• Fall armyworm, Spodoptera frugiperda, is a minor pest of corn in the United States.
• Economic damage is sporadic from year to year.
• Fields at highest risk from injury are:


• Fields planted to non-Bt hybrids without Lepidoptera control
• Fields in the southern U.S. and Texas
• Late-planted fields
• Late-maturing hybrids

• Early stage larval feeding:
  • Causes “windowpane” and shot holes in leaves
• Late-stage larval feeding:
  • Causes elongate, ragged holes (see photo below)
  • May cut leaves in half
  • Injures developing tassel in VT stage
  • Plugs whorl with wet, yellowish-brown frass

• Only larvae in whorl-stage corn can be controlled with insecticides; larvae in corn ears are protected
• Scout for larvae in whorl-stage corn:


• Select 20 consecutive plants in a row.
• Inspect plants for feeding injury.
• Confirm identity of pest species as fall armyworm.
• Repeat 20-plant sample at 4 additional locations.
• Determine percent infestations based on 100 plants.
• Consider insecticide application when 20% of whorl-stage plants are infested with live larvae.

Dark spots (tubercles) on dorsal surface arranged in "trapezoid" or when near the tail, in a "square" pattern. Spots are darkened in photo for emphasis.

Fall armyworms can be distinguished from similar corn caterpillars by 2 physical characteristics:

• Inverted “Y” pattern on the front of a dark head (see next 2 photos)
• Dark spots (tubercles) on dorsal surface arranged in “square” or “trapezoid” pattern (see third photo)