Blister beetles are especially attracted to alfalfa and weeds. Adults can be found on flowers or infested crops. Their bodies contain a toxin (cantharadin).
This toxin isa highly toxic chemical that irritates the gastrointestinal and urinary tracts and may lead to death, especially in horses.
Symptoms in horses are dependent on the amount of cantharidin eaten. If a large amount of cantharidin is consumed, a horse may die within 6 hours. If a small amount is consumed, only depression or mild colic (pawing, looking to the side, stretching) may occur.