National Geographic : 1937 May
© National Geographic Society Painting by Hashime Murayama MONARCHS BY THE SQUADRONS GORGE ON GOLDENROD TO STORE ENERGY FOR THEIR MIGRATORY FLIGHT These nomads of North America are better known as "Milkweed Butterflies" (Danausplexippus) because the caterpillars feed onthat plant. During early autumn, adults frequently congregate in flocks and fly south for the winter. When spring comes, theymove northward again, sometimes reaching Hudson Bay and Alaska. Monarchs have spread to Madeira, Formosa, New Zealand, and Australia, wherethey arenow common. Afew specimens have been caught in Europe. Whether they flew across the ocean or were carried on ships still puzzles naturalists.