spread. Patterns of dispersal between hosts during the season are not well understood and contribute to difficulties in management. The pest is highly mobile and can readily switch hosts, moving between crops throughout the growing season. Crops are at the greatest risk for injury when fruit, pods or seeds are present. Populations may build up on unmanaged woody hosts before moving into crops.


BMSB has a very broad host range that includes tree fruit, berries, grapes, vegetables, agronomic crops, ornamental trees and ornamental shrubs. Both nymphs and adults can cause injury. Damage results when nymphs and adults insert their piercing-sucking mouthparts into fruit, seedpods, buds, leaves or stems of plants. Digestive enzymes inserted into the plant result in the formation of small necrotic areas at the feeding site. Symptoms of stink bug feeding can include: discoloured, deformed, or corky fruit; abscission or collapse of berries; death of buds; leaf stippling; missing, shrivelled, or stained seeds or punctured kernels; delayed maturity (green stem syndrome in soybeans); and sap flow and discoloured bark in trees. Contamination at harvest is a concern for machine-harvested crops. Harvest of field crops may induce migration into late season crops, such as pome fruit and grapes. Crops bordering woodlots are at the highest risk of attack.


Indoors: Mechanical exclusion is the most effective way to prevent BMSB from entering structures. Seal all cracks, repair or replace damaged screens, and remove or cover window-mounted air conditioners prior to the fall. Live or dead stink bugs that have made their way indoors can be removed using a vacuum cleaner or shop vac (promptly dispose of vacuum bags or contents as the odour will persist). BMSB do not bite and they do not reproduce inside structures. The use of insecticides is not recommended.

Outdoors: While BMSB is established in urban areas, infestations have not been detected in crops in Ontario. There are several insecticides registered for use against BMSB in Canada, however action thresholds are not available for most crops. Management strategies are under development. For more information, visit the OMAFRA BMSB website

Report BMSB

A sample or high quality pictures are required for identification. Pictures of BMSB and look-alikes can be found at If you think you have found BMSB, contact the Agriculture Information Contact Centre at 1-877-424-1300 or email, and we will provide you with instructions on what to do with the sample. For the most recent map (US and Canada), as well as reports and presentations, visit

For more information:
Toll Free: 1-877-424-1300