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Southwestern Corn Borer Moth Captures Common in Southern Illinois

June 1, 2001
Ron Hines, senior research specialist, Dixon Springs Agricultural Center, continues to capture southwestern corn borer moths in southern Illinois. Ron's first capture of southwestern corn borer moths occurred on May 18, 2001. According to our records, he caught his first southwestern corn borer moth last season on May 9. By keeping track of when southwestern corn borer moths have been captured in your area, you can begin to estimate important life-cycle events for this insect. After 190 heat units (base 50°F) have accumulated beyond the initial flight of southwestern corn borer moths, first instars can be found; second instars at 361 heat units; third instars at 533; fourth instars at 713; fifth instars at 902; pupation at 1,153; and emergence of adults at 1,321.

Each female southwestern corn borer moth deposits eggs in masses on the upper and lower surfaces of corn leaves. Female moths lay approximately 250 eggs over a 5- to 7-day life span. Eggs are yellow-green when first laid; however, after 36 hours they become cream colored with three orange-red lines on each egg. Economic infestations of the first generation of southwestern corn borers are not common, and most generally occur in corn planted near last season's infested and undisturbed corn residue. Yield losses caused by subsequent generations of this pest can be significant due to stalk lodging caused by the girdling of plants by larvae.

As the season progresses, we'll continue to keep you up to date regarding Ron's continued trapping efforts for southwestern corn borers in southern Illinois.--Mike Gray

Southwestern corn borer eggs. (Photo courtesy of Marlin E. Rice.)

Author: Mike Gray

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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