Disease & Pest Management

Black Cutworm in Corn

Lifecycle and Damage

  • Black cutworm moths arrive in the Midwest from the south each spring where they seek vegetation to lay their eggs
  • Cutworm larvae are light gray/black and may reach up to 2” in length
  • Early feeding by small larvae appears are small irregular holes
  • Cutting starts around the 4th instar as the worms mature
  • Cutworms at this stage can clip the plant at or below the soil surface (up to 3-4 plants per worm) causing it to stunt and wilt
  • At V6 the growing point of corn moves above ground; this is an important stage for determining whether or not plants may recover

Scouting

  • Target scouting in susceptible areas (weedy areas, high residue, etc.)
  • Scout weekly for 3-4 weeks after VE
  • Scout multiple areas throughout field
  • Record % of cuttings, corn growth stage and larval stage
  • A rescue insecticide application may be warranted at 3-5% leaf feeding OR 2+ cutworms per 100 plants