In the west this lovely butterfly flies in the woods and brush along streams, circling lazily in the sun or dropping down to luxuriously stretch its wings upon a leaf. Try to catch it, however, and it flies off with great speed, dipping up and down in flight or even flinging itself skyward in a great leap that may take it out-of-sight. Often the orange tips of the wings flash in the sunlight in a way that must be confusing to a bird trying to catch the butterfly, for the movement of the wings causes this flashing of color to appear and then disappear.
The under side of the wings is quite different from that above, being of a mixture of soft, pale greens, whites and greys. So different is it indeed that it makes us suspicious the butterfly uses these colors for some kind of protective camouflage. This seems borne out when it lights among the light colored leaves of willows or cottonwoods and folds its wings over its back, for then the butterfly merges beautifully with the foliage.
The curiously mottled mixed brown and green caterpillar lives on willow and cottonwood leaves. It sometimes humps its body into almost a perfect S and holds so perfectly still that it may look like part of a willow twig, and so hides from enemies.