Watch for Second Generation European Corn Borer Adults and Egg Masses

 

We have received a few reports of conventional corn fields being affected by first-generation European corn borer feeding. How do we know that European corn borer was causing the issues? When dissected, the corn stalks had obvious signs of internal feeding, and many of stalks contained a medium-sized brown pupa (Figure 1).

 

 

For much of South Dakota, European corn borers are capable of having two successful generations. However, in the northern counties of South Dakota, one generation of European corn borers occurs and feeds throughout most of the season. For the areas where two generations are possible, the second generation of adults should be emerging now and becoming active. This indicates that it is also a good time to start scouting conventional corn fields for European corn borer egg masses (Figure 2). These egg masses are located on the underside of corn leaves near the midrib that are right above or below the ear zone.