Crater Lake is experiencing a migration of butterflies resembling the flights of locusts which perturbed the Pharaohs of Egypt in ancient times. About the South Rim one encounters hundreds of these insects, but on Garfield and Scott Peaks one may see thousands and tens of thousands, and multitudes are reported to be on the wing elsewhere.

They seem to fly from all directions, headed for everywhere at once, like a confused whirl-wind. Most of them, however, cross the Lake from the north, perhaps in anticipation of a pleasant winter in California, but many are enamoured by the beauty of Crater Lake, and fly around the Rim. When automobiles arrive, the front of their radiators are lavishly decorated with the mottled orange wings of these butterflies.

The great majority of these insects are the California Tortoise-shell Butterflies (Aglais californica Bdv.), whose wings are brilliant orange within, but grayish-brown on the outer surfaces. When they settle upon a tree trunk, or a stone, or a stray Ranger, they close their wings, and become very inconspicuous, safe in their protective camouflage. But the instant the wings are opened, the momentary concealment vanishes completely. It seems to be a conception of wide popularity that butterflies live for only a few days at best, but these insects refute that theory, and actually hibernate over the winter! The black, velvety caterpillars feed on various species of the Mountain or California Lilac (Ceanothus), which locally pass under the names of Snowbrush, Deerbrush or Buckbrush. A few whiter butterflies: Pine Whites (Neophasia monapia F. & F.), and Parassians (Parnassus clodius Mon.) are mingled with them, perhaps also succumbing to the vagrant urge.

The cause and destination of migratory movement has served tourists, and even newspapers, with much food for conjecture and speculation. J. A. Comstock, in his "Butterflies of California", explains the phenomenon as follows:

"It is not the response to an instinct that prompts a southward movement in the fall for the purpose of overwintering in favorable environment, but rather is determined by the scarcity of food-plant, and perhaps to some extent by the sudden subsidence of the several parasites... When conditions are right for the production of swarms of this butterfly it is noted that the Ceanothus bushes are entirely defoliated over great stretches of territory in our mountains. The butterflies are compelled to move on to other districts in order to find sufficient food-plant on which to lay their eggs. We do not know factors that determine the direction of this movement. Possibly it is related to the prevailing direction of the wind since it is easier for butterflies to fly against the wind than with it."

Tragedy lurks everywhere in the path of the voyagers. Automobiles and careless pedestrians take a heavy toll, but many more drop too near the water, and are drawn to its glassy, treacherous surface. While this may be a calamity to the butterflies, the fish appear to appreciate the addition to their staple diet, and may frequently be seen jumping for a highly ornamented, tasty morsel.