What’s That Bug: Brown Marmorated Stink Bug

Posted by: Jessica Wong, Master Gardener Coordinator, Broomfield County Extension

When people find out that I’m an entomologist they sometimes ask one of two questions: “So you study where words come from?” Or they pull out their phones to show me a blurry photo and ask, “What’s that bug?” I can’t tell you the origin of the word ‘bug’, but I can tell you a little bit about bug biology.

The latest blurry photo shared with me was of a brown marmorated stink bug (BMSB), Halyomorpha halys, inside a house. This insect is originally from Asia and it was accidentally brought to the mid-Atlantic in the late 1990s. Since then BMSB have spread to other parts of North America where they are nuisances and pests to homeowners, gardeners, and farmers.

Map of brown marmorated stink bug distribution from stopbmsb.org

There are a number of stink bug species found in Colorado, but BMSB can be identified by a few key characteristics. The adults are about 0.5 to 0.6-inch long and are brown mottled with black and tan. Their antennae have black and white bands, and the sides of their abdomens also have an alternating black and white pattern.

Key characteristics of BMSB from ipm.msu.edu/invasive_species/brown_marmorated_stink_bug

These bugs are common home invaders in the fall and winter, and in the spring and summer they can be pests of a large variety of plant species. Their hosts range from ornamentals such as tree of heaven and eastern redbud to crops including beans, tomatoes and apples. Feeding of BMSB on crops can result in fruit deformities and internal damage that compromise quality.

BMSB feeding on raspberries from stopbmsb.org by Cesar Rodriguez-Saona and Doug Pfeiffer

Necrotic spots on an apple from stopbmsb.org by Tracy Leskey and Torri Hancock

For now BMSB are not a serious problem in Colorado, but having seen the damage they cause in other parts of the country I plan to keep a watchful eye out for this one. If you want to learn more about BMSB you can visit the StopBMSB website. You can also report a sighting on the StopBMSB website if you find one.

One final thought in case you’re curious about what brown marmorated stink bugs smell like: they kind of smell like cilantro, so I guess they stink if you aren’t a fan of cilantro.