In some species, the wings do not completely cover the abdomen. In Colorado, E. murina and E. fabricii often are most abundant in June, while other Epicauta species are more abundant in July and August. After emergence, adult blister beetles are strongly attracted to alfalfa and other blooming hosts. Adult feeding generally is not significant enough to warrant intervention. However, the presence of blister beetles in fields at harvest, particularly those species that swarm, is a concern for producers.
Blister beetles are a serious concern for hay producers and livestock owners.
Cantharidiasis or blister beetle poisoning occurs when livestock eat hay that contains cantharidin. Cantharidin irritates the gastrointestinal and urinary tracts of animals and may lead to death. Although most deaths are reported in horses, cattle and sheep also are susceptible. Symptoms include blisters on the tongue and in the mouth, colic, diarrhea, blood or intestinal lining discharge in stools, and problems with urination or bloody discharge in urine. If blister beetle poisoning is suspected, contact a veterinarian immediately.