Soybeans are a vital crop in Missouri, playing a significant role in the state’s economy. But like any major crop, soybean production faces persistent pressure from insect pests that threaten plant health, yield and seed quality. Understanding which insects are most problematic, and when they strike, is key to effective management and long-term sustainability.
Several insect species are known to impact soybean fields across the state. Their feeding behaviors vary, but each can inflict economic losses if left unchecked. The following pests represent some of the most common and damaging insects in Missouri soybean production systems.
BEAN LEAF BEETLE
Bean leaf beetles are among the earliest pests to appear each growing season. Adults chew small, round holes in young soybean leaves and may also scar pods later in the season, leading to seed discoloration and reduced market value. Populations typically peak twice per year — first in spring, then again in late summer as a new generation emerges. Consistent scouting and seed treatments can help suppress early infestations.
SOYBEAN APHID
Although less common in southern regions, soybean aphids continue to be a management concern in northern Missouri. These small, soft-bodied insects feed on plant sap, causing leaf curling, stunted growth and the production of honeydew — a sticky substance that promotes sooty mold. High populations can reduce pod development and yield, and aphids are known vectors for soybean mosaic virus. Economic thresholds are based on aphid counts per plant, making regular field monitoring essential.
JAPANESE BEETLE
Japanese beetles are metallic green with bronze wing covers and are notorious for skeletonizing soybean leaves. Heavy infestations can significantly reduce canopy leaf area, particularly during mid to late summer. These insects overwinter as grubs in the soil, feeding on grass roots before pupating and emerging as adults in early summer. Managing grassy field borders and timely foliar treatments can help mitigate outbreaks.
CORN EARWORM / SOYBEAN PODWORM
Often migrating from corn or other host crops, corn earworms (also known as soybean podworms) feed directly on soybean pods, damaging seeds and reducing yields. Infestations tend to be more severe in late-planted soybeans and during hot, dry conditions. Scouting for eggs and larvae during the R3–R6 growth stages helps determine whether treatment thresholds have been reached.
STINK BUGS (VARIOUS SPECIES)
Several stink bugs can cause extensive pod and seed injury by piercing the pod wall and feeding on developing seeds. Damaged seeds often shrivel or become discolored, reducing quality and marketability. Stink bug pressure tends to peak during the reproductive growth stages, emphasizing the importance of late-season scouting.
EMERGING CONCERN: TENTIFORM LEAFMINER
A relatively new pest in Missouri soybean fields, the tentiform leafminer was confirmed in central Missouri during late summer 2025. This small larva begins as white and turns pale green as it matures. Leafminers feed internally within leaves, creating visible “mines” or tunnels that do not cross the midrib — a key distinguishing feature when scouting for damage. Injury is most often concentrated along field edges and near wooded areas. Though not yet widespread, this pest warrants monitoring as populations establish.
INTEGRATED MANAGEMENT AND SCOUTING PRACTICES
Successful insect management begins with regular, systematic field scouting. Weekly inspections throughout the growing season allow early detection and identification of insect activity. Using sweep nets, visual observations and pheromone traps can help farmers make timely and informed decisions.
Integrated pest management (IPM) strategies combining cultural practices, resistant varieties, biological control and targeted pesticide use remain the most effective approach for long-term control. Understanding pest life cycles and environmental conditions helps ensure treatments are applied when most beneficial.
Insect management continues to be a critical component of soybean production in Missouri. By identifying key pests, monitoring infestations and adopting integrated control practices, farmers can reduce crop losses and maintain profitability. Continued research, field trials and extension outreach will remain essential to protecting Missouri soybean yields for years to come.
Photos from MU Integrated Pest Management.
