Hammerhead flatworms, which grow to a foot or more in length, do not belong in European vegetable gardens. "We do not have that in France," said Justine, a professor at the National Museum of Natural History in Paris. The predatory worms are native to Asia, where they happily gobble up earthworms under a warmer sun. The gardener who took the first photo, an amateur naturalist named Pierre Gros, emailed Justine a second picture a week later. It was of a completely different species of giant worm. … "The species are cryptic and soil-dwelling so can be easily overlooked, which often...