The brown marmorated stink bug, Halyomorpha halys, is the most recent invasive agronomic insect found in Illinois. First identified in 1998 near Allentown, Pennsylvania, this stink bug has slowly dispersed across the United States. It is currently found in 33 states, including every state east of the Mississippi River and as far west as California,Washington, and Oregon. Over the past months, we have confirmed its presence in four Illinois counties (Cook, Kane, Champaign, and McLean). The native range for this damaging pest is China, Japan, Korea, and Taiwan.
Adult brown marmorated stink bugs are roughly two-thirds of an inch long and shield-shaped, making them similar to other more familiar stink bugs in Illinois, including the green (Acrosternum hilare) and brown (Euschistus servus) stink bug species. Red eyes, white stripes on the antennae, and black and white bands along the margins of the front pair of wings help to distinguish brown marmorated stink bugs. Nymphs (immature stink bugs) emerge from elliptical eggs that are light yellow to yellowish-red and most often found on the lower surfaces of leaves in masses, each mass containing 20 to 30 eggs. Immature stink bugs go through five nymphal instars prior to reaching the adult stage. During the spring, adults break their dormancy and mate, and the females begin laying eggs, continuing throughout summer. A single generation per year is expected for most of Illinois. Some areas of southern Illinois could experience a second generation.
Like many invasive insects, brown marmorated stink bugs will feed on a very long list of host plants. In addition to several woody ornamental trees, they feed on many crops grown in Illinois - peaches, apples, grapes, soybeans, corn, tomatoes, peppers, and more. They are also considered a nuisance pest to homeowners. Much like boxelder bugs or multicolored Asian lady beetles, brown marmorated stink bugs congregate on houses in late fall and move indoors to overwinter. New infestations are most likely to be spotted by homeowners, as the insects initially feed on common landscape ornamentals. The brown marmorated stink bug is not to be taken lightly. Unlike many insect pests that attack plants only during certain times in the growing season, it feeds all season long. Populations in the mid- Atlantic states have grown tremendously over the past several years. The brown marmorated stink bug has become a serious pest of fruit, vegetable, and agronomic crops in that area and will likely come to threaten these commodities in additional parts of the United States.
Soybean producers are encouraged to be vigilant in their scouting efforts this season for both brown marmorated stink bug and other stink bug species. In the past few years, the redbanded stink bug (Piezodorus guildinii Westwood) and the redshouldered stink bug (Thyanta custator Fabricius) have become more problematic in soybean fields across many areas of the southeastern United States. The redbanded stink bug has been found in several states, including Arkansas, Louisiana, Mississippi, Missouri, and Tennessee. In Louisiana, economic infestations have been reported, and management challenges have become significant. Thus far, redshouldered stink bugs have been easier to manage. The suggested economic threshold for redbanded stink bug is 24 insects per 100 sweeps.
Differentiating the redbanded and redshouldered stink bugs requires careful examination of the ventral (bottom) surface of the insect. Redbanded stink bugs possess a spine between the third pair of legs that is directed toward the head. To date, there has been no official confirmation of either species in Illinois. However, last summer, a U of I staff member photographed a stink bug species that closely resembles these near the South Farms. This prompted justifiable concern, and producers should be wary of potential future infestations.
Of greatest concern to soybean producers is the potential damage to developing seeds inside immature pods. Brown marmorated stink bugs can also injure tender kernels of corn by penetrating corn husks with their piercing and sucking mouthparts. U of I entomologists will survey soybean fields throughout Illinois this season; results will be shared with producers in fall and winter Extension meetings. This survey effort has received generous financial support from the Illinois Soybean Association.
Kelly A. Estes
State Survey Coordinator, IL Cooperative Agricultural Pest Survey Program
Michael E. Gray
Professor of Crop Sciences
ANR Extension Assistant Dean