Black Cutworm moths are starting to arrive in the Corn Belt with the recent weather fronts moving from southwest and we need to be ready with the rescue treatments, if necessary. We need to learn about their habits and what to look for while scouting. Some of the important points are as follows:
• Black cutworms can’t survive the winters in the Midwest. They fly south before the winter arrives.
• Every spring, moths come back with spring storms and lay eggs on grasses and weeds like mustards, chickweed or even winter wheat.
• From egg hatching to becoming adults it takes 40-50 days depending on temperatures. Even though cooler temperatures earlier may have killed some of the moths, warmer temperatures that followed increased the speed up their development and more will come. Some cutting activity has already been observed in Southern Illinois.
• Corn and soybeans are not their favorite hosts. When weeds are destroyed, larvae start feeding on corn. Small larvae feed on leaves. If you see small, irregular holes in the leaves, start looking for cutworms.
• Black cutworms feed above ground until they are about half inch long. It takes three instars to get to that stage. Each instar needs 100- 140 growing degrees.
• After about 300-400 accumulated GDs, at the fourth instar, watch out! Now these enemies of our corn crop are ready to do real damage and start cutting plants at or below ground level.
• Black cutworms are clever bugs. They hide during the day and feed at night. Scout your fields at least once a week and use suitable foliar insecticides, if needed, otherwise they might do serious damage to your crops.
• According to Purdue Entomologist, John Obermeyer, don’t think you are in the clear just because you have the insecticide coated seed because there are different levels of the coatings and lower levels may not provide full protection. His advice is to scout your fields and rescue your crops if needed. If your crop is under attack, good offence may be the best defense!