Extension Entomologist Many insects may attack growing corn, but economic damage may not occur every year. In years of heavy infestations, any one of several insects may cause a loss in yield. To prevent loss, you must have knowledge of the insects and the most practical controls. In such cases, harvesting the crop as silage or fodder may be the best means of salvage.
Several aphids transmit a plant virus which causes a disease known as maize dwarf mosaic.
Insecticide control of the aphid is not an effective method of controlling the disease because the disease is transmitted prior to aphid death. The most effective means of virus management is the use of disease-tolerant varieties. Early Planting to Reduce Insect Damage Insect infestations are normally higher in late summer, so late planted corn is usually subject to more severe damage than early planted corn. Budworm damage is usually light until July and August. Infestations of first generation southwestern corn borer are much lighter than the second and third generations.