Corn Earworm

Helicoverpa zea

Corn Earworm is treated as a species-level fruit and ear feeder affecting corn ears, tomato fruit, cotton bolls, beans, peppers, and many flowering crops. Larvae enter corn ears through silks and tunnel into tomato or pepper fruit, leaving frass and secondary rot. One larva often dominates a feeding site because older larvae are cannibalistic.

Identification

Larvae vary from green to brown or pink, with longitudinal stripes and coarse microspines visible under magnification. Eggs are laid singly on silks, buds, or fruiting structures. The relevant host or site is corn ears, tomato fruit, cotton bolls, beans, peppers, and many flowering crops. Inspect fresh corn silks, tomato flower clusters, and fruit for eggs and small larvae. Pheromone traps help time scouting but do not replace crop inspection.

Symptoms / Signs

Larvae enter corn ears through silks and tunnel into tomato or pepper fruit, leaving frass and secondary rot. One larva often dominates a feeding site because older larvae are cannibalistic. Fresh feeding carries live larvae or new frass; old scars persist.

Life Cycle / Process

Eggs hatch quickly, larvae pass through several instars, and pupation occurs in soil. Moths are strong fliers and multiple generations occur. Larvae cause the damage, except grasshoppers, whose nymphs and adults chew. Control works best before larvae enlarge, bore, or seal themselves in silk.

Prevention

Inspect incoming plants and propagation material for eggs, small larvae, webbing, mines, or frass. Maintain crop records that link host stage with first egg or larval detection. Priority inspection target: corn ears. Focus species or category: Corn Earworm.

Management / Control

Protect silks or young fruit before larvae enter concealed sites. Bt sweet-corn programs and selective insecticides require precise timing and resistance rotation. Destroy crop residues and volunteer hosts. Base action on active feeding, larval size, crop stage, and tolerance. Killing moths or butterflies after eggs are laid does not reverse existing injury. Recheck the same unit for fewer larvae and less new feeding.

Procedure Steps

1. Inspect flowers, silks, buds, and young fruit for eggs, tiny larvae, or fresh frass. 2. Separate exposed larvae from individuals already inside ears, flowers, stems, or fruit. 3. Map nearby host crops and moth activity that may be contributing immigration. 4. Remove infested fruit or ears where practical and dispose of them away from production. 5. Time any Bt or selective labeled product before larvae enter concealed feeding sites. 6. Reinspect the next susceptible flower or fruit cohort rather than scoring old entry holes. 7. Close the Corn Earworm incident only after new injury stops.

Safety Notes

Protect food, seed, packaging, workers, and Myco-Patrons during inspection and treatment. Use tamper-resistant placements where baits or traps are necessary, and keep pesticides off food-contact surfaces. Structural or termite work may require a licensed Florida pest-control operator.