Brown marmorated stink bug vs Western conifer seed bug
These two are easy to mix up. Here's how to tell a brown marmorated stink bug from a western conifer seed bug, and whether either one bites or stings.
Brown marmorated stink bug
Halyomorpha halys
Western conifer seed bug
Leptoglossus occidentalis
≠The key differences
Also overwinters in houses, but is shield-shaped and broader, with white bands on the antennae and along the abdominal edge, and lacks leaf-like expansions on the hind legs.
⚖︎Side by side
| Brown marmorated stink bug | Western conifer seed bug | |
|---|---|---|
| To humans | Non-venomous nuisance | Smelly secretion |
| Size | 12-20 mm long | 16-20 mm body length |
| Colours | Mottled brown, Dark brown, Pale band (antennae), Creamy white (ventral banding) | Brown, Reddish-brown, Cream, White |
| Family | Pentatomidae | Coreidae |
| Habitat | Woodlands, orchards, agricultural fields, gardens, and human structures used as overwintering sites | Conifer forests, plantations, parks and gardens with pine, spruce, fir or cedar; buildings and houses where adults overwinter |
| Range | Native to China, Japan, Korea and Taiwan; invasive and established in North America, much of Europe, parts of South America and other regions | Native to western North America; introduced and now widespread in Europe, parts of eastern North America, and East Asia |
| Active | Active spring through autumn; adults disperse and aggregate in late summer and autumn to overwinter; mostly active in daytime and at dusk | Active in spring through autumn for feeding and reproduction; adults seek shelter and are visible indoors in autumn and winter |
| Pest? | Yes | Yes |
🔍How to spot a brown marmorated stink bug
- Shield-shaped body 12-20 mm long with mottled brown 'marmorated' pattern
- Two pale bands on the antennae and alternating light/dark banding along the abdomen edge
- Pronotum with small dark punctures and faint white markings on the lateral margins
- When disturbed adults release a characteristic pungent odor
🔍How to spot a western conifer seed bug
- 16-20 mm elongated body with a distinct white or cream zigzag band across the forewings
- Leaf-like widened hind tibiae (appears as a 'leaf-foot' on the rear legs)
- Brown to reddish-brown overall color with lighter markings on the pronotum and wing edges
- When disturbed adults may emit a strong, unpleasant odor
?Frequently asked questions
What is the difference between a brown marmorated stink bug and a western conifer seed bug?
Also overwinters in houses, but is shield-shaped and broader, with white bands on the antennae and along the abdominal edge, and lacks leaf-like expansions on the hind legs.
Is a brown marmorated stink bug or a western conifer seed bug more dangerous?
Brown marmorated stink bug: Non-venomous nuisance. Western conifer seed bug: Smelly secretion. Halyomorpha halys is not venomous and does not spread human disease. They do not seek to bite people and are not venomous.
Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.