European Corn BorerLocation
The European Corn Borer, discovered in Massachusetts in 1917, has spread throughout most states east of the Rockies.
The corn borer eats more than just corn. It will bore into a wide variety of plants with large stems, stalks, and fruits, such as bell peppers, snap and lima beans, potato vines, tomatoes. It also attacks flowers: dahlias, gladiolus, and large-stemmed ornamental and weed plants.
European Corn Borer Appearance and Habits
The corn borer winters in larva form, an inch-long, flesh-colored caterpillar with inconspicuous black dots, in old stalks left around the garden and pupates in the same stalk. Yellow-brown moths appear in late May or June to lay white eggs on the underside of corn leaves over a period of 3 or 4 weeks. These eggs start hatching about a week later, and the young larvae chew small, round holes in leaves and move toward and into the plant stalk, leaving behind sawdust-like excrement on the leaves and outside the stalk. If you see bent stalks, the larvae have already done a lot of damage inside the plant.
How to Manage European Corn Borers
Uprooting, shredding, and burying infected stalks is the most successful method of destroying the corn borer because it kills the wintering larvae. Although this method does not salvage the affected plants, it will protect the next year’s harvest.
Late plantings are more vulnerable to the corn borer. Corn or other affected plants should be planted early, to grow while other plants are also bearing fruit.
Removing the borer by hand is the oldest remedy. Split the stem a little below the entrance hole and pick out the worm.
Other methods include attracting the corn borer moth to light traps, or using parasitic insects such as the ladybug, which will consume up to 60 borer eggs a day.
Spray natural pesticide BTK (http://gardenline.usask.ca/pests/bt.html) on undersides of leaves and into tips of ears after silks wilt.
Pictures of a European Corn Borer
- European Corn Borer (Life Cycle, page 51): A. adult moth; B. larva, a smooth caterpillar; C. pupa and larva inside corn stem, borer frass protruding from hole; D. female moth laying eggs on corn leaf; E. borer working in ear of corn, with frass protruding; F. borers overwintering in old corn stalks