Cantharidin remains in the bodies of dead beetles and can still cause injury if baled with the hay. Therefore do not sell blister beetle infested hay to horse owners. Blister beetles overwinter as larvae in the soil and emerge as adults in the spring. Females deposit from 50 to several hundred eggs in the soil crevices. After hatching, larvae feed on grasshopper and cricket eggs.
Adults fly into fields, where they feed on foliage.
The beetles are usually found in late spring and summer. Hand pick but wear gloves to prevent blisters.