The word “butterfly” probably originated because of the yellow color of European sulphurs. The clouded sulphur (also known as the common sulphur) is one of our most common butterflies, flying low over fields and lawns.
The adults are huge, mothlike, with large wings and a weak, fluttery flight. The fiercely predaceous aquatic larvae, called hellgrammites, are well-known to anglers, who often use them as bait.