In the mid-1860s, grapevines in southeastern France inexplicably began to wither and die. Jules- mile Planchon, a botanist from Montpellier, was sent to investigate. He discovered that the vine roots were covered in microscopic yellow insects. What they were and where they had come from was a mystery. The infestation advanced with the relentlessness of an invading army and within a few years had spread across Europe, from Portugal to the Crimea. The...