Milkweed Tussock Moth or Euchaetes egle

"Euchaetes egle" is a moth in the family Arctiidae. It is a common mid- through late-summer feeder on milkweeds and dogbane. Like most species in this family, it has chemical defenses it acquires from its host plants, in this case, cardiac glycosides. These are retained in adults and deter bats, and presumably other predators, from feeding on them. Adults indicate their unpalatability with clicks from their tymbal organs.