Bean Leaf Beetle in Soybean
Crop Injury: Bean leaf beetle (Cerotoma trifurcata) is a pest of soybean that causes damage throughout the soybean plant’s life cycle. The adult is primarily a defoliating insect but feeding on pods can also directly cause a decrease in seed quality and yield. When feeding on pods, it leaves a transparent inner skin that allows light and pathogens to damage the seeds. Bean leaf beetles can harbor bean pod mottle virus (BPMV) and other pathogens and may transmit these pathogens to soybeans. Virus transmission is generally most damaging to soybeans when it occurs during soybean vegetative stages.
Pest Description: Adult beetles are ¼ inch long and can vary in color; they are generally orange, tan, gray, and red. All adults, regardless of their primary color, display a distinguishing black triangle located on the back between the head and thorax. Some insects of all colors also have four black spots in the middle of the forewings, while other insects do not.
Bean leaf beetle feeding on soybean foliar tissue.
Iowa State University Integrated Pest Management Program.
Bean leaf beetle injury to soybean pods.
Adam Sisson
Life Cycle: One (northern United States) to three generations (southern United States) of bean leaf beetle occur every year. Adults from the previous season overwinter in leaf litter and emerge early in the spring, but numbers may be reduced from a harsh winter. This overwintering generation feeds on perennial legumes such as alfalfa before moving to soybean fields to feed and lay eggs. Eggs are laid in the soil near soybean plants. Larvae feed on soybean nodules and roots but are not believed to cause economic damage.
Bean leaf beetle life cycle in the Midwest United States.
Iowa State University Integrated Pest Management Program.
Scouting: Scouting for bean leaf beetle occurs throughout the growing season as they can be an economic pest from seed emergence until R7. Use a visual count on very small soybeans or a sweep net or ground cloth sampling method on larger plants to estimate the level of infestation and use thresholds developed by your state extension service to inform management decisions.
Management: Later planting dates normally have reduced early-season bean leaf beetle pressure because bean leaf beetles move to early-planted fields. Insecticide seed treatments control early-season bean leaf beetle and may be warranted to suppress populations in fields with consistent BPMV or bean leaf beetle problems. Foliar insecticides should only be used if beetles are present above local threshold levels.
Developed and reviewed by Fred Musser, Mississippi State University; Erin Hodgson, Iowa State University; and the Iowa State University Integrated Pest Management Program.
Bean leaf beetle feeding on soybean foliar tissue.
Bean leaf beetle injury to soybean pods.
Bean leaf beetle life cycle in the Midwest United States.
Bean leaf beetle leaf feeding appears as tissue skeletonization.
Bean leaf beetle adult
Bean leaf beetle adult
Gallery images courtesy Adam Sisson, Daren Mueller, and the Iowa State University Integrated Pest Management Program.
This publication was developed by the Crop Protection Network, a multi-state and international collaboration of university/provincial extension specialists and public/ private professionals that provides unbiased, research-based information to farmers and agricultural personnel. This information in this publication is only a guide, and the authors assume no liability for practices implemented based on this information. Reference to products in this publication is not intended to be an endorsement to the exclusion of others that may be similar. Individuals using such products assume responsibility for their use in accordance with current directions of the manufacturer.
In accordance with Federal civil rights law and U.S. Department of Agriculture (USDA) civil rights regulations and policies, the USDA, its Agencies, offices, and employees, and institutions participating in or administering USDA programs are prohibited from discriminating based on race, color, national origin, religion, sex, disability, age, marital status, family/parental status, income derived from a public assistance program, political beliefs, or reprisal or retaliation for prior civil rights activity, in any program or activity conducted or funded by USDA (not all bases apply to all programs). Remedies and complaint filing deadlines vary by program or incident.
Persons with disabilities who require alternative means of communication for program information (e.g., Braille, large print, audiotape, American Sign Language, etc.) should contact the State or local Agency that administers the program or contact USDA through the Telecommunications Relay Service at 711 (voice and TTY). Additionally, program information may be made available in languages other than English.
To file a program discrimination complaint, complete the USDA Program Discrimination Complaint Form, AD-3027, found online at How to File a Program Discrimination Complaint and at any USDA office or write a letter addressed to USDA and provide in the letter all of the information requested in the form. To request a copy of the complaint form, call (866) 632-9992. Submit your completed form or letter to USDA by: (1) mail: U.S. Department of Agriculture, Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, Mail Stop 9410, Washington, D.C. 20250-9410; (2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov.
This work is supported by the Crop Protection and Pest Management Extension Implementation Program from the U.S. Department of Agriculture’s National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and should not be construed to represent any official USDA or U.S. Government determination or policy.
USDA is an equal opportunity provider, employer, and lender.
©2025 by the Crop Protection Network. All rights reserved.
