Be Prepared to Scout for the Bean Leaf Beetle

Published on: 09:16AM May 17, 2011

Dr. Roy Boykin

As we approach the summer months, be alert as temperatures and bean leaf beetle populations begin to rise. After overwintering in leaf litter and soybean residue, bean leaf beetles may already be emerging as they typically begin to appear in April and May. According to Kansas State University, the bean leaf beetle is one of the most economically harmful soybean insect pests in the country due to damage from foliage- and pod-feeding adults, which can significantly reduce seed quality and yield. It may be difficult to recognize this destructive insect as it can appear in a variety of colors and patterns, including red, orange, tan or gray and have dots, stripes or both. All adults possess a black triangle at the base of the forewings which is the easiest identification characteristic. 

Take note of the above description as it is important to scout diligently for bean leaf beetle this season. Due to the unusual weather patterns caused by the La Niña effect, it has been difficult for researchers and agronomists to make confident pest predictions. It is possible the weather patterns in some areas protected the bean leaf beetle from the typical harsh winter conditions that work to diminish its population, which could result in higher than normal infestations.
Adult bean leaf beetles can cause complete pod loss by feeding at the base of the pod, known as pod clipping. Moisture can then enter through the pod lesions caused by the pod clipping, allowing the entry of pathogens such as the bean pod mottle virus and southern mosaic virus, which can cause further yield loss. Be on the lookout for round holes between the major leaflet veins of your soybean leaves as this could be an indicator of bean leaf beetle feeding.

The University of Missouri Extension recommends scouting for bean leaf beetle begin as soon as soybean seedlings emerge. If you see signs of an infestation, it is important to note that various sampling methods and economic thresholds are used to trigger insecticide applications for bean leaf beetle, so check your local university extension for appropriate application information. When application is warranted, give your fields the best protection from bean leaf beetle by selecting an insecticide with three industry-leading technologies that offers long residual control for higher potential yield and profit.

Dr. Roy Boykin, Senior Technical Brand Manager, Insecticides, Syngenta Crop Protection
Roy is responsible for the technical development, positioning and product life cycle management of insecticides for all business units in the NAFTA Region. Roy received his undergraduate education at the College of Charleston with majors in biology and business and received his master’s/doctorate degrees in entomology with minors in plant pathology and crop science from North Carolina State University.