Such prolific oviposition allows corn earworm populations to compete well against parasites, predators, and environmental hazards. Immigrant moths may also express a resistant gene which increases their defense against chemical or biologically-based insecticides. Migration of pest insects away from treatment areas reduces the effectiveness of insecticide applications and releases of beneficial organisms. The LRGV annually produces about 200,000 ha of irrigated corn, which is considered a nursery crop for corn earworm populations. Entomological radars have been used to study migratory flights of corn earworms and other noctuids because the flights occur at night, high above the ground, and over long distances.
Radar images show that migrating insects are often aligned in a common direction.
Prevailing wind patterns in the Central U.S. offer persistent northward transport for migrating insects, especially at night. The wind jet occurred most frequently at night when the atmosphere becomes more thermally stable, reducing the frictional effect of surface roughness on wind speed. Several types of trapping systems have been used to confirm high-altitude flight of several noctuid species. Callahan et al. Beerwinkle et al.