Ron Bellcock (Rod's Fertilizer, Galva, Iowa) reports finding cornfields with 20-25 percent of the tassels heavily covered with corn leaf aphids. In past years, I have seen fields with large populations that caused sufficient damage to make approximately 5 percent of the corn plants barren. Aphids do not interfere with pollination unless nearly all 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.