BugGuide actually classified it deeper in Subgenus Epicauta, Species-group Cinerea.
Feeding on Common Milkweed plants. Ash-gray Blister Beetle
Blister beetles are beetles (Coleoptera) of the family Meloidae, so called for their defensive secretion of a blistering agent, cantharidin. There are approximately 7,500 known species worldwide. Many are conspicuous and some aposematically colored, announcing their toxicity to would-be predators.