By Blake Jackson
Missouri soybean farmers should be vigilant in 2025 for several types of stink bugs that could threaten their crops, according to Ivair Valmorbida, a state crops entomologist at the University of Missouri Extension.
A 2024 survey revealed that the green stink bug was the most common in Missouri soybean fields, making up over 70% of the stink bug population. The one-spotted and brown stink bugs are also present and are similar in appearance. These pests overwinter as adults and emerge in the spring as temperatures rise.
Stink bugs are damaging to crops due to their piercing mouthparts. They feed on the blooms, pods, and developing seeds within the pods, which can lead to significant yield loss and reduced seed quality. Stink bugs vary in size and shape but are generally recognized by their shield-shaped bodies. Adult green stink bugs are typically light green, while their eggs are barrel-shaped, transitioning from light green to yellow, and are often found on the underside of leaves.
As soybean plants grow and approach the reproductive stages, stink bugs begin to migrate from field edges, and their numbers increase. Females lay eggs in masses, and the young nymphs stay in the same area during their early stages. As they mature into their fourth and fifth instars, the bugs spread throughout the field.
Valmorbida recommends insecticide use only when pest populations and damage exceed established thresholds. For grain soybeans, the threshold is 0.4 bugs per sweep (40 in 100 sweeps), while for seed beans, it’s 0.2 bugs per sweep (20 in 100 sweeps).
Farmers should scout their fields weekly once soybeans begin to bloom. Valmorbida suggests breaking large fields into 40-50 acre sections, taking into account soil type and pest history. When scouting, walk through the field in a pattern that avoids focusing only on field edges and assess the overall condition.
For additional monitoring, the University of Missouri’s Pest Monitoring Network offers free text alerts to keep farmers informed about insect activity in specific areas.
Photo Credit: istock-bee-photobee
Categories: Missouri, Crops, Soybeans