Blister beetles are occasional late-summer problems in Iowa alfalfa fields. The beetles feed on alfalfa and soybean foliage, but leaf loss is not of economic importance. The real problem with blister beetles lies in their toxicity to livestock, especially horses, when accidentally consumed in feed. The beetles produce cantharidin, an irritant that causes painful blistering when the insects are handled. The cantharidin remains in the beetle's body even after it dies. That becomes a problem when alfalfa is swathed, during which dead blister beetles can be incorporated into the hay as it is made.
Iowa State University
Pope, Richard O. and Tollefson, Jon J., "Watch alfalfa for blister beetles" (1998). Integrated Crop Management News. 2244.
The Iowa State University Digital Repository provides access to Integrated Crop Management News for historical purposes only. Users are hereby notified that the content may be inaccurate, out of date, incomplete and/or may not meet the needs and requirements of the user. Users should make their own assessment of the information and whether it is suitable for their intended purpose. For current information on integrated crop management from Iowa State University Extension and Outreach, please visit https://crops.extension.iastate.edu/.