Blister Beetle Fact Sheet Is Now Available

University of Wisconsin – Madison Division of Extension Releases Blister Beetle Fact Sheet

(Madison) University of Wisconsin – Madison Division of Extension releases a blister beetle fact sheet, which can be found here:

Some important points to keep in mind when think about blister beetles are:

  • Poisoning by blister beetles is rare
  • All hay can potentially contain blister beetles, but alfalfa hay has a greater risk
  • Alfalfa blossoms can serve as a food source for adult blister beetles
  • Blister beetles contain cantharidin, a burning agent or poison
  • If equine and/or livestock animals display signs of toxicity, stop feeding your current hay source and contact your veterinarian immediately for diagnosis and treatment options
  • Onset of toxicity symptoms can take a few hours to days

For information released by University of Wisconsin – Madison, Wisconsin Veterinary Diagnostic Laboratory, please visit the following link: Dr. Keith Poulsen, Director of Wisconsin Veterinary Diagnostic Laboratory, can be contacted at or (608) 262 – 5422.

For more information, please contact your local Extension Educator; local veterinarian; forage testing facilities; PJ Liesch, Director of University of Wisconsin – Madison’s Insect Diagnostic Lab, at or (608) 262 – 6510; or Dr. Darlene Konkle, Wisconsin State Veterinarian, at or (608) 224 – 4884.

Equine and Blister Beetles Factsheet -PDF file