For the first time, Taiwan closed a busy motorway section to make way for butterflies. The effort was to create a safe passageway for swarms of milkweed butterflies that flit along its city roads during their annual migration.

With white dots on purple-brown wings, these butterflies are indigenous to Taiwan. Each spring (in the last week of March and the first week of April), they fly to their summer home in northern Taiwan to breed. During this brief migratory peak, more than 11,000 butterflies pass the road every minute. The National Freeway Bureau imposed the traffic control on the Linnei section of Freeway no-3, between March 26 and April 6, 2007, so that the butterflies would not crash into vehicles. It also installed nets and ultraviolet lights along the motorway to guide the butterflies.

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