Field specialists and crop advisors in southern and western Iowa report the development of potentially serious corn leaf aphid infestations. Insecticide treatment is ineffective while the tassels are still in the whorl, but fields with in-whorl aphid populations need to be watched. Corn leaf aphids on a corn tassel. Aphids do not interfere with pollination unless most corn tassels are heavily covered with aphids and their honeydew secretions. Feeding by large colonies of aphids can reduce yields significantly.
Aphid colonies can slowly kill the tassel and top few leaves of a corn plant.
The plant responds by shunting nutrients to the feeding area and not to the developing ear, resulting in stunted ears or even barren plants. Nymphs look similar to adults, but they are smaller, lighter in color, and wingless. Aphids molt and leave shriveled white skins amid the colony. Beneficial insects usually parasitize some aphids, which helps reduce the population. Parasitized aphids can be recognized as swollen brown mummies that stick to the leaf.