Blister beetles are showing up in area alfalfa fields and that is a cause for concern according to Eldon Cole, a livestock specialist with University of Missouri Extension.
"Blister beetles poise a poison risk to livestock, especially horses," said Cole.
The compound causing the poisoning is cantharidin which causes blistering of the mouth, tongue and digestive tract. Death loss can occur in horses, depending on the size of the animal and the quantity of beetles in the baled hay.
According to Cole, the primary cause of poisoning is the crushing of the beetles in the haying process. Crimpers used to speed the drying process of hay will crush the beetles and release the toxic compound into the hay.
Cantharidin is a stable material so it will stay in the hay once it's contaminated.
"As with many toxins, the severity of the problem depends on the dosage level. Ruminants are not as sensitive to the toxin but can be affected if levels are high," said Cole.
Blister beetles come in a variety of colors, gray, black and black/yellow striped. They like to feed on alfalfa blooms but may show up in red clover and soybean fields.
The University of Arkansas has a fact sheet (FSA7054) "Blister Beetle Management in Alfalfa," online that answers several questions for producers that have the beetles in their alfalfa.
Source: University of Missouri Extension