The Western Bean Cutworm (WBC) is increasing its footprint in the cornbelt.

Paula Davis, senior marketing manager for insect and disease control traits with DuPont says the pest started in Colorado and western Nebraska but over the past few years it has moved east. “Through Nebraska into Iowa and now we have them as far east as Ohio and Michigan. They’ve really increased their population throughout Iowa and northern Illinois.”

Infestations in Nebraska and Iowa have been enough to justify spraying with insecticide, “We usually use a threshold of about 8% of the plants with eggs for spraying.” Davis says insect damage can cause yield losses but then there will likely be quality problems as well from molds that grow on the injured plants.

The moths have been flying for about three weeks and now the eggs are being laid. “Eggs are laid on leaves above the ears; masses are approximately the size of your thumbnail, so they’re fairly evident. They’ll hatch within about four days of being laid, the egg masses are usually white and they turn darker.” Davis says once the larvae move down into the ear, insecticides are no longer effective. The moth is small and brown with two distinguishing marks, “A white circle on it’s forewing in a diamond-shaped area, it also has a white band on the front edge of the forewing.”

Davis says the pest is not a major problem at this time, but, left unchecked, it could easily become one “It’s a good one to keep an eye-out.”