Northern Illinois University

NIU Office of Public Affairs

David Changnon
David Changnon

Mike Sandstrom
Mike Sandstrom

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News Release

Contact: Tom Parisi, NIU Office of Public Affairs
(815) 753-3635

August 2, 2007

Where the bugs are

New ag-weather Web site predicts pest migrations

DeKalb, Ill. — Farmers have long known the breeze can carry crop-damaging bugs. Now a new Web site launched by Northern Illinois University tells agricultural producers in the Midwest which way the wind blows and when pests might be hitching a ride.

The agriculture weather site, located at, produces a daily Insect Migration Risk Forecast, geared for farmers, agricultural producers and entomologists. It was created and is maintained by NIU’s David Changnon, a professor of meteorology, and Mike Sandstrom, an NIU meteorologist and research associate.

“It’s a tool for people who need to know where the bugs are today and where they might be tomorrow,” Changnon says. “Farmers and others in the agricultural industry need to know just when insects might be migrating to their fields.”

Changnon says the site initially is focused on tracking the location and migration of corn earworm, a major pest of late-season sweet corn, but might be adapted in the future to track other insect migrations as well. Corn earworms migrate northward during the summer. If left uncontrolled, the pests can cause millions of dollars in damage to Midwestern corn crops in a single season.

The Web site was prompted by research that Changnon and Sandstrom conducted in recent years with entomologist Brian Flood, manager of pest management for vegetables for Del Monte Foods, which provided support for the Web site development.

“Our forecasting can tell the growers not only when and where pesticide treatments are necessary, but also if it is even necessary to spray,” Sandstrom says. “If weather conditions are not favorable for insect migration, there’s no sense spending the time and money involved with applying pesticides. Brian wanted something that would answer these questions. That’s how this Web site came about.”

Winds aid migration

Corn earworms migrate as moths, carried by winds. Cold fronts and rain prompt the moths to drop to the fields. “Part of our risk forecast identifies locations experiencing southerly wind and where the pests could drop out from the atmosphere, usually near a cold front or thunderstorm,” Changnon says.

The moths eventually lay eggs, which hatch into caterpillars that feed on the tips of ears of corn. Corn crops are susceptible to earworm during the silking phase.

“An earworm, if you don’t get it, will eat about 20 kernels of corn,” Flood says. “The ag-weather Web site provides a good predictive tool. Agriculture can’t be managed with historic weather maps alone. Growers have to be ahead of the game.”

NIU’s Analytical Center for Climate and Environmental Change at NIU provided funding for development of the agriculture-weather Web site. Research scientists Phil Young and Rick Schwantes in the Department of Geography provided the technical expertise needed to assemble the site.

For more information, contact Mike Sandstrom at or Dave Changnon at