Late-stage European corn borer larvae occasionally tunnel through the softer central tissues of the corn cob. The center of the corn cob may be used by the larva as an overwintering site.

Late-stage larvae typically tunnel into corn stalks. The tunneling injures the plant and can lead to stalk breakage during strong winds or rainstorms.

Fourth and fifth-stage larvae commonly tunnel into corn stalks. The tunneling can disrupt the flow of water and nutrients to from the roots to the growing parts of the plant.

Larvae tunneling into a corn stalk often expel frass (sawdust-like fecal material) from their tunnels. The frass may accumulate on the leaf below the tunnel entrance.

Larvae tunneling into a corn stalk often expel frass (sawdust-like fecal material) from their tunnels.

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.

Several European corn borer larvae feeding inside a corn whorl can cause extensive shot holes in leaves.

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.