Blister beetles: Biology and ecology

Blister beelte bleeding and skin burns: Reflexive bleeding through the leg joints of a blister beetle [top]. The hemolymph, or "blood," is highly toxic to vertebrates and may cause skin blisters [bottom].(Photo Marlin E. Rice)Blister beelte bleeding and skin burns: Reflexive bleeding through the leg joints of a blister beetle [top]. The hemolymph, or "blood," is highly toxic to vertebrates and may cause skin blisters [bottom].(Photo Marlin E. Rice)

Blister beetle populations can build up following grasshopper outbreaks. However, the often short-lived and infrequent grasshopper outbreaks in Iowa apparently do not lead to large blister beetle populations. In Iowa, adult blister beetles are found from late June through September (Pinto 1991) and are active day and night.

Eggs of this genus are deposited in the soil and newly-emerged larvae will seek out grasshopper eggs (Adams and Selander 1979). The larvae will develop through 5-9 stages and overwinter in the final stage. However, during adverse conditions larvae will delay development for two or more years.

Blister beetles are so named because their blood contains a toxic compound, cantharadin. Blister beetles can defend themselves by reflex bleeding through their joints and exposing any harasser to their toxic blood. This compound can cause blisters on skin (it is an active ingredient in some wart removers) and can be life-threatening to cattle, but especially horses, that consume infested hay.