Bean leaf beetle populations have reached economically damaging proportions in some parts of the state during the past 2 weeks. The largest populations appear to be in eastern Iowa (see map below showing bean leaf beetles per sweep), but reports of insecticide applications are coming from most of Iowa except the northern counties. Populations at this time are probably a mix of both the first- and second-generation beetles. You should expect second-generation bean leaf beetles to hang around until mid-September or until soybean plants start to turn yellow.
Iowa State University
Rice, Marlin E., "Bean leaf beetle numbers hit the roof" (2000). Integrated Crop Management News. 2013.
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