The amount of damage caused by aphids depends on the numbers present and moisture supply. In extremely dry years, severe infestations may cause large yield reductions. However, populations in excess of 300 to 400 per plant are usually needed to cause significant losses. While it is not uncommon to find scattered individual plants that are infested to this extent, widespread infestations at this level are rare. They are frequently found in the whorls of plants that have been damaged by armyworms or corn borers and in the tips of ears damaged by rootworm adults, corn borers, birds or corn earworms.
Sap beetles feed primarily on damaged tissue but do little damage themselves.
The larvae of the corn earworm range in color from green to brown. They reach a maximum length of 4 cm. Earworms feed on the silks and developing kernels near the tip of the ear. They do little direct damage themselves, but do expose the tip of the ear to invasion by other insects or diseases. This information is provided as a public service, but we cannot guarantee that the information is current or accurate.