No. 3 Article 1/April 22, 2011

Brown Marmorated Stink Bug Found in Illinois

The brown marmorated stink bug (BMSB) has been making headlines in Illinois the past couple of weeks. Since the first confirmation of this invasive insect in Cook County in the fall of 2010, additional reports have continued in 2011. In January, a homeowner in Kane County reported an infestation, and just a couple of weeks ago, homeowners in Normal (McLean County) and Urbana (Champaign County) each submitted a single specimen for identification. Reports continue to circulate in northeastern Illinois.

Why is BMSB important? Like many invasive species, BMSB has a long list of host plants, including many woody ornamental trees as well as several agricultural crops, including fruit trees, grapes, tomatoes, corn, and soybeans. Also like many invasive insects, the BMSB is easily moved from location to location by humans (hitchhiking on vehicles, through movement of shipping materials and plants). In addition to feeding on plants, BMSB is considered a nuisance pest to homeowners. Much like boxelder bugs or multicolored Asian lady beetles, these stink bugs congregate on houses in late fall and move indoors. Homeowners are likely to first spot new infestations, as BMSBs will initially feed on common landscape ornamentals.

How can I tell the difference between BMSB and other stink bugs found in Illinois? Adult BMSBs (see this identification poster [Adobe PDF]) have the typical shield-shaped body of all stink bugs. As their name indicates, they have a marmorated, or mottled, brown color. Their antennae have distinct white bands; on the edge of the abdomen they have alternating black and white bands. The underside of the abdomen is white, and the legs may also have faint white banding.

Adult brown marmorated stink bug. (Photo courtesy Michael Jeffords.)

When should I expect to see BMSBs? Typically adult BMSBs begin to move to overwintering locations in September, with peak movement in late September and early October. Homeowners may start to see them begin to gather on homes, barns, and garages during this time. In the spring, adults emerge from their overwinter locations as temperatures begin to warm. After mating, eggs are laid on the undersides of leaves from June to August, with hatch occurring 3 to 7 days later. Nymphs pass through 5 instars (each instar stage lasting about a week). New adults begin to appear in late July or August.

What kind of injury does BMSB cause? Unlike many insect pests that attack plants only during certain times of the growing season, BMSBs feed on host plants all season long. This is cause for great concern in fruit crops, where they begin feeding early in the season and continue through harvest. Growers should monitor fruit for sunken areas where the insect has fed. These places will be discolored, and corky areas will be present under the skin of the fruit. In corn and soybean, BMSBs feed on developing pods or corn ears. They can feed through the husks and pods with their sucking mouthparts, causing shriveled kernels or beans. In tomatoes and peppers, feeding also results in corky areas and discoloration.

Damage caused by BMSB to apple. (Photo courtesy Maryland Department of Agriculture.)

From left: Brown marmorated stink bug on outside ear, kernel damage, and tomato damage. (Photos courtesy Virginia Cooperative Extension. David Wright, corn photos; Eric Day, tomato.)

What should I do if I think the BMSB is in my home or on my property? We are very interested in where these insects may be and continue to try to determine their distribution in Illinois. If you have a suspect specimen, we would like to see it. To positively confirm any insect as a BMSB, we need to look at it. Suspect stink bugs may be sent to Kelly Estes, 1816 S. Oak St., Champaign, IL 61820. Please put stink bugs in a crush-proof container (a pill bottle, a check box, etc.). You can also send a photo to for preliminary screening if you wish.--Kelly Estes, Illinois Natural History Survey

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