New Blister Beetles of Montana MontGuide Available at Extension Office
MontGuide MT200209AG was developed by Hayes Goosey, MSU Forage Specialist; Tiziana Oppedisano, MSU Agronomic Entomologist and Agricultural Extension agents from Madison-Jefferson, Broadwater, Gallatin and Dawson Counties. The complete MontGuide is available at the Chouteau County Extension office or can be downloaded at MSU Publications.
Blister beetles are leaf-feeding insects that secrete a liquid that can cause blisters and can be toxic when accidentally fed to livestock in forage. Of the nine species observed in Montana, only one has been reported to have damaged crops. The MontGuide covers species found in Montana and discusses the risks of crop damage and livestock poisoning. Blister Beetles are named from a toxin called cantharidin found in their body fluids. When
the adult beetle is disturbed, “blood” containing this toxin is exuded from the leg joints. The fluid can cause blisters when in contact with the skin. Beetles killed during alfalfa harvest operations and incorporated into baled alfalfa can be toxic when fed to livestock. However, surveys of blister beetle species and seasonal occurrences conducted over several years in Montana have concluded that they are of minor concern to alfalfa producers or people who feed hay produced in Montana.
Monitoring to detect the presence and type of blister beetle present is important. If blister beetles are present at harvest, it is important to use harvest equipment that allows the beetles to escape from mowed and swathed forage because the type of equipment and its operation has an impact on blister beetle mortality during hay harvest. Research at Kansas State University has shown that self-propelled swathers without conditioning rollers but with windrowing attachments are safer than mower conditioners. Insecticides can be used to reduce populations. However, blister beetles are mobile and may move into the crop at any time. Residual activity of registered insecticides may not be sufficient to control blister beetles up to harvest.
Montana State University, U.S. Department of Agriculture and Montana Counties Cooperating MSU Extension is an equal opportunity/affirmative action provider of educational outreach.
