In addition, because egg-laying moths prefer corn to beans, tomatoes, and other crops, borders or strips of corn planted as a trap crop around or within fields of other vegetables may reduce earworm densities on these less preferred crops. This approach is likely to provide some benefit only if the corn is silking at the same time as the beans, tomatoes, or other crops are setting pods or fruit. Monitoring Corn Earworm Populations Pheromone-baited traps can be used to monitor flights of corn earworm moths. Position the trap on a stake so that the bottom is 4 to 6 feet above the ground. Pheromone traps provide valuable but somewhat indefinite information about corn earworm populations.
Traps give very useful information about the timing of corn earworm flights.
Because females have emerged before males and are ready to begin egg-laying as soon as they mate, the capture of male moths in traps means that eggs will be deposited on susceptible hosts within hours. However, precise predictions of crop damage based on counts of moths in traps is not possible. Producers sometimes use a threshold of 10 moths per trap per night for sweet corn grown for processing or 5 moths per trap per night for fresh-mark sweet corn. For seed corn, control is recommended if significant moth flights occur when fresh silks are present. The interpretation of moth counts from traps is less clear-cut when pest management decisions focus on commercial production of snap beans or tomatoes.