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Issue No. 11, Article 2/June 9, 2006

An Inventory of Field Crop Insect Issues in the Midwest

On June 6, extension entomologists from Illinois, Indiana, Iowa, Minnesota, Missouri, Nebraska, Ohio, and Wisconsin convened during a teleconference to share information about insect situations and issues in their eight respective states. A summary of the reports suggests a diversity of insect problems but no widespread outbreaks. Some common themes were the appearance of threatening numbers of armyworms in corn, wheat, and pastures in some areas; declining reports of black cutworm infestations; large densities of bean leaf beetles in some areas; and late-instar alfalfa weevils damaging alfalfa regrowing after the first harvest. Several entomologists noted that the low rates of seed-applied insecticides (Cruiser, Poncho) had not been very effective against black cutworms this spring.

Black cutworm larva and injury to lower portion of a cornstalk (photo courtesy of Robert Bellm, University of Illinois Extension).

Corn plant killed by black cutworm larva drilling into lower portion of stalk (photo courtesy of Robert Bellm, University of Illinois Extension).

Following are synopses of reports from the eight states:

Illinois (Mike Gray, Kevin Steffey)

  • Confirmed hatch of rootworm larvae on May 29.
  • Lingering reports of black cutworm damage.
  • Flights of European corn borer moths are under way. Captures of moths in pheromone traps thus far have been low.
  • The springtail and cricket "oddity" in a Henderson County soybean field.
  • No reports of soybean aphids in soybeans.

Indiana (Christian Krupke, Purdue University)

  • Armyworm larvae causing scattered problems in wheat, timothy, and pastures, mostly in southern Indiana.
  • Black cutworm problems are dissipating; considerable replanting has occurred.
  • Corn rootworm larval hatch was confirmed near West Lafayette on June 1.

Iowa (Marlin Rice, Iowa State University)

  • Soybean aphids were found in a soybean field near Ames (central) on May 31. As many as 40 per plant were counted, although this density was not common.
  • Bean leaf beetles are widespread and abundant, with some insecticide application to seed and food-grade soybeans.
  • Alfalfa weevils are damaging regrowth.
  • A handful of reports of severe infestations of wireworms.

Minnesota (Ken Ostlie, University of Minnesota)

  • Soybean aphids have been found in several fields (northwest, southwest, south central, southeast) as of June 1.
  • Lots of bean leaf beetle activity.
  • Some fieldwide infestations of wireworms.

Missouri (Wayne Bailey, University of Missouri)

  • Few armyworm problems, with reports diminishing.
  • Black cutworm problems, although diminishing, were significant in some areas, especially in the northwest.
  • Bean leaf beetles in central and northern Missouri, with some insecticides being applied.
  • Large numbers of stink bugs, especially the green stink bug (Acrosternum hilare), which might be of concern later in the season.

Nebraska (Bob Wright, University of Nebraska)

  • Rootworm larval hatch was confirmed on May 31 near Mead (east central), earlier near Clay Center (south central).
  • European corn borer flight under way; numbers are low.

Ohio (Ron Hammond, Ohio State University)

  • Diversity of problems--armyworms and cutworms, flea beetles, bean leaf beetles, slugs--but nothing widespread.

Wisconsin (Eileen Cullen, University of Wisconsin)

  • Late-instar alfalfa weevils are damaging alfalfa regrowing after the first cutting.
  • First call on an armyworm infestation on June 5 from Dodge County (south central).
  • Bean leaf beetles feeding on soybeans in southern counties.
  • Arrival of potato leafhoppers in alfalfa.

We sincerely appreciate the time that the entomologists in neighboring states spent providing an overview of insect issues. We hope this inventory gives you a snapshot of insect issues around the Midwest. As always, please contact any of us if you have information to share. We all appreciate the input.--Kevin Steffey and Mike Gray

Kevin Steffey
Mike Gray

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