Pod feeding is usually limited to removal of the green tissue from the pod walls, causing a scarred appearance. Occasionally, they eat through the pod wall to the bean. University of Kentucky IPM Slide Set Insect counts or an assessment of plant damage can be used to determine whether or not a control needs to be applied. If damage is noticed, try to establish that bean leaf beetle is the problem and estimate the percent stand loss. During the vegetative stages, you may estimate the percent defoliation or count the number of beetles collected using a sweep net or a shake cloth.
All methods are equally reliable.
Calculate the average number of beetles per sweep. Consider an insecticide application if the beetle count reaches or exceeds the economic threshold in the table below. The average number of bean leaf beetles per sweep that will cause economic injury to soybean. Ground cloth procedure . Bend plants over the cloth and shake them vigorously.