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Stink bugs are a group of insects which often overwinter as adults and feed using their piercing-sucking mouthparts to suck up plant juices. Although many species of stink bugs are present in Missouri, the brown stink bug is the most common species causing damage to field corn and the green stink bug predominately damages soybean. Several problems with brown stink bugs in corn have been reported during the past several weeks. The economic threshold for this insect on corn is to treat when stinkbug damage occurs on 3 to 5 percent or more of seedling plants. Mortality of plants may occur or those that survive may be twisted and disfigured similar to 2-4-D damage. Seedling corn which survives stink bug attack often produces tillers and greatly reduced yield. Damage is often restricted to border rows in the field as stink bug overwinter in woody border areas and move into the field gradually causing an "edge effect" of damage. Severe infestations may require an insecticide application prior to replanting or a spot treatment of insecticide applied along the edge of the field. Most damage from stink bugs to corn occurs during the seedling stage of growth. High numbers of stink bug may cause a distorted, twisted ear if feeding occurs at the time of silking, although this type of damage is not often found at economic levels in Missouri.

The green stink bug generally causes most damage to soybean where adults and nymphs feed from June until frost. Similar to the brown stink bug, several generations may occur during the season with both adults and various nymph stages present. Green stink bugs feed by sucking plant juices from soybean, but does not cause the twisting and plant distortion observed in seedling corn. However, heavy feeding by green stink bug can result in "delayed senescence" of the soybean plant. The stems, leaves, and pods of damaged plants will remain green long after non-damaged plants in the field mature and dry. In Missouri research plots as few as 5 stink bugs caged on a square yard of soybean plants for a period of 10 days beginning at plant growth stage R-3 resulted in "delayed senescence" later in the season. The economic threshold for stink bug in soybean is to treat when 1 or more adult or large nymphs are present per foot during pod fill.

Wayne Bailey
BaileyW@missouri.edu