Integrated Crop Management is published by the Department of Entomology , Iowa State University , Ames, Iowa. Bean leaf beetle populations have reached economically damaging proportions in some parts of the state during the past 2 weeks. Large populations have reduced yields by 20-50 percent in past years so the importance of this insect should not be ignored.
Many fields contain noticeable, and sometimes dramatic, leaf defoliation from the beetles.
This leaf feeding seldom causes yield loss. This yield loss can occur in several ways. Pods may be clipped from the plants, or plant diseases may enter the pod through the feeding sites, causing seeds to appear shrunken, discolored, and moldy. This injury reduces seed quality. Beetles injure pods by feeding on the outside layer of the soybean pod, leaving a thin layer of tissue still covering the seed.