western bean cutworm larva MER copy.jpg

Western bean cutworm


  • Adult: A brown moth with a 1½" wingspan. White stripe runs across the front edge of each wing, and below each stripe are two white spots.
  • Larvae: Start out dark brown with diamond-shaped markings on the back. Lighten to tan or pink as they mature and the back markings become more noticeable. Mature larvae have three stripes behind the head.
  • Eggs: White with a thin red ring on top. They later turn tan, then a deep purple. 

Timing of damage: V12 to R6

Type of damage: Larvae are very mobile and will feed on the leaves and tassel and cause extensive damage to the ear.

Scouting: Check 20 plants in five separate locations as soon as moths are noticed. Examine plant leaves for eggs and larvae and check tassels for larvae.

Economic threshold: Treat when 8% of the plants have egg masses or larvae.


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