Corn earworms are known to ruin sweet corn harvests, but these pests don't limit damage to corn. Also known as tomato fruitworms, they target crops from tomatoes and lettuces to legumes. Corn earworms are the larvae of small moths that lay eggs on plant leaves and corn tassels or silks. Multiple generations build up over summer months, but northern winters kill them. In southern climates, corn earworm pupae overwinter in soil. Moths emerge in spring, and some wing their way north.
Identification: Mature corn earworm moths have a wingspan of about 1 1/2 inches. Olive-gray to dusty brown, they have a dark spot on each forewing and dark bands across pale hind wings. The destructive larvae grow up to 2 inches long and have thorny microspines. Larvae vary in color; brown, green, pink or yellow are common. Alternating dark and light stripes running lengthwise down their bodies.
Signs/Damage: In corn crops, corn earworms damage the tips of ears first. Pull back the husks, and you'll find chewed kernels, excrement (called frass) and the feeding worm. Left unchecked, corn earworms eventually chew through the husk. On tomatoes, the pests chew holes into the fruit. Cut the fruit open, and you'll find tunnels, decaying tomato, extensive frass and the worm.
Control: If corn earworm moths appear, don't wait for damage before you treat. Timing is critical; once eggs hatch and larvae burrow, vegetables and fruits act as protection. GardenTech® brand offers several options to kill corn earworms and keep protecting for up to three months*. Spray as needed, but no more than once every seven days. These products treat corn up to three days before harvest, and tomatoes up to one day before you pick and eat.
- Sevin® Insect Killer Ready to Use simplifies target spot treatments for small numbers of plants. The adjustable nozzle lets you control the stream's width to spray narrow or wide.
- Sevin® Insect Killer Concentrate provides a simple, economical solution to treating larger areas of edibles with a pump-style sprayer. Use the easy-to-use measuring cap, add water to your sprayer, and mix well. Cover all plant surfaces thoroughly.
- Sevin® Insect Killer Ready to Spray, attached to a garden hose, mixes and measures as you spray. Covering corn and other edibles quickly and thoroughly is simple with this easy-to-use formulation.
Tip: Till your garden during fall or winter to kill overwintering pupae or expose them to cold. In summer, don't plant corn and tomatoes next to each other. Spacing provides added protection.
Always read product labels and follow the instructions carefully, including guidelines for pre-harvest intervals on edible crops.
*These products provide up to 3 month control on all listed insects except ticks.
GardenTech is a registered trademark of Gulfstream Home and Garden, Inc.
Sevin is a registered trademark of Tessenderlo Kerley, Inc.
- "Corn earworm, head" by USGS Bee Inventory and Monitoring Lab (Public domain)
- "Corn (Zea mays): Corn earworm (Helicoverpa zea)" by Scot Nelson licensed under CC BY 2.0
- "Corn earworm, moth, back" by USGS Bee Inventory and Monitoring Lab (Public domain)