Stink bug appearance delayed in 2025 Western Kentucky soybeans
Stink bug appearance delayed in 2025 Western Kentucky soybeans
We have observed significant numbers of stink bugs over the past few days in some soybean fields in western Kentucky. Their arrival appears later than in previous years, likely due to the rainy spring delaying planting this season. In the 2024 season, green stink bug (GSB) (Chinavia hilaris) and Brown marmorated stink bug (BMSB) (Halyomorpha halys) were the most abundant species found in soybeans in western Kentucky. In 2025, GSB remains the most common, while the BMSB has -so far- been observed in very low numbers compared to GSB.
Although pressure has developed later this year compared to previous seasons, stink bugs are now present at levels that may require management in some areas. We have recorded average numbers ranging from 0.3 up to 4.3 stink bugs per 10 sweeps in fields sampled before R6. This means that we are finding some full-season fields where treatment thresholds are reached, and the expectation is that pressure will increase in double-crop soybeans as the season progresses.
Stink Bugs Description and Management
Stink bugs can be recognized by their distinctive shield-shaped body. Two of the most common species most frequently encountered in Kentucky soybeans are GSB, BMSB and a species complex on brown stink bugs, including the brown stink bug (Euschistus servus) (Figure 1).
Green stink bug adults are uniformly light green, 0.55–0.75 inches long. Early instar nymphs are black with orange markings and distinct white spots on the abdomen, becoming green with black/orange patterning in later instars. Brown marmorated stink bug adults are around 0.5–0.7 inches long. Both adults and nymphs are marbled brown with whitish bands on antennae, legs and abdomen edges. The brown stink bug E. servus adults are about 0.4–0.6 inches long brownish, with darker antenna and rounded shoulders. Nymphs are pale and oval to shield shaped as they develop.
Economic thresholds are typically reached at an average around 2-4 stink bugs per 10 sweeps (nymphs + adults) between the R3 and R6 stages. If populations exceed these thresholds, insecticide applications may be required. Contact the local Extension agent for guidance on insecticide selection and application timing.
Take-home message
Many full-season soybean fields are already at advanced growth stages, and in those cases an insecticide application may not be economically justified. However, there are still many fields before the R6 stage that need attention, especially double-crop soybean fields and all these stink bug species feed on soybean pods reducing bean quality and reducing bean quality and increasing the risk of disease transmission. Because full-season soybeans are planted earlier, they often serve as a source of pests and diseases that later move into double-crop fields, which develop later and remain vulnerable for a longer period. We encourage soybean growers to reinforce or initiate consistent stink bug monitoring efforts, as regular scouting is key to early detection and effective control.
Reference
Falcon-Brindis, A. and Villanueva, R.T., 2024. Checklist and key to species of stink bugs (Hemiptera, Heteroptera, Pentatomidae) of Kentucky, United States of America. ZooKeys, 1213, p.75.
| Citation: Batista, F., Villanueva, R., 2025. Stink Bug Appearance Delayed in 2025 Western Kentucky Soybeans. Kentucky Field Crops News, Vol 1, Issue 9. University of Kentucky, September 12, 2025. |
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