In early spring, researchers and Extension Educators monitor this insect's movement using traps to capture adult cutworm moths and determine when to start scouting for black cutworm larvae. An intensive moth capture occurs when 9 or more adult cutworm moths are caught over a two-day period. Intense captures have been reported in recently in many areas around the state. This intensive capture then becomes the base for counting degree-days, a measure of heating, that can be used to establish when the larva will be at the appropriate age (4th instar stage) and ready to start cutting or eating young corn plants. Between 312 and 364 degree-days are needed to reach the 4th instar larval stage.

Corn plants most at risk of damage from black cutworms are those in late planted fields that had a good stand of winter annual weeds. The adult female moth looks for weedy, grassy areas to lay her eggs. Corn fields with newly emerged plants in the 1-leaf to 4-leaf stage are most at risk for economic damage caused by larval feeding and cutting. With the uneven growth of corn occurring in fields this year, growers need to be scouting now for cutworms.

Scout your fields by checking 250 plants (50 plants in 5 different locations) for leaf feeding, cutting, wilting, and missing plants. Plan on checking fields at least once a week for the 3- to 4- week period following corn emergence. Collect 10 larvae and check their larval stage by using the head capsule gauge. A fact sheet with more information on the black cutworm, its life cycle, scouting procedures, and a rescue treatment calculator can be found online at: http://ipm.illinois.edu/fieldcrops/ insects/black_cutworm/index.html.

Dr. Mike Gray, U of I Professor of Entomology warns, "If you discover that 1% of your corn seedlings have leaf feeding; this injury signals that future cutting is possible at economic levels (3% to 5% cutting). Do not assume that Bt corn, insecticidal seed treatments, or the use of a soil insecticide at planting will eliminate the threat of black cutworm damage."

Rescue treatments may be needed when 3% or more of the plants are cut and larvae are still found. The rescue treatment calculator, found at the website above, can aid in the decision making process. According to Gray, "Most of the rescue treatment options involve using one of the many labeled pyrethroid products such as Asana XL, Baythroid XL, Mustang Max, Pounce, or Warrior. Lorsban 4E (an OP insecticide) also is labeled." Read and follow all insecticide label directions.