Watch Out for the Stinking Stink Bug : Brown Marmorated Stink Bug

Watch Out for the Stinking Stink Bug : Brown Marmorated Stink Bug

Known scientifically as the Halymorpha halys, the brown marmorated stink bug (BMSB) is an invasive exotic pest found in parts of Asia such as China, Japan, Korea, and Taiwan. Although an unconfirmed sighting in Pennsylvania in 1996 of BMSB was reported, the first confirmed sighting occurred in the United States in 2001.


In 2014, reproducing BSMB populations were found in California, Connecticut, Delaware, Florida, Indiana, Kentucky, Maine, Maryland, Massachusetts, Mississippi, Missouri, New Hampshire, New Jersey, New York, North Carolina, Ohio, Oregon, Rhode Island, South Carolina, Tennessee, Virginia, Washington, D.C., and West Virginia.

There have also been reports of BMSB in the following states: Alabama; Arizona; Georgia; Illinois; Iowa; Michigan; Minnesota; Nebraska; Washington; Wisconsin. Since its discovery in 2010, BMSB has been confirmed to exist in the following counties in Wisconsin: Brown, Dane, Jefferson, Kenosha, Manitowoc, Racine, and Waukesha. There have been no confirmed cases of BMSB eggs in Wisconsin to date. It’s possible that a breeding population exists in Wisconsin, but only one immature BMSB (nymph) was discovered in Dane County in October 2012.


BMSB adults resemble native stink bugs in terms of size, shape, and appearance. Their body length ranges from one-and-a-half to five-and-a-half inches, and they are a mottled brown to grey colour with brown spots. One of the most distinguishing features of an adult BMSB is its abdominum, which has alternating light and dark brown spots (see the white arrow in the photo above). The tips of their antennae alternate between light and brown bands.

Adult brown marmorated stink bug. (Photo courtesy of David R. Lance, USDA APHIS PPQ,

The pupils of their eyes are a deep wine colour. Squash bugs and leaf-footed bugs, for example, may look like BMSBs, but they don’t have the distinctive shield-shaped body that stink bugs have.

BMSB nymphs are much smaller than adults, ranging in size from a pinhead to about a half-inch. Nymphs have oval faces and dark red eyes, just like adults. The colour of nymphs varies with age. They start out yellow-red, but as they get older, they turn creamy white with reddish spots. On the undersides of leaves, BMSB eggs are light green to yellow and barrel-shaped.

Symptoms and Effects

Depending on the plant host, symptoms of BMSB damage will vary. A surface blemish known as “cat-facing” is caused by early-season feeding on developing apples. This makes the fruit unsellable. Feeding apples later in the season results in water-soaked or necrotic (dead) areas, which increase the fruit’s susceptibility to rot organism invasion.

Symptoms of late-season feeding may not appear for four to five weeks after the fruit has been placed in cold storage, due to this unfortunate circumstance. In other small fruit crops, BMSB damage is similar to that in apples, but fruit drop is possible as well.


Currently, there are no biological controls available in the United States for BMSB, a non-native insect. Many insecticide labels are still not BMSB-compliant at this time. BMSB is unlikely to be effectively controlled with low-risk/narrow-spectrum insecticides. Insecticides with a broad spectrum of activity (e.g., organophosphates, carbamates, and neonicotinoids) are more likely to be effective against this particular insect pest.

Once the restricted entry interval for the insecticide has passed, confirm the efficacy of sprays by evaluating BMSB numbers only if you decide to use an insecticide for BMSB control. PRODUCTS THAT DO NOT DECREASE BSMB COUNTS SHOULD NOT BE REUSED.

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