Milkweed Tussock Caterpillar - Euchaetes egle
This caterpillar sports wild tufts of black, white, and orange hairs (setae), which are characteristic warning colors.
As with monarch larvae, milkweed tussock caterpillars obtain cardiac glycosides from the milkweed that they feed on, and they continue to retain them as adults. But, while the milkweed tiger moth caterpillars have the bold warning colors of orange and black, the adult moth is drab and brown. Usually, you would expect the adults to also have bright warning colors just as the larvae do in order to scare off potential predators. However, the cardiac glycosides stored in the body of the moth are still put to good use, but in an unusual way. The milkweed tiger moth has an organ that emits an ultrasonic signal, which is easily detected by bats. The signal somehow warns that an attack will be rewarded with a noxious distasteful meal, and bats thus soon learn to avoid these tiger moths as potential prey.
''Euchaetes egle'', the Milkweed Tussock Caterpillar or Milkweed Tiger Moth, 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 . Only very high cardiac glycoside concentrations deterred bats, however. Adults indicate.. more