Blister Beetle Toxicity in Horses

Blister beetles belong to a family of beetles called Meloidae. This family contains approximately 300 species distributed across the continental United States, including 150 in Arizona. Blister beetles have a peculiar life cycle. Females of some species lay eggs directly on plants and the emerged larvae interact with the host insect, while other blister beetles deposit clusters of eggs in small depressed areas of soil that form following rains and water runoff. The hatched larvae (called triungulin) feed on subterranean grasshopper egg pods or eggs of ground-nesting bees to complete development. The larvae pass through three growth stages (instars), with each becoming less active, and eventually they overwinter in the pupal stage. The adults emerge in the spring, and deposit eggs again in the summer to complete the cycle.