Pest Status: The blister beetle can become a pest when trapped in alfalfa as the hay is put up. Horses are especially susceptible to the toxin (cantharidin) produced by this beetle and may die after consuming only a few beetles.
Appearance: Adults have long (3/4 to 1 1/2-inch), narrow bodies and broad heads. They vary in color: gray, black, metallic, yellow- striped, or spotted.
Life Cycle: Adult female beetles lay their eggs in clusters in the soil. The first larval stages develop within a month, but the last two larval stages can remain for about 230 days before pupating. Pupating occurs in the spring and the stages last about two weeks, so adults appear in early summer.
Where to Collect: Adults usually gather in loose groups or swarms that feed on leaves of certain plants, especially legumes.
Purdue Extension Entomology, 901 West State Street, West Lafayette, IN 47907 USA, (765) 494-4554