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As corn planting is in full swing across the state, it’s important to be aware of early-season insect pests based on reports from the past couple of years in Louisiana. Here are some of key pests to watch out for:
Wireworm dug out of soil (A) and stunted corn caused by wireworm feeding (B), Natchitoches Parish, 2023. (Photos by J. Villegas)
Wireworms, the larvae of click beetles, are slender, brown or yellowish-brown, and have rigid, cylindrical bodies with a wire-like appearance. These larvae can live in the soil for several years, feeding on plant roots and other organic matter. Depending on the species, it takes around 3 to 5 years for the larvae to mature into adult beetles. In corn, wireworms cause significant damage by feeding on the roots, leading to stunted growth and reduced yields. This damage is particularly severe in seedling corn, as wireworm feeding reduces the plant's ability to absorb water and nutrients, making them more susceptible to stress and disease. Effective management of wireworms requires long-term strategies, such as crop rotation, which can disrupt the pest's life cycle and reduce their populations over several years. Tillage can also disrupt wireworm habitats, though it may not be suitable for all farming operations, such as no-till or reduced-till systems. Producers should carefully evaluate these strategies when designing a comprehensive wireworm management plan tailored to their fields' specific conditions.
The sugarcane beetle is a sporadic pest affecting several crops, including corn. This beetle is common throughout the southeastern U.S. Only the adult stage of the beetle causes injury to crops. In corn, the adults feed on seedlings below the soil surface, targeting the roots or the growing point of the plant. The damage caused by the beetles includes ragged, bean-sized holes at the base of the plants. This feeding behavior often results in terminal leaves dying, leading to stunted and nonproductive plants. Individual beetles are capable of damaging multiple plants in a row and severe infestations can significantly reduce plant stands, sometimes necessitating replanting. Monitoring infested fields for stand recovery as the crop matures is advised to manage the impact of these pests. Additionally, avoiding planting corn into sod or grassy fields and using high rates of seed treatments can help minimize seedling injury when beetles arrive in the field. Foliar application is not recommended as the beetles are protected underground.
Cutworm larva and feeding injury in seedling corn (Photo by Sebe Brown)
Cutworms are significant early-season pests of corn in the U.S. The larvae, which can grow up to 2 inches and are typically pale grey to black with a greasy texture, feed on plants at night or on overcast days and burrow into the soil during the day. Damage from smaller larvae causes “shot-hole” leaf feeding, while larger larvae can cut plants at or below soil level. Larvae may also sometimes bore into and tunnel within the stem. Mature larvae pupate in the soil. Effective management includes weed control before planting, as fields with heavy weed presence are at higher risk. Cutworms are usually problematic in reduced tillage or no-till fields that received a late burndown application, but clean fields should still be routinely scouted. Thresholds for cutworm damage in Louisiana corn are 6-8% for above-ground cutting or 2-4% for below-ground boring. Cooler weather keeps cutworms closer to the soil surface, while warmer weather drives them deeper into the soil, increasing the risk of injury to the growing point. Insecticide seed treatments and Bt technology may provide some protection, but large larvae are less susceptible. If necessary, a low label rate of a pyrethroid, such as bifenthrin, can reduce cutworm injury.
The 2025 Louisiana Field Crops Insect Pest Management Guide can be accessed using the link: Louisiana Insect Pest Management Guide
