This damage causes severe economic loss, and may go unnoticed until harvest. Scouting and Control Thresholds Because corn earworm moths lay their eggs on the silks and the larvae crawl directly into the ears, field scouting is not an effective way to monitor for this insect. Therefore, control recommendations are made based on the number of corn earworm moths caught in pheromone traps on a nightly or weekly average. The traps should be baited with Hercon Helicoverpa zea or an equally effective pheromone. Place traps in corn fields just as the fresh green silks begin to appear.
Place traps so that the base is at the same height as the silks.
Traps should be checked at least once a week until the first CEW moth is caught, and checked two to three times a week thereafter. A treatment is recommended on any fresh silking corn when the first corn earworm is caught. Spray intervals after the initial application should be based on the number of moths caught on a nightly basis. If maximum daily temperature is less than 80 F, lengthen the spray interval by one day. The table above provides the spray thresholds you can use to determine if control measures are necessary based on the number of CEW moths caught in pheromone traps.