Pest profile

Rough Stink Bugs

Brochymena species · Hemiptera: Pentatomidae[3]

Rough stink bugs are often mistaken for brown marmorated stink bugs, but they're partly predatory and cause no significant plant damage.[1][2]

Rough stink bug seen from above, a mottled gray shield-shaped bug with toothed edges on the shoulders, on a hand
Rough stink bug seen from above, a mottled gray shield-shaped bug with toothed edges on the shoulders, on a hand. (c) Bill Keim, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adults are broad, flattened, shield-shaped bugs about 7/16 inch to nearly 7/8 inch long.[1][2]
  • They're mottled gray or brownish with black and white, which blends in with tree bark.[1][2]
  • The front edge of the thorax, the shoulders, is rough or toothed, which gives the group its name.[1]
  • Eggs are barrel shaped and pearly white, laid in clusters of about 10 to 20.[1][2]

Look-alikes

Look-alikeHow to tell them apart
Brown marmorated stink bugRough stink bugs have two white bands on each hind leg, unbanded antennae, a pointed face and toothed shoulders. The BMSB has one hind-leg band, banded antennae, a blunt face and smooth shoulders.[1]

Where it lives

They're most common in trees and shrubs. California has at least six Brochymena species, and in Colorado Brochymena sulcata is found statewide.[1][2]

US map: public records from 46 states since 1990 (GBIF).

Biology and life cycle

Eggs hatch in about one to two weeks, and young nymphs stay together beside their empty egg shells at first.[1][2]

Adults live two to three months; where winters are cold they overwinter as adults under loose bark or in buildings.[1][2]

Colorado populations have one generation a year, with new adults appearing in August.[2]

Damage and signs

  • They eat caterpillars, leaf beetle and sawfly larvae and other slow, soft-bodied insects.[1][2]
  • They also feed on leaves, seeds and shoots of trees such as ash, walnut, willow and boxelder, without significant injury.[2][1]

Health risk

Neither source mentions bites or other harm to people. They're mostly noticed when they wander indoors in fall or arrive on firewood.[2][1]

Control

Prevention

No treatment is needed outdoors; they cause no significant plant injury and eat some pest larvae.[2][1]

Keep them out

Expect a few indoors in fall, when they look for winter shelter, and check firewood before bringing it in.[2]

Biological control

Controlling ants and avoiding persistent, broad-spectrum sprays protects them along with other natural enemies.[1]

Common questions

Is this a brown marmorated stink bug?
Check the shoulders and antennae: toothed shoulders and unbanded antennae mean a rough stink bug.[1]
Why is a rough stink bug in my house?
Adults look for winter shelter in fall and sometimes come in on firewood.[2]
Do rough stink bugs damage trees?
They feed on tree leaves and seeds but aren't linked to significant injury.[2]

Sources

  1. University of California Statewide IPM Program, “Rough Stink Bugs (Natural Enemies Gallery).” ipm.ucanr.edu/natural-enemies/rough-stink-bugs/ (accessed 2026-10-06)
  2. Colorado State University Extension, “Colorado Insect of Interest: Rough Stink Bugs.” webdoc.agsci.colostate.edu/bspm/Hexapoda%20(Insects)/Rough%20Stink%20Bugs.pdf (accessed 2026-10-06)
  3. iNaturalist, “Brochymena taxon page (order and family).” www.inaturalist.org/taxa/127347 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.