Illinois Field Crop Applicators Practice Test

Which larvae are known for causing whorl damage and stalking tunneling in corn?

1. Black cutworms

2. European corn borers

3. Japanese beetles

4. Leaf aphids

The correct answer is: European corn borers

European corn borers are specifically known for causing significant whorl damage and stalk tunneling in corn. These larvae typically feed on the growing points of young corn plants, leading to the characteristic whorl injury as they consume the leaves that are still tightly rolled. Additionally, as they mature, they can tunnel into the stalks of the plants, which can result in weakening or even lodging of the corn plants later in the season. In contrast, black cutworms primarily target the base of corn plants and cut them off, leading to plant death but not to the same type of whorl damage. Japanese beetles are more focused on feeding on leaves and may not specifically attack the whorls or tunnel into the stalks. Leaf aphids, being sap suckers, do not cause physical damage in terms of tunneling or direct injury to the plant structure, but rather affect plant health by removing nutrients. Thus, the specific feeding behavior of European corn borers directly relates to the question regarding whorl damage and stalk tunneling.