Pest Alert: Western Bean Cutworm in Sweet Corn

Western bean cutworm adult on corn ear. Photo credit: Adam Sisson, Iowa State University, bugwood.org

We are hearing reports of western bean cutworm activity in sweet corn this week. This species is relatively new to our region and can cause injury to sweet corn ears that is similar to corn earworm.

 Whitney Cranshaw, Colorado State University, bugwood.org
Western bean cutworm larvae feeding on the tip of an ear of sweet corn. Photo credit: Whitney Cranshaw, Colorado State University, bugwood.org

Scout tasseling fields by examining the upper surfaces of the leaves at the top of the plant, and leaves above and below the ear zone. Eggs are laid in masses and change from a cream color to lavender to dark purple as they age. Examine 20 consecutive plants at five locations in the field.

Western bean cutworm eggs. Photo credit: Frank Peairs, Colorado State University, bugwood.org

If you find more than 4% of plants have eggs or small larvae, consider protecting sweet corn when 90-95% of plants are at tassel. Materials used for corn earworm control will also control western bean cutworm. Consult the New England Vegetable Guide for recommendations.