Between the last pass of the combine and the first field check of spring, soybean insects such as soybean aphid and bean leaf beetle are quietly positioning themselves for a comeback. What you do in the off season, including tillage, crop rotation and scouting, can directly influence pest pressure, treatment needs and yield outcomes next season.
Know your soybean insects: Learn to locate bean leaf beetle and soybean aphid
Among the most persistent soybean insects you face are soybean aphid and bean leaf beetle. While both cause feeding damage and transmit diseases, their overwintering behaviors differ in ways that matter for your management plan.
Bean leaf beetle overwinters as adults in plant debris, woodlots, and field edges. They emerge early—often at or just before soybean planting—and are capable of inflicting damage at the seedling stage.
The potential for soybean aphid damage, by contrast, is established when this pest overwinters as eggs laid exclusively on common buckthorn buds. Buckthorn often grows unnoticed in wooded areas, windbreaks, creeks or fence lines next to fields. These eggs hatch in early spring and aphids migrate to soybean fields when plants are still young.
Disrupt soybean pests and their habitat
A multilayered strategy that includes tillage, residue management and crop rotation can help you effectively combat bean leaf beetle and soybean aphid damage.
Residue management for bean leaf beetle control and soybean aphid control
By taking a systematic approach and understanding the biology of these overwintering soybean insects, you can integrate a few strategic moves into your fall and spring routines that will dramatically cut their momentum.
Crop residue can harbor overwintering insects, especially the bean leaf beetle. They’re especially likely to survive if temperatures stay above 14 F for most of the winter months.1 Bean leaf beetles overwinter as adults and migrate to soybean fields when the crop begins to emerge. They go through two generations during the growing season. The second generation often appears in late August or even early September. Lingering high volumes of beetles can damage maturing pods. Removing excess crop residue over winter can give these soybean insects fewer safe havens.
Tillage strategy for soybean pests
Fall tillage is another tool that, when used appropriately, can expose and kill beetles sheltering in crop residue. It can also reduce the presence of overwintering weed debris, giving the bean leaf beetle fewer housing options. Keep in mind, though, that it’s important to strike the right balance between pest disruption and soil health, which might mean weaving other pest management strategies into a limited tillage or no-till environment.
Scouting guidelines for soybean insect pest management
Fall preparation makes spring soybean insect pest management more effective. Begin monitoring field edges early for signs of bean leaf beetle activity.
For soybean aphid, scouting should be conducted throughout the growing season, ideally once every week or week and a half.
Use crop rotation to break soybean aphid life cycle and bean leaf beetle life cycle
Rotating out of soybeans can help disrupt the lifecycle of both soybean aphid and bean leaf beetle. Non-host crops such as corn or wheat limit food sources and reduce pest survival over time.
Research suggests that a three- or four-year rotation of crops (for example, shifting from soybeans in year one to corn in year two to a small grain in year three) can be a greater deterrent to soybean aphid compared to a conventional, two-year corn-soybean rotation.2
Recommended application thresholds for bean leaf beetle and soybean aphid insecticides
You can consider insecticide application before R6 stage if there are at least 250 aphids per plant, aphid populations are growing and at least 80% of plants have been infested.3
For bean leaf beetle, insecticide applications are recommended when defoliation exceeds 30% during vegetative stages or when pod feeding threatens yield.4
Use an integrated approach to insect pests of soybean and their management
Integrated pest management means using all available tools wisely—cultural (rotation, residue reduction), mechanical (tillage), and chemical (threshold-based sprays). This approach will minimize insecticide resistance and protect beneficial insect populations. Sefina® insecticide can be used to control aphids including pyrethroid-resistant aphids without harming beneficial insects.
Experts are available to help you control soybean insects in your fields between seasons. Reach out to a local retailer, a nearby extension office agent, or a seed company professional like your regional BASF representative for more information on appropriate insecticides and seed treatment products.
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Endnotes
- Hodgson, Erin. “Bean Leaf Beetle.” Iowa State University Extension and Outreach, crops.extension.iastate.edu/encyclopedia/bean-leaf-beetle. Accessed 20 May 2025.
- Tilmon, Kelley, and Erin Hodgson. Effect of Crop Rotation on Soybean Aphid. Iowa State University, soybeanresearch.ppem.iastate.edu/project/effect-crop-rotation-soybean-aphid. Accessed 20 May 2025.
- Hodgson, Erin. “Soybean Aphid.” Iowa State University Extension and Outreach, crops.extension.iastate.edu/encyclopedia/soybean-aphid. Accessed 20 May 2025.
- Hodgson, Erin. “Bean Leaf Beetle.” Iowa State University Extension and Outreach, crops.extension.iastate.edu/encyclopedia/bean-leaf-beetle. Accessed 20 May 2025.
