Weather produced a lot of misery for corn growers in 2009, but where insects were concerned Mother Nature cut them some slack. Bug problems for most farmers were modest, thanks to weather and resistant hybrids.

"Late corn planting and cool temperatures created a limited window for corn insects to be active,” explains Purdue University's Christian Krupke. "The corn crop was under very little drought stress, which is when you tend to see rootworm damage. Corn rootworms are always around, but their impact is greater if you have drought during or after the insects' feeding period.”

"With the ever-expanding use of Bt hybrids, we are not seeing as many problems with southwestern corn borer or European corn borer,” says Ric Bessin of the University of Kentucky.

Although there were few major insect outbreaks in 2009, there are lessons to be applied to insect management in 2010. Here's what entomologists are telling farmers this spring.

Western bean cutworm. "Growers need to be watching for western bean cutworm, which is a new pest in this area,” Purdue's Krupke says. "There were some fairly high damage levels this past year in northwestern Indiana counties.”

Western bean cutworm originated in the Great Plains and has been spreading into the Corn Belt. In recent years, it has been found in Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, North Dakota, Ohio, South Dakota and Wisconsin. Yield losses as high as 40% have been recorded in Colorado, where high populations were left untreated. Losses are lower, but still significant, in the Corn Belt.

"We haven't found any infestations of western bean cutworm in Ohio yet, but we are scouting for it,” says Ohio State University's Ron Hammond. "Last season, we caught close to 600 adults in traps—about five or six times as many as we did in previous years. We also saw our first caterpillar—but it was only one. We found no infestations of larvae.”

Emerging pests. Entomologists are watching what some of them call emerging pests—insects that are not major threats but might become significant in the future because they are not controlled by resistant hybrids.

"Japanese beetle is a newer field-crop pest in Iowa,” says Erin Hodgson of Iowa State University. "I'm encouraging growers in the eastern part of the state to be on the lookout for early signs of silk clipping.”

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