As collections manager at London's Natural History Museum, Max Barclay has traveled the world in search of rare and previously undiscovered insects. So when his 5-year-old son took a break from a picnic lunch last March in the museum's garden and returned with an insect in his hand, Barclay could not have guessed that his question--"Daddy, what's this?"--would lead to a global detective hunt that has so far stumped Barclay and the world's other entomologists.
Despite working with an insect collection of more than 28 million specimens, Barclay and his colleagues have been unable to identify the almond-shaped critter, about the...