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Common Name: European corn borer                            Scientific name: Ostrinia nubilalis (Hübner)

Biology (life cycle):

Adult European corn borers have delta-shaped wings with wavy dark lines running across the surface. Adults infest the crop, and the lifecycle is very similar to sugarcane borer or rice stalk borer. Larvae of the European corn borer have a flesh-colored body that may have a grayish, greenish or pinkish tinge. Spots run the length of the body and may be the same color as the body. Larvae have two distinct light brown spots on the top of each abdominal segment and a distinctive mid-dorsal dark band. The head capsule is reddish to black in color.

Damage:

Damage caused by larva: Injury to rice results from stem borer larvae feeding on plant tissue as they tunnel inside the stem. Injury is often first noticed when the youngest partially unfurled leaf of the plant begins to wither and die, resulting in a condition called deadheart. Later in the growing season, these rice stems are weakened and may lodge before harvest. Stem feeding that occurs during panicle development causes partial or complete sterility and results in the whitehead condition. The white, empty panicles are light in weight and stand upright.

Management:

Facts: The European corn borer may increase its population densities in corn and grain sorghum before migrating to rice fields. It has the potential for severe infestations in rice in central and northern latitudes of Louisiana. In corn, European corn borer overwinters in the larval stage, with pupation and emergence of adults in early spring. Early infestations are noticed when the youngest partially unfurled leaf of the rice plant withers and dies, resulting in a condition called deadheart. Stem feeding during panicle development causes whiteheads. Severe infestations cause stalk breakage and plant lodging. Once larvae enter the stalk, pesticides are not effective.

What should you look for: Similar to the other stem borers, begin scouting for European corn borer at green ring and intensify at early boot stage. Look for orange lesions caused by the larva that feeds underneath the leaf sheath before it bores into stems. Peel off the leaf sheath to expose the feeding larva or to detect the presence of frass to ensure it is the stem borer and not sheath blight damage. Unfortunately, by the time signs of field infestations (deadhearts, whiteheads) are noted, it is usually too late to apply foliar insecticides effectively. Pheromone traps can assist in monitoring for European rice borer adults.

How you can manage European corn borer: Destroy crop residues after harvest to reduce overwintering borer population. Plant early, especially in areas with a history of borer infestations. Early planting allows the crops to mature before the beginning of moth migration from other crops and non-crop hosts. Apply insecticides to coincide with larval emergence so larvae are killed before they enter the rice stems. Once larvae enter the stems, foliar insecticides are not effective.

Insecticide option:

• Please see the Rice section of the Insect Pest Management Guide on the LSU AgCenter's Management Guides webpage.

Useful links:

• European Corn Borer and Other Borers in Rice (ppt. presentation).