Fall Armyworm

In-Depth Downloads

Pest Injury Symptoms and Impact on Crop

fall armyworm damage on corn ear
  • Fall armyworm larvae feed inside whorls on young plants
  • Feeding injury in leaves ranges from small shot holes to large ragged and elongated holes
  • Deep feeding in whorl may destroy developing tassel
  • Defoliation reduces photosynthetic area, which may stunt plants and reduce yield
  • Larvae will enter through the side of the ear and feed on developing kernels, reducing grain quality and yield
fall armyworm
fall armyworm feeding injury on corn leaf

Pest Facts of Fall Armyworm

  • Latin name is Spodoptera frugiperda
  • Are some of the most important pests in corn worldwide, especially in tropical climates, where they reside year-round in high numbers
  • Native to the southern United States and especially damaging on second plantings
  • Does not overwinter in most of the Corn Belt but moves north during the season on storms
  • Wide host plant range, including:
    • Corn, soybeans, cotton, bermudagrass, rice
    • Many broadleaf plants
    • Many small grains
  • Favorable conditions:
    • Semi-tropical and tropical climates
    • Late-planted corn in whorl stage
  • Natural enemies include parasitic wasps and flies, but these cannot reliably keep the pest in check
  • Unlike the regular armyworm and other moth larvae, the fall armyworm normally feeds during the day
Fall armyworm caterpillar
Parasitic wasp larvae clustered on a parasitized fall armyworm caterpillar

Key Characteristics of Fall Armyworm

  • Brown/gray larva with distinct tubercles along body
  • Three thin white stripes down the back and a distinct white inverted "Y" on head
  • Young larvae may be difficult to distinguish from corn earworm (CEW)
armyworm and earworm

Related Species

  • True Armyworm (AWM)
    • Subdued colors, present in large numbers
    • Smooth cuticle
  • Corn Earworm (CEW)
    • Bright, variable colors
    • Cuticle has "unshaven" look
  • Yellow Striped Armyworm (YSA)

    • Very bright, with yellow stripe
    • Dark spot

Life Cycle of Fall Armyworm

Fall Armyworm Life Cycle

IPM Practices

  • Scouting - scout late-planted fields as they reach V5-V8. Thresholds for treatment are based on defoliation levels and potential for FAW larvae entering the ear.
  • Pesticides are only effective on young larvae and before they enter the ear
  • Utilize early planting to avoid this and other pests

Management Considerations Using Pioneer Products

  • Pioneer Bt corn hybrids with Herculex® I or Herculex® XTRA provide a high level of resistance to FAW
  • Hybrids with only the YieldGuard® Corn Borer gene are much less effective
  • Biological controls: Parasitic wasps / flies - not reliable
corn comparison
Herculex® I hybrid (left) vs.YieldGard® Corn Borer hybrids (center and right)

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