Corn stalks that are heavily tunneled by European corn borer larvae may break over during strong winds or rainstorms. Frass at the break indicates that European corn borers were responsible for the injury.
European corn borer larvae often initiate their tunnels near the leaf axil (where the leaf extends away from the stalk). Frass indicates that a larva tunneled into the plant near that location.
European corn borer larvae often initiate their tunnels near the leaf axil (where the leaf extends away from the stalk). Frass indicates that a larva tunneled into the plant near that location. Strong winds make break the corn stalk near the tunnel.
European corn borer larvae rarely attack soybean plants but occasionally tunneling can be found in the main stem. Frass is an indication that a tunneling insect was inside the stalk.
European corn borers rarely infest soybeans but larvae occasionally have been found tunneling inside a soybean plant. There presence is often indicated by wilting leaves in the top of the plant.
Early-stage larvae feed on developing leaves inside the corn whorl. When the leaves emerge a series of small, repeating holes or long, narrow strips are indications that European corn borers may have caused the injury.
First-stage larvae are so small that they often don’t chew completely through a leaf. Their injury consists of small scrapings on the leaf surface that results in a translucent "window-pane".
Small holes called "shot holes" in newly developing leaves indicate that early-stage European corn borer larvae may be present inside the whorl causing additional injury.
