Corn Earworm Infestation in a Garden

Corn earworm (USGS)

Corn earworm infestations in a garden can cause significant damage to corn crops, leading to reduced yields and decreased quality of the produce. These pests are the larvae of the corn earworm moth and feed on the developing kernels of corn.


  • Yellowing, wilting, or ragged leaves on the corn plant: This may be a sign that the pest is feeding on the sap of the plant, causing damage to the leaves and reducing the overall health of the corn plant.
  • Holes or ragged edges on the husks surrounding the ear of corn: The larvae may enter the ear of corn through these holes and feed on the developing kernels.
  • Damaged kernels on the ear of corn: The larvae may consume the kernels, leaving behind discolored or damaged kernels that are not suitable for consumption.
  • Presence of frass (insect excrement) on the leaves, ear, or ground near the corn plant: Frass may be present as a result of the larvae feeding on the plant, and can indicate a high population of the pests in the area.
  • Stunted growth or reduced yield: Infestations can lead to reduced growth and yields, as the pests feed on the developing kernels and sap of the plant. This can result in smaller, less desirable ears of corn.

What is a Corn Earworm

  • Color: The corn earworm is typically green in color, although its hue can vary from light green to a dark olive green.
  • Shape: The worm has a smooth, cylindrical shape and is approximately 1.5 inches long.
  • Head: The head of the worm is brown and slightly wider than its body.
  • Legs: The corn earworm has six legs, located near its head, which it uses to move and climb.
  • Mouthparts: The larvae have chewing mouthparts that they use to feed on the kernels and sap of the corn plant.
  • Markings: Some corn earworms may have white or yellow markings on their bodies. These markings can be used to distinguish them from other types of worm pests.
  • Life cycle: The corn earworm goes through several developmental stages, including an egg, larval, pupal, and adult stage. The larvae cause the most damage to the corn plant and are the stage to look out for in a garden.

Treating a Corn Earworm Infestation

Cultural Controls:

  • Proper crop rotation: Rotating the location of your corn crops can help reduce the build-up of the corn earworm population in your garden.
  • Sanitation: Regularly removing plant debris, such as fallen leaves and stalks, can help reduce the number of corn earworm pupae in the soil.
  • Early planting: Planting your corn early, before the peak flight time of the corn earworm moths, can help reduce the risk of infestation.

Chemical Controls:

  • Insecticides: Using insecticides labeled for use on corn earworms can help control the pest population. It is important to follow the label instructions carefully and to reapply as needed.
  • Bacillus thuringiensis (Bt): This naturally occurring bacterium produces a toxin that is toxic to corn earworms. Bt can be applied as a spray to the corn plants to control the larvae.

Physical Controls:

  • Hand picking: Regularly inspecting your corn plants and hand picking any visible larvae can help reduce the overall population of the pests.
  • Row covers: Placing row covers over the corn plants can help prevent adult corn earworm moths from laying their eggs on the plants.
  • Traps: Setting pheromone-based traps can help attract and trap adult corn earworm moths, reducing the number of eggs laid on the plants.

Biological Controls:

  • Natural predators: Encouraging natural predators, such as birds, parasitic wasps, and predatory insects, can help reduce the corn earworm population in your garden.
  • Beneficial insects: Introducing beneficial insects, such as ladybugs and lacewings, to your garden can help control the pest population by feeding on the larvae.