August 16, 2021

Identification of Early Season Insects in Corn

Early Season Corn Insect Pests, VE to V8

Below-Ground

When searching for below-ground pests, a small garden trowel or pocket knife is a handy tool to use. Some early-season insects are found attacking the seed (seedcorn maggot, seedcorn beetle) others may attack the seed and below-ground parts of the seedling (wireworm, sugarcane beetle), others are more limited to the roots (white grubs), and some attack the under-ground stem (sandhill cutworm). White grub is a generic term for the larval stage of insects like the Japanese beetle, rose or sand chafer, and May or June beetles. True white grubs are the larval stage of May and June beetles. To identify the grubs, the raster pattern, or the setae (hair) pattern on the posterior end is used. Michigan State University has developed an excellent publication, Severe grub damage spotted in northern Michigan hay field, that can be used to help identify white grubs in the field. Corn rootworm larvae may be present during the later stages of early season growth but may be too small to readily detect. If detected, they will have a brown to black head and a brown to black anal plate.

Wireworms.

Frank Peairs, Colorado State University, Bugwood.org.

Seed corn maggot.

White grub.

Alton N. Sparks, Jr., University of Georgia, Bugwood.org.

Sugarcane beetle.

Clemson University - USDA Cooperative Extension Slide Series.

Sandhill cutworm.

James Kalisch, University of Nebraska, Bugwood.org

Corn rootworm larvae.

Scott Bauer, USDA Agricultural Research Service, Bugwood.org

Above-Ground

Some of these insect pests feed above-ground but can also be found under-ground. The cutworm species feed above-ground at night but spend the day under soil clods.

Black cutworm.

Roger Schmidt, University of Wisconsin-Madison, Bugwood.org.