Corn Earworm

Symptoms of Corn Earworm

corn tip with corn earworm damage
corn tip with corn earworm damage

  • They will frequently be near the tip but may feed down the ear creating a track of damaged kernels
  • The injury creates an ideal environment for ear fungi to invade and may lead to a quality problem at harvest

corn earworm damage down the ear

Pest ID

  • Note the lack of straight lateral lines or large tubercles on the sides of the western bean cutworm
Western bean cutworm

Western bean cutworm (photo above)

Fall armyworm

Fall armyworm (photo above)

Corn earworm

Corn earworm (photo above)

Pest Facts and Impact on Crop

  • Latin Name: Heliothiszea
  • Closely related or indistinguishable from:
    • Cotton bollworm: Helicoverpa armigera
    • Tobacco budworm: Heliothisvirescens, etc.
  • Importance
    • Grain losses estimated at 2.5% annually
    • Losses in southeastern U.S. as high as 16.7%
    • Losses in sweet corn as high as 50% in unsalable produce
  • Found worldwide but does not usually overwinter in most of the Corn Belt and must re-infest each year
  • Large range of hosts including corn, cotton, tobacco, tomatoes and other fleshy fruits and vegetables
  • In addition to the ear, occasionally larvae can be found in the whorl and foliage on younger plants

Corn earworm larvae


U.S. map showing overwintering areas for corn earworm.

Life Cycle

Annual life cycle for corn earworm.

IPM Practices

  • Trapping
    • Light traps or pheromone traps can indicate when adults are flying
  • Scouting
    • Scouting can be done in the field by looking for eggs on the green silks and turning back the silks at the tip of the ear to look for larvae
  • Management timing
    • Because the larva is exposed outside the ear for only a short time, economical timing of insecticides is difficult
    • Stop application after silks turn brown
  • Resistance available
    • Tight husks give some relief but real resistance is lacking except through the use of Bt hybrids
  • Pesticide use
    • In field corn, pesticide use is rarely warranted
    • Please check local accepted practices and label instructions when growing either sweet corn, seed corn or another specialty crop

Management of Corn Earworm

  • Favorable conditions
    • Trichogramma parasites infest some eggs but control is minimal
Best Management Practices Using Pioneer Products
  • Transgenic offerings
    • YieldGard® Corn Borer, Herculex® I and Herculex XTRA Insect Protection products provide suppression / moderate control of corn earworm populations
  • Beware that in cotton producing counties, additional requirements for refuge are required because of cross resistance of cotton bollworm / corn earworm to the YieldGard Bt gene

HX1 – Contains the Herculex® I Insect Protection gene which provides protection against European corn borer, southwestern corn borer, black cutworm, fall armyworm, lesser corn stalk borer, southern corn stalk borer, and sugarcane borer; and suppresses corn earworm.
HXX – Herculex® XTRA contains both the Herculex I and Herculex RW genes.
Herculex® Insect Protection technology by Dow AgroSciences and Pioneer Hi-Bred. Herculex® and the HX logo are registered trademarks of Dow AgroSciences LLC.
YGCB – The YieldGard® Corn Borer gene offers a high level of resistance to European corn borer, southwestern corn borer and southern cornstalk borer; moderate resistance to corn earworm and common stalk borer; and above average resistance to fall armyworm.
YieldGard®, the YieldGard Corn Borer design and Roundup Ready® are registered trademarks used under license from Monsanto Company.