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.
Corn Earworm 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 run lengthwise down their bodies.
Signs or Damage of Corn Earworms
In corn crops, corn earworms damage the tips of ears first. Pull back the husks, and you'll find chewed kernels, earworm 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 corn earworm.
How to Control Corn Earworms
If corn earworm moths appear, don't wait for damage before you treat. Timing is critical; once eggs hatch and larvae burrow, the vegetables and fruits they're in act as protection. GardenTech brand offers several options to kill corn earworms and protect your harvest:
- Sevin Insect Killer Ready to Use2 simplifies target spot treatments for smaller areas and individual crops or plants. The adjustable nozzle lets you control the stream's width to spray narrow or wide and kill corn earworms on contact. Just shake the container and you're ready to go.
- 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 to measure concentrate into our sprayer, then add water to your sprayer and mix well. This product kills by contact and keeps protecting against corn earworms for up to three months.
- Sevin Insect Killer Dust Ready to Use starts killing corn earworms immediately upon contact. Just sprinkle a thin, even layer from the convenient shaker container to kill corn earworms on listed garden vegetables, including strawberries, cabbages and cucurbits.
Corn Earworm Control Tip: Till your garden during fall or winter to kill overwintering pupae or expose them to killing cold. In summer, don't plant corn and tomatoes next to each other. The extra spacing provides added protection.
Always read product labels thoroughly and follow instructions, including guidelines for listed plants and pests, application frequencies and pre-harvest intervals (PHI) for edible crops.
GardenTech is a registered trademark of Gulfstream Home & 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)
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