It is March 8, 1858, and John Hanning Speke is on an island in Lake Tanganyika trying vainly to hire a dhow from an Arab slaver, the better to explore the waters around him. That night, while he camps, a small beetle crawls into his ear and begins “to dig violently at my tympanum”. In terrible agony, Speke sticks a penknife blade in his ear and “applied the point . . . to [the beetle’s] back, which did more harm than good; for though a few thrusts quieted him, the point also wounded my ear so badly that suppuration took place and all the facial glands extending from that point down to the point of the shoulder became contorted . . . . It was the most painful thing I ever remember to have endured”.