
European Corn Borer
Ostrinia nubilalis
A widespread moth whose caterpillars bore into the stalks and ears of corn and also attack peppers, snap beans, and potatoes. By tunneling inside the plant they weaken stalks, break tassels, and open ears and pepper fruit to rot, often feeding out of sight until the damage is done.
🔎 How to spot it
The adult is a pale moth roughly an inch across with wavy yellow-brown lines on the wings, the males darker than the females. Eggs are laid in overlapping masses that look like fish scales on the underside of leaves. Young larvae are tiny and translucent with brown heads; mature larvae are flesh-colored, up to about an inch long, with a dark head and two small dark spots on each segment. Early signs are neat rows of shot-holes across young leaves where larvae fed in the whorl, later followed by sawdust-like frass at stalk and ear entry points.
🥀 Damage it causes
Larvae chew rows of holes in young leaves, then bore into stalks, tassels, ear shanks, and the ears themselves, as well as into pepper and bean fruit. Tunneling collapses stalks, breaks tassels, drops ears, and lets rot organisms in. In peppers the borers tunnel into the fruit near the cap, causing it to rot and drop.
🛡️ Prevent it
Shred and turn under or remove old corn stalks and stems after harvest to destroy the larvae that overwinter inside them. Plant so the most vulnerable stage does not line up with peak moth flights where that is known locally. Encourage the many natural enemies, and scout the whorl and emerging tassels so problems are caught while larvae are still exposed.
🧯 If it is already here
Control has to hit the young larvae while they are still feeding on the surface, before they bore in where sprays cannot reach. Bacillus thuringiensis (Bt) applied to the whorl and silks targets them with minimal harm to beneficials. Releases or conservation of Trichogramma egg parasitoids and predators such as lady beetles and minute pirate bugs also reduce numbers.
💡 Good to know
Once a borer is inside the stalk or ear it is protected, so timing against the small, exposed larvae is the whole game. In a home garden, fall cleanup of corn and pepper debris plus well-timed Bt usually keeps this pest manageable.
🌱 Plants it attacks
101 plants in the library can be attacked by this pest
Celebrity Tomato
Cherokee Purple Tomato
Elberta Peach
Norland Potato
Purple TomatilloFor educational and informational purposes only. Pest control advice is general guidance drawn from university cooperative extension sources; always identify a pest positively and read and follow the label on any product before use, especially around food crops, children, and pets.