Which of the following is considered an occasional corn insect pest?

The white grub is considered an occasional corn insect pest mainly because they do not consistently threaten corn crops but can still cause damage under certain conditions. White grubs are the larvae of various beetles, such as June bugs, and they typically feed on the roots of corn plants. While their populations can vary significantly from year to year, they may occur in fields where beetles lay their eggs, particularly in areas with poor soil management practices or in fields that have had recent turf damage.

Management of white grubs generally focuses on identifying and mitigating conditions that favor their growth and survival, and not on broad-spectrum controls, as their impact is not constant. Therefore, understanding their behavior and life cycle is crucial for effective pest management strategies in corn production.

The other options include more common pests or ones that have a more pronounced effect on corn, which is why they don’t fit the classification of "occasional." The Japanese beetle and corn flea beetle are known for their more regular interactions with corn and can cause significant damage. Spider mites, while also considered pests, are not typically grouped with insect pests of corn in the same manner as the others.