Peak flight has passed for Western Bean Cutworm

Based on our western bean cutworm counts this week, peak flight of western bean cutworm has finally ended in most areas of Ohio.  There are a few traps where counts slightly increased, but across the state catches have largely crashed from last week. 

Adults may still be found, but as most of our corn has already tasseled, egg laying should be minimal and non-economic.  Scouting should continue, although it should concentrate more on the presence of larvae rather than egg masses.  Newly hatched larvae are small with dark, black heads.  As they mature, they become tan or pink in color, with grayish-brown longitudinal stripes. 

The later instar stages are readily identified by 2 broad black stripes immediately behind the orange head.  Larvae can be found on leaves or in leaf axils ingesting pollen.  Eventually, larvae will reach the corn ear and begin chewing on silk and the developing kernels.  Entry holes and tip damage may be visible, but most often removing the husk is necessary to fully determine larval presence.

Although we have not yet heard of a field were egg masses indicated economic threshold was reached, we recommend scouting corn ears, especially in late August and September. This will provide some estimate of western bean cutworm damage and feeding and predict where overwintering may occur and where to intensify management efforts for next year.