Animals: Butterfly Cloud

Northern Californians rubbed their eyes last week as Lake Tahoe turned orange. In Lassen National Park motorists cursed their overheated engines. Visitors to American River Canyon looked aloft, beheld a vast mottled cloud moving northwest. Natives of the Sierra Nevada foothills, remembering similar phenomena in 1926, 1919 and 1913, shrugged their shoulders and went back to work. They knew that these butterflies live off wild lilacs and other wild plants, do not harm domestic crops.

California's butterfly horde left the high Sierras two months ago, began moving northward toward the Sacramento Valley. Traveling 20 m. p. h. it moved...

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