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Early-Season Insect Pests of Corn

April 20, 2001
Omar Koester, unit assistantcrop systems in Monroe and Randolph counties, reported that corn seedlings have emerged in his region, so it's not too early to remind people to begin watching for a slew of insects that attack corn early in the season. Some of them, such as grape colaspis, seedcorn maggots, white grubs, and wireworms, work underground, so aboveground symptoms of their feeding injury often are similar (for example, reduced plant populations, stunted and wilted plants). Other pests, such as billbugs, southern corn leaf beetles, and stink bugs, feed on plant parts above ground and cause characteristic feeding injury. For example, southern corn leaf beetles eat notches in corn leaves and stems, whereas stink bugs cause tissue necrosis by inserting their piercing­sucking mouthparts into the stem near the growing point.

It is very important to diagnose an insect problem accurately if any control tactics are to be considered. Remember, "rescue" treatments for grape colaspis, seedcorn maggots, white grubs, and wireworms are not effective. The only recourse if these insects are causing damage is to consider replanting. However, "rescue" treatments for control of billbugs, stink bugs, and southern corn leaf beetles can be effective if the insecticides are applied according to label directions.

As with any other insect problem, we appreciate receiving reports of "secondary" insect pests of corn as early as they occur. The sooner we learn about them, the sooner we can spread the word to alert others. Happy scouting!--Kevin Steffey

Author: Kevin Steffey

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

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