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Issue No. 6, Article 2/May 4, 2007

Black Cutworms: Spring Migration in Full Force

As we have reported in several issues of the Bulletin, intense captures of black cutworm moths have occurred throughout the state this spring. Producers have been encouraged to scout their corn fields (especially through the early seedling stages of 1 to 4 leaves) for pinhole feeding in leaves as a good predictor of potential cutting at a later date. Thorough scouting of corn fields for black cutworm injury is recommended, even in fields that have been planted with Bt seed. For more information on scouting and management recommendations, please visit this page on the University of Illinois Extension IPM website.


Black cutworm moths.

Recently I read through a paper (Annual Review of Entomology, 42: 393-425) published in 1997 by Dr. William B. Showers titled "Migratory Ecology of the Black Cutworm." Dr. Showers, a retired USDA entomologist, devoted much of his career at Iowa State University to researching the biology and ecology of black cutworms and the European corn borer. Provided here is some interesting information that I gleaned from his review paper.

  • The scientific name for black cutworms is Agrotis ipsilon (Hufnagel). This species also is known by many other common names, including black cutworm, greasy cutworm, floodplain cutworm, and dark sword grass cutworm.
  • Black cutworms can be found throughout the 48 contiguous states of the U.S. and in southern Canada, Mexico, Central America, and South America.
  • Black cutworms occur in other parts of the globe, including Hawaii, Australia, New Zealand, North Africa, Europe, and Asia.
  • Observations made in 1868 indicate that black cutworms were causing economic losses to seedling corn and seedling tobacco fields in the flood plains just west of St. Louis, Missouri.
  • Black cutworms have a very large host range and may be injurious to the seedling stages of corn, cotton, tobacco, wheat, and many species of vegetables.
  • Agronomic practices that favor establishment of winter annual weeds (common chickweed) and perennial weeds (mouse-eared chickweed) increase the likelihood of economic damage from black cutworm feeding.
  • "If there is a window of 8-14 days between tillage or herbicide application and corn planting, larval populations will be severely reduced, probably through dispersal and starvation."
  • "In the Northern Hemisphere, distribution of A. ipsilon between latitudes 10°-30°N, whether cited in the Mediterranean area, the Indian Subcontinent, or southern North America, seemingly has a unifying theme: The species is not present during the summer months, June-August." This observation may be related to poor pupal survivorship under hotter soil conditions that develop in more southern latitudes during the summer months. "A theoretical range of tolerance for this species might consist of pupal exposure to 0-36°C."
  • From 1985 to 1988, trapping studies (in central Iowa and northern Missouri) with pheromone and light traps confirmed that some (14 of 5,755 moths examined) black cutworm moths and armyworm moths had traveled from the lower Rio Grande Valley of southern Texas or from northeastern Mexico. This confirmation was based on the presence of exotic pollen (Ape's earring or Texas ebony, and False mesquite) on the mouthparts and eyes of captured moths.

Let us know if you encounter significant infestations of black cutworms this spring. We look forward to learning of your observations. --Mike Gray

Author:
Mike Gray

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