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Stink bugs vary in size and shape, but they are generally described as having shield-shaped bodies. Adult green stink bugs are usually light green. The barrel-shaped eggs change from light green to yellow and are usually found on the underside of the leaves. They can cause significant yield losses and reduce seed quality in soybean. Photo by Ivair Valmorbida, University of Missouri Extension crops entomologist. -
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Brown marmorated stink bug. U.S. Army photo.
COLUMBIA, Mo. – Something’s been stinking in Missouri soybean, corn and cotton crops since the 1990s.
University of Missouri Extension state field crops and forage entomologist Ivair Valmorbida says stink bugs feed on a variety of plant species, including corn and soybeans.
Green stink bugs make up more than 70% of the stink bugs in Missouri soybeans. The adults and nymphs use their piercing mouthparts to suck fluid from developing pods and seeds. True to their name, they give off an offensive odor when handled.
The brown marmorated stink bug is also present in Missouri crops, but it is not as abundant as the green stink bug. All overwinter as adults and emerge in the spring when temperatures and day length increase.
Stink bug feeding in soybeans reduces yield and seed quality. Seeds shrivel, shrink and become deformed and discolored. The damage generally is not apparent until harvest, when it’s too late to treat, says Valmorbida.
Valmorbida’s research team sampled 316 Missouri soybean fields in 2024 and 2025. The group found the green stink bug to be the most abundant, followed by the brown stink bug complex.
They vary in size and shape, but they are generally described as having shield-shaped bodies. Adult green stink bugs are usually light green. Eggs are barrel-shaped and change from light green to yellow. They are usually found on the underside of the leaves.
Stink bugs are most likely to appear in soybeans around mid-July to harvest. Scouting fields is your best tool in fighting stink bugs, says Valmorbida. Scout fields weekly when plants begin to bloom, and sample interior and edge areas of the fields. Bugs appear most often in rows next to weedy or wooded areas.
MU’s Pest Monitoring Network offers free text alerts to notify farmers when insects are active in specific locations. To sign up on the MU Integrated Pest Management website or email Valmorbida at ivairvalmorbida@missouri.edu.
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Green stink bug. Stink bugs vary in size and shape, but they are generally described as having shield-shaped bodies. Adult green stink bugs are usually light green. The barrel-shaped eggs change from light green to yellow and are usually found on the underside of the leaves. They can cause significant yield losses and reduce seed quality in soybean. Photo by Ivair Valmorbida, University of Missouri Extension crops entomologist.
Brown marmorated stink bug. Brown marmorated stink bug. Credit: U.S. Army.
