Have you scouted your non-Bt corn fields? Currently, the population of borer larvae are reaching the critical third instar. Why is this stage critical? That is the age when larvae begin to tunnel stalks (figure 1) or enter ears. A check of some corn this week revealed the beginning of tunneling by about 30% of the larvae. Others aren’t to far behind.

There haven’t been many reports of treatable levels, but any non-Bt corn should be checked to assess infestations and the need for control. Once larvae tunnel into stalks or other plant structures, insecticides won’t reach the insect .