Corn earworm found in corn

August 2, 2019 2:08 PM
Blog Post

Today in our corn efficacy evaluation trial, Ashley and our undergraduate team found small corn earworm caterpillars infesting ears (Figures 1 and 2). Caterpillars have a light-colored head but vary considerably in color from light green, tan, pink, maroon, and nearly black. However, they almost always have alternating dark and light lines running lengthwise down the thorax and abdomen and distinct tubercles (bumps) along the side of the body. They also have many black microspines on the body unlike most caterpillars with “smooth” skin.

Corn earworm.
Corn earworm. Photo by Ashley Dean. 

Corn earworm.
Corn earworm. Photo by Ashley Dean. 

Unlike European corn borer and fall armyworm that chew through the side or shank, corn earworm enter corn ears through the ear tip. Mature larvae can eat 8-15 kernels, or the top 2 inches of the ear tip. Feeding injury can provide pathways for fungal pathogens to enter the ear. The caterpillars, frass, and disease can be a contaminant when corn is harvested (especially important for sweet corn).


Erin Hodgson Professor

Dr. Erin Hodgson started working in the Department of Entomology, now the Department of Plant Pathology, Entomology, and Microbiology, at Iowa State University in 2009. She is a professor with extension and research responsibilities in corn and soybeans. She has a general background in integrated...

Ashley Dean Agriculture and Natural Resources Extension Specialist II

Ashley is an education extension specialist for field crop entomology at Iowa State University. She coordinates the Iowa Moth Trapping Network, the Regional Corn Rootworm Monitoring Network, and the Iowa Pest Alert Network. She also develops educational resources for field crop pests in Iowa and ...