European corn borer in sweet corn
Young larvae feed first in the whorl and on the emerging tassel. When the tassel comes out, they move down and bore into the stalk and the ear. UF/IFAS puts the critical spray time just before or as the tassels emerge, while the larvae are still exposed. UF/IFAS says Bt products can be as effective as many chemical insecticides, though less so than some, and like any spray they must reach larvae that are still outside the plant. For grain corn, Bt hybrids now do most of the work.
At a glance
- Damage
- Tunnels in stalks and ears; holes under the pepper cap
- Type
- Chewing
- Settings
- Field, Garden
- Threshold
- More than 15% of plants with one or more larvae when emerging tassels are scouted (UMass, sweet corn)
- Ally
- Bacillus thuringiensis kurstaki
- Rate
- Label rate. DiPel DF lists European corn borer; 0.5–2.0 lb per acre on corn
How to confirm it
Small entry holes with frass on corn stalks, tassel stems or the side of the ear, and broken tassels. In peppers, a hole under the fruit cap. Split the stalk or fruit: the larva is up to about 1 inch (2.5 cm), light brown or pinkish-grey with round dark spots on each segment and a dark head.
Identification, lifecycle, degree days and every control option are on the full European corn borer profile. Not sure it is this pest? Answer four questions about the damage.