European corn borers feed on 200 plant species.
European corn borer (ECB) larvae are whitish with dark brown spots. Mature caterpillars are 3/4 to 1 inch long. Adult moths are patterned brown and tan and about 1/2 inch long. Eggs are laid in clusters on leaves. Freshly laid eggs are white and darken as they age. The larvae hatch and tunnel into the stem or fruit of the host plant.
Damage Caused by European Corn Borer
ECB feeds on over 200 species of plants and is a very important pepper, sweet corn, and tomato pest in Illinois. The caterpillars tunnel into pepper and tomato fruits, corncobs, or the stems of plants.
- Sweet corn: Caterpillars tunnel through the stem of the plant causing reduced yield and possibly stalk breakage.
- Peppers and beans: Caterpillars tunnel into the stems, which weakens them and reduces yield. They also tunnel into the fruit of peppers and the pods of beans. The caterpillars' entry into the fruit appears as a pinhole wound covered with frass. They cause more damage to bell peppers than hot peppers.
- Potato: Caterpillars will feed on potato leaves and bores into the stem, particularly in the first generation. This causes a yield reduction in some potato varieties.
Life Cycle of the European Corn Borer
- Larvae overwinter in the stems of plants. The females lay more eggs on warm, calm nights. The eggs hatch in about a week.
- The first generation of ECB tends to appear during May and June.
- The second generation emerges in July.
- There are two to three generations per year.
Management of European Corn Borer
Gardeners: Remove crop debris to help manage overwintering larvae. Us a pesticide when larva begin to appear.
- Sweet corn is typically planted several times during the growing season. The way in which the European corn borer attacks the plant depends on the growth stage of the plant rather than the time of year. In whorl-stage corn, scout for shot-hole feeding on leaves and for larvae in whorls. Treat during late whorl if more than 15 percent of plants show larval feeding. Treat before larvae bore from the whorl into the stalk. From tassel emergence through harvest, observe light traps for corn borer moths. Treat if counts exceed fifty moths per trap per night. Treat every five to seven days until ten to twelve days before harvest.
- Peppers should be treated at about five-day intervals when peppers are fruiting, if light traps are capturing more than five to ten European corn borer moths per night. The likelihood of damage is reduced if nearby corn is suitable for corn borer egg laying.
- Beans should be treated if light traps capture more than twenty-five moths per night and bean pods are at least 1 inch long. Treatment intervals vary from two to seven days, depending on the insecticide used. Larvae that hatch in the last two or three days before harvest will not mature enough to enter pods.
- Potatoes may have a problem if light traps capture more than twenty-five moths per night. Another indication of a potential problem is an average of more than one egg mass per twenty-five leaves. Action depends, in part, on the susceptibility of the potato varieties.
Contact your county Extension office for current pesticide controls.